关键词: 太行山北段, 紫荆关断裂带, 碎裂岩系列断层岩, 显微构造, 变形叠加

Abstract: The northern segment of the Taihang Mountains is a typical tectonic region located in the middle segment of the Daxing’anling-Taihang-Wuling tectonic belt. Mesozoic and Cenozoic tectonites of cataclasite series developed along the 2 main fault zones in the region: the Zijingguan and Wulonggou Fault zones. Microstructures of these tectonites were studied in detail according to the different lithologies of their host rocks, which may influence the deformation mechanism. Accordingly, the observed geological bodies can be divided into carbonate and granitoid rocks. According to their occurence, microstructures and microscopic deformation mechanism, the tectonites can be divided into cataclased rocks or fault breccias, protocataclasites and cataclasites. Furthermore, three stages of deformation can be distinguished from the superimposition of cataclasis of different stages exposed in these tectonites. The tectonites produced in different stages are different. The product of the first stage cataclasis can be assigned to cataclasite, which is the product of relatively intense deformation. In the second stage, the product was mainly protocataclasites or cataclased rocks, and the deformation shown in the matrices superposed upon the previous one. In the third stage, the pre-existing tectonites was cataclased in a relatively low intensity, and the veins cut into the matrices formed in the earlier stages. By combining the afore-mentioned information with the related geological data, it can be inferred that 3 significant faulting events had occurred on the Zijingguan Fault Zone in Mesozoic and Cenozoic, and each stage of faulting had its own feature, by which a trend line from high to low intensity of deformation can be traced. Three stages of tectonites corresponded with the three stages of significant activity of the fault zone after the emplacement of granitoid intrusions along the Taihang tectonic belt.

Key words: northern segment of the Taihang Mountains, Zijingguan Fault Zone, cataclasite series, tectonite, microstructure, superimposition of deformation