Abstract:
The Zhenzhushan Group consists of a suite of Mesoproterozoic Jixianian metamorphosed abyssal turbidite and volcanic rocks in the eastern segment of the convergence zone between the Yangtze plate and the Cathaysian plate in the Wuyuan-Leping areas, northern Jiangxi. From below upward it can be further divided into the Fuzikeng Formation, Zhangshan Formation, Zhouxi Formation and Zhongzhou Formation. Volcanism shows the trend of evolutions from weak to strong and again to weak. The petrochemical characteristics suggest that the tectonic environment belongs to the volcanic island arc or active marginal basin and that the group is stratigraphically equivalent to the Xiushui Formation of the Shuangqiaoshan Group and the Xikou Group in a back-arc basin, the Zhujia Group, Tongchang Group-complex and Zhangcun Group-complex in an inter-arc basin and the Shuangxiwu Group in a volcanic island arc, but they differ greatly in rock association. They are synchronous but heteropic products. They combine to form a double-island arc orogenic belt model on the Yangtze continental margin. It is the result of subduction-collisional orogeny of the Cathaysian plate and Yangtze plate at the end of the Mesoproterozoic. The establishment of the Zhenzhushan Group provides new evidence for Mesoproterozoic plate collision in South China.