Geochemistry of high-grade supracrustal rocks from the Kerala Khondalite Belt and adjacent massif charnockites, South India

Chacko, Thomas; Kumar, G. R. Ravindra; Meen, James K.; Rogers, John J. W.

doi:10.1016/0301-9268(92)90040-u

Cited by 92 publications

(42 citation statements)

References 36 publications

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“…The Ponmudi Unit became well known as one of the type localities for in-situ charnockitization of garnet-biotite gneisses and the breakdown of charnockites (Ravindra Kumar and Chacko 1986;Santosh and Yoshida 1986;Hansen et al 1987;Jackson et al 1988;Santosh et al 1990;Raith and Srikantappa 1993;Harley and Santosh 1995). Based on geochemical criteria, Chacko et al (1992) classified the rocks of the Ponmudi Unit as entirely supracrustal and suggested that the precursor sediments most likely were derived from the Cardamom Hills north of the KKB (Fig. 1).…”

Section: Geological Settingmentioning

confidence: 97%

“…Based on geochemical investigations, Chacko et al (1992) concluded that the KKB represents a large supracrustal unit of predominantly high-grade metamorphic rocks, which were derived from sedimentary or volcanic protoliths. Geochronological studies have shown that the metamorphic history is closely related to the Pan-African orogeny and that peak-metamorphism occurred ca.…”

Section: Introductionmentioning

confidence: 99%

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Monazite dating of granitic gneisses and leucogranites from the Kerala Khondalite Belt, southern India: implications for Late Proterozoic crustal evolution in East Gondwana

Braun

Bröcker

2004

International Journal of Earth Sciences

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Two stages of granitic magmatism occurred during the Pan-African evolution of the Kerala Khondalite Belt (KKB) in southern India. Granitic gneisses were derived from porphyritic granites, which intruded prior to the main stage of deformation and peakmetamorphism. Subsequently, leucogranites and leucotonalites formed during fluid-absent melting and intruded the gneiss sequences. Monazites from granitic gneisses, leucogranites and a leucotonalite were investigated by conventional U-Pb and electron microprobe dating in order to distinguish the different stages of magma emplacement. U-Pb monazite dating yielded a wide range of ages between 590-520 Ma which are interpreted to date high-grade metamorphism rather than magma emplacement. The results of this study indicate that the KKB experienced protracted heating (>50 Ma) at temperatures above 750-800 C during the Pan-African orogeny. The tectonometamorphic evolution of the study area is comparable to southern Madagascar which underwent a similar sequence of events earlier than the KKB. The results of this study further substantiate previous assertions that the timing of high-grade metamorphism in East Gondwana shifted from west to east during the Late Proterozoic.

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Section: Geological Settingmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Monazite dating of granitic gneisses and leucogranites from the Kerala Khondalite Belt, southern India: implications for Late Proterozoic crustal evolution in East Gondwana

Braun

Bröcker

2004

International Journal of Earth Sciences

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“…1). The area is underlain by Precambrian rocks, mainly biotite gneisses and charnockites (Krishnan, 1982;Chacko et al, 1992). Charnockite is a rock formed by injection from the depth of metamorphic fluids and is characterized by a prominent content of orthopyroxene (Newton, 1992).…”

Section: Geology Soils and Climatementioning

confidence: 99%

Origin of sulphur in soil and water in a Precambrian terrain, S. India.

et al. 1994

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“…The minor differences in the Na 2 O and K 2 O values are probably due to high-grade metamorphism. Variations in mobile Na 2 O and K 2 O values are also encountered in other belts of the earth's crust that have undergone high-grade metamorphism at granulite-facies conditions (Chacko et al 1992). In the FeO+MgO vs K 2 O/K 2 O+Na 2 O diagram, most specimens fall into the litharenite field, and some into a 12 198.09 198.73 197.60 197.42 199.21 Ba -----413 413 542 713 728.00 N b ---------113.20 Zr -----282 243 299 243 144.60 Y -----137 129 133 133 122.00 Sr -----262 299 245 245 198.40 R b --------101.90 field transitional from litharenite to arkose.…”

Section: Odemis -Kiraz Submassifmentioning

confidence: 97%

Revision of "Leptite-gneisses" in the Menderes Massif: a supracrustal metasedimentary origin

Dora

Candan

Kaya

et al. 2001

International Journal of Earth Sciences

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The Pan-African basement of the Menderes Massif comprises a regular lithological succession that reaches a thickness of 8 km, the oldest units of which are, in ascending order, so-called leptite-gneisses, a quartzite-sequence transition zone and mica schists. New findings suggest that the protoliths for the leptite-gneisses, proposed to be of volcanic origin in previous studies, were predominantly clastic sediments of litharenitic composition. Geochemical data indicate that the protoliths for the leptite-gneisses were of cratonic provenance. Because they have undergone PanAfrican polymetamorphism and are intruded by approximately 550 Ma gneisses of granitic origin, it is believed that the time of deposition of their protoliths was Late Proterozoic. Relict parageneses indicate that the Pan-African metamorphism reached granulite-facies conditions in the leptite-gneisses. Supracrustal sedimentary origin of these rocks require that these rocks, formerly termed leptite and/or leptite-gneiss, should be renamed sillimanite±garnet gneiss and/or paragneiss.

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Geochemistry of high-grade supracrustal rocks from the Kerala Khondalite Belt and adjacent massif charnockites, South India

Cited by 92 publications

References 36 publications

Monazite dating of granitic gneisses and leucogranites from the Kerala Khondalite Belt, southern India: implications for Late Proterozoic crustal evolution in East Gondwana

Monazite dating of granitic gneisses and leucogranites from the Kerala Khondalite Belt, southern India: implications for Late Proterozoic crustal evolution in East Gondwana

Origin of sulphur in soil and water in a Precambrian terrain, S. India.

Revision of "Leptite-gneisses" in the Menderes Massif: a supracrustal metasedimentary origin

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