TROPICAL GEOGRAPHY ›› 2015, Vol. 35 ›› Issue (4): 592-600.

Climatic Characteristics Indicated by the Variations of Rb/Sr in the Liukuang Section during the Last Glacial Period

LI Zhiwen1,2，LI Baosheng3，SUN Li2，WANG Fengnian4

1. （1．Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology，Ministry of Land and Resources，Qingdao 266071，China； 2．School of Earth Science，East China University of Techology，Nanchang 330013，China；3．School of Geography，South China Normal University，Guangzhou 510631，China；4．Department of Tourism，Huizhou University，Huizhou 516007，China）
• Online:2015-07-03 Published:2015-07-03

Abstract:

Liukuang Red bedding of the Last Glacial is located near Chenshantou in the north of Shandong Peninsula. Based on the field investigation, we found the Liukuang section mainly consists of the alternating deposition of dune sands and paleosol or lacustrine, and its geological age is 13.1-78.9 ka BP. According to the analysis of the contents of Rb, Sr, Rb/Sr ratio and other mineral composition, we got the conclusion as follows: 1) Rb and Sr are released by the decomposition of instable minerals, especially by the potash feldspar and plagioclase, and their amount is increasing as the weathering strengthens. Rb is absorbed and Sr is leaching because of their different geo-chemical properties, which led to the different Rb contents in different sedimentary facies, that in dune sand< sandy paleosol < lacustrine < silty paleosol, and the Sr contents also varying in different sedimentary facies, that in dune sand > lacustrine > sand paleosol >silty paleosol. 2) The value of Rb, Sr and Rb/Sr ratios shows remarkable variations in alternation of peaks and valleys, of which LKS4 and LKS2 represent cold periods and LKS3 represents warm period which includes LKS3b cold period and LKS3a and LKS3c warm periods. It suggests the climate variations on ten-millennium scale. These warm periods mainly correspond to strong summer monsoon indicated by stalagmite in Hulu Cave in China, as well as the peak of total amount of astronomical insolation at 65°N in July, and cold periods correspond to weak summer monsoon and low value of total amount of insolation, which reveals that the climate changes in the Liukuang section during the Last Glacial period probably results from the mutual impact of total amount of insolation and East Asian summer monsoon.