西准南部还原性斑岩铜钼矿构造背景与形成机制

发布时间：2018-02-02 15:06

  本文关键词： 包古图 宏远 还原性斑岩铜矿 构造背景 形成机制　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】：自Rowins(2000)首次提出还原性斑岩铜矿(RPCDs)以来,这类以发育大量岩浆阶段磁黄铁矿和成矿流体富CH4为主要特征、与钛铁矿系列花岗质岩石存在成因联系、矿化和蚀变规模较小的斑岩矿床在世界范围内不断被发现并引起越来越多的学者关注。近期研究发现,西准南部地区的包古图铜矿与宏远钼铜矿具有还原性斑岩矿床特征。然而,关于这两个矿床构造背景与成因机制的认识还存在争论,同时,关于西准南部地区构造单元属性与演化过程的认识也具有较大分歧。本文以西准南部地区构造演化、以及包古图与宏远斑岩矿床形成机制为主要研究对象,通过大量的野外地质调查与室内实验测试分析,结合前人研究成果,获得以下研究进展:(1)划分西准地区构造单元,以谢米斯台断裂为界分为南北两部分,六个构造单元,北部西准包括:萨吾尔大洋岛弧与谢米斯台弧,南部西准包括:巴尔鲁克弧、洋壳俯冲增生杂岩带、包古图弧与拉巴地体;(2)提出巴尔鲁克早泥盆-晚石炭世陆缘弧、拉巴晚奥陶-中志留世陆缘弧与包古图石炭纪大陆岛弧,并限定这三个弧的俯冲结束时间分别为302Ma,410Ma与321Ma;(3)在包古图矿区识别出富铜辉长岩,指出基性岩浆对矿区成矿具重要贡献;(4)建立了宏远矿区蚀变与矿化分带结构,发现富黄铜矿与磁黄铁矿岩浆-流体囊,指出宏远矿床为新型还原性性斑岩钼铜矿,成矿作用经历了晚期岩浆-热液阶段(400~440℃)流体氧化还原环境发生突变成矿、及热液阶段(160~200℃)降温、降压成矿;(5)建立西准南部地区构造演化与成矿模型,指出后碰撞阶段加厚下地壳拆沉-软流圈地幔上涌与基性岩浆的参与,是形成还原性斑岩铜钼矿的重要条件。
[Abstract]:Since Rowins2000 first proposed the reductive porphyry copper deposit (RPCDs), this type is mainly characterized by the development of a large number of magmatic stage pyrrhotite and the rich CH4 of ore-forming fluids. The porphyry deposits with small mineralization and alteration scale have been found in the world and attracted more and more scholars' attention. The Baogutu copper deposit and Hongyuan molybdenum copper deposit in the southern part of West China are characterized by reductive porphyry deposits. However, the understanding of the tectonic background and genetic mechanism of the two deposits is still controversial and at the same time. There are also differences on the attributes and evolution process of tectonic units in the southern part of the western part of China. The tectonic evolution in the west of the region and the formation mechanism of the Baogutu and Hongyuan porphyry deposits are the main objects of study. Through a large number of field geological surveys and laboratory test and analysis, combined with the previous research results, the following research progress was obtained: 1) dividing the structural units in the West area into two parts, which are divided into two parts: the Shemis platform fault as the boundary and the north and south parts as the boundary. Six tectonic units, including the Sawuer oceanic island arc and the Schaemis platform arc to the north, and the Baluk arc to the south, the oceanic crust subducting accretive complex belt, the Baogutu arc and the Raba terrane to the west; (2) the early Devonian and late Carboniferous continental margin arc in Balluk, the late Ordovician margin arc in Raba and the Carboniferous continental island arc in Baogutu are proposed, and the subduction ending time of these three arcs is defined as 302Ma. 410Ma and 321Ma; (3) the copper-rich gabbro is identified in Baogutu ore area, and it is pointed out that the basic magma has an important contribution to the ore-forming of the ore area. (4) the alteration and mineralization zonation structure of Hongyuan ore area has been established, and the rich chalcopyrite and pyrrhotite magma fluid sac have been found. It is pointed out that the Hongyuan deposit is a new type of reductive porphyry molybdenum copper deposit. The ore-forming process experienced the late magmatic hydrothermal stage (400 ~ 440 鈩，

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