An isotopic study on water system of Lake Barkol and its implication for Holocene climate dynamics in arid central Asia

Mechanism of arid central Asia climate dynamics is still an open question even it has been studied for a long time. Interpreting climatic proxy data properly is crucial for better understanding the paleoclimate in such a sensitive area and its role in the earth system. According to the analysis of water stable isotope (δ18O and δD), Lake Barkol catchment obeys the typical isotopic model of a hydrologically closed lake: Lake input water inherits the feature of the weighted mean annual isotopes in precipitation, and lake water isotopes move along the local evaporation line from the start point of input water isotopes, modulated by the regional effective moisture. Based on the modern water isotopes and its relation to the climate, sediment carbonate oxygen isotope (δ18Ocarb) record re-interpretation suggests that the Asian monsoon incursion to arid central Asia area alone is unlikely the reason for the early Holocene δ18Ocarb negative, as the calculated extreme summer rainfall δ18O change to compensate the more negative δ18Ocarb in the early Holocene is far beyond our knowledge of precipitation isotopes in the real world. Besides, a 40 % of winter precipitation increase could explain the δ18O negative change in the early Holocene, which does, more importantly, reconcile the contradiction between the pollen Aretemisia/Chenopodiaceae effective moisture and δ18O records.