摘要
伊通地堑是我国东部中—新生代发育的走滑-伸展盆地。地震剖面解释和钻井岩芯观察表明,伊通地堑古近系永一段底部发育一个面积>400km2、厚达250m的大型湖底扇,作为永一段层序的低位扇体,其主要由细-中砂岩和少量砂砾岩组成,砂岩中含较多砂岩角砾、泥岩碎块或泥砾,卷曲纹理、液化变形、球状-枕状构造、微断层等准同生变形构造十分发育,体现了湖底扇主要为滑塌型水下泥石流沉积。在下伏奢岭组沉积之后,研究区遭受了构造反转挤压和抬升剥蚀;随后发生强烈的正断活动,并伴随火山喷发和地震活动,永一段湖底扇正是这些构造事件综合作用的结果,其发育预示着新一幕构造沉降的开始和盆地进入新的演化阶段。尽管扇体规模较大,但由于岩性结构混杂,储层物性极差,不利于油气藏的形成。
Yitong graben is a strike-slip and extensional basin in Meso-Cenozoic, the eastern China. After seismic profile explaining and well core observing, a large-scale sublacustrine fan complex with an area of 400 km^2 and thickness of 250 m was identified at the bottom of Member Yongl, Paleogene of the graben. As the low-stand fan of three-order sequence Yongl, It was mainly composed of fine to middle-grained sandstone and a little gravel stone which bore many sandstone breccias, mudstone shivers or muddy gravels together with various pene-contemporaneous deformation structures such as convolute bedding, liquefied distortion, ball and pillow structure, microfault etc. , so it was determined to be dominantly subaqueous debris flow deposit due to slump. After underlying Sheling Formation had developed, the research area suffered reverse tectonic extrusion, denudation, and then violent normal-faulting accompanied with volcano breaking forth and earthquake activity. The fan at Member Yongl was synthetically caused by above tectonic affairs, and it indicated that a new episode of tectonic subsidence occurred and that the garben came into a new evolution stage. Owing to the farraginous lithology composite and very poor reservoir capacity, this sublacustrine fan was not favorite to oil and gas accumulation although its size was very large.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2009年第4期550-557,共8页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号40872077)资助成果
关键词
伊通地堑
湖底扇
滑塌
水下泥石流
构造事件
Yitong graben
sublacustrine fan
slump
subaqueous debris flow
tectonic affair
