International Journal of Earth Sciences and Engineering

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Genesis of Gibbsite and Palaeoclimatic Conditions Deciphered from O and H Isotopes:A Case Study from Deccan Basalt-Derived Lateritic Residuum, India


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

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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  • Genesis of Gibbsite and Palaeoclimatic Conditions Deciphered from O and H Isotopes:A Case Study from Deccan Basalt-Derived Lateritic Residuum, India

Abstract Views: 168  |  PDF Views: 118

Authors

M. S. Sethumadhav
Department of Studies in Earth Science, University of Mysore, Manasagangotri, Mysore-570006, India
K. N. Somashekar
Department of Studies in Earth Science, University of Mysore, Manasagangotri, Mysore-570006, India
Torsten Vennemann
University of Lausanne, Institute of Earth Surface Dynamics, Lausanne, Switzerland

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.