Basin scale evolution of zebra textures in fault-controlled, hydrothermal dolomite bodies: Insights from the Western Canadian Sedimentary Basin
Basin scale evolution of zebra textures in fault-controlled, hydrothermal dolomite bodies: Insights from the Western Canadian Sedimentary Basin
复制标题
断层控制的热液白云岩体中斑马纹理的盆地尺度演化：来自加拿大西部沉积盆地的见解
DOI：
10.1111/bre.12789
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发表时间：
2023
期刊：
影响因子：
3.2
通讯作者：
McCormick C
中科院分区：
文献类型：
--
作者：
McCormick C
构造控制的白云化作用通常涉及高压(P)、高温(T)流体与围岩的相互作用。这种反应通常伴随着胶结和再结晶，由此产生的热液白云岩（HTD）体包括几种“诊断”岩石结构。斑马纹理，与盒状纹理和白云岩角砾岩相关联，被广泛认为反映了这些升高的P/T条件。尽管已经提出了一系列概念模型来解释这些岩石结构的成因，但控制其时空演化的过程仍然知之甚少。通过对加拿大西部沉积盆地中寒武系地层中HTD体的详细岩石学和地球化学分析，表明单一成因模型不能适用于这些岩石结构的所有特征。相反，一系列广泛的沉积学、构造和交代过程有助于它们的形成；在流域尺度上，每一个都是时空变化的。在流体源的远端，白云化主要是层控的，包括替代白云岩、层理平行斑马结构和罕见的白云岩角砾岩（非层控的，仅位于断层的近端）。白云化越来越趋向于非层控，靠近流体源，包括层理倾斜的斑马织构、箱形织构和受重结晶影响的白云岩角砾岩。岩石学和地球化学证据表明，这些岩石结构是由鞍状白云岩作为胶结物的扩张破裂、角化和沉淀形成的，但在白云化后期发生了明显的再结晶作用。这些岩石结构与断层和碳酸盐岩矿床（如菱镁矿、稀土元素和密西西比河谷型矿化）密切相关，因此提供了关于高P/T条件下流体通量和碳酸盐岩交代作用的宝贵信息。
Structurally controlled dolomitization typically involves the interaction of high‐pressure (P), high‐temperature (T) fluids with the surrounding host rock. Such reactions are often accompanied by cementation and recrystallization, with the resulting hydrothermal dolomite (HTD) bodies including several ‘diagnostic’ rock textures. Zebra textures, associated with boxwork textures and dolomite breccias, are widely considered to reflect these elevated P/T conditions. Although a range of conceptual models have been proposed to explain the genesis of these rock textures, the processes that control their spatial and temporal evolution are still poorly understood. Through the detailed petrographical and geochemical analysis of HTD bodies, hosted in the Middle Cambrian strata in the Western Canadian Sedimentary Basin, this study demonstrates that a single genetic model cannot be applied to all the characteristics of these rock textures. Instead, a wide array of sedimentological, tectonic and metasomatic processes contribute to their formation; each of which is spatially and temporally variable at the basin scale. Distal to the fluid source, dolomitization is largely stratabound, comprising replacement dolomite, bedding‐parallel zebra textures and rare dolomite breccias (non‐stratabound, located only proximal to faults). Dolomitization is increasingly non‐stratabound with proximity to the fluid source, comprising bedding‐inclined zebra textures, boxwork textures and dolomite breccias that have been affected by recrystallization. Petrographical and geochemical evidence suggests that these rock textures were initiated due to dilatational fracturing, brecciation and precipitation of saddle dolomite as a cement, but significant recrystallization occurred during the later stages of dolomitization. These rock textures are closely associated with faults and carbonate‐hosted ore deposits (e.g. magnesite, rare earth element and Mississippi Valley–type mineralization), thus providing invaluable information regarding fluid flux and carbonate metasomatism under elevated P/T conditions.