A STAUROLITE-BEARING CORUNDUM-GARNET GNEISS FROM THE EASTERN SØR RONDANE MOUNTAINS, ANTARCTICA

Staurolite is found as inclusions in garnet in a corundum-garnet gneiss from an outcrop of two-pyroxene gneiss in the eastern Sør Rondane Mountains. The staurolite is a zinc-poor variety of normal iron content (ZnO=0.10-0.32wt%; X_<Fe>=0.74-0.80), and occurs only in 'domains', consis...

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Bibliographic Details
Main Authors: Masao ASAMI, Edward S. GREW, Hiroshi MAKIMOTO
Format: Report
Language:English
Published: Department of Geological Sciences, College of Liberal Arts, Okayama University 1990
Subjects:
Sør-Rondane
Sør Rondane Mountains
Antarc*
Antarctica
Online Access:https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2618
http://id.nii.ac.jp/1291/00002618/
https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2618&item_no=1&attribute_id=18&file_no=1
Description
Summary:Staurolite is found as inclusions in garnet in a corundum-garnet gneiss from an outcrop of two-pyroxene gneiss in the eastern Sør Rondane Mountains. The staurolite is a zinc-poor variety of normal iron content (ZnO=0.10-0.32wt%; X_<Fe>=0.74-0.80), and occurs only in 'domains', consisting mainly of plagioclase, enclosed in the zoned garnet with magnesian cores (X_<Fe>=0.69-0.70). From textural and mineralogical observations, it is possible to distinguish (1) a staurolite-bearing mineral association in the domains and (2) a granulite-facies association of the garnet core with the matrix constituents plagioclase, biotite, sillimanite, corundum. spinel, magnetite and ilmenite. In addition, compositional relations between staurolite and the association garnet-corundum-spinel-sillimanite is consistent with the prograde reaction staurolite=garnet+corundum+spinel+sillimanite+H_2O. On the basis of textural features and paragenetic relations, staurolite in this gneiss is interpreted to be a relic that was isolated from the matrix by growing of garnet in a prograde metamorphic process attaining the granulite facies. A later, probably amphibolite-facies metamorphic episode is suggested by Fe-Mg redistribution between garnet and biotite in direct contact.

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