The southeastern French Massif Central represents an ideal area to study the linkage between regional metamorphism, crustal partial melting, emplacement of granitic magmas, and hydrothermal Sn-W mineralization in a polyphase tectono-metamorphic setting related to the late-Variscan orogeny. Here, we describe the mineralogical, structural, geochemical, and geochronological characteristics of cassiterite–wolframite-bearing quartz veins at St-Mélany, a small uneconomic Sn-W occurrence located in the North Cévennes area. The veins show evidence of ductile deformation (boudinage, asymmetric folding, dynamic recrystallization) consistent with a synkinematic emplacement during the regional low-pressure–medium-temperature metamorphism at ca. 320–315 Ma. This dominantly water-fluxed melting event reaching muscovite breakdown conditions (T < 750 °C, P ≈ 0.6 GPa) was synchronous to the emplacement of the syntectonic Rocles peraluminous granite, which is interpreted as a proximal source for the mineralizing fluids at St-Mélany. The U–Pb LA-ICP-MS dating of coexisting wolframite and cassiterite from a mineralized quartz vein yielded lower-intercept ages of 318.4 ± 2.2 Ma and 311.4 ± 1.0 Ma (2σ), respectively. These results suggest a temporal decoupling of W and Sn mineralization with a time gap of 4–10 Myr, but additional work is needed to confirm this interpretation. A weighted mean ⁴⁰Ar/³⁹Ar date of 304.5 ± 4.8 Ma (2σ) was obtained for muscovite from the selvage of a mineralized vein, interpreted as a recrystallization age related to metamorphic re-equilibration or hydrothermal overprinting. Dikes of aplites and pegmatites cut the Sn-W-mineralized veins and were emplaced at 305.9 ± 3.9 Ma (2σ) based on U–Pb LA-ICP-MS dating of magmatic cassiterite. The dikes have highly evolved compositions typical of peraluminous high-phosphorus rare metal granites with Li-F-Ta > Nb-Sn-Be enrichments. Emplacement of the granitic dikes was coeval with the regional low-pressure–high-temperature metamorphism at ca. 305–300 Ma, reaching biotite dehydration melting conditions (T > 800 °C, P ≈ 0.4 GPa), which led to the formation of the Velay anatectic dome possibly linked to lower crust granulitization. We conclude that polyphase emplacement of W-Sn-mineralized veins at ca. 320–310 Ma and rare metal granitic dikes at ca. 305 Ma results from contrasting crustal melting conditions, in relation to the late-Carboniferous orogenic evolution of the southeastern French Massif Central, and possibly related to delamination of the subcontinental lithospheric mantle.

法国东南部中央高原是研究与晚瓦里西亚造山运动有关的多相构造变质背景中区域变质作用、地壳部分熔融、花岗岩岩浆侵位和热液锡钨矿化之间联系的理想地区。在这里，我们描述了圣梅兰尼 (St-Mélany) 含锡石-黑钨矿石英脉的矿物学、结构、地球化学和地质年代学特征，圣梅兰尼是位于北塞文地区的一个小型不经济的锡钨矿点。这些矿脉显示出延性变形（布丁纳奇、不对称折叠、动态重结晶）的证据，与大约 10 世纪区域低压-中温变质作用期间的同运动就位一致。320–315 Ma。这种主要是水助熔的熔化事件达到了白云母分解条件（T  < 750 °C，P  ≈ 0.6 GPa）与同构造 Rocles 过铝质花岗岩的侵位同步，这被解释为 St-Mélany 矿化流体的近源。对矿化石英脉中共存的黑钨矿和锡石进行 U-Pb LA-ICP-MS 测年，得出的低截距年龄分别为 318.4 ± 2.2 Ma 和 311.4 ± 1.0 Ma (2 σ )。这些结果表明 W 和 Sn 矿化的时间脱钩，时间间隔为 4-10 Myr，但需要额外的工作来证实这一解释。加权平均⁴⁰ Ar/ ³⁹ Ar 日期为 304.5 ± 4.8 Ma (2 σ）是从矿化脉边缘获得的白云母，解释为与变质再平衡或热液叠印相关的重结晶年龄。根据岩浆锡石的U-Pb LA-ICP-MS 测年，细长岩和伟晶岩岩脉切割了 Sn-W 矿化脉，并位于 305.9 ± 3.9 Ma (2 σ ) 处。这些岩脉具有典型的高铝高磷稀有金属花岗岩的高度演化成分，且富集 Li-F-Ta > Nb-Sn-Be。花岗岩岩脉的侵位与约 1997 年区域性低压高温变质作用同时发生。305–300 Ma，达到黑云母脱水熔融条件（T  > 800 °C，P ≈ 0.4 GPa），这导致了韦莱深熔穹顶的形成，可能与下地壳粒岩化有关。我们得出结论，W-Sn 矿化脉的多相侵位大约在 约 320–310 Ma 和稀有金属花岗岩岩脉。305Ma是地壳熔融条件对比的结果，与法国中央地块东南部的晚石炭世造山演化有关，也可能与次大陆岩石圈地幔的分层有关。