Biogeographic characteristics of Zhesi brachiopod fauna and reconstruction of tectonopaleogeography of Jiamusi-Mongolia Block

The Kungurian-Capitanian （Permian） Zhesi branchiopod fauna is mainly composed of cold-water typed taxa with high diversity and abundance. This fauna is similar with the coeval brachiopod faunas from Ti- man-Pechora, Svalbard, and Queen Elizabeth Islands of the Boreal Realm, with no real ＂warm-water＂ species. Zhesi brachiopod fauna is a cold-water fauna and should be assigned to the Boreal Realm. Considering the paleogeographic characteristics of this fauna and the basic rationale of paleobiogeographie provinces being controlled by latitude-temperate, and that the above areas were located at 50°N -70°N in the global paleoclimate reconstruction map compiled by Boucot et al. , the paleo-latitude of the southern margin of Jiamusi-Mongolia Block, where developed the Zhesi brachiopod fauna, is suggested ranging from 40°N to 60°N. Zhesi brachiopod fauna is an endemic fauna, containing more than 75% endemic species and self-grouped as a biogeographic province, termed Inner Mongolia Province. These characteristics indicate that this area was closed or semiclosed at that time. On the Jiamusi-Mongolia Block, the Herlen-Jiamusi Old-land as an obvious ＂continental barrier＂ hindered the northward migration of the Zhesi brachiopod fauna and the immigration of brachiopod species from other areas. The Tarim plate has collided with the Kazakhstan plate and the western part of South Tianshan-Beishan-Xar Moron Ocean has been closed. At the same time, the western margin of Jiamusi-Mongolia Block was joined with the Tarim plate. The Xar Moron Ocean in south of Jiamusi-Mongolia Block was wide e- nough and the ocean temperature rose gradually southward, so that it is not suitable for the cold-water brachiopods to survive and thrive on the northern margin of the North China plate. Thus, the ocean with large width and high temperature formed another natural barrier for the southward migration of the cold-water brachiopods.

Coevolution of brachiopod paleobiogeography and tectonopaleogeography during the late Paleozoic in Central Asia

Patterns of brachiopod paleobiogeographic regionalization in Central Asia reveal a coevolution between brachiopod paleobiogeography and tectonopaleogeography during the Early Devonian,Early Carboniferous,Late Carboniferous,Early Permian,and Middle Permian.The coevolutionary relationship reasonably accounts for the formation mechanisms of brachiopod paleobiogeography in this region,and also provides a basis for studies on the location and configuration of oceans and plates(blocks)during the late Paleozoic in Central Asia.