太行山北段中新生代断层岩的显微构造研究

太行山北段是大兴安岭 -太行山 -武陵山构造带中段的典型构造区 ,区内 2条主断裂 (紫荆关断裂和乌龙沟断裂 )组成的断裂带发育中、新生代的碎裂岩系列断层岩。通过对断裂带内不同岩性原岩区的断层岩进行详细的显微构造研究 ,分析了 3种主要变形强度类型的断层岩 (碎裂化岩石或构造角砾岩、初碎裂岩、碎裂岩 )的区域分布、显微结构以及微观变形机制 ,鉴定出断层岩中的 3期构造变形叠加 ,结合区域资料探讨了区内中、新生代断层岩反映的 3期主要构造运动及其特征 ,显示出构造强度逐渐减弱的演化趋势

MICROSTRUCTURAL ANALYSIS OF MESO-CENOZOIC TECTONITES IN THE NORTHERN SEGMENT OF THE TAIHANG MOUNTAINS

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.