陆相断陷盆地湖平面变化曲线与层序地层学框架模式讨论  

THE CURVE OF LACUSTRINE LEVEL CHANGE IN CONTINENTAL RIFT-SUBSIDENCE BASIN AND THE SEQUENCE STRATIGRAPHY FRAMEWORK MODEL

作　　者：郭建华[1] 朱美衡[1] 刘辰生[1] 王明艳[1] 

机构地区：[1]中南大学地学与环境工程学院,湖南长沙410083

出　　处：《矿物岩石》2005年第2期87-92,共6页Mineralogy and Petrology

基　　金：湖北省教育厅自然科学基金(项目编号:2000A51007);中国石油与天然气总公司中青年创新基金(项目编号:99-07)资助

摘　　要：　陆相断陷盆地形成于控凹断层长期稳定的下沉过程中,因此,湖平面的升降变化主要是受控凹断层的活动速率与活动特点、海侵及气候的控制。由于控凹断层活动的幕式性与阶段性,以及突发的海侵事件,导致湖平面升降变化轨迹为两段折线式,即快速的湖侵与缓慢的湖退。在一个湖平面升降旋回过程中,形成了下部的湖侵体系域和上部的湖退体系域,可称之为T-R旋回沉积层序。层序的边界可能是由于幕式性的构造活动所反映出的局部的沉积间断与缺失,或者是由于突发性的海侵而造成的"沉没"。很显然,这种T-R旋回层序地层学格架模式缺乏大面积的暴露而形成的型层序边界。在其内部的构成上,由于没有明显的侵蚀不整合,也难以将"低位体系域"和"高位体系域"区分开。尤其是在湖盆萎缩或"低位期",湖水退至湖盆中心,水体较浅,很难形成"低位期"的湖底扇。Continental rift subsidence basins were formed during the long time steadily subsiding period of the faults that controlled the depressions.Therefore,the lacustrine level changes were mainly controlled by the interplay of activity rate and characteristics of the faults,transgression and the climate.For the stage and episode activity of the depression controlled by faults,and some sudden circumstance,the curve of the lacustrine level was a two part broken line: the rapid transgression and slow regression.During a single cycle,it formed the Lacustrine Transgression Systems Tract in the lower part and the Lacustrine Regression Systems Tract in the upper part,which can be named as T-R cyclic depositional sequence.The boundaries can be the regional depositional interruption or hiatus reflected by the episode activity of the faults,or the sinking surface induced by sudden transgression.Obviously,the typeⅠboundary formed by large scale exposure did not develop T-R cyclic sequence stratigraphic model.In its inner structure,for there are no obvious unconformities,it was hard to differentiate the LST and HST,especially during the lacustrine shrinking stage or the lowstand stage,which water retreated to the center of the basin,and was hard to develop the lacustrine floor fan in the lowstand stage because of the circumstance of shallow water.

关 键 词：断陷盆地 湖平面变化曲线 层序地层学 T-R旋回 

分 类 号：TE121.3[石油与天然气工程—油气勘探]