PLATE TECTONIC PROBLEMS OF THE INNER MONGOLIA XINGAN REGIONS
Zhu Rufeng(2nd. Regional Geological Survey Team, Inner Mongolia Bureau of Geology and Mineral)
Through synthetically studying of lithofacies, fossil community, petrochemistry of volcanic rocks and paleomagaetism of early Permian, the writer has thought the Inner Mongolia Xingan subdomain to belong to active continental margin in early Permian, The contact between Tethys warm water type of living things and Arctic cold water type of ones was separated by existed deep sea.In early stage of early Permian, a volcanic are extended along Wulanhot-Lindong-Linxi areas. It controlled distribution of sediments and biocoenosis. In a-rc front area, Corals-Brachiopods-Bryozora community lived; Close to arc, Fusulinds-Brachiopods-Mollusca community; Volcanic arc, Brachiopods-community and in arc-rear area, Brachiopods-Mullusca community. Paleotopography subdomain dropped from west to east.Late stage of early Permian, east part of the subdomain speedly uplifted. The sediments are represented by marine with continental intercalations, while west part is marine basin exposition. East of the subdomain is higher than west in paleotopo-graphy. Moreover, based on the intermingling of planktons and benthoses in different time, three tectonic stages are determined as following; Hugeterian is separating stege of oceans Zhesian is junction stage of plate; Yihewusurian to early Triassic period is collision stage of plate.