High-resolution monsoon reconstruction using an annually resolved stalagmite from Kotumsar cave, India

Wednesday, 17 December 2014
Shraddha Tukaram Band1, Madhusudan G Yadava2, Kaushik Sree2, R. Ramesh2, Victor J Polyak3 and Yemane Asmerom4, (1)Physical Research Laboratory, Ahmedabad, India, (2)Physical Research Laboratory, Geosciences Division, Ahmedabad, India, (3)University of New Mexico Main Campus, Albuquerque, NM, United States, (4)University of New Mexico Main Campus, Earth and Planetary sciences, Albuquerque, NM, United States
A stalagmite sample that grew between ~5000 and 4000 year BP, collected from Kotumsar cave (Chhattisgarh, India) shows annual laminations of ~1mm thickness. Sub-sampling for stable isotope analysis was carried out using micro-mill with spatial resolution of ~200 micrometer to resolve seasonal changes. The monsoon variability is reconstructed using δ18O and δ13C measured on DeltaV-plus IRMS. Six clusters of enriched δ18O and δ13C values in the reconstructed time series are identified as mega-drought events. Earlier archaeological evidences such as burnt charcoal, millets and grasses, suggesting dwelling site for prehistoric man, were reported from this cave. These are drought tolerant crops, and grow in low rainfall regions. Radiocarbon ages of some of the charcoal remains seem to be contemporary with the stalagmite drought events suggesting that caves were used as shelter during severe drought conditions.