Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

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Geochemistry and Petrogenesis of the Champawat Granitoids Occurring around Dhunaghat, District Pithoragarh, Uttar Pradesh, India


Affiliations
1 Department of Geology, Kumaun University, Nainital 263 002, India
2 Geology Laboratory, Department of Civil Engineering, Institute of Technology, Banaras University, Varanasi-221 005, India
3 Australian Geological Survey Organisation, P. O. Box 378, Canberra City, A.C.T. 2601, Australia
     

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Early Cambrian Champawat granitoids from Dhunaghat area, emplaced between medium-to high-grade metapelites of the Saryu Formation and low-grade melapelites of the Gumalikhet Formation of the Almora Group, show wide variations in their modal and chemical composition, ranging from granodiorite to granite. Biotite-rich mafic enclaves within the granitoids may represent restile, possibly modified by metasomatism. Chemical data for the calc-alkaline Champwat granitoids show some dcgree of fractional crystallization, although processes such as restite unmixing and different degree of melting may also have been important for the observed variation trends.

The Champwat intrusives are also characterized by enrichment of Y, Zr, Th, U, Nb, La, Ce, Pr and Nd and show affinities with "A"-type (anorogenic) granites.


Keywords

Geochemistry, Petrogenesis, Champawat graniloids, Almora Group, Dhunaghat, District Pithoragarh, Uttar Pradesh.
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  • Geochemistry and Petrogenesis of the Champawat Granitoids Occurring around Dhunaghat, District Pithoragarh, Uttar Pradesh, India

Abstract Views: 172  |  PDF Views: 1

Authors

B. N. Singh
Department of Geology, Kumaun University, Nainital 263 002, India
O. P. Goel
Department of Geology, Kumaun University, Nainital 263 002, India
Mallickarjun Joshi
Geology Laboratory, Department of Civil Engineering, Institute of Technology, Banaras University, Varanasi-221 005, India
J . W. Sheraton
Australian Geological Survey Organisation, P. O. Box 378, Canberra City, A.C.T. 2601, Australia

Abstract


Early Cambrian Champawat granitoids from Dhunaghat area, emplaced between medium-to high-grade metapelites of the Saryu Formation and low-grade melapelites of the Gumalikhet Formation of the Almora Group, show wide variations in their modal and chemical composition, ranging from granodiorite to granite. Biotite-rich mafic enclaves within the granitoids may represent restile, possibly modified by metasomatism. Chemical data for the calc-alkaline Champwat granitoids show some dcgree of fractional crystallization, although processes such as restite unmixing and different degree of melting may also have been important for the observed variation trends.

The Champwat intrusives are also characterized by enrichment of Y, Zr, Th, U, Nb, La, Ce, Pr and Nd and show affinities with "A"-type (anorogenic) granites.


Keywords


Geochemistry, Petrogenesis, Champawat graniloids, Almora Group, Dhunaghat, District Pithoragarh, Uttar Pradesh.