Orogenic processes encompass a complex interplay of deformation and metamorphic events, which can impact the formation of ore deposits to various degrees. However, distinguishing fluid signatures from orogenic versus post-orogenic events presents a significant challenge due to the scarcity of robust geochemical indicators that remain unaffected during multiple post-mineral reworking events. This study carefully examines the properties and chemistry of primary and secondary fluid inclusions (FIs), identifying distinct signatures of two fluid populations linked to different styles of Pb-Zn mineralization in the Pyrenean Axial Zone (PAZ) of Southern-France/Northern-Iberia: These included late-Carboniferous stratabound epigenetic Pb-Zn deposits and Mesozoic crosscutting Pb-Zn(-Ge) vein systems. Population (I) is identified in primary and secondary FIs in a few crosscutting Pb-Zn veins and constitutes a minor component in stratabound epigenetic bodies. It exhibits Na-dominated low to intermediate salinity (< 20 wt% NaCl eq.), intermediate temperatures (200–350 °C), abundant CO₂-rich FIs and shows low homogeneous Cl/Br molar ratios. These characteristics are consistent with a metamorphic origin of the fluids, associated with Late-Variscan metamorphism. Population (II) is commonly observed in the crosscutting vein systems where it occurs as primary and pseudosecondary FIs, as well as in stratabound epigenetic bodies where it represents the main fluid component of secondary FIs. Population (II) is Ca-dominated with intermediate to high salinity (15–35 wt% NaCl eq.), relatively low temperature (< 200 °C), and shows high Cl/Br molar ratios with significant variations. This last characteristic is typical of mixing of at least two fluids, one with a probable low Cl/Br molar ratio at shallow crustal levels and another with high Cl/Br molar ratio at deeper levels. Characteristics of population (II) are consistent with a fluid of basinal origin that interacted with the basement while circulating in the Pyrenees during the Mesozoic, although a Pyrenean-Alpine age cannot be excluded. Locally, in sphalerite-hosted secondary FIs that form trails in the crosscutting veins, we find evidence of high Ge concentrations (up to few 1000s ppm), which correlate with anomalous Pb and Tl concentrations. Very high metal concentrations (up to 1–2 wt% Pb, Zn), which are inversely proportional to Cl/Br molar ratios, are found in FIs mainly within veins hosted in deep-seated high-grade metamorphic rocks. Based on a compilation of fluid data from the literature, a first-order correlation can be deduced between the metamorphic grade of the rocks hosting the mineralization and the Pb and Zn content in the FIs. Early stratabound orebodies are considered likely sources of metal for the development of the late crosscutting vein mineralization. This study demonstrates the significance and complexity of orogen-scale fluid circulation and supports the importance of pre-existing metal enrichment in the crust, especially in high-grade metamorphic rocks as a prerequisite for the formation of Pb-Zn veins in complex multi-stage orogens.

造山过程包括变形和变质事件的复杂相互作用，这会在不同程度上影响矿床的形成。然而，区分流体特征与造山事件和造山后事件是一项重大挑战，因为缺乏强大的地球化学指示剂，这些指示剂在多个矿物后返工事件中不受影响。本研究仔细研究了原生和次生流体包裹体 （FI） 的性质和化学性质，确定了与法国南部/北伊比利亚比利牛斯轴向带 （PAZ） 中不同风格的 Pb-Zn 矿化相关的两种流体群的不同特征：其中包括晚石炭纪层状表生 Pb-Zn 矿床和中生代横切 Pb-Zn（-Ge） 矿脉系统。群体 （I） 在初级和次级 FI 中鉴定在一些交叉 Pb-Zn 矿脉中，并构成层状表观遗传体的次要组成部分。它表现出以 Na 为主的中低盐度 （< 20 wt% NaCl eq.）、中等温度 （200–350 °C）、丰富的富含 CO₂ 的 FI，并显示出低均匀的 Cl/Br 摩尔比。这些特征与流体的变质起源一致，与 Late-Variscan 变质作用有关。群体 （II） 通常存在于横切脉系统中，它作为初级和假次级 FI 出现，以及在分层的表观遗传体中，它代表次级 FI 的主要流体成分。种群 （II） 以 Ca为主，盐度为中高 （15–35 wt% NaCl 当量），温度相对较低 （< 200 °C），并显示出高 Cl/Br 摩尔比，变化显著。 最后一个特征是至少两种流体混合的典型特征，一种在浅地壳层可能具有低 Cl/Br 摩尔比，另一种在较深层具有高 Cl/Br 摩尔比。种群特征 （II） 与中生代在比利牛斯山脉循环时与基底相互作用的盆地起源流体一致，尽管不能排除比利牛斯-阿尔卑斯时代。在当地，在横切矿脉中形成尾迹的闪锌矿赋存的次生 FI 中，我们发现了高 Ge 浓度（高达几 1000 秒 ppm）的证据，这与异常的 Pb 和 Tl 浓度相关。非常高的金属浓度（高达 1-2 wt% Pb、Zn），与 Cl/Br 摩尔比成反比，主要存在于深部高品位变质岩中的矿脉中。根据文献中的流体数据汇编，可以推断出承载矿化体的岩石的变质品位与 FI 中的 Pb 和 Zn 含量之间的一阶相关性。早期层状矿体被认为是晚期横切矿脉矿化发育的可能金属来源。这项研究证明了造山带尺度流体循环的重要性和复杂性，并支持地壳中预先存在的金属富集的重要性，特别是在高品位变质岩中，这是在复杂的多阶段造山带中形成 Pb-Zn 矿脉的先决条件。