云南元阳大坪金矿床构造变形及其控矿特征研究

发布时间：2018-04-04 09:18

  本文选题：大坪金矿床　切入点：控矿构造特征　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：大坪金矿床被视为哀牢山造山带南段最典型的金矿床,矿体严格受成矿断裂构造控制。此区域构造活动频繁而强烈,具多期性、长期性和继承性的特点。构造不仅仅是控制着区内的地层分布、岩体侵位,更重要的是对矿体的分布有着严格制约,使其成为控矿的主导因素。该矿床的成矿主要受自东向西的NNW向小寨——金平断裂、NNW向小新街断裂和NW向三家河断裂的联合控制。以小新街断裂为界限,以东的矿脉分为东矿化带,研究主体为NW向V1-2-3矿脉;以西的矿脉分为西矿化带,研究主体为NNW向V9-8-14矿脉。为研究矿脉的构造运动学特征、控矿规律和变质变形作用,本文主要对矿脉矿体形态、矿脉的产状、构造透镜体和断层角砾岩的形态和空间分布、阶步和擦痕进行了详细的观察和研究,对韧性剪切带中的石英进行了EBSD组构分析,取得了如下成果和认识:(1)对两条矿脉的几何学研究均表明,两条矿脉在平面上呈串珠状、豆荚状分布,剖面上呈雁列状和等距状分布,向南东方向侧伏。断裂的膨胀部位是矿化富集的有利位置,构成了厚大的金矿体,多个豆荚状金矿体的断续分布构成了大坪金矿。金矿床的侧伏方向与矿脉的斜深延伸方向一致。在空间上,分段富集、局部集中,分布间距相似,形成矿化富集中心和矿化富集带。矿体厚度中心与矿体浓度中心相吻合。矿脉延伸指示成矿流体运移方向为南东——北西方向,矿化富集具有一定的侧伏规律,由北西方向往南东方向深部侧伏。(2)依据构造透镜体和断层角砾的形态和空间分布,以及阶步和擦痕的联合分析,判断含矿断裂为左行剪切正断层。(3)韧性剪切带的石英EBSD组构分析显示,石英的变形温度为低温(400℃),反映本区经历了低温变形变质作用。(4)矿脉和断层产状投出的极射赤平投影图表明,矿脉形成于左行压扭性断裂中。本文详细讨论了控矿构造特征和矿体富集规律,这对深部成矿预测和扩大找矿远景具有重要意义。
[Abstract]:The Daping gold deposit is regarded as the most typical gold deposit in the southern section of the Ailaoshan orogenic belt, and the orebody is strictly controlled by the metallogenic fault structure.This area is characterized by frequent and intense tectonic activity, multi-period, long-term and inheritance.Structure not only controls the distribution of strata and emplacement of rock mass, but also strictly restricts the distribution of orebody, which makes it a dominant factor in ore control.The mineralization of the deposit is mainly controlled by the combination of the NNW-trending Xiaoxinjie fault and the NW-trending Sanjiahe fault from the NNW direction to the west of the deposit.The east vein is divided into east mineralization zone, the main body of study is NW direction V1-2-3 ore vein, the west vein is divided into west mineralized zone, the main body of study is NNW direction V9-8-14 ore vein.In order to study the tectonic kinematics characteristics, ore-controlling rules and metamorphic deformation of the vein, this paper mainly deals with the ore body shape, the occurrence of the vein, the shape and spatial distribution of the tectonic lens and fault breccia.The EBSD fabric analysis of quartz in the ductile shear zone has been carried out. The following results and the understanding of the geometry of the two veins have been obtained. The results show that the two veins are beaded on the plane.Pod-like distribution, the profile of geese and isometric distribution, south-east direction of lateral.The swelling part of the fault is a favorable position for mineralization and enrichment, forming a thick gold body, and the intermittent distribution of several pod-like gold bodies constitutes the Daping gold deposit.The lateral direction of the gold deposit is consistent with that of the diagonal extension of the vein.In space, the mineralization enrichment center and the mineralization enrichment zone are formed.The thickness center of the orebody coincides with the concentration center of the orebody.The ore-vein extension indicates that the direction of ore-forming fluid migration is in the direction of south-east-north-west, and the mineralization enrichment has a certain law of lateral potential. From the north to the west, the deep side of the ore-forming fluid is located in the direction of the south to the east) according to the shape and spatial distribution of the structural lens and the fault breccia.And the combined analysis of step and scratch shows that the ore-bearing fault is a left-lateral shear normal fault. The EBSD fabric analysis of the ductile shear zone shows that the ore-bearing fault is a ductile shear zone.The deformation temperature of quartz is 400 鈩，

本文编号：1709326