潜江凹陷地震层序划分、湖平面升降问题初探

潜江凹陷位于江汉盆地中部,其构造位置如图1所示.1958年以来,地质部、石油部和有关院校作了大量的物探、钻探和地质研究工作.初步查明凹陷在中、古生代灰岩的基底上沉积了上万米的白垩—第三系陆相地层,并在下第三系中发现了潜江组和新沟咀组两个主要石油勘探目的层,找到了若干油田.本文的目的在于用地震地层学的方法,重新认识原有的某些结论,提出一些新的看法,供交流、讨论.

ON THE SEISMIC STRATIGRAPHIC SEQUENCE,LAKE LEVEL FLUCTUATION AND OIL PROSPECTING IN QIANJIANG DEPRESSION

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.