An oxygen isotope record from Lake Xiarinur in Inner Mongolia since the last deglaciation and its implication for tropical monsoon change

摘要

We present a high-resolution oxygen isotope record from authigenic carbonate (delta O-18(carb)) from Lake Xiarinur (Inner Mongolia) since the last deglaciation. The lake is located at the modem northern limit of the monsoon, and is therefore sensitive to the extension of the East Asian summer monsoon. Based on calibration against the instrumental record, the delta O-18(car) variation has been interpreted as changes in atmospheric circulation pattern on decadal time scales. On longer time scales, the delta O-18(carb) in lake sediments could be mainly regulated by the relative contribution of nearby (remote) water-vapor sources associated with subtropical (tropical) monsoon through changes in the distance from sources to the site of precipitation. Increased remote water vapors from tropical monsoon would lead to lighter isotope value in our study site. Through time the delta O-18(carb) record in Lake Xiarinur indicate a notable weak tropical monsoon during the Younger Dryas, a gradual increasing monsoon from the early Holocene and weakening monsoon after the middle Holocene. Oxygen isotope records from lakes and stalagmite in the Asian monsoon region across different localities show a general similar temporal pattern since the last deglaciation, and highlight a fundamental role of the tropical monsoon.