Abstract:

This paper applies the method of seismic stratigraphy to divide the stra-tigraphic sequence of Qianjiang depression and to map the periodic fluctua-ting curves of the old lake level.The following results have been obtained:1.Two erosional surfaces has been discovered recently,one at the top ofthe Jingsha formation of Lower Tertiary,and the other at the top of the Yuyang formation of Cretaceous.The authors suggest that the explorationof oil and gas pools should be associated with these uncomformity planes.2.Among the horizons of Lower Tertiary—the lower and the upper partsof the 4th Member,the 3rd,2nd,and 1st Members in the Qianjiang forma-tion;the 4th,1st-3rd Members in the Jinghezheng formation—we have found the relation ship of onlap contacts.A new point has been suggested thatsome overlap unconformable stratigraphic oil and gas pools should be foundin the northern part of the Qianjiang depression.3.With correlation of periodic fluctuating curves of the lake level and the global Tertiary sea level,the Lower Tertiary in Qianjiang depression has been further divided in age.