International Journal of Earth Sciences and Engineering

M. S. Sethumadhav ¹, K. N. Somashekar ¹, Torsten Vennemann ²

Affiliations
1 Department of Studies in Earth Science, University of Mysore, Manasagangotri, Mysore-570006, IN
2 University of Lausanne, Institute of Earth Surface Dynamics, Lausanne, CH

Abstract

Stable O and H isotope compositions were measured of pure mineral separates of weathering minerals (gibbsite and kaolinite) from lateritic residuum developed over Deccan basalt in the Kolhapur district, Maharastra. The δ¹⁸O (‰, VSMOW) versus δD (‰, VSMOW) values of gibbsite samples range from 2.50 to 7.41 and -50 to -53, respectively, and those for kaolinite samples range from 16.4 to 17.8 and -73 to -77, respectively. Plots of isotope data of gibbsite on a bivariate δ¹⁸O versus δD diagram indicate that the analyzed gibbsites are of secondary origin. The calculated values of δ¹⁸O water in equilibrium with gibbsite suggest their formation under intense monsoonal conditions, significantly different from the present day climate of the study area.

Keywords

Gibbsite and Kaolinite, India, Lateritic Residuum, O and H Isotopes, Palaeoclimate.

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