Tectonic evolution of the Junggar foreland basin in the late carboniferous-permian

A comprehensive study has been carried out to subdivide and correlate the U pper Carboniferous and Permian sedimentary successions in the Junggar basin based on outcrops and drilling and geophysical data. The study results, co mbined with geological analyses of the basin's periphery and the basement, as well as studies of the sedimentary rocks within the basin, the unconform ities, tectonic geometry, kinematics and geodynamics, lead to the conclusio n that the Jung-gar basin was characterized by the development of foreland basin systems during the Late Carboniferous and Permian. During that period , three foreland basin systems were developed: (1) the northwest foreland b asin system, which trended nearly north-south from Mahu to the Chepaizi Pal aeo-mountain during its early stage of development and thus it was also ref erred to as the west foreland basin system; (2) the Karamaili foreland basi n system in the east and (3) the,Northern Tianshan foreland basin system in the south. These systems are different in size, development stage and time of formation. The first two are developed earlier than the third, but they are smaller in size. All the structures in the Junggar basin have resulted from the integration and superposition of structural elements in the above three systems. In general, the development of the Junggar basin can be div ided into four stages. Stage I was marked by the creation and evolution of the marginal western foreland and the peripheral Karamaili foreland basin s ystems during the Late Carboniferous-early Early Permian (C-3-P(1)ja). Stag e II was characterized by the development of complicated foreland basin sys tems during the middle-late Early Permian (P(1)jb-P(1)f) when the three for eland basin systems took their shapes. Stage III was the integration stage of peripheral foreland basin, systems during the Middle Permian (P-2) in wh ich steady and slow tectonic subsidence prevailed. Stage TV coincided with the shrinking of foreland basin development during the Late Permian (P-3).