海拉尔—塔木察格盆地中部断陷带构造演化与富油构造带成因机制分析

Analysis on tectonic evolution and genetic mechanism of oil-rich structural belt at middle fault depression belt in Hailer-Tamtsag Basin

海拉尔盆地和塔木察格盆地分属于中国和蒙古国,构造上具有统一的构造背景和成盆演化过程。为了整体剖析海拉尔—塔木察格盆地构造演化过程及其对油气运聚成藏的控制作用,本文在明确成盆背景基础上,立足中部断陷带,系统研究了盆地的沉积充填结构、盆地的性质及其叠加演化过程,进而分析了不同演化阶段富油构造带的形成机制及构造演化对油气成藏的控制作用。研究表明,海塔盆地分别由铜钵庙组构成的残留盆地和由南屯组—青元岗组构成的被动裂陷盆地两种不同性质盆地叠加而成,被动裂陷盆地可进一步划分为4个演化阶段,即南一段下、中亚段构成的初始裂陷演化阶段、南一段上亚段—南二段构成的强裂陷演化阶段、大磨拐河组—伊敏组构成的断坳转化演化阶段以及青元岗组构成的坳陷演化阶段。初始裂陷阶段简单剪切走滑变形控制形成的掀斜隆起带,为下部油气系统即南一段下亚段和中亚段的有利勘探方向;强裂陷阶段的纯剪切伸展变形控制形成的中央隆起带和中央背斜带,为中部油气系统即南一段上亚段和南二段的有利勘探方向;断坳转化阶段伊二、三沉积晚期的纯剪切张扭变形控制断裂密集带的形成,并指示下部和中部油气系统的油气运聚成藏及富集部位;伊二、三段末期及坳陷演化阶段的挤压反转变形主要控制了多类型反转构造带的形成,并指示上部次生油气系统即大磨拐河组的油气调整聚集成藏及富集部位。

Hailer Basin and Tamtsag Basin belonging to China and Mongolia respectively, have a uniform tectonic setting and basin evolution process in structure. To analysis the process of tectonic evolution and its control on hydrocarbon accumulation, on the basis of establishment of basin forming background, standing on middle fault depression belt, basin sedimentary filling pattern ,basin properties and basin superimposed evolution process were studied, then formation mechanism of oil-rich structural belts in different phases and the control of structural evolution on hydrocarbon accumulation were analyzed in this paper. Research shows that Hailer-Tamtsag Basin consists of residual basin and passive rift basin, which include Tongbomiao group and Nantun-Qingyuangang group respectively. Passive rift basin consists of four phases, initial rifting period （ lower K1 nI ）, strong rifting period （ upper KL nI and K I n~ ）, rift-depression transformation period（K^d and K^y）, depression period （K2q）. The tihing-uplift zones controlled by simple shearing stress during initial rifting period are favorable exploration directions in lower hydrocarbon system. The central uplift belts and central anticlinal zones controlled by pure shear extension during strong rifting period are favorable exploration directions in middle hydrocarbon system. The fault-condensed belts controlled by extension-shear during riftdepression period indicate hydrocarbon accumulation and enrichment sites in lower and middle hydrocarbon systems. The various types of inversed structural zones controlled by compression inversion during late Yimin and the depression period indicate adjusted accumulation and hydrocarbon enrichment sites in upper hydrocarbon system.