ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    秦岭成矿带金成矿规律及资源潜力

    Gold Metallogenic Regularity and Resource Potential in the Qinling Metallogenic Belt

    • 摘要:
      目的 秦岭成矿带是中国重要的金多金属成矿带,也是中国仅次于胶东的第二大金成矿带。近年来在早子沟等众多矿床中取得了找矿新突破,亟需对其金成矿规律与资源潜力进行深入研究。
      方法 笔者通过对带内地层、构造、岩浆岩、地球物理–地球化学特征以及613处金矿床(点)成矿背景、矿化特征和控矿要素的梳理,揭示秦岭成矿带金矿分布具有“北西成行、北东成串”空间分布特征,认为大型金矿床往往发育在NW向和NE向构造交汇及岩浆作用发育部位。
      结果和结论 东、西秦岭金成矿作用具有明显差异:西秦岭多数金矿赋存于泥盆系、二叠系和三叠系,金成矿作用集中于250~230  Ma与225~210  Ma,与同期岩浆活动关系密切,成矿类型包括变质碎屑岩中热液型与岩浆热液型;东秦岭金矿多赋存于太古宇太华群、寒武系与泥盆系,金成矿时代主要为145~110  Ma,金矿类型以岩浆热液型为主。深部结构上,西秦岭在青藏高原扩张影响下表现为地壳解耦,其深部岩浆通道控制了金矿集区的分布,而东秦岭主要在古太平洋板块影响下出现壳幔贯通的高导体,与燕山期成矿作用关系密切。通过综合对比,笔者在秦岭成矿带划分出25个Ⅳ级金成矿亚带以及10个金成矿系列,其中印支期与中酸性岩浆侵入有关及燕山期与岩浆–热液活动有关的两个金多金属成矿系列最为重要。综合地质矿产、地球物理和地球化学多元信息,圈定秦岭成矿带金找矿远景区73处(28个I类、34个Ⅱ类和11个Ⅲ类)。基于上述成矿规律与资源潜力综合评价,西秦岭应以夏河–合作、寨上–李坝矿集区为重点,开展矿床深边部及外围找矿工作;在花崖沟–九条沟、凤太等找矿远景区加强勘查工作;对文县–康县矿集区应重点关注与岩浆–热液作用有关隐伏矿体的寻找。东秦岭地区需加强综合地球物理技术在深部找矿中的应用,小秦岭矿集区应重视深部找矿工作,同时重点关注夏家店、刘家峡、苏岭沟等已知矿床的深部及外围找矿。

       

      Abstract:
      Objective The Qinling metallogenic belt is one of China’s most important Au–polymetallic metallogenic belts and the country’s second-largest Au-metallogenic belt after Jiaodong. In recent years, new breakthroughs have been achieved in many deposits such as Zaozigou, creating an urgent need for in-depth research on its Au-metallogenic regularities and resource potential.
      Methods Based on a systematic review of strata, structures, magmatism, geophysical–geochemical characteristics, and the metallogenic setting, mineralization features, and ore-controlling factors of 613 Au deposits (or occurrences) within the belt, this study reveals that Au deposits in the Qinling metallogenic belt display a spatial pattern of “NW-trending belts and NE-trending clusters.” Large Au deposits commonly occur at the intersections of NW- and NE-trending structures and in areas with intense magmatic activity.
      Results and Conclusion  The Au metallogenesis of the eastern and western Qinling exhibits significant differences. In western Qinling, most Au deposits are hosted in the Devonian, Permian, and Triassic strata, with mineralization ages concentrated at 250~230 Ma and 225~210 Ma, closely related to contemporaneous magmatism. Metallogenic types include hydrothermal type hosted in metamorphosed clastic rocks and magmatic-hydrothermal type. In eastern Qinling, Au deposits are mainly hosted in the Archean Taihua Group, the Cambrian, and the Devonian strata, with mineralization ages primarily between 145 and 110 Ma. Their metallogenic type is mainly magmatic-hydrothermal type. For crustal structure, western Qinling shows crustal decoupling influenced by the expansion of the Tibetan Plateau, with deep magmatic channels controlling the distribution of Au deposit districts. In contrast, eastern Qinling exhibits high-conductivity crust–mantle penetrating structures influenced by the Paleo-Pacific Plate, contributing to the Yanshanian metallogenesis. Through comprehensive comparison, this study delineates 25 fourth-order Au metallogenic sub-belts and 10 Au metallogenic series within the Qinling metallogenic belt. Among these, the two most important series are the Indosinian series related to intermediate–felsic magmatic intrusions and the Yanshanian series associated with magmatic–hydrothermal activity. Integrating geological, geophysical, and geochemical information, 73 prospective Au exploration targets are identified within the Qinling metallogenic belt (28 Class I, 34 Class II, and 11 Class III). Based on the metallogenic regularities and resource-potential assessment, It is suggested that exploration in western Qinling should focus on the Xiahe–Hezuo and Zhaishang–Liba ore districts, targeting the deep and peripheral zones of existing deposits. In addition, exploration should also be strengthened in Huayagou–Jiutiaogou, FengTai, and other prospective areas, and particular attention should be given to concealed orebodies related to magmatic-hydrothermal activity in the Wenxian–Kangxian ore district. In eastern Qinling, the application of integrated geophysical techniques should be enhanced for deep-level exploration. Deep exploration should be prioritized in the Xiaoqinling ore district, with special attention to deep and peripheral zones of known deposits such as Xiajiadian, Liujiaxia, and Sulinggou.

       

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