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GEOTECHNICAL PROPERTIES OF SELECT CONVERGENT MARGIN SEDIMENTS.

机译：精选汇聚沉积物的岩土性质。

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摘要

Geotechnical property analyses on sediments recovered by DSDP drilling on select convergent margins were integrated to determine the variability in these properties along the lower trench inner slope and to delineate the effects of convergence on these properties. Consolidation states range from very underconsolidated to highly overconsolidated with preconsolidation pressures exceeding 46,000 kPa in Quaternary sediments. Underconsolidated sediments are attributed to high sedimentation rates, low sediment permeability relative to the length of the drainage path, laterally applied stresses, induced pore pressures resulting from the subduction of high water content pelagic sediments and physicochemical interparticle bonding. Factors contributing to the state of overconsolidation include tectonically induced overpressures, removal of overburden by mass movement processes, low sediment accumulation rates, and great age. Vertical gradients of index properties also vary greatly with the maximum gradient associated with overconsolidated sediments. Values of porosity exceed 30% at all margins studied suggesting this represents the minimum value attainable solely by the effects of convergence.;Geotechnical property results and site-specific parameters allow classification of the convergent margins studied as either clastic dominated or pelagic dominated margins. Clastic dominated margins formed the basis for the initial geotechnical property model for convergent margin sediments. These margins are characterized by thick trench sediment sequences which are folded and faulted and become progressively more deformed upslope. Convergence rates are low and no well-developed faults or horst and graben structures are evident on the downbending oceanic plate. Highly overconsolidated sediments and index property values which change rapidly with depth result from the slow progressive deformation of trench and lower slope sediments. Examples of clastic dominated margins include the Nankai Trough, Aleutian Trench and Washington continental margin. Pelagic dominated margins are characterized by thin clastic trench sediment sequences overlying pelagic sediments on a rapidly converging oceanic plate. Well-developed faults and/or horst and graben structures are evident on the downbending oceanic plate. Sediment deformation along the trench and lower slope appears limited. These sediments are underconsolidated with gradual and often irregular changes in index property values with depth. Japan Trench and the Middle America Trench-Guatemala margins are considered pelagic dominated. Middle America Trench-Mexico appears to represent an intermediate case having characteristics of both margin types.
机译：对通过在选定的会聚边缘上进行DSDP钻探而获得的沉积物的岩土属性分析进行了综合，以确定沿较低沟槽内坡的这些性质的变化性，并描述了收敛对这些性质的影响。第四纪沉积物中的固结状态范围从极低固结到高度超固结，预固结压力超过46,000 kPa。固结不足的沉积物归因于高沉积速率，相对于排水路径长度而言较低的沉积物渗透性，侧向施加的应力，由高含水浮游沉积物的俯冲作用和物理化学粒子间键合引起的诱导的孔隙压力。导致超固结状态的因素包括构造诱发的超压，通过质量运动过程清除上覆岩层，低沉积物堆积速率和高龄。指数特性的垂直梯度也随与超固结沉积物相关的最大梯度而变化很大。在所研究的所有边际上孔隙度值均超过30％，这表明这仅是收敛作用所能达到的最小值。岩土工程性结果和特定地点的参数允许将所研究的会聚边际分类为碎屑为主或浮游为主的边缘。碎屑为主的边缘形成了汇聚边缘沉积物的初始岩土属性模型的基础。这些边缘的特征是厚厚的沟渠沉积物序列，这些沉积物序列被折叠和断层，并逐渐变得变形更大。汇聚率很低，在俯冲的大洋板块上没有明显发育的断层或地壳和grab陷构造。高度固结的沉积物和指数特性值随深度而迅速变化，这是由于沟渠和低坡度沉积物的缓慢渐进变形造成的。碎屑为主的边缘的例子包括南海海槽，阿留申海沟和华盛顿大陆边缘。远洋主导的边缘的特征是，在快速汇聚的海洋板块上，薄的碎屑海沟沉积物序列覆盖了远洋沉积物。向下弯曲的大洋板块发育良好的断层和/或地壳和grab陷构造很明显。沿沟槽和下坡的沉积物变形似乎是有限的。这些沉积物的固结力不足，其指数特性值随深度的变化往往是不规则的。日本海沟和中美洲海沟-危地马拉的利润被认为是中上层优势。中美洲Trench-Mexico似乎代表了具有两种边际类型特征的中间案例。

著录项

  • 作者

    SHEPHARD, LES EDWARD.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 1981
  • 页码 183 p.
  • 总页数 183
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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