胶东西北部花岗岩构造地质特征与大尹格庄金矿成矿规律研究

发布时间：2018-01-25 23:55

  本文关键词： 构造岩相 界面成矿 郭家岭花岗闪长岩 大尹格庄金矿床 胶东西北部　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：胶东是我国最重要的黄金产区之一,金矿成矿受中生代花岗岩及断裂构造控制。本文围绕胶西北郭家岭花岗闪长岩构造地质特征与区域构造背景的关系、构造作用通过影响金矿成矿的物理化学条件并进而影响成矿地球化学过程等问题,开展郭家岭花岗闪长岩构造地质特征、区域及典型矿床构造岩相控矿特征等研究,获得以下认识:(1)胶西北郭家岭岩体及围岩内部似片麻理走向为NW~NNW向,接触带似片麻理走向与接触带走向近一致;岩体中钾长石斑晶长轴走向为NW和NNE向,二者夹角110°~120°,岩体西南部斑晶密度较大、a轴长度较小,岩体东北部斑晶密度较小、a轴长度较大,斑晶密度和a轴长度等值线呈NW向展布;显示郭家岭岩体主动侵位特点,揭示岩体在强力挤压状态下侵入,最大主压应力方向为NE向。(2)郭家岭岩体岩石显微组构分为岩浆-高温固态流动组构、中温固态流动组构和低温固态流动组构,据此将岩体分为高温、中温和低温构造岩相带,各带呈NW向展布;石英C轴EBSD组构特征显示:高温、中温和低温构造岩相带石英变形温度为450~550℃、350~450℃和250~350℃,分别通过柱面(1010)0001、柱面(1010)1210和底面(0001)1120滑移系蠕变;钾长石斑晶a轴长度较大区域位于高温岩相带,密度较大区域位于低温岩相带。(3)胶西北地区构造蚀变围绕控矿断裂发育,构造蚀变带展布与断裂带基本一致,自断裂带向外构造蚀变逐渐减弱,且断裂下盘更发育,金矿一般赋存于黄铁绢英岩带。通常含矿区段蚀变带较宽,蚀变带较窄或无蚀变区段不含矿。(4)大尹格庄金矿床构造蚀变带流体包裹体完全均一温度为148~310℃,盐度为1.71%~12.71%;成矿流体富含CO2;阴阳离子主要为SO42-、F-、Ca2+、Na+,成矿流体为中低温、低盐度CO2-H2O-NaCl体系。氢氧同位素分析表明成矿流体主要来源于岩浆混合水。(5)大尹格庄金矿床构造蚀变带岩石应力应变分析表明:自断裂带向外黄铁绢英岩、黄铁绢英岩化花岗质碎裂岩和钾化花岗岩变形石英a/c轴比均值为2.495、2.8415和2.5323,ac面差应力均值为283.54×105Pa、361.18×105Pa和276.68×105Pa,a/c轴比值和差应力值均先升后降;在此基础上测得构造蚀变带构造附加静水压力为(821.90~1156.48)×105Pa;经构造校正测算获得矿床成矿深度为-2775.4~-4164.5m。(6)建立了大尹格庄金矿床构造岩相界面成矿模式。显示构造力集中和松弛部位分别对应其他物理化学参量高值、低值区,高低值转变带存在有利于成矿的构造物理化学界面带,成矿发育于构造力松弛一侧。
[Abstract]:Jiaodong is one of the most important gold-producing areas in China. Gold mineralization is controlled by Mesozoic granite and fault structure. This paper revolves around the relationship between tectonic geological characteristics and regional tectonic setting of Guojialing granodiorite in northwestern Jiao. Tectonism develops the tectonic geological characteristics of granodiorite in Guojialing by influencing the physical and chemical conditions of gold mineralization and further affecting the process of mineralization and geochemistry. Based on the study of tectonic facies and ore-controlling characteristics of regional and typical deposits, the following conclusions are obtained: (1) in Guojialing rock mass and surrounding rock mass in northwestern Jiao, the trend of NW~NNW is similar to that in the inner part of Guojialing rock mass. The contact zone is similar to that of the contact zone. In the rock mass, the long axis strike of potash feldspar porphyry is NW and NNE, the angle between them is 110 掳~ 120 掳, the length of porphyry axis is larger in the southwest part of the rock mass, and the porphyry density is smaller in the northeast part of the rock mass. The length of a axis is large, and the isopleth of porphyry density and a axis length is distributed in NW direction. It shows the characteristics of active emplacement of Guojialing rock mass, and reveals that the rock mass invades under the condition of strong compression, and the direction of the maximum principal compressive stress is NE. 2) the rock microstructure of the Guojialing rock body can be divided into magma and high temperature solid flow fabric. According to the medium temperature solid flow fabric and the low temperature solid flow fabric, the rock mass is divided into high temperature, moderate and low temperature tectonic facies belts, each of which is NW distributed; The EBSD fabric characteristics of quartz C-axis show that the deformation temperature of quartz in the tectonic facies belt of high temperature, moderate temperature and low temperature is 450 ~ 550 鈩，

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