| 西秦岭拉古河金矿床矿化地质特征、矿床成因及勘查指示 |
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| 引用本文：付男,李登榜,李浩.2026.西秦岭拉古河金矿床矿化地质特征、矿床成因及勘查指示[J].地球学报,47(5):1061-1078. |
| DOI：10.3975/cagsb.2026.073002 |
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| 基金项目:本文由深地国家科技重大专项(编号: 2025ZD1009600)资助。 |
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| 中文摘要:拉古河金矿是西秦岭造山带中段夏河—合作地区新发现的大型微细浸染型金矿床, 其矿化特征与成因研究对认识区域金成矿规律及指导找矿勘查具有重要意义。本文在系统查明矿床矿化地质特征的基础上, 结合岩相学与矿相学观察、黄铁矿微区化学成分分析以及容矿花岗闪长斑岩的锆石U-Pb年代学数据, 探讨了该矿床的成因机制及其对区域找矿的指示意义。研究结果表明, 拉古河金矿受断裂控制, 矿体呈脉状、透镜状, 金主要以不可见金形式赋存于含砷黄铁矿和毒砂中, 呈微细浸染状分布于花岗闪长斑岩、岩屑长石砂岩及粉砂质板岩内, 可见极少量自然金。围岩蚀变类型以硫化、硅化、绢云母化及碳酸盐化为主。尽管容矿岩石类型多样, 但成矿期黄铁矿普遍富集Au、As、Sb、Cu及Bi等成矿元素。LA-ICP-MS锆石U-Pb测年结果显示, 赋矿花岗闪长斑岩侵位年龄约为240 Ma, 并识别出约220 Ma的晚期岩浆活动信号。与区域典型金矿床(如早子沟、加甘滩超大型金矿)对比表明, 拉古河金矿具有中三叠世与侵入岩相关金矿化和晚三叠世浅成造山型金矿化的叠加成矿特征, 可能为三叠纪洋-陆俯冲向陆-陆碰撞转换过程中多期岩浆-热液活动的产物。综合控矿构造与有利岩性组合分析, 结合区域成矿规律, 认为沿北西向断裂带延伸方向及现有勘查区深部仍具良好找矿前景。 |
| 中文关键词:西秦岭造山带 拉古河金矿 金的赋存形式 矿化特征 成矿和找矿指示 |
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| Mineralization Geological Characteristics, Genesis, and Exploration Implications of the Laguhe Gold Deposit, West Qinling Orogen |
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| Abstract:The Laguhe gold deposit is a newly discovered large-scale disseminated gold deposit in the Xiahe–Hezuo district, in the central segment of the West Qinling Orogen. Studying its mineralization characteristics and genesis is of great significance for understanding regional gold mineralization and for guiding future mineral exploration. Based on a detailed description of the mineralization characteristics of the deposit, combined with petrographic and mineralographic observations, in-situ chemical composition analysis of pyrite, and zircon U-Pb dating of the host granodiorite porphyry, this study discusses the ore genesis of the deposit and its implications for regional prospecting. The results indicate that the Laguhe gold deposit comprises vein- and lens-shaped disseminated gold orebodies controlled by faults and interbedded fracture zones. Gold occurs mainly as invisible gold in arsenian pyrite and arsenopyrite, which are finely disseminated in granodiorite porphyry, sandstone, and silty slate. Minor particles of native gold are also observed. Wall-rock alteration is dominated by sulfidation, silicification, sericitization, and carbonatization. Although the host rocks vary in lithology, ore-stage pyrite universally shows enrichment in Au, As, Sb, Cu, and Bi. Laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb dating yielded an emplacement age of approximately 240 Ma for the ore-hosting granodiorite porphyry, along with evidence of a later magmatic event at ca. 220 Ma. A comparative analysis with typical regional gold deposits (such as the Zaozigou and Jiagantan giant gold deposits) suggests that the Laguhe deposit exhibits characteristics of both Middle Triassic intrusion-related gold mineralization and Late Triassic epizonal orogenic gold mineralization. It was likely formed through multiple episodes of magmatic-hydrothermal activity during the Triassic transition from oceanic-continental subduction to continental-continental collision. Integrated analysis of ore-controlling structures and favorable lithologies, together with regional metallogenic patterns, indicates that the extension of the NW-trending fault zone and the deeper sections of existing exploration areas remain highly prospective for further discovery. |
| keywords:west Qinling Orogen Laguhe gold deposit gold occurrences forms mineralization characteristics ore genesis and exploration implications |
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