Branched aliphatic alkanes of shell bar section in Qarhan Lake,Qaidam Basin and their paleoclimate significance

作     者：ZHANG HuCai CHANG FengQin LI Bin LEI GuoLiang CHEN Yue ZHANG WenXiang NIU Jie FAN HongFang YANG MingSheng 

作者机构：Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Key Laboratory of Westem China's Environments MOE College of Earth Sciences and Environments Lanzhou University Lanzhou 730000 China 

出 版 物：《Chinese Science Bulletin》 (科学通报(英文版))

年 卷 期：2007年第52卷第9期

页      面：1248-1256页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

基　　金：Supported by the Hundred Talent Project of Chinese Academy of Sciences, the National Natural Sciences Foundation of China (Grant No.40371117) the Inno-vation Team Project of National Natural Sciences Foundation of China (Grant No.40421001) 

主　　题：柴达木盆地 察尔汗盐湖 贝壳堤剖面 侧链脂族烷 古气候意义 

摘      要：Biomarkers of paleolake deposits from Qarhan Salt Lake in Qaidam Basin,northwest China were sys-tematically analyzed and the A―C series compounds of branched aliphatic alkanes with quaternary substituted carbon atom(BAQCs) were identified. The homologous distinguished three series,A―C,were identified as 5,5-diethylalkanes,6,6-diethylalkanes and 5-butyl,5-ethylalkanes series,and their relative abundance was A B C. Series A and C were characterized by odd carbon numbers,whereas series B was characterized by even carbon numbers. The high values of series A corresponded with the high values of series B and C. Therefore,it can be concluded that series A,B and C possess a similar biological origin. The abundance of series A was relatively low in the lower part of the section compared with that in the upper part,implying that these series originated from bacteria and/or algae more prevalent in fresh-mesohaline water,and such kinds of bacteria and/or algae are most likely to be thermophilous species. The A25/nC25 ratio differences in the section show that such branched aliphatic alkanes can be treated as one kind of environmental change proxy for paleolake evolution and may provide important information for the climate reconstruction of the Late Pleistocene.