Controls on Early-Rift Geometry: New Perspectives From the Bilila-Mtakataka Fault, Malawi
Controls on Early-Rift Geometry: New Perspectives From the Bilila-Mtakataka Fault, Malawi
复制标题
对早期裂谷几何形状的控制：马拉维比利拉-姆塔卡塔卡断层的新视角
DOI：
10.1029/2018gl077343
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发表时间：
2018
影响因子：
5.2
通讯作者：
Hodge M
中科院分区：
文献类型：
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作者：
Hodge M
我们使用110公里长的Bililila-Mtakataka故障在amagmatic南部东非裂谷，马拉维，调查早期裂谷几何形状的控制在一个主要的边界断层的规模。沿着沿着14 ± 8米高的悬崖的形态变化定义了6个10至40公里长的段，这些段要么与叶理平行，要么与叶理和当前区域延伸方向倾斜。由于陡坎既不始终平行于叶理，也不很好地定向于当前区域的延伸方向，我们认为，分段表面表达与局部重新激活的定向较弱的浅层组构上方的一个广泛连续的结构在深度。使用几何模型，最佳拟合地下结构的几何形状与最近地震活动的局部应变场一致。总之，在这个早期裂谷中，预先存在的弱点仅局部控制地下的边界断层几何形状。
We use the ∼110‐km long Bilila‐Mtakataka fault in the amagmatic southern East African Rift, Malawi, to investigate the controls on early‐rift geometry at the scale of a major border fault. Morphological variations along the 14 ± 8‐m high scarp define six 10‐ to 40‐km long segments, which are either foliation parallel or oblique to both foliation and the current regional extension direction. As the scarp is neither consistently parallel to foliation nor well oriented for the current regional extension direction, we suggest that the segmented surface expression is related to the local reactivation of well‐oriented weak shallow fabrics above a broadly continuous structure at depth. Using a geometrical model, the geometry of the best fitting subsurface structure is consistent with the local strain field from recent seismicity. In conclusion, within this early‐rift, preexisting weaknesses only locally control border fault geometry at subsurface.