Abstract Lithologies and microstructures of fault rocks from the Khao Kho Fault in Thailand are investigated to understand fault behavior and underlying deformation mechanisms. Fault gouges in the shear zone are mainly composed of kaolinite, illite-mica, and illite-smectite and exhibit weak preferred orientation, ranging from 1.2 to 2.3 m.r.d. These fault cores are characterized by high localized strain and intense deformation due to cataclasis and frictional granular flow mechanisms, which produce transgranular fractures, rounded quartz grains, and an ultrafine clay matrix. In contrast, wall rocks show stronger clay preferred orientation, up to 3.9 m.r.d., despite having less clay content than the fault gouges. Much larger fault-related bent and sheared clay grains are present in the wall rocks, suggesting less severe deformation. The discrepancy between fault cores and wall rocks indicate that the development of fabrics is related to faulting and authigenic processes. Weak fabrics in the slip zone are attributed to the comminution of grains and neomineralization, allowing clay platelets to grow and rotate in many directions. In addition, the abundance of metal oxides indicates extensive, multiple fluid alteration processes, which further influence microstructures and fault properties.

中文翻译：

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泰国考科断层微观构造演化与变形机制

摘要 研究了泰国考科断层断层岩的岩性和微观结构，以了解断层行为和潜在的变形机制。剪切带断层泥主要由高岭石、伊利石-云母和伊利石-蒙脱石组成，择优取向弱，范围为1.2～2.3mrd。流动机制，产生穿晶裂缝、圆形石英颗粒和超细粘土基质。相比之下，围岩显示出更强的粘土优先取向，高达 3.9 mrd，尽管粘土含量低于断层泥。围岩中存在更大的断层相关的弯曲和剪切粘土颗粒，表明变形不那么严重。断层核与围岩的差异表明构造发育与断层作用和自生过程有关。滑移区的脆弱织物归因于颗粒的粉碎和新矿化，使粘土片在许多方向上生长和旋转。此外，丰富的金属氧化物表明存在广泛的、多重流体蚀变过程，这进一步影响了微观结构和断层特性。