USAP-DC

{"dp_type": "Project", "free_text": "TECTONIC PROCESSES"}

[{"awards": "2201129 Fischer, Karen", "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, 14 Jun 2022 00:00:00 GMT", "description": "The western portion of the Antarctic continent is active in terms of plate tectonic processes that can produce significant variations in the Earth\u0027s mantle temperature as well as partial melting of the mantle. In addition to these internal processes, the ice sheet in western Antarctica is melting due to Earth\u0027s warming climate and adding water to the ocean. These changes in ice mass cause adjustments in rocks within the Earth\u0027s crust, allowing the surface to rebound in some locations and fall in others, altering the geographical pattern of sea-level change. However, the solid Earth response depends strongly on the strength of the rocks at a wide range of timescales which is not well-known and varies with temperature and other rock properties. This project has three primary goals. (1) It will assess how processes such as rifting, mantle upwelling and lithospheric instability have altered the lithosphere and underlying asthenosphere of western Antarctica, contributing to a planet-wide understanding of these processes. (2) It will use new measurements of mantle and crust properties to estimate the rate at which heat from the solid Earth flows into the base of the ice, which is important for modeling the rates at which the ice melts and flows. (3) It will places bounds on mantle viscosity, which is key for modeling the interaction of the solid Earth with changing ice and water masses and their implications for sea-level rise. To accomplish these goals, new resolution of crust and mantle structure will be obtained by analyzing seismic waves from distant earthquakes that have been recorded at numerous seismic stations in Antarctica. These analyses will include new combinations of seismic wave data that provide complementary information about mantle temperature, heat flow and viscosity. \u003cbr\u003e\u003cbr\u003eTechnical Description: This research addresses key questions about mantle processes and properties in western Antarctica. What are the relative impacts of rifting, mantle plumes, and lithospheric delamination in the evolution of the lithosphere and asthenosphere? Where is topography isostatically compensated, and where are dynamic processes such as plate flexure or tractions from 3-D mantle flow required? What are the bounds on heat flow and mantle viscosity, which represent important inputs to models of ice sheet evolution and its feedback from the solid Earth? To address these questions, this project will measure mantle and crust properties using seismic tools that have not yet been applied in Antarctica: regional-scale measurement of mantle attenuation from surface waves; Sp body wave phases to image mantle velocity gradients such as the lithosphere-asthenosphere boundary; and surface wave amplification and ellipticity. The resulting models of seismic attenuation and velocity will be jointly interpreted to shed new light on temperature, bulk composition, volatile content, and partial melt, using a range of laboratory-derived constitutive laws, while considering data from mantle xenoliths. To test the relative roles of rifting, mantle plumes, and delamination, and to assess isostatic support for Antarctic topography, the predictions of these processes will be compared to the new models of crust and mantle properties. To improve bounds on western Antarctic heat flow, seismic attenuation and velocity will be used in empirical comparisons and in direct modeling of vertical temperature gradients. To better measure mantle viscosity at the timescales of glacial isostatic adjustment, frequency-dependent viscosity will be estimated from the inferred mantle conditions. \u003cbr\u003e\u003cbr\u003eThis project will contribute to the education and career development of a Brown University Ph.D. student, Brown undergraduates, and undergraduates from outside the university who will be involved through the Department of Earth, Environmental and Planetary Sciences (DEEPS) Leadership Alliance NSF Research Experience for Undergraduates (REU) Site which focuses on geoscience summer research experiences for underrepresented students. The project will be the basis for a seminar at Brown that explores the connections between the solid Earth and cryosphere in Antarctica and will contribute to outreach in local public elementary and high schools.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e SEISMOMETERS \u003e SEISMOGRAPHS", "is_usap_dc": true, "keywords": "USAP-DC; West Antarctica; USA/NSF; SEISMIC SURFACE WAVES; AMD; PLATE TECTONICS; Amd/Us; GLACIERS/ICE SHEETS; FIELD INVESTIGATION", "locations": "West Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Fischer, Karen; Dalton, Colleen", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repositories": null, "science_programs": null, "south": -90.0, "title": "Probing the Western Antarctic Lithosphere and Asthenosphere with New Approaches to Imaging Seismic Wave Attenuation and Velocity", "uid": "p0010339", "west": -180.0}, {"awards": "1246111 Dalziel, Ian", "bounds_geometry": "POLYGON((-44 -53,-42.9 -53,-41.8 -53,-40.7 -53,-39.6 -53,-38.5 -53,-37.4 -53,-36.3 -53,-35.2 -53,-34.1 -53,-33 -53,-33 -53.4,-33 -53.8,-33 -54.2,-33 -54.6,-33 -55,-33 -55.4,-33 -55.8,-33 -56.2,-33 -56.6,-33 -57,-34.1 -57,-35.2 -57,-36.3 -57,-37.4 -57,-38.5 -57,-39.6 -57,-40.7 -57,-41.8 -57,-42.9 -57,-44 -57,-44 -56.6,-44 -56.2,-44 -55.8,-44 -55.4,-44 -55,-44 -54.6,-44 -54.2,-44 -53.8,-44 -53.4,-44 -53))", "dataset_titles": "BAS Geological Collection: Central Scotia Sea (full data link not provided); Nathaniel B Palmer NBP 1408; South Georgia: SOG1, SOG2, SOG3", "datasets": [{"dataset_uid": "200105", "doi": "", "keywords": null, "people": null, "repository": "UNAVCO", "science_program": null, "title": "South Georgia: SOG1, SOG2, SOG3", "url": "https://www.unavco.org/data/gps-gnss/gps-gnss.html"}, {"dataset_uid": "200107", "doi": "", "keywords": null, "people": null, "repository": "British Antarctic Survey", "science_program": null, "title": "BAS Geological Collection: Central Scotia Sea (full data link not provided)", "url": "https://www.bas.ac.uk/data/our-data/collections/geological-collections/"}, {"dataset_uid": "200106", "doi": "", "keywords": null, "people": null, "repository": "MGDS", "science_program": null, "title": "Nathaniel B Palmer NBP 1408", "url": "http://www.marine-geo.org/tools/search/entry.php?id=NBP1408"}], "date_created": "Tue, 28 Jan 2020 00:00:00 GMT", "description": "Intellectual Merit: \u003cbr/\u003eOpening of Drake Passage and the West Scotia Sea south of Tierra del Fuego broke the final continental barrier to onset of a complete Antarctic Circumpolar Current (ACC). Initiation of the ACC has been associated in time with a major, abrupt, drop in global temperatures and the rapid expansion of the Antarctic ice sheets at 33-34 Ma. Events leading to the formation of the Drake Passage gateway are poorly known. Understanding the tectonic evolution of the floor of the Central Scotia Sea (CSS) and the North Scotia Ridge is a key to this understanding. Previous work has demonstrated that superimposed constructs formed a volcanic arc that likely blocked direct eastward flow from the Pacific to the Atlantic through the opening Drake Passage gateway as the active South Sandwich arc does today. The PIs propose a cruise to test, develop and refine, with further targeted mapping and dredging, their theory of CSS tectonics and the influence it had on the onset and development of the ACC. In addition they propose an installation of GPS receiver to test their paleogeographic reconstructions and determine whether South Georgia is moving as part of the South American plate. \u003cbr/\u003e\u003cbr/\u003eBroader impacts: \u003cbr/\u003eA graduate student will be involved in all stages of the research. Undergraduate students will also be involved as watch-standers. A community college teacher will participate in the cruise. The PIs will have a website on which there will be images of the actual ocean floor dredging in operation. The teacher will participate with web and outreach support through PolarTREC. Results of the cruise are of broad interest to paleoceanographers, paleoclimate modelers and paleobiogeographers.A network of four continuous Global Navigational Satellite Systems (GNSS) receivers was installed on the bedrock of South Georgia in the Southern Ocean in 2013 and 2014. An additional receiver on a concrete foundation provides a tie to a tide gauge, part of the United Kingdom South Atlantic Tide Gauge Network. The GNSS receivers have already provided data suggesting that the South Georgia microcontinent (SGM) is moving independent of both the South American plate to the north and the Scotia plate to the south. The data also demonstrate that the SGM is being uplifted. ", "east": -33.0, "geometry": "POINT(-38.5 -55)", "instruments": "NOT APPLICABLE \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "is_usap_dc": true, "keywords": "Scotia Sea; PLATE BOUNDARIES; TECTONIC PROCESSES; NOT APPLICABLE; COASTAL ELEVATION; Southern Ocean; USAP-DC", "locations": "Scotia Sea; Southern Ocean", "north": -53.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Glaciology", "paleo_time": null, "persons": "Dalziel, Ian W.; Lawver, Lawrence; Krissek, Lawrence", "platforms": "OTHER \u003e NOT APPLICABLE \u003e NOT APPLICABLE", "repo": "UNAVCO", "repositories": "British Antarctic Survey; MGDS; UNAVCO", "science_programs": null, "south": -57.0, "title": "Collaborative Research: Role of the Central Scotia Sea Floor and North Scotia Ridge in the Onset and Development of the Antarctic Circumpolar Current", "uid": "p0010078", "west": -44.0}, {"awards": "9317588 Lawver, Lawrence", "bounds_geometry": null, "dataset_titles": "Expedition Data; Expedition data of NBP9507", "datasets": [{"dataset_uid": "002227", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP9507"}, {"dataset_uid": "002590", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP9507", "url": "https://www.rvdata.us/search/cruise/NBP9507"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "This award supports a marine geophysical investigation of the Bransfield Strait and the Shackleton Fracture Zone and environs in the Scotia Sea in an effort to understand the neotectonic evolution of the region. Multibeam swath mapping and sidescan sonar mapping will be used along with multichannel seismic imaging. The main goal of this proposal is to collect multibeam and sidescan sonar data to map the structural character and tectonic fabric of the evolving plate boundary in Southwest Scotia Sea, Shackleton Fracture Zone, and Bransfield Strait. Follow up multichannel seismic surveys will be done in the Southwest Scotia Sea. The secondary goal is to use sidescan sonar reflectivity images to generate detailed structural maps of the seafloor of these regions and to integrate the new data with existing seismic reflection, Geosat gravity, Hydrosweep and Seabeam bathymetric data. Once the base maps are produced they can be used by other researchers to help interpret multichannel and single channel seismic reflection records. The neotectonic evolution of the Antarctic Peninsula and Scotia Sea is extremely complex. Understanding the recent evolution of the Drake-Scotia-Antarctic-South America plate intersections will provide important information as to how major plate boundaries reorganize after demise of a long-lived spreading center and the consequential reduction in the number of plates. The plate reorganization probably resulted in the uplift of the Shackleton Ridge which may have effected the sedimentary patterns in both the Scotia Sea and possibly the Weddell Sea. If the break of the Shackleton transform fault can be traced with multibeam and sidescan sonar as it intersects the southern end of South America then the orientation and geometry of the faults, fractures and deformation as the transform fault intersects the South American continent will help to interpret the structures in that complex region. Bransfield Strait is presently undergoing extensi on based on high heat flow, active volcanoes and inferences from seismic reflection work. Seismic refraction indicates thick crust similar to the East African Rift or passive volcanic margins of continents. In contrast, analysis of isotopes and rare earth elements of the recent volcanics shows seemingly no continental contamination. The active extension in Bransfield Strait must be related to the plate reorganization but it is unclear exactly what tectonic processes are occurring. Besides elucidating the tectonic fabric of Bransfield Strait, the multibeam and sidescan sonar survey will identify potential dredge targets and DSRV Alvin dive sites.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS", "is_usap_dc": false, "keywords": "R/V NBP", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Klinkhammer, Gary", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": null, "title": "Neotectonic Evolution of Antarctic Peninsula/Scotia Sea Region: Multi-Beam, Sidescan Sonar, Seismic, Magnetics and Gravity Studies", "uid": "p0000809", "west": null}]

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