A multi-decadal rock magnetic record of monsoonal variations during the past 3,700 years from a tropical Indian tank

R. Shankar, C. N. Prabhu, A. K. Warrier, G. T. Vijaya Kumar, B. Sekar

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43 Citations (Scopus)


We have explored the potential of using magnetic susceptibility (X lf) as a proxy for past rainfall variations in a tropical region, and also the potential of tank-bed sediments from Southern India as a paleoarchive. The 3,700-year rock magnetic record from Thimmannanayakanakere (14°12′N; 76°24′E), a small tank near Chitradurga town, Karnataka, exhibits considerable fluctuations in X lf. Discounting the possibilities of magnetite from biogenic and anthropogenic sources and of dissolution of magnetic minerals, the X lf signal must be related principally to rainfall in the tank-catchment. There is a good correlation of X lf with instrumental rainfall data (r = 0.65 for Peninsular India; r = 0.45 for Chitradurga Station) and historically recorded rainfall events. Presuming that X lf variations are produced mainly by rainfall variations and that there was no significant human impact in the catchment and no slumping or bioturbation of sediments, we have reconstructed the paleorainfall profile for the last 3,700 years for Chitradurga region. The profile is chronologically constrained by two 14C dates. Several events of drought and high rainfall, and onset of aridity are correlatable with similar events documented in speleothems from different parts of India, a tree-ring from western India and lake sediments from Rajasthan. We have thus shown that X lf is a proxy for rainfall in tropical regions and that tank-bed sediments from tropical India are an important archive of paleorainfall/paleoclimate data.

Original languageEnglish
Pages (from-to)447-459
Number of pages13
JournalJournal of the Geological Society of India
Issue number3
Publication statusPublished - 01-09-2006

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences (miscellaneous)


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