THE ANALYSIS ON MIDDLE MIOCENE FORAMINIFERAL FAUNA OF THE TARIM BASIN AND THEIR ECOLOGY, PROPERTY OF STRATIGRAPHIC OIL—SOURCE POTENTIAL

The middle Miocene sequences in the Tarim Basin are characterized by the clastic deposits comprising mainly of sandstone,siltstone-mudstone and mudstone with the appearance of variegated zones interspaced with grey and greyish green and brownish and reddish brown.Foraminiferal materials sourced mainly from the Kashi Depression and the Kuche Depression,are attributed to the Anjuan Formation and the Jidike Formation.The ammonia fauna of the middle Miocene sequences widespread over the two near E-W striking belts,i.e the Kashi Depression from Wuqia to Xiao’atushi,and the Kuche Depression from Kuche river to Kuele respectively.The Foraminiferal fauna are associated with Cyprideis,littoralis,Cyprinotus deformis,Limnocythere orgulata,Cyclocypris sp.,Eucypris sp.,etc and in addition,specif ic fossils of charophytes.This fauna would survive in the environment of brackish-fresh transitional water,which is favourable for oil generation.