Journal
JOURNAL OF ASIAN EARTH SCIENCES
Volume 35, Issue 3-4, Pages 273-284Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jseaes.2008.12.008
Keywords
UHP; North Tibet; Orthogneiss; Pseudosection; Eclogite; North Qaidam
Categories
Ask authors/readers for more resources
Many UHP terranes contain abundant felsic gneiss with volumetrically minor mafic and ultramafic blocks. The mafic rocks typically preserve the high-pressure assemblages, whereas felsic gneisses preserve low pressure mineral assemblages. In the absence coesite it can be difficult to confirm that felsic lithologies experienced high-pressure conditions. This has lead to uncertainty over the regional extent of UHP terranes. We conducted a detailed study of textures, mineral parageneses and compositions of a suite of eclogite-bearing orthogneisses in the Luliang Shan from the North Qaidam UHP metamorphic belt. Two distinctive gneisses were observed: volumetrically dominant, uniform leucocratic orthogneiss and mica-rich gneiss which occurs only in proximity to eclogite blocks. Two pseudosections have been constructed to constrain the P-T conditions recorded by the mineral assemblages and mineral zoning observed in the orthogneiss. Relic high-pressure inclusions and predicted conditions of garnet growth suggest that the orthogneiss followed a metamorphic P-T path comparable to the eclogite it encloses, with peak pressure at similar to 26 kbar very close to the quartz-coesite phase boundary. (C) 2009 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available