The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites
Copyright © The Author 2007. Published by Oxford University Press. All rights reserved. Integrated metamorphic and geochronological data place new constraints on the metamorphic evolution of a Neoproterozoic orogen in east Antarctica. Granulite-facies rocks from a 150 km stretch of the Kemp Land coa...
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Online Access: | http://hdl.handle.net/2440/43366 https://doi.org/10.1093/petrology/egm020 |
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/43366 2023-12-24T10:11:21+01:00 The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites Halpin, J. White, R. Clarke, G. Kelsey, D. 2007 http://hdl.handle.net/2440/43366 https://doi.org/10.1093/petrology/egm020 en eng Oxford Univ Press Journal of Petrology, 2007; 48(7):1321-1349 0022-3530 1460-2415 http://hdl.handle.net/2440/43366 doi:10.1093/petrology/egm020 http://dx.doi.org/10.1093/petrology/egm020 electron microprobe monazite dating granulite facies Rayner Complex sapphirine thermocalc Journal article 2007 ftunivadelaidedl https://doi.org/10.1093/petrology/egm020 2023-11-27T23:19:48Z Copyright © The Author 2007. Published by Oxford University Press. All rights reserved. Integrated metamorphic and geochronological data place new constraints on the metamorphic evolution of a Neoproterozoic orogen in east Antarctica. Granulite-facies rocks from a 150 km stretch of the Kemp Land coast reflect peak conditions involving T 870–990°C at P 7·4–10 kbar, with pressure increasing westward towards an Archaean craton. Electron microprobe-derived (Th + U)–Pb monazite ages from metapelitic assemblages indicate that the major mineral textures in these rocks developed during the c. 940 Ma Rayner Orogeny. Complex compositional zoning in monazite suggests high-T recrystallization over c. 25 Myr. Diversity in metapelitic reaction textures reflects silica and ferromagnesian content: Si-saturated Fe-rich metapelites contain garnet that is partially pseudomorphed by biotite and sillimanite, whereas Si-saturated Mg-rich metapelites and Si-undersaturated metapelitic pods have reaction microstructures involving cordierite enclosing orthopyroxene, garnet and/or sapphirine, cordierite + sapphirine symplectites around sillimanite and coarse-grained orthopyroxene + corundum separated by sapphirine coronae. Interpretations based on P–T pseudosections provide integrated bulk-rock constraints and indicate a clockwise P–T–t path characterized by a post-peak P–T trajectory with dP/dT 15–20 bar/ °C. This moderately sloped decompressive-cooling P–T path is in contrast to near-isothermal decompression P–T paths commonly cited for this region of the Rayner Complex, with implications for the post-collisional tectonic response of the mid- to lower crust within this orogenic belt. J. A. Halpin, R. W. White, G. L. Clarke and D. E. Kelsey Article in Journal/Newspaper Antarc* Antarctica East Antarctica Kemp Land The University of Adelaide: Digital Library East Antarctica Rayner ENVELOPE(-45.166,-45.166,-60.650,-60.650) Kemp Land ENVELOPE(57.500,57.500,-67.500,-67.500) Kelsey ENVELOPE(-22.306,-22.306,-80.448,-80.448) Journal of Petrology 48 7 1321 1349 |
institution |
Open Polar |
collection |
The University of Adelaide: Digital Library |
op_collection_id |
ftunivadelaidedl |
language |
English |
topic |
electron microprobe monazite dating granulite facies Rayner Complex sapphirine thermocalc |
spellingShingle |
electron microprobe monazite dating granulite facies Rayner Complex sapphirine thermocalc Halpin, J. White, R. Clarke, G. Kelsey, D. The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
topic_facet |
electron microprobe monazite dating granulite facies Rayner Complex sapphirine thermocalc |
description |
Copyright © The Author 2007. Published by Oxford University Press. All rights reserved. Integrated metamorphic and geochronological data place new constraints on the metamorphic evolution of a Neoproterozoic orogen in east Antarctica. Granulite-facies rocks from a 150 km stretch of the Kemp Land coast reflect peak conditions involving T 870–990°C at P 7·4–10 kbar, with pressure increasing westward towards an Archaean craton. Electron microprobe-derived (Th + U)–Pb monazite ages from metapelitic assemblages indicate that the major mineral textures in these rocks developed during the c. 940 Ma Rayner Orogeny. Complex compositional zoning in monazite suggests high-T recrystallization over c. 25 Myr. Diversity in metapelitic reaction textures reflects silica and ferromagnesian content: Si-saturated Fe-rich metapelites contain garnet that is partially pseudomorphed by biotite and sillimanite, whereas Si-saturated Mg-rich metapelites and Si-undersaturated metapelitic pods have reaction microstructures involving cordierite enclosing orthopyroxene, garnet and/or sapphirine, cordierite + sapphirine symplectites around sillimanite and coarse-grained orthopyroxene + corundum separated by sapphirine coronae. Interpretations based on P–T pseudosections provide integrated bulk-rock constraints and indicate a clockwise P–T–t path characterized by a post-peak P–T trajectory with dP/dT 15–20 bar/ °C. This moderately sloped decompressive-cooling P–T path is in contrast to near-isothermal decompression P–T paths commonly cited for this region of the Rayner Complex, with implications for the post-collisional tectonic response of the mid- to lower crust within this orogenic belt. J. A. Halpin, R. W. White, G. L. Clarke and D. E. Kelsey |
format |
Article in Journal/Newspaper |
author |
Halpin, J. White, R. Clarke, G. Kelsey, D. |
author_facet |
Halpin, J. White, R. Clarke, G. Kelsey, D. |
author_sort |
Halpin, J. |
title |
The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
title_short |
The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
title_full |
The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
title_fullStr |
The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
title_full_unstemmed |
The proterozoic P-T-t evolution of the Kemp Land coast, east Antarctica; Constraints from Si-saturated and Si-undersaturated metapelites |
title_sort |
proterozoic p-t-t evolution of the kemp land coast, east antarctica; constraints from si-saturated and si-undersaturated metapelites |
publisher |
Oxford Univ Press |
publishDate |
2007 |
url |
http://hdl.handle.net/2440/43366 https://doi.org/10.1093/petrology/egm020 |
long_lat |
ENVELOPE(-45.166,-45.166,-60.650,-60.650) ENVELOPE(57.500,57.500,-67.500,-67.500) ENVELOPE(-22.306,-22.306,-80.448,-80.448) |
geographic |
East Antarctica Rayner Kemp Land Kelsey |
geographic_facet |
East Antarctica Rayner Kemp Land Kelsey |
genre |
Antarc* Antarctica East Antarctica Kemp Land |
genre_facet |
Antarc* Antarctica East Antarctica Kemp Land |
op_source |
http://dx.doi.org/10.1093/petrology/egm020 |
op_relation |
Journal of Petrology, 2007; 48(7):1321-1349 0022-3530 1460-2415 http://hdl.handle.net/2440/43366 doi:10.1093/petrology/egm020 |
op_doi |
https://doi.org/10.1093/petrology/egm020 |
container_title |
Journal of Petrology |
container_volume |
48 |
container_issue |
7 |
container_start_page |
1321 |
op_container_end_page |
1349 |
_version_ |
1786163759139520512 |