We provide new constraints for the fluid flow system at the origin of two F-Ba deposits located at the unconformity between the south of the Paris Basin and the northern edge of the French Massif Central. We used microthermometry and bulk crush-leach analyses to determine isotope ratios of mineralizing fluids (δ¹⁸O, δD, δ³⁷Cl), together with cation and anion composition of fluid inclusions hosted by fluorite. Chlorinity and Cl/Br molar ratios (212–521) indicate the involvement of a brine, whose origin likely corresponds to Triassic evaporated seawater compatible with supratidal dolomitic facies preserved nearby. Microthermometry reveals high Ca/Na ratios, suggesting that the brine composition evolved from hydrothermal alteration of the Variscan basement and partial dissolution and replacement of the host sedimentary rocks. δ³⁷Cl values are lower than the expected value of evaporated seawater, suggesting Cl isotope fractionation by ion filtration in clay-rich horizons. Fluorite crystallized at minimum temperatures of 70 to 110 °C, 10–40 °C warmer than the host Triassic sedimentary rocks. Ascending brines were expelled during the Early Cretaceous and experienced a drop in pressure and temperature, together with possible mixing with the SO₄-rich pore water of the sedimentary rocks, causing precipitation of silica, followed by fluorite and barite, forming a stratabound deposit similar to those found in many areas in Western Europe.

我们为位于巴黎盆地南部和法国中央高原北缘之间不整合面的两个 F-Ba 沉积物起源处的流体流动系统提供了新的约束。我们使用显微测温法和批量压碎浸出分析来确定矿化流体的同位素比率（δ ¹⁸ O、δD、δ ³⁷Cl)，以及以萤石为主体的流体包裹体的阳离子和阴离子成分。氯度和 Cl/Br 摩尔比 (212-521) 表明存在卤水，其起源可能对应于三叠纪蒸发海水，与附近保存的潮上白云岩相相一致。显微测温显示高 Ca/Na 比率，表明盐水成分是由 Variscan 基底的热液蚀变和宿主沉积岩的部分溶解和替换演化而来。δ37 ^_Cl 值低于蒸发海水的预期值，表明在富含粘土的地层中通过离子过滤进行 Cl 同位素分馏。萤石在最低温度 70 至 110 °C 下结晶，比三叠纪沉积岩高 10–40 °C。早白垩世，上升的卤水被排出，经历了压力和温度的下降，并且可能与沉积岩中富含SO ₄的孔隙水混合，导致二氧化硅沉淀，随后是萤石和重晶石，形成类似的层控沉积物。西欧许多地区发现的那些。