泌阳断陷湖盆陆相层序划分及其沉积体系配置

Terrigenous Sequences and Depositional System Configuration in Fault-depressed Biyang Lacustrine Basin

泌阳断陷历经中生代小型拉分盆地、早第三纪断陷盆地和晚第三纪坳陷盆地等三个盆地原型的演化、叠合过程，形成了三个盆地充填序列及其所对应的三个构造层序，其界面皆为区域性构造不整合面；沉积总体样式分别为冲积扇—洪水漫湖沉积体系组合、冲积扇—扇三角洲—湖泊—三角洲沉积体系组合、冲积平原—砂泥坪滨浅湖沉积体系组合。泌阳断陷湖盆沉积充填主体为构造层序Ⅱ（即下第三系），共可划分为七个地震层序，各地震层序具有特定的沉积体系配置关系。作为泌阳断陷油气勘探主要目的层段的下第三系核桃园组可进一步划分为十二个层序，其界面或为沉积相不连续面，或为沉积相转换面，少数为陆上侵蚀面或沉积间断面。其中，核三上段包括跨时分别为１．０８Ｍａ、１．４０Ｍａ、１．０２Ｍａ的三个层序，由南往北呈现冲积扇—扇三角洲—湖泊—三角洲的沉积体系空间配置。泌阳断陷陆相层序的体系域具四分性，一个典型的特定体系域有其特征性的小层序组堆叠型式，并具有特征性的沉积相配置。

Biyang fault-depression experienced three evolutional phases: pullapart during Mesozoic, rift during Paleogene, and downwarping in Neogene. Accordingly, three basinfill sequences and corresponding tectonic sequences have developed. These sequences are defined by regional unconformities, with their general sedimentary style being respectively assemblage of fluvial fan-floodlake depositional systems, fluvial fan  fan delta  lacustrine  delta depositional systems, and fluvial plain  sandmud flat  coastalshallow lacustrine depositional systems. Tectonic sequence II ( Eogene) comprises the main sedimentary fill of the basin and can be divided into seven seismic sequences, each of which exhibits specific depositional system configuration. The Hetaoyuan Formation (Eh), a major target of petroleum exploration in the basin, can be further divided into twelve sequences, whose boundaries are mainly discontinuous or transformed facies interfaces, or in minor cases are subaerial erosion surfaces or depositional hiatus. 