Compared to average crustal abundances, high field strength elements (HFSEs) including Zr, Nb, Hf, Ta, and U are commonly enriched in rare element pegmatites. Albite-spodumene pegmatites may show economic grades of these elements, along with Sn, primarily in oxide minerals. Processes leading to enrichment and precipitation of HFSEs in these rocks are not well understood. Here, we characterize the textures and geochemistry of minerals of HFSEs, tin, and base metals in the Leinster albite-spodumene pegmatites. We use these data to infer processes for enrichment and precipitation of these metals during pegmatite crystallization, especially subsolidus processes.The Leinster albite-spodumene pegmatites are located within the East Carlow deformation zone on the eastern flank of the Caledonian S-type Leinster batholith, southeast Ireland. The final crystallization stages of these pegmatites are characterized by autometasomatism and hydrothermal overprint leading to in situ greisenization and precipitation of massive, commonly replacive, albitites. Cassiterite and HFSE minerals (columbite-tantalite and zircon) crystallized predominantly during these late stages. Crystals of HFSE minerals that precipitated during the early magmatic stages commonly exhibit evidence of resorption and additional growth during later stages. Others, such as microlite and uraninite, only crystallized during metasomatism or from hydrothermal fluids. Base metal sulfides are among the last precipitates from these fluids.We present a detailed paragenetic sequence for the Leinster albite-spodumene pegmatites and show that late-stage aqueous fluids transported HFSEs, especially after all the melt had crystallized. Tantalum enrichment seems to have been controlled by processes affecting the entire crystallizing medium, as opposed to fractional crystallization of columbite-tantalite. The textures and parageneses described in the present and our previous work are well explained by element partitioning between coexisting liquids with characteristics similar to those described in published melt-melt-fluid immiscibility models for rare element pegmatites but do not exclude other models for early-stage pegmatite evolution. The chemical and textural features of columbite-tantalite and cassiterite in the Leinster albite-spodumene pegmatites are seen in similar rare element pegmatites and rare metal granites elsewhere, suggesting wide applicability of the processes interpreted for Leinster.Late-stage processes of the type that affected the lithium pegmatites at Leinster may either enhance or reduce economic potential: ore metal tenor may be increased because late-stage columbite-tantalite is generally richer in Ta, and/or ore metals may be lost from pegmatites to country rocks. Lithium pegmatites, including the ones at Leinster, are commonly associated spatially with Sn-W veins and greisens and share some geochemical and textural features, such as evidence of widespread albitization. We propose that lithium pegmatites are transitional products regarding the interrelated dimensions time, temperature, and depth in S-type granite-related Li-Sn-W mineralizing systems.

中文翻译：

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东南爱尔兰锂伟晶岩中的交代高场强元素，锡和贱金属富集过程

与平均地壳丰度相比，包括Zr，Nb，Hf，Ta和U在内的高场强元素（HFSE）通常富含稀有元素伟晶岩。阿尔比特辉石辉晶岩可能与锡一起显示出这些元素的经济等级，主要存在于氧化物矿物中。人们对这些岩石中导致HFSE富集和沉淀的过程的了解还很少。在这里，我们描述了伦斯特钠长石-锂辉石伟晶岩中HFSE，锡和贱金属的矿物的质地和地球化学特征。我们使用这些数据来推断伟晶岩结晶过程中这些金属的富集和沉淀过程，尤其是亚固相过程。伦斯特钠长石-锂辉石伟晶石位于加里东S型伦斯特岩基岩东部东南侧的东卡洛变形带内。爱尔兰。这些伟晶岩的最终结晶阶段以自成岩作用和热液叠印为特征，从而导致原地的greisenization和大量块状，通常是取代的方铁矿沉淀。在这些后期，锡石和HFSE矿物（（钴铁矿和锆石）主要结晶。在岩浆早期阶段沉淀的HFSE矿物晶体通常显示出在后期阶段吸收和额外生长的证据。其他的，例如微晶石和尿石，仅在交代过程中或从热液中结晶。贱金属硫化物是这些流体中最后的沉淀物。我们给出了伦斯特钠长石-锂辉石伟晶石的详细共生序列，并表明后期水性流体可输送HFSE，特别是在所有熔体结晶之后。钽的富集似乎已经受到影响整个结晶介质的过程的控制，这与哥伦比-钽铁矿的分步结晶相反。当前和我们以前的工作中描述的质地和共生现象可以通过共存液体之间的元素分配得到很好的解释，其特征与已发表的稀有元素伟晶岩的熔体-流体不溶混模型相似，但不排除其他早期模型伟晶岩演化。在其他类似的稀有元素伟晶岩和稀有金属花岗岩中也可以看到伦斯特钠长石-锂辉石伟晶岩中的钴铁矿-钽铁矿和锡石的化学和质地特征，这表明该方法在莱恩斯特解释中具有广泛的适用性。影响伦斯特锂伟晶岩类型的后期过程可能会增强或降低经济潜力：矿石金属的年期可能会增加，因为后期的lum钴钽铁矿通常富含Ta，和/或矿石金属可能因伟晶岩到乡村岩石。锂伟晶岩，包括在伦斯特的伟晶岩，通常在空间上与Sn-W脉和greisens关联，并具有一些地球化学和质地特征，例如广泛的阿尔比特化的证据。我们建议锂伟晶岩是过渡产品，涉及与S型花岗岩相关的Li-Sn-W矿化系统中相互关联的时间，温度和深度。矿石金属的年期可能会增加，因为后期的钴铁矿-钽铁矿通常富含Ta，并且/或者矿石金属可能会从伟晶岩流失到乡村岩石中。锂伟晶岩，包括在伦斯特的伟晶岩，通常在空间上与Sn-W脉和greisens关联，并具有一些地球化学和质地特征，例如广泛的阿尔比特化的证据。我们建议锂伟晶岩是过渡产品，涉及与S型花岗岩相关的Li-Sn-W矿化系统中相互关联的时间，温度和深度。矿石金属的年期可能会增加，因为后期的钴铁矿-钽铁矿通常富含Ta，并且/或者矿石金属可能会从伟晶岩流失到乡村岩石中。锂伟晶岩，包括在伦斯特的伟晶岩，通常在空间上与Sn-W脉和greisens关联，并具有一些地球化学和质地特征，例如广泛的阿尔比特化的证据。我们建议锂伟晶岩是过渡产品，涉及与S型花岗岩相关的Li-Sn-W矿化系统中相互关联的时间，温度和深度。