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Insights into fluid evolution and Re enrichment by mineral micro-analysis and fluid inclusion constraints: Evidence from the Maronia Cu-Mo ± Re ± Au porphyry system in NE Greece
Mineralium Deposita ( IF 4.8 ) Pub Date : 2024-05-04 , DOI: 10.1007/s00126-024-01273-4
Jan J. Falkenberg , Manuel Keith , Vasilios Melfos , Max Hohl , Karsten M. Haase , Panagiotis Voudouris , Alica Höss , Julia Wenske , Reiner Klemd , Christoph Beier , Martin Kutzschbach , Harald Strauss

Porphyry-epithermal veins hosting Re-rich molybdenite and rheniite (ReS2) from the Maronia Cu-Mo ± Re ± Au porphyry in Thrace, NE Greece, provide new insights into the hydrothermal processes causing extreme Re enrichment. Quartz trace element chemistry (Al/Ti, Ge/Ti), Ti-in-quartz thermometry, and cathodoluminescence imaging reveal multiple quartz generations in consecutive hydrothermal quartz-sulfide veins associated with potassic, sericitic, and argillic alteration. Fluid inclusions in different quartz generations indicate that phase separation and fluid cooling are the main ore-forming processes in the porphyry stage (~ 500 – 350 °C), whereas mixing of a vapor-rich fluid with metalliferous (e.g., Pb, Zn, Au) meteoric water forms the epithermal veins (~ 280 °C). These processes are recorded by trace element ratios in pyrite that are sensitive to changes in fluid temperature (Se/Te), fluid salinity (As/Sb, Co/As), and mixing between fluids of magmatic and meteoric origin (Se/Ge). Highly variable intra-grain δ34S values in pyrite record S isotope fractionation during SO2 disproportionation and phase separation, emphasizing the importance of in situ δ34S analysis to unravel ore-forming processes. High δ34S (~ 4.5‰) values of sulfides are indicative of low SO42−/H2S fluid ratios buffered by the local host rocks and mixing of the magma-derived fluid with meteoric water. The formation of Re-rich molybdenite (~ 6600 ppm) is favored by cooling and reduction of a magma-derived, high-temperature (~400 °C), oxidized, and Re-rich fluid triggering efficient Re precipitation in early veins in the potassic alteration zone. The systematic temporal fluid evolution therefore reveals that coeval cooling and reduction of oxidized Re-rich fluids cause extreme Re enrichment at the Maronia porphyry system.



中文翻译:

通过矿物微分析和流体包裹体约束深入了解流体演化和铼富集:来自希腊东北部 Maronia Cu-Mo ± Re ± Au 斑岩系统的证据

希腊东北部色雷斯 Maronia Cu-Mo ± Re ± Au 斑岩中含有富含 Re 的辉钼矿和铼铁矿 (ReS 2 ) 的斑岩-浅成热液脉,为了解导致 Re 极端富集的热液过程提供了新的见解。石英微量元素化学(Al/Ti、Ge/Ti)、石英中钛测温和阴极发光成像揭示了与钾质、绢云母和泥质蚀变相关的连续热液石英硫化物脉中的多个石英世代。不同石英世代中的流体包裹体表明,相分离和流体冷却是斑岩阶段(~ 500 – 350 °C)的主要成矿过程,而富含蒸气的流体与金属(例如,Pb、Zn、 Au) 大气水形成浅热液脉 (~ 280 °C)。这些过程通过黄铁矿中的微量元素比率记录,这些元素比率对流体温度 (Se/Te)、流体盐度 (As/Sb、Co/As) 以及岩浆和大气成因流体 (Se/Ge) 之间的混合敏感。 。黄铁矿中高度可变的晶内 δ 34 S 值记录了 SO 2歧化和相分离过程中的 S 同位素分馏,强调了原位 δ 34 S 分析对于揭示成矿过程的重要性。硫化物的高 δ 34 S (~ 4.5‰) 值表明由当地主岩缓冲的低 SO 4 2− /H 2 S 流体比率以及岩浆衍生流体与大气水的混合。岩浆衍生的高温(~400°C)、氧化和富稀土流体的冷却和还原有利于富稀土辉钼矿(〜6600 ppm)的形成,从而在早期矿脉中触发有效的铼沉淀。钾蚀变带。因此,系统的时间流体演化表明,同时冷却和氧化富Re流体的还原导致了Maronia斑岩系统Re的极度富集。

更新日期:2024-05-08
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