Fluid dynamics and subsurface sediment mobilization processes: an overview from Southeast Caribbean
Fluid dynamics and subsurface sediment mobilization processes: an overview from Southeast Caribbean
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流体动力学和地下沉积物动员过程：东南加勒比海概述
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
F. Schneider
中科院分区：
文献类型：
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作者：
E. Deville;S. Guerlais;S. Lallemant;F. Schneider
本文讨论了构造活动区和富页岩环境中地下泥沙活化过程的起源和动力学。特立尼达和巴巴多斯棱镜南部的例子说明了这一点。在加勒比海东南部的这一地区，地球物理采集惊人地表明，在巴巴多斯棱镜南部和奥里诺科河活动浊流系统之间的干扰区域，沉积物动员特征得到了广泛发展。大量的泥火山通过水力裂缝系统沿斜坡背斜山顶发育。该地区还显示出与保存完好的浊积岩和半深海沉积物大规模抬升相对应的构造趋势，这些沉积物切割了周围的沉积物。其中一些构造由于塌陷构造、火山口和叠加的泥火山的发展而变得复杂。泥火山喷出的活化沉积物既有液化的泥质，也有来自深层的细砂质，以及被泥浆管道穿透的各种较浅的地层。在巴巴多斯棱镜和特立尼达，排出的泥浆含有丰富的细长、棱角和机械损坏的石英颗粒，这些颗粒可能是剪切和坍塌的深层砂岩储层发出的碎屑流。外来碎屑和角砾岩主要是水力压裂作用的结果。在特立尼达，气相主要是与深层生烃有关的深部热成气甲烷。地下沉积物活化与盐活化的显著不同在于控制超压页岩活化和诱导沉积物液化的流体动力学所起的作用。在管道周围形成了几个变形过程的反应链。巨大的沉积隆起对应于层状固体水平的大运动，可能是由于先前存在的泥火山系统的构造反转。所有这些现象都受控于深部超压的发展。在所研究的地区没有观察到穿透页岩底辟的证据。
This paper discusses the origin and the dynamics of subsurface sediment mobilization processes in tectonically mobile regions and shale‐rich environment. This is illustrated by the example of Trinidad and the south of the Barbados prism. In this area of the southeast Caribbean, geophysical acquisitions have spectacularly shown the widespread development of sediment mobilization features in the interference area between the southern part of the Barbados prism and the active turbidite system of the Orinoco. Numerous mud volcanoes are especially developed along ramp anticline crests through hydraulic fracture systems. The area also exhibits trends of structures that correspond to massive uplifts of well‐preserved turbidite and hemipelagic sediments that cut up the surrounding sediments. Some of these structures are complicated by the development of collapse structures, calderas and superimposed mud volcanoes. The mobilized sediments expelled by the mud volcanoes are not only liquefied argillaceous but also fine sandy material from deep horizons, and various shallower formations pierced by the mud conduits. Both in the Barbados prism and in Trinidad, the expelled mud is rich in thin, angular and mechanically damaged quartz grains, which are probably cataclastic flows issued from sheared and collapsed deep sandy reservoirs. The exotic clasts and breccias result mostly from hydraulic fracturing. In Trinidad, the gas phase is mainly deep thermogenic methane associated with hydrocarbon generation at depth. Subsurface sediment mobilization notably differs from salt mobilization by the role taken by the fluid dynamics that control overpressured shale mobilization and induce sediment liquefaction. A reaction chain of several deformation processes develops around the conduits. Massive sedimentary uplift corresponds to large movements of stratified solid levels, possibly due to the tectonic inversion of pre‐existing mud volcano systems. All these phenomena are controlled by the development of overpressure at depth. No evidence for piercing shale diapirs has been observed in the area studied.