The Paleoenvironmental Significance of 87Sr/86Sr Derived from Peat Successions over the Past ~50 000 Years on Northern Leizhou Peninsula,North Tropic China

In this paper, we use the data of strontium isotope ratios (87Sr/86Sr) of two peat successions, which were obtained at Xialu village in Suixi County and Wushan village near Zhanjiang city in northern Leizhou Peninsular, to explore the paleoenvironmental significance of 87Sr/86Sr of peat sequences in northern tropical China. Results show that values of 87Sr/86Sr ratio in the peat sequences vary between 0.713 and 0.722 with a mean of 0.716 in the past ~ 50000 years. Based on climatic variations reflected by multi-proxy records, we find that on the orbital scale the 87Sr/86Sr ratio exhibits relatively low values under wet and warm conditions (e.g., in Marine isotopic stage 3, MIS 3), whereas in dry and cool period such as MIS 2, 87Sr/86Sr ratio shows relatively high values. This phenomenon was also reflected on millennial-scales climatic variations. The mechanism resulting in variations of 87Sr/86Sr ratio in the peat successions may relate to the input of the residual silicate clastics, which have been weathered and leached in the catchment. On the other hand, changes in surface runoff as well as vegetation conditions may play a role in influencing input of strontium element as well. Our results reveal that the 87Sr/86Sr record in peat successions in north tropic China is an effective proxy to indicate changes of chemical weathering intensity in the catchment, which are closely related to evolution of Asian summer monsoon.