The Meillon (Callovo-Oxfordian) and Mano (Tithonian) Formations are dolomitized carbonate reservoirs that actively produce oil and gas (Aquitaine Basin, France). In this study, the dolomitization conditions of their counterparts exhumed in the northwestern Pyrenees are detailed using a combination of field observations, petrography, fluid inclusion microthermometry, elemental and isotopic geochemistry, and carbonate U–Pb geochronology. Dolomitization occurred in several stages spanning from the Neocomian (pre-rift) to the Albian (syn-rift, associated with mantle exhumation and active salt tectonics). Both formations were first massively dolomitized in near-surface to shallow burial conditions during the Berriasian-Valanginian, likely triggered by the influx of marine-derived waters. Between the Barremian and the Albian, the Early Cretaceous rifting caused the upward influx of hot fluids associated with the partial to complete recrystallization of the initial dolomites. During the Albian, subsequent dolomites precipitated in both formations as high-temperature (T > 160 °C) vein- and pore-filling cement. Distinct fluid inclusion chlorinities and rare earth element patterns between the Meillon and Mano Formations point to fluid compartmentalization during this stage. Whereas dolomite cements indicate the involvement of evaporite-derived brines in the Meillon Formation, precipitation was likely related to clay-derived water in the Mano Formation. Lastly, a final episode of dolomite cementation occurred only in the vicinity of faults and volcanic intrusions during the Albian when the highest temperatures were recorded in both formations (T > 250 °C). These saddle dolomites precipitated from hydrothermal water with a mixture of mantle-, crustal-, and evaporite-derived waters channeled by faults and active diapirs. Subsequent quartz and calcite cement precipitation reveals a temperature decrease in a post-rift to inversion setting (post-Cenomanian) and indicates fluid compartmentalization between both formations. This study highlights the major control exerted by rifting, combined with the presence of diapiric salt, on dolomitization, making carbonate platforms of modern salt-rich passive margins potential targets for exploration.

Meillon（Callovo-Oxfordian）和Mano（Tithonian）地层是白云石化的碳酸盐岩油藏，活跃地生产石油和天然气（法国阿基坦盆地）。在这项研究中，结合了野外观察，岩相学，流体包裹体热计量法，元素和同位素地球化学以及碳酸盐U–Pb年代学，详细介绍了比利牛斯山西北部的白云石化条件。从新科纪（裂谷前）到阿尔比亚（同裂谷，与地幔掘出和活跃的盐构造有关），白云石化发生了多个阶段。这两个岩层首先在贝里亚斯-瓦朗吉人时期从近地表到浅埋的条件下被大量白云石化，这很可能是由于海洋水的涌入引起的。在巴雷米亚人和阿尔比人之间，白垩纪早期裂谷导致热流体向上涌入，与初始白云岩的部分完全重结晶有关。在Albian期间，随后的白云石在这两个地层中沉淀为高温（T> 160°C）的静脉和孔隙填充水泥。Meillon和Mano地层之间明显的流体包裹体氯含量和稀土元素形态表明，在这一阶段，流体的分隔作用。尽管白云石胶结物表明梅隆组中有蒸发岩衍生的卤水，但马诺组中的沉淀可能与黏土衍生的水有关。最后，白云石胶结作用的最后一次发生仅在阿尔比亚时期断层和火山侵入附近，这两个地层均记录到最高温度（T> 250°C）。这些鞍状白云石是从热水中沉淀出来的，其中混合了由地幔，地壳和蒸发岩衍生的水，这些水由断层和活跃的底辟引导。随后的石英和方解石水泥沉淀表明，在裂谷后至反演环境（后塞曼期）中温度降低，并表明两种地层之间的流体分隔。这项研究强调了裂谷作用的主要控制作用，并结合了双api盐对白云石化作用的影响，使现代富含盐的被动边缘碳酸盐岩平台成为勘探的潜在目标。随后的石英和方解石水泥沉淀表明，在裂谷后至反演环境（后塞曼后期）中温度下降，并表明两种地层之间的流体分隔。这项研究强调了裂谷作用的主要控制作用，并结合了双api盐对白云石化作用的影响，使现代富含盐的被动边缘碳酸盐岩平台成为勘探的潜在目标。随后的石英和方解石水泥沉淀表明，在裂谷后至反演环境（后塞曼后期）中温度下降，并表明两种地层之间的流体分隔。这项研究强调了裂谷作用的主要控制作用，并结合了双api盐对白云石化作用的影响，使现代富含盐的被动边缘碳酸盐岩平台成为勘探的潜在目标。