[{"awards": "1918338 VanTongeren, Jill", "bounds_geometry": null, "date_created": "Tue, 18 Nov 2025 00:00:00 GMT", "description": "The ~ 182 Ma Dufek Intrusion of Antarctica, associated with the Ferrar Dolerite Province, is a large layered mafic intrusion that is estimated to be similar in size to the 8-9 km thick Bushveld Complex. Similar to the Bushveld Complex, the Dufek Intrusion displays a consistent stratigraphic progression of fractional crystallization all the way to the roof of the intrusion and contact with overlying granophyre. In this study, we test competing hypotheses for the \u0027big tank\u0027 vs. \u0027out-of-sequence emplacement\u0027 models for layered intrusions by presenting high precision CA-ID-TIMS zircon U-Pb ages, zircon \u03b5Hf, and zircon trace element compositions of 10 samples throughout the Dufek Intrusion stratigraphy. Our results suggest that the majority of zircon found in layered mafic intrusions is crystallized from the interstitial melt within the cumulate mush pile and cannot record the high temperature crystallization of the original magma. Cooling durations to the 800\u00b0C isotherm recorded by the zircons are consistent with 1D thermal modeling of conductive cooling of a single 6-7 km thick magma chamber emplaced in the shallow crust, rather than two separate intrusions as previously proposed. We suggest that there is little to no missing stratigraphy separating the outcrops in the Forrestal Range and Dufek Massif in the Dufek Intrusion, but the two exposures are instead separated by a fault buried beneath the Sallee Snowfield. Our conclusion is consistent with available geochronology, geochemistry and geophysical observations in the region.", "east": null, "geometry": null, "keywords": "Antarctica; Cryosphere; Ferrar Magmatic Province; Geochronology; Zircon", "locations": "Ferrar Magmatic Province; Antarctica", "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "VanTongeren, Jill", "project_titles": "The Dufek Intrusion Ages: Crystallization or Cooling?", "projects": [{"proj_uid": "p0010505", "repository": "USAP-DC", "title": "The Dufek Intrusion Ages: Crystallization or Cooling?"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Zircon geochronology constraints on the geometry and solidification timescales of the Dufek layered mafic intrusion, Antarctica", "uid": "601997", "west": null}, {"awards": "1543313 VanTongeren, Jill", "bounds_geometry": ["POLYGON((-55 -82,-54.5 -82,-54 -82,-53.5 -82,-53 -82,-52.5 -82,-52 -82,-51.5 -82,-51 -82,-50.5 -82,-50 -82,-50 -82.2,-50 -82.4,-50 -82.6,-50 -82.8,-50 -83,-50 -83.2,-50 -83.4,-50 -83.6,-50 -83.8,-50 -84,-50.5 -84,-51 -84,-51.5 -84,-52 -84,-52.5 -84,-53 -84,-53.5 -84,-54 -84,-54.5 -84,-55 -84,-55 -83.8,-55 -83.6,-55 -83.4,-55 -83.2,-55 -83,-55 -82.8,-55 -82.6,-55 -82.4,-55 -82.2,-55 -82))"], "date_created": "Mon, 29 Oct 2018 00:00:00 GMT", "description": "The dataset contains preliminary CA-ID-TIMS U-Pb zircon ages for 4 samples from the Dufek Intrusion, as well as major element mineral compositions for samples throughout the stratigraphy.", "east": -50.0, "geometry": ["POINT(-52.5 -83)"], "keywords": "Antarctica; Chemical Composition; Chemistry:rock; Chemistry:Rock; Crystallization; Dufek Complex; Geochemistry; Magma Chamber Procesess; Mass Spectrometry; Rocks; Snow/ice; Snow/Ice; Solid Earth; TIMS; Volcanic Deposits", "locations": "Antarctica", "north": -82.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "VanTongeren, Jill", "project_titles": "Collaborative Research: Testing the Hypothesis that Bigger Magma Chambers Crystallize Faster", "projects": [{"proj_uid": "p0000135", "repository": "USAP-DC", "title": "Collaborative Research: Testing the Hypothesis that Bigger Magma Chambers Crystallize Faster"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.0, "title": "U-Pb ages and mineral compositions from Dufek Intrusion", "uid": "601132", "west": -55.0}, {"awards": "0536526 Le Masurier, Wesley", "bounds_geometry": ["POLYGON((-136 -73,-133.4 -73,-130.8 -73,-128.2 -73,-125.6 -73,-123 -73,-120.4 -73,-117.8 -73,-115.2 -73,-112.6 -73,-110 -73,-110 -73.425,-110 -73.85,-110 -74.275,-110 -74.7,-110 -75.125,-110 -75.55,-110 -75.975,-110 -76.4,-110 -76.825,-110 -77.25,-112.6 -77.25,-115.2 -77.25,-117.8 -77.25,-120.4 -77.25,-123 -77.25,-125.6 -77.25,-128.2 -77.25,-130.8 -77.25,-133.4 -77.25,-136 -77.25,-136 -76.825,-136 -76.4,-136 -75.975,-136 -75.55,-136 -75.125,-136 -74.7,-136 -74.275,-136 -73.85,-136 -73.425,-136 -73))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This project uses geochemical studies to determine the origin of volcanic rocks from Marie Byrd Land (MBL), Antarctica. Surprisingly, adjacent volcanoes in the MBL have dramatically different compositions, ranging from phonolite to trachyte to rhyolite. This diversity offers an opportunity to constrain the processes responsible for generating silica oversaturated and undersaturated magmas in a single geologic setting. Previous work suggests that the most obvious and simplest explanation--crustal contamination--is not a significant factor, and that polybaric fractional crystallization is the major cause. This study evaluates these factors through analyses and interpretation of trace and rare earth element abundances, as well as Sr and Nd isotopic ratios. The broader impacts include outreach programs to the Girl Scouts of America, and dissemination of results through publications and meetings.", "east": -110.0, "geometry": ["POINT(-123 -75.125)"], "keywords": "Antarctica; Chemistry:rock; Chemistry:Rock; Geochemistry; Intracontinental Magmatism; IntraContinental Magmatism; Marie Byrd Land; Solid Earth", "locations": "Antarctica; Marie Byrd Land", "north": -73.0, "nsf_funding_programs": null, "persons": "Le Masurier, Wesley", "project_titles": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica", "projects": [{"proj_uid": "p0000534", "repository": "USAP-DC", "title": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.25, "title": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica", "uid": "600051", "west": -136.0}]

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Dataset Title/Abstract/Map	NSF Award(s)	Date Created	PIs / Scientists	Project Links	Abstract	Bounds Geometry	Geometry	Selected	Visible
Zircon geochronology constraints on the geometry and solidification timescales of the Dufek layered mafic intrusion, Antarctica	1918338	2025-11-18	VanTongeren, Jill	The Dufek Intrusion Ages: Crystallization or Cooling?	The ~ 182 Ma Dufek Intrusion of Antarctica, associated with the Ferrar Dolerite Province, is a large layered mafic intrusion that is estimated to be similar in size to the 8-9 km thick Bushveld Complex. Similar to the Bushveld Complex, the Dufek Intrusion displays a consistent stratigraphic progression of fractional crystallization all the way to the roof of the intrusion and contact with overlying granophyre. In this study, we test competing hypotheses for the 'big tank' vs. 'out-of-sequence emplacement' models for layered intrusions by presenting high precision CA-ID-TIMS zircon U-Pb ages, zircon εHf, and zircon trace element compositions of 10 samples throughout the Dufek Intrusion stratigraphy. Our results suggest that the majority of zircon found in layered mafic intrusions is crystallized from the interstitial melt within the cumulate mush pile and cannot record the high temperature crystallization of the original magma. Cooling durations to the 800°C isotherm recorded by the zircons are consistent with 1D thermal modeling of conductive cooling of a single 6-7 km thick magma chamber emplaced in the shallow crust, rather than two separate intrusions as previously proposed. We suggest that there is little to no missing stratigraphy separating the outcrops in the Forrestal Range and Dufek Massif in the Dufek Intrusion, but the two exposures are instead separated by a fault buried beneath the Sallee Snowfield. Our conclusion is consistent with available geochronology, geochemistry and geophysical observations in the region.	[]	[]	false	false
U-Pb ages and mineral compositions from Dufek Intrusion	1543313	2018-10-29	VanTongeren, Jill	Collaborative Research: Testing the Hypothesis that Bigger Magma Chambers Crystallize Faster	The dataset contains preliminary CA-ID-TIMS U-Pb zircon ages for 4 samples from the Dufek Intrusion, as well as major element mineral compositions for samples throughout the stratigraphy.	["POLYGON((-55 -82,-54.5 -82,-54 -82,-53.5 -82,-53 -82,-52.5 -82,-52 -82,-51.5 -82,-51 -82,-50.5 -82,-50 -82,-50 -82.2,-50 -82.4,-50 -82.6,-50 -82.8,-50 -83,-50 -83.2,-50 -83.4,-50 -83.6,-50 -83.8,-50 -84,-50.5 -84,-51 -84,-51.5 -84,-52 -84,-52.5 -84,-53 -84,-53.5 -84,-54 -84,-54.5 -84,-55 -84,-55 -83.8,-55 -83.6,-55 -83.4,-55 -83.2,-55 -83,-55 -82.8,-55 -82.6,-55 -82.4,-55 -82.2,-55 -82))"]	["POINT(-52.5 -83)"]	false	false
Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica	0536526	2009-01-01	Le Masurier, Wesley	Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica	This project uses geochemical studies to determine the origin of volcanic rocks from Marie Byrd Land (MBL), Antarctica. Surprisingly, adjacent volcanoes in the MBL have dramatically different compositions, ranging from phonolite to trachyte to rhyolite. This diversity offers an opportunity to constrain the processes responsible for generating silica oversaturated and undersaturated magmas in a single geologic setting. Previous work suggests that the most obvious and simplest explanation--crustal contamination--is not a significant factor, and that polybaric fractional crystallization is the major cause. This study evaluates these factors through analyses and interpretation of trace and rare earth element abundances, as well as Sr and Nd isotopic ratios. The broader impacts include outreach programs to the Girl Scouts of America, and dissemination of results through publications and meetings.	["POLYGON((-136 -73,-133.4 -73,-130.8 -73,-128.2 -73,-125.6 -73,-123 -73,-120.4 -73,-117.8 -73,-115.2 -73,-112.6 -73,-110 -73,-110 -73.425,-110 -73.85,-110 -74.275,-110 -74.7,-110 -75.125,-110 -75.55,-110 -75.975,-110 -76.4,-110 -76.825,-110 -77.25,-112.6 -77.25,-115.2 -77.25,-117.8 -77.25,-120.4 -77.25,-123 -77.25,-125.6 -77.25,-128.2 -77.25,-130.8 -77.25,-133.4 -77.25,-136 -77.25,-136 -76.825,-136 -76.4,-136 -75.975,-136 -75.55,-136 -75.125,-136 -74.7,-136 -74.275,-136 -73.85,-136 -73.425,-136 -73))"]	["POINT(-123 -75.125)"]	false	false

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