CHRONOSTRATIGRAPHY OF THE HIMALAYAN GLACIAL FLUCTUATIONS AT THE MILLENNIAL TIMESCALE DURING THE HOLOCENE

Understanding the response of the Himalayan glaciers to changing climate has been of immense concern to the scientific community. A central concern is our lack of knowledge about the close interaction between prevailing climate systems and mountain glaciers in the past, especially during the present interglacial when the northern Hemisphere experienced several abrupt short-duration changes in climate. While younger geomorphic records of glacial advances in the Himalayan orogen are widespread, they have not been utilized to establish the role of these short-term changes in climate forcing to glacial fluctuations. To address the problem we are developing a chronostratigraphy for Holocene glacial fluctuations in the Himalaya at a sub-millennial timescale resolution using mapping and cosmogenic surface exposure dating. Three detailed study areas in India are being examined: i) the arid northern Zanskar region of the northwest Himalaya; ii) the semi-arid transitional climatic zone of the Lahul Himalaya; and iii) the monsoon-influenced humid Khangchendzonga region of the Eastern Himalaya. Google Earth and IRS Cartosat-1 stereo pairs (2.5 m) digital elevation models are allowing us to map well preserved, abundant young moraines suitable for reconstructing millennial timescale chronology of glacial advances in these regions across the orogen. To better comprehend the distribution of the present climate system in the orogen we generated a climate zonation map using principal component analysis of the CRU CL 2.0 climate parameters, a 10' latitude/longitude resolution grid dataset of mean monthly surface climate conditions. In addition, published and new cosmogenic ¹⁰Be ages for moraines across the Himalaya are used to develop local and regional stages of Holocene glacial advances. We separate Gaussians from cumulative Probability Density Functions to trace the local stages and apply student’s t-test to develop regional stages. Initial studies that develop correlation with multiple proxy records for paleoclimate change suggest that glacial advances in the Himalaya are broadly correlated with abrupt cooling events and solar insolation minima during the Holocene. However, glacier advances during the early Holocene likely correlate with a strengthened monsoon influence in the orogen.