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Structural evidence supporting a remnant origin of patchy charnockites in the Chilka Lake area, India

  • S. Bhattacharya (a1), S. K. Sen (a1) and A. Acharyya (a1)

Abstract

Dark patches of charnockitic rocks characterized by orthopyroxene occur within garnetiferous granite gneisses (leptynites) in a granulite-migmatite suite around the Chilka Lake, Orissa, within the Eastern Ghats belt in the Indian Precambrian. Analysis of structures of different scales observed in this terrain establishes the presence of three phases of deformation. S1 is pervasive in the metapelitic granulites (mainlykhondalite), while in the migmatite complex composed of leptynites, charnockites and quartzofeldspathic veins, S1 is present exclusively within the charnockite lenses and bands, and shows different stages of obliteration in the associated leptynites. Thus, the charnockite patches must be earlier than the surrounding migmatitic rocks. The charnockite patches and the surrounding leptynitic gneisses are chemically quite different and the two rock types are not related by any prograde or retrograde transformation. The shapes and disposition of charnockite patches in the mixed exposures are found to be largely controlled by the third phase of folding and locally associated shearing. The kinematics of this late deformation are not favourable for fluid ingress from deeper levels.

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References

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Friend, C. R. L. 1981. Charnockite and granite formation and influx of CO2 at Kabbaldurga, Nature 294, 550–1.
Halden, N. M., Bowes, D. R. & Dash, B. 1982. Structural evolution of migmatites in granulite facies terrain: Precambrian crystalline complex of Angul, Orissa, India. Transactions of Royal Society of Edinburgh: Earth Science 73, 104–18.
Hansen, E. C., Janardhan, A. S., Newton, R. C., Prame, W. K. B. N. & Ravindra Kumar, G. R. 1987. Arrested charnockite formation in Southern India and Sri Lanka. Contributions to Mineralogy and Petrology 96, 225–44.
Pichamuthu, C. S. 1961. Transformation at Peninsular gneiss into charnockite in Mysore State, India. Journal of the Geological Society of India 2, 46–9.
Ravindra Kumar, G. R. & Chacko, T. 1986. Mechanisms of charnockite formation and breakdown in Southern Kerala: Implications for the origin of the Southern Indian granulite terrain. Journal of the Geological Society of India 28, 277–88.
Santosh, M. & Yoshida, M. 1986. Charnockite ‘in the breaking’: evidence from the Trivandrum Region, South Kerala. Journal of the Geological Society of India 28, 306–10.
Sarkar, A., Bhanumathi, L. & Balasubrahmanyan, M. N. 1981. Petrology, geochemistry and geochronology of the Chilka Lake igneous complex, Orissa State, India. Lithos 14, 93110.
Stähle, H. J., Raith, M., Hoernes, S. & Delfs, A. 1987. Element mobility during incipient granulite formation at Kabbaldurga, Southern India. Journal of Petrology 28, 803–34.

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