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贵州丹寨排庭金汞矿床地质地球化学特征
Geological and geochemical characteristics of the Paiting gold—mercury deposit in Danzhai, Guizhou
【摘要】 贵州丹寨金汞矿位于三都—丹寨金—汞—锑多金属成矿带,目前很少进行系统的成矿作用研究。笔者等通过野外调查及系统采样,结合电子探针、同位素分析等手段,对丹寨排庭金汞矿床地质地球化学特征及成因进行了系统研究。电子探针分析表明,不同阶段黄铁矿形状不一,且其中各元素含量不同,毒砂为主要载金矿物;辰砂矿石的稀土配分曲线类似于地层岩石,说明汞矿的成矿物质主要来源于地层;辰砂和辉锑矿的δ34SV-CDT (或δ34SCDT)为20.63‰~23.53‰,说明二者当中硫主要来源于地层,其次为生物硫。有机碳同位素δ13CV-PDB为-29.78‰~-30.45‰,方解石的δ13CV-PDB为-0.56‰~-5.97‰,δ18OV-SMOW为15.23‰~20.14‰,结合稀土元素配分型式,表明丹寨排庭金汞矿的成矿流体具有多期次、多来源性,其主要来源为岩浆热液,并结合了大气降水,有机质和生物的还原作用参与了成矿流体的演化,成矿流体中碳可能来源于地幔或岩浆岩或者不同端元流体的混合体,有机质提供了重要的碳源,氧主要来源于围岩。总之,排庭金汞矿床中金、锑、汞为不同期次,金为早期、接着是锑、汞为晚期,金主要来源于岩浆,金矿的形成主要为热液活动所致,而汞主要来源于地层,碳酸盐岩的溶解及沉积有机物的脱羟基作用在汞矿的形成过程中起重要作用。
【Abstract】 Objectives: The Danzhai gold—mercury deposit is located in the Sandu—Danzhai gold—mercury—antimony polymetallic metallogenic belt. The studies on gold deposits of Guizhou focus on the Southwest in Guizhou.However,there is no systematic study on Danzhai gold deposit so far. Geological,geochemical characteristics and genesis of the paiting gold—mercury deposit in Danzhai are studied in this paper.Methods: Field investigation and systematic sampling were carried out in this paper. Thin section from six samples for electron probe analysis of sulfides. Cinnabar from three samples of mercury ore for sulfur isotope analysis. Calcite from eight samples for carbon and oxygen isotopes analysis. Organic carbon from four limestone samples for carbon isotopes analysis.Results: Electron probe analysis shows that: Pyrite has different shapes in different stages and the content of each element is different. Au content in cinnabar is lower than the detection limit,and arsenopyrite is the main gold-bearing mineral.δ34SV-CDT( δ34SCDT) of cinnabar and stibnite varies from 20.63‰ to 23.53‰,δ13CV-PDB of organic carbon varies from-29. 78‰ to-30. 45‰,δ13CV-PDB of calcite varies from-0. 56‰ to-5. 97‰,δ18OV-SMOW varies from 15. 23‰ to 20. 14‰.The results show that: The sulfur of cinnabar and stibnite is mainly strata sulfur and biogenic sulfur; the oxygen of calcite comes from the surrounding rock; the carbon of metallogenetic fluids from multiple sources and organic carbon is one of the necessary sources.Conclusions: Pyrite is divided into diagenetic period pyrite and hydrothermal period pyrite. Hydrothermal period pyrite includes early metallogenetic stage pyrite( PyⅠ),main metallogenetic stage pyrite( PyⅡ) and late metallogenetic stage pyrite( Py Ⅲ) .Arsenopyrite is the main gold-bearing mineral. The sulfur of cinnabar and stibnite is mainly strata sulfur and biogenic sulfur. The metallogenetic fluids is mainly magmatic hydrothermal,which combined with some meteoric precipitation. The carbon in metallogenetic fluids may comes from a mixture of different end-member fluids,and the oxygen comes from surrounding rocks. Gold,antimony and mercury the Paiting gold—mercury deposit of are formed successively and belong to different metallogenic stages. Gold element is mainly derived from hypomagma,and the gold mineralization is related to magma. However,mercury is mainly derived from the strata,and the mercury mineralization is related to the the dissolution of carbonate rocks and the dehydroxylation of deposited organic matter. The sulfur of the mercury ore and antimony ore is mainly strata sulfur and biogenic sulfur.
【Key words】 geochemistry; genesis of deposit; gold deposit; mercury deposit; Danzhai,Guizhou;
- 【文献出处】 地质论评 ,Geological Review , 编辑部邮箱 ,2019年05期
- 【分类号】P618.51;P618.68
- 【被引频次】5
- 【下载频次】139