南秦岭汉阴北部金矿田陆内造山期构造—岩浆—成矿规律及成矿模式研究

发布时间：2018-03-19 04:04

  本文选题：南秦岭　切入点：燕山期　出处：《长安大学》2017年博士论文　论文类型：学位论文

【摘要】：秦岭造山带作为复合型、多旋回的大陆造山带一直以来都是地学界关注的热点,有关秦岭造山带的研究很早就已展开,并积累了大量的认识成果。普遍认为其是扬子板块和华北板块共同作用的结果,多阶段造山运动和构造热事件引起秦岭造山带内发生了一系列的成矿作用。南秦岭构造带是秦岭造山带中规模最大、发展演化复杂的构造单元,也是秦岭造山带的主体。南秦岭地区分布的矿产资源类型丰富,其中金矿资源储量可观,继续深入对南秦岭地区展开研究有助于取得更大的找矿成果。此外,三叠纪以后的“陆内造山”阶段对南秦岭地区具有划时代的意义,而前人对该阶段的研究相比印支期板块碰撞造山阶段明显偏弱,因此有必要加强对陆内造山期的构造-岩浆-成矿事件研究。矿田(金属矿田)是在空间、时间、构造建造及成因上相类似的一些矿床及矿化点集中赋存的区域,其指示为成矿作用集中发育的地质单元。通过矿田地质学研究可以有效掌握矿田尺度上各矿床与矿体的形成特点、分布特征及改造规律等,对矿产资源的勘探开发具有着重要意义。南秦岭汉阴北部金矿田位于南秦岭构造带的中部,东西长约50km,南北宽约10~20 km,为陕西石泉-汉阴-旬阳金矿整装勘查区内的一个重要矿田。近年来矿田内已经探明数十处规模不等的金矿床。然而随着探矿工程的不断深入,金矿的勘查工作明显遇到了一定的瓶颈,迫切需要进一步的理论研究来指导生产实践。此外对于该区金矿的成矿类型多有争议,对矿田内广泛分布的岩浆岩脉重视不够,尤其岩浆岩同金矿之间的关系几乎未见讨论。本论文以中国地质调查局《陕西石泉-旬阳金矿整装勘查区专项填图与技术应用示范》项目为依托,以汉阴北部金矿田为研究对象,在充分搜集、分析和研究前人成果的基础上,首先通过野外对典型矿区进行大比例尺构造-岩相填图、实测剖面与探矿工程测量等,查明了矿田的岩石地层特征、构造变形样式、矿床地质特征和矿化蚀变信息等;其次,通过室内大量的综合研究和编图等工作,进一步掌握了矿田构造特征及各主要控矿要素特点;此外,通过大量采集各类岩石和矿石样品,进行实验室分析和测试,明确了与金矿成矿作用相关的各类信息;基于以上工作,进行深入分析和总结,明确了矿田内金矿的成矿规律及成矿模式。取得成果如下。(1)汉阴北部金矿田内可划分出五条近东西向、北西向展布的大型脆-韧性剪切带,其形成的时代为早侏罗世开始的陆内造山阶段,形成的环境为矿田南北两侧的宁陕和安康断裂发生大规模走滑剪切运动、中间块体整体向东挤出。(2)矿田内五条大规模的脆-韧性剪切带为成矿期构造,其控制着各金矿床的空间分布位置,而脆-韧性剪切带内的次级断层破碎带则控制了金矿体产出的具体部位。(3)矿田内的构造变形面理大致可划为三期,以S2面理占绝对主导,S2面理对金矿具有显著控制作用,属成矿期构造。(4)岩浆岩的锆石U-Pb同位素测年显示观音河花岗闪长岩侵位时代为180.2±3.6 Ma,柳坑细晶花岗岩形成时代为176.0±1.9 Ma,均属早燕山期,而岩浆岩同构造侵位于S2面理则指示了S2面理也形成于该时期,并且岩浆热液活动参与了金矿的成矿,且可能为成矿作用提供部分物源。(5)典型矿区不同期次石英脉流体包裹体研究表明,矿田内金矿的成矿温度大体介于190~300℃,属中-低温成矿,成矿压力范围大约为20.61~100.77 Mpa,成矿深度范围大约为0.76~3.74 km。(6)明确了金矿田内成矿物质主要来源于梅子垭组原始沉积地层,成矿期构造脆-韧性剪切带和S2面理形成于燕山早期的信息指示了成矿时代为早燕山期,主要成矿作用动力机制为韧性剪切作用。(7)明确汉阴北部金矿田的成矿类型为韧性剪切蚀变岩型并叠加岩浆期(后)热液,建立汉阴北部金矿田成矿模式演化图,并提出找矿思路和指明找矿方向。本研究成果能够为汉阴北部金矿田及邻区未来的金矿找矿勘探工作提供重要的参考价值和理论指导,有助于获取更多的金资源量。
[Abstract]:The Qinling Mountains orogenic belt as a complex, multi cycle orogenic belt has always been to focus in the academic circles, the study of the Qinling Mountains orogenic belt is already started, and accumulated a lot of understanding of the results. It is generally thought that it is the result of Yangtze plate and North China plate, multi stage and orogeny the tectonic thermal events caused by the mineralization of the Qinling Mountains orogenic zone. A series of southern Qinling Mountains tectonic belt of Qinling Mountains orogenic belt is the largest, the evolution of tectonic unit complex, is also the subject of the Qinling Mountains orogenic belt in southern Qinling Mountains. The distribution of mineral resources are abundant, the gold resource reserves, to continue in-depth study will help to achieve greater prospecting results of South Qinling Mountains area. In addition, the later Triassic intracontinental orogenic stage of southern Qinling Mountains has epoch-making significance, and previous studies on this phase Than the Indosinian plate collision orogenic stage was weak, so it is necessary to strengthen the research on the tectonic intracontinental orogenic period of magmatic events. Ore field (metal ore field) in space, time, some deposit and mineralization formation and tectonic origin of similar concentration occurrence area, indicating the geological unit concentrated ore the role of development. Through the study of ore field geology can effectively grasp the scale of the deposit formation characteristics of ore field and the ore body, the distribution characteristics and transformation rules, exploration and development of mineral resources has important significance. In southern Qinling Mountains, northern Hanyin, located in the southern Qinling Mountains gold ore field tectonic belt in the middle, something about 50km, north-south width of 10~20 km, Shaanxi - Hanyin - Xunyang Shiquan gold mine exploration is an important field in the region. In recent years the ore field has proven dozens of different scale gold deposit. However, with the continuous exploration engineering Further, the exploration of gold was encountered a bottleneck, further theoretical research urgently needed to guide the production practice. In addition to the metallogenic types of gold deposits in this area have much controversy, magmatite veins are widely distributed in the gold field is not enough, especially the relationship between magmatite with gold almost no discussion. In this paper, China the geological survey of "Shaanxi Shiquan - Xunyang gold mine exploration area special mapping and application demonstration > project, in northern Hanyin gold field as the research object, in the full collection, analysis and research based on the previous research, first through the field of typical mining area of large scale tectonic lithofacies mapping, measured profiles and exploration engineering measurement, rock formation characteristics of ore field to identify the tectonic deformation style, geological features and mineralization alteration information; secondly, through a lot of comprehensive research and The mapping work, and further understand the characteristics of orefield structure and major ore controlling factors; in addition, by collecting a large number of various types of rock and ore samples, laboratory analysis and testing, the various kinds of information related with gold mineralization; based on the above work, in-depth analysis and summary, the metallogenic regularity and model of ore field gold. The results are as follows. (1) can be divided into five nearly East-West to the north of Hanyin gold field, North West to the large scale distribution of brittle ductile shear zone, intracontinental orogenic stage of the formation of the early Jurassic era began, the formation of healthy environment for Ningshan and the South and north sides of fracture field the occurrence of large-scale strike slip movement, the middle block overall eastward extrusion. (2) in the ore field five large-scale brittle ductile shear zone is metallogenic structure, the spatial distribution of the position control of all gold deposit, and brittle 闊ф，

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