Deformational history of the Precambrian Kolar Schist Belt,South India: Constraints for the tectonic evolution |
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| Authors: | Dilip K Mukhopadhyay |
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| Institution: | (1) Department of Earth Sciences, University of Roorkee, 247667 Roorkee, India |
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| Abstract: | In the Kolar Schist Belt well-preserved small-scale diastrophic structures suggest four phases of folding (F1 — F4). The near coaxial F1 andF
2folds are both isoclinal with long-drawn out limbs and sharp hinges. The axial planes of bothF
1andF
2folds are subvertical with N-S strikes; these control the linear outcrop pattern of the Schist belt. The later folds (F
3and F4) are important in small-to-intermediate scales only and are accommodation structures formed during the relaxation period
of the early folding episodes. Mesoscopic shear zones, post-F2 but pre-F3 in age, are present in all the rock types in this area. The F1 and F2 folds and the mesoscopic shear zones were formed during a continuous E-W subhorizontal compression. Available geochemical
and isotopic data show that the Kolar Schist Belt with ensimatic setting is bounded by two granitic terrains of contrasting
evolutionary histories. This, together with E-W subhorizontal compression over a protracted period of time, strengthens the
recent suggestions that the Kolar Schist Belt represents a suture. This belt then marks the site of a continent-continent
collision event of late Archaean-early Proterozoic age. |
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| Keywords: | Kolar Schist Belt structural history superposed folding Precambrian tectonics deformational events gneisses |
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