Southwest monsoon changes indicated by oxygen isotope of ostracode shells from sediments in Qinghai Lake since the late Glacial

The delta O-18 records of ostracode shells in sediments of core QH-2000 from Qinghai Lake can be used as a better proxy to reflect monsoon changes. Low monsoon precipitation between 17.5 and 11 cal. ka BP is indicated by positive delta O-18 values averaging 2.37 parts per thousand. A fast shift in 5180 from positive at 11 cal. ka BP to negative at 10 cal. ka BP indicates sharp increase of monsoon precipitation. An interval of generally high monsoon precipitation is observed between 10 and 6 cal. ka BP with delta O-18 values averaging -2.15 parts per thousand. Decrease of monsoon precipitation between 6 and 2.5 cal. ka BP is indicated by positive delta O-18 values. delta O-18 keeps positive values averaging 3.0 parts per thousand between 2.5 and 0 cal. ka BP suggesting low high monsoon precipitation. The climatic changes indicated by delta O-18 records of ostracode shells in sediments of core QH-2000 from Qinghai Lake and our broader regional comparison show that the climate in Qinghai Lake since the late Glacial is probably controlled by southwest monsoon other than southeast monsoon.