Progressive Metamorphism of Mafic Rocks from Greenschist to Granulite Facies in the Dharwar Craton of South India

Raase, P.; Raith, M.; Ackermand, D.; Lal, Radha Krishna

doi:10.1086/629027

Cited by 139 publications

(41 citation statements)

References 25 publications

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“…In this northern part of the craton, it is easier to distinguish the two sequences and unconformities between them have been identified (Venkata Dasu et al 1991). These unconformities separate the Sargur rocks and granite-gneiss terrains, which have undergone amphibolite facies regional metamorphism, from the overlying volcano sedimentary Dharwar successions which have undergone metamorphic transformation to a lesser degree (Raase et al 1986). Both of these supracrustal sequences have also been differentiated according to stratigraphic, lithological and structural criteria (Swami Nath & Ramakrishnan 1981, Chadwick et al 1981, Viswanatha et al 1982, Ramakrishnan & Viswanatha 1983, 1987).…”

Section: Sargurjdharwar Controversymentioning

confidence: 99%

“…As a whole, the Dharwar craton gives a representative picture of the continental crust at the end of the Archaean. Indeed, a variation in the grade of regional metamorphism is observed along a N-S axis from greenschist to granulite facies (Raase et al 1986). Pressures vary from 2-3 kbar in the north to 7-8 kbar in the south (Newton 1990).…”

Section: Geological Backgroundmentioning

confidence: 99%

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Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

Chardon

Cartigny

Jayananda

1996

Journal of Structural Geology

139

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Abstract-The Archaean Dharwar craton is characterized by two greenstone successions: the > 3 Ga Sargur Group and the 3.0-2.5 Ga Dharwar Supergroup. Examples of both successions are described from the region of Jayachamarajapura where they are also distinguished by different tectonic patterns. The younger greenstones have undergone only minor deformation and are only slightly metamorphosed and so provide a good case study of the relative behavior of greenstones in relation to their granite-gneiss country rocks. A detailed structural analysis indicates two strain fields associated with two deformational episodes: Dr and Dz. The Dr episode produced domeand-basin structures and affected merely the older greenstones and the gneisses. The mapped strain field is compatible with the hypothesis that it is associated with the development of diapiric-type gravitational instabilities. The Dz episode affects only the younger greenstone belt, which has the overall geometry of a complex syncline. It is discordant over a complex of gneisses and older greenstones that was deformed during the Dr episode. The base of the discordant cover sequence is tectonized and constitutes a dtcollement surface. Kinematic criteria at this surface have opposite sense and converge towards the belt axis. These structural features are interpreted in terms of progressive deformation compatible with the incipient development of a sagducting trough.These results are consistent with those obtained from other parts of the craton, where the tectonic evolution appears to reflect mainly relative vertical displacements facilitated by the reheating of continental crust during two major Archaean tectonometamorphic episodes.

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Section: Sargurjdharwar Controversymentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

Chardon

Cartigny

Jayananda

1996

Journal of Structural Geology

139

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“…This conclusion is based on a set of geological evidence, the most convincing being the progressive change of metamorphic grade, from granulite-facies rocks in the southern part of the craton, to greenschist-facies rocks in the north. P-T calculations, both in the Peninsular Gneisses (Janardhan et al, 1982;Hansen et al, 1984;Gopalakrishna et al, 1986;Stähle et al, 1987;Sen and Bhattacharya, 1990) and in the metapelites (Srinivasan and Tareen, 1972;Rollinson et al, 1981;Harris and Jayaram, 1982) or mafic rocks (Raase et al, 1986) of the greenstone belts allow quantification of the metamorphic gradient. P -T conditions span from nearly 8 Kb and 800 8C (granulite facies) at 128 latitude, to 3.5 Kb and 500 8C (greenschist facies) at 158N.…”

Section: A Crustal Cross-sectionmentioning

confidence: 99%

Syntectonic granite emplacement at different structural levels: the Closepet granite, South India

Moyen

Nédélec

Martin

et al. 2003

Journal of Structural Geology

113

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The Closepet granite, in South India, is a large (400 km long but only 30 km wide), elongate, Late Archaean granitic body. Structural levels from deep crust to upper levels crop out, as evidenced by a shallowing of paleo-depths from north to south all along the Closepet granite. This allows the study of the emplacement of the same granitic body at various crustal levels. Four zones have been identified: a root zone, where magmas are collected in active shear zones; a transfer zone, featuring large-scale magma ascent and crystal -liquid partitioning in the granitic 'mush'; a 'gap', where the mush was filtered, allowing only the liquids to rise; shallow intrusions, filled with this liquid.The Closepet granite was emplaced syntectonically. Field work and anisotropy of magnetic susceptibility allowed documentation of steep foliations with subhorizontal lineations, both in the root and transfer zones and in the shallow intrusions. Remote sensing evidenced a network of shear zones bounding the Closepet granite. In the porphyritic root and transfer zones, magmas cooled slowly, thus developing strong fabrics during large-scale dextral shearing. Ascent of residual liquids amidst the crystallizing solid framework was not recorded in the fabrics. However, these liquids were channelised through the gap and infilled the homogeneous shallow intrusions, where rapid cooling only permitted the development of feint, although wholly consistent, fabrics. q

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“…Malpas (1979) for the Bay of Islands aureole and Jamieson (1980) for the St Anthony Complex in western Newfoundland reported that Ti increases towards the peridotite contact. Raase (1974), Spear (1981) and Raase et al (1986) indicate that if temperature rises, amphibole becomes enriched in Ti in the presence of a Ti saturating phase. Thus, sphene could be a temperature indicator.…”

Section: Lycian Metamorphic Solementioning

confidence: 99%

Origin of metamorphic soles and their post‐kinematic mafic dyke swarms in the Antalya and Lycian ophiolites, SW Turkey

Çelik

Delaloye

2003

Geological Journal

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The Antalya and Lycian ophiolites are situated in the western part of the Tauride belt (SW Turkey). Ophiolite-related metamorphic sole rocks in the Tauride belt are observed either at the base of the tectonites or in mélange units. Geochemical observations from the metamorphic sole rocks of Köycegiz ophiolite indicate three different geochemical affinities: mid-ocean ridge basalt (MORB), island-arc tholeiite (IAT) and within-plate basalt (WPB) or seamount are present at the base of the Lycian ophiolites. The sole rocks of the ophiolite are made up of amphibolite, comprising mainly amphibole, pyroxene and plagioclase. Below the amphibolites are epidote-bearing rocks and, at the base, micaschists. The metamorphic sole below ophiolites exhibits an inverted metamorphic zonation. Very strong deformation within kyanite-garnet-bearing micaschists located far from the peridotites was observed, whereas the upper part of the metamorphic sole (near the contact with the peridotites) present relatively less deformation than the lower part.The metamorphic sole rocks of the Lycian ophiolite are cross-cut by some doleritic dykes with a typical greenschist facies mineral assemblage. However, while the metamorphic sole rocks exhibit well-developed lineation and foliation; the dykes lack such structures.

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Progressive Metamorphism of Mafic Rocks from Greenschist to Granulite Facies in the Dharwar Craton of South India

Cited by 139 publications

References 25 publications

Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

Syntectonic granite emplacement at different structural levels: the Closepet granite, South India

Origin of metamorphic soles and their post‐kinematic mafic dyke swarms in the Antalya and Lycian ophiolites, SW Turkey

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