USAP-DC

{"dp_type": "Dataset", "free_text": "Deformation"}

[{"awards": "1851022 Fudge, Tyler", "bounds_geometry": null, "date_created": "Fri, 22 Nov 2024 00:00:00 GMT", "description": "", "east": null, "geometry": null, "keywords": "Antarctica; Cryosphere", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Fudge, T. J.", "project_titles": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation", "projects": [{"proj_uid": "p0010211", "repository": "USAP-DC", "title": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Forward Diffusion Model used to calculate widening of volcanic layer widths", "uid": "601857", "west": null}, {"awards": "1851022 Fudge, Tyler", "bounds_geometry": null, "date_created": "Fri, 22 Nov 2024 00:00:00 GMT", "description": "This data set is code and necessary files for calculating the mean scaled gradient as described in Fudge et al., 2024. The code is in Matlab and will reproduce Figure 4.", "east": null, "geometry": null, "keywords": "Antarctica; Cryosphere", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Fudge, T. J.", "project_titles": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation", "projects": [{"proj_uid": "p0010211", "repository": "USAP-DC", "title": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Code for calculating mean gradient for EDC sulfate data", "uid": "601856", "west": null}, {"awards": "1851022 Fudge, Tyler", "bounds_geometry": ["POINT(123.35 -75.1)"], "date_created": "Fri, 22 Nov 2024 00:00:00 GMT", "description": "This data sets contains the width of volcanic events as identified in the Dome C ice core and described in Fudge et al., 2024", "east": 123.35, "geometry": ["POINT(123.35 -75.1)"], "keywords": "Antarctica; Cryosphere", "locations": "Antarctica", "north": -75.1, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Fudge, T. J.", "project_titles": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation", "projects": [{"proj_uid": "p0010211", "repository": "USAP-DC", "title": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -75.1, "title": "Volcanic Widths in Dome C Interglacials and Glacials", "uid": "601855", "west": 123.35}, {"awards": "1643120 Iverson, Neal", "bounds_geometry": null, "date_created": "Mon, 16 Sep 2024 00:00:00 GMT", "description": "Accurately modeling the deformation of temperate glacier ice, which is at its pressure-melting temperature and contains liquid water at grain boundaries, is essential for predicting ice sheet discharge to the ocean and associated sea-level rise. Central to such modeling is Glen\u2019s flow law, in which strain rate depends on stress raised to a power of n=3-4. In sharp contrast to this nonlinearity, we find by conducting large-scale, shear-deformation experiments to tertiary creep that temperate ice is linear-viscous (n\u22481.0) over common ranges of liquid water content and stress expected near glacier beds and in ice stream margins. This linearity is likely caused by diffusive pressure-melting and refreezing at grain boundaries and could help stabilize modeled responses of ice sheets to shrinkage-induced stress increases.", "east": null, "geometry": null, "keywords": "Antarctica; Cryosphere", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Iverson, Neal", "project_titles": "NSFGEO-NERC: Collaborative Research: Two-Phase Dynamics of Temperate Ice", "projects": [{"proj_uid": "p0010197", "repository": "USAP-DC", "title": "NSFGEO-NERC: Collaborative Research: Two-Phase Dynamics of Temperate Ice"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Tertiary creep rates of temperate ice containing greater than 0.7% liquid water", "uid": "601833", "west": null}, {"awards": null, "bounds_geometry": null, "date_created": "Thu, 05 Sep 2024 00:00:00 GMT", "description": "The effects of soluble impurities on the flow of glaciers and ice sheets as well as the effects of ice flow on impurities migration are not well understood. This study investigates the effects of sulfuric acid (H2SO4) concentrations ranging from 10 to 25 ppm on the flow and fabric of polycrystalline ice under compression at temperatures of -3\u00b0C and -12\u00b0C. The results show that H2SO4-doped polycrystalline ice deforms significantly faster than high-purity polycrystalline ice, with the deformation rate being 1.5 to 3 times higher. At -12\u00b0C, the presence of H2SO4 within the grains induces the most ice softening, whereas at -3\u00b0C, H2SO4\u0027s softening effects are observed both within the grains and at grain boundaries. The migration of H2SO4 to grain boundaries during deformation leads to the formation of a liquid-like layer, with increased solubility at higher temperatures potentially homogenizing the impurities within the ice matrix. This homogenization at -3\u00b0C suggests that post-depositional processes near the bed of ice sheets could significantly alter sulfate records. At -12\u00b0C, where homogenization is absent, impurity-induced dislocation processes may heavily influence deformation and impurity migration. Additionally, the comparison of natural ice with lab-grown samples indicates that fabric development significantly impacts compressive strength and creep rates, with implications for the understanding of impurity-induced deformation processes in polar ice.", "east": null, "geometry": null, "keywords": "Antarctica; Cryosphere", "locations": "Antarctica", "north": null, "nsf_funding_programs": null, "persons": "Ogunmolasuyi, Ayobami", "project_titles": null, "projects": null, "repositories": null, "science_programs": null, "south": null, "title": "The Impacts of the Microstructural Location of H2SO4 on the Flow of Polycrystalline Ice", "uid": "601831", "west": null}, {"awards": "2023355 Schmandt, Brandon", "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))"], "date_created": "Wed, 26 Jun 2024 00:00:00 GMT", "description": "This catalog/dataset contains 60,006 seismic events between magnitude (Mw) -1.0 and 4.5. It was obtained using publicly available seismic data from 2000 through 2020. The catalog was generated using a workflow that includes new and established software for earthquake detection (Mousavi et al., 2020; Woollam et al., 2022), association (Zhang et al., 2019), location (Lomax et al., 2000, 2009) and magnitude estimation (Satriano, 2022). Events in the catalog are located near volcanoes, outlet glaciers, ice shelves, and within the continental interior. The catalog thus includes events from diverse source processes (cryospheric, volcanic, and tectonic). Preliminary observations include thousands of events near Mount Erebus, Ross Island, and the McMurdo Sound region, repeated seismic events at Ice Streams or large glaciers, and deep long period events in Marie Byrd Land Executive Committee Range. The file contains the latitude, longitude, depth, origin time, Magnitude, errors in the locations and the RMS. More details of the data set and all relevant methods can be found in Pena Castro et al., 2024.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Cryosphere; Earthquakes; Icequakes; Volcanic Events", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Pena Castro, Andres", "project_titles": "EAGER: Lowering the detection threshold of Antarctic seismicity to reveal undiscovered intraplate deformation", "projects": [{"proj_uid": "p0010450", "repository": "USAP-DC", "title": "EAGER: Lowering the detection threshold of Antarctic seismicity to reveal undiscovered intraplate deformation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "A seismic catalog for the southernmost continent", "uid": "601805", "west": -180.0}, {"awards": "1851022 Fudge, Tyler", "bounds_geometry": ["POINT(123.33 -75.09)"], "date_created": "Fri, 22 Dec 2023 00:00:00 GMT", "description": "Volcanic deposition of sulfuric acid in ice cores is important both for understanding past volcanic activity and for synchronizing ice core timescales. Sulfuric acid has a low eutectic point, so it can potentially exist in liquid at grain boundaries and veins, accelerating chemical diffusion. A high effective diffusivity would allow post-depositional diffusion to obscure the climate history and the peak matching among older portions of ice cores. Here, we use records of sulfate from the EPICA Dome C (EDC) ice core to estimate the effective diffusivity of sulfuric acid in ice. We focus on EDC because multiple glacial-interglacial cycles are preserved, allowing analysis for long timescales and deposition in similar climates. We calculate the mean concentration gradient and the width of prominent volcanic events, and analyze the evolution of each with depth/age. We find the effective diffusivities for interglacials and glacial maximums to be 5 \u00b1 3 \u00d7 10-9 m2 a-1, an order of magnitude lower than a previous estimate derived from the Holocene portion of EDC (Barnes et al., 2003). The effective diffusivity may be even smaller if the bias from artificial smoothing from the sampling is accounted for. Effective diffusivity is not obviously affected by the ice temperature until about -10\u00b0C, 3000m depth, which is also where anomalous sulfate peaks begin to be observed (Traversi et al., 2009). Low effective diffusivity suggests that sulfuric acid is not readily diffusing in liquid-like veins in the upper portions of the Antarctic ice sheet and that records may be preserved in deep, old ice if the ice temperature remains well below the pressure melting point.", "east": 123.33, "geometry": ["POINT(123.33 -75.09)"], "keywords": "Antarctica", "locations": "Antarctica", "north": -75.09, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Fudge, T. J.; Severi, Mirko", "project_titles": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation", "projects": [{"proj_uid": "p0010211", "repository": "USAP-DC", "title": "Collaborative Research: The Impact of Impurities and Stress State on Polycrystalline Ice Deformation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "COLDEX", "south": -75.09, "title": "EPICA Dome C Sulfate Data 7-3190m", "uid": "601759", "west": 123.33}, {"awards": "2013987 Zoet, Lucas", "bounds_geometry": null, "date_created": "Wed, 13 Dec 2023 00:00:00 GMT", "description": "This dataset contains AMS results and microstructure analysis from different depths within the sheared till.", "east": null, "geometry": null, "keywords": "Antarctica", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Zoet, Lucas", "project_titles": "Collaborative Research: Freeze-on of Subglacial Sediments in Experiments and Theory", "projects": [{"proj_uid": "p0010434", "repository": "USAP-DC", "title": "Collaborative Research: Freeze-on of Subglacial Sediments in Experiments and Theory"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Ring shear bed deformation measurements", "uid": "601757", "west": null}, {"awards": "1245871 McCarthy, Christine", "bounds_geometry": null, "date_created": "Thu, 23 Dec 2021 00:00:00 GMT", "description": "This data set contains text files for the experimental logs of ice-on-rock friction experiments that were conducted in a double direct shear apparatus at temperatures of -16.4 C to -2 C. There are eleven files (C28-C34, C39-C41, and C44). Each file contains 4 columns of data that correspond to time (s), vertical displacement (microns), friction, and velocity. The data were prepared by converting voltages from experimental feedbacks, to appropriate units using calibrations, as conducted separate. Miscellaneous loading and unloading data were removed and the data was filtered modestly (100 point moving average filter in matlab). The data set includes all information needed to plot friction or velocity vs. time or displacement from the beginning to end of the run. ", "east": null, "geometry": null, "keywords": "Antarctica", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "McCarthy, Christine M.; Skarbek, Rob; Savage, Heather", "project_titles": "Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers", "projects": [{"proj_uid": "p0010186", "repository": "USAP-DC", "title": "Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Dataset for Tidal modulation of ice streams: Effect of periodic sliding velocity on ice friction and healing", "uid": "601497", "west": null}, {"awards": "1245871 McCarthy, Christine", "bounds_geometry": null, "date_created": "Fri, 30 Jul 2021 00:00:00 GMT", "description": "This data set contains rate and state frictional parameters for ice-on-rock friction experiments that were conducted in a double direct shear apparatus as temperatures of -16.4 C to -2 C. The frictional parameters were deteremined by directly fitting the frictional response to controlled, harmonic oscillations in load point velocity. The data set includes all information needed to reproduce the fits, as well as tables of the frictional parameters for both the aging and slip law forms of frictional state evolution.", "east": null, "geometry": null, "keywords": "Antarctica", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Skarbek, Rob; McCarthy, Christine M.; Savage, Heather", "project_titles": "Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers", "projects": [{"proj_uid": "p0010186", "repository": "USAP-DC", "title": "Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Rate-state friction parameters for ice-on-rock oscillation experiments", "uid": "601467", "west": null}, {"awards": "0440670 Hulbe, Christina", "bounds_geometry": ["POLYGON((-180 -77,-177 -77,-174 -77,-171 -77,-168 -77,-165 -77,-162 -77,-159 -77,-156 -77,-153 -77,-150 -77,-150 -77.9,-150 -78.8,-150 -79.7,-150 -80.6,-150 -81.5,-150 -82.4,-150 -83.3,-150 -84.2,-150 -85.1,-150 -86,-153 -86,-156 -86,-159 -86,-162 -86,-165 -86,-168 -86,-171 -86,-174 -86,-177 -86,180 -86,177.5 -86,175 -86,172.5 -86,170 -86,167.5 -86,165 -86,162.5 -86,160 -86,157.5 -86,155 -86,155 -85.1,155 -84.2,155 -83.3,155 -82.4,155 -81.5,155 -80.6,155 -79.7,155 -78.8,155 -77.9,155 -77,157.5 -77,160 -77,162.5 -77,165 -77,167.5 -77,170 -77,172.5 -77,175 -77,177.5 -77,-180 -77))"], "date_created": "Fri, 19 Feb 2021 00:00:00 GMT", "description": "The surface of the Ross Ice Shelf (RIS) is textured by flow stripes, crevasses and other fea- tures related to ice flow and deformation. Here, moderate resolution optical satellite images are used to map and classify regions of the RIS characterized by different surface textures. Because the textures arise from ice deformation, the map is used to identify structural provinces with common deformation history. We classify four province types: regions associated with large outlet glaciers, shear zones, exten- sion downstream of obstacles and suture zones between provinces with different upstream sources. Adjacent provinces with contrasting histories are in some locations deforming at different rates, suggest- ing that our province map is also an ice fabric map. Structural provinces have more complicated shapes in the part of the ice shelf fed by West Antarctic ice streams than in the part fed by outlet glaciers from the Transantarctic Mountains. The map may be used to infer past variations in stress conditions and flow events that cannot be inferred from flow traces alone.", "east": 155.0, "geometry": ["POINT(-177.5 -81.5)"], "keywords": "Antarctica", "locations": "Antarctica", "north": -77.0, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Hulbe, Christina; Ledoux, Christine; Forbes, Martin", "project_titles": "Collaborative Research: Using Fracture Patterns and Ice Thickness to Study the History and Dynamics of Grounding Line Migration and Shutdown of Kamb and Whillans Ice Streams", "projects": [{"proj_uid": "p0000096", "repository": "USAP-DC", "title": "Collaborative Research: Using Fracture Patterns and Ice Thickness to Study the History and Dynamics of Grounding Line Migration and Shutdown of Kamb and Whillans Ice Streams"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -86.0, "title": "MOA-derived Structural Feature Map of the Ross Ice Shelf", "uid": "601432", "west": -150.0}, {"awards": "1142167 Pettit, Erin", "bounds_geometry": ["POINT(-180 -90)"], "date_created": "Mon, 04 May 2020 00:00:00 GMT", "description": "Acoustic Televiewer measures borehole shape and tilt. These data were collected to study detailed borehole deformation with respect to ice properties to expand our understanding of the flow law for ice. ", "east": -180.0, "geometry": ["POINT(-180 -90)"], "keywords": "Acoustic Televiewer; Anisotropy; Antarctica; Borehole Logging; Deformation; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Ice Flow; Snow/ice; Snow/Ice; South Pole; SPICEcore", "locations": "South Pole; Antarctica", "north": -90.0, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Pettit, Erin", "project_titles": "Collaborative Research: VeLveT Ice - eVoLution of Fabric and Texture in Ice at WAIS Divide, West Antarctica", "projects": [{"proj_uid": "p0010098", "repository": "USAP-DC", "title": "Collaborative Research: VeLveT Ice - eVoLution of Fabric and Texture in Ice at WAIS Divide, West Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "SPICEcore", "south": -90.0, "title": "South Pole (SPICEcore) Borehole Deformation", "uid": "601315", "west": -180.0}, {"awards": "0732804 McPhee, Miles", "bounds_geometry": ["POINT(166.25 -77.42)"], "date_created": "Wed, 01 Jan 2014 00:00:00 GMT", "description": "The Office of Polar Programs, Antarctic Integrated and System Science Program has made this award to support an interdisciplinary study of the effects of the ocean on the stability of glacial ice in the most dynamic region the West Antarctic Ice Sheet, namely the Pine Island Glacier in the Amundsen Sea Embayment. The collaborative project builds on the knowledge gained by the highly successful West Antarctic Ice Sheet program and is being jointly sponsored with NASA. Recent observations indicate a significant ice loss, equivalent to 10% of the ongoing increase in sea-level rise, in this region. These changes are largest along the coast and propagate rapidly inland, indicating the critical impact of the ocean on ice sheet stability in the region. While a broad range of remote sensing and ground-based instrumentation is available to characterize changes of the ice surface and internal structure (deformation, ice motion, melt) and the shape of the underlying sediment and rock bed, instrumentation has yet to be successfully deployed for observing boundary layer processes of the ocean cavity which underlies the floating ice shelf and where rapid melting is apparently occurring. Innovative, mini ocean sensors that can be lowered through boreholes in the ice shelf (about 500 m thick) will be developed and deployed to automatically provide ocean profiling information over at least three years. Their data will be transmitted through a conducting cable frozen in the borehole to the surface where it will be further transmitted via satellite to a laboratory in the US. Geophysical and remote sensing methods (seismic, GPS, altimetry, stereo imaging, radar profiling) will be applied to map the geometry of the ice shelf, the shape of the sub ice-shelf cavity, the ice surface geometry and deformations within the glacial ice. To integrate the seismic, glaciological and oceanographic observations, a new 3-dimensional coupled ice-ocean model is being developed which will be the first of its kind. NASA is supporting satellite based research and the deployment of a robotic-camera system to explore the environment in the ocean cavity underlying the ice shelf and NSF is supporting all other aspects of this study. \n\nBroader impacts: This project is motivated by the potential societal impacts of rapid sea level rise and should result in critically needed improvements in characterizing and predicting the behavior of coupled ocean-ice systems. It is a contribution to the International Polar Year and was endorsed by the International Council for Science as a component of the \u0027Multidisciplinary Study of the Amundsen Sea Embayment\u0027 proposal #258 of the honeycomb of endorsed IPY activities. The research involves substantial international partnerships with the British Antarctic Survey and the University of Bristol in the UK. The investigators will partner with the previously funded \u0027Polar Palooza\u0027 education and outreach program in addition to undertaking a diverse set of outreach activities of their own. Eight graduate students and one undergraduate as well as one post doc will be integrated into this research project.\n", "east": 166.25, "geometry": ["POINT(166.25 -77.42)"], "keywords": "Antarctica; Atmosphere; McMurdo; Meteorology; Oceans; Ross Island; Southern Ocean", "locations": "Ross Island; Antarctica; McMurdo; Southern Ocean", "north": -77.42, "nsf_funding_programs": null, "persons": "McPhee, Miles G.", "project_titles": "Collaborative Research; IPY: Ocean-Ice Interaction in the Amundsen Sea sector of West Antarctica", "projects": [{"proj_uid": "p0000043", "repository": "USAP-DC", "title": "Collaborative Research; IPY: Ocean-Ice Interaction in the Amundsen Sea sector of West Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.42, "title": "Ocean-Ice Interaction in the Amundsen Sea Sector of West Antarctica", "uid": "600072", "west": 166.25}, {"awards": "0440523 Baker, Ian; 0538195 Marone, Chris; 0424589 Gogineni, S. Prasad", "bounds_geometry": ["POINT(-147.753056 61.781667)", "POINT(-83.006944 40.067222)", "POINT(147.758889 61.779444)"], "date_created": "Wed, 14 Apr 2010 00:00:00 GMT", "description": "This data set includes the results of laboratory experiments examining the constitutive properties of subglacial till, under dynamic stressing. The data include the results of shear strain and stress experiments. Testing was carried out in a servo-controlled biaxial shear device under controlled temperature and stress conditions, allowing both sliding and microstructural processes to be studied in detail. Till samples were collected from Matanuska, Alaska and from Caesar till at the Laurentide Ice Sheet. \n\nThe data are available via FTP in ASCII text format (.txt).", "east": 147.758889, "geometry": ["POINT(-147.753056 61.781667)", "POINT(-83.006944 40.067222)", "POINT(147.758889 61.779444)"], "keywords": "Geology/Geophysics - Other; Glaciers/ice Sheet; Glaciers/Ice Sheet; Shear Stress; Solid Earth; Strain", "locations": null, "north": 61.781667, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Marone, Chris; Anandakrishnan, Sridhar", "project_titles": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till", "projects": [{"proj_uid": "p0000554", "repository": "USAP-DC", "title": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": 40.067222, "title": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till", "uid": "609460", "west": -147.753056}, {"awards": "0228842 Grew, Edward", "bounds_geometry": ["POLYGON((76 -69.3,76.05 -69.3,76.1 -69.3,76.15 -69.3,76.2 -69.3,76.25 -69.3,76.3 -69.3,76.35 -69.3,76.4 -69.3,76.45 -69.3,76.5 -69.3,76.5 -69.32,76.5 -69.34,76.5 -69.36,76.5 -69.38,76.5 -69.4,76.5 -69.42,76.5 -69.44,76.5 -69.46,76.5 -69.48,76.5 -69.5,76.45 -69.5,76.4 -69.5,76.35 -69.5,76.3 -69.5,76.25 -69.5,76.2 -69.5,76.15 -69.5,76.1 -69.5,76.05 -69.5,76 -69.5,76 -69.48,76 -69.46,76 -69.44,76 -69.42,76 -69.4,76 -69.38,76 -69.36,76 -69.34,76 -69.32,76 -69.3))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a project to investigate the role and fate of Boron in high-grade metamorphic rocks of the Larsemann Hills region of Antarctica. Trace elements provide valuable information on the changes sedimentary rocks undergo as temperature and pressure increase during burial. One such element, boron, is particularly sensitive to increasing temperature because of its affinity for aqueous fluids, which are lost as rocks are buried. Boron contents of unmetamorphosed pelitic sediments range from 20 to over 200 parts per million, but rarely exceed 5 parts per million in rocks subjected to conditions of the middle and lower crust, that is, temperatures of 700 degrees C or more in the granulite-facies, which is characterized by very low water activities at pressures of 5 to 10 kbar (18-35 km burial). Devolatization reactions with loss of aqueous fluid and partial melting with removal of melt have been cited as primary causes for boron depletion under granulite-facies conditions. Despite the pervasiveness of both these processes, rocks rich in boron are locally found in the granulite-facies, that is, there are mechanisms for retaining boron during the metamorphic process. The Larsemann Hills, Prydz Bay, Antarctica, are a prime example. More than 20 lenses and layered bodies containing four borosilicate mineral species crop out over a 50 square kilometer area, which thus would be well suited for research on boron-rich granulite-facies metamorphic rocks. While most investigators have focused on the causes for loss of boron, this work will investigate how boron is retained during high-grade metamorphism. Field observations and mapping in the Larsemann Hills, chemical analyses of minerals and their host rocks, and microprobe age dating will be used to identify possible precursors and deduce how the precursor materials recrystallized into borosilicate rocks under granulite-facies conditions. \n\nThe working hypothesis is that high initial boron content facilitates retention of boron during metamorphism because above a certain threshold boron content, a mechanism \u0027kicks in\u0027 that facilitates retention of boron in metamorphosed rocks. For example, in a rock with large amounts of the borosilicate tourmaline, such as stratabound tourmalinite, the breakdown of tourmaline to melt could result in the formation of prismatine and grandidierite, two borosilicates found in the Larsemann Hills. This situation is rarely observed in rocks with modest boron content, in which breakdown of tourmaline releases boron into partial melts, which in turn remove boron when they leave the system. Stratabound tourmalinite is associated with manganese-rich quartzite, phosphorus-rich rocks and sulfide concentrations that could be diagnostic for recognizing a tourmalinite protolith in a highly metamorphosed complex where sedimentary features have been destroyed by deformation. Because partial melting plays an important role in the fate of boron during metamorphism, our field and laboratory research will focus on the relationship between the borosilicate units, granite pegmatites and other granitic intrusives. The results of our study will provide information on cycling of boron at deeper levels in the Earth\u0027s crust and on possible sources of boron for granites originating from deep-seated rocks. An undergraduate student will participate in the electron microprobe age-dating of monazite and xenotime as part of a senior project, thereby integrating the proposed research into the educational mission of the University of Maine. In response to a proposal for fieldwork, the Australian Antarctic Division, which maintains Davis station near the Larsemann Hills, has indicated that they will support the Antarctic fieldwork.", "east": 76.5, "geometry": ["POINT(76.25 -69.4)"], "keywords": "Antarctica; Chemistry:rock; Chemistry:Rock; Geochemistry; Geochronology; Solid Earth", "locations": "Antarctica", "north": -69.3, "nsf_funding_programs": null, "persons": "Grew, Edward", "project_titles": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?", "projects": [{"proj_uid": "p0000431", "repository": "USAP-DC", "title": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -69.5, "title": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?", "uid": "600030", "west": 76.0}, {"awards": "0538195 Marone, Chris", "bounds_geometry": null, "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This award supports a project to conduct laboratory experiments and numerical modeling to determine the constitutive properties of subglacial till under dynamic stressing and to test the hypothesis that granular properties of till are sufficient, when coupled elastically to a large ice stream, to reproduce the field observations of triggered slip and subglacial seismicity. Testing will be carried out in a servo-controlled biaxial shear device under controlled temperature and stress conditions, which will allow both sliding and microstructural processes to be studied in detail. The main focus of the work will be on laboratory measurements. In addition, we will construct continuum models to evaluate whether our results can predict complex ice sheet motions and observed characteristics of subglacial seismicity. In terms of broader impacts, the proposed work will encourage interactions between the rock-mechanics and glaciology communities and will bring together members of different scientific backgrounds and vocabularies, but similar problems and data. The project will train undergraduate and graduate students at Penn State University and the scientists involved plan to give presentations to grade school classes, scout groups, and at community open houses. Results will be presented at professional meetings and will be published in a timely manner. The work will result in a better understanding of glacial motion and the physics of earthquake slip, which is essential for understanding ice sheet dynamics and earthquake hazard.", "east": null, "geometry": null, "keywords": "Antarctica; Glacial Till; Glaciers/ice Sheet; Glaciers/Ice Sheet; Lab Experiment; Marine Sediments; Physical Properties; Solid Earth", "locations": "Antarctica", "north": null, "nsf_funding_programs": null, "persons": "Marone, Chris; Anandakrishnan, Sridhar", "project_titles": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till", "projects": [{"proj_uid": "p0000554", "repository": "USAP-DC", "title": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till", "uid": "600054", "west": null}, {"awards": "9615502 Harrison, William", "bounds_geometry": ["POINT(-148.822 -81.655)", "POINT(-148.693 -81.595)"], "date_created": "Thu, 22 Feb 2007 00:00:00 GMT", "description": "At the Siple Dome area of Antarctica, much of the ice flow is vertical, which causes vertical ice deformation. To measure this phenomenon, the investigators used a method known as vertical strain rate. This project was a part of the West Antarctic Ice Sheet Cores (WAISCORES) project for deep ice coring in West Antarctica. WAISCORES is supported by the Office of Polar Programs (OPP), National Science Foundation (NSF).\n\nThis data set consists of a table of long-term average strain rates measured between 1999 and 2002 at Siple Dome, Antarctica. The measurements were taken in hot-water boreholes by bridge gauges. Data are available in tab-delimited ASCII text format or PDF via FTP.", "east": -148.693, "geometry": ["POINT(-148.822 -81.655)", "POINT(-148.693 -81.595)"], "keywords": "Antarctica; Geodesy; Geology/Geophysics - Other; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Siple Dome; Siple Dome Ice Core; Strain; WAISCORES", "locations": "Siple Dome; Antarctica", "north": -81.595, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Harrison, William; Morack, James; Waddington, Edwin D.; Pettit, Erin; Zumberge, Mark; Elsberg, Daniel", "project_titles": "Ice Dynamics, the Flow Law, and Vertical Strain at Siple Dome", "projects": [{"proj_uid": "p0000601", "repository": "USAP-DC", "title": "Ice Dynamics, the Flow Law, and Vertical Strain at Siple Dome"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Siple Dome Ice Core", "south": -81.655, "title": "Vertical Strain at Siple Dome, Antarctica, 1999-2002", "uid": "609214", "west": -148.822}, {"awards": "0135989 Wilen, Larry", "bounds_geometry": ["POINT(148 81)"], "date_created": "Wed, 02 Mar 2005 00:00:00 GMT", "description": "This data set contains measurements of the orientation and deformation of the crystal c-axes (fabric) of ice core samples collected from the Siple Dome Ice Core A, Antarctica (81\u00b0S, 148\u00b0W) between 22.764 m and 992.385 m in depth. The instrument used for the measurements consists of a fiber-optic white light source, one fixed black-and-white video camera, and four rotation stages. The data are in ASCII tab-delimited text format and are available via FTP.", "east": 148.0, "geometry": ["POINT(148 81)"], "keywords": "Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Siple Dome; Siple Dome Ice Core", "locations": "Siple Dome; Antarctica", "north": 81.0, "nsf_funding_programs": "Antarctic Glaciology", "persons": "Wilen, Larry", "project_titles": "Collaborative Research: Fabric and Texture Characteristics of Micro-Physical Processes in Ice", "projects": [{"proj_uid": "p0000134", "repository": "USAP-DC", "title": "Collaborative Research: Fabric and Texture Characteristics of Micro-Physical Processes in Ice"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "Siple Dome Ice Core", "south": 81.0, "title": "Ice Fabric Characteristics: Siple Dome, A Core", "uid": "609255", "west": 148.0}]

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