JIN, ZHANGDONG, BICKLE, MIKE J., CHAPMAN, HAZEL J., YU, JIMIN, AN, ZHISHENG, WANG, SUMIN, and GREAVES, MERVYN J.
Jin, Z. D., Bickle, M. J., Chapman, H. J., Yu, J., An, Z., Wang, S. & Greaves, M. J. 2010: Ostracod Mg/Sr/Ca and Sr/Sr geochemistry from Tibetan lake sediments: Implications for early to mid-Pleistocene Indian monsoon and catchment weathering. Boreas, 10.1111/j.1502-3885.2010.00184.x. ISSN 0300-9483 Lacustrine sediment serves as a valuable archive for tracing catchment weathering processes associated with past climatic and/or tectonic changes. High-resolution records of fossil ostracod Mg/Ca, Sr/Ca and Sr/Sr ratios from a lake sediment core from the central Tibetan Plateau reveal a temporal link between lake-water chemistry and catchment weathering and distinct monsoonal oscillations over the early to mid-Pleistocene. Between 2.01 and 0.95 Ma, lake-water chemistry was dominated by a high proportion of carbonate weathering related to variations in the Indian monsoon, resulting in relatively low and constant ostracod Sr/Sr but obvious fluctuations in Mg/Ca, Sr/Ca and δO. Across the mid-Pleistocene transition (MPT), a significant increase in Sr/Sr and frequently fluctuating ratios of ostracod Mg/Ca, Sr/Ca and δO are coincident with increases in both Chinese loess grain size and Arabian Sea lithogenic flux. This correlation indicates an increased glaciation and a strong monsoon seasonal contrast over the plateau. The increase in lake-water Sr/Sr across the MPT highlights a change in catchment weathering patterns, rather than one in climate-enhanced weathering intensity, with an increased weathering of Sr-rich minerals potentially induced by marked extensive glaciation and strong seasonality in the central plateau. [ABSTRACT FROM AUTHOR]