Forward Modeling of Oblique-Thrust Fault-Related-Folds and Instances Analysis
详细信息
- 责任者：Zhang Meng (School of Earth Sciences and Engineering ; Nanjing University ; Nanjing 210046 ; China) ; Jia Dong
- 刊名：Geological Review
- 出版年：2013
- 卷期：59(6)
- 关键词：上冲断层 ; upthrust ; 褶皱 ; folds ; 正演模拟 ; forward modelling
- 页码：p.1207-1217
- 图表：12 illus., 30 refs.
- 分类号：0300
- issnNo：ISSN0371-5736
- isbnNo：CN11-1952/P
摘要
Oblique thrusting is widespread in nature and it is important to analyze the structural geometry of oblique-thrust fault-related-fold and identify whether oblique thrusting exists or not. The pseudo-3D models of faultbend-fold and fault-propagation-fold with different slip directions are constructed by linking a series of 2D forward cross-sections which are built by Trishear4. 5,Gocad and Trishear3D programs to discuss the structural geometry of oblique-thrust fault-related-folds. The results indicate that there are two main distinctions between oblique-thrust fault-related-folds and dip-thrust fault-related-folds. One distinction is that the line linking peak point and midpoint of back limb in the contour map or the line linking core point and midpoint of back limb in the horizontal slice of dip-thrust fault-related-folds is perpendicular to fault strike while the similar line is not perpendicular to fault strike in oblique-thrust fault-related-folds and the line is parallel to slip vector. The other distinction is that the line connecting every peak point of all bedding planes on the cross-sections parallel to fault strike is vertical in dip-thrust fault-related-folds while the line would be oblique to horizontal plane if oblique thrusting exists. The two distinctions can be used to identify whether oblique thrusting exists or not and estimate the slip directions of fault-related-folds.Qiongxi and Daxingxi anticline covered by 3D seismic data in the southwest of Sichuan basin are chosen as two examples for the research. This research indicates that oblique thrusting exists in two anticlines and the intersection angles between slip direction and fault strike are both about 70°. The slip vectors of Qiongxi anticline and Daxingxi anticline are about NE79°and NE77°respectively,which is consistent with the stress field of Longmen Shan since the late Pliocene and the most compressive stress direction inferred from coseismic slip of the Wenchuan earthquake.
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