Abstract Water and melts are crucial in controlling the chemistry, architecture, and dynamics of the Earth's crust. However, how water and melts influence chemical and textural changes of pervaded rocks during transport and how they chemically react with surrounding minerals remain cryptic. We present experimental data illustrating how water-undersaturated and potassium-rich melt in partially molten felsic granulite, or melt lost from such granulite affects the chemistry and texture of an initially, nearly anhydrous eclogite at high-pressure and high-temperature (1.2 GPa, 950 °C) for 20 h. The first experiment simulates interaction of eclogite with granulite having a small proportion of melt (melt = 2 vol%, solids = 98 vol%, with H2O = 0.4 wt% in the system granulite+melt, called in this paper granulite). The second experiment simulates interaction of eclogite with melt (melt = 90 vol%, solids = 10 vol%, H2O = 4 wt% in the system granulite+melt, called in this paper granulite partial melt). Our results show that during granulite-eclogite interaction: i) the melt in the granulite crystallises as a consequence of water diffusion into the eclogite; ii) this water causes partial replacement of garnet by plagioclase-orthopyroxene-magnetite-(±amphibole-) symplectite, whose volumetric proportion correlates with water content in the granulite; and iii) a small proportion of melt from the granulite (≤2 vol%) infiltrates into the eclogite, as documented by mineral overgrowths in granulite and by glass pools with increased potassium content in symplectites and along grain boundaries in the eclogite. Water and melt transfer appears to be effective in causing textural changes, but appears to be ineffective in changing the bulk chemistry of the eclogite, even if local enrichment in potassium and water occurs. Such chemically stealthy diffusion of water and migration of limited amount of melt is able to cause major textural changes accompanied by localised chemical changes at grain-scale that would not be otherwise observed at the scale of the bulk rock composition.

中文翻译：

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地壳岩石中水扩散和熔体迁移的影响：实验研究

摘要 水和熔体对于控制地壳的化学、结构和动力学至关重要。然而，水和熔体在运输过程中如何影响渗透岩石的化学和质地变化，以及它们如何与周围的矿物发生化学反应仍然是个谜。我们提供的实验数据说明了部分熔融的长英质麻粒岩中水不饱和和富含钾的熔体，或从这种麻粒岩中损失的熔体如何影响高压和高温（1.2 GPa， 950 °C) 20 小时。第一个实验模拟榴辉岩与具有小比例熔体的麻粒岩的相互作用（熔体 = 2 vol%，固体 = 98 vol%，在麻粒岩 + 熔体系统中，H2O = 0.4 wt%，在本文中称为麻粒岩）。第二个实验模拟榴辉岩与熔体的相互作用（熔体 = 90 vol%，固体 = 10 vol%，H2O = 4 wt%，在系统麻粒岩+熔体中，在本文中称为麻粒岩部分熔体）。我们的结果表明，在麻粒岩-榴辉岩相互作用期间：i) 由于水扩散到榴辉岩中，麻粒岩中的熔体结晶；ii) 这种水导致石榴石被斜长石-斜方辉石-磁铁矿-（±角闪石-）辛辉石部分替代，其体积比例与麻粒岩中的水含量相关；iii) 来自麻粒岩的一小部分熔体 (≤ 2 vol%) 渗入榴辉岩中，如麻粒岩中矿物过度生长以及随着辛辉岩和榴辉岩中沿晶界钾含量增加的玻璃池所证明的那样。水和熔体转移似乎能有效地引起质地变化，但似乎不能有效改变榴辉岩的整体化学成分，即使发生局部钾和水的富集。这种水的化学隐形扩散和有限量熔体的迁移能够引起重大的结构变化，伴随着颗粒尺度的局部化学变化，否则在大块岩石成分的尺度上是观察不到的。