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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Modeling consolidation and dewatering near the toe of the northern Barbados accretionary complex
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Modeling consolidation and dewatering near the toe of the northern Barbados accretionary complex

机译：对巴巴多斯北部增生复合体脚趾附近的固结和脱水进行建模

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At the toe of the northern Barbados accretionary complex, temperature and pore water chemistry data indicate that fluid flow is channeled along the decollement and other shallow thrust faults. We examine mechanisms that may prevent consolidation and maintain high permeability over large sections of the decollement. High-resolution bulk density data from five boreholes show that the decollement is well consolidated at some sites while other sites remain underconsolidated. Underconsolidated decollement behavior is associated with kilometer-scale negative-polarity seismic reflections from the decollement plane that have been interpreted to be fluid conduits. We use a coupled fluid flow/consolidation model to simulate the loading response of a 10-km-long by 680-m-thick slice of sediment as it enters the accretionary complex. The simulations capture 185 ka (5 km) of subduction, with a load function representing the estimated effective stress of the overriding accretionary prism (3.8 degrees taper angle). Simulation results of bulk density in the decollement 3.2 km arcward of the deformation front are compared with observations. The results show that persistent high pore pressures at the arcward edge of the simulation domain can explain underconsolidated behavior. The scenario is consistent with previous modeling results showing that high pore pressures can propagate intermittently along the decollement from deeper in the complex. Simulated seaward fluxes in the decollement (1-14 cm yr(-1)) lie between previous estimates from modeling studies of steady state (<1 cm yr(-1)) and transient (>1 m yr(-1)) flow. Maximum simulated instantaneous fluid sources (2.5 x 10 s(-1)) are comparable to previous estimates. The simulations show minor swelling of incoming sediments (fluid sources similar to -3 x 10(15) s(-1)) up to 3 km before subduction that may help to explain small-scale shearing and normal faulting proximal to the protodecollement. [References: 49]
机译：在巴巴多斯北部增生复合体的趾部，温度和孔隙水的化学数据表明，流体流沿着折弯断层和其他浅冲断层。我们研究了可能会阻止固结并在较大的断面段上保持高渗透率的机制。来自五个钻孔的高分辨率堆密度数据显示，在某些位置上的弯折已充分合并，而其他位置上的合并仍不足。欠固结的脱弯行为与来自脱弯平面的千米级负极地震反射有关，这些地震反射被解释为流体管道。我们使用耦合的流体流动/固结模型来模拟10公里长，680米厚的沉积物进入增生复合体时的荷载响应。该模拟捕获了185 ka（5 km）的俯冲，并带有一个载荷函数，该函数代表了估算的增生棱镜的有效应力（3.8度锥角）。将变形前沿3.2 km的弧段上的疏松堆积密度的模拟结果与观测值进行了比较。结果表明，在模拟域的弧形边缘持续存在较高的孔隙压力可以解释欠固结行为。该情况与先前的模拟结果一致，后者表明高孔隙压力可以从复合体深处沿断层间歇地传播。折弯（1-14 cm yr（-1））中的模拟海流通量位于稳态（<1 cm yr（-1））和瞬态（> 1 m yr（-1））流动模型研究的先前估计值之间。最大的模拟瞬时流体源（2.5 x 10 s（-1））与以前的估计值相当。模拟显示，在俯冲前3 km之前，进入的沉积物（类似于-3 x 10（15）s（-1）的流体源）发生了微小的膨胀，这可能有助于解释小规模的剪切作用和原前弯附近的正断层。 [参考：49]

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