青海东昆仑阿克楚克塞铜镍矿床地质特征及成因探讨

发布时间：2018-03-11 09:33

本文选题：东昆中基底隆起花岗岩带　切入点：地质特征　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：青海省东昆仑造山带截至目前,已发现了众多矿床(点),近年来随着地区内岩浆铜镍硫化物矿床的找矿突破,该类矿床的研究逐步深入。阿克楚克塞铜镍矿的发现是继夏日哈木镍矿后,该类型矿床找矿的又一重大突破,为区内岩浆型铜镍硫化物矿床的寻找提供了重要参照。阿克楚克塞铜镍矿位于昆中断裂北部的昆中基底隆起花岗岩带上。出露新元古代金水口群、寒武-奥陶纪滩间山群。断裂构造发育,主要有2条近北西向断裂F5和F6。断裂规模大,延伸远,2条构造均为压扭性质。区内岩浆岩主要是新元古代黑云二长片麻岩、早-中志留世的花岗闪长岩和镁铁质-超镁铁质杂岩、华力西-印支期的花岗斑岩、石英闪长岩和花岗岩等。阿克楚克塞地区先后发现了 5个基性-超基性岩体,其中Ⅰ、Ⅱ号岩体已开展大量工作,探槽及钻孔内可见较多的硫化物,可见表生的镍华与铜蓝,矿石品位较高。Ⅲ、Ⅳ、Ⅴ号岩体为17年新发现,从现已施工情况看,可见较多的硫化物,具有很好的成矿潜力。Ⅰ号岩体近SN向展布,倾向E,其内可见较多的滩间山群大理岩捕掳体。矿体长轴走向北北东,形态不规则,延伸不稳定,品位变化大。Ⅱ号岩体第四系覆盖严重,总体走向NE,倾向SE。Ⅱ号矿体向深部膨大、变厚、品位升高的趋势尤为明显。几乎所有样品高于0.1%,连续性好,出现了较高品位地段,并且出现了海绵陨铁结构等代表富矿石的现象。Ⅰ、Ⅱ号岩体含矿岩相主要为辉石岩相。岩体与大理岩间为切层侵入关系。镁铁-超镁铁质杂岩体为多期侵入而成,在深部岩浆房发生了硫化物熔离作用。在一定的动力学条件下,不含矿岩浆、含矿岩浆、富矿岩浆和矿浆依次脉冲式上侵,形成现今的浸染状和海绵陨铁状矿石。根据电子探针结果,辉石主要为单斜辉石类的顽透辉石,En61.64～-65.6,Fs7.74～10.74,Wo22.96-～26.01,为亚碱性系列里的拉斑玄武岩系列,形成于与弧有关的环境中。Ⅰ、Ⅱ号岩体即为矿体,这两个矿体具有相似的矿物组构。主要有镍黄铁矿(Pn)及镍华、黄铜矿(Cpy)及铜蓝、磁黄铁矿(Po),少量的紫硫镍矿、褐铁矿、黄铁矿及白铁矿。含钴的矿物未知,其存在形式为主要呈类质同相存在于镍黄铁矿中;矿石具特征的海绵陨铁结构、固溶体分离结构、自形-半自形粒状结构、他形粒状结构、不等粒结构和交代结构;星点状构造、斑杂状构造、团块状构造、浸染状构造,很少有块状构造、细脉状构造。岩矿石的硫同位素及S/Se研究表明,δ34S变化范围为6.7‰～11.5‰,偏离幔源硫0±2‰;S/Se比值为3738～15501,大于地幔平均值。以上表明岩浆从地幔上涌的过程中,有地壳硫的加入。对阿克楚克塞岩体辉石岩进行了 LA-ICP-MS U-Pb测年,厘定了其结晶年龄为422±10Ma,为中志留世。岩体的Zr/Nb比值为16.75～30.93,与MORB的Zr/Nb比值(10～60)比较接近,Sm/Nd比值为0.18～0.25,基本与MORB的范围(平均值0.32)相同,这些证据表明岩浆源区主体应为软流圈地幔。Harker图解中元素的相关性分析表明,岩浆可能经历了橄榄石、斜方辉石、单斜辉石和斜长石的分离结晶作用,碳酸盐围岩的混染,二者共同作用导致硫化物熔离成矿。对阿克楚克塞铜镍矿进行了区域、矿区及矿床地质和镁铁-超镁铁岩体特征的总结、硫同位素及S/Se、成矿时代和动力学背景研究,认为阿克楚克塞铜镍矿为中志留世形成的,属于深部熔离-脉冲式贯入型矿床。其有利的构造背景为大洋板片俯冲拉伸,断离,形成板片窗,软流圈物质上涌,经分离结晶,同化混染作用使硫饱和,动力学条件适当的时候,多次上涌形成了阿克楚克塞铜镍矿。
[Abstract]:Qinghai Province, East Kunlun orogenic belt, as of now, has found numerous deposits (spots) in recent years, with the area of magmatic Cu Ni sulfide deposit prospecting breakthrough, the research of this kind of deposits gradually. Chris Alexis Chu copper nickel was found following the summer hamu nickel, another major breakthrough in this type of deposit prospecting which provides important reference for the search area of magmatic Ni Cu sulfide deposits. Chris Alexis copper nickel mine is located in the Chu Kunlun fault in northern Queensland in the basement uplift granite belt. The exposed Proterozoic Jinshuikou group, Cambrian Ordovician Tanjianshan group. There are 2 main faults, near north the F5 and F6. trending fault fracture scale, extending far, 2 construction are transpressional nature. Magmatite in the area are mainly of Neoproterozoic biotite gneiss two, early middle Silurian granite diorite and mafic - ultramafic rocks, Variscan Indosinian Granite porphyry, quartz diorite and granite. Chris Alexis Chu has found 5 areas of basic ultrabasic rocks, which I and II have a lot of work carried out on the rock, sulfide trough and borehole more visible, visible surface of nickel and copper in China, ore grade is higher. 3. IV, V rock for 17 years from now that the construction situation, sulfide more visible, with the mineralization potential well. 1 the rock mass near SN trending tendency E, which showed more tanjianshangroup marble xenoliths. The long axis direction of NNE, irregular shape, the extension is not stable, large variation of grade II rock. The Quaternary overburden is serious, the overall tendency towards NE, SE. II orebody to deep swelling, thickening, grade increased obviously. Almost all of the samples is higher than 0.1%, good continuity, the higher grade area, and the emergence of sideronitic The structure represents the rich ore phenomenon. I, II, the ore rock lithofacies mainly for pyroxenite. Rock and marble for cutting layer. Intrusive mafic ultramafic intrusive complex is a multi period, the sulfide liquation in the deep magma chamber dynamics in certain conditions. Under no ore magma, ore magma, ore magma and ore pulp are pulsed on invasion, formed present disseminated and sideronitic ore. According to the results of electron probe, pyroxene is mainly clinopyroxene class endiopside, En61.64 ~ -65.6, Fs7.74 ~ 10.74, Wo22.96- ~ 26.01, sub alkaline in the series of tholeiitic series, and formed in the arc related environment. I, II is the rock ore body, the two bodies have the similar structure. The main mineral group with pentlandite (Pn) and Ni Hua, chalcopyrite (Cpy) and covellite, pyrrhotite (Po), violarite a small amount of, Limonite, pyrite and Marcasite. Cobalt mineral is unknown, its existing form is mainly in the same phase exists in nickel pyrite; sideronitic ore structure characteristics, exsolution texture, euhedral and subhedral anhedral granular structure and granular structure, inequigranular texture and metasomatic structure; star shaped structure, taxitic structure, crumb structure, disseminated structure, rarely has the massive structure, veinlet. Sulfur isotope and S/Se of rocks and ores show that the range of delta 34S 6.7 per thousand to 11.5 per thousand, from mantle sulfur 0 + 2 per thousand; the ratio of S/Se was 3738~15501, higher than the average value of the mantle. That process of magma from the mantle upwelling, with the addition of crustal sulfur. The Chris pyroxenite of Chu Alexis rock LA-ICP-MS U-Pb dating, determining the crystallization age of 422 + 10Ma, leaving the world for Chi. The ratio of Zr/Nb rock is 16.75 ~ 30.93, and MORB Zr/Nb The ratio (10~60) is close to that of the ratio of Sm/Nd is 0.18 ~ 0.25, with the basic MORB (average 0.32), the evidence suggests that the magma source should be indicated as subject elements related to asthenospheric mantle.Harker graphical analysis of the magma may have experienced olivine, oblique Fang Huishi, fractional crystallization of clinopyroxene and plagioclase the contamination of carbonate rock, the two together lead to segregation of sulfide mineralization. On Alexis copper and nickel were Chris Chu area, mining area and geological and ultramafic rock characteristics summary, sulfur isotope and S/Se, mineralization of the era and the dynamic background, that Chris Chu copper nickel mine in Alexis Silurian formation, belongs to deep liquation pulsed penetration type deposit. The favorable tectonic background for the oceanic plate subduction stretch, break off, forming a slab window, upwelling of the asthenosphere, separated by crystallization, assimilation The effect of sulfur saturation, when appropriate kinetic conditions, many upwelling formed copper nickel. Chris Chu Alexis

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.41;P618.63

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