...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Fluid expulsion and overpressure development during initial subduction at the Costa Rica convergent margin
【24h】

Fluid expulsion and overpressure development during initial subduction at the Costa Rica convergent margin

机译：哥斯达黎加会聚边缘初始俯冲过程中的流体排泄和超压发展

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A high convergence rate and almost complete subduction of incoming sediments make the Costa Rica convergent margin an extremely dynamic environment in which to examine the interrelationship of tectonically driven loading, compaction, and fluid expulsion. In this study, we investigate overpressure development and fluid expulsion using a numerical modeling method that allows fluid pressures, porosities, and permeabilities to evolve during subduction. Incoming sediments at the Costa Rica margin consist of similar to 180 m of hemipelagic sediments overlying 200 in of pelagic carbonates. Results of the modeling suggest that a permeability-porosity relationship for the hemipelagic sediments derived from laboratory tests (log(k)= -22+7.8 X porosity) is compatible with pore pressures inferred from consolidation tests and compaction rates estimated from sediment porosity and thickness changes, in contrast to results of previous simplified calculations. Comparison of one and two-dimensional modeling indicates that lateral fluid flow modifies the pore pressure profile only moderately, unless the permeability of the pelagic carbonate sediment was an order of magnitude or more higher than indicated by laboratory tests (5 x 10(-16) m(2)). Due to complete subduction of the incoming sediment column, high porosity, and thus high permeability sediments are directly below the decollement zone. Rapid dewatering of these sediments can support high rates of fluid flow along the decollement or upward through the wedge. However, within the first 1.5 km of subduction, drainage leads to a rapid decrease in simulated porosity (0.8 to 0.5) of the uppermost sediments, which would decrease permeabilities to 0.5% of initial values and inhibit further dewatering. (C) 2005 Elsevier B.V. All rights reserved.
机译：较高的收敛速度和即将到来的沉积物几乎完全俯冲，使哥斯达黎加的会聚边缘成为一个极其动态的环境，在该环境中可以检查构造驱动的荷载，压实和流体驱替的相互关系。在这项研究中，我们使用数值模拟方法研究超压的发展和流体的驱逐，该方法允许在俯冲过程中流体压力，孔隙率和渗透率发生变化。哥斯达黎加边缘进入的沉积物包括与180 m的近海沉积物相似，上面覆盖了200 in的中层碳酸盐岩。建模结果表明，实验室测试（log（k）= -22 + 7.8 X孔隙度）得出的半海岸沉积物的渗透率-孔隙率关系与固结试验推断的孔隙压力和根据沉积物孔隙率和厚度估算的压实率兼容与以前的简化计算结果相反。一维模型和二维模型的比较表明，除非上层碳酸盐岩沉积物的渗透率比实验室测试所表明的高一个数量级或更高，否则横向流体流只会适度地改变孔隙压力分布（5 x 10（-16） m（2））。由于进入的沉积物柱完全被俯冲，因此孔隙率高，因此高渗透率的沉积物正好位于折流带下方。这些沉积物的快速脱水可以支持高流量的流体沿着泥浆流或向上穿过楔形物。但是，在俯冲的前1.5公里内，排水导致最上层沉积物的模拟孔隙率迅速降低（0.8至0.5），这将使渗透率降低至初始值的0.5％，并进一步阻止脱水。 （C）2005 Elsevier B.V.保留所有权利。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号