| 黔西北普宜地区富关键金属元素硫铁矿地质、地球化学和S同位素特征及其对成因的约束 |
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| 引用本文： | 张七道,肖长源,李致伟,李锁明,孙建勋,田瑜峰,李金旺,李辰.黔西北普宜地区富关键金属元素硫铁矿地质、地球化学和S同位素特征及其对成因的约束[J].地质科技通报,2022,41(4):149-164. |
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| 作者姓名： | 张七道 肖长源 李致伟 李锁明 孙建勋 田瑜峰 李金旺 李辰 |
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| 作者单位： | 1.中国地质调查局昆明自然资源综合调查中心, 昆明 650111 |
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| 基金项目： | 中国地质调查局项目DD20191012 |
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| 摘 要： | 探讨黔西北普宜地区富关键金属元素硫铁矿的同位素地球化学特征、元素地球化学特征及成因, 可以为硫铁矿资源开发、伴生有益元素综合利用与评价及理解富关键金属元素硫铁矿聚集机制提供更为丰富的信息。在全面收集已有地质、矿产资料的基础上, 结合野外实地调查, 应用元素地球化学及硫同位素分析等方法, 对该区硫铁矿地球化学特征及成因做了较为深入研究, 并初步建立成矿模式。结果表明: 富关键金属元素硫铁矿主要赋存于中二叠统龙潭组(P2l)底部的晶屑凝灰岩中, 矿体形态简单, 呈层状分布, 硫铁矿中共(伴)生的稀土, Li, Nb, Zr, Ga等有益元素均可综合利用。w(ΣREE)平均为431.24×10-6, 最大值为1 634.57×10-6, 一般在180×10-6~1 630×10-6之间; w(Ga)平均为32.51×10-6, 一般为25×10-6~120×10-6, 最大为120.00×10-6; w(Nd)平均为103.29×10-6, 一般为40×10-6~380×10-6, 最大为380.00×10-6; w(Li)最大值为1 366.00×10-6; w(Al2O3)最大值为42.17%。硫铁矿稀土元素配分模式表现为轻稀土元素富集、重稀土元素相对亏损的右倾型。矿石中成矿元素Ga, Li, Zr, Ti, Se, Cd, Nb, V, Hg等元素相对富集, Ba, Sr, Zn, Te等元素相对贫化。硫铁矿石中黄铁矿硫同位素δ34S变化范围主要在-33.90‰~-18.60‰之间, 平均值-16.04‰, 为轻硫富集型, 富关键金属元素硫铁矿的硫源受生物细菌还原作用影响较大。硫铁矿主要是在沉积阶段通过微生物铁还原、微生物硫酸盐还原和化学铁还原驱动下形成的。初步认为赋存于硫铁矿中的稀土主要以类质同象替代形式赋存于黏土矿物中, 形成过程可分为风化搬运阶段、沉积成矿阶段和成岩后生作用阶段。
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| 关 键 词： | 硫铁矿 硫同位素 关键金属 成因 普宜地区 黔西北 |
| 收稿时间： | 2021-04-26 |
Geological,geochemical and sulfur isotopic characteristics of critical metal-enriched pyritic ore in the Puyi area,northwest Guizhou Province: Constraints on the genesis of the deposit |
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| Institution: | 1.Kunming Comprehensive Natural Resources Survey Center, China Geological Survey, Kunming 650111, China2.China University of Geosciences(Wuhan), Wuhan 430074, China |
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| Abstract: | The study of the isotopic and elemental geochemical characteristics and genesis of critical metal-enriched pyritic ore in the Puyi area of Northwest Guizhou provides more abundant information for the exploitation of pyritic ore resources, comprehensive utilization and evaluation of associated beneficial elements, and understanding the mechanism of critical metal-enriched pyritic ore. Based on the comprehensive collection of existing geological and mineral data, combined with field investigation, the geochemical characteristics and genesis of pyrite in this area are studied by using element geochemistry and sulfur isotope analysis, and the metallogenic model is preliminarily established. The study shows that the critical metal-enriched pyritic ore mainly occurs in the crystalline tuff at the bottom of the Longtan Formation of the middle Permian(P2l), and the ore body is simple in shape and distributed in layers. The beneficial elements, such as REEs, Li, Nb, Zr, Li, Nb, Zr, Ga, can be comprehensively utilized. The results show that ΣREE usually ranges from 180×10-6 to 1 630×10-6, with an average of 431.24×10-6 and up to 1 634.57×10-6; Ga usually ranges from 25×10-6 to 120×10-6, with an average of 32.51×10-6 and up to 120.00×10-6; Nd generally ranges from 40×10-6 to 380×10-6, with an average of 103.29×10-6 and up to 380.00×10-6; and the maximum values of Li and Al2O3 are 1 366.00×10-6 and 42.17%. The REE distribution pattern of pyritic ore is characterized by enrichment in LREEs and relative depletion in HREEs. The ore-forming elements Ga, Li, Zr, Ti, Se, Cd, Nb, V and Hg are relatively enriched, while Ba, Sr, Zn and Te are relatively depleted. The δ34S of pyrite in pyritic ore mainly range from -33.90‰ to -18.60‰(on average of -16.04‰), which shows the characteristics of the enrichment of light sulfur. The sulfur source of critical metal-enriched pyritic ore was greatly affected by the reduction of biological bacteria. Pyritic ore is mainly formed in the sedimentary stage by microbial iron reduction, microbial sulfate reduction and chemical iron reduction. It is suggested that REEs in pyritic ore mainly occur in clay minerals in the form of similar isomorphic substitution, and the formation process can be divided into the weathering transportation stage, sedimentary mineralization stage and diagenetic epigenetic stage. |
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