| 藏北乌兰乌拉湖地区第三纪陆相红层古地磁研究的初步结果及地质意义 |
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| 关键词:magnetostratigraphy Tertiary continental redbeds Tibetan plateau |
| 基金项目:国家自然科学基金项目“青藏高原可可西里地区早新生代古气候记录”(编号:40025107)，“乌兰乌拉湖幅1∶25万区域地质调查”(编号:200013000147) |
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| Magnetostratigraphic Studies of Tertiary Continental Redbeds in Wulanwula Lake Area of Northern Tibetan Plateau and Their Geologic Significance |
| A total of 156 individual oriented samples were collected from Tertiary continental red beds in the upper lithologic unit of the Fenghuoshan Group within Wulanwula Lake area, northern Tibetan plateau. Rock magnetic measurement and demagnetization analysis were performed at the paleomagnetism laboratories of the University of California, Santa Cruz, USA. Most samples exhibited two components of magnetization in thermal demagnetization experiments. The most stable high-unblocking temperature components were isolated and passed positive reversal and fold tests at the 95% confidence level. The polarity patterns from the red bed sequence show that a reliable magnetostratigraphy can be established. Its normal polarity intervals are correlated with C23n-C20n of the geomagnetic polarity time scale (GPTS). The age of measured Fenghuoshan Group section is paleomagnetically dated as 52～42 Ma (Middle Eocene) and defined by K-Ar isotopic dating of discrete intrusion dikes. This suggests that the Fenghuoshan Group is a diachronic lithostratigraphic unit across paleo-suture zone and its deposition occurred synchronously with the Indian and Eurasian continental collision. |
| YI Hai-sheng,Zhao Xixi,LIN Jin-hui,SHI Zhi-qiang,LI Bao-hua,ZHAO Bing.2004.Magnetostratigraphic Studies of Tertiary Continental Redbeds in Wulanwula Lake Area of Northern Tibetan Plateau and Their Geologic Significance[J].Acta Geoscientica Sinica,25(6):633-638. |
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