The Huanghua Depression in the Bohai Bay Basin has experienced significant development of massive NNE-NE faults, influenced by the Eocene activation of the Lanliao Fault and its subsequent Oligocene dextral intensification. These faults serve as a conduit for connate fluid and magmatic hydrothermal fluid (MHF), thereby forming a complex fluid system. Gaining an understanding of these fluid activities is essential for research into mass balance and hydrocarbon migration within shales. This study explores the origin and distribution of analcime, aligns the fluid evolution stage with different analcime types, and constructs a comprehensive water-rock reaction sequence. The study identifies six types of analcime based on occurrence characteristics (occurring as laminae, lens, fracture filling, bioshell filling, vein marginal crystal and cement). The above six types of analcime is further classified into hydrothermal fluid origin analcime (HFOA: include analcime cement, vein marginal crystal, lens, fracture filling and bioshell filling) and connate fluid origin analcime (CFOA: analcime laminae) based on major elemental indicators (Si/Al and 10K/(10K + Na)). HFOA has lower ∑REE (rare earth element) and strong positive correlation between ∑REE and LILEs (large ionic lithophilic elements); while CFOA has higher ∑REE and weak positive correlation between ∑REE and LILEs. Different analcime types correlate with varying fluid properties and transport stages. HFOA forms during MHF upwelling. After the MHF entering and mixing with the lake water, thermal repulsions between the crystal particles made it move to form fine-grained sedimentary layer, the connate fluid trapped in pores directly precipitate to form CFOA, or form CFOA by modifying clay minerals and feldspars. Considering the tectonic context, we infer that the formation of analcime was primarily driven by high-frequency, low-intensity magmatism, governed by the activation of Lanliao deep fault. The study of analcime can aid in identifying and classifying fluid activity processes, offering a novel perspective for investigating sedimentation and diagenesis in continental shales.

中文翻译：

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断陷湖盆页岩微米级流体示踪与演化：方沸石原位分析的证据与约束

渤海湾盆地黄骅坳陷受兰辽断裂始新世活化及其随后的渐新世右旋强化影响，经历了北北东-北东向大型断裂的显着发育。这些断层充当原生流体和岩浆热液（MHF）的通道，从而形成复杂的流体系统。了解这些流体活动对于研究页岩内的质量平衡和碳氢化合物运移至关重要。本研究探讨了方沸石的起源和分布，将流体演化阶段与不同的方沸石类型相结合，并构建了全面的水岩反应序列。该研究根据赋存特征（以薄层、透镜体、裂缝充填物、生物壳充填物、脉边缘晶体和胶结物的形式出现）确定了六种类型的方沸石。上述六类方沸石根据主要元素指标进一步分为热液成因方沸石（HFOA：包括方沸石胶结物、脉缘晶体、透镜体、裂缝充填物和生物壳充填物）和原生流体成因方沸石（CFOA：方沸石纹层）。 Si/Al 和 10K/(10K + Na))。 HFOA具有较低的ΣREE（稀土元素），并且ΣREE与LILEs（大离子亲石元素）呈强正相关性；而 CFOA 的 ΣREE 较高，ΣREE 与 LILE 之间的正相关性较弱。不同的方沸石类型与不同的流体特性和运输阶段相关。 HFOA 在 MHF 上升流期间形成。 MHF进入并与湖水混合后，晶体颗粒之间的热斥力使其移动形成细粒沉积层，截留在孔隙中的原生流体直接沉淀形成CFOA，或通过改性粘土矿物和长石形成CFOA。考虑到构造背景，我们推断方沸石的形成主要是由高频、低强度的岩浆作用驱动的，受兰辽深断裂的激活控制。方沸石的研究有助于识别和分类流体活动过程，为研究大陆页岩的沉积和成岩作用提供了新的视角。