【作者】 许运涛；

【导师】 魏刚锋； 雷星明；

【作者基本信息】 长安大学 ， 构造地质学， 2010， 硕士

【摘要】 白河酒馆沟磁铁矿矿床位于南秦岭印支褶皱带金鸡岭-留风关褶皱束东南端与白水江-白河褶皱束东北缘接触带,隶属于南秦岭徽县-旬阳地层分区,为近年来在陕南地区新勘查发现的磁铁矿矿床,与西侧的张河磁铁矿和平定河磁铁矿为同一类型,共同组成一近东西向的矿带。矿床呈东西向带状分布,东西追索长度约40km,南北宽约2.5km,面积约100km2。根据野外地质调查,研究区现已发现4条磁铁矿矿体,TFe平均品位约20%,7个褐铁矿化体,具有较大的潜在经济价值。本文依托2007-2009年1：1万陕西省白河县酒馆沟磁铁矿矿产普查最新成果,对白河酒馆沟磁铁矿床的地层进行划分,构造格架进行厘定；研究了矿区内韧性剪切带的几何学、运动学、动力学及演化特征,认为韧性剪切带是研究区磁铁矿的主要控矿因素。从而初步阐述磁铁矿矿床的控矿地质条件及其成因类型,探索其成矿远景和找矿潜力。本论文取得的主要成果如下：1.区内矿带分为南、北2条,即倒转向斜两翼各1条,大致对称展布,以中泥盆统第二岩性段(D2S2)为主,圈定磁铁矿体4个,褐铁矿化体7个。矿石主要为磁铁矿,其次为褐铁矿、菱铁矿及微量黄铁矿、黄铜矿、磁黄铁矿、赤铁矿。矿石结构主要为它形-半自形粒状结构,以条带状构造为主,块状构造次之。2.矿区内南北矿带分别受两条近东西向韧性剪切带控制,剪切带经历了多期变形,主要有3期：早期形成糜棱岩带,相当于绿片岩相动力变质作用,可见S-C组构,垂直拉伸方向有长英质脉产出,南部控矿剪切带为左行压扭性剪切,北部控矿剪切带为右行压扭性剪切,σ1≈192°∠10°,古应力值约19.2MPa；两控矿剪切带中期经历了右行张扭性韧脆性剪切作用,形成剪切褶皱和鞘褶皱,并有石英脉充填,σ1≈36°∠15°,古应力值约0.42MPa；晚期经历了较弱脆性扭张,表现为石英脉局部强烈破碎。3.对区内成矿地质背景、成矿地质条件进行了分析,认为白河酒馆沟磁铁矿矿床形成发展经历了3个阶段：第一阶段(菱铁矿的形成阶段),中泥盆统石家沟组正常水成沉积中的铁碳酸盐物质在还原环境和区域变质作用下形成细晶菱铁矿；第二阶段(细粒磁铁矿的形成阶段),形成的细晶菱铁矿在区域变质作用和早期韧性剪切作用叠加的部位形成细粒磁铁矿；第三阶段(粗粒磁铁矿的形成阶段),早期形成的细粒磁铁矿在后期张扭性韧脆性剪切作用和后期变质热液参与下活化、迁移,并在韧性向韧脆性过渡的部位富集成矿。矿床的控矿因素呈现“层控+褶皱+韧性剪切带”复合叠加特征。矿床成因类型为沉积变质-动力热液改造复合型铁矿床。4.利用区域已有物探、化探资料,结合地质研究,进行综合分析,认为该区最具成矿潜力的地段是南矿带的Fe2、Fe3矿体以及矿区西部相邻同一构造层位。更多还原

【Abstract】 Magnetite deposit is located in White River pubs ditch Indo-China, South Qinling fold belt Jinjiling-Fung Kwan left side and fold beam Southeast Baishuijiang-Shirakawa fold beam northeastern margin of the contact zone, belonging to the South Qinling Hui County-Xunyang stratigraphic area. It is a magnetite deposit found in the Southern region found in the new exploration, which is the same type of Zhanghe River magnetite and Pingding River magnetite in the west side, and they together constitute an E-W belt. The distribution was like belt, with a length of about 40km,north-south width of 2.5km,and an area of about 100km2. According to field investigation,four of magnetite ore had been found in this area,and the average grade of TFe is about 20%,also with 7 limonitization body. All of the discoveries implied a great potential economic value.This paper relies on the latest achievements of the White River area pubs ditch of 1:1 million magnetite Mineral in Baihe County of Shanxi Province from 2007 to 2009 and the magnetite formation is divided for determining the structural framework; With the study of the mining area of deformation within the ductile shear zone, movement, evolution, we conclude that the shear zone in the study area is the main ore-controlling factors of magnetite. Thus it initially sets forth the geological conditions and their causes of magnetite ore deposit and explore their metallogenic and prospecting potential. Main achievements of this paper are as follows:1. With the belt region is divided into North and South, that all wings of a reverse syncline, roughly symmetric distribution. With Middle Devonian second lithologic (D2S2) mainly divided into two belt, with 4 delineated magnetite body,7 limonite of body. Minerals are mainly magnetite, followed by limonite and trace pyrite,chalcopyrite, pyrrhotite, hematite, ilmenite. The main ore structure for its shape-half from the shape of granular structure to the main bandedstructure, block structure second.2. The north-south mining area of the belt were controlled by two ductile shear zones from east to the west, and the shear zone has been through a number of deformation, with obviously three main:During the early one the mylonite belt was formed, which is equivalent to low-amphibolite facies metamorphism, S-C fabric was also found, in the vertical tensile direction there are felsic veins, shear zones in southern ore was left transtension of shear, shear zone north of ore for the right line of pressure-shear shear,σ1≈192°∠10°, Ancient stress value of about 19.2MPa; two ore shear zone experienced a mid-line of the right of ductile-brittle shear-shear effect, the formation of shear folds and sheath folds, and a quartz vein filling,σ1≈36°∠15°ancient stress value of about 0.42MPa; late brittle transtensional experienced weak, showing a strong quartz vein partial fragmentation.3. With the region’s geological background and analysis of geological conditions, we conclude that the White River magnetite deposits pub trench formation and development has gone through three stages:The first stage (the formation of siderite phase), in the Middle Devonian Shijiagou group of normal deposition of iron in aqueous carbonate material in the reducing environment formed by regional metamorphism and fine-grained siderite; The second phase (fine-grained magnetite formation stage), the formation of fine grain siderite in the regional metamorphism role and the role of early ductile shear superimposed formed part of fine magnetite; The third stage (the formation of coarse-grained magnetite phase), early formation of fine-grained magnetite in the post-shear of ductile-brittle shear and the participation of late metamorphic hydrothermal activation, migration, and toughness to the ductile-brittle transition in the site enrichment andmineralization.Ore-controllin-factors ore body showing composite overlay of "stratabound+ fold+ ductile she ar zone, " The causes of it were genesis of sedimentary metamorphic type-dynamic transfor-mation of complex hydrothermal iron deposits.4. The area’s most promising regions are South mineralization belt containing the Fe2, Fe3 ore body and mine the same structural layer adjacent to the west bit, using regional geophysical and geochemical data, combined with knowledge of geological research, and comprehensive analysis.更多还原