Lithologic and geochemical comparison of supracrustal assemblages in the granulite- and amphibolite-facies terrains of southern India

Conference · Mon Dec 31 23:00:00 EST 1984 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6646709

Chacko, T; Rogers, J J.W.; Ravindrakumar, G R

Lithologic and geochemical comparisons show that supracrustal assemblages in the amphibolite- and granulite-facies terrains of southern India formed in different tectonic settings and had different sediment sources. In terrains of amphibolite-facies gneisses, older greenstone belts are composed mainly of ultramafic and mafic volcanic rocks and pelitic sediments; younger belts, mostly in greenschist facies, contain mafic and felsic volcanic rocks and sedimentary suites consisting of graywackes, quartzites, and other clastic rocks. In contrast, supracrustal rocks of the granulite terrain, referred to as the khondalite suite, consist of pelitic an semi-pelitic metasedimentary rocks with lesser amounts of calc-granulites and quartzites; the only igneous rocks are minor, concordant mafic granulites. The preceding differences suggest that the greenstones formed in tectonically active basins, whereas the khondalite suite developed in a stable, platformal environment. Thus, supracrustal rocks of the granulite terrain are not deeply eroded roots of greenstone belts but formed in a different tectonic environment with a relatively sialic source of sediment. The worldwide association of platformal sedimentary rocks with granulite-facies terrains suggests that a stable, presumably thick, continental crust is a prerequisite for extensive granulite-facies metamorphism.

• Research Organization: Univ. of North Carolina, Chapel Hill (USA)
• OSTI ID: 6646709
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
580400 -- Geochemistry-- (-1989)
AMPHIBOLITES
ASIA
CHEMISTRY
COMPARATIVE EVALUATIONS
CONTINENTAL CRUST
DEVELOPING COUNTRIES
EARTH CRUST
GEOCHEMISTRY
GEOLOGIC HISTORY
GRANULITES
INDIA
LITHOLOGY
METAMORPHIC ROCKS
METAMORPHISM
PETROGENESIS
ROCKS
TECTONICS