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Improved Geometric Model of Extensional Fault–bend Folding 被引量:1
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作者 ZHENG Xiaoli HE Guangyu +3 位作者 HU Senqing YAO Zewei WANG Hui LIN Lu 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第6期1847-1857,共11页
Extensional fault-bend folds, also called rollovers, are one of the most common structures in extensional settings. Numerous studies have shown that oblique simple shear is the most appropriate mechanism for quantitat... Extensional fault-bend folds, also called rollovers, are one of the most common structures in extensional settings. Numerous studies have shown that oblique simple shear is the most appropriate mechanism for quantitative modeling of geometric relations between normal faults and the strata in their hanging walls. However, the oblique simple shear has a rather serious issue derived from the shear direction, particularly above convex bends. We use geometric and experimental methods to study the deformation of extensional fault-bend folds on convex bends. The results indicate that whether the fault bends are concave or convex, the shear direction of the hanging wall dips toward the main fault. On this basis, we improve the previous geometric model by changing the shear direction above the convex bends. To illustrate basin history, our model highlights the importance of the outer limit of folding instead of the growth axial. Moreover, we propose a new expression for the expansion index that is applicable to the condition of no deposition on the footwall. This model is validated by modeling a natural structure of the East China Sea Basin. 展开更多
关键词 extensional fault-bend folds shear direction expansion index outer limit of folding EastChina Sea Basin
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龙门山南段邛西断层转折褶皱磁组构及其有限应变 被引量:5
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作者 王开 贾东 +2 位作者 罗良 张明正 李一泉 《地质通报》 CAS CSCD 北大核心 2014年第5期629-640,共12页
龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展... 龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展磁组构研究,分析断层转折褶皱的有限应变特征及区域构造变形机制。实验结果表明,邛西地区上白垩统中主要载磁矿物为高矫顽力的赤铁矿,背斜整体应变较弱,且存在3种类型的磁组构,以沉积磁组构和初始变形磁组构为主,铅笔状磁组构少见,主要存在于靠近褶皱中段的前翼部位,说明断层转折褶皱前翼较后翼和核部应变强,且中段地层应变较其他部位更为强烈。此外,各采样点磁线理的优势方位为近南北向(N10°E),表明邛西断层转折褶皱的形成与龙门山南段晚新生代近东西向的地壳水平缩短有关,暗示龙门山南段的最大主压应力方向在晚新生代存在转变的可能。 展开更多
关键词 磁组构 龙门山南段 邛西断层转折褶皱 新生代变形 有限应变
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斜向逆冲断层相关褶皱的正演模型与实例分析 被引量:3
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作者 张猛 贾东 +2 位作者 王毛毛 李志刚 李一泉 《地质论评》 CAS CSCD 北大核心 2013年第6期1207-1217,共11页
斜向逆冲作用在自然界普遍存在,研究斜向逆冲断层相关褶皱的构造几何学特征,识别断层相关褶皱是否存在斜向逆冲有重要意义。文章采用Trishear 4.5、Gocad以及Trishear3D软件构建一系列不同滑移量的断层转折褶皱和断层传播褶皱的二维正... 斜向逆冲作用在自然界普遍存在,研究斜向逆冲断层相关褶皱的构造几何学特征,识别断层相关褶皱是否存在斜向逆冲有重要意义。文章采用Trishear 4.5、Gocad以及Trishear3D软件构建一系列不同滑移量的断层转折褶皱和断层传播褶皱的二维正演剖面,通过连接一系列不同排列方式的二维剖面建立了三种不同逆冲滑移方向的断层转折褶皱和断层传播褶皱的假三维模型,通过不同假三维模型的比较分析来探讨斜向逆冲断层相关褶皱的构造几何学特征。研究发现,斜向逆冲断层相关褶皱区别于正向逆冲断层相关褶皱的特征主要有两点:①正向逆冲断层相关褶皱层面等高线图上的最高点与后翼等高线中点的连线以及水平切面上的核心点与后翼中点的连线方向均与断层走向垂直,而斜向逆冲断层相关褶皱的最高点以及核心点与后翼中点的连线方向均与断层走向斜交,并且最高点与后翼等高线中点的连线方向或者核心点与后翼中点的连线方向均与逆冲滑移方向一致;②在褶皱平行断层走向纵剖面上,正向逆冲断层相关褶皱各个层面最高点的连线是直立的,而斜向逆冲断层相关褶皱各个层面最高点的连线发生倾斜。通过这两个特征可以判别褶皱是否存在斜向逆冲以及逆冲的方向。将模型分析结果运用到四川盆地西南部三维地震勘探资料所覆盖的邛西背斜和大兴西背斜的实例中。研究结果表明,两个背斜均存在右旋斜向逆冲,逆冲方向与各自断层走向的夹角均为70°左右,邛西背斜和大兴西背斜的逆冲方向分别是NE79°和NE77°左右,这与龙门山南段晚上新世以来的主应力方向以及反演的汶川地震最大主应力方向一致。 展开更多
关键词 斜向逆冲断层相关褶皱 假三维模型 构造几何学 邛西背斜 大兴西背斜
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Two conceptual models of displacement transfer and examples 被引量:4
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作者 GUAN Shuwei1,2, WANG Xin2, YANG Shufeng2, HE Dengfa1 & ZHAO Weidong3 1. Research Institute of Petroleum Exploration and Development, Beijing 100083, China 2. Department of Geosciences, Zhejiang University, Hangzhou 310027, China 3. Tarim Oilfield Company, Korla 841000, China 《Science China Earth Sciences》 SCIE EI CAS 2005年第7期900-911,共12页
This paper presents two conceptual models of displacement transfer, reverse sym- metry model and infinitely equal division model, based on the fault-bend folding theory. If the fault shape is held constant in the tren... This paper presents two conceptual models of displacement transfer, reverse sym- metry model and infinitely equal division model, based on the fault-bend folding theory. If the fault shape is held constant in the trend, then the distribution of slip magnitude, geometry of imbricate structures and its axial surface map all display reverse symmetry on the process of displacement transfer, as called reverse symmetry model in this paper. However, if the ramp height of thrust fault decreases gradually along its strike, the displacement is postulated to be equally and infinitely divided to every thrust that is formed subsequently, this kinematic process is described using infinitely equal division model. In both models, displacement transfer is characterized by the regular changes of imbricate thrusting in the trend. Geometric analysis indicates that the displacement transfer grads can be estimated using the tangent of deflective angle of hinterland structures. Displacement transfer is often responsible for the distortion and branching of the surface anticlines, especially in the region where the multi-level detachment structures is developed. We also present some examples from the frontal structures of the Southern Tianshan fold-and-thrust belt, Xinjiang, China. Displacement transfer between deep imbricate thrusts in the middle segment of Qiulitag anticline zone causes the Kuqatawu and Southern Qiulitag deep an- ticlines left-lateral echelon. The region, where these two deep anticlines overlap, is characterized by duplex structures, and extends about 18 km. The shallow anticline is migrated southward displaying obvious “S” form in this area. 展开更多
关键词 DISPLACEMENT TRANSFER fault-bend foldING reverse symmetry MODEL INFINITELY equal division MODEL Qiulitag zone.
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