湖南宝山铜铅锌多金属矿床方解石REE和C-O同位素地球化学特征及其意义  

Geochemical Characteristics of REE and C-O Isotope of Calcites from the Baoshan Cu-Pb-Zn Polymetallic Deposit,Hunan Province,China and Their Significances

作　　者：孙黎鹏 吴鹏[1,2] 韩润生[1,2] 祝干 赵冻 SUN Lipeng;WU Peng;HAN Runsheng;ZHU Gan;ZHAO Dong(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China;Southwest Institute of Geological Survey,Geological Survey Center for Non-ferrous Metals Resources,Kunming Yunnan 650093,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]有色金属矿产地质调查中心西南地质调查所,云南昆明650093

出　　处：《矿物学报》2025年第1期98-110,共13页Acta Mineralogica Sinica

基　　金：国家重点研发计划项目(批准号:SQ2018YFC06017102);云南省矿产资源预测评价工程实验室项目(2010);云南省地质过程与矿产资源创新团队项目(2012)。

摘　　要：宝山铜铅锌多金属矿床位于东西向南岭构造-岩浆-成矿带与北东向钦杭成矿带叠合处,是湘南钨锡铜多金属矿集区的重要组成部分,其规模达到大型,为该区典型矿床。针对该矿床成矿流体来源及演化问题,本文选取矿床深部–110 m、–270 m中段不同产状的6类方解石为研究对象,开展REE元素和C-O同位素研究,取得主要认识:1)REE配分特征表明,与多金属矿化密切相关的Ⅰ类方解石的REE配分特征指示成矿物质主要来源于花岗闪长斑岩;Ⅱ类方解石的REE配分特征则指示成矿物质部分来自于围岩。2)Ⅰ类、Ⅱ类方解石的Eu异常指示成矿流体可能经历了由中-高温、氧化阶段向低温、还原阶段演化的过程。3)不同类型方解石C-O同位素值分散,δ13C_(V-PDB)值范围为–5.04‰~2.80‰,δ18O_(V-SMOW)值范围为7.17‰~29.11‰,这种差异指示C主要来源于海相碳酸盐岩的溶解作用和花岗岩;O来源于岩浆水和大气降水混合,指示成矿物质具多源性。综上所述,本研究认为该矿床成矿流体主要来源于深层岩浆热液和大气降水,沿区域深大断裂及围岩的断裂构造运移,淋滤矿区广泛分布的海相碳酸盐岩地层,萃取围岩中的成矿元素,从而富集成矿。本研究从REE和C-O同位素角度进一步揭示了该矿床成矿流体的来源与演化规律,为正确厘定矿床的成因提供了新的依据。The Baoshan Cu-Pb-Zn polymetallic deposit is located in the junction part of the EW-trending Nanling tectonic-magmatic-metallogenetic belt and the NE-trending Qin-Hang metallogenetic belt,and is an important part of the W-Sn-Cu polymetallic ore districts in the southern Hunan.It is a large scale typical Cu-Pb-Zn polymetallic deposit in this area.Aiming at the origin and evolution of ore-forming fluid of the deposit,six types of calcites with different occurrences collected at–110 m and–270 m levels in the depth of the deposit are selected as the research objects in this paper for carrying out the REE and C-O isotope geochemical research.The following understandings have been achieved.(1)The REE distribution characteristics of the Type I calcite,which is closely related to polymetallic mineralization,indicate that the ore-forming materials were mainly derived from granodiorite porphyry,while those of the Type II calcite indicate that the ore-forming materials were partly sourced from wallrocks.(2)Eu anomalies of Type I and Type II calcites indicate that the ore-forming fluid could have gone through the evolution process from the middle-high temperature and oxidation stage to the low temperature and reduction stage.(3)The C-O isotopic values of different types of calcites are scattered with δ13CV-PDB values varying from–5.04‰ to 2.80‰ andδ18OV-SMOW values varying from 7.17‰to 29.11‰,respectively,indicating that the C was mainly originated from the dissolved marine carbonate rocks and granite,and the O was originated from the mixing of magmatic water and meteoric water.These indicate that the ore-forming materials were sourced from multiple origins.In summary,this study suggests that the ore-forming fluid of this deposit was mainly originated from the deep magmatic hydrothermal fluid and meteoric water.The ore-forming fluid was then transported along the regional deep faults and through fractures in wallrocks,to have leached and extracted the ore-forming elements from the wallrocks of marine carbonat

关 键 词：稀土元素 C-O同位素 成矿流体 方解石 宝山铜铅锌多金属矿床 湖南 

分 类 号：P611[天文地球—矿床学] P578.61[天文地球—地质学]