| 西秦岭纳合尔金矿床成因——来自毒砂矿物化学及硫同位素特征的证据 |
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| 引用本文：韦利莉,唐菊兴,邹兵,李发桥,刘杰,熊妍,张琪,孟五一,王琦,黄深川,旦增宗追.2026.西秦岭纳合尔金矿床成因——来自毒砂矿物化学及硫同位素特征的证据[J].地球学报,47(5):1133-1149. |
| DOI：10.3975/cagsb.2026.061121 |
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| 基金项目:本文由深地国家科技重大专项课题(编号: 2025ZD1009600)、中国地质科学院矿产资源研究所基本科研业务费专项经费(编号: KK2513)、甘肃省地矿局院士专家工作站项目(编号: GSDKAEW2024)、甘肃省地勘基金项目“甘肃省夏河县纳合尔金矿普查”(编号: 202202-D02; 202401-D02)、中国地质调查局地质调查项目(编号: DD2026021101)联合资助。 |
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| 中文摘要:纳合尔金矿床是西秦岭夏河—合作矿集区近年勘查发现的中型金矿床, 对其成因尚不清楚。矿床发育大量的毒砂等载金矿物, 可分为独立自形毒砂(Apy1)和与黄铁矿共生毒砂(Apy2), 并细分出石英脉中(Apy1b、Apy2b)和岩石中(Apy1a、Apy2a)的毒砂, 这些特征是揭示矿床成因的关键。本文通过岩心编录与矿相学观察, 利用电子探针、激光剥蚀电感耦合等离子体质谱(LA-MC-ICP-MS)分析等方法, 系统开展毒砂的矿物化学、原位S同位素组成及地质温度计估算研究, 并采用主成分分析方法, 将纳合尔金矿床毒砂化学组成与全球不同类型金矿床进行对比。结果显示, Apy2b毒砂相对富集Ag、Au、Bi、Cr、Mn等元素, Au以晶格金或固溶体(Au+)形式存在于毒砂晶格内; 原位S同位素测试结果显示, 其δ34S值为–17.51‰ ~ –3.74‰, 硫主要来源于变质变形的围岩地层, 其形成温度为326.2~392.5 ℃, 为中高温、偏还原的变质流体环境, 属于与岩浆热液有关的造山型金矿。毒砂的Co、Ni、Ag、Bi、Au、Sb含量还可区分出造山型、卡林型金矿床。 |
| 中文关键词:毒砂 主微量元素 硫同位素 主成分分析 纳合尔金矿 西秦岭 |
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| Genesis of the Nahe’er Gold Deposit in the West Qinling Orogen: Constraints from Arsenopyrite Mineral Chemistry and Sulfur Isotope Signatures |
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| Abstract:The Nahe’er gold deposit is a medium-sized gold deposit recently discovered through exploration in the Xiahe–Hezuo ore cluster of the West Qinling region, whose genesis remains unclear. The deposit hosts an abundance of gold-bearing minerals such as arsenopyrite, which can be divided into independent euhedral arsenopyrite (Apy1) and arsenopyrite coexisting with pyrite (Apy2), further classified into arsenopyrite in quartz veins (Apy1b, Apy2b) and arsenopyrite in host rocks (Apy1a, Apy2a). These characteristics are key to unraveling the deposit's genesis. This study systematically investigates the mineral chemistry, in-situ sulfur isotope composition, and geothermometry of arsenopyrite through core logging, ore microscopy, electron probe microanalysis (EPMA), and laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Additionally, principal component analysis (PCA) was employed to compare the chemical composition of arsenopyrite from the Nahe’er gold deposit with that of arsenopyrite from various global gold deposit types.The results show that Apy2b arsenopyrite is relatively enriched in Ag, Au, Bi, Cr, Mn, and other elements, with Au existing in the arsenopyrite lattice as lattice-bound gold or solid solution (Au+). In-situ sulfur isotope analysis yielded δ3?S values ranging from –17.51‰ to –3.74‰, indicating that the sulfur was primarily derived from metamorphically deformed wall rocks. The estimated formation temperature (326.2~392.5 °C), suggesting a medium- to high-temperature, relatively reduced metamorphic fluid environment. The deposit is classified as an orogenic gold deposit associated with magmatic-hydrothermal activity. Furthermore, the concentrations of Co, Ni, Ag, Bi, Au, and Sb in arsenopyrite can effectively distinguish between orogenic and Carlin-type gold deposits. |
| keywords:arsenopyrite major and trace elements sulfur isotopes principal component analysis Nahe’er gold deposit West Qinling |
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