甘肃北山公婆泉铜矿成矿环境及其矿床成因类型探讨.pdf

Metallogenic environment and discussion ic type of Gongpoquan copper deposit,in BeishanArea,GansuProvince A Dissertation Submitted for the Degree of Master Candidate:Yang Hui Supervisor:Prof. Jiang Xiudao Chang’an University, Xi’an, China i 摘要公婆泉铜矿构造位置特殊,矿床地质特征复杂,历来颇受关注。经过多年的研究和勘探开发,积累了一批宝贵的研究成果和资料,但在成矿环境和矿床成因类型方面仍然存在一些重大科学问题。本文通过近两年的野外调研,并结合室内岩矿石光薄片鉴定以及常量元素、稀土元素和微量元素的测试分析,综合研究和探讨公婆泉铜矿的成矿环境和矿床成因类型,主要取得了以下几点认识: 1、通过野外调研,在矿区厘定了三条韧性剪切带,展布方向分别为NEE、NWW 和NNW,研究表明,它们是公婆泉铜矿的成矿构造,同时控制着矿体的形态、产状。 2、矿区的三条韧性剪切带对应地分为三期,每一期构造活动都伴随着岩浆活动并成矿。第一、二期构造活动成矿特点基本相同,主要形成细粒浸染状矿石,及少量细脉浸染状构造的矿石,第三期则形成团块状、脉状矿石,正是由于多期次的矿化叠加从而导致了团块状富铜矿石的形成。 3、通过对矿区基性-超基性岩的常量元素、稀土元素和微量元素特征研究,结合矿区构造格局及岩浆岩特点,综合研究认为这些基性-超基性岩块为蛇绿岩,其形成于消减带之上的弧后盆地构造环境,因此公婆泉铜矿的形成与弧后盆地有关。 4、矿区发育一些通常规模很小的呈小岩枝或岩脉产出的斑岩体,可称之为(超) 小岩体,这些(超)小岩体有的发育矿化,有的则不发育,矿体的空间分布与斑岩没有明确的依存关系。 5、通过与国内外典型矿床的对比研究,公婆泉铜矿在矿体形态、产状,控矿机制、围岩蚀变类型及空间分布、矿石结构构造等方面与典型斑岩型矿床有较大出入,同时结合韧性剪切带构造控矿和成矿的多期次性,认为该矿床从岩浆岩与成矿的关系上讲为受韧性剪切带和岩浆作用共同控制的叠生矿床,而从主导控矿因素来讲为剪切带型铜矿床。关键词:北山,公婆泉铜矿,韧性剪切带,蛇绿岩,弧后盆地,矿床成因类型 iii Abstract Gongpoquan copper deposit is very popularall through the ages because of its special geological features of tectonic position plex geological characteristics. After years of researches and explorations, there are a number of valuable research results and data have been in the field of metallogenic environment and its ic type of ore deposit,some important scientific problems are still existed ,waiting to be solved. This paper regards the two year’s work of field investigation as the dominant, combining with laboratory research in rock and ore microscope observation and research as well as the major elements, the rare earth elements(REES)and the trace elements test analysis,to research and discuss the metallogenic environment and ore genesis type of Gongpoquan copper achievements have been made in the following points: the field investigation, there are three ductile shear belts in the mini