青海北祁连尕大坂地区黑矿型矿床特征及成矿环境探讨

发布时间：2018-04-04 04:29

本文选题：北祁连　切入点：黑矿型　出处：《青海大学》2015年硕士论文

【摘要】：北祁连造山带是中国较为重要的铜多金属成矿带之一,除了镜铁山式沉积型铁矿外,与海相火山作用有关的铜多金属块状硫化物矿床(VHMS或VMS)是主要的成矿类型。北祁连早古生代VHMS型铜多金属矿床按其成矿环境、赋矿岩石和成矿元素组合可分为两大类型:一类是与基性火山岩有关的“塞浦路斯型”VHMS矿床,主要分布在走廊南山北坡的火山岩中,以石居里沟为代表矿床,形成环境为弧后盆地扩张环境;另一类是与中酸性火山岩有关的“黑矿型”VHMS矿床,主要分布于北祁连造山带的东段和西段,以白银厂和尕大坂为代表,成矿环境与大陆裂谷环境或岛弧张裂环境有关。由于近年来对北祁连尕大坂地区的不断勘探,发现尕大坂和郭米寺矿床已达中型规模,认为这两个矿床对该地区“黑矿型”矿床的研究有代表意义。北祁连造山带的黑矿型块状硫化物矿床主要分布在走廊南山南坡的火山岩带中。尕大坂矿田的矿床具有世界黑矿型块状硫化物矿床的典型特征,矿床集中分布,具分层性,围岩蚀变现象明显。这些矿床主要沿着大柳沟-白柳沟火山穹窿的蚀变带两翼的基性和酸性火山岩过渡带产出,严格受蚀变带控制。矿床含有热水喷流岩及其与之相伴的含碳黑色岩系,这种岩石组合普遍存在于热水喷流矿床中,称之为“双岩石组合”,是典型的海底热水喷流沉积的标志,并可作为判断黑矿型块状硫化物矿床的一种标志性岩石组合。矿床的成矿元素以Pb、Zn、Pb为主,矿石类型为Zn-Pb-Cu型或Pb-Zn-Cu型,属黑矿型块状硫化物矿床;将尕大坂矿田中的温度、盐度与世界典型黑矿型矿床对比研究后,认为该矿田成矿流体的来源可能是岩浆热液与海水的混合。本论文采集了尕大坂矿田中寒武世黑茨沟组火山岩的岩石化学样,并做了主量元素、微量元素、稀土元素的测试。这些测试数据与收集的火山岩数据进行了分析研究,认为属弧后裂谷环境,对阐明与海相火山岩有关的黑矿型块状硫化物矿床的成矿特点和研究区的找矿前景具有指导性意义。
[Abstract]:The North Qilian orogenic belt is one of the most important copper-polymetallic metallogenic belts in China. In addition to the ophiolite sedimentary iron ore deposits, the copper-polymetallic massive sulphide deposits related to marine volcanism are the main metallogenic types.According to its metallogenic environment, the early Paleozoic VHMS copper polymetallic deposits in North Qilian can be divided into two types: one is the "Cyprus type" VHMS deposit, which is related to the basic volcanic rocks, and the other is the association of ore-bearing rocks and ore-forming elements.Mainly distributed in volcanic rocks on the northern slope of the south mountain in the corridor, Shicurigou is the representative deposit, and the forming environment is the back-arc basin spreading environment, the other is the "black ore type" VHMS deposit related to the intermediate and acidic volcanic rocks.It is mainly distributed in the eastern and western sections of the North Qilian orogenic belt, represented by Baiyinchang and GaOsaka. The metallogenic environment is related to the continental rift environment or the island arc extensional environment.As a result of the continuous exploration of the North Qilian GaOsaka area in recent years, it is found that the Gaidaban and Guomisi deposits have reached a medium scale. It is considered that these two deposits are of representative significance to the study of the "black ore type" deposits in this area.The black-ore massive sulphide deposits in the North Qilian orogenic belt are mainly distributed in the volcanic rock belt on the southern slope of the South Mountains in the Corridor.The Gadaban Orefield has the typical characteristics of the world black ore massive sulphide deposits. The deposits are concentrated and distributed with stratification and the wall rock alteration phenomenon is obvious.These deposits are mainly produced along the basic and acidic volcanic transitional zones of the alteration zone of the Daliugou-Bailiugou volcanic dome, and are strictly controlled by the altered zone.The deposit contains hot water exhalation rock and its associated carbonaceous black rock series. This kind of rock assemblage commonly exists in hot water jet deposits, which is called "double rock assemblage", which is the symbol of typical submarine hot water jet deposition.It can be used as an iconic rock assemblage to judge the black ore massive sulfide deposits.The ore-forming elements of the deposit are mainly PbPb-Zn-Zn-Pb, the ore type is Zn-Pb-Cu type or Pb-Zn-Cu type, which belongs to the black ore type massive sulphide deposit, the temperature and salinity of Gadaban Orefield are compared with those of the world's typical Kurothite deposits.It is considered that the source of ore-forming fluid in this ore field may be the mixing of magmatic hydrothermal fluid and seawater.In this paper, the petrochemical samples of the volcanic rocks of the Middle-Cambrian Heizigou formation are collected, and the main elements, trace elements and rare earth elements are tested.These test data and collected volcanic rock data are analyzed and studied, which is considered to be a back-arc rift environment, which is of instructive significance for elucidating the metallogenic characteristics of black-ore massive sulphide deposits related to marine volcanic rocks and the prospect of prospecting in the study area.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.2

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