Crustal shear zones and thrust belts: their geometry and continuity in Central Africa
Crustal shear zones and thrust belts: their geometry and continuity in Central Africa
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地壳剪切带和冲断带：中部非洲的几何形状和连续性
DOI：
10.1098/rsta.1986.0028
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
M. Daly
中科院分区：
文献类型：
--
作者：
M. Daly
非洲的前寒武纪造山带通常由韧性剪切带界定，这些剪切带是在大位移的作用下发展起来的，它们标志着地壳移动的部分和稳定部分之间的造山“前沿”。它们被认为是较年轻造山带中地震反射剖面所见的主要地壳反射体。这些造山前缘由剪切带连接，剪切带在造山段之间传递位移或容纳不同的位移。造山带内较小的剪切是差异运动的结果。这些剪切带被认为是通过从平坦的陡峭的结构，并可能有一个逆冲或走滑的意义。它们与前陆冲断带的阶梯轨迹特征相比较。与冲断带一样，剪切带的几何形状可用于估计位移方向，相关的高应变构造岩中发育的区域伸展组构也可用于估计位移方向。中非以前曾被描述为一个复杂的晚元古代“移动的带”网络。在这些带的类似位移和时间等效性的认识允许他们重新解释的一个链接的逆冲和走滑剪切带系统。例如达马兰、卢菲利安、赞比西和乌金甘系统。这些造山带有着相似的位移图象和广泛的时间等效性，显然是在大陆尺度的下地壳剪切带中相连的。这一剪切带系统似乎是在一个单一的构造格架下发展起来的
The Precambrian orogenic belts of Africa are often defined by ductile shear zones which developed in response to large displacements, and which mark orogenic ‘ fronts ’ between mobile and stable parts of the crust. They are thought to represent the major crustal reflectors seen by seismic reflection profiling in younger orogenic belts. These orogenic fronts are connected by shear zones that transfer displacement or accommodate different displacements, between orogenic segments. Smaller shears within an orogenic belt occur as a result of differential movements. These shear zones are seen to pass from flat-lying to steep structures and may have a thrust or strike-slip sense. They compare with the staircase trajectories characteristic of foreland thrust belts. In common with thrust belts, the geometry of the shear zones can be used to estimate displacement direction, as can regional extensional fabrics developed in the associated high-strain tectonites. Central Africa has been previously described as a complex network of late Proterozoic ‘mobile belts’. The recognition of similar displacements and time equivalence in these belts allows their reinterpretation in terms of a linked thrust and strike-slip shear-zone system. An example is the Damaran, Lufilian, Zambezi and Ukingan system. These orogenic belts share a similar displacement picture and broad time equivalence and were apparently linked in a lower crustal shear zone of continental dimensions. This shear zone system appears to have developed under a single tectonic framework