Mid-Late Neoproterozoic rift-related volcanic rocks in China: Geological records of rifting and break-up of Rodinia
- 作者：Linqi Xia ; geologyx@pub.xaonline.com ; Zuchun Xia ; Xueyi Xu ; Xiangmin Li ; Zhongping Ma
- 关键词：Neoproterozoic ; Bimodal volcanism ; Continental rift ; Mantle plume ; Rodinia supercontinent ; China
- 刊名：Geoscience Frontiers
- 出版年：2012
- 期刊代码：pc98_16749871
- 类别：ear
- 出版时间：July, 2012
- 卷：3
- 期：4
- 页码：375-399
- 文件大小：6784 K
摘要
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聽Ma. On the basis of petrogeochemical data, the basic lavas can be classified into two major magma types: HT (Ti/Y聽>聽500) and LT (Ti/Y聽<聽500) that can be further divided into HT1 (Nb/La聽>聽0.85) and HT2 (Nb/La聽鈮ぢ?.85), and LT1 (Nb/La聽>聽0.85) and LT2 (Nb/La聽鈮ぢ?.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 Mid-Neoproterozoic聽and Early Cambrian coincided temporally with the separation between Australia-East Antarctica, South China and Laurentia and between Australia and Tarim, respectively. The聽Mid-Late Neoproterozoic volcanism in China is the geologic record of the rifting and break-up of the supercontinent Rodinia.