| 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，对该孔50–640cm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。 |
| 关键词: 青藏高原 冻结湖沼沉积 有机质地球化学 湖沼环境变迁 |
| DOI： |
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| 基金项目:国家自然科学基金“青藏高原浅层冻结湖相沉积有机质地球化学和古环境”资助项目，495721117;广州有机地球化学国家重点实验室基金“冻土湖相沉积有机质地球化学”资助项目，OGL-9403号 |
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| QINGSHUIHE LIMNETIC ENVIRONMENTAL CHANGE IN THE PERMAFROST REGION OF QINGHAI–XIZANG PLATEAU |
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LIN Qing1, WANG Guo-shang1, CHENG Guo-dong1, GENG An-song2, ZHANG Gan2, FU Jia-mo2
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1.State Key Laboratory of Frozen Soil Engiheering, Lanzhou Institute of Glaciology and GeocryologyThe Chinese Academy of Science, Lanzhou, 73000;2.State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, The Chicese Academy of Science, Guangzhou, 510640
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| Abstract: |
| Organic geochemistry in frozen limnetic sediments can be used to recon struct the paloenvironment because of good preservation of organic matter under low temperature. In this work, an 830cm long core sample of the frozen linmetic sediments was collected from Qingshuihe, a typical permafrost region in Qinghai–Xizang plateau, and the organic matter in the core samples from 50–640cm has been studied. The organic matter, which has the same maturity, was mainly derived from the single species of high plant. The content of total organic carbon (TOC), hydrogen index (HI), extracted organic matter (EOM) and the composition of groups have the same variations in this profile, suggesting that at least four warmer climatic periods have occurred in this region. In sediments from 135 to 180cm, the different distributions of normal alkanes, which range from C16–C35 with the maximum of C23 and the remarkable odd-even predominance (OEP), and the different compositions of steranes and hopanes may imply the changes of water depth and environmental moisture and temperature. At the same time, the OEP and Pristane/Phytane (Pr/Ph),which are greater 2 and 1, respectively, indicate that the sedimentary environment was rich in oxygen and had a shallow water depth. |
| Key words: Qinghai–Xizang plateau, Frozen limnetic sediments permafrost region, Organic geochemistry, Limnetic environmental change |
