Plant-wax carbon isotopic evidence of Lateglacial and Holocene climate change from lake sediments in the Yin Mountains, inner Mongolia

Abstract

There is an ongoing debate about the hydroclimatic change during the Holocene and the last deglaciation in the mid-latitude of the Northern Hemisphere. We present an n-alkane and compound-specific carbon isotope record during the past 16.5 kyr BP from Lake Xijianhaizi in the Yin Mountain, on the northern margin of the East Asian summer monsoon region. In this cold region, where the vegetation is dominated by C3 plants, the long-chain n-alkanes (nC29-nC33) are predominantly derived from leaf wax lipids. The compound-specific carbon isotopic value of nC31 is sensitive to regional effective moisture. The results show that a relatively high effective moisture during the Bølling-Allerød (14.5–12.9 kyr BP) and the Younger Dryas (12.9–11.5 kyr BP), and low effective precipitation in the Pre-Boreal (11.5–11.0 kyr BP) and the late of the early Holocene (9.5–8.0 kyr BP). Since the early Holocene, a slight decreasing trend of δ13C31 in Lake Xijianhaizi implies increasing effective moisture. It may support the latitudinal temperature gradient would cause an increase in net precipitation in mid-latitude as suggested previously. The hydroclimate changes in this Alpine lake since the last deglaciation is different to the climatic change in southern China. In addition to uncertainties in proxy interpretation and dating, the huge topographical difference in northern China and strong seasonality might be one of the reasons for significant spatial hydrological differences among different localities.