甘肃金川矿区古构造应力场恢复及演化研究

金川矿区经历了复杂的构造演化历史，目前其成矿期后的构造变形特征和应力场演化阶段仍缺乏精细剖析。文章运用构造解析方法对金川矿区地表基岩中的断层进行了分期和配套，确定了构造变形序列，认为矿区存在4组重要的断层组合，包括北东向逆冲断层和北西向走滑断层、北东向走滑断层和北西向逆冲断层、北西向正断层以及北东东向走滑断层。通过研究断层破裂面及擦痕构造，利用赤平投影法恢复了断层的古构造应力场，结合区域大地构造演化历史，准确限定了金川矿区成矿期后的应力场演化阶段，对认识区域构造演化和开发新远景区具有重要意义。结果显示，金川矿区在成矿期后经历了4期古构造应力场作用，表现为多阶段不同方向的挤压和伸展过程，分别响应了区域中生代以来的一系列构造热事件，Ⅰ期表现为早—中侏罗世的北西—南东向挤压应力场，Ⅱ期为晚侏罗世的北东—南西向挤压应力场，Ⅲ期为早白垩世的北东—南西向伸展应力场，Ⅳ期为晚白垩世以来的北东—南西向挤压应力场。

Study on the reconstruction of the paleo-tectonic stress field and its evolution in the Jinchuan mining district,Gansu Province,China

The Jinchuan mining district has undergone a complex tectonic evolution history, and detailed analysis of the post-mineralization deformation characteristics and stress field evolution stages needs to be completed. This paper employs structural analysis methods to stage and correlate the faults in the bedrock of the Jinchuan mining district, determining the structural deformation sequence. It identifies four significant fault combinations in the region, including NE-trending thrust faults and NW-trending strike-slip faults, NE-trending strike-slip faults and NW-trending thrust faults, NW-trending normal faults, and NEE-trending strike-slip faults. The paleo-tectonic stress field of fault is reconstructed by using the lower hemisphere stereographic projection method on the base of studying faults and striations. Combining the paleo-tectonic stress field results with the regional tectonic evolution history, the study accurately defines the stress field evolution stages in the Jinchuan mining district after the mineralization period, which is crucial for understanding regional tectonic evolution and the development of new prospective areas. The results indicate that the Jinchuan mining district experienced four phases of paleo-tectonic stress field after the mineralization period, characterized by multi-stage compression or extension in different directions. These phases responds to a series of regional tectonic thermal events since the Mesozoic respectively: Phase I exhibits a NW–SE compression stress field during the early to middle Jurassic (J1-2); Phase II shows a NE–SW compression stress field during the late Jurassic (J3); Phase III reflects a NE–SW extensional stress field during the Early Cretaceous (K1); Phase IV represents a NE–SW compression stress field since the Late Cretaceous (K2).