柴西南地区始新—中新统层序及其对岩性圈闭的控制

The Eocene-Miocene Sequences and Their Controls on Lithologic Traps in Southwestern Qaidam Basin

系统论述了三级层序界面与喜马拉雅运动间的关系,认为研究区始新—中新统发育的8个三级层序界面均为青藏高原隆升过程中不同阶段的响应。研究区最强烈的构造运动至少有4次,代表喜马拉雅运动或青藏高原隆升的4次重要阶段,据此,将喜马拉雅运动划分为4幕。将研究区古近-新近系划分为1个一级层序、4个二级层序、7个三级层序和16个基准面旋回层序,由此建立起研究区的层序地层系统。并系统分析了区内层序对不同类型岩性圈闭的控制作用。认为低位体系域是柴西南地区岩性圈闭发育最有利的层位。研究区最大湖泛面控制了主要岩性油气藏的分布,而层序界面控制了地层超覆油气藏或者不整合遮挡地层油气藏的发育。

In this paper,the relationship between Grade-III sequence interfaces and Himalayan movement is discussed systematically.It is suggested that the eight sequences surfaces were developed in Eocene-Miocene and respondent to different stages of Tibetan plateau uplifting.The strongest tectonic movement in this studied area took place at least four times,representing four significant responses of Himalayan movement or Tibetan plateau uplifting,by which the Himalayan movement can be divided into four episodes.The Tertiary in this area can then be classified as one Class-I sequence,four Class-II sequences,seven Class-III sequences and eleven base-level cycle ones.All of them are composed of the sequence stratigraphic system in this area.By in-depth division and correlation of them,the control effects of them on the different types of lithologic traps are analyzed.It is concluded that the lowstand system tracts（LST） are the most favorable horizons of the lithologic traps development in southwestern Qaidam basin.The main lithologic reservoirs are controlled by the maximum lake flooding surface,and the stratigraphic overlapping reservoirs or unconformity-barriering stratigraphic reservoirs are controlled by the sequence interfaces.