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引用本文:殷勇,方念乔,胡超涌,聂浩刚,秦尊丽.云南中甸纳帕海古环境演化的有机碳同位素记录.湖泊科学,2001,13(4):289-295. DOI:10.18307/20010402
YIN Yong,FANG Nianqiao,HU Chaoyong,NIE Haogang,QING Zunli.Palaeoenvironmental Evolution Deduced from Organic Carbon Stable Isotope Compositions of Napahai Lake Sediments, Northwestern Yunnan, China. J. Lake Sci.2001,13(4):289-295. DOI:10.18307/20010402
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云南中甸纳帕海古环境演化的有机碳同位素记录
殷勇1, 方念乔2, 胡超涌3, 聂浩刚2, 秦尊丽2
1.南京大学大地海洋科学系, 南京 210093;2.中国地质大学, 北京 100083;3.中国地质大学, 武汉 430074
摘要:
中甸纳帕海位于云贵高原横断山脉腹地,其成因与碳酸岩类地层长期溶蚀有关.在丰水期和枯水期纳帕海的水位相差很大,枯水期常形成浅水池沼,因而造成枯水期和丰水期水生植被的发育状况有很大的差异.枯水期由于水生植物(飘浮和挺水植物)发育,造成总有机碳和氢指数的增加,有机碳同位素偏负,丰水期出现相反的演化趋势.进一步推论表明在暖干的气候条件下纳帕海极易形成枯水位,在冷湿的气候下可维持相对高的水位.古环境重建表明纳帕海在大约32kaBP和15kaBP出现环境的重大变迁,32-15kaBP出现高湖面.
关键词:  总有机碳和氢指数  13δCorg  古环境  中甸纳帕海
DOI:10.18307/20010402
分类号:
基金项目:国家自然科学基金(49672135);国家重点基础研究发展规划项目(G1998040800)
Palaeoenvironmental Evolution Deduced from Organic Carbon Stable Isotope Compositions of Napahai Lake Sediments, Northwestern Yunnan, China
YIN Yong1, FANG Nianqiao2, HU Chaoyong3, NIE Haogang2, QING Zunli2
1.Department of Geo and Ocean Sciences, Nanjing University, Nanjing 210093, P. R. China;2.China University of Geosciences, Beijing 100083, P. R. China;3.China University of Geosciences, Wuhan 430074, P. R. China
Abstract:
The Napahai Lake, situated in the hinterland of the Hengduan Mountains, is a basin by the erosion of carbonate rocks.The lake levels have experienced great fluctuation between low-stand and high-stand stages.The lake level changes di rectly inf luences the amount and distribution of aquatic plant communities that used different sources of carbon for photosy nthesis, thereby imprinting the organic sediments with a characteristic 13C composition.Ano ther reason influencing the 13C composition for bulk organic sediment, in this case, is the change of reduction-o xidation condition in the alternative stages.In addition with the strong dissolution of carbonate strata in humid-cool conditions, the lake level fluctuations and climatic changes could be reconstructed using HI, TOC and δ13C.The results show that increase in total organic carbon and hydrogen index correlates in general, with decrease in δ13C values, which could be at tributed to the flourishing of emerging and floating aquatic plants as well as a relative reduction envi ronment in a low lake level associated with a warm-dry or temperate-dry climate.The decreases of TOC and HI often correlate well with δ13C value increasing in a high lake level stage accompanied with a cool-humid climate, which might be att ributed to low productivity of aquatic plants, oxidation that triggers decomposition oforganic matters and strong dissolution of carbonate st rata in humid-cool conditions. The palaeo-environmental reconstruction shows that major environmental changes took place at 32kaBP and 15kaBP respectively.The lake levels exhibited frequent fluctuations between ca.57-43kaBP, and then the lake level slightly rose from ca.43kaBP to ca.37kaBP.After then, the lake level dropped dramatically when the climate became warm and dry.From ca.32kaBP, the lake level had a distinct rise due to cool-humid climate and kept high until the end of the Last Glacial Maximum.A warm-dry climate returned to the areas again and the lake level remained lowering during the Holocene.Af ter the lake level rose in a minor amplitude from ca.3 -2kaBP., modern climate dominates the Napahai lake.
Key words:  TOC  HI  13δCorg  environmental changes  Napahai Lake
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