Kilometre-scale polygonal seabed depressions in the Hatton Basin, NE Atlantic Ocean: Constraints on the origin of polygonal faulting
Kilometre-scale polygonal seabed depressions in the Hatton Basin, NE Atlantic Ocean: Constraints on the origin of polygonal faulting
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大西洋东北部哈顿盆地的公里级多边形海底凹陷：对多边形断层起源的限制
DOI：
10.1016/j.margeo.2012.09.013
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发表时间：
2012
期刊：
影响因子：
2.9
通讯作者：
K. Hitchen
中科院分区：
文献类型：
--
作者：
C. Berndt;C. Jacobs;Alan E. Evans;A. Gay;G. Elliott;D. Long;K. Hitchen
多边形断层是全世界沉积盆地中普遍存在的现象。它改变了盆地规模的流体流动模式并改变了沉积物的物理性质，使其对于碳氢化合物勘探和地质灾害分析非常重要。人们普遍认为，多边形断层模式源自宿主沉积物的脱水和压实，但对于控制多边形断层的过程存在争议。来自大西洋东北部哈顿盆地的新多波束测深数据显示，海底有深达 10 m、宽 200-600 m 的海槽。它们相互连接形成数百米宽的多边形，即与 3D 地震数据中观察到的埋藏多边形断层系统的大小相似。这些槽是对称的，类似于细长的麻子。先前未发表的来自同一地区的高分辨率二维地震数据显示，地震扰动区类似于在其他地方的麻点下观察到的管道，以及具有多边形断层系统所有特征的断层。对宽阔扰动区的观察是神秘的，因为它们似乎遵循多边形海底模式。观测到的多边形沉积物收缩系统的范围很大，覆盖近 37,000 平方公里。我们计算出约 2600 平方公里的可能含碳流体已从该系统中排出，我们预计这将影响底栖生态系统，尽管到目前为止，关于化学合成栖息地的证据有限。
Polygonal faulting is a widespread phenomenon in sedimentary basins worldwide. It changes basin-scale fluid flow patterns and alters the physical properties of the sediments making it important for hydrocarbon exploration and geohazard analysis. It is generally accepted that polygonal fault patterns derive from dewatering and compaction of the host sediments, but there is debate regarding the processes that control polygonal faulting. New multibeam-bathymetry data from the Hatton Basin, NE Atlantic, show up to 10m deep and 200–600m wide troughs at the seabed. They connect to each other forming polygons that are several hundred metres across, i.e. of similar size as buried polygonal fault systems observed in 3D seismic data. The troughs are symmetrical and resemble elongated pockmarks. Previously unpublished high-resolution 2D seismic data from the same area show seismic disturbance zones similar to pipes observed under pockmarks elsewhere as well as faults that have all the characteristics of polygonal fault systems. The observation of the wide disturbance zones is enigmatic, as they appear to follow the polygonal seafloor pattern. The observed extent of the polygonal sediment contraction system is substantial covering almost 37,000km2. We calculate that some 2600km3of possibly carbon-bearing fluids have been expelled from this system and we expect that this will affect the benthic ecosystems, although so far there is only limited evidence for chemosynthetic habitats.