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Instantaneous rock transformations in the deep crust driven by reactive fluid flow
Nature Geoscience ( IF 15.7 ) Pub Date : 2020-03-16 , DOI: 10.1038/s41561-020-0554-9
A. Beinlich , T. John , J. C. Vrijmoed , M. Tominaga , T. Magna , Y. Y. Podladchikov

Fluid–rock interactions are a fundamental component of geodynamic processes. They link mass and energy transfer with large-scale tectonic deformation and drive mineral deposit formation, carbon sequestration and rheological changes of the lithosphere. Spatial evidence indicates that fluid–rock interactions operate on length scales that range from the grain boundary to tectonic plates, but the timescales of regional fluid–rock interactions remain essentially unconstrained. Here we present observations from an exceptionally well-exposed fossil hydrothermal system from an ophiolite sequence in northern Norway that we use to inform a multielement advection–diffusion–reaction transport model. We calculated the velocity of the fluid-driven reaction fronts and found that they can propagate at up to 10 cm per year, equivalent to the fastest tectonic plate motion and mid-ocean-ridge spreading rates. Propagation through the low-permeability rocks of the mid-crust is facilitated by a transient, reaction-induced permeability increase. We conclude that large-scale fluid-mediated rock transformations in continental collision and subduction zones occur on timescales of tens of years when reactive fluids are present. We infer that natural carbon sequestration, ore deposit formation and transient and long-term petrophysical changes of the crust proceed instantaneously, from a geological perspective.



中文翻译:

反应流体驱动深壳中的瞬时岩石转变

流体-岩石相互作用是地球动力学过程的基本组成部分。它们将质量和能量转移与大规模构造变形联系在一起,并驱动矿床形成,碳固存和岩石圈的流变变化。空间证据表明,流体-岩石相互作用的长度范围从晶粒边界到构造板块,但区域流体-岩石相互作用的时间范围基本上不受限制。在这里,我们从挪威北部蛇绿岩序列中一个异常暴露的化石热液系统中观察到的数据,我们将其用于告知多元素对流-扩散-反应运输模型。我们计算了流体驱动的反应前沿的速度,发现它们可以以每年10 cm的速度传播,相当于最快的构造板块运动和洋中脊扩散速率。通过瞬变,反应引起的渗透率增加,促进了中地壳低渗透率岩石的传播。我们得出的结论是,当存在反应性流体时,在大陆碰撞和俯冲带中的大规模流体介导的岩石转变发生在数十年的时间尺度上。我们推断,从地质学角度来看,天然碳固存,矿床形成以及地壳的瞬时和长期岩石物理变化是瞬时进行的。我们得出的结论是,当存在反应性流体时,在大陆碰撞和俯冲带中的大规模流体介导的岩石转变发生在数十年的时间尺度上。我们推断,从地质学角度来看,天然碳固存,矿床形成以及地壳的瞬时和长期岩石物理变化是瞬时进行的。我们得出的结论是,当存在反应性流体时,在大陆碰撞和俯冲带中的大规模流体介导的岩石转变发生在数十年的时间尺度上。我们推断,从地质学角度来看,天然碳固存,矿床形成以及地壳的瞬时和长期岩石物理变化是瞬时进行的。

更新日期:2020-04-24
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