| 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 |
| 点此下载全文 |
| 引用本文：沈立建,刘成林,王立成.2016.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[J].地球学报,37(3):301-306. |
| DOI：10.3975/cagsb.2016.03.06 |
| 摘要点击次数: 2724 |
| 全文下载次数: 2565 |
|
| 基金项目:国家重点基础研究发展计划项目(编号: 2011CB403007) |
|
| 中文摘要:云南兰坪盆地古近系云龙组地层记录了盆地由淡水湖泊→盐湖、干盐湖→淡水湖泊沉积的一个完整的Ⅰ级韵律。在云龙组上段沉积了一套灰岩地层, 上覆于云龙组上段含盐层之上, 对此套灰岩共取样25个, 测试结果显示, δ13C和δ18O均为负值, δ13C介于–13.13‰ ~ –6.67‰之间, 均值为–11.57‰, δ18O介于–15.55‰ ~ –13.90‰之间, 均值为–15.02‰, δ13C和δ18O具有较小相关性(0.57), 表明当时湖泊封闭性较差。根据Z值和δ13C表明, 当时为陆相淡水或微咸水湖泊沉积, 含盐度较低。根据经验公式计算所得温度为35.5~44.3℃, 平均为41.4℃。相对于现代湖水温度, 当时水体温度较高, 可能与PETM事件有关。因此, 整个云龙组沉积时期气候炎热干旱, 造成蒸发岩沉积中断的主要原因为湖泊的封闭性降低。 |
| 中文关键词:兰坪盆地 云龙组 碳、氧同位素 沉积环境 PETM |
| |
| 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 |
|
|
| Abstract: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. |
| keywords:Lanping basin Yunlong Formation carbon and oxygen isotopic composition paleoenvironment PETM |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|
