断陷湖盆陡坡带陆相层序界面模式新论──以泌阳断陷双河-赵凹地区下第三系核三~上段为例

On Terrigenous Sequence Boundary Model of the Steep Slope Zone in Fault-depressed Lacustrine Basin

由于断陷湖盆陡坡带古地形上不存在从平缓到陡峻的突然坡折，其沉积滨线坡折难以识别。本文拟就将特定井的位置作为参照物，来划分陆相层序及其体系域。文中采用泌207井作为参照井的结果显示，研究区核三上段所划三个层序发育Ⅰ型层序界面一个、Ⅱ型层序界面三个。按“体系域具四分性”论点，发育齐全的四个体系域具五个界面，除顶、底界面归属层序界面之外，其它三个界面皆为体系域界面。小层序界面是一次次小规模的洪泛作用的记录，从盆缘至盆内表现为洪泛面及可与之对比的相当界面，洪泛面属沉积微相转换面。

Because in the steep slope zone of fault-depressed lacustrine basin there is no sudden break which paleaotopography appears from gentle to steep, the depositional shoreline break is difficult to recognize. It has been put forward that the position of specific well is taken as reference to divide terrigenous sequence and system tract. The research result by using B207 as reference well shows that the three sequences of the upper member of Eh3 in researching area have 1 sequence boundary of type Ⅰ and 3 sequence boundaries of type Ⅱ. According to the thesis of four-division of system tract, a complete terrigenous sequence can be divided 4 system tracts and has 5 boundaries, of which the top and bottom belong to sequence boundary, and other 3 to system tract boundary, Parasequence boundary is a record of flooding in minor scale, and presents a flooding surface which is a transformation interface of sedimentary microfacies and the boundary which is equivalent to flooding surface.