Laser probe40Ar/39Ar dating of mica on the deformed rocks from Altyn Fault and its tectonic implications, western China |
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Authors: | Yongjiang Liu Huiwen Ye Xiaohong Ge Wen Chen Junlai Liu Shoumai Ren Hongxun Pan |
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Institution: | (1)College of Earth Sciences, Changchun University of Science and Technology ,Changchun 130061 ,China;
(2)Graduate School, China University of Geosciences ,Beijing 100083 ,China;
(3)Laboratory of Isotopic Geochronology, Institute of Geology, Ministry of Land and Resources of China ,Beijing 100037 ,China |
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Abstract: | The samples of Caledonian mylonitized granite and Jurassic meta-sedimentary rocks were collected in the north of Dangjinshan Pass, Qaidam gate fault-valley and Gesi fault-valley. Detailed studies under the microscope and electronic microscope suggest that all the samples contain the syntectonic-growing minerals such as white mica, chlorite, sericite, biotite, etc. By dating these minerals, we got a group of 40Ar/39Ar laser probe isochronal ages of 89—92 Ma and apparent ages of (46.6±6.4) Ma. The ages ranging from 97 to 46 Ma were reported for the first time in the isotopic dating researches of the Altyn Fault. The isochronal age group of (98—89) Ma indicates that a ductile strike-slip event, with low-grade metamorphism, began in late Cretaceous. This suggests that the strike-slip movement of the Altyn Fault should be related to the formation of the so-called west tectonic syntaxis in the Nepal-western Kunlun area. |
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Keywords: | Altyn Fault 40Ar/39Ar age strike-slip movement |
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