Ili Basin is a Permo-Carboniferous basin that developed on Proterozoic basement with an area of 2.3?10

4

km

2

and the maximum thickness of 10000m and over.The Lower Carboniferous Aksak Formation is composed of clastic and carbonate rocks that deposited in shallow sea shelf and shallow sea platform environment

the source rocks of which are 200-700m thick.Organic carbon contents:limestone is 0.56%

mud-stone 0.99%;chloroform extract "A":the limestone is 32 ppm

the mudstone 92.8 ppm.The organic matter is mainly humic type and the ratio of vitrinite reflectance 1.99%-2.74%.The Upper Permian Timulik Formation is mainly clastic rocks of river and lacustrine facies

the source rocks of which is 80-100m thick.Organic carbon contents:mudstone-shale is 1.38%

limestone 0.65%;chloroform extract"A":mudstone-shale is 358 ppm

limestone 91 ppm.The organic matter is generally humic type and the ratio of vitrinite reflectance 0.75%.Light oil and bitumen showings have been found in two for-mations.The above mentioned two sets of source rocks occurred in Qapqal and K黱es Sags with extensive distrioution and great thickness.Besides

they have fine source-reservoir-cap rock assemblages and various trap types

thus the two sags are most potential in hy-drocarbon exploration.