A Scaling for the Permeability of Loose Magma Mush Validated Using X-Ray Computed Tomography of Packed Confectionary in 3D and Estimation Methods From 2D Crystal Shapes
A Scaling for the Permeability of Loose Magma Mush Validated Using X-Ray Computed Tomography of Packed Confectionary in 3D and Estimation Methods From 2D Crystal Shapes
复制标题
使用 3D 包装糖果的 X 射线计算机断层扫描和 2D 晶体形状的估计方法验证松散岩浆糊渗透性的缩放
DOI：
10.1029/2023jb026795
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发表时间：
2023
期刊：
影响因子：
3.4
通讯作者：
Bretagne E
中科院分区：
文献类型：
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作者：
Bretagne E
熔体通过部分熔化的“糊状”地壳区域的渗流，支撑了岩浆迁移、堆积和喷发过程的模型。要准确预测熔体运移速率和堆积时间，需要了解岩浆的水力性质，特别是渗透率。以前的研究证实了立方晶体的类似物，表明晶体形状对渗透率施加了一阶控制，并在这里使用由随机排列的压缩糖果颗粒制成的岩浆模拟物的X射线CT 3D数据集对各向异性自然晶体形状进行了测试。我们使用格子-玻尔兹曼流体流动模拟工具来确定填充颗粒之间的模拟熔体相网络的渗透率。当测量比表面积时，我们发现与我们的数据集在∼0.1log单位内的一致性很好。为了将其扩展到比表面积未知的更典型的情况，我们使用在3D和2D中确定的对象的形状和大小来估计假定长方体近似的比表面积。这些近似解给出了在∼0.5log单位内测得的渗透率的良好结果，并提供了一种从堆积或深部样品的薄片中估算渗透率的方法。我们对形状敏感的方法比现有的岩浆渗透率模型更准确，最接近自然晶体形状的球体。因此，我们建议这些可以在地壳熔体运动的动态岩浆模型中实现，以产生更准确的通量预测。
Melt percolation through partially molten “mushy” regions of the crust underpins models for magma migration, accumulation, and processes that prime systems for eruption. Knowledge of the hydraulic properties of magma mush, specifically permeability, is required for accurate predictions of melt migration rates and accumulation timescales. Previous studies, validated for cuboidal crystal analogs, show that crystal shape exerts a first‐order control on the permeability, and is tested here for anisometric natural crystal shapes using X‐ray CT 3D data sets of magma mush analogs made from packed confectionary particles arranged randomly. We use a lattice‐Boltzmann fluid flow simulation tool to determine the permeability of the analogue melt phase network between the packed particles. We find excellent agreement with our data sets to within ∼0.1 log units, when the specific surface area is measured. To extend this to more typical cases where the specific surface area is unknown, we use the shape and size of the objects determined in both 3D and 2D to estimate the specific surface area assuming a cuboid approximation. These approximate solutions give good results to within ∼0.5 log units of the measured permeability and offer a method by which permeability could be estimated from a thin section of a cumulate or pluton sample. Our shape‐sensitive approach is more accurate than existing models for permeability of magma mush, most approximating natural crystal shapes to spheres. We therefore propose that these could be implemented in dynamic magma mush models for melt movement in the crust to produce more accurate flux predictions.