Xiaokuzibai Fm

Kuqa Depression, NW Tarim. Named by the Eighth Geological Party of the Xinjiang Bureau of Geology and the Potash Party of the former Institute of Geology and Mineral Deposits, Chinese Academy of Geological Sciences in 1978. Upper formation in the Kumugeliemu Gr. This formation is equivalent to the “Red Rock Series” defined by the Sino-Soviet Thirteenth Airborne Magnetic Survey Party (1952–1953) and the “Mudstone Formation” and “Mudstone-Siltstone Formation” in the upper part of the “Talak Group” defined by the Second Geological Party of the Xinjiang Bureau of Geology (1963). The naming section is located in the vicinity of Xiaokuzibai in the northern part of Baozidong Township, Wensu County north of Aksu City, Xinjiang.

Synonym: Xiao Kuzibai Fm

Primarily lagoonal fine clastic rocks or evaporite, characterized by the presence of gypsum-bearing strata; lithologically purplish red, thin-bedded, calcareous mudstone, siltstone and fine sandstone with gypsum rock. The thickness is approximately 1000 m.

The formation contains small quantities of fossils. The sporopollen is Interporopollenites, Platycaryapollenites, Trudopollis, Pentapollenites, etc. This sporopollen assemblage is similar to that in the Eocene Honggou Formation in the Xining-Minhe basin of Qinghai in the aspects. Additionally, there are also the ostracods ? Loxoconcha sp. and Sinocypris sp., the gastropods ? Newtoniella sp. and Potamides sp. and the bivalves Corbula sp. and ? Anisocardia sp.

It is interpreted as lagoonal fine clastic rocks or evaporates.