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Authors
Affiliations
1 Department of Marine Geology, Mangalore University, Mangalagangotri 574 199, IN
2 Birbal Sahni Institute of Paleobotany, 53 University Road, Lucknow 226 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No Spl Iss 3 (2006), Pagination: 447-459
Abstract
We have explored the potentia1 of using magnetic susceptibility( χif) as a proxy for past rainfall variations in a tropical region, and also the potentia1 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 smaH tank near Chitradurga town, Karnataka, exhibits considerable fluctudtions in χif Discountlng the possibilitestres of magnetite from biogenic and anthropogenic sources and of dissolutio of magnetic minerals, the χif signal must be related principally to rainfall in the tank-catchment There is a good correlation of χif with instrumental rainfall data (r = 0 65 for Peninsular India, r = 0 45 for Chitradurga Stationa)n d histoncally recorded rainfall events Presuming that χif variations are produced mainly by rainfall variations and that there was no signtficant human impact in the catchment and no slumping or bioturbatio of sediments we have reconstructed the paleorainfall profile for thc last 3,700 years for Chitradurga region The profile is chronologically constrained by two I4c dates Several events of drought and high rainfall, and onset of aridity are corretatable with similar events documented in speleothems from chfferent parts of india, a tree-ring from western India and lake sediments from Rajasthan We have thus shown that χif 1s a proxy for rainfall in tropical regions and that tank-bed sediments from tropical lndia are an important archive of paleorainfall/paleoclimate data.
Keywords
Tank-bed sediments, Southern India, Magnetic susceptibilty Rainfall reconstruction, Paleoclimate, Southwest monsoon, Late Holocene, Little Ice Age.
