Low-pressure granulites from the Ketilidian mobile belt of southern Greenland

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Authors:Dempster, T. J.; Harrison, T. N.; Brown, P. E.; Hutton, D. H. W.
Author Affiliations:Primary:
SURRC, Isot. Geol. Unit, Glasgow, United Kingdom
Univ. Aberdeen, United Kingdom
Univ. St. Andrews, United Kingdom
Univ. Durham, United Kingdom
Volume Title:Journal of Petrology
Source:Journal of Petrology, 32(5), p.979-1004. Publisher: Clarendon Press, Oxford, United Kingdom. ISSN: 0022-3530
Publication Date:1991
Note:In English. 66 refs.; illus. incl. 3 tables, geol. sketch map
Summary:Early Proterozoic cordierite-garnet-orthopyroxene-K-feldspar meta- sedimentary gneisses occur in the flat-lying complex of the S part of the Ketilidian mobile belt (1800-1700 m.y.), Greenland. These granulites contain low-P assemblages and are developed in both regional metamorphic rocks and in some thermal aureoles of contemporaneous rapakivi granite plutons. Thermobarometry shows that both the regional and contact metamorphism occurred at 2-4 kbar and 650-800 degrees C. The granulites were developed in an extensional tectonic regime, and apparently record the culmination of a single thermotectonic event. There is a close temporal association between the peak of high-grade metamorphism and the emplacement of synorogenic rapakivi granites, and melts from the meta-sedimentary pile probably contributed largely to the granites. The low P and high T for regional metamorphism require geothermal gradients > 60 degrees C/km, and are consistent with the presence of regional extensional tectonics, synorogenic magmatism and underplating of mafic magma in this area during the Ketilidian. [R.A.H.]
Subjects:Gneisses; Low pressure; Metamorphic rocks; Metasedimentary rocks; P-T conditions; Petrology; Pressure; Arctic region; Greenland; Ketilidian mobile belt; Southern Greenland
Abstract Numbers:92M/2281
Record ID:1991057471
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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