Xingouzui Fm

Jianghan Basin - SE. The naming section is located in a well at Qianjiang County, Hubei. Named by the Jianghan Petroleum Exploration Division in 1963 and formally used in the “Regional Stratigraphic Table of the South-central Region”.

A sequence of gray or red mudstone, marlstone and sandstone, with lacustrine deposits such as gypsiferous mudstone and salts. The formation may be divided into two members: Lower member, alternating beds of dark gray and grayish black mudstone and grayish white and light brown sandstone, with gypsiferous mudstone or gypsum; Upper member, mainly dark gray, brown and purple mudstone and gypsum-bearing mudstone with sandstone and marlstone. The thickness is generally 500–700 m and locally may exceeds 1000 m.

There are abundant fossils in the formation. The fishes are mainly Tungtingichthys sp.; the ostracods are represented by the assemblage of Limnocythere, Sinocypris and Eucypris; the charophytes mainly include Peckichara varians, Grovesichara changzhouensis, Obtusochara elliptica and Gobichara tenera. The sporopollen assemblage is dominated by angiosperms, with a low content of gymnosperms and <10% of pteridophytes. The formation commonly contains Extratriporopollenites and Ephedripites, in addition to certain amounts of Ulmus and Quercus.