Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?
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 s...
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ftmaineuniv:oai:digitalcommons.library.umaine.edu:orsp_reports-1161 2023-05-15T14:00:37+02:00 Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? Grew, Edward S. 2009-12-16T08:00:00Z application/pdf https://digitalcommons.library.umaine.edu/orsp_reports/151 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1161&context=orsp_reports unknown DigitalCommons@UMaine https://digitalcommons.library.umaine.edu/orsp_reports/151 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1161&context=orsp_reports This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). University of Maine Office of Research Administration: Grant Reports Antarctic Glaciology and Geophysics Geophysics and Seismology Glaciology text 2009 ftmaineuniv 2023-03-12T19:15:42Z 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. The working hypothesis is that high ... Text Antarc* Antarctic Antarctica Prydz Bay The University of Maine: DigitalCommons@UMaine Antarctic The Antarctic Prydz Bay Larsemann Hills ENVELOPE(76.217,76.217,-69.400,-69.400) |
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Open Polar |
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The University of Maine: DigitalCommons@UMaine |
op_collection_id |
ftmaineuniv |
language |
unknown |
topic |
Antarctic Glaciology and Geophysics Geophysics and Seismology Glaciology |
spellingShingle |
Antarctic Glaciology and Geophysics Geophysics and Seismology Glaciology Grew, Edward S. Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
topic_facet |
Antarctic Glaciology and Geophysics Geophysics and Seismology Glaciology |
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. The working hypothesis is that high ... |
format |
Text |
author |
Grew, Edward S. |
author_facet |
Grew, Edward S. |
author_sort |
Grew, Edward S. |
title |
Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
title_short |
Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
title_full |
Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
title_fullStr |
Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
title_full_unstemmed |
Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
title_sort |
boron in antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust? |
publisher |
DigitalCommons@UMaine |
publishDate |
2009 |
url |
https://digitalcommons.library.umaine.edu/orsp_reports/151 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1161&context=orsp_reports |
long_lat |
ENVELOPE(76.217,76.217,-69.400,-69.400) |
geographic |
Antarctic The Antarctic Prydz Bay Larsemann Hills |
geographic_facet |
Antarctic The Antarctic Prydz Bay Larsemann Hills |
genre |
Antarc* Antarctic Antarctica Prydz Bay |
genre_facet |
Antarc* Antarctic Antarctica Prydz Bay |
op_source |
University of Maine Office of Research Administration: Grant Reports |
op_relation |
https://digitalcommons.library.umaine.edu/orsp_reports/151 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1161&context=orsp_reports |
op_rights |
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). |
_version_ |
1766269849204424704 |