The petroleum geological conditions are very complex in the northern margin of the Junggar basin

imposing great challenges to petroleum exploration.Based on the research of the tectonic attribute

stratigraphic distribution and exploration potential of the basin recently

it is concluded that the sedimentary environment in the Early Permian was an semi-enclosed remnant sea that was formed on the background of rifting and extensional tectonics movements and associa-ted with volcanic activity

providing favorable conditions for the deposition of high-quality source rocks.Influenced by the tectonic movements of the Late Hercynian and Indosinian

the Hashan thrusted towards to the basin

resulting in the superimposition of multi-phase thrust nappes in the Lower Permian and extensive uplifting and erosion of the Upper Per-mian.As a result

the present boundary of the basin is significantly smaller than that of the depositional period.The structure interpretation model of thrust nappe and later strike-slip of Hala'alt is established with the technology of fault-fold structural analysis.Source rocks of the Fengcheng Formation are identified in the Hala'alt nappe structure belt.And it is believed that the source rocks can extend northward to the Daerbute fault

enlarging the distribution area of source rocks by 1 000 km

2

.The source rocks have high organic content and moderate thermal maturity

and their oil-source correlation reveals that the oil in the Cretaceous

Jurassic

Permian and Carboniferous all are derived from this set of source rocks.The identification of this source sequence underlying the Lower Permain thrust nappe enlarges the area of exploration and even is of great significance for hydrocarbon exploration in the whole northern Junggar Basin.