TRAPPING OF AQUEOUS FLUIDS IN THE DEEP CRUST
TRAPPING OF AQUEOUS FLUIDS IN THE DEEP CRUST
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DOI：
10.1029/gl017i008p01129
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发表时间：
1990-07-01
影响因子：
5.2
通讯作者：
BAILEY, RC
中科院分区：
文献类型：
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作者：
BAILEY, RC
在深部（韧性）地壳中自由的含水流体在那里停留的时间在地质学上是很短的。如果不被逆行变质反应消耗，它们会迅速向上蒸发。这可以通过将岩浆在延展性宿主中的渗流理论应用于含水流体渗流问题来证明。在脆性-延性转变之下，延性的热活化足以促进孔隙度的快速演化，从而允许快速的流体输送。然而，在脆性-韧性转变之上的较冷的地壳中，这种机制消失了。因此，过渡区流体积聚产生的流体超压必然导致水力压裂，而不是孔隙膨胀。在水平压应力区域，即稳定大陆地壳中最常见的情况，这些裂缝将是水平的。因此，通过下地壳上升或从下地壳中释放出来的含水流体可能会（至少在最初）在高水平渗透率但低垂直渗透率的水平扩展储层的脆性-韧性过渡阶段积累。
Free aqueous fluids in the deep (ductile) crust have residence times there which are very short in geological terms. If not consumed by retrograde metamorphic reactions, they empty very rapidly upwards. This can be shown by applying the theory of magma percolation in a ductile host to the problem of aqueous fluid percolation. Below the brittle‐ductile transition thermal activation of ductility is strong enough to facilitate the rapid evolution of porosity and consequently allow rapid fluid transport. In the cooler crust above the brittle‐ductile transition, however, this mechanism vanishes. As a consequence, fluid overpressures resulting from the accumulation of fluid in the transition zone must induce hydraulic fracturing rather than pore inflation. In regions of horizontally compressive regional stress, the commonest situation in stable continental crust, these fractures will be horizontal. Aqueous fluids rising through or liberated from the lower crust will therefore probably accumulate (at least initially) at the brittle‐ductile transition in horizontally extensive reservoirs with high horizontal permeability but low vertical permeability.