Abstract: Located in the western part of the Qaidam Basin, the Yingxiongling structural belt developed many Neogene oil and gas fields such as Shizigou, Huatugou, Youshashan and Yingdong, and so becomes the primary battlefield for oil exploration in the Qaidam Basin. In order to expand the exploration field of Neogene clastic lithologic reservoirs, comprehensive analysis has been carried out on outcrops, cores, particle size test and other data, and based on which two types of sandstones in shallow lake beach and underwater braided river delta were identified. On the background of lacustrine sedimentation, underwater braided river delta sandstone gradually accumulated into the lake basin under the control of western sources, and the NW-SE echelon-like shallow shoal lake beach sandstone migrated into the lake basin. The upper Ganchaigou underwater braided river delta sandstone is developed in the west of the structural belt, and the beach dam sandstone is developed in the west wing and the core of the structural belt. The lower Youshashan underwater braided river delta sandstone is developed in the west wing and the core of the structural belt, and the beach dam sandstone is developed in the east wing and the core of the structural belt. The structural evolution features indicate that the Neogene sandstone reservoirs in the upper Ganchaigou Formation and the lower Youshashan Formation were distributed in the slope area when they deposited, but today's Yingxiongling structural belt is the late inverse structure formed at the end of the Neogene Shizigou Formation. The sandstone deposited in the early stage might form lithologic traps like updipped pinchout and sandstone lens on the background of tectonic inversion. They are favorable exploration targets for finding large-scale lithologic reservoirs.

Key words: Qaidam Basin, Yingxiongling structural belt, Neogene, clastic rock, oil and gas exploration