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首页> 外文期刊>Geochemistry, geophysics, geosystems >Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the lower crust along fast-spreading Mid-Ocean Ridges?
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Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the lower crust along fast-spreading Mid-Ocean Ridges?

机译：高温，高温助热水热通风口可通过沿着快速蔓延的中海脊进行热对流来解释热对流吗？

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摘要

We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper crust and magmatic flow in the lower crust. In an end-member category of models corresponding to effective viscosities (M) lower than 10(13) Pa.s in a melt-rich lower crustal along-axis corridor and permeability k not exceeding approximate to 10(-16) m(2) in the upper crust, the hot, melt-rich, gabbroic lower crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1-2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8-10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and South-East Pacific Rise (SEPR). The lower crustal plumes deliver melt locally at the top of the magmatic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent approximate to 100 MW vents fields. Our models also contribute to current discussions on how the lower crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the lower crust.
机译：我们呈现数值模型，以探索沿快速扩散脊轴的可能耦合，在上地壳的上地壳中的水热对流和下壳体中的岩石流动之间。在对应于低于10（13）Pa的有效粘度（m）的模型的末端成员类别中，富含熔融的下部地壳沿轴轴廊和渗透率k不超过10（-16）m（2 ）在上层地壳中，热，富含熔体的巨型地壳与粘性流体相反，与脊轴平行的对流辊。在这些模型中，我们表明，岩浆 - 水热界面在快速脊的现实深度处落稳，即海底1-2公里。两种地域的对流细胞都是强烈的耦合和宽的水热溢出/羽毛，间隔8-10公里，在岩浆溢出的顶部出现。这种岩浆水热对流耦合可以解释东部（EPR）和东南太平洋崛起（SEPR）的排气场分布。下地壳羽毛在岩浆地平线顶部局部熔化，可能会说明EPR和SEPR的轴向熔体镜片中的富含熔体区域/口袋的观察到的分布。这种熔体的结晶提供了必要的潜热，以维持永久性近似100 mW通风口领域。我们的模型还有助于对快速脊状越下地壳形式的目前讨论：它们提供了从Moho水平到轴向熔体透镜的聚焦运输的可能机制，在那里它们进一步结晶，饲料爆发并被运输沿着和轴外轴产生下壳。

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