| Improved Geometric Model of Extensional Fault–bend Folding |
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| 作者姓名： | ZHENG Xiaoli HE Guangyu HU Senqing YAO Zewei WANG Hui LIN Lu |
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| 作者单位： | 1 School of Earth Sciences, Zhejiang University, Hangzhou 310027, China;2 CNOOC China Limited, Shanghai Branch, Shanghai 200030, China |
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| 基金项目： | We thank Minqiang Zhang, Rongfu Shi, Fa Xu, Jinshui Liu, Jianpei Zhang, Huirong Gu, Laifu Fang froom CNOOC, and Professor Ancheng Xiao and Xin Wang from Zhejiang University for their useful suggestions and advices. |
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| 摘 要： | 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.
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| 关 键 词： | extensional fault–bend folds shear direction expansion index outer limit of folding East China Sea Basin |
| 收稿时间： | 3/9/2015 12:00:00 AM |
| 修稿时间： | 2015/8/11 0:00:00 |
Improved Geometric Model of Extensional Fault-bend Folding |
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| Authors: | ZHENG Xiaoli HE Guangyu HU Senqing YAO Zewei WANG Hui and LIN Lu |
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| Institution: | 1 School of Earth Sciences, Zhejiang University, Hangzhou 310027, China;,1 School of Earth Sciences, Zhejiang University, Hangzhou 310027, China,2 CNOOC China Limited, Shanghai Branch, Shanghai 200030, China,1 School of Earth Sciences, Zhejiang University, Hangzhou 310027, China;,2 CNOOC China Limited, Shanghai Branch, Shanghai 200030, China and 1 School of Earth Sciences, Zhejiang University, Hangzhou 310027, China; |
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| Abstract: | 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. |
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| Keywords: | extensional fault–bend folds shear direction expansion index outer limit of folding East China Sea Basin |
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