Stratigraphic effects and tectonic implications of the growth of normal faults and extensional basins-猫眼课题宝

正断层和伸展盆地生长的地层效应和构造意义

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1993

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R. Schlische;M. H. Anders

最近对正断层的研究表明：（1）累积位移在断层中心附近最大，向断层尖端减小;（2）断层随着累积位移的增加而延长。半地堑型盆地是大型正断层系统上位移的基本表现，因此预计在其中心附近最深，并随着时间的推移在深度、宽度和长度上增长。盆地生长模型预测，越来越年轻的同伸展地层将上覆基底岩石，特别是如果沉积与盆地容量的增加保持同步。在某些情况下，这些模型预测，如果沉积不能跟上流域容量增加的步伐，就会从沉积物供应超过容量（主要是开放流域）的情况过渡到流域填充不足（主要是封闭流域）的情况。有些盆地是由边界断层相互靠近的原孤立次盆地合并而成的。最古老的地层在每个次盆地中形成限制层序。在固结后不久沉积的地层变薄，朝向在合并带形成的盆内高点，合并带是短期位移不足的区域。对于两条合并的共面断层，合并带位于联合断层系统的中心，位移必须增加，以符合典型的位移剖面和断层长度与位移之间的标度律。因此，最年轻的地层向盆内高压的前位置移动。如果生长断层在伸展方向上重叠，则位移分布在多个展布断层上。盆地内高压则有长期的表现，即使在高压内的总断层位移等于或略大于更深的，侧翼的次盆地。逆冲滑动调节带形成于伸展断层倾向相反的盆地超覆带中。一般来说，故障长度的增长使得在故障尖端需要转移故障。如果两个故障提示都不能传播，则可能形成传输故障。如果只有一个尖端是固定的，则另一个尖端远离固定的尖端传播，并且沉积中心沿相同的方向迁移。上述断层和盆地生长模型为解释伸展盆地的地层记录和提取其构造发展提供了一个有用的框架，如北美东部盆地和山脉以及中生代裂谷的例子所示。Schlische，R.W.，安德斯，M.H.，1996年，Beratan，K.K.，正断层和伸展盆地生长的地层学效应和构造含义，编辑，用沉积学和地层学重建盆地和山脉扩展的历史：科罗拉多博尔德，美国地质学会特别出版物303，第183-203页。2河W. Schlische和M. H.安德斯

Recent research on normal faults has established that (1) cumulative displacement is highest near the fault center and decreases toward the tips and (2) faults lengthen as cumulative displacement increases. Half-graben-type basins are a fundamental manifestation of displacement on large normal fault systems, and thus are expected to be deepest near their centers and to grow in depth, width, and length through time. Basin growth models predict that progressively younger synextensional strata will onlap basement rocks, especially if sedimentation keeps pace with increasing basin capacity. Under certain circumstances, the models predict a transition from conditions in which sediment supply exceeds capacity (predominantly open basin) to one in which the basin is underfilled (predominantly closed basin) if sedimentation cannot keep pace with increasing basin capacity. Some basins evolve through the merger of originally isolated subbasins whose border faults grew toward one another. The oldest strata form restricted sequences in each subbasin. Strata deposited shortly after consolidation thin toward the intrabasin high that forms in the merger zone, a region of short-term displacement deficit. For two merging coplanar faults, the merger zone is located at the center of the combined fault system, and displacement must increase to conform to the typical displacement profile and the scaling law between fault length and displacement. Thus, the youngest strata thicken toward the former location of the intrabasin high. If the growing faults overlap in the extension direction, displacement is distributed on multiple splay faults. The intrabasin high then has long-term expression, even though the summed fault displacement within the high is equal to or slightly greater than that of the deeper, flanking subbasins. Oblique-slip accommodation zones form in the overlap zone of basins whose propagating faults dip in opposite directions. In general, faults growing in length obviate the need for transfer faults at the fault tips. Transfer faults may form if both fault tips cannot propagate. If only one tip is fixed, the other tip propagates away from the fixed tip, and the depocenter migrates in the same direction. The fault and basin growth models described above provide a useful framework for interpreting the stratigraphic record of extensional basins and extracting their tectonic development, as demonstrated by examples from the Basin and Range and Mesozoic rifts of eastern North America. Schlische, R.W., and Anders, M.H., 1996, Stratigraphic effects and tectonic implications of the growth of normal faults and extensional basins, in Beratan, K.K., ed., Reconstructing the History of Basin and Range Extension Using Sedimentology and Stratigraphy: Boulder, Colorado, Geological Society of America Special Publication 303, p. 183-203. 2 R. W. Schlische and M. H. Anders

Stratigraphic effects and tectonic implications of the growth of normal faults and extensional basins

正断层和伸展盆地生长的地层效应和构造意义

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