Permian Paleogeography of the Eastern CAOB: Paleomagnetic Constraints From Volcanic Rocks in Central Eastern Inner Mongolia, NE China

We carried out a paleomagnetic investigation on Permian volcanic rocks from central eastern Inner Mongolia, NE China, in order to identify the paleoposition of the North China and Songliao-Xilinhot blocks during Permo-Carboniferous times and thereby define the spatial-temporal history of the eastern Paleo-Asian Ocean (PAO). Two prefolding magnetization components were isolated from the Sanmianjing and Elitu Formations (283-266Ma) along the northern margin of North China block (NMNCB) and the Dashizhai Formation (280Ma) in the Songliao-Xilinhot block (SXB). These two results suggest paleolatitudes of 4.9 degrees N for the SXB and 22.3 degrees N for the NMNCB. Previously published results are classified according to recently proposed models and evaluated for the influence of inclination shallowing. Combined with earlier multidisciplinary studies, we propose a tentative paleogeographic reconstruction model for the eastern Central Asian Orogenic Belt (CAOB) during the Late Carboniferous to Early Triassic times. Siberia was situated at middle-high paleolatitudes (45 degrees-65 degrees N), and the Central Mongolia-Erguna and South Mongolia-Xing'an blocks had a middle latitude (30 degrees-45 degrees N) from the Late Carboniferous to Early Permian. By the Late Permian to Early Triassic (250Ma), there was no significant latitudinal difference between the eastern CAOB blocks. Final closure of the eastern PAO along both the Hegenshan-Heihe and Solonker sutures took place followed by the formation of Cinamuria.