History of Neoproterozoic rift basins in South China: implications for Rodinia break-up

Abstract

Abstract We present here a first-order analysis of the Neoproterozoic continental rift basins in South China, focusing on the north-south trending Kangdian basin in the western part, and the Yangtze-side of the northeasterly-trending Nanhua basin. The Yangtze-side of the Nanhua basin is subdivided into the Hunan-Guangxi, the Jiangnan Ridge, and the northern Zhejiang sub-basins. The Neoproterozoic successions in these basins consist of four major sequence-sets, representing four phases of rifting. The first phase occurred at ca. 820 Ma after the 830–820 Ma bimodal magmatism and rapid crustal unroofing, and is represented by the Shiqiaopu Formation in the Hunan-Guangxi sub-basin and the Luojiamen Formation in the northern Zhejiang sub-basin. The second phase at ca. 800 Ma is represented by the Hongchicun Formation in the northern Zhejiang sub-basin. The third, a major rift phase, occurred at ca. 780–750 Ma, represented by the Sanmenjie Formation in the Hunan-Guangxi sub-basin, the Luokedong and Jingtan formations in the Jiangnan Ridge sub-basin, and the Shangshu Formation in the northern Zhejiang sub-basin. The final phase recorded the rift–drift transition during the Nantuo glaciation, estimated at ca. 750–690 Ma, with no volcanism. This was followed by a sag phase to the remainder of the Neoproterozoic, which saw the entire Yangtze Block covered with either platform carbonate deposits or basinal carbonaceous and cherty deposits. The basin history in South China prior to ca. 600 Ma can be well correlated with that in the Adelaide rift system in southeastern Australia, suggesting that South China could have been adjacent to eastern Australia in the supercontinent Rodinia, but broke away from Australia by the end of the continental rifting at ca. 750–690 Ma.