New insights on the age of the Mengyejing Formation in the Simao Basin,SE Tethyan domain and its geological implications  

作　　者：Maodu YAN Dawen ZHANG Xiaomin FANG Weilin ZHANG Chunhui SONG Chenglin LIU Jinbo ZAN Miaomiao SHEN 

机构地区：[1]Key Laboratory of Continental Collision and Plateau Uplift,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [2]Center for Excellence in Tibetan Plateau Earth Sciences,Chinese Academy of Sciences,Beijing 100101,China [3]College of Tourism and Environmental Resource,Zaozhuang University,Zaozhuang 277160,China [4]University of Chinese Academy of Sciences,Beijing 100049,China [5]School of Earth Sciences,Key Laboratory of Western China’s Mineral Resources of Gansu Province,Lanzhou University,Lanzhou 730000,China [6]MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China

出　　处：《Science China Earth Sciences》2021年第2期231-252,共22页中国科学（地球科学英文版）

基　　金：supported by the National Basic Research Program of China(Grant Nos.2011CB403000,2017YFC0602803);the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA20070201);the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0707);the National Natural Science Foundation of China(Grant Nos.41988101,41907263,41974080);the Funding of the Qingtan Scholar Talent Project of Zaozhuang University。

摘　　要：Knowledge on the origin and mechanism of the large potash formation in the southeast Tethyan tectonic domain are still under debate,one of which mainly due to the controversial ages of the potash-bearing strata.Here we present a detailed detrital zircon U-Pb geochronologic-magnetostratigraphic study of the potash-bearing Mengyejing(MYJ)Formation(Fm)from the Simao Basin.948 paleomagnetic cores and 4 detrital zircon U-Pb samples were collected from a 932-m thick Jiangcheng section.Thermal demagnetization isolated 857 primary characteristic remnant magnetization(ChRM)directions,indicated by positive reversals and fold tests and petrologic examinations.Seven normal and seven reversed polarity zones were identified and correlated well with chrons C27r to C34n of the geomagnetic polarity timescale(GPTS2012),yielding the first known age sequence of>112 to~63 Ma for the MYJ Fm.The ages for the potash bearing strata in the Simao commenced~20 Ma earlier than those in the adjacent Khorat basins,opposite to the traditional viewpoint that the former would rather correspond to the middle and lower parts of the latter.Given the paleogeographic reconstruction of likely a pan-Simao-Khorat basin during the Cretaceous,~85 Ma would be another important potential period for future potash exploration in the Simao Basin.

关 键 词：Simao Basin MAGNETOSTRATIGRAPHY Potash-bearing sequence Mengyejing Fm >112–~63 Ma Potash formation 

分 类 号：P619.211[天文地球—矿床学]