Mid-Late Neoproterozoic China： Geological records Rodinia rift-related volcanic rocks in of rifting and break-up of |
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| Authors: | Linqi Xia Zuchun Xia Xueyi Xu Xiangmin Li Zhongping Ma |
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| Institution: | Linqi Xia*,Zuchun Xia,Xueyi Xu,Xiangmin Li,Zhongping Ma Xi’an Institute of Geology and Mineral Resources,China Geological Survey,Xi’an,Shaanxi 710054,China |
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| Abstract: | Early Cambrian and Mid-Late Neoproterozoic volcanic rocks in China are widespread on several Precambrian continental blocks,which had aggregated to form part of the Rodinia supercontinent by ca.900 Ma.On the basis of petrogeochemical data,the basic lavas can be classified into two major magma types:HT(Ti/Y>500) and LT(Ti/Y<500) that can be further divided into HT1 (Nb/La>0.85) and HT2(Nb/La≤0.85),and LT1(Nb/La>0.85) and LT2(Nb/La≤0.85) subtypes, respectively.The geochemical variation of the HT2 and LT2 lavas can be accounted for by lithospheric contamination of asthenosphere-(or plume-) derived magmas,whereas the parental magmas of the HT1 and LT1 lavas did not undergo,during their ascent,pronounced lithospheric contamination.These volcanics exhibit at least three characteristics:(1) most have a compositional bimodality;(2) they were formed in an intracontinental rift setting;and(3) they are genetically linked with mantle plumes or a mantle surperplume.This rift-related volcanism at end of the MidNeoproterozoic and Early Cambrian coincided temporally with the separation between AustraliaEast Antarctica,South China and Laurentia and between Australia and Tarim,respectively. The Mid—Late Neoproterozoic volcanism in China is the geologic record of the rifting and break-up of the supercontinent Rodinia. |
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| Keywords: | Neoproterozoic Bimodal volcanism Continental rift Mantle plume Rodinia supercontinent China |
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