Abstract: The crust in Junggar basin can be divided into the upper, middle and lower ones from the bottom of sediments to the Moho. The middle crust is thinner than the upper and the lower. The basement of the basin is formed by two parts: the folded basement and the crystalline one. The upper basement is composed of the Upper Paleozoic. In the southern basin, the folded basement is thinner or absent, with four structural lines of NW, NE, SN and EW trends. The NW and NE lines control the SN zonation in Class-II tectonic elements; the SN and EW lines are blind ones. The basement of hinterland in Junggar basin is composed of a series of blocks with the EW and SN lines crossing each other, and the secondary swells are formed at the apical corners. Two groups of faults with NE and NW trends exist in the northwestern margin, generating some small blocks like "H" shape. In the Indo-Chinese epoch, the NWW and NE faults crossing each other in eastern Junggar basin shaped the structure of "# Type" because of the clockwise distorting of the basement. In the southern margin of it there exists one SN structural line or belt for about per half degree from 84°E to 91°E. These longitudinal belts have the properties of low density, medium-low resistivity and low velocity, and can be as the buffer zones, which take important controlling parts in sedimentary facies change, tectonic migration and hydrocarbon accumulation here.

Key words: Junggar basin, crust, basement, NS structure, buffer zone