Abstract: The comparison of structural conditions in western and eastem basins of China and geochemical analysis of Lower Cretaceous source rocks ill Junggar basin are nade. It is considered thal in tlre easten basins there exist vast distributions of Cretaceous source rocks, better reservoir qualty and thickness than those of the western basins 01 the whole,but the structural and depositional conditions in foothill sag in North Tianshan Mountain of Junggar basin are of a certain similarity with those in the eastern basins. ie, its Lower Cretaceous strata possesses a capability of lhydrocarhol generation, being significant and really existing source rocks for petroleum exploration of southern margin of Junggar basin. The oil-source rock correlation indicales that the crude biomarker features from Tugului and Horgos areas arc similar to thosc from surtacc crude and asphalt in Qingshuihe arca, and these bromarkers were all coming from the source rock of Lower Crelaceous. Therefore. the Cretaceous source rock can be determined reliably. In this paper, the distributiol extension of reservoir with oil source of Cretaceous is delineated. 'The contribntion of the Cretaceous source rock to hydrocarbon accumulation in foothill thrust zone is pointed out, and the mnajor target areas and drilling horizons for oil exploration are suggested in this paper. It is expected that lhte domain of petroleum prospecting in southern Junggar 's foreland basin will be wider and wider.

Key words: Junggar basin, Cretaceous, geochemistry, oil source corelation