New understanding of tectonic characteristic of the Wensu salient in Tarim Basin

The Wensu salient locates in the northwestern margin of the Tarim Basin. It extends in NE-SW direction. Based on interpretation of the fault system in and around, as well as the regional geological structure characteristics, tectonic unit division and tectonic evolution, this paper points out that the formation and evolution of Wensu salient is mainly controlled by two major faults, i. e., the Gumubiezi fault and the Shajingzi fault. It was a paleo-uplift clamped by Wushi sag and Awati sag. Series secondary faults were developed in the Wensu salient, and divided it into Akesu low-bulge belt, Akeya fault-bulge belt, Gumubiezi fracture belt and Shajingzi transitional belt. The Wensu salient is featured by long-term uplift and short-term depression. During the Late Caledonian to Early Himalayan, influenced by the formation and re-activity of the two boundary faults, the Wensu salient upraised steadily, with simultaneous layer corrosion. During the Middle Himalayan Period, the Wensu salient was at its stable subsidence stage, deposited with the elastic rocks of Neogene Jidike Formation. During the Late Himalayan Period, a large nasal structure, i. e., lower eastern part and higher western part, was developed in the Wensu salient due to differential uplift. The former was deposited with Neogene Kangcun Formation and Kuqa Formation, while the latter was persistently corroded. When the two boundary faults finalized, the Wensu salient also finalized and formed the present tectonic features. It is concluded that the Wensu salient is a different tectonic unit from the Tabei uplift, and should be classified into the Kalpin fault-uplift. The Kalayuergun fault is the boundary between Tabei uplift and Kalpin fault-uplift, which are two of the first-order tectonic units of the Tarim Basin. This study is of great significance for guiding exploration and production in Wensu salient, and re-understanding the tectonic evolution and framework of the northwestern Tarim Basin.