The turbidity sediments are delt with here in the 4th and 5th members of the Miocene Pakabulak Formation in Kekeya Oilfield in Tarim Basin.They are composed of rhythmic sequence of sandstone and mudstone with low mineral and structural maturity.The probability curve of particle size is a smooth one with gentle slope

indicating that the sediments are transported in suspension.The A-D

A-C and A-B intervals of Bouma sequence are of ten seen in these turbidity sediments

without remarkable evidence of sliding.There-fore

they were presumably deposited on the steep flank of the lacustrine ba-sin rapidly in case of diluvial.The index ρ(proximity to erosion area)isabout 70-80%

this fanhead feature proves again a lacustrine turbidite quite close to erosion area.The major reservoir of this oilfield is closely related to turbidity sand bo-dies.The porosity of the reservoir in its western part

being near the erosion area

is poor

but it gets obviously better between the fanhead and its middle part

where most of wells with high productivity are actually located.It seems that Mt.Kunlung was obviously uplifted when the Pakabulak Formation was forming.This heralds that turbidity sediments similar to those found in Kekeya Oilfield could be expected in the Yiliyas and Heshilafu region of Shaehe County

Fusha regions of Yecheng County and Duwa region of Pishan County.