Geometric and experimental models of extensional fault-bend folds
Geometric and experimental models of extensional fault-bend folds
复制标题
伸展断层弯曲褶皱的几何和实验模型
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
R. Schlische
中科院分区：
文献类型：
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作者：
M. Withjack;R. Schlische
摘要 我们使用几何和实验模型来研究伸展断层弯曲褶皱的发育。几何模型表明，断层形状、断层位移和加蚀侵蚀模式深刻影响生长层分布、前生长层和生长层倾角的大小和方向，以及前生长层和生长层褶皱外界的位置和倾角。如果相对于断层位移速率的加蚀/侵蚀速率随时间变化，就会形成复杂的结构和地层图案。实验模型（使用干砂和湿粘土）表明，几种变形样式可以适应伸展断层弯曲褶皱。在砂模型中，一些相对主要的次生对立正断层适应了大部分上盘变形。预生长层虽然有断层，但仍然平坦。有效剪切方向与对位正断层平行，剪切角约为60°～65°。在粘土模型中，大量相对较小的次生正断层（对立的和合成的）和碎裂流适应了大多数上盘变形。变形的预生长层和生长层缓慢地向主断层倾斜。有效剪切角（35°–50°）远小于相对正断层的倾角。在大剪切角（60°）的砂模型和几何模型中，主正断层位移较多，上盘塌陷区域相对狭窄。在小剪切角（35°）的粘土模型和几何模型中，主正断层上发生的位移较小。相反，上盘会大幅伸展并在相对较宽的区域内塌陷。
Abstract We use geometric and experimental models to study the development of extensional fault-bend folds. The geometric models show that fault shape, fault displacement, and patterns of aggradation/erosion profoundly affect the distribution of growth beds, the magnitude and direction of dip of pregrowth and growth beds, and the location and dip of the outer limit of folding in pregrowth and growth beds. Complex structural and stratigraphic patterns develop if the rate of aggradation/erosion relative to the rate of fault displacement changes through time. The experimental models (with dry sand and wet clay) show that several deformational styles can accommodate extensional fault-bend folding. In sand models, a few, relatively major, secondary antithetic normal faults accommodate most hanging wall deformation. Pregrowth layers, although faulted, remain flat. The effective shear direction parallels the antithetic normal faults, and the shear angle is about 60°–65°. In clay models, numerous, relatively minor, secondary normal faults (antithetic and synthetic) and cataclastic flow accommodate most hanging wall deformation. The deformed pregrowth and growth layers dip gently toward the main fault. The effective shear angle (35°–50°) is considerably less than the dip of the antithetic normal faults. In the sand models and geometric models with a large shear angle (60°), more displacement occurs on the main normal fault and the hanging wall collapses in a relatively narrow zone. In the clay models and geometric models with a small shear angle (35°), less displacement occurs on the main normal fault. Instead, the hanging wall stretches substantially and collapses in a relatively wide zone.