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Proterozoic metamorphism and uplift history of the north-central Laramie Mountains, Wyoming, USA

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Title Proterozoic metamorphism and uplift history of the north-central Laramie Mountains, Wyoming, USA
 
Creator PATEL, SC
FROST, BR
CHAMBERLAIN, KR
SNYDER, GL
 
Subject p-t paths
anorthosite complex
crustal extension
new-hampshire
shear zone
sapphirine
rocks
thermobarometry
granulites
cordierite
 
Description The Laramie Mountains of south-eastern Wyoming contain two metamorphic domains that are separated by the 1.76 Ga. Laramie Peak shear zone (LPSZ). South of the LPSZ lies the Palmer Canyon block, where apatite U-Pb ages are c. 1745 Ma and the rocks have undergone Proterozoic kyanite-grade Barrovian metamorphism. In contrast, in the Laramie Peak block, north of the shear zone, the U-Pb apatite ages are 2.4-2.1 Ga, the granitic rocks are unmetamorphosed and supracrustal rocks record only low-T amphibolite facies metamorphism that is Archean in age. Peak mineral assemblages in the Palmer Canyon block include (a) quartz-biotite-plagioclase-garnet-staurolite-kyanite in the pelitic schists; (b) quartz-biotite-plagioclase-low-Ca amphiboles-kyanite in Mg-Al-rich schists, and locally (c) hornblende-plagioclase-garnet in amphibolites. All rock types show abundant textural evidence of decompression and retrograde re-equilibration. Notable among the texturally late minerals are cordierite and sapphirine, which occur in coronas around kyanite in Mg-Al-rich schists. Thermobarometry from texturally early and late assemblages for samples from different areas within the Palmer Canyon block define decompression from >7 kbar to
 
Publisher BLACKWELL SCIENCE INC
 
Date 2011-07-19T05:54:07Z
2011-12-26T12:51:02Z
2011-12-27T05:37:20Z
2011-07-19T05:54:07Z
2011-12-26T12:51:02Z
2011-12-27T05:37:20Z
1999
 
Type Article
 
Identifier JOURNAL OF METAMORPHIC GEOLOGY, 17(3), 243-258
0263-4929
http://dspace.library.iitb.ac.in/xmlui/handle/10054/5191
http://hdl.handle.net/10054/5191
 
Language en