Brachiopod Faunas from the Permian Jisu Honguer (Zhesi) Formation in Xilinhot, Inner Mongolia, and its significance

Lots of brachiopods (mainly consisting of Productidina and Spiriferidina) which include 22 genera and 42 species were discovered in Jisu Honguer (Zhesi) Formation, Howl Shu section, Hexigten Banner, Inner Mongolia. They show typical Zhesi fauna characteristics. Brachiopod biostratigraphic correlations with adjacent areas show that this brachiopod fauna should belong to Middle Permian Wordian period. There are 10 genera and 26 species of cold-water type elements in Zhesi fauna, which account for 61.9% of the total species, and only 1 species of warm-water element, which accounts for 2.4%, showing typical cool-water type fauna characteristics and belonging to the Boreal Realm. Furthermore, the grain combination of carbonate in Jisu Honguer (Zhesi) Formation belongs to Bryozoan-Echinoderm-Brachiopod assemblage, representing the cool water sedimentary environment, and this also confirms the cool-water characteristics of Zhesi fauna.