Differentiation of Late Archean Crust in the Eastern Dharwar Craton, Krishnagiri-Salem Area, South India
| Autor: | R. C. Newton, Sheila Lindenberg, E. C. Hansen, A. S. Janardhar |
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| Rok vydání: | 1995 |
| Předmět: | |
| Zdroj: | The Journal of Geology. 103:629-651 |
| ISSN: | 1537-5269 0022-1376 |
| Popis: | The Late Archean crust south of Krishnagiri, Tamil Nadu, consists of tonalitic-trondhjemitic-granodioritic (TTG) gneisses with mafic and sedimentary enclaves, formed between 2.7 and 2.5 Ga and metamorphosed at amphibolite facies in the north to granulite facies in the south close to 2.5 Ga. Migmatization occurred at all grades, and numerous small granite bodies were emplaced near the amphibolite-to-granulite facies horizon. This nearly syn-accretion meta-morphism affected the entire crust and left a chemically differentiated section later exposed by uplift and erosion. Detailed chemical and petrographic study of >60 samples across a 90 km traverse provides evidence for an essentially unbroken crustal cross-section: Paleopressures range from 4 kbar (corresponding to 12-14 km paleodepth) in the north to 8 kbar (corresponding to 24-28 km paleodepth) to the south. Corresponding paleotemperatures vary between 650° and 800°C across the section. Mineralogic grade monitors, particularly increasing $TiO_{2}$ conte... |
| Databáze: | OpenAIRE |
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