[{"awards": "1644234 Phillips, Fred", "bounds_geometry": "POLYGON((166.17 -77.3,166.32799999999997 -77.3,166.486 -77.3,166.644 -77.3,166.802 -77.3,166.95999999999998 -77.3,167.118 -77.3,167.276 -77.3,167.434 -77.3,167.59199999999998 -77.3,167.75 -77.3,167.75 -77.34,167.75 -77.38,167.75 -77.42,167.75 -77.46,167.75 -77.5,167.75 -77.54,167.75 -77.58,167.75 -77.62,167.75 -77.66,167.75 -77.7,167.59199999999998 -77.7,167.434 -77.7,167.276 -77.7,167.118 -77.7,166.95999999999998 -77.7,166.802 -77.7,166.644 -77.7,166.486 -77.7,166.32799999999997 -77.7,166.17 -77.7,166.17 -77.66,166.17 -77.62,166.17 -77.58,166.17 -77.54,166.17 -77.5,166.17 -77.46,166.17 -77.42,166.17 -77.38,166.17 -77.34,166.17 -77.3))", "dataset_titles": null, "datasets": null, "date_created": "Mon, 12 Dec 2022 00:00:00 GMT", "description": "Nontechnical Description: The age of rocks and soils at the surface of the Earth can help answer multiple questions that are important for human welfare, including: when did volcanoes erupt and are they likely to erupt again? when did glaciers advance and what do they tell us about climate? what is the frequency of hazards such as landslides, floods, and debris flows? how long does it take soils to form and is erosion of soils going to make farming unsustainable? One method that is used thousands of times every year to address these questions is called \u0027cosmogenic surface-exposure dating\u0027. This method takes advantage of cosmic rays, which are powerful protons and neutrons produced by supernova that constantly bombard the Earth\u0027s atmosphere. Some cosmic rays reach Earth\u0027s surface and produce nuclear reactions that result in rare isotopes. Measuring the quantity of the rare isotopes enables the length of time that the rock or soil has been exposed to the atmosphere to be calculated. The distribution of cosmic rays around the globe depends on Earth\u0027s magnetic field, and this distribution must be accurately known if useful exposure ages are to be obtained. Currently there are two remaining theories, narrowed down from many, of how to calculate this distribution. Measurements from a site that is at both high altitude and high latitude (close to the poles) are needed to test the two theories. This study involves both field and lab research and includes a Ph.D. student and an undergraduate student. The research team will collect rocks from lava flows on an active volcano in Antarctica named Mount Erebus and measure the amounts of two rare isotopes: 36Cl and 3He. The age of eruption of the samples will be determined using a highly accurate method that does not depend on cosmic rays, called 40Ar/39Ar dating. The two cosmic-ray theories will be used to calculate the ages of the samples using the 36Cl and 3He concentrations and will then be compared to the ages calculated from the 40Ar/39Ar dating. The accurate cosmic-ray theory will be the one that gives the same ages as the 40Ar/39Ar dating. Identification of the accurate theory will enable use of the cosmogenic surface dating methods anywhere on earth. Technical Description: Nuclides produced by cosmic rays in rocks at the surface of the earth are widely used for Quaternary geochronology and geomorphic studies and their use is increasing every year. The recently completed CRONUS-Earth Project (Cosmic-Ray Produced Nuclides on Earth) has systematically evaluated the production rates and theoretical underpinnings of cosmogenic nuclides. However, the CRONUS-Earth Project was not able to discriminate between the two leading theoretical approaches: the original Lal model (St) and the new Lifton-Sato-Dunai model (LSD). Mathematical models used to scale the production of the nuclides as a function of location on the earth, elevation, and magnetic field configuration are an essential component of this dating method. The inability to distinguish between the two models was because the predicted production rates did not differ sufficiently at the location of the calibration sites. The cosmogenic-nuclide production rates that are predicted by the two models differ significantly from each other at Erebus volcano, Antarctica. Mount Erebus is therefore an excellent site for testing which production model best describes actual cosmogenic-nuclide production variations over the globe. The research team recently measured 3He and 36Cl in mineral separates extracted from Erebus lava flows. The exposure ages for each nuclide were reproducible within each flow (~2% standard deviation) and in very good agreement between the 3He and the 36Cl ages. However, the ages calculated by the St and LSD scaling methods differ by ~15-25% due to the sensitivity of the production rate to the scaling at this latitude and elevation. These results lend confidence that Erebus qualifies as a suitable high- latitude/high-elevation calibration site. The remaining component that is still lacking is accurate and reliable independent (i.e., non-cosmogenic) ages, however, published 40Ar/39Ar ages are too imprecise and typically biased to older ages due to excess argon contained in melt inclusions. The research team\u0027s new 40Ar/39Ar data show that previous problems with Erebus anorthoclase geochronology are now overcome with modern mass spectrometry and better sample preparation. This indicates a high likelihood of success for this proposal in defining an accurate global scaling model. Although encouraging, much remains to be accomplished. This project will sample lava flows over 3 km in elevation and determine their 40Ar/39Ar and exposure ages. These combined data will discriminate between the two scaling methods, resulting in a preferred scaling model for global cosmogenic geochronology. The LSD method contains two sub-methods, the \u0027plain\u0027 LSD scales all nuclides the same, whereas LSDn scales each nuclide individually. The project can discriminate between these models using 3He and 36Cl data from lava flows at different elevations, because the first model predicts that the production ratio for these two nuclides will be invariant with elevation and the second that there should be ~10% difference over the range of elevations to be sampled. Finally, the project will provide a local, finite-age calibration site for cosmogenic-nuclide investigations in Antarctica.", "east": 167.75, "geometry": "POINT(166.95999999999998 -77.5)", "instruments": null, "is_usap_dc": true, "keywords": "AGE DETERMINATIONS; Mount Erebus; VOLCANO", "locations": "Mount Erebus", "north": -77.3, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Phillips, Fred; Kyle, Philip; Heizler, Matthew T", "platforms": null, "repositories": null, "science_programs": null, "south": -77.7, "title": "A Test of Global and Antarctic Models for Cosmogenic-nuclide Production Rates using High-precision Dating of 40Ar/39Ar Lava Flows from Mount Erebus", "uid": "p0010397", "west": 166.17}, {"awards": "1744771 Balco, Gregory", "bounds_geometry": "POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))", "dataset_titles": "5 million year transient Antarctic ice sheet model run with \"desensitized\" marine ice margin instabilities; 5 million year transient Antarctic ice sheet model run with \"sensitized\" marine ice margin instabilities", "datasets": [{"dataset_uid": "601602", "doi": "10.15784/601602", "keywords": "Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Sheet Modeling; Marine Ice Margin Instability; Model Output", "people": "Halberstadt, Anna Ruth; Buchband, Hannah; Balco, Gregory", "repository": "USAP-DC", "science_program": null, "title": "5 million year transient Antarctic ice sheet model run with \"sensitized\" marine ice margin instabilities", "url": "https://www.usap-dc.org/view/dataset/601602"}, {"dataset_uid": "601601", "doi": "10.15784/601601", "keywords": "Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Sheet Modeling; Marine Ice Margin Instability; Model Output", "people": "Balco, Gregory; Buchband, Hannah; Halberstadt, Anna Ruth", "repository": "USAP-DC", "science_program": null, "title": "5 million year transient Antarctic ice sheet model run with \"desensitized\" marine ice margin instabilities", "url": "https://www.usap-dc.org/view/dataset/601601"}], "date_created": "Tue, 21 Jun 2022 00:00:00 GMT", "description": "The purpose of this project is to use geological data that record past changes in the Antarctic ice sheets to test computer models for ice sheet change. The geologic data mainly consist of dated glacial deposits that are preserved above the level of the present ice sheet, and range in age from thousands to millions of years old. These provide information about the size, thickness, and rate of change of the ice sheets during past times when the ice sheets were larger than present. In addition, some of these data are from below the present ice surface and therefore also provide some information about past warm periods when ice sheets were most likely smaller than present. The primary purpose of the computer model is to predict future ice sheet changes, but because significant changes in the size of ice sheets are slow and likely occur over hundreds of years or longer, the only way to determine whether these models are accurate is to test their ability to reproduce past ice sheet changes. The primary purpose of this project is to carry out such a test. The research team will compile relevant geologic data, in some cases generate new data by dating additional deposits, and develop methods and software to compare data to model simulations. In addition, this project will (i) contribute to building and sustaining U.S. science capacity through postdoctoral training in geochronology, ice sheet modeling, and data science, and (ii) improve public access to geologic data and model simulations relevant to ice sheet change through online database and website development. Technical aspects of this project are primarily focused on the field of cosmogenic-nuclide exposure-dating, which is a method that relies on the production of rare stable and radio-nuclides by cosmic-ray interactions with rocks and minerals exposed at the Earth\u0027s surface. Because the advance and retreat of ice sheets results in alternating cosmic-ray exposure and shielding of underlying bedrock and surficial deposits, this technique is commonly used to date and reconstruct past ice sheet changes. First, this project will contribute to compiling and systematizing a large amount of cosmogenic-nuclide exposure age data collected in Antarctica during the past three decades. Second, it will generate additional geochemical data needed to improve the extent and usefulness of measurements of stable cosmogenic nuclides, cosmogenic neon-21 in particular, that are useful for constraining ice-sheet behavior on million-year timescales. Third, it will develop a computational framework for comparison of the geologic data set with existing numerical model simulations of Antarctic ice sheet change during the past several million years, with particular emphasis on model simulations of past warm periods, for example the middle Pliocene ca. 3-3.3 million years ago, during which the Antarctic ice sheets are hypothesized to have been substantially smaller than present. Fourth, guided by the results of this comparison, it will generate new model simulations aimed at improving agreement between model simulations and geologic data, as well as diagnosing which processes or parameterizations in the models are or are not well constrained by the data. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": null, "is_usap_dc": true, "keywords": "BERYLLIUM-10 ANALYSIS; AMD; ICE SHEETS; GLACIATION; Amd/Us; LABORATORY; USA/NSF; Antarctica; ALUMINUM-26 ANALYSIS; USAP-DC", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Glaciology", "paleo_time": null, "persons": "Balco, Gregory", "platforms": "OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Synoptic Evaluation of Long-Term Antarctic Ice Sheet Model Simulations using a Continent-Wide Database of Cosmogenic-Nuclide Measurements", "uid": "p0010342", "west": -180.0}, {"awards": "1643248 Hall, Brenda", "bounds_geometry": "POLYGON((163.3 -77.8,163.43 -77.8,163.56 -77.8,163.69 -77.8,163.82 -77.8,163.95 -77.8,164.08 -77.8,164.21 -77.8,164.34 -77.8,164.47 -77.8,164.6 -77.8,164.6 -77.85,164.6 -77.9,164.6 -77.95,164.6 -78,164.6 -78.05,164.6 -78.1,164.6 -78.15,164.6 -78.2,164.6 -78.25,164.6 -78.3,164.47 -78.3,164.34 -78.3,164.21 -78.3,164.08 -78.3,163.95 -78.3,163.82 -78.3,163.69 -78.3,163.56 -78.3,163.43 -78.3,163.3 -78.3,163.3 -78.25,163.3 -78.2,163.3 -78.15,163.3 -78.1,163.3 -78.05,163.3 -78,163.3 -77.95,163.3 -77.9,163.3 -77.85,163.3 -77.8))", "dataset_titles": "Marshall Valley Radiocarbon Data; Marshall Valley U-Series Data; Pyramid Trough Radiocarbon Data; Walcott Glacier area radiocarbon data; Walcott Glacier Exposure Data", "datasets": [{"dataset_uid": "601528", "doi": "10.15784/601528", "keywords": "234U/230Th Dating; Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Last Glacial Maximum; Marshall Drift; Marshall Valley; MIS 6; Royal Society Range", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Marshall Valley U-Series Data", "url": "https://www.usap-dc.org/view/dataset/601528"}, {"dataset_uid": "601615", "doi": "10.15784/601615", "keywords": "Algae; Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Howchin Glacier; Radiocarbon; Radiocarbon Dates; Ross Sea Drift; Royal Society Range; Walcott Glacier", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Walcott Glacier area radiocarbon data", "url": "https://www.usap-dc.org/view/dataset/601615"}, {"dataset_uid": "601614", "doi": "10.15784/601614", "keywords": "Algae; Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Pyramid Trough; Radiocarbon; Radiocarbon Dates; Ross Sea Drift; Royal Society Range", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Pyramid Trough Radiocarbon Data", "url": "https://www.usap-dc.org/view/dataset/601614"}, {"dataset_uid": "601616", "doi": "10.15784/601616", "keywords": "Antarctica; Beryllium-10; Exposure Age; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; McMurdo Sound; Royal Society Range; Walcott Glacier", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Walcott Glacier Exposure Data", "url": "https://www.usap-dc.org/view/dataset/601616"}, {"dataset_uid": "601529", "doi": "10.15784/601529", "keywords": "Algae; Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Marshall Valley; Radiocarbon; Ross Sea Drift; Royal Society Range", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Marshall Valley Radiocarbon Data", "url": "https://www.usap-dc.org/view/dataset/601529"}], "date_created": "Thu, 03 Mar 2022 00:00:00 GMT", "description": "Hall/1643248 This award supports a project to reconstruct the behavior of a portion of the East Antarctic Ice Sheet (the Ross Ice Sheet), using glacial geologic mapping and radiocarbon dating of algal deposits contained in glacial moraines, at the end of the last glacial period. The results will be compared with other dating methods that will be used on alpine glaciers that terminated in the mountains of the Royal Society Range in East Antarctica during the last glacial maximum and whose landforms intersect with those of the Ross Ice Sheet. Results from this comparison will contribute to a better understanding of the Antarctic ice sheet during the most recent global warming that ended the last ice age. This period is of interest since it will help inform our understanding of Antarctic ice sheet behavior in a future climate warming. Such data also will help inform models that attempt to simulate not only the behavior of the ice sheet during the end of the last ice age, but also its future response to elevated atmospheric carbon dioxide. The work will contribute to the education and training of both graduate and undergraduate students and results from the work will be incorporated in classes at the University of Maine. Results derived from the research will be disseminated to the public through lectures and visits to K-12 classrooms and data from this project will be downloadable from a University of Maine web site, as well as from public data repositories. The Antarctic Ice Sheet exerts a key control on global sea levels, both past and future, and strongly influences Southern Hemisphere and even global climate and ocean circulation. And yet a complete understanding of the evolution of the ice sheet over the last glacial cycle and of the mechanisms that caused it to advance and retreat is still lacking. Of particular interest is the response of the Antarctic Ice Sheet to the global warming that ended the last ice age, because it yields important clues about likely future ice-sheet behavior under a warming climate. In this project, scientists will reconstruct the thinning history of the Antarctic Ice Sheet in the Ross Sea sector during the last glacial/interglacial transition on the headlands of the southern Royal Society Range. They will use a combination of glacial geomorphological mapping and radiocarbon dating of algal deposits enclosed within recessional moraines. Finally, this record will be compared with a beryllium- and radiocarbon-dated chronology that will be produced of adjacent independent alpine glaciers that terminated on land during the last glacial maximum and whose deposits show cross-cutting relationships with those of the ice sheet. Results from this comparison will bear on the behavior of the Antarctic Ice Sheet during the termination of the last ice age. This work will support six students, including at least three undergraduates, and involves field work in the Antarctic.", "east": 164.6, "geometry": "POINT(163.95 -78.05)", "instruments": null, "is_usap_dc": true, "keywords": "GLACIER ELEVATION/ICE SHEET ELEVATION; Royal Society Range; USA/NSF; USAP-DC; Amd/Us; AMD; LABORATORY; GLACIAL LANDFORMS", "locations": "Royal Society Range", "north": -77.8, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Glaciology", "paleo_time": null, "persons": "Hall, Brenda; Denton, George", "platforms": "OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -78.3, "title": "Response of the Antarctic Ice Sheet to the last great global warming", "uid": "p0010301", "west": 163.3}, {"awards": "2138556 Halberstadt, Anna Ruth", "bounds_geometry": "POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))", "dataset_titles": null, "datasets": null, "date_created": "Tue, 09 Nov 2021 00:00:00 GMT", "description": "Geologic data provide crucial insights into Antarctic Ice Sheet dynamics; for example, progressive exposure of mountain peaks emerging from the ice sheet reveal ice elevation changes, and the past \u2018footprint\u2019 of marine-based ice sheets is imprinted on the seafloor. Numerical ice sheet simulations can link these geologic records in space and time to make larger-scale inferences about continent-wide ice sheet evolution. This work integrates both marine and terrestrial geologic datasets with numerical simulations to investigate Antarctic Ice Sheet behavior (and contribution to global sea level) throughout the last deglaciation, ~20,000 years ago until present. Specifically, this research addresses two issues regarding the relationship between simulations and data and their use in reconstructing past ice-sheet behavior: (1) Geologic records from the modern seafloor suggest significantly earlier retreat of marine-based ice compared to terrestrial records of mountain peak exposure (ice thinning). Computer experiments investigate several hypotheses for this mismatch in timing. (2) Exposure age data (terrestrial measurements recording ice elevation changes) are often interpreted to reflect ice dynamics hundreds of kilometers away from the study site. This work uses simulations to explore the linkage between ice elevation changes \u2018upstream\u2019 as glaciers flow through mountainous regions and ice dynamics further \u2018downstream\u2019 where ice contacts the ocean. This work will produce a publicly available, customizable, and easily accessible toolkit for comparing simulations and data, including a database of geologic records to use as constraints. The project is interdisciplinary, bridging a communication gap between the ice-sheet simulations and geologic data-collecting communities. This project combines numerical simulations and geologic data to explore fundamental knowledge gaps regarding the interpretation and use of marine and terrestrial datasets. This work will produce an ensemble of continent-wide coupled ice sheet and glacial isostatic adjustment simulations, constrained with comprehensive existing geologic data, to reproduce a history of deglacial Antarctic Ice Sheet evolution that is compatible with the geologic record as well as glaciologically and gravitationally self-consistent. Comparison between simulations and data is improved through high-resolution nested ice sheet modeling techniques, which provide unprecedented context for exposure age data generally located in regions of complex topography. Numerical simulations will be performed with systematically varied parameters and boundary conditions, and can thus support an investigation of (1) chronological mismatches between terrestrial thinning and marine ice sheet retreat during the mid-Holocene, and (2) how marine grounding-line dynamics are propagated upstream to coastal outlet glaciers and further interior under a variety of different scenarios. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": null, "is_usap_dc": true, "keywords": "Antarctic Ice Sheet; GLACIERS/ICE SHEETS; USAP-DC; USA/NSF; MODELS; AMD; Amd/Us", "locations": "Antarctic Ice Sheet", "north": -60.0, "nsf_funding_programs": "Post Doc/Travel", "paleo_time": null, "persons": "Halberstadt, Anna Ruth", "platforms": "OTHER \u003e MODELS \u003e MODELS", "repositories": null, "science_programs": null, "south": -90.0, "title": "OPP-PRF: High-resolution Nested Antarctic Ice Sheet Modeling to Reconcile Marine and Terrestrial Geologic Data", "uid": "p0010278", "west": -180.0}, {"awards": "1744949 Campbell, Seth; 1745015 Zimmerer, Matthew; 1744927 Mitrovica, Jerry", "bounds_geometry": "POLYGON((-145 -74,-141.6 -74,-138.2 -74,-134.8 -74,-131.4 -74,-128 -74,-124.6 -74,-121.2 -74,-117.8 -74,-114.4 -74,-111 -74,-111 -74.6,-111 -75.2,-111 -75.8,-111 -76.4,-111 -77,-111 -77.6,-111 -78.2,-111 -78.8,-111 -79.4,-111 -80,-114.4 -80,-117.8 -80,-121.2 -80,-124.6 -80,-128 -80,-131.4 -80,-134.8 -80,-138.2 -80,-141.6 -80,-145 -80,-145 -79.4,-145 -78.8,-145 -78.2,-145 -77.6,-145 -77,-145 -76.4,-145 -75.8,-145 -75.2,-145 -74.6,-145 -74))", "dataset_titles": "Mt. Waesche ground-penetrating radar data 2018-2019", "datasets": [{"dataset_uid": "601490", "doi": "10.15784/601490", "keywords": "Antarctica; GPR; Mt. Waesche", "people": "Braddock, Scott", "repository": "USAP-DC", "science_program": null, "title": "Mt. Waesche ground-penetrating radar data 2018-2019", "url": "https://www.usap-dc.org/view/dataset/601490"}], "date_created": "Fri, 22 Oct 2021 00:00:00 GMT", "description": "This study will collect a novel dataset to determine how the West Antarctic Ice Sheet (WAIS) responded to a warmer climate during the last interglacial period (~125,000 years ago) by reconstructing the glacial history at the Mt. Waesche volcano. Reconstructing WAIS geometry when the ice sheet was smaller than present is difficult and data are lacking because the evidence lies beneath the present ice sheet. This study will drill through the ice sheet and recover bedrock that can be analyzed for its surface exposure history to help determine when the surface became overridden by the ice sheet. This study will provide constraints on the past maximum and minimum spatial extent of WAIS during the last glacial-interglacial cycle. Understanding the geometry of a reduced WAIS during intervals when the planet was warmer than present may provide a possible analogue for future environmental conditions given predicted temperature trends. A reduction of WAIS results in rising sea levels which threatens coastal communities across the globe. The data will help improve numerical ice sheet models to better predict WAIS response to current and future climate trends. The project supports a teacher educational workshop and the training of graduate and undergraduate students. The goal of this project is to obtain rock samples from beneath the WAIS through shallow (\u003c80 m) drilling at Mt. Waesche, a volcano in Marie Byrd Land, near an ice dome of WAIS (2000 m elevation). The lithologies of lava flows exposed on the flank of the volcano are well-suited for cosmogenic 3He and 36Cl as well as 40Ar/39Ar measurements which will establish eruption and exposure age. Existing 40Ar/39Ar data indicate basaltic lava flows on the volcano flank as young as 350 ka. Thus, measured cosmogenic nuclides measured in rock cores from beneath the ice surface will be indicative of relatively recent exposure during periods of reduced ice elevation, most likely, during the last interglacial. The first field season is focused on identifying appropriate locations for drilling and a ground penetrating radar (GPR) survey of the subglacial topography \u003c100m under the blue ice area. Mapping and dating the adjacent exposed lava flows will allow tracing of lava flows of known age and composition below the ice margin that will be targeted for drilling the following year. The second field season activities include drilling 8 boreholes (two transects) through blue ice with the Winkie drill near the ice margin to 80 m depth to obtain rock cores from the sub-ice lava flows. 3He exposure ages will constrain the duration and minimum extent of past surface lowering of the WAIS in Marie Byrd Land. Deeper GPR imaging (up to 700 m) will hope to reveal additional evidence of lava/ice interactions that would independently place constraints on lower ice levels during past eruptions. Results from this study will be compared with the modeled ice elevation histories at Mt. Waesche to validate ice sheet modeling efforts. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": -111.0, "geometry": "POINT(-128 -77)", "instruments": null, "is_usap_dc": true, "keywords": "FIELD SURVEYS; Mt. Waesche; USA/NSF; SNOW/ICE; GLACIER THICKNESS/ICE SHEET THICKNESS; PALEOCLIMATE RECONSTRUCTIONS; LABORATORY; LAVA COMPOSITION/TEXTURE; Amd/Us; AMD; USAP-DC", "locations": "Mt. Waesche", "north": -74.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences; Antarctic Earth Sciences", "paleo_time": null, "persons": "Braddock, Scott; Campbell, Seth; Ackert, Robert; Zimmerer, Matthew; Mitrovica, Jerry", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -80.0, "title": "Collaborative Research: Constraining West Antarctic Ice Sheet elevation during the last interglacial", "uid": "p0010272", "west": -145.0}, {"awards": "1542936 Goehring, Brent; 1542976 Balco, Gregory", "bounds_geometry": "POLYGON((-145.7 -64.195,-113.988 -64.195,-82.276 -64.195,-50.564 -64.195,-18.852 -64.195,12.86 -64.195,44.572 -64.195,76.284 -64.195,107.996 -64.195,139.708 -64.195,171.42 -64.195,171.42 -66.2096,171.42 -68.2242,171.42 -70.2388,171.42 -72.2534,171.42 -74.268,171.42 -76.2826,171.42 -78.2972,171.42 -80.3118,171.42 -82.3264,171.42 -84.341,139.708 -84.341,107.996 -84.341,76.284 -84.341,44.572 -84.341,12.86 -84.341,-18.852 -84.341,-50.564 -84.341,-82.276 -84.341,-113.988 -84.341,-145.7 -84.341,-145.7 -82.3264,-145.7 -80.3118,-145.7 -78.2972,-145.7 -76.2826,-145.7 -74.268,-145.7 -72.2534,-145.7 -70.2388,-145.7 -68.2242,-145.7 -66.2096,-145.7 -64.195))", "dataset_titles": "Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom", "datasets": [{"dataset_uid": "200199", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Fri, 03 Sep 2021 00:00:00 GMT", "description": "The overall goal of this project is to determine the effect of past changes in the size of the Antarctic Ice Sheet on global sea level. At the peak of the last ice age 25,000 years ago, sea level was 120 meters (400 feet) lower than it is at present because water that is now part of the ocean was instead part of expanded glaciers and ice sheets in North America, Eurasia, and Antarctica. Between then and now, melting and retreat of this land ice caused sea level to rise. In this project, we aim to improve our understanding of how changes in the size of the Antarctic Ice Sheet contributed to this process. The overall strategy to accomplish this involves (i) visiting areas in Antarctica that are not now covered by ice; (ii) looking for geological evidence, specifically rock surface and sediment deposits, that indicates that these areas were covered by thicker ice in the past; and (iii) determining the age of these geological surfaces and deposits. This project addresses the final part of this strategy -- determining the age of Antarctic glacial rock surfaces or sediment deposits -- using a relatively new technique that involves measuring trace elements in rock surfaces that are produced by cosmic-ray bombardment after the rock surfaces are exposed by ice retreat. By applying this method to rock samples collected in previous visits to Antarctica, the timing of past expansion and contraction of the ice sheet can be determined. The main scientific outcomes expected from this project are (i) improved understanding of how Antarctic Ice Sheet changes contributed to past global sea level rise; and (ii) improved understanding of modern observed Antarctic Ice Sheet changes in a longer-term context. This second outcome will potentially improve predictions of future ice sheet behavior. Other outcomes of the project include training of individual undergraduate and graduate students, as well as the development of a new course on sea level change to be taught at Tulane University in New Orleans, a city that is being affected by sea level change today. This project will use measurements of in-situ-produced cosmogenic carbon-14 in quartz from existing samples collected at several sites in Antarctica to resolve major ambiguities in existing Last Glacial Maximum to present ice sheet reconstructions. This project is important because of the critical nature of accurate reconstructions of ice sheet change in constraining reconstructions of past sea level change. Although carbon-14 is most commonly exploited as a geochronometer through its production in the upper atmosphere and incorporation into organic materials, it is also produced within the crystal lattice of rocks and minerals that are exposed to the cosmic-ray flux at the Earth\u0027s surface. In this latter case, its concentration is proportional to the duration of surface exposure, and measurements of in-situ-produced carbon-14 can be used to date geological events that form or expose rock surfaces, for example, ice sheet expansion and retreat. Although carbon-14 is one of several trace radionuclides that can be used for this purpose, it is unique among them in that its half-life is short relative to the time scale of glacial-interglacial variations. Thus, in cases where rock surfaces in polar regions have been repeatedly covered and uncovered by ice sheet change during many glacial-interglacial cycles, carbon-14 measurements are uniquely suited to accurately dating the most recent episode of ice sheet advance and retreat. We aim to use this property to improve our understanding of Antarctic Ice Sheet change at a number of critically located sites at which other surface exposure dating methods have yielded ambiguous results. Geographically, these are focused in the Weddell Sea embayment of Antarctica, which is an area where the geometry of the Antarctic continent potentially permits large glacial-interglacial changes in ice volume but where existing geologic records of ice sheet change are particularly ambiguous. In addition, in-situ carbon-14 measurements, applied where independently constrained deglaciation chronologies already exist, can potentially allow us to date the last period of ice sheet advance as well as the most recent retreat.", "east": 171.42, "geometry": "POINT(12.86 -74.268)", "instruments": null, "is_usap_dc": true, "keywords": "Amd/Us; Cosmogenic Dating; GLACIER THICKNESS/ICE SHEET THICKNESS; AMD; USAP-DC; GLACIER ELEVATION/ICE SHEET ELEVATION; GLACIERS/ICE SHEETS; Carbon-14; USA/NSF; Weddell Sea Embayment; LABORATORY; FIELD SURVEYS; GLACIATION", "locations": "Weddell Sea Embayment", "north": -64.195, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences", "paleo_time": null, "persons": "Goehring, Brent; Balco, Gregory", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "ICE-D", "repositories": "ICE-D", "science_programs": null, "south": -84.341, "title": "COLLABORATIVE RESEARCH: Resolving Ambiguous Exposure-Age Chronologies of Antarctic Deglaciation with Measurements of In-Situ-Produced Cosmogenic Carbon-14", "uid": "p0010254", "west": -145.7}, {"awards": "2122248 Waters, Laura", "bounds_geometry": "POLYGON((-127.143608 -77.1380528,-127.1012394 -77.1380528,-127.0588708 -77.1380528,-127.0165022 -77.1380528,-126.9741336 -77.1380528,-126.931765 -77.1380528,-126.8893964 -77.1380528,-126.8470278 -77.1380528,-126.8046592 -77.1380528,-126.7622906 -77.1380528,-126.719922 -77.1380528,-126.719922 -77.14809141,-126.719922 -77.15813002,-126.719922 -77.16816863,-126.719922 -77.17820724,-126.719922 -77.18824585,-126.719922 -77.19828446,-126.719922 -77.20832307,-126.719922 -77.21836168,-126.719922 -77.22840029,-126.719922 -77.2384389,-126.7622906 -77.2384389,-126.8046592 -77.2384389,-126.8470278 -77.2384389,-126.8893964 -77.2384389,-126.931765 -77.2384389,-126.9741336 -77.2384389,-127.0165022 -77.2384389,-127.0588708 -77.2384389,-127.1012394 -77.2384389,-127.143608 -77.2384389,-127.143608 -77.22840029,-127.143608 -77.21836168,-127.143608 -77.20832307,-127.143608 -77.19828446,-127.143608 -77.18824585,-127.143608 -77.17820724,-127.143608 -77.16816863,-127.143608 -77.15813002,-127.143608 -77.14809141,-127.143608 -77.1380528))", "dataset_titles": null, "datasets": null, "date_created": "Thu, 19 Aug 2021 00:00:00 GMT", "description": "This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The geologic record reveals that volcanic activity increases when glaciers retreat and major ice sheets thin. This relationship produces a positive feedback mechanism where the uptick in volcanism increases greenhouse gasses concentrations, leading to climate warming and further deglaciation. Although the pattern between volcanism and deglaciation is observed in the geologic record, the exact mechanism(s) by which glaciers impact a volcanic plumbing system is unknown. This project focuses on Mount Waesche, a volcano in West Antarctica, that frequently erupts during warm, interglacial periods and undergoes a period of less activity during cold, glacial periods. This project will examine compositions of the rocks and minerals from Mount Waesche to determine magma storage depths, allowing the investigators to understand how magma plumbing systems change in response to glacial cycles. These results will be compared with geodynamic simulations to understand the physics behind the effects of deglaciation on the magmatic plumbing systems within Earth\u2019s crust. The investigators will additionally partner with Mentoring Kids Works to develop several Polar and Earth Science Educational Modules aimed at improving reading skills in third grade students in New Mexico. The proposed Polar and Earth Science program consists of modules that include readings of books introducing students to Earth and Polar science themes, paired with Earth and Polar Science activities, followed by simple experiments, where students make predictions and collect data. Information required to implement our Polar and Earth Science curriculum will be made available online. Isotopic and sedimentary datasets reveal that volcanic activity typically increases during interglacial periods. However, the physical mechanisms through which changes in the surface loading affect volcanic magmatic plumbing systems remain unconstrained. Recently generated 40Ar/39Ar eruption ages indicate that 86% of the dated samples from Mt. Waesche, a late Quaternary volcano in Marie Byrd land, correlate with interglacial periods, suggesting this volcano uniquely responds to changes in the West Antarctic Ice Sheet. We propose to combine the petrology of Mount Waesche\u2019s volcanic record, constraints on changing ice loads through time, and geodynamic modelling to: (1) Determine how pre-eruptive storage conditions change during glacial and interglacial periods using whole rock and mineral compositions of volcanic rocks; (2) Conduct geodynamic modeling to elucidate the relationship between lithospheric structure, temporal variations in ice sheet thickness, and subsequent changes in crustal stresses and magmatic transport and, therefore, the mechanism(s) by which deglaciation impacts magmatic plumbing systems; (3) Use the outcomes of objectives (1) and (2) to provide new constraints on the changes in ice sheet thickness through time that could plausibly trigger future volcanic and magmatic activity in West Antarctica. This collaborative approach will provide a novel methodology to determine prior magnitudes and rates of ice load changes within the Marie Byrd Land region of Antarctica. Lastly, estimates of WAIS elevation changes from this study will be compared to ongoing studies at Mount Waesche focused on constraining last interglacial ice sheet draw down using cosmogenic exposure ages obtained from shallow drilling. The scope of work also includes a partnership with Mentoring Kids Works to develop several Polar and Earth Science Educational Modules aimed at improving reading skills in third grade students in New Mexico. The proposed Polar and Earth Science program consists of modules that include readings of books introducing students to Earth and Polar science themes, paired with Earth and Polar Science activities, followed by simple experiments, where students make predictions and collect data. Information required to implement our Polar and Earth Science curriculum will be made available online. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": -126.719922, "geometry": "POINT(-126.931765 -77.18824585)", "instruments": null, "is_usap_dc": true, "keywords": "Mt. Waesche; GEOCHEMISTRY; LITHOSPHERIC PLATE MOTION; STRESS; Amd/Us; West Antarctica; Executive Committee Range; NOT APPLICABLE; USAP-DC; AMD; MAJOR ELEMENTS; USA/NSF; ROCKS/MINERALS/CRYSTALS", "locations": "West Antarctica; Mt. Waesche; Executive Committee Range", "north": -77.1380528, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Waters, Laura; Naliboff, John; Zimmerer, Matthew", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repositories": null, "science_programs": null, "south": -77.2384389, "title": "Integrating petrologic records and geodynamics: Quantifying the effects of glaciation on crustal stress and eruptive patterns at Mt. Waesche, Executive Committee Range, Antarctica", "uid": "p0010248", "west": -127.143608}, {"awards": "1443329 Balco, Gregory; 1443321 Bromley, Gordon", "bounds_geometry": "POLYGON((-180 -85.40705,-179.659078 -85.40705,-179.318156 -85.40705,-178.977234 -85.40705,-178.636312 -85.40705,-178.29539 -85.40705,-177.954468 -85.40705,-177.613546 -85.40705,-177.272624 -85.40705,-176.931702 -85.40705,-176.59078 -85.40705,-176.59078 -85.422615,-176.59078 -85.43818,-176.59078 -85.453745,-176.59078 -85.46931,-176.59078 -85.484875,-176.59078 -85.50044,-176.59078 -85.516005,-176.59078 -85.53157,-176.59078 -85.547135,-176.59078 -85.5627,-176.931702 -85.5627,-177.272624 -85.5627,-177.613546 -85.5627,-177.954468 -85.5627,-178.29539 -85.5627,-178.636312 -85.5627,-178.977234 -85.5627,-179.318156 -85.5627,-179.659078 -85.5627,180 -85.5627,179.277561 -85.5627,178.555122 -85.5627,177.832683 -85.5627,177.110244 -85.5627,176.387805 -85.5627,175.665366 -85.5627,174.942927 -85.5627,174.220488 -85.5627,173.498049 -85.5627,172.77561 -85.5627,172.77561 -85.547135,172.77561 -85.53157,172.77561 -85.516005,172.77561 -85.50044,172.77561 -85.484875,172.77561 -85.46931,172.77561 -85.453745,172.77561 -85.43818,172.77561 -85.422615,172.77561 -85.40705,173.498049 -85.40705,174.220488 -85.40705,174.942927 -85.40705,175.665366 -85.40705,176.387805 -85.40705,177.110244 -85.40705,177.832683 -85.40705,178.555122 -85.40705,179.277561 -85.40705,-180 -85.40705))", "dataset_titles": "Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom", "datasets": [{"dataset_uid": "200199", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Sun, 20 Dec 2020 00:00:00 GMT", "description": "This investigation will reconstruct past behavior of the East Antarctic Ice Sheet during periods of warmer-than-present climate, such as the Pliocene, in order to better project the likely response of Earth\u0027s largest ice sheet to anthropogenic warming. Containing the equivalent of ~55 m sea-level rise, the future evolution of the East Antarctic Ice Sheet has clear societal ramifications on a global scale as temperatures continue to rise. Therefore, determining ice-sheet sensitivity to climate on the scale predicted for the next two centuries is a matter of increasing urgency, particularly in light of evidence suggesting the East Antarctic Ice Sheet is more dynamic than previously thought. This research will provide a terrestrial geologic record of long-term ice-sheet behavior from sites immediately adjacent the East Antarctic Ice Sheet in the Transantarctic Mountains, with which the project will help ascertain how the ice sheet responded to past warm periods. The project will focus primarily on the Pliocene warm period, 5 to 3 million years ago, as this represents the closest analogue to 21st Century climate conditions. The proposed research will investigate glacial deposits corresponding to the East Antarctic Ice Sheet in the central Transantarctic Mountains in order to expand the geologic record of past ice-sheet behavior. The overarching research objectives are to improve understanding of the East Antarctic Ice Sheet\u0027s configuration during periods of warmer-than-present climate, such as the Pliocene warm period, and to determine whether the ice sheet underwent significant volume changes or remained relatively stable in response to warming. To address these goals, the investigation will map and date glacial deposits preserved at mountain sites immediately adjacent the ice sheet. Specifically, we will: (i) employ multiple cosmogenic nuclides (10Be, 26Al, 21Ne) to establish more fully ice-thickness histories for the upper Shackleton and Beardmore Glaciers, where they exit the ice sheet; (ii) use this record to identify periods during which the East Antarctic Ice Sheet was at least as extensive as today; and (iii) use these data to assess long-term ice-sheet variability in East Antarctica, with particular emphasis on Pliocene warm episodes. This research will require Antarctic fieldwork, glacial-geologic mapping, and cosmogenic surface-exposure dating.", "east": -176.59078, "geometry": "POINT(178.092415 -85.484875)", "instruments": null, "is_usap_dc": true, "keywords": "Amd/Us; Transantarctic Mountains; GLACIERS/ICE SHEETS; AMD; GLACIER THICKNESS/ICE SHEET THICKNESS; GLACIER ELEVATION/ICE SHEET ELEVATION; NOT APPLICABLE; Antarctica", "locations": "Antarctica; Transantarctic Mountains", "north": -85.40705, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology", "paleo_time": "PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e HOLOCENE; PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e PLEISTOCENE", "persons": "Balco, Gregory; Bromley, Gorden; BROMLEY, GORDON", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "ICE-D", "repositories": "ICE-D", "science_programs": null, "south": -85.5627, "title": "Collaborative Research: Potential Direct Geologic Constraint of Ice Sheet Thickness in the Central Transantarctic Mountains during the Pliocene Warm Period", "uid": "p0010153", "west": 172.77561}, {"awards": "0838256 Todd, Claire; 0838784 Balco, Gregory; 0838783 Conway, Howard", "bounds_geometry": "POLYGON((-66.27517 -83.23921,-65.341961 -83.23921,-64.408752 -83.23921,-63.475543 -83.23921,-62.542334 -83.23921,-61.609125 -83.23921,-60.675916 -83.23921,-59.742707 -83.23921,-58.809498 -83.23921,-57.876289 -83.23921,-56.94308 -83.23921,-56.94308 -83.359865,-56.94308 -83.48052,-56.94308 -83.601175,-56.94308 -83.72183,-56.94308 -83.842485,-56.94308 -83.96314,-56.94308 -84.083795,-56.94308 -84.20445,-56.94308 -84.325105,-56.94308 -84.44576,-57.876289 -84.44576,-58.809498 -84.44576,-59.742707 -84.44576,-60.675916 -84.44576,-61.609125 -84.44576,-62.542334 -84.44576,-63.475543 -84.44576,-64.408752 -84.44576,-65.341961 -84.44576,-66.27517 -84.44576,-66.27517 -84.325105,-66.27517 -84.20445,-66.27517 -84.083795,-66.27517 -83.96314,-66.27517 -83.842485,-66.27517 -83.72183,-66.27517 -83.601175,-66.27517 -83.48052,-66.27517 -83.359865,-66.27517 -83.23921))", "dataset_titles": "Interface to observational data collected in this project and geologic age information derived therefrom. Dynamic content, continuously updated.; Web page linking to documents containing data collected in this project. Static content", "datasets": [{"dataset_uid": "200195", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Web page linking to documents containing data collected in this project. Static content", "url": "http://noblegas.berkeley.edu/~balcs/pensacola/"}, {"dataset_uid": "200194", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Interface to observational data collected in this project and geologic age information derived therefrom. Dynamic content, continuously updated.", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Sat, 19 Dec 2020 00:00:00 GMT", "description": "This award supports a project to find and date geologic evidence of past ice-marginal positions in the Pensacola Mountains, which border the Foundation Ice Stream at the head of the Weddell Sea embayment. The project will involve glacial geologic mapping and cosmogenic-nuclide surface exposure dating of glacially transported erratics. An ice-flow model will be used to link our exposure-dating results together in a glaciologically consistent way, and to relate them to regional LGM to Holocene elevation changes. A secondary focus of the project seeks to improve the effectiveness of exposure-dating methods in understanding ice sheet change. Changes in the location of the ice margin, and thus the exposure ages that record these changes, are controlled not only by regional ice sheet mass balance, but also by local effects on snow- and icefields immediately adjacent to the exposure-dating sites. This part of the project will combine glaciological observations near the present ice margin with targeted exposure- age sampling in an effort to better understand the processes controlling the ice margin location, and improve the interpretation of very recent exposure-age data as a record of latest Holocene to present ice sheet changes. The intellectual merit of the project is that it will provide direct geologic evidence of LGM-to-Holocene ice volume change in a region of Antarctica where no such evidence now exists. The broader impacts of the work involve both gathering information needed for accurate understanding of past and present global sea level change. Secondly, this project will help to develop and maintain the human and intellectual resources necessary for continued excellence in polar research and global change education, by linking experienced Antarctic researchers with early career scientists who seek to develop their expertise in both research and education. In addition, it brings together two early career scientists whose careers are focused at opposite ends of the research-education spectrum, thus facilitating better integration of research and education both in the careers of these scientists and in the outcome of this project. This award has field work in Antarctica.", "east": -56.94308, "geometry": "POINT(-61.609125 -83.842485)", "instruments": null, "is_usap_dc": true, "keywords": "GLACIERS/ICE SHEETS; GLACIER THICKNESS/ICE SHEET THICKNESS; NOT APPLICABLE; GLACIER ELEVATION/ICE SHEET ELEVATION; Antarctica", "locations": "Antarctica", "north": -83.23921, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology; Antarctic Glaciology", "paleo_time": "PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e HOLOCENE; PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e PLEISTOCENE", "persons": "Balco, Gregory; Todd, Claire; Conway, Howard", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "PI website", "repositories": "ICE-D; PI website", "science_programs": null, "south": -84.44576, "title": "Collaborative Research: Last Glacial Maximum and Deglaciation Chronology for the Foundation Ice Stream and Southeastern Weddell Sea Embayment", "uid": "p0010151", "west": -66.27517}, {"awards": "1443433 Licht, Kathy; 1443213 Kaplan, Michael", "bounds_geometry": "POLYGON((159 -83.8,159.5 -83.8,160 -83.8,160.5 -83.8,161 -83.8,161.5 -83.8,162 -83.8,162.5 -83.8,163 -83.8,163.5 -83.8,164 -83.8,164 -83.87,164 -83.94,164 -84.01,164 -84.08,164 -84.15,164 -84.22,164 -84.29,164 -84.36,164 -84.43,164 -84.5,163.5 -84.5,163 -84.5,162.5 -84.5,162 -84.5,161.5 -84.5,161 -84.5,160.5 -84.5,160 -84.5,159.5 -84.5,159 -84.5,159 -84.43,159 -84.36,159 -84.29,159 -84.22,159 -84.15,159 -84.08,159 -84.01,159 -83.94,159 -83.87,159 -83.8))", "dataset_titles": "10Be and 26Al cosmogenic nuclide surface exposure data; 3He input data", "datasets": [{"dataset_uid": "601376", "doi": "10.15784/601376", "keywords": "Antarctica; Transantarctic Mountains", "people": "Kaplan, Michael; Winckler, Gisela; Schaefer, Joerg", "repository": "USAP-DC", "science_program": null, "title": "3He input data", "url": "https://www.usap-dc.org/view/dataset/601376"}, {"dataset_uid": "601375", "doi": "10.15784/601375", "keywords": "Antarctica; Cosmogenic Dating; Transantarctic Mountains", "people": "Kaplan, Michael; Schaefer, Joerg; Winckler, Gisela", "repository": "USAP-DC", "science_program": null, "title": "10Be and 26Al cosmogenic nuclide surface exposure data", "url": "https://www.usap-dc.org/view/dataset/601375"}], "date_created": "Tue, 29 Sep 2020 00:00:00 GMT", "description": "Licht/1443433 Sediments deposited by the Antarctic ice sheet are an archive of its history with time and help geologists to determine how the remote interior of the ice sheet has changed over the past several hundred thousand years. This project will focus on the formation and dynamics of moraines (accumulations of dirt and rocks that are incorporated in the glacier surface or have been pushed along by the glacier as it moves) near the blue ice area of Mt. Achernar in the central Transantarctic Mountains in Antarctica.. The study will improve basic understanding of the formation of these moraines. Fieldwork at the site will focus on imaging the internal structure of the moraine to determine the processes by which it, and others like it, form over time. Additional analyses will include measurements of ice flow and collection of rock samples to determine the timing of debris deposition and the changes in the sources of sediments from deep within the Antarctic continent. The project will provide both graduate and undergraduate students training in paleoclimate studies, geology, and numerical modeling approaches. The broader impacts of the proposed work include hands on training in the Earth Sciences for graduate and undergraduate students, collaboration with colleagues in New Zealand and Sweden to provide an international research experience for students from the US, and three educational modules to be delivered by student researchers regarding Antarctica\u0027s role in global environments. The research is societally relevant and multidisciplinary and the topics are ideal for sharing with the public. All research findings will be made publicly available to others via timely publication in high-impact, peer-reviewed journals and all data will be submitted to the National Snow and Ice Data Center, and excess samples will be provided to the U.S. Polar Rock Repository. Direct observations of ice sheet history from the margins of Antarctica\u0027s polar plateau are essential for testing numerical ice sheet models, and the laterally extensive, blue-ice moraines of the Mt. Achernar Moraine complex in the central Transantarctic Mountains contain a unique and nearly untapped direct, quasi-continuous record of ice sheet change over multiple glacial cycles. The project objectives include improved understanding of processes and rates of blue ice moraine formation, as well as identifying the topographic, glaciological, and climatic controls on their evolution. Data to be collected with fieldwork in Antarctica include: imaging of internal ice structure with ground-penetrating radar, measurement of ice flow velocity and direction with a global positioning system (GPS) array, analysis of debris concentration and composition in glacier ice, state-of-the-art cosmogenic multi-nuclide analyses to determine exposure ages of moraine debris, mapping of trimlines and provenance analysis. Numerical model simulations, constrained by field data, will be used to evaluate the factors influencing changes in glacier flow that potentially impact the accumulation of the moraine debris. All together, the new data and modeling efforts will improve conceptual models of blue ice moraine formation, and thereby make them a more valuable proxy for developing a better understanding of the history of the ice sheet.", "east": 164.0, "geometry": "POINT(161.5 -84.15)", "instruments": null, "is_usap_dc": true, "keywords": "SEDIMENTS; GLACIAL PROCESSES; Mt. Achernar; ABLATION ZONES/ACCUMULATION ZONES; GLACIER ELEVATION/ICE SHEET ELEVATION; Antarctica; Antarctic Ice Sheet; Transantarctic Mountains; GLACIATION; USAP-DC; ICE MOTION; AMD; LABORATORY; Amd/Us", "locations": "Transantarctic Mountains; Antarctic Ice Sheet; Mt. Achernar; Antarctica", "north": -83.8, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Glaciology; Antarctic Glaciology; Antarctic Earth Sciences", "paleo_time": null, "persons": "Kaplan, Michael; Schaefer, Joerg; Winckler, Gisela; Licht, Kathy", "platforms": "OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.5, "title": "Collaborative Research: Multidisciplinary Analysis of Antarctic Blue Ice Moraine Formation and their Potential as Climate Archives over Multiple Glacial Cycles", "uid": "p0010131", "west": 159.0}, {"awards": "9615282 Siddoway, Christine; 9615281 Luyendyk, Bruce", "bounds_geometry": "POLYGON((-170 -76,-166.5 -76,-163 -76,-159.5 -76,-156 -76,-152.5 -76,-149 -76,-145.5 -76,-142 -76,-138.5 -76,-135 -76,-135 -76.8,-135 -77.6,-135 -78.4,-135 -79.2,-135 -80,-135 -80.8,-135 -81.6,-135 -82.4,-135 -83.2,-135 -84,-138.5 -84,-142 -84,-145.5 -84,-149 -84,-152.5 -84,-156 -84,-159.5 -84,-163 -84,-166.5 -84,-170 -84,-170 -83.2,-170 -82.4,-170 -81.6,-170 -80.8,-170 -80,-170 -79.2,-170 -78.4,-170 -77.6,-170 -76.8,-170 -76))", "dataset_titles": "Bedrock sample data, Ford Ranges region (Marie Byrd Land); SOAR-WMB Airborne gravity data", "datasets": [{"dataset_uid": "601294", "doi": "10.15784/601294", "keywords": "Aerogeophysics; Airborne Gravity; Airplane; Antarctica; Free Air Gravity; Glaciers/ice Sheet; Glaciers/Ice Sheet; Gravimeter; Gravity; Gravity Data; Marie Byrd Land; Potential Field; Ross Sea; Solid Earth", "people": "Bell, Robin", "repository": "USAP-DC", "science_program": null, "title": "SOAR-WMB Airborne gravity data", "url": "https://www.usap-dc.org/view/dataset/601294"}, {"dataset_uid": "601829", "doi": "10.15784/601829", "keywords": "Antarctica; Cryosphere; Gondwana; Marie Byrd Land; Migmatite", "people": "Siddoway, Christine", "repository": "USAP-DC", "science_program": null, "title": "Bedrock sample data, Ford Ranges region (Marie Byrd Land)", "url": "https://www.usap-dc.org/view/dataset/601829"}], "date_created": "Fri, 24 Apr 2020 00:00:00 GMT", "description": "OPP 9615281 Luyendyk OPP 9615282 Siddoway Abstract This award supports a collaborative project that combines air and ground geological-geophysical investigations to understand the tectonic and geological development of the boundary between the Ross Sea Rift and the Marie Byrd Land (MBL) volcanic province. The project will determine the Cenozoic tectonic history of the region and whether Neogene structures that localized outlet glacier flow developed within the context of Cenozoic rifting on the eastern Ross Embayment margin, or within the volcanic province in MBL. The geological structure at the boundary between the Ross Embayment and western MBL may be a result of: 1) Cenozoic extension on the eastern shoulder of the Ross Sea rift; 2) uplift and crustal extension related to Neogene mantle plume activity in western MBL; or a combination of the two. Faulting and volcanism, mountain uplift, and glacier downcutting appear to now be active in western MBL, where generally East-to-West-flowing outlet glaciers incise Paleozoic and Mesozoic bedrock, and deglaciated summits indicate a previous North-South glacial flow direction. This study requires data collection using SOAR (Support Office for Aerogeophysical Research, a facility supported by Office of Polar Programs which utilizes high precision differential GPS to support a laser altimeter, ice-penetrating radar, a towed proton magnetometer, and a Bell BGM-3 gravimeter). This survey requires data for 37,000 square kilometers using 5.3 kilometer line spacing with 15.6 kilometer tie lines, and 86,000 square kilometers using a grid of 10.6 by 10.6 kilometer spacing. Data will be acquired over several key features in the region including, among other, the eastern edge of the Ross Sea rift, over ice stream OEO, the transition from the Edward VII Peninsula plateau to the Ford Ranges, the continuation to the east of a gravity high known from previous reconnaissance mapping over the Fosdick Metamorphic Complex, an d the extent of the high-amplitude magnetic anomalies (volcanic centers?) detected southeast of the northern Ford Ranges by other investigators. SOAR products will include glaciology data useful for studying driving stresses, glacial flow and mass balance in the West Antarctic Ice Sheet (WAIS). The ground program is centered on the southern Ford Ranges. Geologic field mapping will focus on small scale brittle structures for regional kinematic interpretation, on glaciated surfaces and deposits, and on datable volcanic rocks for geochronologic control. The relative significance of fault and joint sets, the timing relationships between them, and the probable context of their formation will also be determined. Exposure ages will be determined for erosion surfaces and moraines. Interpretation of potential field data will be aided by on ground sampling for magnetic properties and density as well as ground based gravity measurements. Oriented samples will be taken for paleomagnetic studies. Combined airborne and ground investigations will obtain basic data for describing the geology and structure at the eastern boundary of the Ross Embayment both in outcrop and ice covered areas, and may be used to distinguish between Ross Sea rift- related structural activity from uplift and faulting on the perimeter of the MBL dome and volcanic province. Outcrop geology and structure will be extrapolated with the aerogeophysical data to infer the geology that resides beneath the WAIS. The new knowledge of Neogene tectonics in western MBL will contribute to a comprehensive model for the Cenozoic Ross rift and to understanding of the extent of plume activity in MBL. Both are important for determining the influence of Neogene tectonics on the ice streams and WAIS.", "east": -135.0, "geometry": "POINT(-152.5 -80)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e LGS", "is_usap_dc": true, "keywords": "GRAVITY; USAP-DC; Ross Sea; TECTONICS; Marie Byrd Land", "locations": "Ross Sea; Marie Byrd Land", "north": -76.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences", "paleo_time": null, "persons": "Luyendyk, Bruce P.; Siddoway, Christine", "platforms": null, "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.0, "title": "Air-Ground Study of Tectonics at the Boundary Between the Eastern Ross Embayment and Western Marie Byrd Land, Antarctica: Basement Geology and Structure", "uid": "p0010096", "west": -170.0}, {"awards": "1443248 Hall, Brenda; 1443346 Stone, John", "bounds_geometry": "POLYGON((-174 -84.2,-172.4 -84.2,-170.8 -84.2,-169.2 -84.2,-167.6 -84.2,-166 -84.2,-164.4 -84.2,-162.8 -84.2,-161.2 -84.2,-159.6 -84.2,-158 -84.2,-158 -84.36,-158 -84.52,-158 -84.68,-158 -84.84,-158 -85,-158 -85.16,-158 -85.32,-158 -85.48,-158 -85.64,-158 -85.8,-159.6 -85.8,-161.2 -85.8,-162.8 -85.8,-164.4 -85.8,-166 -85.8,-167.6 -85.8,-169.2 -85.8,-170.8 -85.8,-172.4 -85.8,-174 -85.8,-174 -85.64,-174 -85.48,-174 -85.32,-174 -85.16,-174 -85,-174 -84.84,-174 -84.68,-174 -84.52,-174 -84.36,-174 -84.2))", "dataset_titles": "Cosmogenic nuclide data from glacial deposits along the Liv Glacier coast; Ice-D Antarctic Cosmogenic Nuclide database - site DUNCAN; Ice-D Antarctic Cosmogenic Nuclide database - site MAASON; Liv and Amundsen Glacier Radiocarbon Data", "datasets": [{"dataset_uid": "200088", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Ice-D Antarctic Cosmogenic Nuclide database - site DUNCAN", "url": "https://version2.ice-d.org/antarctica/nsf/"}, {"dataset_uid": "601208", "doi": "10.15784/601208", "keywords": "Antarctica; Carbon; Glaciology; Holocene; Radiocarbon; Ross Embayment; Ross Sea; Transantarctic Mountains", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Liv and Amundsen Glacier Radiocarbon Data", "url": "https://www.usap-dc.org/view/dataset/601208"}, {"dataset_uid": "601226", "doi": "10.15784/601226", "keywords": "Antarctica; Be-10; Beryllium-10; Cosmogenic; Cosmogenic Dating; Cosmogenic Radionuclides; Deglaciation; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Liv Glacier; Rocks; Ross Ice Sheet; Surface Exposure Dates; Transantarctic Mountains", "people": "Stone, John", "repository": "USAP-DC", "science_program": null, "title": "Cosmogenic nuclide data from glacial deposits along the Liv Glacier coast", "url": "https://www.usap-dc.org/view/dataset/601226"}, {"dataset_uid": "200087", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Ice-D Antarctic Cosmogenic Nuclide database - site MAASON", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Thu, 05 Sep 2019 00:00:00 GMT", "description": "The response of the Antarctic Ice Sheet to future climatic changes is recognized as the greatest uncertainty in projections of future sea level. An understanding of past ice fluctuations affords insight into ice-sheet response to climate and sea-level change and thus is critical for improving sea-level predictions. This project will examine deglaciation of the southern Ross Sea over the past few thousand years to document oscillations in Antarctic ice volume during a period of relatively stable climate and sea level. We will help quantify changes in ice volume, improve understanding of the ice dynamics responsible, and examine the implications for future sea-level change. The project will train future scientists through participation of graduate students, as well as undergraduates who will develop research projects in our laboratories. Previous research indicates rapid Ross Sea deglaciation as far south as Beardmore Glacier early in the Holocene epoch (which began approximately 11,700 years before present), followed by more gradual recession. However, deglaciation in the later half of the Holocene remains poorly constrained, with no chronological control on grounding-line migration between Beardmore and Scott Glaciers. Thus, we do not know if mid-Holocene recession drove the grounding line rapidly back to its present position at Scott Glacier, or if the ice sheet withdrew gradually in the absence of significant climate forcing or eustatic sea level change. The latter possibility raises concerns for future stability of the Ross Sea grounding line. To address this question, we will map and date glacial deposits on coastal mountains that constrain the thinning history of Liv and Amundsen Glaciers. By extending our chronology down to the level of floating ice at the mouths of these glaciers, we will date their thinning history from glacial maximum to present, as well as migration of the Ross Sea grounding line southwards along the Transantarctic Mountains. High-resolution dating will come from Beryllium-10 surface-exposure ages of erratics collected along elevation transects, as well as Carbon-14 dates of algae within shorelines from former ice-dammed ponds. Sites have been chosen specifically to allow close comparison of these two dating methods, which will afford constraints on Antarctic Beryllium-10 production rates.", "east": -158.0, "geometry": "POINT(-166 -85)", "instruments": "NOT APPLICABLE \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "is_usap_dc": true, "keywords": "GLACIERS/ICE SHEETS; NOT APPLICABLE; Antarctica; ICE SHEETS; USAP-DC", "locations": "Antarctica", "north": -84.2, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology", "paleo_time": null, "persons": "Hall, Brenda; Stone, John", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "ICE-D", "repositories": "ICE-D; USAP-DC", "science_programs": null, "south": -85.8, "title": "Collaborative Research: High-resolution Reconstruction of Holocene Deglaciation in the Southern Ross Embayment", "uid": "p0010053", "west": -174.0}, {"awards": "1246110 Stone, John; 1246170 Hall, Brenda", "bounds_geometry": "POLYGON((154 -79.75,154.7 -79.75,155.4 -79.75,156.1 -79.75,156.8 -79.75,157.5 -79.75,158.2 -79.75,158.9 -79.75,159.6 -79.75,160.3 -79.75,161 -79.75,161 -79.8,161 -79.85,161 -79.9,161 -79.95,161 -80,161 -80.05,161 -80.1,161 -80.15,161 -80.2,161 -80.25,160.3 -80.25,159.6 -80.25,158.9 -80.25,158.2 -80.25,157.5 -80.25,156.8 -80.25,156.1 -80.25,155.4 -80.25,154.7 -80.25,154 -80.25,154 -80.2,154 -80.15,154 -80.1,154 -80.05,154 -80,154 -79.95,154 -79.9,154 -79.85,154 -79.8,154 -79.75))", "dataset_titles": "Darwin and Hatherton Glaciers; Hatherton Glacier Radiocarbon Data", "datasets": [{"dataset_uid": "200038", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Darwin and Hatherton Glaciers", "url": "https://version2.ice-d.org/antarctica/nsf/"}, {"dataset_uid": "601063", "doi": "10.15784/601063", "keywords": "Antarctica; Geochronology; Hatherton Glacier; Radiocarbon; Sample/collection Description; Sample/Collection Description; Transantarctic Mountains", "people": "Hall, Brenda", "repository": "USAP-DC", "science_program": null, "title": "Hatherton Glacier Radiocarbon Data", "url": "https://www.usap-dc.org/view/dataset/601063"}], "date_created": "Mon, 23 Oct 2017 00:00:00 GMT", "description": "Hall/1246170 This award supports a project to reconstruct past ice-surface elevations from detailed glacial mapping and dating of moraines (using 14C dates of algae from former ice-marginal ponds and 10Be surface exposure ages) in the region of the Darwin-Hatherton Glaciers in Antarctica in order to try and resolve very different interpretations that currently exist about the glacial history in the region. The results will be integrated with existing climate and geophysical data into a flow-line model to gain insight into glacier response to climate and ice-dynamics perturbations during the Late Glacial Maximum (LGM) in Antarctica. The work will contribute to a better understanding of both LGM ice thickness and whether or not there is any evidence that Antarctica contributed to Meltwater Pulse (MWP)-1A a very controversial topic in Antarctic glacial geology. The intellectual merit of the work relates to the fact that reconstructing past fluctuations of the Antarctic Ice Sheet (AIS) is critical for understanding the sensitivity of ice volume to sea-level and climatic change. Constraints on past behavior help put ongoing changes into context and provide a basis for predicting future sea-level rise. Broader impacts include the support of two graduate and two undergraduate students, as well as a female early-career investigator. Graduate students will be involved in all stages of the project from planning and field mapping to geochronological analyses, interpretation, synthesis and reporting. Two undergraduates will work on lab-based research from the project. The project also will include visits to K-12 classrooms to talk about glaciers and climate change, correspondence with teachers and students from the field, and web-based outreach. This award has field work in Antarctica.", "east": 161.0, "geometry": "POINT(157.5 -80)", "instruments": "NOT APPLICABLE \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "is_usap_dc": true, "keywords": "GLACIERS/ICE SHEETS; FIELD INVESTIGATION; Antarctica", "locations": "Antarctica", "north": -79.75, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology", "paleo_time": null, "persons": "Hall, Brenda; Stone, John; Conway, Howard", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repo": "ICE-D", "repositories": "ICE-D; USAP-DC", "science_programs": null, "south": -80.25, "title": "Collaborative Research: Assessing the Antarctic Contribution to Sea-level Changes during the Last Deglaciation: Constraints from Darwin Glacier", "uid": "p0000304", "west": 154.0}, {"awards": "1460449 Goehring, Brent; 1341420 Balco, Gregory; 1341364 Todd, Claire", "bounds_geometry": "POLYGON((164.08 -74.6,164.0842 -74.6,164.0884 -74.6,164.0926 -74.6,164.0968 -74.6,164.101 -74.6,164.1052 -74.6,164.1094 -74.6,164.1136 -74.6,164.1178 -74.6,164.122 -74.6,164.122 -74.6023,164.122 -74.6046,164.122 -74.6069,164.122 -74.6092,164.122 -74.6115,164.122 -74.6138,164.122 -74.6161,164.122 -74.6184,164.122 -74.6207,164.122 -74.623,164.1178 -74.623,164.1136 -74.623,164.1094 -74.623,164.1052 -74.623,164.101 -74.623,164.0968 -74.623,164.0926 -74.623,164.0884 -74.623,164.0842 -74.623,164.08 -74.623,164.08 -74.6207,164.08 -74.6184,164.08 -74.6161,164.08 -74.6138,164.08 -74.6115,164.08 -74.6092,164.08 -74.6069,164.08 -74.6046,164.08 -74.6023,164.08 -74.6))", "dataset_titles": "Interface to observational data associated with exposure-age measurements and resulting calculated ages. Dynamic content, updated.", "datasets": [{"dataset_uid": "200196", "doi": null, "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Interface to observational data associated with exposure-age measurements and resulting calculated ages. Dynamic content, updated.", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Wed, 18 Oct 2017 00:00:00 GMT", "description": "The investigators will map glacial deposits and date variations in glacier variability at several ice-free regions in northern Victoria Land, Antarctica. These data will constrain the nature and timing of past ice thickness changes for major glaciers that drain into the northwestern Ross Sea. This is important because during the Last Glacial Maximum (15,000 - 18,000 years ago) these glaciers were most likely flowing together with grounded ice from both the East and West Antarctic Ice Sheets that expanded across the Ross Sea continental shelf to near the present shelf edge. Thus, the thickness of these glaciers was most likely controlled in part by the extent and thickness of the Ross Sea ice sheet and ice shelf. The data the PIs propose to collect can provide constraints on the position of the grounding line in the western Ross Sea during the Last Glacial Maximum, the time that position was reached, and ice thickness changes that occurred after that time. The primary intellectual merit of this project will be to improve understanding of a period of Antarctic ice sheet history that is relatively unconstrained at present and also potentially important in understanding past ice sheet-sea level interactions. This proposal will support an early career researcher\u0027s ongoing program of undergraduate education and research that is building a socio-economically diverse student body with students from backgrounds underrepresented in the geosciences. This proposal will also bring an early career researcher into Antarctic research.", "east": 164.122, "geometry": "POINT(164.101 -74.6115)", "instruments": null, "is_usap_dc": true, "keywords": "AMD; Cosmogenic Dating; Exposure Age; LABORATORY; NOT APPLICABLE; Amd/Us; Ross Sea", "locations": "Ross Sea", "north": -74.6, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences; Antarctic Glaciology; Antarctic Earth Sciences; Antarctic Glaciology", "paleo_time": "PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e HOLOCENE; PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e PLEISTOCENE", "persons": "Goehring, Brent; Balco, Gregory; Todd, Claire", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "ICE-D", "repositories": "ICE-D", "science_programs": null, "south": -74.623, "title": "Collaborative Research: Terrestrial Exposure-Age Constraints on the last Glacial Maximum Extent of the Antarctic Ice Sheet in the Western Ross Sea", "uid": "p0000306", "west": 164.08}, {"awards": "1043724 Swanger, Kate", "bounds_geometry": "POLYGON((160.3 -77.4,160.52 -77.4,160.74 -77.4,160.96 -77.4,161.18 -77.4,161.4 -77.4,161.62 -77.4,161.84 -77.4,162.06 -77.4,162.28 -77.4,162.5 -77.4,162.5 -77.44,162.5 -77.48,162.5 -77.52,162.5 -77.56,162.5 -77.6,162.5 -77.64,162.5 -77.68,162.5 -77.72,162.5 -77.76,162.5 -77.8,162.28 -77.8,162.06 -77.8,161.84 -77.8,161.62 -77.8,161.4 -77.8,161.18 -77.8,160.96 -77.8,160.74 -77.8,160.52 -77.8,160.3 -77.8,160.3 -77.76,160.3 -77.72,160.3 -77.68,160.3 -77.64,160.3 -77.6,160.3 -77.56,160.3 -77.52,160.3 -77.48,160.3 -77.44,160.3 -77.4))", "dataset_titles": null, "datasets": null, "date_created": "Sat, 05 Dec 2015 00:00:00 GMT", "description": "Intellectual Merit: The PIs propose to investigate the impact of earth surface processes on the application of cosmogenic exposure dating in Antarctica by combining multi-nuclide techniques, detailed field experiments, rock-mechanic studies, and climate modeling. They will analyze cosmogenic-nuclide inventories for a suite of six alpine-moraine systems in inland regions of the McMurdo Dry Valleys. This area is ideally suited for this study because 1) the targeted alpine moraine sequences are critically important in helping to reconstruct past temperature and precipitation values over the last several million years, 2) the production rates for cosmogenic nuclides are typically high and well-known, and 3) the complexity of surface processes is relatively low. Their work has two specific goals: to evaluate the effects of episodic geomorphic events in modulating cosmogenic inventories in surface rocks in polar deserts and to generate an alpine glacier chronology that will serve as a robust record of regional climate variation over the last several million years. A key objective is to produce a unique sampling strategy that yields consistent exposure-age results by minimizing the effects of episodic geomorphic events that obfuscate cosmogenic-nuclide chronologies. They will link their moraine chronology with regional-scale atmospheric models developed by collaborators at University of Massachusetts Amherst. Broader impacts: This research is interdisciplinary and includes two early career scientists. Results of this work will be used to enhance undergraduate education by engaging two female students in Antarctic field and summer research projects. Extended outreach includes development of virtual Antarctic field trips for Colgate University?s Ho Tung Visualization Laboratory and Boston University?s Antarctic Digital Image Analyses Laboratory. The PIs will continue to work with the Los Angeles Valley Community College, which serves students of mostly Hispanic origin as part of the PolarTREC program. This project will contribute to the collaboration between LDEO and several New York City public high schools within the Lamont-Doherty Secondary School Field Program.", "east": 162.5, "geometry": "POINT(161.4 -77.6)", "instruments": null, "is_usap_dc": true, "keywords": "Not provided", "locations": null, "north": -77.4, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Swanger, Kate", "platforms": "Not provided", "repositories": null, "science_programs": null, "south": -77.8, "title": "Collaborative Research: Multi-nuclide approach to systematically evaluate the scatter in surface exposure ages in Antarctica and to develop consistent alpine glacier chronologies", "uid": "p0000406", "west": 160.3}, {"awards": "1043706 Marchant, David", "bounds_geometry": "POLYGON((160 -76.5,160.45 -76.5,160.9 -76.5,161.35 -76.5,161.8 -76.5,162.25 -76.5,162.7 -76.5,163.15 -76.5,163.6 -76.5,164.05 -76.5,164.5 -76.5,164.5 -76.7,164.5 -76.9,164.5 -77.1,164.5 -77.3,164.5 -77.5,164.5 -77.7,164.5 -77.9,164.5 -78.1,164.5 -78.3,164.5 -78.5,164.05 -78.5,163.6 -78.5,163.15 -78.5,162.7 -78.5,162.25 -78.5,161.8 -78.5,161.35 -78.5,160.9 -78.5,160.45 -78.5,160 -78.5,160 -78.3,160 -78.1,160 -77.9,160 -77.7,160 -77.5,160 -77.3,160 -77.1,160 -76.9,160 -76.7,160 -76.5))", "dataset_titles": null, "datasets": null, "date_created": "Fri, 23 Oct 2015 00:00:00 GMT", "description": "Intellectual Merit: The PIs propose to investigate the impact of earth surface processes on the application of cosmogenic exposure dating in Antarctica by combining multi-nuclide techniques, detailed field experiments, rock-mechanic studies, and climate modeling. They will analyze cosmogenic-nuclide inventories for a suite of six alpine-moraine systems in inland regions of the McMurdo Dry Valleys. This area is ideally suited for this study because 1) the targeted alpine moraine sequences are critically important in helping to reconstruct past temperature and precipitation values over the last several million years, 2) the production rates for cosmogenic nuclides are typically high and well-known, and 3) the complexity of surface processes is relatively low. Their work has two specific goals: to evaluate the effects of episodic geomorphic events in modulating cosmogenic inventories in surface rocks in polar deserts and to generate an alpine glacier chronology that will serve as a robust record of regional climate variation over the last several million years. A key objective is to produce a unique sampling strategy that yields consistent exposure-age results by minimizing the effects of episodic geomorphic events that obfuscate cosmogenic-nuclide chronologies. They will link their moraine chronology with regional-scale atmospheric models developed by collaborators at University of Massachusetts Amherst. Broader impacts: This research is interdisciplinary and includes two early career scientists. Results of this work will be used to enhance undergraduate education by engaging two female students in Antarctic field and summer research projects. Extended outreach includes development of virtual Antarctic field trips for Colgate University?s Ho Tung Visualization Laboratory and Boston University?s Antarctic Digital Image Analyses Laboratory. The PIs will continue to work with the Los Angeles Valley Community College, which serves students of mostly Hispanic origin as part of the PolarTREC program. This project will contribute to the collaboration between LDEO and several New York City public high schools within the Lamont-Doherty Secondary School Field Program.", "east": 164.5, "geometry": "POINT(162.25 -77.5)", "instruments": null, "is_usap_dc": false, "keywords": "McMurdo Dry Valleys; Rock Weathering; Not provided", "locations": "McMurdo Dry Valleys", "north": -76.5, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Marchant, David", "platforms": "Not provided", "repositories": null, "science_programs": null, "south": -78.5, "title": "Collaborative Research: Multi-nuclide approach to systematically evaluate the scatter in surface exposure ages in Antarctica and to develop consistent alpine glacier chronologies", "uid": "p0000269", "west": 160.0}, {"awards": "0229314 Stone, John", "bounds_geometry": null, "dataset_titles": "Reedy Glacier Exposure Ages, Antarctica", "datasets": [{"dataset_uid": "609601", "doi": "10.7265/N5MG7MF1", "keywords": "Antarctica; Chemistry:rock; Chemistry:Rock; Cosmogenic; Geochemistry; Geochronology; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Reedy Glacier; Sample/collection Description; Sample/Collection Description", "people": "Stone, John", "repository": "USAP-DC", "science_program": null, "title": "Reedy Glacier Exposure Ages, Antarctica", "url": "https://www.usap-dc.org/view/dataset/609601"}], "date_created": "Mon, 30 Mar 2015 00:00:00 GMT", "description": "The stability of the marine West Antarctic Ice Sheet (WAIS) remains an important, unresolved problem for predicting future sea level change. Recent studies indicate that the mass balance of the ice sheet today may be negative or positive. The apparent differences may stem in part from short-term fluctuations in flow. By comparison, geologic observations provide evidence of behavior over much longer time scales. Recent work involving glacial-geologic mapping, dating and ice-penetrating radar surveys suggests that deglaciation of both the Ross Sea Embayment and coastal Marie Byrd Land continued into the late Holocene, and leaves open the possibility of ongoing deglaciation and grounding-line retreat. However, previous work in the Ross Sea Embayment was based on data from just three locations that are all far to the north of the present grounding line. Additional data from farther south in the Ross Sea Embayment are needed to investigate whether recession has ended, or if the rate and pattern of deglaciation inferred from our previous study still apply to the present grounding line. This award provides support to reconstruct the evolution of Reedy Glacier, in the southern Transantarctic Mountains, since the Last Glacial Maximum (LGM). Because Reedy Glacier emerges from the mountains above the grounding line, its surface slope and elevation should record changes in thickness of grounded ice in the Ross Sea up to the present day. The deglaciation chronology of Reedy Glacier therefore can indicate whether Holocene retreat of the WAIS ended thousands of years ago, or is still continuing at present. This integrated glaciologic, glacial-geologic, and cosmogenic-isotope exposure- dating project will reconstruct past levels of Reedy Glacier. Over two field seasons, moraines will be mapped, dated and correlated at sites along the length of the glacier. Radar and GPS measurements will be made to supplement existing ice thickness and velocity data, which are needed as input for a model of glacier dynamics. The model will be used to relate geologic measurements to the grounding-line position downstream. Ultimately, the mapping, dating and ice-modeling components of the study will be integrated into a reconstruction that defines changes in ice thickness in the southern Ross Sea since the LGM, and relates these changes to the history of grounding-line retreat. This work directly addresses key goals of the West Antarctic Ice Sheet Initiative, which are to understand the dynamics, recent history and possible future behavior of the West Antarctic Ice Sheet.", "east": null, "geometry": null, "instruments": "EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS", "is_usap_dc": true, "keywords": "Surface Exposure Dates; FIELD SURVEYS; Aluminum-26; Erosion; Rock Samples; Beryllium-10; Exposure Age", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Stone, John", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Collaborative Research: Late Quaternary History of Reedy Glacier", "uid": "p0000029", "west": null}, {"awards": "0944475 Kaplan, Michael", "bounds_geometry": "POLYGON((-149.7 -84.1,-118.61 -84.1,-87.52 -84.1,-56.43 -84.1,-25.34 -84.1,5.75 -84.1,36.84 -84.1,67.93 -84.1,99.02 -84.1,130.11 -84.1,161.2 -84.1,161.2 -84.43,161.2 -84.76,161.2 -85.09,161.2 -85.42,161.2 -85.75,161.2 -86.08,161.2 -86.41,161.2 -86.74,161.2 -87.07,161.2 -87.4,130.11 -87.4,99.02 -87.4,67.93 -87.4,36.84 -87.4,5.75 -87.4,-25.34 -87.4,-56.43 -87.4,-87.52 -87.4,-118.61 -87.4,-149.7 -87.4,-149.7 -87.07,-149.7 -86.74,-149.7 -86.41,-149.7 -86.08,-149.7 -85.75,-149.7 -85.42,-149.7 -85.09,-149.7 -84.76,-149.7 -84.43,-149.7 -84.1))", "dataset_titles": "Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines", "datasets": [{"dataset_uid": "600115", "doi": "10.15784/600115", "keywords": "Antarctica; Cosmogenic Dating; Sample/collection Description; Sample/Collection Description; Solid Earth; Transantarctic Mountains", "people": "Kaplan, Michael", "repository": "USAP-DC", "science_program": null, "title": "Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines", "url": "https://www.usap-dc.org/view/dataset/600115"}], "date_created": "Thu, 17 Jul 2014 00:00:00 GMT", "description": "The proposed work will investigate changes in the compositional variation of glacial tills over time across two concentric sequences of Pleistocene moraines located adjacent to the heads of East Antarctic outlet glaciers in the Transantarctic Mountains (TAM). The chronologic framework for this work will be generated from cosmogenic exposure ages of boulders on prominent morainal ridges. The PIs hypothesize that variations in till composition may indicate a change in ice flow direction or a change in the composition of the original source area, while ages of the moraines provide a long-term terrestrial perspective on ice sheet dynamics. Both results are vital for modeling experiments that aim to reconstruct the East Antarctic Ice Sheet and assess its role in the global climate system and its potential impact on global sea level rise. The variation of till compositions through time also allows for a more accurate interpretation of sediment cores from the Ross Sea and the Southern Ocean. Additionally, till exposures at the head of some East Antarctic outlet glaciers have been shown to contain subglacial material derived from East Antarctic bedrock, providing a window through the ice to view East Antarctica?s inaccessible bedrock. Till samples will be collected from two well-preserved sequences of moraine crests at Mt. Howe (head of Scott Glacier) and Mt. Achernar (between Beardmore and Nimrod Glaciers). Each size fraction in glacial till provides potentially valuable information, and the PIs will measure the petrography of the clast and sand fractions, quantitative X-ray diffraction on the crushed \u003c2mm fraction, elemental abundance of the silt/clay fraction, and U/Pb of detrital zircons in the sand fraction. Data collection will rely on established methods previously used in this region and the PIs will also explore new methods to assess their efficacy. On the same moraines crests sampled for provenance studies, the PIs will sample for cosmogenic surface exposure analyses to provide a chronologic framework at the sites for provenance changes through time. \u003cbr/\u003e\u003cbr/\u003eBroader Impact \u003cbr/\u003eThe proposed research involves graduate and undergraduate training in a diverse array of laboratory methods. Students and PIs will be make presentations to community and campus groups, as well as conduct interviews with local news outlets. The proposed work also establishes a new, potentially long-term, collaboration between scientists at IUPUI and LDEO and brings a new PI (Kaplan) into the field of Antarctic Earth Sciences.", "east": 161.2, "geometry": "POINT(5.75 -85.75)", "instruments": null, "is_usap_dc": true, "keywords": "FIELD INVESTIGATION", "locations": null, "north": -84.1, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Kaplan, Michael", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -87.4, "title": "Collaborative Research: Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines", "uid": "p0000459", "west": -149.7}, {"awards": "0338224 Putkonen, Jaakko", "bounds_geometry": "POLYGON((161 -77,161.3 -77,161.6 -77,161.9 -77,162.2 -77,162.5 -77,162.8 -77,163.1 -77,163.4 -77,163.7 -77,164 -77,164 -77.1,164 -77.2,164 -77.3,164 -77.4,164 -77.5,164 -77.6,164 -77.7,164 -77.8,164 -77.9,164 -78,163.7 -78,163.4 -78,163.1 -78,162.8 -78,162.5 -78,162.2 -78,161.9 -78,161.6 -78,161.3 -78,161 -78,161 -77.9,161 -77.8,161 -77.7,161 -77.6,161 -77.5,161 -77.4,161 -77.3,161 -77.2,161 -77.1,161 -77))", "dataset_titles": "Cosmogenic nucilde data at ICE-D", "datasets": [{"dataset_uid": "200298", "doi": "", "keywords": null, "people": null, "repository": "ICE-D", "science_program": null, "title": "Cosmogenic nucilde data at ICE-D", "url": "https://version2.ice-d.org/antarctica/nsf/"}], "date_created": "Tue, 20 Nov 2007 00:00:00 GMT", "description": "This work will study cosmogenic isotope profiles of rock and sediment in the Dry Valleys of Antarctica to understand their origin. The results will provide important constraints on the history of the East Antarctic Ice Sheet. The near-perfect preservation of volcanic ash and overlying sediments suggests that hyperarid cold conditions have prevailed in the Dry Valleys for over 10 Myr. The survival of these sediments also suggests that warm-based ice has not entered the valley system and ice sheet expansion has been minimal. Other evidence, however, suggests that the Dry Valleys have experienced considerably more sediment erosion than generally believed: 1) the cosmogenic exposure ages of boulders and bedrock in the Valleys all show generally younger ages than volcanic ash deposits used to determine minimum ages of moraines and drifts, 2) there appears to be a discrepancy between the suggested extreme preservation of unconsolidated slope deposits (\u003e10 Myr) and adjacent bedrock that has eroded 2.6-6 m during the same time interval. The fact that the till and moraine exposure ages generally post date the overlying volcanic ash deposits could reflect expansion of continental ice sheet into the Dry Valleys with cold-based ice, thus both preserving the landscape and shielding the surfaces from cosmic radiation. Another plausible explanation of the young cosmogenic exposure ages is erosion of the sediments and gradual exhumation of formerly buried boulders to the surface. Cosmogenic isotope systematics are especially well suited to address these questions. We will measure multiple cosmogenic isotopes in profiles of rock and sediment to determine the minimum exposure ages, the degree of soil stability or mixing, and the shielding history of surfaces by cold based ice. We expect to obtain unambiguous minimum ages for deposits. In addition, we should be able to identify areas disturbed by periglacial activity, constrain the timing of such activity, and account for the patchy preservation of important stratigraphic markers such as volcanic ash. The broader impacts of this project include graduate and undergraduate education, and improving our understanding of the dynamics of Southern Hemisphere climate on timescales of millions of years, which has major implications for understanding the controls and impacts of global climate change.", "east": 164.0, "geometry": "POINT(162.5 -77.5)", "instruments": null, "is_usap_dc": true, "keywords": "ICE SHEETS; Dry Valleys; Not provided", "locations": "Dry Valleys", "north": -77.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Putkonen, Jaakko", "platforms": "Not provided", "repo": "ICE-D", "repositories": "ICE-D", "science_programs": null, "south": -78.0, "title": "Stability of Landscapes and Ice Sheets in Dry Valleys, Antarctica: A Systematic Study of Exposure Ages of Soils and Surface Deposits", "uid": "p0000575", "west": 161.0}]

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A Test of Global and Antarctic Models for Cosmogenic-nuclide Production Rates using High-precision Dating of 40Ar/39Ar Lava Flows from Mount Erebus

1644234

2022-12-12

Phillips, Fred; Kyle, Philip; Heizler, Matthew T

No dataset link provided

Nontechnical Description: The age of rocks and soils at the surface of the Earth can help answer multiple questions that are important for human welfare, including: when did volcanoes erupt and are they likely to erupt again? when did glaciers advance and what do they tell us about climate? what is the frequency of hazards such as landslides, floods, and debris flows? how long does it take soils to form and is erosion of soils going to make farming unsustainable? One method that is used thousands of times every year to address these questions is called 'cosmogenic surface-exposure dating'. This method takes advantage of cosmic rays, which are powerful protons and neutrons produced by supernova that constantly bombard the Earth's atmosphere. Some cosmic rays reach Earth's surface and produce nuclear reactions that result in rare isotopes. Measuring the quantity of the rare isotopes enables the length of time that the rock or soil has been exposed to the atmosphere to be calculated. The distribution of cosmic rays around the globe depends on Earth's magnetic field, and this distribution must be accurately known if useful exposure ages are to be obtained. Currently there are two remaining theories, narrowed down from many, of how to calculate this distribution. Measurements from a site that is at both high altitude and high latitude (close to the poles) are needed to test the two theories. This study involves both field and lab research and includes a Ph.D. student and an undergraduate student. The research team will collect rocks from lava flows on an active volcano in Antarctica named Mount Erebus and measure the amounts of two rare isotopes: 36Cl and 3He. The age of eruption of the samples will be determined using a highly accurate method that does not depend on cosmic rays, called 40Ar/39Ar dating. The two cosmic-ray theories will be used to calculate the ages of the samples using the 36Cl and 3He concentrations and will then be compared to the ages calculated from the 40Ar/39Ar dating. The accurate cosmic-ray theory will be the one that gives the same ages as the 40Ar/39Ar dating. Identification of the accurate theory will enable use of the cosmogenic surface dating methods anywhere on earth. Technical Description: Nuclides produced by cosmic rays in rocks at the surface of the earth are widely used for Quaternary geochronology and geomorphic studies and their use is increasing every year. The recently completed CRONUS-Earth Project (Cosmic-Ray Produced Nuclides on Earth) has systematically evaluated the production rates and theoretical underpinnings of cosmogenic nuclides. However, the CRONUS-Earth Project was not able to discriminate between the two leading theoretical approaches: the original Lal model (St) and the new Lifton-Sato-Dunai model (LSD). Mathematical models used to scale the production of the nuclides as a function of location on the earth, elevation, and magnetic field configuration are an essential component of this dating method. The inability to distinguish between the two models was because the predicted production rates did not differ sufficiently at the location of the calibration sites. The cosmogenic-nuclide production rates that are predicted by the two models differ significantly from each other at Erebus volcano, Antarctica. Mount Erebus is therefore an excellent site for testing which production model best describes actual cosmogenic-nuclide production variations over the globe. The research team recently measured 3He and 36Cl in mineral separates extracted from Erebus lava flows. The exposure ages for each nuclide were reproducible within each flow (~2% standard deviation) and in very good agreement between the 3He and the 36Cl ages. However, the ages calculated by the St and LSD scaling methods differ by ~15-25% due to the sensitivity of the production rate to the scaling at this latitude and elevation. These results lend confidence that Erebus qualifies as a suitable high- latitude/high-elevation calibration site. The remaining component that is still lacking is accurate and reliable independent (i.e., non-cosmogenic) ages, however, published 40Ar/39Ar ages are too imprecise and typically biased to older ages due to excess argon contained in melt inclusions. The research team's new 40Ar/39Ar data show that previous problems with Erebus anorthoclase geochronology are now overcome with modern mass spectrometry and better sample preparation. This indicates a high likelihood of success for this proposal in defining an accurate global scaling model. Although encouraging, much remains to be accomplished. This project will sample lava flows over 3 km in elevation and determine their 40Ar/39Ar and exposure ages. These combined data will discriminate between the two scaling methods, resulting in a preferred scaling model for global cosmogenic geochronology. The LSD method contains two sub-methods, the 'plain' LSD scales all nuclides the same, whereas LSDn scales each nuclide individually. The project can discriminate between these models using 3He and 36Cl data from lava flows at different elevations, because the first model predicts that the production ratio for these two nuclides will be invariant with elevation and the second that there should be ~10% difference over the range of elevations to be sampled. Finally, the project will provide a local, finite-age calibration site for cosmogenic-nuclide investigations in Antarctica.

Synoptic Evaluation of Long-Term Antarctic Ice Sheet Model Simulations using a Continent-Wide Database of Cosmogenic-Nuclide Measurements

1744771

2022-06-21

Balco, Gregory

5 million year transient Antarctic ice sheet model run with "sensitized" marine ice margin instabilities	USAP-DC
5 million year transient Antarctic ice sheet model run with "desensitized" marine ice margin instabilities	USAP-DC

The purpose of this project is to use geological data that record past changes in the Antarctic ice sheets to test computer models for ice sheet change. The geologic data mainly consist of dated glacial deposits that are preserved above the level of the present ice sheet, and range in age from thousands to millions of years old. These provide information about the size, thickness, and rate of change of the ice sheets during past times when the ice sheets were larger than present. In addition, some of these data are from below the present ice surface and therefore also provide some information about past warm periods when ice sheets were most likely smaller than present. The primary purpose of the computer model is to predict future ice sheet changes, but because significant changes in the size of ice sheets are slow and likely occur over hundreds of years or longer, the only way to determine whether these models are accurate is to test their ability to reproduce past ice sheet changes. The primary purpose of this project is to carry out such a test. The research team will compile relevant geologic data, in some cases generate new data by dating additional deposits, and develop methods and software to compare data to model simulations. In addition, this project will (i) contribute to building and sustaining U.S. science capacity through postdoctoral training in geochronology, ice sheet modeling, and data science, and (ii) improve public access to geologic data and model simulations relevant to ice sheet change through online database and website development. Technical aspects of this project are primarily focused on the field of cosmogenic-nuclide exposure-dating, which is a method that relies on the production of rare stable and radio-nuclides by cosmic-ray interactions with rocks and minerals exposed at the Earth's surface. Because the advance and retreat of ice sheets results in alternating cosmic-ray exposure and shielding of underlying bedrock and surficial deposits, this technique is commonly used to date and reconstruct past ice sheet changes. First, this project will contribute to compiling and systematizing a large amount of cosmogenic-nuclide exposure age data collected in Antarctica during the past three decades. Second, it will generate additional geochemical data needed to improve the extent and usefulness of measurements of stable cosmogenic nuclides, cosmogenic neon-21 in particular, that are useful for constraining ice-sheet behavior on million-year timescales. Third, it will develop a computational framework for comparison of the geologic data set with existing numerical model simulations of Antarctic ice sheet change during the past several million years, with particular emphasis on model simulations of past warm periods, for example the middle Pliocene ca. 3-3.3 million years ago, during which the Antarctic ice sheets are hypothesized to have been substantially smaller than present. Fourth, guided by the results of this comparison, it will generate new model simulations aimed at improving agreement between model simulations and geologic data, as well as diagnosing which processes or parameterizations in the models are or are not well constrained by the data. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Response of the Antarctic Ice Sheet to the last great global warming

1643248

2022-03-03

Hall, Brenda; Denton, George

Marshall Valley U-Series Data	USAP-DC
Walcott Glacier area radiocarbon data	USAP-DC
Pyramid Trough Radiocarbon Data	USAP-DC
Walcott Glacier Exposure Data	USAP-DC
Marshall Valley Radiocarbon Data	USAP-DC

Hall/1643248 This award supports a project to reconstruct the behavior of a portion of the East Antarctic Ice Sheet (the Ross Ice Sheet), using glacial geologic mapping and radiocarbon dating of algal deposits contained in glacial moraines, at the end of the last glacial period. The results will be compared with other dating methods that will be used on alpine glaciers that terminated in the mountains of the Royal Society Range in East Antarctica during the last glacial maximum and whose landforms intersect with those of the Ross Ice Sheet. Results from this comparison will contribute to a better understanding of the Antarctic ice sheet during the most recent global warming that ended the last ice age. This period is of interest since it will help inform our understanding of Antarctic ice sheet behavior in a future climate warming. Such data also will help inform models that attempt to simulate not only the behavior of the ice sheet during the end of the last ice age, but also its future response to elevated atmospheric carbon dioxide. The work will contribute to the education and training of both graduate and undergraduate students and results from the work will be incorporated in classes at the University of Maine. Results derived from the research will be disseminated to the public through lectures and visits to K-12 classrooms and data from this project will be downloadable from a University of Maine web site, as well as from public data repositories. The Antarctic Ice Sheet exerts a key control on global sea levels, both past and future, and strongly influences Southern Hemisphere and even global climate and ocean circulation. And yet a complete understanding of the evolution of the ice sheet over the last glacial cycle and of the mechanisms that caused it to advance and retreat is still lacking. Of particular interest is the response of the Antarctic Ice Sheet to the global warming that ended the last ice age, because it yields important clues about likely future ice-sheet behavior under a warming climate. In this project, scientists will reconstruct the thinning history of the Antarctic Ice Sheet in the Ross Sea sector during the last glacial/interglacial transition on the headlands of the southern Royal Society Range. They will use a combination of glacial geomorphological mapping and radiocarbon dating of algal deposits enclosed within recessional moraines. Finally, this record will be compared with a beryllium- and radiocarbon-dated chronology that will be produced of adjacent independent alpine glaciers that terminated on land during the last glacial maximum and whose deposits show cross-cutting relationships with those of the ice sheet. Results from this comparison will bear on the behavior of the Antarctic Ice Sheet during the termination of the last ice age. This work will support six students, including at least three undergraduates, and involves field work in the Antarctic.

OPP-PRF: High-resolution Nested Antarctic Ice Sheet Modeling to Reconcile Marine and Terrestrial Geologic Data

2138556

2021-11-09

Halberstadt, Anna Ruth

No dataset link provided

Geologic data provide crucial insights into Antarctic Ice Sheet dynamics; for example, progressive exposure of mountain peaks emerging from the ice sheet reveal ice elevation changes, and the past ‘footprint’ of marine-based ice sheets is imprinted on the seafloor. Numerical ice sheet simulations can link these geologic records in space and time to make larger-scale inferences about continent-wide ice sheet evolution. This work integrates both marine and terrestrial geologic datasets with numerical simulations to investigate Antarctic Ice Sheet behavior (and contribution to global sea level) throughout the last deglaciation, ~20,000 years ago until present. Specifically, this research addresses two issues regarding the relationship between simulations and data and their use in reconstructing past ice-sheet behavior: (1) Geologic records from the modern seafloor suggest significantly earlier retreat of marine-based ice compared to terrestrial records of mountain peak exposure (ice thinning). Computer experiments investigate several hypotheses for this mismatch in timing. (2) Exposure age data (terrestrial measurements recording ice elevation changes) are often interpreted to reflect ice dynamics hundreds of kilometers away from the study site. This work uses simulations to explore the linkage between ice elevation changes ‘upstream’ as glaciers flow through mountainous regions and ice dynamics further ‘downstream’ where ice contacts the ocean. This work will produce a publicly available, customizable, and easily accessible toolkit for comparing simulations and data, including a database of geologic records to use as constraints. The project is interdisciplinary, bridging a communication gap between the ice-sheet simulations and geologic data-collecting communities. This project combines numerical simulations and geologic data to explore fundamental knowledge gaps regarding the interpretation and use of marine and terrestrial datasets. This work will produce an ensemble of continent-wide coupled ice sheet and glacial isostatic adjustment simulations, constrained with comprehensive existing geologic data, to reproduce a history of deglacial Antarctic Ice Sheet evolution that is compatible with the geologic record as well as glaciologically and gravitationally self-consistent. Comparison between simulations and data is improved through high-resolution nested ice sheet modeling techniques, which provide unprecedented context for exposure age data generally located in regions of complex topography. Numerical simulations will be performed with systematically varied parameters and boundary conditions, and can thus support an investigation of (1) chronological mismatches between terrestrial thinning and marine ice sheet retreat during the mid-Holocene, and (2) how marine grounding-line dynamics are propagated upstream to coastal outlet glaciers and further interior under a variety of different scenarios. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Collaborative Research: Constraining West Antarctic Ice Sheet elevation during the last interglacial

1744949
1745015
1744927

2021-10-22

Braddock, Scott; Campbell, Seth; Ackert, Robert; Zimmerer, Matthew; Mitrovica, Jerry

Mt. Waesche ground-penetrating radar data 2018-2019

USAP-DC

This study will collect a novel dataset to determine how the West Antarctic Ice Sheet (WAIS) responded to a warmer climate during the last interglacial period (~125,000 years ago) by reconstructing the glacial history at the Mt. Waesche volcano. Reconstructing WAIS geometry when the ice sheet was smaller than present is difficult and data are lacking because the evidence lies beneath the present ice sheet. This study will drill through the ice sheet and recover bedrock that can be analyzed for its surface exposure history to help determine when the surface became overridden by the ice sheet. This study will provide constraints on the past maximum and minimum spatial extent of WAIS during the last glacial-interglacial cycle. Understanding the geometry of a reduced WAIS during intervals when the planet was warmer than present may provide a possible analogue for future environmental conditions given predicted temperature trends. A reduction of WAIS results in rising sea levels which threatens coastal communities across the globe. The data will help improve numerical ice sheet models to better predict WAIS response to current and future climate trends. The project supports a teacher educational workshop and the training of graduate and undergraduate students. The goal of this project is to obtain rock samples from beneath the WAIS through shallow (<80 m) drilling at Mt. Waesche, a volcano in Marie Byrd Land, near an ice dome of WAIS (2000 m elevation). The lithologies of lava flows exposed on the flank of the volcano are well-suited for cosmogenic 3He and 36Cl as well as 40Ar/39Ar measurements which will establish eruption and exposure age. Existing 40Ar/39Ar data indicate basaltic lava flows on the volcano flank as young as 350 ka. Thus, measured cosmogenic nuclides measured in rock cores from beneath the ice surface will be indicative of relatively recent exposure during periods of reduced ice elevation, most likely, during the last interglacial. The first field season is focused on identifying appropriate locations for drilling and a ground penetrating radar (GPR) survey of the subglacial topography <100m under the blue ice area. Mapping and dating the adjacent exposed lava flows will allow tracing of lava flows of known age and composition below the ice margin that will be targeted for drilling the following year. The second field season activities include drilling 8 boreholes (two transects) through blue ice with the Winkie drill near the ice margin to 80 m depth to obtain rock cores from the sub-ice lava flows. 3He exposure ages will constrain the duration and minimum extent of past surface lowering of the WAIS in Marie Byrd Land. Deeper GPR imaging (up to 700 m) will hope to reveal additional evidence of lava/ice interactions that would independently place constraints on lower ice levels during past eruptions. Results from this study will be compared with the modeled ice elevation histories at Mt. Waesche to validate ice sheet modeling efforts. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

COLLABORATIVE RESEARCH: Resolving Ambiguous Exposure-Age Chronologies of Antarctic Deglaciation with Measurements of In-Situ-Produced Cosmogenic Carbon-14

1542936
1542976

2021-09-03

Goehring, Brent; Balco, Gregory

Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom

ICE-D

The overall goal of this project is to determine the effect of past changes in the size of the Antarctic Ice Sheet on global sea level. At the peak of the last ice age 25,000 years ago, sea level was 120 meters (400 feet) lower than it is at present because water that is now part of the ocean was instead part of expanded glaciers and ice sheets in North America, Eurasia, and Antarctica. Between then and now, melting and retreat of this land ice caused sea level to rise. In this project, we aim to improve our understanding of how changes in the size of the Antarctic Ice Sheet contributed to this process. The overall strategy to accomplish this involves (i) visiting areas in Antarctica that are not now covered by ice; (ii) looking for geological evidence, specifically rock surface and sediment deposits, that indicates that these areas were covered by thicker ice in the past; and (iii) determining the age of these geological surfaces and deposits. This project addresses the final part of this strategy -- determining the age of Antarctic glacial rock surfaces or sediment deposits -- using a relatively new technique that involves measuring trace elements in rock surfaces that are produced by cosmic-ray bombardment after the rock surfaces are exposed by ice retreat. By applying this method to rock samples collected in previous visits to Antarctica, the timing of past expansion and contraction of the ice sheet can be determined. The main scientific outcomes expected from this project are (i) improved understanding of how Antarctic Ice Sheet changes contributed to past global sea level rise; and (ii) improved understanding of modern observed Antarctic Ice Sheet changes in a longer-term context. This second outcome will potentially improve predictions of future ice sheet behavior. Other outcomes of the project include training of individual undergraduate and graduate students, as well as the development of a new course on sea level change to be taught at Tulane University in New Orleans, a city that is being affected by sea level change today. This project will use measurements of in-situ-produced cosmogenic carbon-14 in quartz from existing samples collected at several sites in Antarctica to resolve major ambiguities in existing Last Glacial Maximum to present ice sheet reconstructions. This project is important because of the critical nature of accurate reconstructions of ice sheet change in constraining reconstructions of past sea level change. Although carbon-14 is most commonly exploited as a geochronometer through its production in the upper atmosphere and incorporation into organic materials, it is also produced within the crystal lattice of rocks and minerals that are exposed to the cosmic-ray flux at the Earth's surface. In this latter case, its concentration is proportional to the duration of surface exposure, and measurements of in-situ-produced carbon-14 can be used to date geological events that form or expose rock surfaces, for example, ice sheet expansion and retreat. Although carbon-14 is one of several trace radionuclides that can be used for this purpose, it is unique among them in that its half-life is short relative to the time scale of glacial-interglacial variations. Thus, in cases where rock surfaces in polar regions have been repeatedly covered and uncovered by ice sheet change during many glacial-interglacial cycles, carbon-14 measurements are uniquely suited to accurately dating the most recent episode of ice sheet advance and retreat. We aim to use this property to improve our understanding of Antarctic Ice Sheet change at a number of critically located sites at which other surface exposure dating methods have yielded ambiguous results. Geographically, these are focused in the Weddell Sea embayment of Antarctica, which is an area where the geometry of the Antarctic continent potentially permits large glacial-interglacial changes in ice volume but where existing geologic records of ice sheet change are particularly ambiguous. In addition, in-situ carbon-14 measurements, applied where independently constrained deglaciation chronologies already exist, can potentially allow us to date the last period of ice sheet advance as well as the most recent retreat.

Integrating petrologic records and geodynamics: Quantifying the effects of glaciation on crustal stress and eruptive patterns at Mt. Waesche, Executive Committee Range, Antarctica

2122248

2021-08-19

Waters, Laura; Naliboff, John; Zimmerer, Matthew

No dataset link provided

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The geologic record reveals that volcanic activity increases when glaciers retreat and major ice sheets thin. This relationship produces a positive feedback mechanism where the uptick in volcanism increases greenhouse gasses concentrations, leading to climate warming and further deglaciation. Although the pattern between volcanism and deglaciation is observed in the geologic record, the exact mechanism(s) by which glaciers impact a volcanic plumbing system is unknown. This project focuses on Mount Waesche, a volcano in West Antarctica, that frequently erupts during warm, interglacial periods and undergoes a period of less activity during cold, glacial periods. This project will examine compositions of the rocks and minerals from Mount Waesche to determine magma storage depths, allowing the investigators to understand how magma plumbing systems change in response to glacial cycles. These results will be compared with geodynamic simulations to understand the physics behind the effects of deglaciation on the magmatic plumbing systems within Earth’s crust. The investigators will additionally partner with Mentoring Kids Works to develop several Polar and Earth Science Educational Modules aimed at improving reading skills in third grade students in New Mexico. The proposed Polar and Earth Science program consists of modules that include readings of books introducing students to Earth and Polar science themes, paired with Earth and Polar Science activities, followed by simple experiments, where students make predictions and collect data. Information required to implement our Polar and Earth Science curriculum will be made available online. Isotopic and sedimentary datasets reveal that volcanic activity typically increases during interglacial periods. However, the physical mechanisms through which changes in the surface loading affect volcanic magmatic plumbing systems remain unconstrained. Recently generated 40Ar/39Ar eruption ages indicate that 86% of the dated samples from Mt. Waesche, a late Quaternary volcano in Marie Byrd land, correlate with interglacial periods, suggesting this volcano uniquely responds to changes in the West Antarctic Ice Sheet. We propose to combine the petrology of Mount Waesche’s volcanic record, constraints on changing ice loads through time, and geodynamic modelling to: (1) Determine how pre-eruptive storage conditions change during glacial and interglacial periods using whole rock and mineral compositions of volcanic rocks; (2) Conduct geodynamic modeling to elucidate the relationship between lithospheric structure, temporal variations in ice sheet thickness, and subsequent changes in crustal stresses and magmatic transport and, therefore, the mechanism(s) by which deglaciation impacts magmatic plumbing systems; (3) Use the outcomes of objectives (1) and (2) to provide new constraints on the changes in ice sheet thickness through time that could plausibly trigger future volcanic and magmatic activity in West Antarctica. This collaborative approach will provide a novel methodology to determine prior magnitudes and rates of ice load changes within the Marie Byrd Land region of Antarctica. Lastly, estimates of WAIS elevation changes from this study will be compared to ongoing studies at Mount Waesche focused on constraining last interglacial ice sheet draw down using cosmogenic exposure ages obtained from shallow drilling. The scope of work also includes a partnership with Mentoring Kids Works to develop several Polar and Earth Science Educational Modules aimed at improving reading skills in third grade students in New Mexico. The proposed Polar and Earth Science program consists of modules that include readings of books introducing students to Earth and Polar science themes, paired with Earth and Polar Science activities, followed by simple experiments, where students make predictions and collect data. Information required to implement our Polar and Earth Science curriculum will be made available online. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Collaborative Research: Potential Direct Geologic Constraint of Ice Sheet Thickness in the Central Transantarctic Mountains during the Pliocene Warm Period

1443329
1443321

2020-12-20

Balco, Gregory; Bromley, Gorden; BROMLEY, GORDON

Interface for viewing observational data related to exposure ages measurements and calculated geologic ages derived therefrom

ICE-D

This investigation will reconstruct past behavior of the East Antarctic Ice Sheet during periods of warmer-than-present climate, such as the Pliocene, in order to better project the likely response of Earth's largest ice sheet to anthropogenic warming. Containing the equivalent of ~55 m sea-level rise, the future evolution of the East Antarctic Ice Sheet has clear societal ramifications on a global scale as temperatures continue to rise. Therefore, determining ice-sheet sensitivity to climate on the scale predicted for the next two centuries is a matter of increasing urgency, particularly in light of evidence suggesting the East Antarctic Ice Sheet is more dynamic than previously thought. This research will provide a terrestrial geologic record of long-term ice-sheet behavior from sites immediately adjacent the East Antarctic Ice Sheet in the Transantarctic Mountains, with which the project will help ascertain how the ice sheet responded to past warm periods. The project will focus primarily on the Pliocene warm period, 5 to 3 million years ago, as this represents the closest analogue to 21st Century climate conditions. The proposed research will investigate glacial deposits corresponding to the East Antarctic Ice Sheet in the central Transantarctic Mountains in order to expand the geologic record of past ice-sheet behavior. The overarching research objectives are to improve understanding of the East Antarctic Ice Sheet's configuration during periods of warmer-than-present climate, such as the Pliocene warm period, and to determine whether the ice sheet underwent significant volume changes or remained relatively stable in response to warming. To address these goals, the investigation will map and date glacial deposits preserved at mountain sites immediately adjacent the ice sheet. Specifically, we will: (i) employ multiple cosmogenic nuclides (10Be, 26Al, 21Ne) to establish more fully ice-thickness histories for the upper Shackleton and Beardmore Glaciers, where they exit the ice sheet; (ii) use this record to identify periods during which the East Antarctic Ice Sheet was at least as extensive as today; and (iii) use these data to assess long-term ice-sheet variability in East Antarctica, with particular emphasis on Pliocene warm episodes. This research will require Antarctic fieldwork, glacial-geologic mapping, and cosmogenic surface-exposure dating.

Collaborative Research: Last Glacial Maximum and Deglaciation Chronology for the Foundation Ice Stream and Southeastern Weddell Sea Embayment

0838256
0838784
0838783

2020-12-19

Balco, Gregory; Todd, Claire; Conway, Howard

Web page linking to documents containing data collected in this project. Static content	PI website
Interface to observational data collected in this project and geologic age information derived therefrom. Dynamic content, continuously updated.	ICE-D

This award supports a project to find and date geologic evidence of past ice-marginal positions in the Pensacola Mountains, which border the Foundation Ice Stream at the head of the Weddell Sea embayment. The project will involve glacial geologic mapping and cosmogenic-nuclide surface exposure dating of glacially transported erratics. An ice-flow model will be used to link our exposure-dating results together in a glaciologically consistent way, and to relate them to regional LGM to Holocene elevation changes. A secondary focus of the project seeks to improve the effectiveness of exposure-dating methods in understanding ice sheet change. Changes in the location of the ice margin, and thus the exposure ages that record these changes, are controlled not only by regional ice sheet mass balance, but also by local effects on snow- and icefields immediately adjacent to the exposure-dating sites. This part of the project will combine glaciological observations near the present ice margin with targeted exposure- age sampling in an effort to better understand the processes controlling the ice margin location, and improve the interpretation of very recent exposure-age data as a record of latest Holocene to present ice sheet changes. The intellectual merit of the project is that it will provide direct geologic evidence of LGM-to-Holocene ice volume change in a region of Antarctica where no such evidence now exists. The broader impacts of the work involve both gathering information needed for accurate understanding of past and present global sea level change. Secondly, this project will help to develop and maintain the human and intellectual resources necessary for continued excellence in polar research and global change education, by linking experienced Antarctic researchers with early career scientists who seek to develop their expertise in both research and education. In addition, it brings together two early career scientists whose careers are focused at opposite ends of the research-education spectrum, thus facilitating better integration of research and education both in the careers of these scientists and in the outcome of this project. This award has field work in Antarctica.

Collaborative Research: Multidisciplinary Analysis of Antarctic Blue Ice Moraine Formation and their Potential as Climate Archives over Multiple Glacial Cycles

1443433
1443213

2020-09-29

Kaplan, Michael; Schaefer, Joerg; Winckler, Gisela; Licht, Kathy

3He input data	USAP-DC
10Be and 26Al cosmogenic nuclide surface exposure data	USAP-DC

Licht/1443433 Sediments deposited by the Antarctic ice sheet are an archive of its history with time and help geologists to determine how the remote interior of the ice sheet has changed over the past several hundred thousand years. This project will focus on the formation and dynamics of moraines (accumulations of dirt and rocks that are incorporated in the glacier surface or have been pushed along by the glacier as it moves) near the blue ice area of Mt. Achernar in the central Transantarctic Mountains in Antarctica.. The study will improve basic understanding of the formation of these moraines. Fieldwork at the site will focus on imaging the internal structure of the moraine to determine the processes by which it, and others like it, form over time. Additional analyses will include measurements of ice flow and collection of rock samples to determine the timing of debris deposition and the changes in the sources of sediments from deep within the Antarctic continent. The project will provide both graduate and undergraduate students training in paleoclimate studies, geology, and numerical modeling approaches. The broader impacts of the proposed work include hands on training in the Earth Sciences for graduate and undergraduate students, collaboration with colleagues in New Zealand and Sweden to provide an international research experience for students from the US, and three educational modules to be delivered by student researchers regarding Antarctica's role in global environments. The research is societally relevant and multidisciplinary and the topics are ideal for sharing with the public. All research findings will be made publicly available to others via timely publication in high-impact, peer-reviewed journals and all data will be submitted to the National Snow and Ice Data Center, and excess samples will be provided to the U.S. Polar Rock Repository. Direct observations of ice sheet history from the margins of Antarctica's polar plateau are essential for testing numerical ice sheet models, and the laterally extensive, blue-ice moraines of the Mt. Achernar Moraine complex in the central Transantarctic Mountains contain a unique and nearly untapped direct, quasi-continuous record of ice sheet change over multiple glacial cycles. The project objectives include improved understanding of processes and rates of blue ice moraine formation, as well as identifying the topographic, glaciological, and climatic controls on their evolution. Data to be collected with fieldwork in Antarctica include: imaging of internal ice structure with ground-penetrating radar, measurement of ice flow velocity and direction with a global positioning system (GPS) array, analysis of debris concentration and composition in glacier ice, state-of-the-art cosmogenic multi-nuclide analyses to determine exposure ages of moraine debris, mapping of trimlines and provenance analysis. Numerical model simulations, constrained by field data, will be used to evaluate the factors influencing changes in glacier flow that potentially impact the accumulation of the moraine debris. All together, the new data and modeling efforts will improve conceptual models of blue ice moraine formation, and thereby make them a more valuable proxy for developing a better understanding of the history of the ice sheet.

Air-Ground Study of Tectonics at the Boundary Between the Eastern Ross Embayment and Western Marie Byrd Land, Antarctica: Basement Geology and Structure

9615282
9615281

2020-04-24

Luyendyk, Bruce P.; Siddoway, Christine

SOAR-WMB Airborne gravity data	USAP-DC
Bedrock sample data, Ford Ranges region (Marie Byrd Land)	USAP-DC

OPP 9615281 Luyendyk OPP 9615282 Siddoway Abstract This award supports a collaborative project that combines air and ground geological-geophysical investigations to understand the tectonic and geological development of the boundary between the Ross Sea Rift and the Marie Byrd Land (MBL) volcanic province. The project will determine the Cenozoic tectonic history of the region and whether Neogene structures that localized outlet glacier flow developed within the context of Cenozoic rifting on the eastern Ross Embayment margin, or within the volcanic province in MBL. The geological structure at the boundary between the Ross Embayment and western MBL may be a result of: 1) Cenozoic extension on the eastern shoulder of the Ross Sea rift; 2) uplift and crustal extension related to Neogene mantle plume activity in western MBL; or a combination of the two. Faulting and volcanism, mountain uplift, and glacier downcutting appear to now be active in western MBL, where generally East-to-West-flowing outlet glaciers incise Paleozoic and Mesozoic bedrock, and deglaciated summits indicate a previous North-South glacial flow direction. This study requires data collection using SOAR (Support Office for Aerogeophysical Research, a facility supported by Office of Polar Programs which utilizes high precision differential GPS to support a laser altimeter, ice-penetrating radar, a towed proton magnetometer, and a Bell BGM-3 gravimeter). This survey requires data for 37,000 square kilometers using 5.3 kilometer line spacing with 15.6 kilometer tie lines, and 86,000 square kilometers using a grid of 10.6 by 10.6 kilometer spacing. Data will be acquired over several key features in the region including, among other, the eastern edge of the Ross Sea rift, over ice stream OEO, the transition from the Edward VII Peninsula plateau to the Ford Ranges, the continuation to the east of a gravity high known from previous reconnaissance mapping over the Fosdick Metamorphic Complex, an d the extent of the high-amplitude magnetic anomalies (volcanic centers?) detected southeast of the northern Ford Ranges by other investigators. SOAR products will include glaciology data useful for studying driving stresses, glacial flow and mass balance in the West Antarctic Ice Sheet (WAIS). The ground program is centered on the southern Ford Ranges. Geologic field mapping will focus on small scale brittle structures for regional kinematic interpretation, on glaciated surfaces and deposits, and on datable volcanic rocks for geochronologic control. The relative significance of fault and joint sets, the timing relationships between them, and the probable context of their formation will also be determined. Exposure ages will be determined for erosion surfaces and moraines. Interpretation of potential field data will be aided by on ground sampling for magnetic properties and density as well as ground based gravity measurements. Oriented samples will be taken for paleomagnetic studies. Combined airborne and ground investigations will obtain basic data for describing the geology and structure at the eastern boundary of the Ross Embayment both in outcrop and ice covered areas, and may be used to distinguish between Ross Sea rift- related structural activity from uplift and faulting on the perimeter of the MBL dome and volcanic province. Outcrop geology and structure will be extrapolated with the aerogeophysical data to infer the geology that resides beneath the WAIS. The new knowledge of Neogene tectonics in western MBL will contribute to a comprehensive model for the Cenozoic Ross rift and to understanding of the extent of plume activity in MBL. Both are important for determining the influence of Neogene tectonics on the ice streams and WAIS.

Collaborative Research: High-resolution Reconstruction of Holocene Deglaciation in the Southern Ross Embayment

1443248
1443346

2019-09-05

Hall, Brenda; Stone, John

Ice-D Antarctic Cosmogenic Nuclide database - site DUNCAN	ICE-D
Liv and Amundsen Glacier Radiocarbon Data	USAP-DC
Cosmogenic nuclide data from glacial deposits along the Liv Glacier coast	USAP-DC
Ice-D Antarctic Cosmogenic Nuclide database - site MAASON	ICE-D

The response of the Antarctic Ice Sheet to future climatic changes is recognized as the greatest uncertainty in projections of future sea level. An understanding of past ice fluctuations affords insight into ice-sheet response to climate and sea-level change and thus is critical for improving sea-level predictions. This project will examine deglaciation of the southern Ross Sea over the past few thousand years to document oscillations in Antarctic ice volume during a period of relatively stable climate and sea level. We will help quantify changes in ice volume, improve understanding of the ice dynamics responsible, and examine the implications for future sea-level change. The project will train future scientists through participation of graduate students, as well as undergraduates who will develop research projects in our laboratories. Previous research indicates rapid Ross Sea deglaciation as far south as Beardmore Glacier early in the Holocene epoch (which began approximately 11,700 years before present), followed by more gradual recession. However, deglaciation in the later half of the Holocene remains poorly constrained, with no chronological control on grounding-line migration between Beardmore and Scott Glaciers. Thus, we do not know if mid-Holocene recession drove the grounding line rapidly back to its present position at Scott Glacier, or if the ice sheet withdrew gradually in the absence of significant climate forcing or eustatic sea level change. The latter possibility raises concerns for future stability of the Ross Sea grounding line. To address this question, we will map and date glacial deposits on coastal mountains that constrain the thinning history of Liv and Amundsen Glaciers. By extending our chronology down to the level of floating ice at the mouths of these glaciers, we will date their thinning history from glacial maximum to present, as well as migration of the Ross Sea grounding line southwards along the Transantarctic Mountains. High-resolution dating will come from Beryllium-10 surface-exposure ages of erratics collected along elevation transects, as well as Carbon-14 dates of algae within shorelines from former ice-dammed ponds. Sites have been chosen specifically to allow close comparison of these two dating methods, which will afford constraints on Antarctic Beryllium-10 production rates.

Collaborative Research: Assessing the Antarctic Contribution to Sea-level Changes during the Last Deglaciation: Constraints from Darwin Glacier

1246110
1246170

2017-10-23

Hall, Brenda; Stone, John; Conway, Howard

Darwin and Hatherton Glaciers	ICE-D
Hatherton Glacier Radiocarbon Data	USAP-DC

Collaborative Research: Terrestrial Exposure-Age Constraints on the last Glacial Maximum Extent of the Antarctic Ice Sheet in the Western Ross Sea

1460449
1341420
1341364

2017-10-18

Goehring, Brent; Balco, Gregory; Todd, Claire

Interface to observational data associated with exposure-age measurements and resulting calculated ages. Dynamic content, updated.

ICE-D

Collaborative Research: Multi-nuclide approach to systematically evaluate the scatter in surface exposure ages in Antarctica and to develop consistent alpine glacier chronologies

1043724

2015-12-05

Swanger, Kate

No dataset link provided

Intellectual Merit: The PIs propose to investigate the impact of earth surface processes on the application of cosmogenic exposure dating in Antarctica by combining multi-nuclide techniques, detailed field experiments, rock-mechanic studies, and climate modeling. They will analyze cosmogenic-nuclide inventories for a suite of six alpine-moraine systems in inland regions of the McMurdo Dry Valleys. This area is ideally suited for this study because 1) the targeted alpine moraine sequences are critically important in helping to reconstruct past temperature and precipitation values over the last several million years, 2) the production rates for cosmogenic nuclides are typically high and well-known, and 3) the complexity of surface processes is relatively low. Their work has two specific goals: to evaluate the effects of episodic geomorphic events in modulating cosmogenic inventories in surface rocks in polar deserts and to generate an alpine glacier chronology that will serve as a robust record of regional climate variation over the last several million years. A key objective is to produce a unique sampling strategy that yields consistent exposure-age results by minimizing the effects of episodic geomorphic events that obfuscate cosmogenic-nuclide chronologies. They will link their moraine chronology with regional-scale atmospheric models developed by collaborators at University of Massachusetts Amherst. Broader impacts: This research is interdisciplinary and includes two early career scientists. Results of this work will be used to enhance undergraduate education by engaging two female students in Antarctic field and summer research projects. Extended outreach includes development of virtual Antarctic field trips for Colgate University?s Ho Tung Visualization Laboratory and Boston University?s Antarctic Digital Image Analyses Laboratory. The PIs will continue to work with the Los Angeles Valley Community College, which serves students of mostly Hispanic origin as part of the PolarTREC program. This project will contribute to the collaboration between LDEO and several New York City public high schools within the Lamont-Doherty Secondary School Field Program.

Collaborative Research: Multi-nuclide approach to systematically evaluate the scatter in surface exposure ages in Antarctica and to develop consistent alpine glacier chronologies

1043706

2015-10-23

Marchant, David

No dataset link provided

Collaborative Research: Late Quaternary History of Reedy Glacier

0229314

2015-03-30

Stone, John

Reedy Glacier Exposure Ages, Antarctica

USAP-DC

The stability of the marine West Antarctic Ice Sheet (WAIS) remains an important, unresolved problem for predicting future sea level change. Recent studies indicate that the mass balance of the ice sheet today may be negative or positive. The apparent differences may stem in part from short-term fluctuations in flow. By comparison, geologic observations provide evidence of behavior over much longer time scales. Recent work involving glacial-geologic mapping, dating and ice-penetrating radar surveys suggests that deglaciation of both the Ross Sea Embayment and coastal Marie Byrd Land continued into the late Holocene, and leaves open the possibility of ongoing deglaciation and grounding-line retreat. However, previous work in the Ross Sea Embayment was based on data from just three locations that are all far to the north of the present grounding line. Additional data from farther south in the Ross Sea Embayment are needed to investigate whether recession has ended, or if the rate and pattern of deglaciation inferred from our previous study still apply to the present grounding line. This award provides support to reconstruct the evolution of Reedy Glacier, in the southern Transantarctic Mountains, since the Last Glacial Maximum (LGM). Because Reedy Glacier emerges from the mountains above the grounding line, its surface slope and elevation should record changes in thickness of grounded ice in the Ross Sea up to the present day. The deglaciation chronology of Reedy Glacier therefore can indicate whether Holocene retreat of the WAIS ended thousands of years ago, or is still continuing at present. This integrated glaciologic, glacial-geologic, and cosmogenic-isotope exposure- dating project will reconstruct past levels of Reedy Glacier. Over two field seasons, moraines will be mapped, dated and correlated at sites along the length of the glacier. Radar and GPS measurements will be made to supplement existing ice thickness and velocity data, which are needed as input for a model of glacier dynamics. The model will be used to relate geologic measurements to the grounding-line position downstream. Ultimately, the mapping, dating and ice-modeling components of the study will be integrated into a reconstruction that defines changes in ice thickness in the southern Ross Sea since the LGM, and relates these changes to the history of grounding-line retreat. This work directly addresses key goals of the West Antarctic Ice Sheet Initiative, which are to understand the dynamics, recent history and possible future behavior of the West Antarctic Ice Sheet.

Collaborative Research: Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines

0944475

2014-07-17

Kaplan, Michael

Pleistocene East Antarctic Ice Sheet History as Recorded in Sediment Provenance and Chronology of High-elevation TAM Moraines

USAP-DC

The proposed work will investigate changes in the compositional variation of glacial tills over time across two concentric sequences of Pleistocene moraines located adjacent to the heads of East Antarctic outlet glaciers in the Transantarctic Mountains (TAM). The chronologic framework for this work will be generated from cosmogenic exposure ages of boulders on prominent morainal ridges. The PIs hypothesize that variations in till composition may indicate a change in ice flow direction or a change in the composition of the original source area, while ages of the moraines provide a long-term terrestrial perspective on ice sheet dynamics. Both results are vital for modeling experiments that aim to reconstruct the East Antarctic Ice Sheet and assess its role in the global climate system and its potential impact on global sea level rise. The variation of till compositions through time also allows for a more accurate interpretation of sediment cores from the Ross Sea and the Southern Ocean. Additionally, till exposures at the head of some East Antarctic outlet glaciers have been shown to contain subglacial material derived from East Antarctic bedrock, providing a window through the ice to view East Antarctica?s inaccessible bedrock. Till samples will be collected from two well-preserved sequences of moraine crests at Mt. Howe (head of Scott Glacier) and Mt. Achernar (between Beardmore and Nimrod Glaciers). Each size fraction in glacial till provides potentially valuable information, and the PIs will measure the petrography of the clast and sand fractions, quantitative X-ray diffraction on the crushed <2mm fraction, elemental abundance of the silt/clay fraction, and U/Pb of detrital zircons in the sand fraction. Data collection will rely on established methods previously used in this region and the PIs will also explore new methods to assess their efficacy. On the same moraines crests sampled for provenance studies, the PIs will sample for cosmogenic surface exposure analyses to provide a chronologic framework at the sites for provenance changes through time. <br/><br/>Broader Impact <br/>The proposed research involves graduate and undergraduate training in a diverse array of laboratory methods. Students and PIs will be make presentations to community and campus groups, as well as conduct interviews with local news outlets. The proposed work also establishes a new, potentially long-term, collaboration between scientists at IUPUI and LDEO and brings a new PI (Kaplan) into the field of Antarctic Earth Sciences.

Stability of Landscapes and Ice Sheets in Dry Valleys, Antarctica: A Systematic Study of Exposure Ages of Soils and Surface Deposits

0338224

2007-11-20

Putkonen, Jaakko

Cosmogenic nucilde data at ICE-D

ICE-D

This work will study cosmogenic isotope profiles of rock and sediment in the Dry Valleys of Antarctica to understand their origin. The results will provide important constraints on the history of the East Antarctic Ice Sheet. The near-perfect preservation of volcanic ash and overlying sediments suggests that hyperarid cold conditions have prevailed in the Dry Valleys for over 10 Myr. The survival of these sediments also suggests that warm-based ice has not entered the valley system and ice sheet expansion has been minimal. Other evidence, however, suggests that the Dry Valleys have experienced considerably more sediment erosion than generally believed: 1) the cosmogenic exposure ages of boulders and bedrock in the Valleys all show generally younger ages than volcanic ash deposits used to determine minimum ages of moraines and drifts, 2) there appears to be a discrepancy between the suggested extreme preservation of unconsolidated slope deposits (>10 Myr) and adjacent bedrock that has eroded 2.6-6 m during the same time interval. The fact that the till and moraine exposure ages generally post date the overlying volcanic ash deposits could reflect expansion of continental ice sheet into the Dry Valleys with cold-based ice, thus both preserving the landscape and shielding the surfaces from cosmic radiation. Another plausible explanation of the young cosmogenic exposure ages is erosion of the sediments and gradual exhumation of formerly buried boulders to the surface. Cosmogenic isotope systematics are especially well suited to address these questions. We will measure multiple cosmogenic isotopes in profiles of rock and sediment to determine the minimum exposure ages, the degree of soil stability or mixing, and the shielding history of surfaces by cold based ice. We expect to obtain unambiguous minimum ages for deposits. In addition, we should be able to identify areas disturbed by periglacial activity, constrain the timing of such activity, and account for the patchy preservation of important stratigraphic markers such as volcanic ash. The broader impacts of this project include graduate and undergraduate education, and improving our understanding of the dynamics of Southern Hemisphere climate on timescales of millions of years, which has major implications for understanding the controls and impacts of global climate change.

USAP-DC

U.S. ANTARCTIC PROGRAM DATA CENTER

The Results Map and the Results Table

Defining a search area on the Results Map

Viewing map layers on the Results Map

Search USAP Projects And Datasets

Older retrieved projects from AMD. Warning: many have incomplete information.

To sort the table of search results, click the header of the column you wish to search by. To sort by multiple columns, hold down the shift key whilst selecting the sort columns in order.