Junggar is a huge faulted basin and is covered by sedimentary rocks constituting about 130000km

2

.The Middle and Upper Carboniferous

the Permian

and the complete Meso-Cenozoic sediments are developed on the Variscian folded basement.The Middle and Upper Carboniferous are marine

transitional and continental deposits.The Permian belong to continental deposits.Both of them are multi-depocenter clastic rocks with abundant organic matters.According to the main geochmical indexes of petroleum generation

they should be the main source rocks in this basin.During Meso-Cenozoic

the southern part of the basin developed into deep depression

while the northern part gradually became a southtilting slope.So it is most favorable to the Permo-Carboniferous hydrocarbons to migrate and accumulate toward the northern marginal zone

in which the prospecting for oil would be more effective.