| 上黑龙江盆地砂宝斯金矿黄铁矿地球化学特征及其成矿意义 |
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| 关键词:pyrite in situ trace elements S-Pb isotopes Shabaosi gold deposit Upper Heilongjiang Basin |
| 基金项目:中国地质调查局项目(编号: DD20220985);国家重点研发计划项目(编号: 2017YFC0601303) |
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| Geochemical Characteristics of Pyrite from the Shabaosi Gold Deposit in the Upper Heilongjiang Basin and Its Mineralization Significance |
| The Shabaosi gold deposit is the only large-scale rock gold deposit in the Upper Heilongjiang Basin,but the source of ore-forming metrials and ore genesis of this deposit remain controversial. Therefore, based on detailed ore mineralogy and pyrite microstructure analysis, LA-ICP-MS trace elements and S, Pb isotopic analysis were carried out on different generations of pyrite. The results showed that pyrite in Shabaosi gold deposit can be divided into three generations (i.e., PyI, PyII and PyIII) from early mineralization to the main mineralization stage, and different phases of pyrite have obviously different trace element compositions. PyII is the main metallogenic stage of the deposit, in which elements such as Au, Ag, Cu, Pb, Zn, Bi, Co, Ni, As, Mn, Sb, Sn, and Ga had relatively high contents. Co, Ni, and As in the three generations of pyrite occur as homo-isomorphs form in the overall pyrite. Cu, Pb, Zn, Sb, Bi elements occur in Pyrite in the form of metallic Sulfide mineral inclusions. Au occurs as Au+, silver-gold, copper-gold mineral particles and submicron-sized Au particles in pyrite. As replaces S to form Au(HAs)-, which plays an important role in the migration and precipitation of Au. The majority of Co/Ni ratio is less than 1, most of which fall within the category of sedimentary area. While some points of PyI and PyⅢ type Pyrite Co/Ni fall into hydrothermal area and volcanic area. These indicate that Pyrites from the deposit is not a single source. Combining the S and Pb isotopic characteristics and trace elements of pyrite, the source of ore-forming materials of the deposit was derived from deep magma source with a mixture of upper crust and mantle characteristics and the surrounding strata Ershierzhan Formation. Combined with the regional metallogenic background, it is believed that the initial ore-forming fluids formed by Early Cretaceous magmatism formed PyI type Pyrite. And the Early Cretaceous magmatism was triggered by the continental crust delamination after the closure of the Mongolia Okhotsk Ocean. The content of Cu, Pb, Zn, Ag, Au and Bi from PyI type Pyrite is relatively low, and the content of Co and Ni is relatively high. Due to the addition of meteoric water, the ore-forming fluids extracted the ore-forming material in the Ershierzhan Formation, rich in As, Cu, Pb, Bi, Au, Ag, forming the sedimentary PyII type Pyrite. PyⅢ type Pyrite of both sedimentary and hydrothermal origin was formed due to the reduction of meteoric water in the late stage of mineralization. Therefore, the Shabaosi gold deposit is considered to be a magmatic hydrothermal gold deposit. |
| WANG Yuanchao,TAN Wei,ZHAO Yuanyi,LIU Jinlong,HE Li,CHEN Hang,HUANG Junhai,GONG Xin.2024.Geochemical Characteristics of Pyrite from the Shabaosi Gold Deposit in the Upper Heilongjiang Basin and Its Mineralization Significance[J].Acta Geoscientica Sinica,45(3):320-336. |
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