Abstract Two monazite grains altered during postmagmatic, hydrothermal processes in the Variscan Jawornik granitoid (NE Orlica-Śnieznik Dome, Sudetes, SW Poland) were investigated. Different assemblages of secondary phases replacing and forming close to altered monazite indicate two different courses of the mineral-fluid reactions. The first monazite is surrounded by two zones comprising rhabdophane group minerals (rhabdophane henceforth) and hematite (inner zone) and allanite (outer zone) that form a concentric corona texture. The growth of secondary phases is interpreted as being related to decreasing temperatures below ca. 500 °C. The inner zone formed due to alteration of the monazite that was driven by fluid-induced coupled dissolution-reprecipitation reactions. This alteration resulted in the progression of partial replacement by submicron layers of rhabdophane along the monazite surface and pseudomorphic replacement of a substantial part of the monazite by rhabdophane and hematite. The presence of the hematite suggests oxygen fugacity above the hematite-magnetite buffer. Alteration of the second investigated monazite is related to dissolution induced by a K-bearing alkali fluid, partial replacement by thorianite (ThO2), and overgrowth by K-feldspar with minor titanite formed during the chloritization of biotite and the alteration of feldspars. These results demonstrate that the local character of mineral-fluid reactions can take an entirely different course at the microscale, within a distance of several hundreds of microns. The assemblages of secondary phases replacing two investigated monazite grains indicate that the alteration processes are related to moderate temperature (

中文翻译：

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岩浆后蚀变过程中流体诱导独居石转变的纳米尺度限制——以 Jawornik 花岗岩为例（NE Orlica-Śnieżnik Dome，Sudetes，SW 波兰）

摘要 研究了在 Variscan Jawornik 花岗岩（NE Orlica-Śnieznik Dome，Sudetes，SW 波兰）的岩浆后热液过程中改变的两种独居石颗粒。在蚀变独居石附近置换和形成的不同次生相组合表明矿物流体反应的两种不同过程。第一个独居石被两个区域包围，包括斜纹石族矿物（以下称为斜纹石）和赤铁矿（内带）和钠铝石（外带），形成同心的电晕结构。第二相的生长被解释为与将温度降低到约以下有关。500℃。内部区域是由流体诱导的溶解-再沉淀耦合反应驱动的独居石的蚀变形成的。这种改变导致沿独居石表面被亚微米层的弹纹石部分取代，以及由弹纹石和赤铁矿假晶取代大部分独居石。赤铁矿的存在表明赤铁矿-磁铁矿缓冲层上方的氧逸度。第二个研究的独居石的变质与含钾碱液引起的溶解、钍长石 (ThO2) 部分置换以及黑云母绿泥石化和长石蚀变过程中形成的少量钛铁矿的钾长石过度生长有关。这些结果表明，矿物流体反应的局部特征可以在数百微米的距离内在微观尺度上采取完全不同的过程。