Multi-stage Mineralization in the Giant Erdaokan Ag-Pb-Zn Deposit,Northeastern China:Evidence from Magnetite EPMA and LA-ICPMS Geochemistry  

作　　者：FU Anzong LI Chenglu YANG Wenpeng Masroor ALAM DENG Changzhou YANG Yuanjiang ZHENG Bo ZHAO Ruijun YUAN Maowen 

机构地区：[1]Natural Resources Survey Institute of Heilongjiang Province,Harbin 150036,China [2]School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China [3]Department of Earth Sciences,Karakoram International University,Gilgit 15100,Pakistan [4]State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China

出　　处：《Acta Geologica Sinica(English Edition)》2025年第2期532-552,共21页地质学报(英文版)

基　　金：financially supported by the Heilongjiang Provincial Key R&D Program Project(No.GA21A204);Heilongjiang Provincial Natural Science Foundation of China(No.LH2022D031);the Research Project of Heilongjiang Province Bureau of Geology and Mineral Resources(No.HKY202302).

摘　　要：Although previous researchers have attempted to decipher ore genesis and mineralization in the Erdaokan Ag-Pb-Zn deposit,some uncertainties regarding the mineralization process and evolution of both ore-forming fluids and magnetite types still need to be addressed.In this study,we obtained new EPMA,LA-ICP-MS,and in situ Fe isotope data from magnetite from the Erdaokan deposit,in order to better understand the mineralization mechanism and evolution of both magnetite and the ore-forming fluids.Our results identified seven types of magnetite at Erdaokan:disseminated magnetite(Mag1),coarse-grained magnetite(Mag2a),radial magnetite(Mag2b),fragmented fine-grained magnetite(Mag2c),vermicular gel magnetite(Mag3a1 and Mag3a2),colloidal magnetite(Mag3b)and dark gray magnetite(Mag4).All of the magnetite types were hydrothermal in origin and generally low in Ti(<400 ppm)and Ni(<800 ppm),while being enriched in light Fe isotopes(δ^(56)Fe ranging from−1.54‰to−0.06‰).However,they exhibit different geochemical signatures and are thus classified into high-manganese magnetite(Mag1,MnO>5 wt%),low-silicon magnetite(Mag2a-c,SiO_(2)<1 wt%),high-silicon magnetite(Mag3a-b,SiO_(2)from 1 to 7 wt%)and high-silicon-manganese magnetite(Mag4,SiO_(2)>1 wt%,MnO>0.2 wt%),each being formed within distinct hydrothermal environments.Based on mineralogy,elemental geochemistry,Fe isotopes,temperature trends,TMg-mag and(Ti+V)vs.(Al+Mn)diagrams,we propose that the Erdaokan Ag-Pb-Zn deposit underwent multi-stage mineralization,which can be broken down into four stages and nine sub-stages.Mag1,Mag2a-c,Mag3a-b and Mag4 were formed during the first sub-stage of each of the four stages,respectively.Additionally,fluid mixing,cooling and depressurization boiling were identified as the main mechanisms for mineral precipitation.The enrichment of Ag was significantly enhanced by the superposition of multi-stage ore-forming hydrothermal fluids in the Erdaokan Ag-Pb-Zn deposit.

关 键 词：multi-stage mineralization magnetite geochemistry in situ Fe isotope Erdaokan Ag-Pb-Zn deposit 

分 类 号：P618.41[天文地球—矿床学]