格陵兰东部Jameson Land盆地铜多金属矿床地球化学特征及成因探讨

发布时间：2018-03-08 08:11

  本文选题：铜多金属矿床　切入点：矿床地球化学特征　出处：《东华理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：格陵兰是世界上重要的巨型多金属成矿带之一,Jameson Land盆地属格陵兰东部成矿带。Jameson Land盆地位于格陵兰岛东部的火山裂谷边缘,是形成于加里东期造山运动的拉张断陷盆地,盆地基底为前寒武纪变质岩,盆地盖层形成始于中泥盆世,盆地内各种沉积物堆积厚度达到17公里。经研究发现区内Cu、Pb、Zn等金属地表矿化特征明显、矿化强度大、分布范围广、厚度大,矿体形态呈层状、似层状,且矿化主要受地层层位控制,具备形成大型甚至超大型沉积岩容矿层状铜矿床的条件,找矿前景巨大。但目前对该区科学研究几乎为空白,所以有必要对该区进一步开展关于矿床的成矿地质和系统的地球化学研究工作,从而分析成矿物质来源、成矿流体演化特征等矿床成因机制等科学问题。本文通过对Jameson Land盆地所在铜多金属矿床区域的成矿地质背景分析,综合野外地质调查工作和流体包裹体、C-O同位素、S同位素等地球化学的分析研究,取得了研究区的初步认识有:1)通过对研究区矿石矿物显微研究,发现金属硫化物赋存形式多样,既表现有同生沉积的特征,又有后期改造的特点,认为研究区铜多金属矿床具有同生沉积-成岩-后期热液改造的特点。2)通过与矿石矿物共生的脉石矿物(石英和重晶石)流体包裹体测温得出均一温度范围113~387℃,平均值为185℃,温度集中在120~220℃之间,显示为中低温成矿流体;盐度范围在0.4ωt%~13.4ωt%之间,平均为7.9ωt%,峰值出现在6.0ωt%~13.0ωt%之间,显示流体为中低盐度成矿流体;流体密度范围在0.73~0.98g/cm3之间,平均值0.94g/cm3;均一温度-盐度典型热液流体类型图可以看出,成矿流体为大气降水和与海水的混合。3)矿区方解石δ13CVPDB为-4.7‰~0.5‰,平均值-2.5‰,δ18OVPDB变化范围为-26.0~-14.0‰,平均值-15.2‰,碳氧同位素图解表明碳来源于海相碳酸盐岩(即围岩)的溶解,也说明流体与围岩发生了水岩反应;金属硫化物硫δ34S在-11.0~3.8‰之间,平均值-3.9‰;重晶石δ34S在13.4~15.2‰之间,平均值14.0‰。4)硫源来自三叠纪的蒸发岩和有机质的还原作用,成矿金属物质来源于Ravnefjeld组页岩、下伏中泥盆世磨拉石建造和围岩。综合以上研究得出Jameson Land盆地的铜多金属矿床为典型的沉积-改造型矿床。
[Abstract]:Greenland is one of the most important giant polymetallic metallogenic belts in the world. The Jameson Land basin belongs to the eastern Greenland metallogenic belt. The Jameson Land basin is located on the edge of the volcanic rift in eastern Greenland and is formed in the Caledonian orogenic extensional fault basin. The basement of the basin is Precambrian metamorphic rock, the caprock formation of the basin began in the middle Devonian, and the thickness of various sediments in the basin reached 17 kilometers. The orebody is stratiform and layered in thickness, and mineralization is mainly controlled by stratigraphic strata. It has the conditions to form large or even super-large sedimentary rock ore bearing layered copper deposits, and the prospecting prospect is great. However, there is almost no scientific research in this area at present. Therefore, it is necessary to further study the ore-forming geology and systematic geochemistry of the deposits in this area, so as to analyze the source of the ore-forming materials. In this paper, the metallogenic geological background of the copper polymetallic deposit in the Jameson Land basin is analyzed by means of the metallogenic mechanism of ore deposits, such as the evolution characteristics of ore-forming fluids, and so on. Based on the field geological survey and the analysis of the geochemistry of fluid inclusions, such as C-O isotopes and S isotopes, a preliminary understanding of the study area has been obtained. Through the microscopic study of ore minerals in the study area, it is found that there are various forms of metallic sulphides. It not only shows the characteristics of syngenic deposition, but also has the characteristics of late transformation. It is considered that the copper polymetallic deposits in the study area have the characteristics of syngenic deposition-diagenesis and late hydrothermal transformation. 2) the homogeneous temperature range of 113 ~ 387 鈩，

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