中国中西部燕山期构造特征及其油气地质意义  

Yanshanian tectonic features in west-central China and their petroleum geological significance

作　　者：贾承造[1] 魏国齐[2] 李本亮[2] 

机构地区：[1]中国石油天然气股份有限公司,北京100011 [2]中国石油勘探开发研究院天然气地质研究所,河北廊坊065007

出　　处：《石油与天然气地质》2005年第1期9-15,共7页Oil & Gas Geology

基　　金：国家"十五"科技攻关项目(2004BA616A-04-01)

摘　　要：中国中西部地区燕山期构造运动具有普遍性,首先表现在白垩系与侏罗系呈不整合接触,甚至第三系直接与侏罗系呈不整合接触;其次,中西部地区各盆地均具有燕山期的古构造;再次,晚侏罗世到早白垩世,拉萨地体和羌塘地体沿班公湖-怒江缝合带发生碰撞挤压,地壳抬升,在羌塘盆地和拉萨地块沉积了一套红色磨拉石建造,白垩系与侏罗系形成明显的角度不整合。燕山期构造运动的特征为:区域性构造抬升,盆地沉积范围收缩,构造变形相对较为微弱;在造山带前缘普遍发育大套的砂砾岩粗粒沉积;以及造山带内部局部地区的岩浆活动。燕山期构造运动对油气成藏的意义主要是①加速烃源岩热演化作用,致使中、西部地区发育的晚古生界和上三叠统—早中侏罗统两套主要的煤系烃源岩,分别在燕山晚期进入生、排烃高峰期,或开始生烃;②燕山期古构造与烃源岩生、排烃适时配置,有利于油气早期聚集成藏;③经喜山期构造运动对油气重新调整后,在邻近燕山期古油(气)藏的新圈闭中利于重新聚集成藏,形成次生油气藏;④燕山期的构造抬升,以低水位体系域沉积的粗粒碎屑物质形成良好的储集砂体,有利于油气聚集成藏。Yanshanian tectonic movement was very common in west-central China. Firstly, it appears as the unconformity between Cretaceous and Jurassic,and even the Tertiary directly and unconformably contact with Jurassic. Secondly, Yanshanian palaeostructures occur in every basin in west-central China. Thirdly, Lasha and Qiangtang terrains collided along Bangonghu-Nujiang suture zone, leading to the uplift of earth crust, a set of red molasse formation was deposited both in Qiangtang basin and Lasha terrain. As a result, an apparent angular unconformity occurs between Cretaceous and Jurassic. Yanshanian tectonic movement is characterized by the followings: regional tectonic elevation led to the shrinkage of sedimentary basin and relatively weak tectonic deformation; large set of coarse glutenite deposits were commonly developed in the front-edge of orogenic belt; magmatic activity occurred in local area within the orogenic belt. The significances of Yanshanian tectonic movement to hydrocarbon accumulation include: (1) Speed up of the thermal evolution of source rocks made the two major coal measure source rocks, Upper Paleozoic and Upper Triassic-Lower and Middle Jurassic, in west-central China entering the peaks of hydrocarbon generation and expulsion or began to generate hydrocarbons respectively in Late Yanshanian; (2) The timing of Yanshanian palaeostructures and hydrocarbon generation and expulsion of source rocks would be favorable for early accumulation of hydrocarbons; (3) Readjustment of oil and gas by Himalayanian tectonic movement would be favorable for the formation of secondary oil and gas pools in new traps near the Yanshanian fossil oil and gas reservoirs; (4) Yanshanian tectonic elevation led to the development of good reservoirs of coarse clastic rocks deposited in low water level system tract, thus they would be favorable for reservoiring of oil and gas.

关 键 词：燕山运动 生烃期 储集层 油气成藏 

分 类 号：TE111.2[石油与天然气工程—油气勘探]