投稿时间：2024-11-25
修订日期：2025-03-10
网络发布日期：2025-04-25
中文摘要:淋湘金矿床是南秦岭镇安-旬阳盆地南缘一处典型的微细浸染型金矿床。关于其成矿物质和成矿流体的来源，学界存在不同观点，且对成矿机制的认识尚不充分。本研究选取Ⅱ-Ⅲ主成矿阶段的石英和黄铁矿，分别进行了C-H-O同位素和Fe同位素分析，并采集了仁河口-双河镇断裂两侧志留系样品进行裂变径迹分析。研究结果表明，淋湘金矿床主成矿期δ13CV-PDB值为-10.59‰~-9.22‰，δ18OV-SMOW值为14.06‰~15.57‰，δD水-SMOW值为-82.10‰~-68.30‰，δ18O水值为4.52‰~8.97‰，表明成矿流体在运移中沿构造萃取地层成矿物质，并在成矿后期有深部岩浆的加入。δ56Fe值为-0.87~0.23，δ57Fe值为-0.43~0.18，指示成矿早期阶段成矿物质以壳源物质为主，随后幔源物质加入成矿作用。裂变径迹结果显示磊石沟地区120~0 Ma以来经历3个阶段，南沙沟地区120~0 Ma以来经历4个阶段，与镇旬盆地金成矿关系密切的太平洋板块向欧亚板块俯冲作用持续至90 Ma左右，45 Ma左右印度板块与欧亚板块碰撞的远场响应到达仁河口-双河镇断裂。镇旬盆地总体剥蚀厚度为(4.98±0.33)km，矿体被剥蚀程度较弱，深部具备良好的金成矿条件和巨大的找矿潜力。结合前人对南秦岭构造演化的认识，笔者认为在三叠纪时期陆内造山演化阶段形成大量含Au变质流体，在陆内造山运动晚期，盆地基底演化为伸展环境或碰撞后挤压-伸展过渡环境，幔源物质和流体随岩浆在减压条件下沿深大断裂上涌到地壳浅部，为金矿体的形成提供了热源、挥发分和少量成矿物质。
Abstract:The Linxiang gold deposit, located on the southern margin of the Zhen'an-Xunyang Basin in the South Qinling Mountains, Shaanxi Province, is a typical fine disseminated gold deposit. There are divergent views regarding the sources of ore-forming materials and fluids, and the understanding of the metallogenic mechanism remains insufficient. This study focuses on quartz and pyrite from the main mineralization stages (Ⅱ-Ⅲ), C-H-O isotope and Fe isotope analyses are conducted, respectively. Additionally, apatite fission track analysis was performed on Silurian strata from both sides of the Renhekou-Shuanghezhen fault. The results reveal that during the main mineralization period, the δ13CV-PDB values of the Linxiang gold deposit range from -10.59‰ to -9.22‰, δ18OV-SMOW values from 14.06‰ to 15.57‰, δ18OV-SMOW values from -82.10‰ to -68.30‰, and δ18Owater values from 4.52‰ to 8.97‰, indicating that the ore-forming fluids extracted materials from the strata along structural pathways during migration, with deep magmatic contributions in the late mineralization stage. The δ56Fe values range from -0.87‰ to 0.23‰, and δ57Fe values from -0.43‰ to 0.18‰, suggesting that the ore-forming materials were primarily crust-derived in the early stage, followed by mantle-derived contributions. Fission track analysis shows that the Leishigou area experienced three stages from 120 Ma to the present, while the Nanshagou area underwent four stages. The subduction of the Pacific Plate beneath the Eurasian Plate, closely related to gold mineralization in the Xunyang Basin, persisted until approximately 90 Ma. The far-field effects of the collision between the Indian Plate and the Eurasian Plate reached the Renhekou-Shuanghezhen fault around 45 Ma. The total erosion thickness is (4.98±0.33) km, with minimal erosion of the ore bodies, indicating favorable deep gold mineralization conditions and significant exploration potential. Integrating previous insights into the tectonic evolution of the South Qinling Mountains, this study proposes that abundant Au-bearing metamorphic fluids formed during the Triassic intracontinental orogenic evolution. In the late stage of intracontinental orogeny, the basin basement evolved into an extensional or post-collisional transitional environment, where mantle-derived materials and fluids ascended along deep faults under decompression, providing heat, volatiles, and minor ore-forming materials for the formation of gold deposits.
keywords:C-H-O isotope Fe isotope fission track metallogenic mechanism Linxiang gold deposit Zhenan-Xunyang Basin
文章编号：
中图分类号：
文献标志码：
基金项目:本文得到中国地质调查局地质调查项目(编号：DD20230206403、DD20251173、DD20230060)和新一轮找矿突破战略行动科技支撑项目（编号：ZKKJ202409）联合资助
引用文本：
薛仲凯,范堡程,李航,高永宝,魏立勇,马承.2025.镇旬盆地南缘淋湘金矿床流体来源及其成因探讨：C-H-O-Fe同位素、磷灰石裂变径迹的证据[J].矿床地质,44(2):413~431XUE ZhongKai,FAN BaoCheng,LI Hang,GAO YongBao,WEI LiYong,MA Cheng.2025.Discussion on fluid source and genesis of Linxiang gold deposit in southern margin of Zhenxun Basin: Evidence from C-H-O-Fe isotope and apatite fission track[J].Mineral Deposits44(2):413~431
图/表
