Continental tholeiitic basalt of the Akesu area (NW China) and its implication for the Neoproterozoic rifting in the northern Tarim
塔里木西北缘阿克苏地区大陆拉斑玄武岩对新元古代裂解事件的制约

In northwestern Tarim, Neoproterozoic Sugetbrak Formation unconformably overlies the Akesu Precambrian blueschist and intruding mafic dike swarms. Two Layers of basalt are intercalated in the lower part of the Sugetbrak Formation, their age and tectonic setting are important for the understanding of Precambrian tectonics of the Tarim, and related supercontinent evolution as well as the geodynamics. This study presents our new data of whole-rock geochemistry and zircon U-Pb dating from two basaltic interlayers. The results reveal that all analyzed samples belong to continental tholeiitic basalt showing trace element features similar to that of the typical continental flood basalt, they were derived from an enriched mantle source and suffered variable crustal contamination. The LA-ICPMS U-Pb dating on the zircons from the basalts yielded ages ranging from 1945Ma to 755Ma, indicating that these zircons were inherited from the crustal materials during the ascending of the basaltic magma, the age of the basalt is therefore considered to be younger than 755Ma. These results suggest that the tholeiitic basalts formed in an intraplate rifting setting probably resulted from a mantle plume beneath the Rodinia supercontinent, the tholeiitic basalt is a line of evidence for the Neoproterozoic rifting of the Tarim from the Rodinia supercontinent.