{"dp_type": "Project", "free_text": "Magnetotelluric"}
[{"awards": "1443522 Wannamaker, Philip", "bounds_geometry": "POLYGON((166 -77.15,166.34 -77.15,166.68 -77.15,167.02 -77.15,167.36 -77.15,167.7 -77.15,168.04 -77.15,168.38 -77.15,168.72 -77.15,169.06 -77.15,169.4 -77.15,169.4 -77.22500000000001,169.4 -77.30000000000001,169.4 -77.375,169.4 -77.45,169.4 -77.525,169.4 -77.60000000000001,169.4 -77.67500000000001,169.4 -77.75,169.4 -77.825,169.4 -77.9,169.06 -77.9,168.72 -77.9,168.38 -77.9,168.04 -77.9,167.7 -77.9,167.36 -77.9,167.02 -77.9,166.68 -77.9,166.34 -77.9,166 -77.9,166 -77.825,166 -77.75,166 -77.67500000000001,166 -77.60000000000001,166 -77.525,166 -77.45,166 -77.375,166 -77.30000000000001,166 -77.22500000000001,166 -77.15))", "dataset_titles": "Erebus volcano/Ross Island Magnetotelluric (MT) data", "datasets": [{"dataset_uid": "601493", "doi": "10.15784/601493", "keywords": "Antarctica; Mantle Melting; Mount Erebus", "people": "Hill, Graham; Wannamaker, Philip", "repository": "USAP-DC", "science_program": null, "title": "Erebus volcano/Ross Island Magnetotelluric (MT) data", "url": "https://www.usap-dc.org/view/dataset/601493"}], "date_created": "Mon, 05 Feb 2024 00:00:00 GMT", "description": "General Description: This project is intended to reveal the magma source regions, staging areas, and eruptive pathways within the active volcano Mount Erebus. This volcano is an end-member type known as phonolitic, which refers to the lava composition, and is almost purely carbon-dioxide-bearing and occurs in continental rift settings. It is in contrast to the better known water-bearing volcanoes which occur at plate boundary settings (such as Mount St Helens or Mount Fuji). Phonolitic volcanic eruptions elsewhere such as Tamboro or Vesuvius have caused more than 50,000 eruption related fatalities. Phonolites are also associated with rare earth element deposits, giving them economic interest. To illuminate the inner workings of Mount Erebus, we will cover the volcano with a dense network of geophysical probes based on magnetotelluric (MT) measurements. MT makes use of naturally occurring electromagnetic (EM) waves generated mainly by the sun as sources to provide images of the electrical conductivity structure of the Earth\u0027s interior. Conductivity is sensitive to the presence of fluids and melts in the Earth and so is well suited to understanding volcanic processes. The project is a cooperative effort between scientists from the United States, New Zealand, Japan and Canada. It implements new technology developed by the lead investigator and associates that allows such measurements to be taken on snow-covered terrains. This has applicability for frozen environments generally, such as resource exploration in the Arctic. The project supports a new post-doctoral researcher, and leverages imaging and measurement methods developed through support by other agencies and interfaced with commercial platforms. Technical Description: The investigators propose to test magmatic evolution models for Mount Erebus volcano, Antarctica, using the magnetotelluric (MT) method. The phonolite lava flow compositions on Mount Erebus are uncommon, but provide a window into the range of upper mantle source compositions and melt differentiation paths. Explosive phonolite eruptions have been known worldwide for devastating eruptions such as Tambora and Vesuvius, and commonly host rare earth element deposits. In the MT method, temporal variations in the Earth\u0027s natural electromagnetic (EM) field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 100 kilometers. This effort will consist of approximately 100 MT sites, with some concentration in the summit area. Field acquisition will take place over two field seasons. The main goals are to 1) confirm the existence and the geometry of the uppermost magma chamber thought to reside at 5-10 kilometer depths; 2) attempt to identify, in the deeper resistivity structure, the magma staging area near the crust-mantle boundary; 3) image the steep, crustal-scale, near-vertical conduit carrying magma from the mantle; 4) infer the physical and chemical state from geophysical properties of a CO2-dominated mafic shield volcano; and 5) constrain the relationships between structural and magmatic/ hydrothermal activity related to the Terror Rift. Tomographic imaging of the interior resistivity will be performed using a new inversion platform developed at Utah, based on the deformable edge finite element method, that is the best available for accommodating the steep topography of the study area. The project is an international cooperation between University of Utah, GNS Science Wellington New Zealand (G. Hill, Co-I), and Tokyo Institute of Technology Japan (Y. Ogawa, Co-I), plus participation by University of Alberta (M. Unsworth) and Missouri State University (K. Mickus). Instrument deployments will be made exclusively by helicopter. The project implements new technology that allows MT measurements to be taken on snow-covered terrains. The project supports a new post-doctoral researcher, and leverages imaging and measurement methods developed through support by other agencies and interfaced with commercial platforms.", "east": 169.4, "geometry": "POINT(167.7 -77.525)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS", "is_usap_dc": true, "keywords": "MAGNETIC FIELD; FIELD SURVEYS; Ross Island; Magnetotelluric; Mount Erebus", "locations": "Ross Island; Mount Erebus", "north": -77.15, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Wannamaker, Philip", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.9, "title": "Magma Sources, Residence and Pathways of Mount Erebus Phonolitic Volcano, Antarctica, from Magnetotelluric Resistivity Structure", "uid": "p0010444", "west": 166.0}, {"awards": "1643917 Fricker, Helen", "bounds_geometry": "POLYGON((-163.646 -84.186,-162.58715 -84.186,-161.5283 -84.186,-160.46945 -84.186,-159.4106 -84.186,-158.35175 -84.186,-157.2929 -84.186,-156.23405 -84.186,-155.1752 -84.186,-154.11635 -84.186,-153.0575 -84.186,-153.0575 -84.20871,-153.0575 -84.23142,-153.0575 -84.25413,-153.0575 -84.27684,-153.0575 -84.29955,-153.0575 -84.32226,-153.0575 -84.34497,-153.0575 -84.36768,-153.0575 -84.39039,-153.0575 -84.4131,-154.11635 -84.4131,-155.1752 -84.4131,-156.23405 -84.4131,-157.2929 -84.4131,-158.35175 -84.4131,-159.4106 -84.4131,-160.46945 -84.4131,-161.5283 -84.4131,-162.58715 -84.4131,-163.646 -84.4131,-163.646 -84.39039,-163.646 -84.36768,-163.646 -84.34497,-163.646 -84.32226,-163.646 -84.29955,-163.646 -84.27684,-163.646 -84.25413,-163.646 -84.23142,-163.646 -84.20871,-163.646 -84.186))", "dataset_titles": "Wideband magnetotelluric responses from Whillans Ice Stream, West Antarctica", "datasets": [{"dataset_uid": "601526", "doi": "10.15784/601526", "keywords": "Antarctica; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Ice Stream; Magnetotelluric; Subglacial; Whillans Ice Stream", "people": "Siegfried, Matthew; Key, Kerry; Gustafson, Chloe; Fricker, Helen", "repository": "USAP-DC", "science_program": null, "title": "Wideband magnetotelluric responses from Whillans Ice Stream, West Antarctica", "url": "https://www.usap-dc.org/view/dataset/601526"}], "date_created": "Sat, 26 Feb 2022 00:00:00 GMT", "description": "The Antarctic ice sheet is underlain by a dynamic water system that lubricates the flow of ice streams and outlet glaciers, provides a habitat for a diverse microbial ecosystem, and delivers freshwater and nutrients to the Southern Ocean. However, imaging this subglacial environment is difficult: Antarctica is a vast continent with ice up to four kilometers (2.5 miles) thick. To detect water at the ice-bed interface and in deeper groundwater reservoirs, this project will adapt a technique called electromagnetic sounding that is well-established on land and in the ocean for imaging fluids beneath the surface. Groundwater is estimated to be a significant part of the subglacial water budget in Antarctica, yet previous observational approaches have been unable to characterize its volume and distribution. This project will thus yield critical information about how ice-rock-water-ocean systems interact and inform our understanding of ice-sheet processes, global nutrient cycles, and freshwater flux to the ocean. The project will provide cross-disciplinary training for a graduate student and postdoctoral scientist, and develop an educational outreach program through the Birch Aquarium. Standard geophysical surveying techniques used in glaciology to image subglacial water (radio-echo sounding and active-source seismology) are not directly sensitive to water content. In contrast, ground-based electromagnetic (EM) methods are sensitive to water content through its impact on bulk conductivity. Although EM methods are well-established for high-precision mapping of hydrology in other geological environments, their application on ice sheets is in its infancy. The proposed work will adapt both passive- and active-source EM techniques to glaciological questions to quantify the three-dimensional structure of subglacial water beneath an ice stream and in a grounding zone. The project will perform a suite of synthetic inversion studies to determine the range of applications of EM techniques in glaciology and execute a field experiment on the Whillans Ice Plain to investigate two hypotheses about the subglacial water system based on previous observational and modeling results: (1) Subglacial Lake Whillans is underlain by a deep, saline groundwater reservoir; and (2) there is an estuary-like zone of mixing between fresh subglacial water and seawater near, and possibly landward, of the grounding line.", "east": -153.0575, "geometry": "POINT(-158.35175 -84.29955)", "instruments": null, "is_usap_dc": true, "keywords": "Whillans Ice Stream; GROUND WATER; USA/NSF; USAP-DC; AMD; GEOMAGNETIC INDUCTION; Amd/Us; FIELD SURVEYS", "locations": "Whillans Ice Stream", "north": -84.186, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Key, Kerry; Fricker, Helen; Siegfried, Matthew", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.4131, "title": "Mapping Antarctic Subglacial Water with Novel Electromagnetic Techniques", "uid": "p0010300", "west": -163.646}, {"awards": "0838914 Wannamaker, Philip", "bounds_geometry": "POLYGON((141.01732 -82.13,144.910279 -82.13,148.803238 -82.13,152.696197 -82.13,156.589156 -82.13,160.482115 -82.13,164.375074 -82.13,168.268033 -82.13,172.160992 -82.13,176.053951 -82.13,179.94691 -82.13,179.94691 -82.351835,179.94691 -82.57367,179.94691 -82.795505,179.94691 -83.01734,179.94691 -83.239175,179.94691 -83.46101,179.94691 -83.682845,179.94691 -83.90468,179.94691 -84.126515,179.94691 -84.34835,176.053951 -84.34835,172.160992 -84.34835,168.268033 -84.34835,164.375074 -84.34835,160.482115 -84.34835,156.589156 -84.34835,152.696197 -84.34835,148.803238 -84.34835,144.910279 -84.34835,141.01732 -84.34835,141.01732 -84.126515,141.01732 -83.90468,141.01732 -83.682845,141.01732 -83.46101,141.01732 -83.239175,141.01732 -83.01734,141.01732 -82.795505,141.01732 -82.57367,141.01732 -82.351835,141.01732 -82.13))", "dataset_titles": "Agglutinated Foraminifera, genome sequencing data; Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements", "datasets": [{"dataset_uid": "600102", "doi": "10.15784/600102", "keywords": "Antarctica; Magnetotelluric; Potential Field; Solid Earth; Transantarctic Mountains", "people": "Wannamaker, Philip", "repository": "USAP-DC", "science_program": null, "title": "Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements", "url": "https://www.usap-dc.org/view/dataset/600102"}, {"dataset_uid": "000211", "doi": "", "keywords": null, "people": null, "repository": "NCBI GenBank", "science_program": null, "title": "Agglutinated Foraminifera, genome sequencing data", "url": "http://www.ncbi.nlm.nih.gov/sites/myncbi/collections/public/1vwfrm7rJme2hrzl6smGVhpk-/"}], "date_created": "Mon, 12 Nov 2012 00:00:00 GMT", "description": "This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The investigators will examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains, and evolution of the thermal regimes of rifted West Antarctica and stable East Antarctica using magnetotelluric (MT) profiles. Surrounded almost entirely by ocean ridges, Antarctica is a special tectonic situation because of the need to make accommodation space for rifting in the Transantarctic region. In the MT method, temporal variations in the Earth\u0027s natural electromagnetic field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 200 km, or more. Geophysical methods, such as MT, are appropriate in Antarctica because of the predominance of thick ice cover over most of the Continent and the difficult operating environment. The proposed effort will consist of approximately 50 sites over a distance approaching 500 km with a 10 km average spacing, oriented normal to the Transantarctic Mountains (TAM), in the Beardmore glacier area. High quality MT soundings will be collected over thick ice sheets using a custom electrode preamp design, updated from previous Antarctic projects. Data acquisition will take place over two field seasons. The primary goals are three-fold: to establish the location of the deeper tectonic transition between East and West Antarctica that may be offset from the physiographic transition at the surface, using deep resistivity structure distinguish between modes of extensional upwelling and magmatism that may be vertically non-uniform, depth and magnitude of quasi-layered deep crustal low resistivity, particularly below West Antarctica, will be used to estimate crustal heat flux into the ice sheet base.", "east": 179.94691, "geometry": "POINT(160.482115 -83.239175)", "instruments": null, "is_usap_dc": true, "keywords": "Not provided", "locations": null, "north": -82.13, "nsf_funding_programs": "Antarctic Instrumentation and Support; Antarctic Earth Sciences", "paleo_time": null, "persons": "Bowser, Samuel; Wannamaker, Philip", "platforms": "Not provided", "repo": "USAP-DC", "repositories": "NCBI GenBank; USAP-DC", "science_programs": null, "south": -84.34835, "title": "Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements", "uid": "p0000247", "west": 141.01732}, {"awards": "9222121 Dalziel, Ian", "bounds_geometry": null, "dataset_titles": "Concentration and Isotopic Composition of O2 and N2 in Trapped Gases of the Vostok Ice Core", "datasets": [{"dataset_uid": "609107", "doi": "10.7265/N5862DCW", "keywords": "Antarctica; Chemistry:fluid; Chemistry:Fluid; Geochemistry; Glaciology; Ice Core Records; Lake Vostok; Paleoclimate; UPLC-Q-TOF; Vostok Ice Core", "people": "Bender, Michael", "repository": "USAP-DC", "science_program": null, "title": "Concentration and Isotopic Composition of O2 and N2 in Trapped Gases of the Vostok Ice Core", "url": "https://www.usap-dc.org/view/dataset/609107"}], "date_created": "Tue, 01 Jan 2002 00:00:00 GMT", "description": "This award supports an in situ and short traverse seismic reflection/refraction and magnetotelluric experiment in West Antarctica. This collaborative experiment involves four awards at four institutions. The four-fold purpose is 1) to investigate part of the Byrd Subglacial Basin, 2) to test techniques for this work that could be done in a long traverse, 3) to determine the viability of the magnetotelluric method on a thick (electrically resistive) ice sheet, and 4) to evaluate the relative merits of refraction with wide reflection versus reflection with narrow refraction seismic studies in imaging the lithosphere. The geophysical techniques that will be employed are capable of imaging the ice sheet, the continental lithosphere, and the upper mantle, as well as determining physical properties of parts of the lithosphere and mantle. Investigations of outcrop geology over the last thirty years in West Antarctica and the Transantarctic Mountains have lead to recent interpretations that the crust is made up of many different lithospheric blocks. Seismic reflection work is the only way to image the crust in detail and the refraction work is the only way to determine physical properties of the layers and blocks defined by the reflection work. The magnetotelluric work is scientifically risky because it may not yield useful information when used over the electrically resistive ice sheet; however, if it works it has the potential to image molten rock in the crust and upper mantle. In a continental rift region such as West Antarctica, the presence of melt in the lithosphere is likely and, if documented, has very important ramifications to ice sheet dynamics. Research work supported by this award is expected to provide constraints to models of a range of crustal processes from models of ice sheet dynamics to tectonic and kinematic models of lithospheric thinning and rifting.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e SPECTROMETERS/RADIOMETERS \u003e MASS SPECTROMETERS", "is_usap_dc": true, "keywords": "Isotope; Vostok; USAP-DC; Antarctica; Trapped Gases; Ice Core; Glaciology; Nitrogen; GROUND STATIONS", "locations": "Antarctica; Vostok", "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Bender, Michael; Dalziel, Ian W.", "platforms": "LAND-BASED PLATFORMS \u003e PERMANENT LAND SITES \u003e GROUND STATIONS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Collaborative Research: Seismic Traverse of the Byrd Subglacial Basin-Field Test", "uid": "p0000150", "west": null}]
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Project Title/Abstract/Map | NSF Award(s) | Date Created | PIs / Scientists | Dataset Links and Repositories | Abstract | Bounds Geometry | Geometry | Selected | Visible | |||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Magma Sources, Residence and Pathways of Mount Erebus Phonolitic Volcano, Antarctica, from Magnetotelluric Resistivity Structure
|
1443522 |
2024-02-05 | Wannamaker, Philip |
|
General Description: This project is intended to reveal the magma source regions, staging areas, and eruptive pathways within the active volcano Mount Erebus. This volcano is an end-member type known as phonolitic, which refers to the lava composition, and is almost purely carbon-dioxide-bearing and occurs in continental rift settings. It is in contrast to the better known water-bearing volcanoes which occur at plate boundary settings (such as Mount St Helens or Mount Fuji). Phonolitic volcanic eruptions elsewhere such as Tamboro or Vesuvius have caused more than 50,000 eruption related fatalities. Phonolites are also associated with rare earth element deposits, giving them economic interest. To illuminate the inner workings of Mount Erebus, we will cover the volcano with a dense network of geophysical probes based on magnetotelluric (MT) measurements. MT makes use of naturally occurring electromagnetic (EM) waves generated mainly by the sun as sources to provide images of the electrical conductivity structure of the Earth's interior. Conductivity is sensitive to the presence of fluids and melts in the Earth and so is well suited to understanding volcanic processes. The project is a cooperative effort between scientists from the United States, New Zealand, Japan and Canada. It implements new technology developed by the lead investigator and associates that allows such measurements to be taken on snow-covered terrains. This has applicability for frozen environments generally, such as resource exploration in the Arctic. The project supports a new post-doctoral researcher, and leverages imaging and measurement methods developed through support by other agencies and interfaced with commercial platforms. Technical Description: The investigators propose to test magmatic evolution models for Mount Erebus volcano, Antarctica, using the magnetotelluric (MT) method. The phonolite lava flow compositions on Mount Erebus are uncommon, but provide a window into the range of upper mantle source compositions and melt differentiation paths. Explosive phonolite eruptions have been known worldwide for devastating eruptions such as Tambora and Vesuvius, and commonly host rare earth element deposits. In the MT method, temporal variations in the Earth's natural electromagnetic (EM) field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 100 kilometers. This effort will consist of approximately 100 MT sites, with some concentration in the summit area. Field acquisition will take place over two field seasons. The main goals are to 1) confirm the existence and the geometry of the uppermost magma chamber thought to reside at 5-10 kilometer depths; 2) attempt to identify, in the deeper resistivity structure, the magma staging area near the crust-mantle boundary; 3) image the steep, crustal-scale, near-vertical conduit carrying magma from the mantle; 4) infer the physical and chemical state from geophysical properties of a CO2-dominated mafic shield volcano; and 5) constrain the relationships between structural and magmatic/ hydrothermal activity related to the Terror Rift. Tomographic imaging of the interior resistivity will be performed using a new inversion platform developed at Utah, based on the deformable edge finite element method, that is the best available for accommodating the steep topography of the study area. The project is an international cooperation between University of Utah, GNS Science Wellington New Zealand (G. Hill, Co-I), and Tokyo Institute of Technology Japan (Y. Ogawa, Co-I), plus participation by University of Alberta (M. Unsworth) and Missouri State University (K. Mickus). Instrument deployments will be made exclusively by helicopter. The project implements new technology that allows MT measurements to be taken on snow-covered terrains. The project supports a new post-doctoral researcher, and leverages imaging and measurement methods developed through support by other agencies and interfaced with commercial platforms. | POLYGON((166 -77.15,166.34 -77.15,166.68 -77.15,167.02 -77.15,167.36 -77.15,167.7 -77.15,168.04 -77.15,168.38 -77.15,168.72 -77.15,169.06 -77.15,169.4 -77.15,169.4 -77.22500000000001,169.4 -77.30000000000001,169.4 -77.375,169.4 -77.45,169.4 -77.525,169.4 -77.60000000000001,169.4 -77.67500000000001,169.4 -77.75,169.4 -77.825,169.4 -77.9,169.06 -77.9,168.72 -77.9,168.38 -77.9,168.04 -77.9,167.7 -77.9,167.36 -77.9,167.02 -77.9,166.68 -77.9,166.34 -77.9,166 -77.9,166 -77.825,166 -77.75,166 -77.67500000000001,166 -77.60000000000001,166 -77.525,166 -77.45,166 -77.375,166 -77.30000000000001,166 -77.22500000000001,166 -77.15)) | POINT(167.7 -77.525) | false | false | |||
Mapping Antarctic Subglacial Water with Novel Electromagnetic Techniques
|
1643917 |
2022-02-26 | Key, Kerry; Fricker, Helen; Siegfried, Matthew |
|
The Antarctic ice sheet is underlain by a dynamic water system that lubricates the flow of ice streams and outlet glaciers, provides a habitat for a diverse microbial ecosystem, and delivers freshwater and nutrients to the Southern Ocean. However, imaging this subglacial environment is difficult: Antarctica is a vast continent with ice up to four kilometers (2.5 miles) thick. To detect water at the ice-bed interface and in deeper groundwater reservoirs, this project will adapt a technique called electromagnetic sounding that is well-established on land and in the ocean for imaging fluids beneath the surface. Groundwater is estimated to be a significant part of the subglacial water budget in Antarctica, yet previous observational approaches have been unable to characterize its volume and distribution. This project will thus yield critical information about how ice-rock-water-ocean systems interact and inform our understanding of ice-sheet processes, global nutrient cycles, and freshwater flux to the ocean. The project will provide cross-disciplinary training for a graduate student and postdoctoral scientist, and develop an educational outreach program through the Birch Aquarium. Standard geophysical surveying techniques used in glaciology to image subglacial water (radio-echo sounding and active-source seismology) are not directly sensitive to water content. In contrast, ground-based electromagnetic (EM) methods are sensitive to water content through its impact on bulk conductivity. Although EM methods are well-established for high-precision mapping of hydrology in other geological environments, their application on ice sheets is in its infancy. The proposed work will adapt both passive- and active-source EM techniques to glaciological questions to quantify the three-dimensional structure of subglacial water beneath an ice stream and in a grounding zone. The project will perform a suite of synthetic inversion studies to determine the range of applications of EM techniques in glaciology and execute a field experiment on the Whillans Ice Plain to investigate two hypotheses about the subglacial water system based on previous observational and modeling results: (1) Subglacial Lake Whillans is underlain by a deep, saline groundwater reservoir; and (2) there is an estuary-like zone of mixing between fresh subglacial water and seawater near, and possibly landward, of the grounding line. | POLYGON((-163.646 -84.186,-162.58715 -84.186,-161.5283 -84.186,-160.46945 -84.186,-159.4106 -84.186,-158.35175 -84.186,-157.2929 -84.186,-156.23405 -84.186,-155.1752 -84.186,-154.11635 -84.186,-153.0575 -84.186,-153.0575 -84.20871,-153.0575 -84.23142,-153.0575 -84.25413,-153.0575 -84.27684,-153.0575 -84.29955,-153.0575 -84.32226,-153.0575 -84.34497,-153.0575 -84.36768,-153.0575 -84.39039,-153.0575 -84.4131,-154.11635 -84.4131,-155.1752 -84.4131,-156.23405 -84.4131,-157.2929 -84.4131,-158.35175 -84.4131,-159.4106 -84.4131,-160.46945 -84.4131,-161.5283 -84.4131,-162.58715 -84.4131,-163.646 -84.4131,-163.646 -84.39039,-163.646 -84.36768,-163.646 -84.34497,-163.646 -84.32226,-163.646 -84.29955,-163.646 -84.27684,-163.646 -84.25413,-163.646 -84.23142,-163.646 -84.20871,-163.646 -84.186)) | POINT(-158.35175 -84.29955) | false | false | |||
Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements
|
0838914 |
2012-11-12 | Bowser, Samuel; Wannamaker, Philip | This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The investigators will examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains, and evolution of the thermal regimes of rifted West Antarctica and stable East Antarctica using magnetotelluric (MT) profiles. Surrounded almost entirely by ocean ridges, Antarctica is a special tectonic situation because of the need to make accommodation space for rifting in the Transantarctic region. In the MT method, temporal variations in the Earth's natural electromagnetic field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 200 km, or more. Geophysical methods, such as MT, are appropriate in Antarctica because of the predominance of thick ice cover over most of the Continent and the difficult operating environment. The proposed effort will consist of approximately 50 sites over a distance approaching 500 km with a 10 km average spacing, oriented normal to the Transantarctic Mountains (TAM), in the Beardmore glacier area. High quality MT soundings will be collected over thick ice sheets using a custom electrode preamp design, updated from previous Antarctic projects. Data acquisition will take place over two field seasons. The primary goals are three-fold: to establish the location of the deeper tectonic transition between East and West Antarctica that may be offset from the physiographic transition at the surface, using deep resistivity structure distinguish between modes of extensional upwelling and magmatism that may be vertically non-uniform, depth and magnitude of quasi-layered deep crustal low resistivity, particularly below West Antarctica, will be used to estimate crustal heat flux into the ice sheet base. | POLYGON((141.01732 -82.13,144.910279 -82.13,148.803238 -82.13,152.696197 -82.13,156.589156 -82.13,160.482115 -82.13,164.375074 -82.13,168.268033 -82.13,172.160992 -82.13,176.053951 -82.13,179.94691 -82.13,179.94691 -82.351835,179.94691 -82.57367,179.94691 -82.795505,179.94691 -83.01734,179.94691 -83.239175,179.94691 -83.46101,179.94691 -83.682845,179.94691 -83.90468,179.94691 -84.126515,179.94691 -84.34835,176.053951 -84.34835,172.160992 -84.34835,168.268033 -84.34835,164.375074 -84.34835,160.482115 -84.34835,156.589156 -84.34835,152.696197 -84.34835,148.803238 -84.34835,144.910279 -84.34835,141.01732 -84.34835,141.01732 -84.126515,141.01732 -83.90468,141.01732 -83.682845,141.01732 -83.46101,141.01732 -83.239175,141.01732 -83.01734,141.01732 -82.795505,141.01732 -82.57367,141.01732 -82.351835,141.01732 -82.13)) | POINT(160.482115 -83.239175) | false | false | ||||
Collaborative Research: Seismic Traverse of the Byrd Subglacial Basin-Field Test
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9222121 |
2002-01-01 | Bender, Michael; Dalziel, Ian W. |
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This award supports an in situ and short traverse seismic reflection/refraction and magnetotelluric experiment in West Antarctica. This collaborative experiment involves four awards at four institutions. The four-fold purpose is 1) to investigate part of the Byrd Subglacial Basin, 2) to test techniques for this work that could be done in a long traverse, 3) to determine the viability of the magnetotelluric method on a thick (electrically resistive) ice sheet, and 4) to evaluate the relative merits of refraction with wide reflection versus reflection with narrow refraction seismic studies in imaging the lithosphere. The geophysical techniques that will be employed are capable of imaging the ice sheet, the continental lithosphere, and the upper mantle, as well as determining physical properties of parts of the lithosphere and mantle. Investigations of outcrop geology over the last thirty years in West Antarctica and the Transantarctic Mountains have lead to recent interpretations that the crust is made up of many different lithospheric blocks. Seismic reflection work is the only way to image the crust in detail and the refraction work is the only way to determine physical properties of the layers and blocks defined by the reflection work. The magnetotelluric work is scientifically risky because it may not yield useful information when used over the electrically resistive ice sheet; however, if it works it has the potential to image molten rock in the crust and upper mantle. In a continental rift region such as West Antarctica, the presence of melt in the lithosphere is likely and, if documented, has very important ramifications to ice sheet dynamics. Research work supported by this award is expected to provide constraints to models of a range of crustal processes from models of ice sheet dynamics to tectonic and kinematic models of lithospheric thinning and rifting. | None | None | false | false |