| 刘祥云,严庆文,胡体才,黄保胜,刘红伟,田罡豪,李吉富,任周洪,余泽章.云南会泽铅锌矿床上震旦统灯影组中新发现矿体成因：来自C-O-Sr同位素的制约[J].矿产勘查,2024,15(6):956-968 |
| 云南会泽铅锌矿床上震旦统灯影组中新发现矿体成因：来自C-O-Sr同位素的制约 |
| Origin of the newly discovered ore bodies in the Upper Sinian Dengying Formation of the Huize Pb-Zn deposit in Yunnan： Constraints from C-O-Sr isotopes |
| 投稿时间：2023-11-08 修订日期：2024-01-18 |
| DOI：10.20008/j.kckc.202406005 |
| 中文关键词: 铅锌矿床 震旦系 石炭系 灯影组 云南会泽 |
| 英文关键词: Pb-Zn deposits Sinian Carboniferous Dengying Group Huize,Yunnan |
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| 中文摘要: |
| 云南会泽铅锌矿床是中国川滇黔成矿带内的超大型铅锌矿床，前期发现的矿体主要集中在下石炭统摆佐组中，近年来在上震旦统灯影组中发现了新的矿体，但对该矿体的成因认识仍不清楚。本文针对会泽矿床上震旦统和下石炭统不同层位矿体，开展了近矿白云岩和热液方解石C-O同位素和矿石硫化物Sr同位素分析。上震旦统灯影组矿体中热液方解石（δ13CPDB为-10.6‰~-2.01‰、δ18OSMOW为17.91‰~22.44‰）、近矿白云岩（δ13CPDB为-2.22‰~-0.03‰、δ18OSMOW为21.28‰~25.99‰）和下石炭统摆佐组矿体中热液方解石（δ13CPDB为-3.99‰~-3.34‰、δ18OSMOW为19.15‰~20.18‰）、近矿白云岩（δ13CPDB为-2.67‰、δ18OSMOW为20.44‰）的C-O同位素特征，显示近矿白云岩与海相碳酸盐的C-O同位素组成基本一致，热液方解石可能是深源成矿流体和围岩之间发生C-O同位素交换作用的结果。前人研究指出会泽矿床上震旦统灯影组矿化和下石炭统摆佐组铅锌矿体成矿事件均为印支晚期强烈挤压造山运动产物，结合上震旦统灯影组矿体中硫化物（闪锌矿、黄铁矿）初始Sr同位素（（87Sr/86Sr）i=0.7148~0.7231，均值0.7192）与下石炭统摆佐组矿体中硫化物（闪锌矿、黄铁矿）初始Sr同位素（（87Sr/86Sr）i=0.7119~0.7218，均值0.7159）一致，接近成矿时期大陆地壳87Sr/86Sr平均值（0.719），说明形成上震旦统和下石炭统中矿体的成矿流体均具有地壳来源特征。成矿流体在不同的层位成矿，出现了“多层分布，集中产出”的特征，指示会泽矿床在上震旦统灯影组亦具有类似下石炭统摆佐组的找矿潜力。 |
| 英文摘要: |
| The Huize Pb-Zn deposit in Yunnan is a super large Pb-Zn deposit located within the Sichuan-Yunnan-Guizhou metallogenic belt of China. The ore bodies discovered previously were mainly concentrated in the Lower Carboniferous Baizuo Formation. In recent years， new ore bodies have been discovered in the Upper Sinian Dengying Formation， but the genesis of these ore bodies remains unclear. This article conducted C-O-Sr isotope analysis on near-ore dolomite and hydrothermal calcite in the the Upper Sinian Dengying Formation and Lower Carboniferous Baizuo Formation， and found that the Lower Carboniferous Baizuo Formation hydrothermal calcite （δ13CPDB=-10.6‰- -2.01‰； δ18OSMOW=17.91‰-22.44‰） and near-ore dolomite （δ13CPDB=-2.22‰- -0.03‰； δ18OSMOW=21.28‰-25.99‰）， is similar to the hydrothermal calcite in Lower Carboniferous Baizuo Formation ore bodies （δ13CPDB=-3.99‰- -3.34‰； δ18OSMOW=19.15‰-20.18‰） and near-ore dolomite （δ13CPDB=-2.67‰； δ18OSMOW=20.44‰）， which indicate the near-ore dolomite has a similar C-O isotope composition to marine carbonates and the hydrothermal calcite may be the result of C-O isotopic exchange between deep-source mineralizing fluids and wall rocks. Previous studies have pointed out that the mineralization events of the Upper Sinian Dengying Formation and the Lower Carboniferous Baizuo Formation lead-zinc deposits in the Huize deposit are both products of strong compression orogeny in the late Indosinian period. Combined with the initial Sr isotopes of sphalerite and pyrite （（87Sr/86Sr）i = 0.7148-0.7231， mean=0.7192） in the ore bodies from Upper Sinian Dengying Formation strata are consistent with those in the Lower Carboniferous Baizuo Formation ore bodies of the Carboniferous system （（87Sr/86Sr）i=0.7119-0.7218， mean=0.7159）， mainly characterized by crustal source characteristics. This indicates that the ore bodies in the Sinian and Carboniferous systems have similar crustal source characteristics. The ore-forming fluids mineralize at different layers， exhibiting a "multi-layer distribution and concentrated output" feature. This understanding indicates that the Sinian strata in Huize area also have prospecting potential similar to the Carboniferous strata. |
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