The salt rock genesis of 3^rd member of Shahejie formation in Dongpu Depression and the division of saline formation sequence

In 3^rd member of Shahejie formation in Dongpu Depression, deep grey and dark mud stone and a few gravity sand bodies developed in the highstand, and in the lowstand, salt rock, gypsum rock, lowstand deltas and fan deltas developed, as a result, deep lake mudstone are interbeded with evaporite and lowstand sand bodies. According to the core data, the characteristic of salt sedimentation., palaeoclimate and palaeoenvironments, salt rock is thought to be deposited in shallow water. The black mudstone deposited in deep water interbedded with salt deposited in shallow water shows that the lake level changes frequently during the sedimentation of 3^rd member of Shahejie formation. With the method of parasequences identification based on the the characteristic of salt cadence, the sequence division is accord with the practice in saline formation in Dongpu Depression.