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The Proterozoic P-T-t Evolution of the Kemp Land Coast, East Antarctica; Constraints from Si-saturated and Si-undersaturated Metapelites
Citation
Halpin, JA and White, RW and Clarke, GL and Kelsey, DE, The Proterozoic P-T-t Evolution of the Kemp Land Coast, East Antarctica; Constraints from Si-saturated and Si-undersaturated Metapelites, Journal of Petrology, 48, (7) pp. 1321-1349. ISSN 0022-3530 (2007) [Refereed Article]
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Copyright Statement
Copyright 2007 Oxford University Press
DOI: doi:10.1093/petrology/egm020
Abstract
Integrated metamorphic and geochronological data place new constraints on the metamorphic evolution of a Neoproterozoic orogen in east Antarctica. Granulite-facies rocks from a 150km stretch of the Kemp Land coast reflect peak conditions involving T ≈ 870-990°C at P ≈ 74-10 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. 940Ma Rayner Orogeny. Complex compositional zoning in monazite suggests high-T recrystallization over c 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. © The Author 2007. Published by Oxford University Press. All rights reserved.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | electron microprobe monazite dating; granulite facies; Rayner Complex; sapphirine;THERMOCALC |
| Research Division: | Earth Sciences |
| Research Group: | Geology |
| Research Field: | Igneous and metamorphic petrology |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the earth sciences |
| UTAS Author: | Halpin, JA (Dr Jacqueline Halpin) |
| ID Code: | 75907 |
| Year Published: | 2007 |
| Web of Science® Times Cited: | 45 |
| Deposited By: | Centre for Ore Deposit Research - CODES CoE |
| Deposited On: | 2012-02-20 |
| Last Modified: | 2012-06-27 |
| Downloads: | 0 |
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