Palaeoclimate reconstructions on various timescales using stalagmites from Meghalaya, NE India, and applying U/Th dating, stable isotopes and element studies

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Speleothems provide very useful palaeoclimate records which can be accurately dated. On the Indian sub-continent only few such well-dated records are available to date. We propose to study stalagmites from NE India, a regional gap in these efforts. In a ground-truthing study, a broad array of techniques will be applied to understand how monsoon-related climate signals are recorded in speleothems from this region. Age determinations of speleothems will be carried out at CalTech in cooperation with J. Adkins. Parallel to stable isotope (δ18O and δ13C, δ34S), laser ablation trace element and grey-scale analysis will be applied. Pilot investigations will be conducted on stalagmites to explore their potential for extending the radiocarbon calibration scale beyond the range of tree ring chronology by using U/Th dates coupled with 14C and 10Be studies. We plan to study carbonate-associated organic N and nitrate. Proxy results will be calibrated against meteorological data. The resulting calibrations will then be applied in the development of records of multiple climate-sensitive parameters in speleothems from the same cave system. The overall goal is to produce high quality paleoclimatic reconstructions for the region on a variety of timescales, and to interpret those reconstructions in terms of climate forcing.