Joint Development and Paleostress Field in Mesozoic Strata of the Southeastern Ordos Basin
详细信息
- 责任者：Jiang Lin (State Key Laboratory of Lithospheric Evolution ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Wang Qingchen
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(5)
- 关键词：节理 ; joints ; 构造应力场 ; tectonic stress field ; 鄂尔多斯盆地 ; Ordos Basin
- 页码：p.1774-1790
- 图表：illus., 98 refs.
- 分类号：0300
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Six trends of joint sets ( E-W,N-S,ENE-WSW,NNW-SSE,WNW-ESE,NNE-SSW) and three groups of orthogonal joints systems ( EW and SN,ENE-WSW and NNW-SSE,NWW-SEE and NNE-SSW) are recognized in the Mesozoic strata within the southeastern Ordos Basin. The orthogonal joint systems developed in three sequences: D1 with E-W and N-S trening joints,D2 with SEE-NWW and NNE-SSW trending joints,and D3 with ENE-WSW and NNW-SSE trending joints. The fracture spacing index ( FSI) of three sets of joints ( E-W,N-S,ENE-WSW) shows that joint development is controlled by mechanical layer thickness,as well as regional stress. The fracture spacing ratio ( FSR) values of the joint sets ( E-W,N-S,ENE-WSW) indicate regional variation in joint development. Furthermore,the FSR values of the dominant joint sets ( E-W) exceeds the critical ratio of spacing / height,while FSR value of subdominate joint sets ( N-S) are less than the critical value,as indicating that the orthogonal joint system of E-W and N-S trending joint sets developed earlier than others. Three sets of orthogonal joints systems correspond to three paleostress fields respectively. ( 1) The Ordos Basin experienced E-W compression in the Late Jurassic,and the first phase of orthogonal joints systems with the E-W and N-S trending joint sets developed resulting from the far-field effect of NW-directed subduction of the Pacific plate; ( 2) In the Late Cretaceous,the second phase of orthogonal joints system with WNW-ESE and NNE-SSW trending joint sets developed as a result of the continuing subduction of the Pacific plate; ( 3) From the Late Cretaceous to Cenozoic,the third phase of orthogonal joints system with ENE-WSW and NNW-SSE trending joint sets developed in responding to the NE-SW compression as a far-field effect of the Indian plate collision to the Eurasian plate.
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