Sedimentary Facies and Palaeogeography of the Evaporates in the Middle-Upper Yangtze Area
The evaporates as the cap rocks of the Early Paleozoic marine oil and gas accumulation occur on a wide range of scales and in tremendous thickness in the central-upper Yangtze area, and are assigned to the Longwangmiaoan and Maozhuangian-Zhangxian strata to the east of Chengdu in Sichuan, north of Zunyi in Guizhou and west of the Wuling Mountains in Hunan and Guizhou provinces. The features of tectonics, paleogeography and sedimentary facies are responsible for the restricted, enclosed or semi-enclosed tectonic-paleogeographic settings, and thus are favorable for the deposition of the evaporates in the study area.