Microtextural and chemical evidence from gabbros indicates that melts may react with the crystal framework as they migrate through crystal mushes beneath mid-ocean ridges; however, the importance of this process for the compositional evolution of minerals and melts remains a matter of debate. Here we provide new insights into the extent by which melt-rock reaction process can occur in oceanic gabbros by conducting a detailed study of cryptic reactive melt migration as preserved in an apparently unremarkable, homogeneous olivine gabbro from deep within a section of the plutonic footwall of the Atlantis Bank core complex on the Southwest Indian Ridge (International ocean discovery program Hole U1473A). High-resolution chemical maps reveal that mineral zoning increases toward and becomes extreme within a cm-wide band that is characterized by elevated incompatible trace element concentrations and generates extreme more/less incompatible element ratios. We demonstrate that neither crystallization of trapped melt nor diffusion can account for these observations. Instead, taking the novel approach of correcting mineral-melt partition coefficients for both temperature and composition, we show that these chemical variations can be generated by intergranular reactive porous flow of a melt as it migrated through the mush framework, and whose composition evolved by melt-rock reaction as it progressively localized into a cm-scale reactive channel. We propose that the case reported here may represent, in microcosm, a preserved snapshot of a generic mechanism by which melt can percolate through primitive mafic (olivine gabbro) crystal mushes, and be modified toward more evolved compositions via near-pervasive reactive transport.

辉长岩的微观结构和化学证据表明，熔融物可能会通过中洋洋脊下方的晶体糊状迁移而与晶体骨架发生反应。然而，这一过程对于矿物和熔体成分演化的重要性仍然存在争议。在这里，我们通过对神秘的反应性熔体迁移进行的详细研究，提供了对于岩石辉石在海洋辉长岩中发生程度的新见解，这些隐秘的反应性熔岩迁移被保留在一个明显不明显的均质橄榄岩辉辉岩中，该辉长岩来自深部的深部沉积岩层。位于西南印度洋脊上的亚特兰蒂斯银行核心综合设施（国际海洋发现计划Hole U1473A）。高分辨率化学图谱显示，矿物带向厘米级波段增加并变得极端，该波段的特征是不相容的痕量元素浓度升高，并且产生了更多或更少的不相容元素比率。我们证明捕获的熔体的结晶和扩散都不能解释这些现象。相反，采用校正温度和成分的矿物熔体分配系数的新颖方法，我们表明，当熔体迁移通过糊状骨架时，熔体的晶间反应性多孔流可产生这些化学变化，并且熔体的成分会发生演变。岩石反应，因为它逐渐定位在厘米级的反应通道中。我们建议，从微观上看，这里报道的病例可能代表