西秦岭东部金矿成矿模式和找矿方向

【作者】 韩要权；

【导师】 奚小双；

【作者基本信息】 中南大学 ， 地质工程， 2004， 硕士

【摘要】 西秦岭区带处于十分独特的构造环境，具有良好的成矿地质条件，找矿潜力巨大。从该区的李子园、礼岷、西成等主要金矿化集中区的找矿来看，各矿化集中区内尽管不同程度的发现了一些金矿床，但大部分为露头矿，隐伏矿较少。随着地质工作的不断深入，找矿难度越来越大，同时部分老矿山资源已接近枯竭，需要寻找新的后续资源。此外，由于在计划经济下相对单一的地质找矿，仅对某一矿种或矿床进行工作，缺乏宏观的、系统性的综合研究，对区内不同类型、不同矿种之间的成因联系研究不足，导致认识上的不完善。因此，弄清该区的金矿成矿特征及矿化规律，结合地质演化的分析，建立成矿模式，确定区内金矿找矿方向，开展新矿区找矿和老矿区外围及隐伏矿的找矿是本区矿产勘查的新目标。 本论文的研究工作通过区域调查和测定地质剖面，了解区内总体构造框架；结合新理论、新认识，分析该区地质演化过程，研究区域成矿作用；进一步对已有矿床进行调研，开展综合研究，建立成矿模式，确定区内金矿找矿方向。 本论文的研究成果和认识有：确定了西秦岭在泥盆纪海西运动时发育了相当规模的裂谷构造，产生了海底热水喷流作用，形成了沉积型铅锌矿层和含金碎屑岩层；在三叠纪末的印支运动产生碰撞造山，形成了一系列的推覆构造，并伴随着大量的岩浆活动，不但对已形成的铅锌矿层进行了改造或再造，而且使地层中的金元素发生了活化、富集，初步形成了区内的金矿；在燕山期由于太平洋板块发生由南东向北西的俯冲，形成了以断裂和花岗岩活动为特征的构造热事件，使构造带中的金元素进一步活化、迁移，在有利的扩容构造中沉淀成矿或叠加于已形成的矿体上改造成矿。该区金矿化集中区主要有李子园、礼岷和西成矿化集中区。区内金矿化类型分为断裂破碎带型、破碎带—蚀变岩型和石英脉型三大类。西秦岭东部金矿成矿经历了加里东期、海西期、印支期及燕山期四个阶段，加里东期形成了主要的矿源层—李子园群绿片岩，海西期伴随西成铅锌矿的产生，形成了西成地区的金矿源层—西汉水组碎屑岩，在礼岷地区沉积了又一金矿源层—李坝群碎屑岩，印支期主要是对铅锌矿的改造，同时形成了西成断裂带型金矿、李子园石英脉型金矿等，并使礼岷一带的破碎带型金矿硕十学位论文西秦岭东部金矿成矿模式和找矿方向产生预富集，在燕山早期随着岩浆活动的结束，区内金矿最终成矿，并伴随铜钥多金属矿的产生。 总之，西秦岭东部金矿化主要分布于李子园群绿片岩、李坝群碎屑岩及西汉水组千枚岩中;矿化体主要形成于印支期一燕山期侵入岩体的内外接触带及断裂构造带中，石英脉型金矿主要形成于岩体接触带附近，破碎带型、蚀变岩型金矿主要形成于岩体外1一5千米范围内;不论岩浆成因还是构造成因，金矿体均受断裂破碎带、断层带或片理化带等构造带控制，产于大断裂带旁侧。在该区今后找金应以“李坝式”和“大沟里式”为主。更多还原

【Abstract】 West-QinLing metallization belt take to be placed in the very special tectonic background, have good mineral-forming condition and great prospection potential. Although prospector have founded some gold-ore deposits to some extent in some gold metallization concentrate area, such as LiZiYuan, LiMin, XiCheng,etc, among these deposits, most are located in the earth’s surface, less in underground. With continuously prospect work, the prospection are more difficulty, at the same time, the resources of most of mine have nearly dried up, it need to look for new resources. In addition, single geological prospection plan which only prospect certain type ore or deposit under the planned economy, lacking macroscopic and systemic research, lacking contact research between different type ore and different mine, cause the cognition is not perfect. Therefore, the purpose of this work primarily is establish metallization mode and find direction of prospection and do prospect work in new prospect area and old prospect area, basing metallization law and metallization characteristic of the gold mine and analyse of geological evolution.The research method of this work is: survey geological section to understand the framework of tectonics; analysis geology process and study region metallization function by new theories and new cognition; establish metallization mode and find direction of prospection basing synthesize research and investigation of the deposits.The research results is as followed: (i) The west QinLing had grown rift at Devonian period in the HaiXi movement, which produced exhalation of the hot water of bottom of sea, forming sedimentation-type lead-zinc ore layer and gold-hosted clastic sediment; (ii) At the end of Permian period in the YinZhi movement, collision orogeny produced a series of nappe, accompany with lots of magma activity, not only reformed the layer of formative lead-zinc ore but also made the gold element activate and gather from the geologic strata, and the gold mine come into being in the area; (iii) In the YanShan movement , Pacific Ocean plate subducted from south-east to west-north, which producedtectonic hydrotherm event of characteristic of fracture and granite activity, and made the gold element in the structure zone activate and transfer which deposite in the enlarge structure or reform pre-orebody.The area’s gold metallization primarily concentrate in LiZiYuan area, LiMin area, and XiCheng area etc. The type of gold metallization in the area is divided three types: fracture type, fracture-alteration type and Quartz-vein type. The evolution of the eastern region of West-QinLing have four process: JiaLiDong period, HaiXi period, YinZhi period, YanShan period. In the JiaLiDong period, it produced the main ore-resource layer-LiZiYuan group greenchist. In the HaiXi period, it produced XiCheng lead-zinc deposits and XiCheng ore-resource layer-XiHanShui group clastic, and produce another gold ore-resource layer-LiBa group clastic in the area of LiMin. In the YinZhi period, reformed the lead-zinc deposits, at the same time, produced XiCheng fracture-type gold mine, LiZiYuan Quartz-vein type gold mine and made fracture-type gold mine in the area of LiMin pre-gather. In the early of YanShan period, LiMin fracture-type gold mine is produced, and following Cu, Mo poly-metallic ore deposit produced with the end of the magma activity .In a word, gold metallization in the eastern region of West QinLing primarily distribute in the LiZiYuan group greenchist, LiBa group clastic and XiHanShui group nhyllite; gold metallization body mainly location in the fracture zone and inside and outside contact zone of invading rockbody of YinZhi period and YanShan period, and fracture type, fracture-alteration type orebody location outside of invading rockbody in the range of 1 -5 thousand; Whether magma reason or structure reason, the gold mine is all controlled by fracture zone beside large fracture. We should find " LiBa type" and " DaGouLi type" gold mine in the district.更多还原