Abstract:

In this paper,the writers point out that the development of stratigraphy and the tectonic characteristics of the Kashi subdepression,Yecheng subdepression and Maikaiti slope of southwestern depression of Tarim basin are controlled by the compressive and compresso-shaer stresses exerted from Tianshan and Kulun Mts.Secondary petroleum traps as Kekeya oilfield in Kashi and Yecheng subdepressions may be found in Neogene which measures 8,000—10,000mthick and various subtle faults developed below it are favourable in the forming of these traps.After a comprehensive study,the authors proposed that structures in the 2nd row from south of the Yecheng and Kashi subdepressions and Mai-kaiti Slope are more promising in petroleum prospecting.The Kuqa depression is formed mainly by Mesozoic differential block fault-ing and is filled with a series of coal seams and petroleum-generation source rocks.The Cenozoic compressive stress exerted from Tianshan Mt.gave rise to varietyof tectonic features and discordance between Mesozoic and Cenozoic groups.Because of the absence of good Cenozoic source rock and the existence of unpermeable salt rocks at the bottom of it,the exploration work should mainly be carried out in the north of Changmzituk fault within areas where Mesozoic rocks are well developed.Structures within the 2nd and 3rd rows from north and the footwall of the huge nappe of North Bygulu in the northern margin of this depression are also prospecting.Geologically the research level of east Tarim basin is rather low,but it has a broad area and its source rock of Triasic-Jurasic is believed thicker than the previous depressions,therefore,it would be proved abundant in oil and gas.