大渡河韭菜坪石英脉型与蚀变岩型金矿对比及其成因探讨

发布时间：2018-02-22 04:02

本文关键词： 大渡河韭菜坪蚀变岩型石英脉型金矿　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：大渡河流域金成矿带韭菜坪金矿床位于鲜水河、龙门山与攀西裂谷三叉交会处,属于前震旦系康定杂岩中金矿床,赋矿围岩为斜长角闪岩和花岗闪长岩,是大渡河金矿带中石英脉-蚀变岩型金矿床的代表之一。矿床规模小型,具有较大远景。在地质工作过程中笔者发现,韭菜坪金矿床既发育有石英脉型金矿体,也有蚀变岩型金矿体。据初步观察两者在空间分布上存在着以下关系:矿床具有水平分带,即沿成矿的主构造带以蚀变岩型为主,远离主构造带以石英脉型为主;矿体具有垂直分带,即内有石英脉型金矿,外有蚀变岩型金矿;走向上的分带,即矿体的一段为石英脉型金矿,另一段为蚀变岩型金矿或以复合关系产出。为了弄清两种具有相似成矿环境的矿体各自的地质特征及成矿过程,进而探讨成矿作用之间的内在联系,为该区域内的找矿工作提出科学合理的建议,本文选择了韭菜坪金矿床进行了系统地矿床学研究。通过野外地质调查,室内镜下研究,矿体及围岩成矿元素测试分析,赋矿围岩及石英、黄铁矿等单矿物的微量元素测试分析,矿石硫化物硫同位素测试分析、石英ESR等方法对该矿床的系统综合研究,对韭菜坪矿床的成矿过程有了客观深入的理解:(1)韭菜坪金矿床矿石矿物成分均较简单,金属矿物以黄铁矿为主,脉石矿物以石英为主;(2)石英脉型和蚀变岩型与金成矿密切相关的黄铁矿、石英单矿物稀土元素配分模式具有一致性,均表现为平缓的右倾曲线且具有Eu负异常、Ce极弱异常的特征,表明韭菜坪金矿床的成矿流体形成的物理化学可能是相对还原性的环境,暗示了矿床的成矿流体可能属于中低温热液流体。另一方面,韭菜坪成矿期的石英包裹体均一温度范围相当,均集中分布于160℃~180℃,属于中低温热液流体;(3)韭菜坪黄铁矿δ34S值变化范围较小,δ34S值在2.5附近,组成较为稳定且均一化程度较高,与幔源硫较为接近,表明成矿流体具有地幔硫的特征;(4)通过石英活化ESR测年方法,测得韭菜坪金矿床的成矿年龄集中分布于17~13Ma,该时期对应于青藏高原后碰撞期(25~0Ma),表明韭菜坪金矿床属于后碰撞期剪切作用为主所形成时期的造山型金矿床;(5)两类矿化类型的空间分布与断裂性质有着密切的关系,蚀变岩型主要受控于高级别的缓倾角断裂带,以压性或压扭性为主,往往产于主干断裂中;石英脉型矿化主要受控于低级别陡倾角断裂带,以张性或张扭性为主,往往产于伴生或派生的小规模次级构造中。不同性质的断裂构造控制着不同类型的金矿,可以通过对不同类型金矿特征的研究,进一步研究控矿构造的性质,进而可以预测隐伏控矿构造和可能赋存的金矿床。综上所述,韭菜坪金矿床石英脉型和蚀变岩型矿体属于同一成因,由于构造条件和成矿作用方式不同而产生不同矿体形式。其成矿时代一致均为喜山期,成矿温度低,受韧-脆性剪切滑脱带控制。该矿床属于青藏高原东缘后碰撞晚期剪切作用所形成的造山型金矿,且处于造山型金矿的中部带。
[Abstract]:The Dadu River Valley metallogenic belt of Jiucaiping gold deposit is located in the fresh water river, Longmen mountain and the Panxi rift trigeminal intersection, which belongs to the pre Sinian Kangding complex rock gold deposit, ore rock amphibolites and granodiorite, is one of the representatives of the Dadu River gold belt in the quartz vein and altered rock type of gold deposit. The deposit scale small, has a great potential. The author found in geological work in the process of development of Jiucaiping gold deposit is quartz vein type gold ore bodies, have altered rock type gold deposit. According to preliminary observation and there is the following relationship in the spatial distribution of ore deposits is: Horizontal zoning, which is the main along with the metallogenic tectonic altered rock type, belt dominated by quartz vein type from the main structure; the ore body has vertical zoning, namely in the quartz vein type gold deposit, outside the altered rock type gold deposit; strike zoning, which is a section of the ore body is quartz vein type gold deposit, another for alteration Rock type gold deposit or compoundings. In order to find out the two kinds of ore similar metallogenic environment of their geological features and metallogenic process, and to explore the relationship between mineralization and put forward reasonable suggestions for the regional prospecting work, this paper chooses the leek Dongping gold deposit of mineral bed learning system the research. Through field geological survey, indoor microscopic study, analysis of orebody and surrounding rock metallogenic elements test, ore bearing rock and quartz, trace element analysis of pyrite minerals test, sulfur isotope analysis of sulfide ore testing system, a comprehensive study of the deposit of quartz ESR, metallogenetic process of Jiucaiping deposits with objective understanding: (1) Jiucaiping ore mineral composition is simple, the metal minerals are pyrite, quartz is the main gangue mineral; (2) quartz vein and altered rock type and The gold mineralization is closely related to pyrite, quartz mineral REE patterns are consistent, showed a gentle curve right and has very weak negative Eu anomaly, Ce anomalies, indicating that the physical chemical ore-forming fluid Jiucaiping gold deposit formation may be relatively primary environment, suggests that the ore-forming fluid the deposit may belong to low temperature hydrothermal fluid. On the other hand, Jiucaiping mineralization quartz inclusions are all concentrated in the range is 160 DEG ~180 DEG, which belongs to the medium low temperature hydrothermal fluid; (3) Jiucaiping pyrite 34S values changed a little, 34S values in the vicinity of 2.5. Stable and uniform degree is high, relatively close to the mantle derived sulfur, showed the characteristics of ore-forming fluids with mantle sulfur; (4) ESR dating method through the activation of quartz, the mineralization age measured Jiucaiping gold deposit concentration distribution in the period of 17~13Ma. Corresponding to the Qinghai Tibet plateau after the collision period (25~0Ma), showed that Jiucaiping gold deposit belongs to the post collision stage mainly formed by shear orogenic gold deposit period; (5) the spatial distribution of two types of mineralization type and fracture properties are closely related, altered rock type is mainly controlled by the high level of the low angle faults with pressure or compressoshear, often occurs in the main fracture; quartz vein type mineralization is mainly controlled by the low level of steep fault belt, with a tensile, small secondary structures often produced in the associated or derived. Distinct tectonic control of different types gold can, through the study of different types of gold deposits, further study on the properties of the ore controlling structure, which can predict the deposit concealed ore controlling structure and possible occurrence. In summary, Jiucaiping gold deposit of quartz vein and altered rock type ore body belongs to The same origin, due to tectonic conditions and mineralization in different ways and have different forms. Its orebody mineralization ages were consistent with Himalayan metallogenic temperature is low, the ductile brittle shear zone control. The deposit belongs to the eastern margin of the Tibetan Plateau after the formation of the late collision shear orogenic gold, and in the middle orogenic type gold deposit belt.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

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