Deep structure and lithospheric shear faults in the East Kunlun-Qiangtang region,northern Tibetan Plateau |
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| Authors: | Xu Zhiqin Yang Jingsui Jiang Mei Li Haibing Xue Guangqi Yuan Xuecheng Qian Hui |
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| Institution: | (1) Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China;(2) Institute of Geology, Chinese Academy of Sciences, 100029 Beijing, China;(3) Department of Geology, Taiwan University, 106-17 Taibei |
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| Abstract: | The Cenozoic magmatic rocks of shoshonitic series in the eastern Qinghai-Tibet Plateau include potassic alkaline plutonic
rocks, volcanic rocks, lamprophyres and acidic porphyries. Analytical results show that these different lithological rocks
are extremely similar in Sr, Nd and Pb isotopic compositions with the range of 0.705 187– 0.707 254 for87Sr/86Sr, 0.512 305–0.512 630 for143Nd/144Nd, 18.53–18.97 for206Pb/204Pb, 15.51–15.72 for207Pb/204Pb and 38.38–39.24 for208Pb/204Pb. They are isotopically similar to the EMII end-member. This indicates that mantle metasomatism must have taken place in
their source region. The formation of these particular rocks is related to crustal thinning and mantle upwelling in a large-scale
strike-slip and pull-apart fault zone at about 40 Ma in northern and eastern Qinghai-Tibet Plateau |
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| Keywords: | isotopic characteristics magmatic rocks shoshonitic series eastern Qinghai-Tibet Plateau |
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