Abstract:

Turpan-Hami basin is one of the three biggest oil and petroleum sources in XinJiang Province, which is the first Jurassic coal measures-related oil basin in China. The sedimentary systems of Mid-Lower Jurassic in Turpan depression were rerecognized through the analyses of outcrop sections, cores and loggings to direct the prospecting for oil-gas effectively. The result shows that there are also meandering river-meandering delta-lacustrine systems except for braided river-braided delta-lacustrine and alluvial fan-fan delta-lacustrine sedimentary systems which have been realized before. On the basis of research on depositional evolution in time and distribution in space, it suggests that in Turpan depression braided river-braided river delta systems were common in Badaowan Formation, meandering river-meandering delta systems are predominant upward in Xishanyao and Sanjianfang formations, and the lacuatrine facies are widespread developed to the top of the research strata in Qiketai Formation, which shows an obviously retrogradational sequence. There were great differences between south and north of the depressions. On the south, it is characteristic as braided and meandering deltas, while on the north it is characteristic as braided delta and fan delta. Finally, a sedimentary model is constructed for the Mid-Lower Jurassic in Turpan depression.

Key words: sedimentary system, sedimentary model, Mid-Lower Jurassic, Turpan depression