摘要
通过对研究区内三叠系、侏罗系露头区裂缝(节理)的观察与统计,对鄂尔多斯中东部地区三叠系、侏罗系裂缝体系的展布特征进行了研究,并分析了裂缝体系形成的构造应力场背景。研究表明在中新生代不同时期构造应力场及其联合作用的控制下,研究区裂缝体系中一组通常为压剪性质,而另一组多为张剪性质,区内NE向和NNE向裂缝体系多具张剪性质。裂缝体系主要发育于脆性岩层当中,且以垂直裂缝(节理)最发育,在某一确定地区裂缝带成对出现,并相互交切,共同组成平面X型共轭剪节理。
Ordos Basin is a polycyclic superimposed basin that was formed in an earlier geological history and has experienced a longer evolution history. At the same time, it is the second largest sedimentary basin on land in China that possesses abundant oil and gas resources and shows bright prospects in oil and gas exploration. It is now one of the important tactical areas in oil and gas exploration in China. Through systematical observation and counting of the field outcrop fractures of Triassic and Jurassic, the author studied the characteristics of distribution of the field outcrop fractures system of Triassic and Jurassic. Then the tectonic stress field background of the formation of fractures system of Triassic and Jurassic was studied. The direction of the main tectonic stress fields in the basin is NW -SE and NNE - SSW and SN during the Indosinian movement, but becomes NW - SE during the Yanshanian movement, and turns to NNE -SSW during the Himalayan movement. The study also shows that the formation of the fracture system of Triassic and Jurassic is controlled by the Mesozoic and Cenozoic Palaeotectonic-stress field and its compound action. Observation of the field outcrop fractures indicates that one of the two sets of fracture systems formed in an area with NE and NNE extensions often possesses tension shear property, and the other possesses compression shear property. The fractures system mainly originated from the brittle formation and most of the fractures are vertical ones. The fractures generally occur in pairs in the study area and the paired fractures often cross each other to form the so-called X-conjugate joints.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2006年第2期168-173,共6页
Geotectonica et Metallogenia
基金
国家重大基础研究前期研究专项项目(2002CCC01400)
国家重点基础研究发展973项目(编号2003CB214601).
关键词
三叠系
侏罗系
裂缝
节理
构造应力场
Triassic
Jurassic
fracture
joint
tectono-stress field
