摘要
结合山东惠民盆地中央隆起带古近系沙河街组第三段 (简称沙三段 )层序地层学研究 ,根据层序中湖平面变化特点和相应的沉积物特征 ,提出了陆相湖盆中层序内体系域的四分法 ,一个完整的层序由低位、湖侵、高位和下降四个体系域组成 ,并且层序界面位于湖平面最大下降的位置 ,介于下降域和低位域之间。层序地层中存在四个关键性界面 :首泛面、最大湖泛面、始降面和最大下降面 ,其中首泛面对应于湖水由相对稳定到快速上升时的初始湖泛面 ,为低位域与湖侵域间的分界面 ;最大湖泛面对应于湖水快速上涨至最大限度时的湖泛面 ,为湖侵域与高位域间的分界面 ,在界面附近多形成特征的CS段 ;始降面对应于湖平面开始快速下降时的沉积界面 ,为高位域与下降域的分界面 ;最大下降面也是层序界面 ,为湖盆水体快速下降或湖盆岸线快速退到最低点时的沉积界面。结合研究区的岩芯、录井、测井、地震等资料综合分析 ,本文总结了四个关键界面的识别标志。中央隆起带沙三段沉积共划分出六个体系域 ,分属三个层序。本文以层序II沉积为例 ,阐述了不同体系域的沉积体系特征 ,低位期湖盆水域面积小 ,河流—三角洲沉积体系发育 ,河流流经距离长 ,边缘地区形成下切谷 ;湖侵期发育小规模的退积式三角洲沉积 ,砂体较不发育 ;高位期湖盆水?
The sequence stratigraphy studies of the Member 3 of Shahejie Formation(SHA-3)in the western of Huimin Basin, Shandong Province indicates that it is more suitable to divide a sequence into four system tracts in the lacustrine basin including lowstand system tract(LST), lake-transgressive system tract(TST), highstand system tract(HST) and falling-stage system tract(FSST). According to characteristics of lake level change and its corresponding sediments, the sequence boundary is located between the LST and FSST. There are four key surfaces in a sequence: first flooding surface, maximal flooding surface, first falling surface and maximal falling surface. The first flooding surface is located between the LST and TST, and is corresponded to the sedimentary boundary while the lake water changes from relatively stable stage to quickly rising stage. The maximal flooding surface is located between the TST and HST, and condensation section (CS) usually forms near the surface. The first falling surface is located between the HST and FSST, and is corresponded to the sediment boundary while the lake level begins quickly falling. The maximal falling surface is also the sequence boundary, and is corresponded to the sediment boundary while the lake level falls quickly to the lowest location. This paper has summed up identical marks on the cores, well loggings, seismic data and so on. The SHA-3 Member of central uplift belt can be divided into six system tracts and three sequences. The distribution characteristics of the different system tract are discussed in Sequence II. During The SLST the area of lake water is small, and river-delta deposition system develops, and the river is usually very long, and invised valleys also develop at margin region of the lake basin. The STST develops some small regressive deltas, and sandbodies are less. During the HST the area of lake water is large, main sandbody is some deep-water turbidity sands. The FSST develops abundant transgressive deltas. So sandbody develops well during the FSST and LST, and oil rocks form most during the TST and HST.
出处
《古地理学报》
CAS
CSCD
2002年第3期40-46,共7页
Journal of Palaeogeography：Chinese Edition
基金
惠民凹陷中央隆起西部沙三
四段沉积体系
储层展布及油气预测研究 (获 2 0 0 0年山东省科技进步二等奖 )项目资助
