| 云南兰坪盆地古近系云龙组上段沉积环境研究——来自碳、氧同位素的证据 |
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| 关键词:Lanping basin Yunlong Formation carbon and oxygen isotopic composition paleoenvironment PETM |
| 基金项目:国家重点基础研究发展计划项目(编号: 2011CB403007) |
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| A Study of the Sedimentary Environment of the Upper Member of the Paleogene Yunlong Formation in Lanping Basin, Yunnan Province: Evidence from Carbon and Oxygen Stable Isotopes |
| Yunlong salt-bearing Formation in Lanping basin was formed in a strong arid environment in Paleogene. Yunlong Formation archived an entire first-class circle in the lake evolution, i.e., a fresh lake became a salt lake, then evolved into a playa and finally turned back to be a fresh lake again. Limestone strata were deposited in the upper Yunlong Formation. The authors collected 25 limestone samples in the upper Yunlong Formation, and the analysis of these samples shows that the δ13C and δ18O values range from –13.13‰ to –6.67‰ and from –15.55‰ to –13.90‰ respectively, with the average value of δ13C being –11.57‰, and that of δ18O being –15.02‰, and the correlation coefficient of δ13C and δ18O values is 0.57. According to Z values of all samples (ranging from 92 to 107, all lower than 120) and the composition of carbon isotopes, the lake was likely a continental fresh or brackish lake at that time, with relatively low water salinity. According to the empirical equation of paleotemperature calculation, the temperatures range from 35.5℃ to 44.3℃, averagely 41.4℃. The paleotemperature is relatively high, and might be correlated with M. Therefore, the paleoclimate was dry and hot during the generation of Yunlong Formation, and the termination of evaporite deposition was mainly caused by an open lake environment. |
| SHEN Li-jian,LIU Cheng-lin,WANG Li-cheng.2016.A Study of the Sedimentary Environment of the Upper Member of the Paleogene Yunlong Formation in Lanping Basin, Yunnan Province: Evidence from Carbon and Oxygen Stable Isotopes[J].Acta Geoscientica Sinica,37(3):301-306. |
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