小兴安岭地区矽卡岩型铁铜（钼）多金属矿床成岩成矿机理与成矿模式研究

发布时间：2018-06-19 18:27

  本文选题：岩浆流体作用 + 成岩成矿机理　； 参考：《吉林大学》2017年博士论文

【摘要】：中国东北部的小兴安岭地区是我国重要的金属矿产产业基地,区内已知Fe、Mo、Au、Cu、Pb、Zn、W、Ag等多种矿产品,均为经济发展与国民生产急需的矿产类型,近年来随着矿产勘查程度的深入,找矿工作不断取得重大突破,已成为中国北方贵金属和有色金属大规模成矿的集中区域。鉴于此,为了揭示制约小兴安岭内生金属成矿的关键基础问题以及成矿规律,本文在前人研究的基础上,针对区内发育的矽卡岩型铁铜(钼)多金属矿床开展系统的矿床地质、流体包裹体、成岩成岩年代学和矿床地球化学等方面的研究,并取得了如下重要成果与进展。1.通过对研究区典型矽卡岩型铁铜(钼)多金属矿床的矿床地质特征研究,进一步得出该类型矿床在下寒武统铅山组碳酸盐岩-碎屑岩建造与侵入岩接触部位的矽卡岩矿化蚀变带内富集成矿,形成以铁、锌、铜、钼为主,其次为钨、铅、金、锡,并伴生镓、铟、镉、银等有益组分的多金属矿体;矿体主要呈透镜状、扁豆状、似层状和脉状等形式产出,而且沿走向或倾向多有膨胀、收缩和分支复合现象出现;常见的围岩蚀变有矽卡岩化、绿帘石化、绿泥石化、硅化、萤石化、绢云母化、碳酸盐化等;成矿阶段可划分为早期矽卡岩阶段、退化蚀变阶段、氧化物阶段、石英-硫化物阶段和碳酸盐阶段,整体符合矽卡岩矿床经典的两期五个成矿阶段的划分模式。2.各典型矿床的流体包裹体研究揭示:(1)早期矽卡岩阶段均发育气液两相包裹体和含子矿物三相包裹体;石英-硫化物阶段主要为气液两相包裹体和含子矿物三相包裹体,其次为少量含CO_2三相包裹体、纯气相以及纯液相包裹体;晚阶段的方解石中仅发育富液相包裹体和纯液相包裹体;(2)宝山矿床中流体包裹体的均一温度从早至晚阶段分别为376.5~512.4℃、291.2~419.5℃、156.3~247.8℃,盐度依次为4.2~49.4%Na Cleqv、1.9~42.2%Na Cleqv、0.7~4.5%Na Cleqv;(3)翠宏山矿床中流体包裹体的均一温度从早至晚阶段分别为332.5~525.5℃、187.3~422.1℃、142.3~235.2℃,盐度依次为14.8~44.1%Na Cleqv、1.4~44.0%Na Cleqv、0.7~6.7%Na Cleqv;(4)二股矿床中流体包裹体的均一温度从早至晚阶段分别为348.9~524.5℃、231.6~380.4℃、152.9~231.6℃,盐度依次为1.9~46.84%Na Cleqv、1.2~37.4%Na Cleqv、1.4~4.5%Na Cleqv;(5)激光拉曼分析结果显示,早期矽卡岩阶段的石榴子石、透辉石和绿帘石中的包裹体的气相成分均为H_2O,未见其它成分;石英硫化物阶段的石英中包裹体的气相成分为CO_2或CO_2+CH_4,指示流体具有较强还原性;晚阶段方解石中包裹体的成分主要为H_2O;(6)氢-氧同位素结果显示,区内矽卡岩型铁铜(钼)多金属矿床的初始成矿流体可能为残余岩浆水,随着成矿作用的进行大气降水混入的比例逐渐增加,到成矿晚阶段主要为大气降水流体。综合显微测温、拉曼成分分析和氢氧同位素结果,进一步揭示研究区矽卡岩型铁铜(钼)多金属成矿系统的初始含矿流体来源于残余岩浆出溶的高温、高盐度、高氧逸度的H_2O-Na Cl-CO_2±CH_4体系,流体演化过程中不断有大气降水加入;并且成矿过程中岩浆熔-流分离作用和水-岩作用使成矿物质富集,而流体沸腾和混合作用是导致成矿物质最终沉淀的成矿机制。3.研究区内矽卡岩型铁铜(钼)多金属矿床的成岩成矿年代学研究表明:(1)首次限定宝山铜多金属矿床的成矿时代在245~255Ma之间,即晚二叠世-早三叠世,矽卡岩型矿化与角闪石英二长岩关系密切;(2)翠宏山矿区内至少存在三期岩浆活动,其中第二期早侏罗世二长花岗岩岩浆作用与成矿关系最为密切,矿床形成于198~204Ma,即晚三叠世晚期-早侏罗世早期;(3)二股西山和东山矿段的成矿作用发生在180~184Ma之间,成矿与黑云母二长花岗岩岩浆活动密切相关;响水河矿段的成矿时限为191~194Ma,较前者成矿早约10Ma。结合本文及前人的研究成果,我们认为研究区内矽卡岩型铁铜(钼)多金属矿床的有两个成矿期,分别为晚二叠世-早三叠世(245~255Ma;以宝山矿床为代表)和晚三叠世-早侏罗世(180~205Ma),后者还可划分为198~205Ma(以翠宏山、大西林、前进东山矿床为代表)、191~193Ma(以响水河、大安河矿床为代表)和180~184Ma(以二股西山、二股东山、徐老九沟矿床为代表)三个成矿阶段。4.在矽卡岩矿物学方面,研究区内典型矽卡岩型铁铜(钼)多金属矿床的石榴子石和辉石组成与世界上对应矿种的矽卡岩型矿床的石榴子石和辉石的分布区间基本一致,其中宝山和二股矿床中的石榴子石主要为钙铁榴石,其次为钙铝榴石,翠宏山矿床仅发育钙铁榴石;三个矿床中辉石均以透辉石为主,仅翠宏山矿床中出现少量钙铁辉石;这些特征均指示早期矽卡岩阶段整体处于酸性、高温、高氧逸度的环境,高氧逸度促使Fe3+进入到石榴子石和辉石中形成钙铁榴石和透辉石,并且有向弱还原性环境演化的趋势,从而形成少量的钙铝榴石和钙铁辉石。5.与成矿密切相关的侵入岩岩相学和元素地球化学研究揭示,宝山矿床的成矿岩体为一套准铝质高钾钙碱性的角闪石英二长岩-似斑状黑云母花岗岩组合;翠宏山矿床成矿与准铝质高钾钙碱性的二长花岗岩有关,还发育有成矿前的碱长花岗岩以及成矿后的花岗斑岩;二股矿床成矿岩体为准铝质、钾玄岩-高钾钙碱性黑云母二长花岗岩。三个矿床与成矿相关的侵入岩多具有高硅、富铝和富碱,稀土元素含量较高,轻重稀土之间分异明显,富集LREE、Th、U及大离子亲石元素Rb、K,亏损HREE、Ba及高场强元素Nb、Ta、P、Ti等,与翠宏山和二股矿床的成矿岩体显示明显的Eu负异常不同,宝山矿床与成矿有关侵入岩发育弱的Eu负异常。6.与成矿密切相关的侵入岩的Sr-Nd和Lu-Hf同位素研究表明,宝山矿床与成矿相关的角闪石英二长岩起源于中元古代增生的下地壳物质;翠宏山矿床的岩浆属性有两种,碱长花岗岩的岩浆起源于古老的陆壳基底的部分熔融,二长花岗岩的岩浆起源于新-中元古代新生下地壳或岩石圈地幔,并受到少量古老陆壳物质混染;二股矿床成矿岩体黑云母二长花岗岩与翠宏山二长花岗岩具有相似的Sr-Nd和Lu-Hf同位素,其岩浆起源于新-中元古代增生的下地壳物质或岩石圈地幔,并可能有少量古老地壳组分加入。7.将流体演化、岩浆作用与区域构造演化背景相结合,揭示研究区矽卡岩型铁铜(钼)多金属矿床的成岩成矿地质过程:(1)晚二叠世-早三叠世,随着古亚洲洋的最终闭合,华北板块与松嫩地块持续的陆-陆碰撞作用导致下地壳加厚并发生拆沉作用,进入到下伏地幔中并发生部分熔融形成埃达克质岩浆,并且岩浆在上升过程中与地幔橄榄岩发生了强烈的交代作用,从而使铜等成矿元素在岩浆系统中富集,随着埃达克质岩浆上升到地壳浅部就位,从埃达克质岩浆中出溶形成富铜的成矿流体,在与碳酸盐岩地层的接触带内形成大范围的矽卡岩化以及相关的矿化,最终形成的宝山矽卡岩型铜多金属矿床;(2)晚三叠世-早侏罗世早期,适值西伯利亚板块与华北板块碰撞造山后的伸展构造环境,区域性的岩石圈伸展造成大规模软流圈物质上涌致使新生玄武质加厚下地壳发生部分熔融,形成初始的含矿岩浆,并且在上侵过程中受到少量的古老地壳混染,随着岩浆上升到地壳浅部就位,岩浆熔体演化晚期分离出大量含挥发分和Fe、Mo、W等成矿元素的流体,在构造应力和岩浆热的驱使下,含矿流体发生侧向逃逸并与周围碳酸盐岩地层发生交代反应,最终形成的翠宏山矽卡岩型铁多金属矿床;(3)早侏罗世晚期,太平洋板块向欧亚大陆的俯冲过程中板片脱水释放的流体交代早期元古代次生岩石圈地幔发生部分熔融形成玄武质岩浆,并与地幔橄榄岩发生了强烈的交代作用,从而使Fe、Cu等成矿元素在岩浆系统中富集,随后玄武质岩浆底侵下部地壳,促使下地壳岩石发生部分熔融形成花岗质岩浆并与玄武质岩浆发生混合,这一壳幔混合岩浆在上升演化过程中受到少量的地壳混染,最终在近地表冷凝成岩,并与附近的碳酸盐地层发生大规模的接触交代作用,导致Fe、Zn、Cu等成矿元素发生大规模沉淀形成二股矽卡岩型铁多金属矿床。
[Abstract]:The small Xingan ridge area in northeastern China is an important metal mineral industry base in China. It is known that Fe, Mo, Au, Cu, Pb, Zn, W, Ag and other mineral products are all the mineral types which are urgently needed for economic development and national production. In recent years, with the depth of mineral exploration, the prospecting work has made great breakthroughs and has become the precious metal in the north of China. In view of this, in order to reveal the key basic problems and metallogenic regularities of the inner metallization of the small Xingan ridge, this paper, based on the previous studies, carried out a systematic deposit geology, fluid inclusions and formation rock age on the basis of previous studies. Studies on the geology and geochemistry of ore deposits have made the following important achievements and progress.1. through the study of the geological characteristics of the typical skarn type copper (molybdenum) polymetallic deposit in the study area, and further concluded that this type of ore deposit is in the carbonatite mineralization of the lower Cambrian carbonate rock debris rock formation and intrusive rocks. A polymetallic ore formed in the altered zone, formed mainly of iron, zinc, copper, molybdenum, followed by beneficial components such as tungsten, lead, gold, tin, and associated with gallium, indium, cadmium, silver and other useful components; the orebodies are mainly lenslike, lentil like, like lamellar and pulse forms, and appear more expansive, contractile and branching complex phenomena along the direction or tendency; common surrounding rock erosion. There are skarn, epidote, chlorinization, silicification, fluorofossilization, sericification, carbonation, and so on. The metallogenic stage can be divided into early skarn stage, degenerated alteration stage, oxide stage, quartz sulfide stage and carbonate stage, which are in accordance with the classic five stages of the skarn deposit. Fluid inclusion studies of type deposits reveal: (1) both gas-liquid inclusions and three phase inclusions are developed in the early skarn phase, and the phase of quartz sulfide is mainly gas-liquid and subphase inclusions containing subaqueous minerals, followed by a small amount of CO_2 inclusions, pure gas and pure liquid inclusions, and the late phase solution. The rich liquid inclusions and pure liquid inclusions are developed only in the stone. (2) the homogeneous temperature of fluid inclusions in the Baoshan deposit is from early to late stage at 376.5~512.4, 291.2~419.5 and 156.3~247.8, respectively, and the salinity is 4.2~49.4%Na Cleqv, 1.9~42.2%Na Cleqv, 0.7~4.5%Na Cleqv, and (3) the homogeneous temperature of fluid inclusions in the Cui Hong mountain deposit The early and late stages are 332.5~525.5 C, 187.3~422.1 C, 142.3~235.2 C, and the salinity is 14.8~44.1%Na Cleqv, 1.4~44.0%Na Cleqv, 0.7~6.7%Na Cleqv. (4) the homogeneous temperature of fluid inclusions in the two strand deposits is 348.9~524.5 C, 231.6~ 380.4 C, 152.9~231.6, and salinity, respectively. 4%Na Cleqv, 1.4~4.5%Na Cleqv; (5) the results of laser Raman analysis show that the gas phase composition of the inclusions in the diopside and epidote of the early skarn phase is H_2O, and no other components are found. The gas phase composition of the inclusions in the quartz sulfide phase is CO_2 or CO_2+CH_4, indicating that the fluid has a strong reducibility and late order. The composition of the inclusions in the calcite is mainly H_2O; (6) the results of hydrogen oxygen isotope show that the initial ore-forming fluid of the skarn type iron copper (molybdenum) polymetallic deposit in the region may be residual magma water, and the proportion of the mixing of meteoric water gradually increases with the mineralization, and it is mainly atmospheric precipitation fluid at the late stage of mineralization. The results of temperature, Raman composition analysis and hydrogen and oxygen isotopes further reveal that the initial ore bearing fluid of the skarn type iron copper (molybdenum) metallogenic system in the study area is derived from the high temperature, high salinity, high oxygen fugacity H_2O-Na Cl-CO_2 + CH_4 system of the residual magma, and the continuous atmospheric precipitation in the process of fluid evolution; and the rocks in the process of mineralization. The Cheng Yan metallogenic chronology of the skarn copper (molybdenum) polymetallic deposit in the.3. study area of the study area of the skarn type copper (molybdenum) polymetallic deposit in the study area of the study area in the study area of the skarn type iron copper (molybdenum) deposit in the study area of the metallogenic mechanism for the final precipitation of the ore-forming process in the study area of the ore-forming mechanism.3. in the study area of the ore-forming mechanism in the study area of the skarn type and copper (molybdenum) polymetallic deposit in the area of (1) the first limitation of the metallogenic epoch of the copper polymetallic deposit in the 245~255Ma. In the Late Permian early three fold, the skarn mineralization is closely related to the hornblende quartz two long rocks; (2) there are at least three stages of magmatic activity in the Cui Hongshan mining area, of which the second phase of the early Jurassic two feldspar magmatism is most closely related to the mineralization, and the deposit formed in 198~ 204Ma, that is, late late three early Jurassic and (3) two strands. The mineralization of the Xishan and Dongshan mines occurs between 180~184Ma, and mineralization is closely related to the magmatic activity of the biotite two granitic magma, and the metallogenic time limit of the Xiang Shui River section is 191~194Ma, which is earlier than the former 10Ma. combined with the previous research results, and we think that there are two of the skarn type copper (molybdenum) polymetallic deposits in the study area. The metallogenic period is the Late Permian early three fold (245~255Ma; the Baoshan deposit as the representative) and the late three fold early Jurassic (180~205Ma), and the latter can also be divided into 198~205Ma (the cuihongshan, Daxilin, the forward Dongshan ore deposit), 191~193Ma (represented by the Hongshui River, the Da'an River deposit) and 180~184Ma (with the two strands of Xishan, two shares Dongshan, Xu Lao " The nine gully deposit is the representative) the three metallogenic stage.4. in the skarn mineralogy, the garnet and pyroxene composition of the typical skarn type iron copper (molybdenum) polymetallic deposit in the study area is basically the same as the garnet and pyroxene in the skarn type ore deposits in the world, including the garnet in Baoshan and two strands. It is mainly calcite, followed by calcite. The Cui Hong mountain deposit only develops calcite. The three deposits are mainly diopside, only a small amount of calcite pyroxene occurs in the Cui Hong mountain deposit. These characteristics indicate that the early skarn stage was in the environment of acid, high temperature, high oxygen fugacity, and high oxygen fugacity promoted Fe3+ into the pomegranate. The formation of calcite and Diopside in the zigzite and pyroxene, and the trend towards the evolution of the weak reductive environment, forms a small amount of calcite and calcite.5., which is closely related to the metallogenic and elemental geochemistry of the mineralization. The ore-forming body of the Baoshan deposit is a set of paralic, high potassium calc alkaline quartz. Two long rocks like porphyritic biotite granites, the cuihongshan ore deposit is related to the paralic high potassium calc alkaline two feldspar granite, the alkali feldspar granite before the mineralization and the granite porphyry after the mineralization; the two ore deposits are paralic, potassium basalite and high potassium calcicine biotite two granitic granite. Three ore deposits and metallogenic facies. The intrusive rocks are high in silicon, rich in aluminum and rich in alkali, with high rare-earth elements and obvious differentiation between heavy and heavy rare earth elements, enriched with LREE, Th, U and large ion stone elements Rb, K, HREE, Ba and high field strength elements Nb, Ta, P, Ti, etc., which are different from that of the Cui Hong and two ore deposits. The Sr-Nd and Lu-Hf isotopes of the intrusive rocks closely related to the mineralization of the weakly intrusive Eu indicate that the Baoshan deposit and the ore-forming hornblende quartzite two long rocks originate from the Mesoproterozoic lower crust material, and the magma property of the Cui Hong mountain deposit is two, and the magma of the alkali long flower granitic rocks originates from the ancient continental crust basement. The magma of the two granites originates from the Neozoic Mesoproterozoic Neozoic lower crust or lithosphere mantle, and is contaminated by a small amount of ancient continental crust material, and the two strands of the black mica two granite and the Cui Hongshan two granites have similar Sr-Nd and Lu-Hf isotopes, and their magma originated from the new Mesoproterozoic accretion. The crust material or lithosphere mantle, and may have a small amount of ancient crustal components joining.7. to combine the fluid evolution, magmatism and regional tectonic evolution background, reveals the diagenesis and metallogenic geological process of the skarn type iron copper (molybdenum) polymetallic deposit in the study area: (1) the Late Permian early three fold, with the final closure of the ancient Asian Ocean, the North China plate and the North China plate The continuous continental collision in the Songnen block resulted in the thickening and delamination of the lower crust, which entered the lower mantle and formed part of the partial melting to form the enactic magma, and the magma had a strong metasomatism with the mantle peridotite during the rising process, thus enriching the copper and other metallogenic elements in the magma system. The qualitative magma ascended to the shallow part of the crust and formed a rich copper rich metallogenic fluid from the ark magma, forming a wide range of skarite and related mineralization in the contact zone with the carbonate strata, and finally formed the Baoshan skarn copper polymetallic deposit; (2) the late three fold early Jurassic period and the appropriate value of the Siberia plate. In the extensional tectonic environment after the collision of the North China plate, the regional lithosphere extension causes the mass of the massive asthenosphere to cause the partial melting of the new basaltic thickening lower crust and the formation of the initial ore bearing magma, and in the process of invasion, a small amount of ancient crust is mixed, and as the magma ascends to the shallow part of the crust, the rock is in place. In the late evolution of the pulp melts, a large number of fluids containing volatile components and Fe, Mo, W and other metallogenic elements were separated from the tectonic stress and magmatic heat, and the ore fluid occurred laterally and formed a metasomatism with the surrounding carbonate rocks, and finally formed the cuihongshan skarn type iron polymetallic deposit; (3) the late Early Jurassic, the Pacific plate direction. During the subduction of the Eurasian continent, the early metasomatism of the Proterozoic secondary lithospheric mantle was partially fused to form basaltic magma, which had a strong metasomatism with the mantle peridotite, thus enriching the Fe, Cu and other metallogenic elements in the magma system, and then the basaltic magma undertook the lower crust, prompting the lower earth. The partial melting of the crust rock formed granitic magma and mixed with the basaltic magma. This crust mantle mixed magma was contaminated by a small amount of crust during the process of rising and evolution, and finally condensed into rock in the near earth surface, and had a large contact metasomatism with the adjacent carbonate strata, leading to the large regulation of Fe, Zn, Cu and other metallogenic elements. Die formed two skarn iron polymetallic deposit.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.2
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本文编号：2040851