PLATE TECTONICS AND BIOGEOGRAPHICAL REGIONALIZATION OF YUNNAN PROVINCE

On the basis of an integrated analysis of stratigraphic, paleontologic and paleomagnetic data,Yunnan Province may be tectonically divided into the Yangtze plate, Lancang plate and Baoshanplate. Among the three tectonic units, the types of biotas in the first two tectonic units are in themain identical, belonging to the Meridional biogeographical region; whereas in the last unit thereoccur Gondwanic deposits, which belong to the western Yunnan biogeographical region. Fromthe paleomagnetic data, in the Cambrian to Carboniferous the Yangtze plate was located in thesouthern hemisphere, and since the Permian it gradually drifted to the northern hemisphere. TheBaoshan and Lancang plates were both situated in te southern hemisphere in the Paleozoic andthen they migrated respectively into the northern hemisphere in theterminal Late Permian andTriassic. At last, in the Middle Jurassic the three plates collided and thus were an1algamated intoan entity.