冀东唐杖子金多金属矿床地质—地球化学特征与成矿作用研究

发布时间：2018-04-22 05:02

  本文选题：岩浆期后热液矿床 + 板块内部拉张环境　； 参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：唐杖子金多金属矿床位于冀东宽城县南东约17km处,大地构造位置处于华北克拉通北缘中段,燕山褶断带。本次工作主要目的是研究成岩—成矿相互关系、流体来源和成矿物质来源,探讨成矿作用机制。通过矿区的金属硫化物电子探针分析、岩浆岩锆石U-Pb年龄及Hf同位素组成、全岩地球化学分析、流体包裹体显微测温、流体包裹体的H-O同位素组成和金属硫化物的S及He-Ar同位素组成的研究,取得了以下认识:根据矿体地质特征、矿石矿物组合、脉体穿插关系,将整个矿床成矿过程划分成了2个成矿亚期,6个成矿阶段。辉钼矿成矿亚期分3个阶段:钾长石阶段、辉钼矿化阶段、黄铁矿—碳酸盐阶段。金多金属成矿亚期分3个阶段:黄铁矿—石英阶段、金多金属矿化阶段、石英—碳酸盐阶段。金主要赋存在烟灰色石英粗脉中,或与黄铁矿、黄铜矿、闪锌矿、方铅矿等金属硫化物伴生。金属硫化物电子探针分析结果表明,金主要赋存在金多金属硫化阶段的黄铁矿中。银主要与方铅矿、银黝铜矿伴生,且主要赋存在银黝铜矿中。采自370m平硐中段的花岗斑岩锆石U-Pb年龄分别为161.23±0.65Ma(A组)、173.0±5.5Ma(B组)。B组年龄代表成岩年龄,A组锆石可能是到成岩期后热液活动影响,丢失了放射性成因Pb,从而得到较小年龄。花岗斑岩锆石测年结果限定了唐杖子金矿的成矿时间下限为173.0±5.5Ma。结合前人对该区域的构造背景研究和花岗斑岩、辉绿岩的地球化学分析结果,认为成矿构造背景应为板块内部的局部拉张环境。不同成矿阶段流体包裹体的显微观察、测温结果表明,成矿流体属于中温、中低盐度的H2O-CO2-Na Cl体系。测得具有代表性的金多金属硫化物阶段的流体包裹体均一温度范围在143.7℃~320℃,峰值介于170℃~240℃,盐度为4.96%~11.7%,密度为0.96 g/cm3~0.81 g/cm3。H、O同位素组成表明,成矿流体主要来源于岩浆水,并有少量大气水的加入。金属硫化物的S、He-Ar同位素组成表明,矿物主要来源于地壳。
[Abstract]:The Tangchangzi gold polymetallic deposit is located at 17km in the south east of Kuancheng County in eastern Hebei Province. The tectonic position is in the middle section of the northern margin of North China Craton and the Yanshanian fold fault belt. The main purpose of this work is to study the relationship between diagenesis and metallogenesis, the source of fluid and ore-forming material, and the mechanism of mineralization. Through electron probe analysis of metallic sulfides, zircon U-Pb age and HF isotopic composition of magmatic rocks, whole rock geochemistry analysis, microthermometry of fluid inclusions, The H-O isotopic compositions of fluid inclusions and the S and He-Ar isotopic compositions of metallic sulphides have been studied. The metallogenic process of the deposit is divided into two metallogenic substages and six metallogenic stages. The sub-stage of molybdenum mineralization is divided into three stages: potassium feldspar stage, molybdenum mineralization stage and pyrite carbonate stage. The gold polymetallic metallogenic substage is divided into three stages: pyrite-quartz stage, gold polymetallic mineralization stage, quartz-carbonate stage. Gold mainly occurs in the hayotinite quartz veins, or with pyrite, chalcopyrite, sphalerite, galena and other metal sulfides. The results of electron probe analysis of metallic sulphide indicate that gold mainly occurs in pyrite during the sulfidation stage. Silver is mainly associated with galena, tetrahedrite and mainly occurs in silver tetrahedrite. The U-Pb age of granitic porphyry zircon collected from the middle part of 370m adit is 161.23 卤0.65Ma(A group (173.0 卤5.5Ma(B group). The age of group B represents the diagenetic age group A zircon may be affected by hydrothermal activity after diagenesis, and the radiogenic Pb is lost, thus the younger age can be obtained. The zircon dating results of granitic porphyry indicate that the lower limit of metallogenic time of Tangzhang gold deposit is 173.0 卤5.5 Ma. Based on the previous studies on the tectonic setting of the area and the geochemical analysis of granitic porphyry and diabase, it is concluded that the metallogenic tectonic setting should be a local extensional environment within the plate. The microscopical observation of fluid inclusions in different metallogenic stages shows that the ore-forming fluid belongs to H2O-CO2-Na Cl system with medium temperature and low salinity. The homogenization temperature range of fluid inclusions in the representative gold polymetallic sulphide stage is 143.7 鈩，

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