Evolution of the Neoproterozoic rift basins and its implication for oil and gas exploration in the Tarim Basin

Abstract

According to the aeromagnetic, seismic, and geological data, the surface structure, sedimentation, and distribution characteristics as well as the deep dynamic mechanism of the north-south differentiated Neoproterozoic rift basins were well investigated to reveal the tectonic evolution and its control on the distribution of the Early Cambrian sedimentary basin and source rocks in the Tarim Basin. The rift basin in the southern Tarim was a product of superplume activities during the early breakup period of the Rodinia supercontinent. It initiated in the Early Cryogenian (about 780 Ma) and appeared as NE-direction aulacogens extending into the Tarim Basin. The rift basin in the northern Tarim was a back-arc rift basin derived from the subduction of Pan-Rodinian oceanic plate, which initiated in the Late Cryogenian (about 740 Ma) and occurred as a nearly EW-direction narrow band across the Tarim Basin. The northern Tarim back-arc rift basin had similar formation and evolution process to the Late Mesozoic-Cenozoic back-arc rift basins in East Asia, both showing an oceanward migration; however, the Tarim rift basin finally evolved from the fault-depression basins into passive continental margin. The Neoproterozoic rift basins controlled not only the distribution of source rocks in the syn-rift period but also the development of Early Cambrian sedimentary basin. Nearly EW-distributed syn-rift (Cryogenian to Ediacaran) and post-rift (Lower Cambrian Yurtusi period) source rocks were likely to develop between the present Tabei uplift and central uplift belt.