Sediment subduction versus accretion around the Pacific
Sediment subduction versus accretion around the Pacific
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DOI：
10.1016/0040-1951(83)90114-2
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发表时间：
1983-12
期刊：
影响因子：
2.9
通讯作者：
T. Hilde
中科院分区：
文献类型：
--
作者：
T. Hilde
俯冲洋板块通常被正断层破坏，因为它们向下弯曲进入俯冲带，通常形成规则的地堑。断层走向与海沟轴线平行或接近平行，最常见的间距和宽度为5-10公里。破裂最初发生在外部地形高点附近，垂直位移或地堑深度随着板块下降而增加，在许多海沟轴线处为400 m或更深。有人建议，地堑提供的俯冲板块的表面内的空隙空间，俯冲平面以下，到其中的沟槽沉积物被构造位移，从而俯冲。在太平洋周围，仅有的明显的弧前沉积物堆积区域是地堑结构缺失或被厚沉积物掩盖的地方。即使在这些情况下，沉积物俯冲，包括在俯冲板块地堑或其他机制，必须援引来解释弧前沉积物体积相对较小的计算吸积量的基础上的历史收敛。在海沟沉积物体积小于地堑体积的地方，地堑可能会磨损覆盖板块的前缘和下侧，并淹没被侵蚀的物质。结果表明，沉积物俯冲作用在环太平洋地区占主导地位，俯冲板块弯曲形成的地堑构造是沉积物俯冲和构造侵蚀的主要因素。
Subducting oceanic plates are typically broken by normal faults as they bend downward into subduction zones, usually forming regular patterns of grabens. The faults strike parallel or subparallel to the trench axes and are most commonly 5–10 km in spacing and width. Rupture occurs initially near the outer topographic high and vertical displacement or graben depth increases as the plate descends, the 400 m or more at many trench axes. It is suggested that the grabens provide void spaces within the surface of the subducting plate, below the plane of subduction, into which the trench sediments are tectonically displaced and thus subducted. Around the Pacific, the only regions of apparent fore-arc sediment accretion are where the graben structures are missing or masked by thick sediment deposits. Even in these cases sediment subduction, by inclusion in subducting plate grabens or by other mechanisms, must be invoked to explain the relatively small fore-arc sediment volumes compared to calculated accretion volumes based on historical convergence. Where trench sediment volumes are small compared to the graben volumes the grabens may abrade the leading edge and underside of the overriding plate and subduct the eroded material. It is concluded that sediment subduction is dominant around the Circum-Pacific and that the bending-induced graben structures of the subducting plates are a major factor for sediment subduction and tectonic erosion.