干旱区生态环境知识资源中心

Nine fossil bivalve assemblages have been recognized in the Hohxil desert area of western Qinghai, China: Wuchiapingian Netschajewia jiangsuensis assemblage, Smithian - Spathian Bakevellia costata - Leptochondria virgalensis - Entolium microtis assemblage, Carnian Halobia austriaca - Halobia yunnanensis - Halobia convexa assemblage, Norian Halobia yandongensis - Halobia aff. dilatata assemblage, Carnian-Norian Trigonodus carniolicus - Unionites? rhomboidalis assemblage, Bathonian Kimmeridgian Radulopecten pamirensis - Protocardia stricklandi assemblage, Late Jurassic Pseudolimea - Opis assemblage, Early Cretaceous Eokoreanaia qinghaiensis assemblage, and Miocene Sphaerium nitidum assemblage.

The marine bivalves, except for the cosmopolitan Halobia, are Tethyan and characterised mainly the northern margin of the Tethys. Non-marine taxa are restricted Asian forms. These assemblages are very significant in studying the biostratigraphy, paleobiogeography and tectonic history of the Qinghai - Xizang Plateau. In the Early Cretaceous marine connections were broken and the area has experienced since then only terrestrial conditions.