High-resolution precipitation variations in the Northeast Tibetan Plateau over the last 800 years documented by sediment cores of Qinghai Lake

摘要: Short cores of about 80-cm retrieved from three main basins the deepwater areas in Qinghai Lake, largest inland enclosed lake China, were studied. Stable isotopes authigenic carbonates, grain-size, carbonate and organic matter content at 5-year resolution are used to reconstruct climatic history over last 800 years Northeastern Tibetan Plateau. Chronology was established according 210Pb dating 137Cs methods core correlation. It is found that different deep can be well correlated. The sedimentary rate highest western basin lowest east. In southern where short Qing-6 located, recent average sedimentation 0.1004 cm/yr. Variations effective precipitation recorded by oxygen grain size data during consistent with glacial accumulation record form Dunde Guliya ice cores. A dry climate lasted for 300 1200 AD 1500 AD, followed a wet period 1560 AD. two periods, 1650 1780 1850 results southwest monsoon weakening. generally increased since due strengthening Asian Southwest Monsoon, resulting until 1950s. Except early stage, Little Ice Age on Plateau characterized moisture. Organic content, nearly 200-year cycles, shows similar trend atmospheric delta carbon-14 before 1850s, indicating bioproductivity responds solar activity.