三山岛金矿床断裂带渗透性结构及其控矿模式

发布时间：2018-06-10 20:10

本文选题：渗透性结构 + 断裂带结构构造　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：三山岛金矿床是三山岛-仓上断裂带上的超大型破碎蚀变岩型金矿床,不仅是我国重要的黄金工业基地,也是是我国最具找矿远景和成矿潜力的区域之一。该矿床严格受断裂构造控制,对矿床的断裂带与矿体关系、控矿机理等问题仍存在分歧。本文结合在翔实的野外地质调查和室内观察分析基础之上,重点对该金矿区断裂带构造分带、变形特征及蚀变-矿化分带,断裂带渗透性结构及渗透率测试方法进行了详细研究,并运用回归分析方法初步探讨其断裂带构造控矿模式,对该金矿床找矿预测提供相关的理论依据。主要取得以下认识:(1)三山岛金矿床断裂带具有明显的构造分带性,自主断裂面向外沿下盘依次发育断层泥、构造透镜体、密集节理带、构造薄弱带。断层泥分为三层(黑色、灰色、灰白色),有明显的多期次变形特征;由主断裂向外显微构造变形由韧-脆性过渡到脆性,结合EBSD显微组构分析,构造透镜体、密集节理带的变形温度约为300~400°C,压剪性环境;构造薄弱带的变形温度200~300°C,张剪性环境,变形温度逐渐降低。(2)三山岛金矿床断裂带具有水平分带为主的蚀变-矿化特征。构造透镜体带内为黄铁绢英岩化蚀变和硫化作用,矿体赋存于黄铁绢英岩内,密集节理带内为绢英岩化、硅化,节理发育密集,矿体多以浸染状赋存于绢英岩内,次级断裂内赋存石英-硫化物脉和方解石脉;构造薄弱带主要发育钾化蚀变,含少量细脉型矿体。其蚀变-矿化分带与断裂带构造分带具有对应关系。(3)根据断裂带渗透性结构特征的观察描述,将其划分为三类:主干断裂、末端断裂、孤立断裂,并且随着成矿演化的进行,应力不断改变,这三类渗透性结构亦可相互转化,从而在成矿期内,为流体的运移和成矿提供足够的通道和容矿空间。对成矿早阶段、成矿主阶段不同中段及蚀变分带内围岩渗透率的测定分析,同一中段内成矿早阶段围岩渗透率明显低于成矿主阶段的围岩;沿主断面向外沿下盘渗透率依次由低变高再变低(0.02→0.24→0.06);不同深度的中段近地表处围岩的渗透率较高,且矿体规模较大。(4)依据断裂带渗透性构造与蚀变-矿化的时空结构关系特征,运用回归分析说明渗透率对矿体厚度有影响,初步探讨三山岛断裂带构造控矿模式。
[Abstract]:Sanshandao gold deposit is a super large broken altered rock type gold deposit in the Sanshando-Cangshang fault zone. It is not only an important gold industrial base in China, but also one of the most promising and metallogenic regions in China. The ore deposit is strictly controlled by the fault structure, and there are still differences on the relationship between the fault zone and the orebody and the ore-controlling mechanism of the deposit. On the basis of detailed field geological survey and laboratory observation and analysis, this paper focuses on the structural zoning, deformation characteristics and alteration mineralization zoning of the fault zone in this gold ore area. The permeability structure and permeability testing method of the fault zone are studied in detail, and the structural ore-controlling model of the fault zone is preliminarily discussed by means of regression analysis, which provides the relevant theoretical basis for the prospecting and prediction of the gold deposit. The main conclusions are as follows: (1) the fault zone of Sanshandao gold deposit has obvious structural zonation, and the fault gouge, structural lens, dense joint zone and structural weak zone are developed successively in order of independent fault facing the outer footwall. The fault gouge is divided into three layers (black, grayish white, with obvious multi-stage deformation characteristics, from main fault to outer microstructural deformation from ductile-brittle to brittle, combined with EBSD microscopic fabric analysis, structural lens, The deformation temperature of the dense joint zone is about 300 ~ 400 掳C, and that of the tectonic weak zone is 200 ~ 300 掳C, and the deformation temperature is decreasing gradually. 2) the fault zone of Sanshandao gold deposit is characterized by alteration and mineralization, which is dominated by horizontal zonation. In the structural lens zone, the alteration and vulcanization of yellow sericite occurs in the orebody, and in the dense joint zone there is sericolith, silicification, dense development of joints, and the orebodies occur in the silky rocks in the form of leaching. Quartz sulphide vein and calcite vein exist in the secondary fault and the structural weak zone is mainly composed of potash alteration with a small number of veinlike orebodies. According to the observation and description of the permeability structure of the fault zone, it can be divided into three types: main fault, terminal fault, isolated fault, and with the development of metallogenic evolution. With the change of stress, these three types of permeable structures can also be transformed into each other, thus providing sufficient channels and ore-bearing space for fluid migration and mineralization during the metallogenic period. According to the measurement and analysis of the permeability of the surrounding rock in the different middle and altered zones in the early stage of mineralization, the permeability of the surrounding rock in the early stage of mineralization in the same middle section is obviously lower than that in the main stage of mineralization. Along the main section to the outer side, the permeability changes from low to high and then to low 0.02 ~ 0.24 ~ 0.06m, and the permeability of surrounding rock near the surface is higher at different depths. According to the relationship between permeability structure and alteration mineralization in fault zone, the regression analysis shows that permeability has influence on the thickness of orebody, and the structural ore-controlling model of Sanshandao fault zone is discussed preliminarily.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.51

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