青藏高原清水河多年冻土区湖沼环境变迁  

QINGSHUIHE LIMNETIC ENVIRONMENTAL CHANGE IN THE PERMAFROST REGION OF QINGHAI-XIZANG PLATEAU

作　　者：林清[1] 王国尚[1] 程国栋[1] 耿安松[2] 张干[2] 傅家谟[2] 

机构地区：[1]中国科学院兰州冰川冻土研究所冻土工程国家重点实验室,兰州730000 [2]中国科学院广州地球化学研究所有机地球化学国家重点实验室,广州510640

出　　处：《海洋与湖沼》1999年第6期744-750,共7页Oceanologia Et Limnologia Sinica

基　　金：国家自然科学基金!495721117;广州有机地球化学国家重点实验室基金!OGL-9403

摘　　要：1994年10月，利用钻探取样方法获得了位于青藏高原多年冻土区的清水河孔深为8．3m的Q1孔湖沼沉积物样品，对该IL50－640cm样品的有机地球化学分析结果表明，剖面样品中有机质具有相同的成熟度，且具有有机碳、氢指数、可溶有机质和族组成相同的变化特征。样品正烷烃碳数分布在C16－C35之间，主峰碳为C23，高碳数烷烃呈明显的偶奇优势，表明它们来源于植物。OEP值大于2，Pr／Ph均大于1，反映沉积环境处于氧化条件。藿烷和甾烷化合物组成随样品特征不同而异。由于藿烷和甾烷来源的特殊性，因而其组成可以反映湖沼中生物的特征。研究结果表明，剖面上有机质特征的差别能较好地记录该地湖沼环境的变迁。Organic geochemisny in frozen limnehc secliments can be used to recon struct the Paloenvironment because of good preservation of organic matter under low temperatUre. In thes work,an 830cm long core sample of the frozen limntic sediments was collected from Qngshinhe, a typical permafrost region in Qnghaiouzang plateau, and the orgedc matter in the core samples from 50-640cm has been studied. The orgahic matter, which has the same maturity, was mainly derived from the single species of high planL The content of total orgedc carbon (TOC), hydrogen index (HI), extracted orgboc mader (EOM) and the composition of groups have the same variations in this profile, suggeshng that at least four warmer climatic periods have occrmd in this region. In sediments from 135 to 180cm, the different distributions of normal alkans, which range from C16-C35 with the maximum of C23 and the remarkabe odtheven predondnance (OEP), and the different compositions of steranes and hopans mny imply the chanes of water depth and environmntal moistUre and temperature. At the same hme, the OEP and Pristane / Phytan (Pr / Ph, which are grether 2 and 1, respechvely, indicate tha the sedimenop environrnent was rich in oxygen and had a shallow water depth.

关 键 词：湖沼沉积 湖沼 环境变迁 清水河 多年冻土区 

分 类 号：P512.3[天文地球—地质学] P531