creators_name: Halpin, JA
creators_name: White, RW
creators_name: Clarke, GL
creators_name: Kelsey, DE
creators_id: jahalpin@utas.edu.au
creators_id: rwhite@uni-mainz.de
creators_id: geoffc@mail.usyd.edu.au
creators_id: david.kelsey@adelaide.edu.au
type: article
datestamp: 2008-05-26 02:37:43
lastmod: 2008-07-18 11:00:05
metadata_visibility: show
title: The Proterozoic P-T-t Evolution of the Kemp Land Coast, East Antarctica; Constraints from Si-saturated and Si-undersaturated Metapelites
ispublished: pub
subjects: 260100
full_text_status: restricted
keywords: electron microprobe monazite dating; granulite facies;
Rayner Complex; sapphirine; THERMOCALC
note: The definitive publisher-authenticated version is available online at: www.oxfordjournals.org
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 150 km stretch of the Kemp Land coast reflect peak conditions involving T~870-990 ºC 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 Siundersaturated 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/ºC. 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.
date: 2007-07
date_type: submitted
publication: Journal of Petrology
volume: 48
number: 7
pagerange: 1321-1349
id_number: 10.1093/petrology/egm020
refereed: TRUE
official_url: http://petrology.oxfordjournals.org/cgi/content/full/48/7/1321
citation: Halpin, JA and White, RW and Clarke, GL and Kelsey, DE (2007) 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.
document_url: http://eprints.utas.edu.au/6555/1/Halpin_et_al_2007.pdf