A SIMPLIFIED ANALYSIS OF PARAMETERS CONTROLLING DEWATERING IN ACCRETIONARY PRISMS
A SIMPLIFIED ANALYSIS OF PARAMETERS CONTROLLING DEWATERING IN ACCRETIONARY PRISMS
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DOI：
10.1016/0012-821x(92)90092-a
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发表时间：
1992-04-01
影响因子：
5.3
通讯作者：
DREISS, SJ
中科院分区：
文献类型：
--
作者：
BEKINS, BA;DREISS, SJ
在俯冲带发生的许多动态地质过程之一是海底沉积物被压实导致的脱水，因为它们被吸积到上覆板块上。脱水速率等于泥沙基质速度场的散度。如果对棱镜的几何形状和沉积物的运动作一些简化的假设，就可以用解析的方法估计出这个速率。解析表达式仅取决于泥沙吸积速度、吸积断面厚度、棱柱锥角和泥沙孔隙度分布。溶液的敏感性分析表明，产液分布对沉积物孔隙度分布相对不敏感。然而，该解决方案是非常敏感的楔形锥度角。大角楔可以排出20公里内几乎所有的来水，而小角楔可以保留50公里或更长时间内相当一部分来水。来料截面的厚度也很重要。较薄的吸积剖面的脱水更集中在楔脚附近。通过对北巴巴多斯、马克兰、温哥华和南开增生棱镜的样带分析，说明了一系列的脱水速率和脱水的空间分布。
One of the many dynamic geologic processes taking place at subduction zones is the compaction-driven dewatering of seafloor sediments as they are accreted to the overriding plate. The rate of dewatering is equal to the divergence of the sediment matrix velocity field. This rate can be estimated analytically if simplifying assumptions are made about the geometry of the prism and motion of the sediments. The analytical expression depends only on the sediment accretion velocity, thickness of the accreted section, prism taper angle, and sediment porosity distribution. A sensitivity analysis of the solution shows that the fluid production distribution is relatively insensitive to the sediment porosity distribution. However, the solution is very sensitive to the taper angle of the wedge. High-angle wedges expel almost all of the incoming water within 20 km. while low-angle wedges may retain a significant fraction of the incoming water for 50 or more kilometers. Thickness of the incoming section is also important. Dewatering of thin accreted sections is more concentrated near the toe of the wedge. Analyses of transects through the Northern Barbados, Makran, Vancouver, and Nankai accretionary prisms illustrate a range of dewatering rates and spatial distributions of dewatering.