CLIMATIC CHANGES IN HIAMALAYAN REGION FROM STABLE ISOTOPE RECORD OF VARVED SEDIMENTS FROM A PALAEOLAKE IN GOTING, GARHWAL

18O/16O variations of the precipitation recorded in carbonate sediments of a high altitude Himalayan lake have been investigated by analyzing samples from a varve deposit in Goting, Garhwal Himalaya. 14C ages of 4 samples from different depths suggest that the sedimentation in the lake started ~42,000 year BP and continued till ~28,000 year BP. Fluctuations in d18O values are interpreted in terms of water source variations. High d18O values from 33 ky to 28 ky indicate a major dry phase. There are three strong d18O excursions (depleted ratios) coinciding with low 13C values, indicating abrupt climatic fluctuations. These events at around 36.5 ky, 34.7 ky and 33 ky BP marked major enhancement of south west monsoon. But two excursions at 41 ky and 38.6 ky are not correlated with low d13C values; these events were probably caused by increased supply from glacier melt. Comparisons are made between the 18O/16O of carbonate cements at Goting, located in a region with pronounced influenced from Westerlies as compared to South west monsoon dominated Dulam lake. d13C of organic matter from Dulam sediments inherit signature of C3 vegetation during 30 to 31 k year, coinciding with the periods with major enhancement of south west monsoon. Fourier analysis shows a significant ~740 year periodicity in 18O/16O of carbonate cements in Goting, similar to that reported in the Arabian sea and south China sea. This could be related to a regional level century scale variation in the south west monsoon.