Large-scale Ductile Shearing Belt in the Southern Beishan Area of Gansu, China

More than 30 years ago, I published a paper titled "Large-scale East-West Regional Shearing in the Southern Belt of the Beishan Area, Gansu" ("Northwest Geology", 1990, No. 4, pp. 10–12). In this article—drawing upon firsthand data derived from my own fieldwork observations—I explicitly proposed that the southern belt of the Beishan area in Gansu, China (spanning 60 kilometers in width and exceeding 55 kilometers in length) had undergone at least two distinct phases of large-scale regional strike-slip shearing. The first phase involved ductile shearing, while the second consisted of superimposed brittle shearing; both phases were sinistral in nature, occurred subsequent to the Early Permian epoch, and exerted a controlling influence on mineralization in the region. This perspective challenged the prevailing conventional wisdom of the time, which held that the region was subject solely to north-south compressional forces. I am unsure of the ultimate extent of the impact my article may have had; however, numerous subsequent studies have further substantiated the finding that the major gold deposits discovered in this region are structurally controlled by these ductile shear zones. This ductile shear zone continues to harbor many unsolved mysteries; moreover, given its significant value for understanding regional geological evolution and for mineral resource prediction, it could potentially serve as a quintessential case study for mineralization models—making it a worthy subject for exploration by aspiring researchers.

我在30多年前发表过一篇题为《甘肃北山南带的东西向大型区域剪切作用》的论文（《西北地质》1990年第4期，pp.10-12）。在这篇文章中，根据本人野外观察所得的第一手资料明确提出，甘肃北山南带（宽60千米，长度超过55千米）至少发生过两期大型的区域性走向剪切作用，其中第一期为韧性剪切作用，第二期为叠加的脆性剪切作用，两期均为左旋式剪切，活动时间晚于早二叠世，对该区域的成矿有控制作用。这一观点打破了当时认为该地区仅受南北向挤压作用的传统认识。我不知道我的这篇文章最终产生过多大影响，但此后有许多研究进一步证实，该区域发现的大型金矿都与韧性剪切带的构造控制有关。这个韧性剪切带至今仍有许多未解谜题，又对区域地质演化和矿产预测有重要价值，或许还可成为典型的成矿范例研究，值得有志者探索。