INFERRED HOLOCENE MONSOON RAINFALL AND LAKE LEVELS IN EASTERN TIBETAN LAKES

Southeastern Asia is reliant on the Indian summer monsoon (ISM) for meeting its annual water needs. The Tibetan Plateau is a vital part of the water budget for the region as it contains headwaters of all major rivers in the region. Predictions of future monsoon rainfall intensity and volumes is reliant on a combination of the short meteorological record from the area and interpretations of monsoon intensities derived from paleoclimate records. Lake sediments are an important archive of fluctuations in rainfall and respective changes in lake levels. In this ongoing study, we are using lake sediment records to provide a longer record of relative levels of precipitation and lake level during the monsoon season. We have collected sediment cores from five lakes along an east-west transect in the Eastern Tibetan Plateau. The primary goal of this project is to assess temporal and spatial variations in the intensity of the ISM throughout the Holocene. We are utilizing multiple proxies to assess paleo-precipitation and lake level including sedimentology, grain sizes, geochemistry, terrestrial and aquatic leaf wax isotopes, and diatom community assemblages. Preliminary records from our lakes indicate regional trends in monsoon strength, with higher lake levels in the Early Holocene, but with greater lake stand variability in the Late Holocene. These paleoclimate reconstructions furthers our understanding of strong versus weak monsoon intensities and can be incorporated in climate models for predicting future monsoon conditions.