金川铜镍硫化物岩浆矿床前锋岩浆与岩浆通道

金川铜镍矿床是世界第三大镍、铜硫化物岩浆矿床,长期以来备受国内外矿床地质学家的关注.金川铜镍矿床Ⅳ矿区是金川矿床的有机组成部分,由于品位低(Ni 0.71％、Cu 0.48％)并且隐伏于地下140 m以下,生产与研究工作相对滞后.由于F23断裂构造的影响,金川矿床勘查以来,研究者均将其作为Ⅱ矿区2#岩体的东延部分.最近的详查钻探工程获得了较系统的样品测试,结果显示Ⅳ矿区含矿岩体是一个具有单独演化过程的独立含矿岩体,其Ni/Cu比值远高于其他矿区各个岩体,PGE强烈亏损,并且“R”因子数值低(30),微量、稀土元素配分也显示出独立的、复杂的演化过程,岩石结构与岩相变化显著,具有典型的岩浆通道前锋岩浆的特点.文章通过对比金川矿床几个主要含矿岩体的成矿元素与PGE特征,初步确定了金川铜镍硫化物成矿岩浆通道的空间位置,指出了金川深部资源勘查的关键问题与勘查方向.     

吉林长仁铜镍矿床地质特征及矿床成因探讨

长仁铜镍矿床产出在∑11号岩体中,而岩体赋存于长仁-青龙断裂的NNE向压扭性构造带内,围岩为奥陶系青龙村群下段地层( Oq1-3).岩体呈岩株状、透镜状,岩体与围岩接触面呈舒缓波状.矿体赋存在∑11号超薄性岩体的辉石橄榄岩-含长辉石橄榄岩岩相中,呈似层状、透镜状产出.该矿床的成因初步认为是岩浆晚期熔离-贯入型矿床.     

金川铜镍矿床的地球物理深部结构与成因模式

在甘肃省金川矿区利用磁法、可控源音频大地电磁法及地震P波层析方法进行了深部探测,几种方法综合研究确定了到达2 500 m以上高阻高速体的岩浆源特征,指出了岩浆上涌到达浅部向两侧扩展的近水平的透镜状分支,作为可能的深部含矿超基性岩体与钻孔已见矿体位置相吻合,为金川铜镍矿床的成因模式提供了地球物理依据。建议在进一步研究中应重视探测产状平缓、近水平的高速、低阻体。     

Geology and geochemistry of natural gases in Talnakh deposit of copper-nickel ores

Thermal and, to a lesser degree, regional metamorphism are responsible for generation of the gases, mainly from coals and carbonaceous rocks of the Tunguska Series, the bulk of which is in the adsorbed state and also in solution, in subsurface waters. Heavy hydrocarbons and hydrogen content of the gaseous mixture exceed the threshold of safety; the mixture is explosive at relatively low temperatures. – V. P. Sokoloff.     

桂北宝坛地区铜镍硫化物矿床成矿模式

桂北宝坛地区发育中元古代基性超基性岩体,分为第一期（Ⅰ）的层状、似层状基性-超基性杂岩体和第二期（Ⅱ）的岩盆状中基性杂岩体。第二期岩浆活动为多中心式侵入,具有良好的深部岩浆熔离分异作用和铜镍成矿的地质条件。同位素年代学揭示,铜镍硫化物成矿为两期成矿,建立了两期多阶段的成矿模式,研究指出,在岩浆穹窿构造底部及下伏岩浆侵入通道及附近的断裂构造是主要的成矿场所。     

新疆喀拉通克铜镍矿地震资料噪声分析与压制

金属矿地震勘探中原始数据的信噪比较低,多种干扰波混杂在地震记录中,严重影响了金属矿地震资料的成像质量。因此,选择有效的去噪方法是提高资料品质的关键。以新疆喀拉通克铜镍金属矿区地震资料处理为基础,在FOCUS5.4处理软件平台下采用多方法联合去噪技术压制单频波、声波、面波以及机械振动等干扰。通过模块测试和参数调试,找到适合该金属矿区的去噪方法技术。经过去噪处理,大幅提高了金属矿地震资料的信噪比。     

金川铜镍矿床成矿后的抬升破坏:来自热年代学的证据

以热年代学原理为指导,在以往成岩成矿年龄的基础上,结合矿区内裂变径迹测试结果,认为金川矿床经历了初期的急速抬升冷却、中期(827 Ma±766 Ma±乃至403 Ma)、晚期(308 Ma)和中、新生代的快速折返冷却过程,也遭受了1 508~827 Ma、403~308 Ma两次增温改造事件;而同一样品中相似的磷灰石和锆石裂变径迹年龄表明金川矿区至少在晚白垩纪早期经历了极速的抬升冷却、剥蚀事件。F8断裂西侧的抬升明显慢于其东侧,体现出矿区内抬升速率的差异性,这对找矿预测具有借鉴意义。     

金川铜镍硫化物矿床的Re-Os"年龄"及其意义

分析了金川铜镍硫化物矿床的一组浸染状矿石和一组块状矿石的Re、Os含量和Os同位素组成.浸染状矿石和块状矿石分别给出Re-Os表观等时线年龄为(1 126±96)Ma和(840±79)Ma,表观初始187Os/188Os比值为0.119±0.018和0.242±0.028.块状矿石的表观年龄与前人报道的同类矿石年龄在误差范围内一致,证明了其分析的可靠性.此结果也与前人报道的锆石和斜锆石的U-Pb年龄在误差范围内一致,说明了金川的新元古代成矿时代.而我们的和前人的工作表明,海绵陨铁状矿石和浸染状矿石给出的Re-Os表观年龄有相当大的变化范围,且都比块状矿石的年龄老.提出了两种模式解释这种现象:在约8亿年前金川矿床形成时地壳混染导致浸染状矿石和海绵陨铁状矿石的Os同位素组成不均一,从而给出偏老的表观年龄;相反,Os同位素在块状矿石中快速扩散而均一化,因此给出成岩成矿年龄.但是,还不能完全排除两期成岩成矿的可能性,即晚期岩浆活动引起了早期岩浆活动中封闭的Re-Os同位素体系的扰动.目前倾向于第一种解释,但后一种可能性还需要检验.     

Geological structures of the Norilsk copper-nickel deposit: A new interpretation of the seismic refraction data

Regional seismic works in the area of the Norilsk copper-nickel deposit were made using the seismic refraction method in the 1980s. These data were used to derive new information about the studied area. The data of eight profiles of about 2900 km total length were processed by the homogeneous functions method and reinterpreted. Based on the seismic sections thus derived, horizontal slices were built to identify the spatial positions of structures and produce the volume image of the basement??s ledge. Seismic sections of 10?C20 km in depth and horizontal slices contain the information about the boundaries, reflect the volume internal structure of sedimentary strata and basement, and show the faults.     

Geology, mineralogy, and PGE mineralization of the copper-nickel occurrences of the Kvinum ore field, Sredinny Range, Kamchatka

The geology and mineralogy of host metamorphic rocks, the mineralogy of sulfide ores, and the distribution of PGE mineralization were studied in detail for the Kvinum-1 and Kvinum-2 copper-nickel occurrences of the Kvinum ore field, which are the most promising targets for the copper-nickel-PGE mineralization of the Sredinny Range of Kamchatka. It was established that stringer-disseminated and massive copper-nickel ores are localized in amphibole peridotites, cortlandites, and form ore bodies varying from tens of centimeters to 5–20 m thick among the layered cortlandite-gabbroid massifs. The massive sulfide ores were found only at the bottom of cortlandite bodies and upsection grade into stringer-disseminated and disseminated ores. Pyrrhotite, chalcopyrite, and pentlandite are the major ore minerals with a sharply subordinate amount of pyrite, sphalerite, galena, arsenopyrite, and löllingite. Besides pentlandite, the Ni-bearing minerals include sulforasenides (gersdorffite), arsenides (nickeline), and tellurides (melonite) of nickel. It was found that PGE mineralization represented by antimonides (sudburyite) and tellurobismuthides (michenerite) of Pd with sharply subordinate platinum arsenide (sperrylite) is confined to the apical parts of massive sulfide zones and the transition zone to the stringer-disseminated ores. Ore intervals enriched in arsenides and tellurides of Ni, Pd, and Bi contain high-purity gold. In the central parts of the orebodies, the contents of PGE and native gold are insignificant. It is suggested that the contents of major sulfide minerals and the productivity of PGE mineralization in the cortlandites are defined by combined differentiation and sulfurization of ultramafic derivatives under the effect of fluids, which are accumulated at the crystallization front and cause layering of parental magmas with different sulfur contents. The fluid-assisted layering of mafic-ultramafic massifs resulted in the contrasting distribution of PGM in response to uneven distribution of sulfur (as well as As, Te, and Bi) during liquid immiscibility. The productivity of PGE mineralization significantly increases with increasing contents of S, As, Te, and Bi (elements to which Pt and, especially, Pd have high affinity) in fluids.     

Yurchik Massifs in Kamchatka: Age and affiliation to magmatic associations

Petrographic and isotopic-geochemical data obtained on basic and ultrabasic rocks from the Yurchik Massif in the Ganal block of crystalline rocks in Kamchatka indicate that the distribution of major and trace elements in these rocks are analogous to those in the fractionation products of high-Al tholeiites occurring in island arcs in the eastern continental margin of Eurasia. Allivalites and dunites found as nodules in gabbronorites and gabbro of the massif are thought to be early cumulates of arc basalts. Petrographic and geochemical characteristics of the Yurchik Massif make it different from Ni-bearing Paleocene-Eocene (approximately 50 Ma) norite-cortlandite intrusions in the Sredinnyi Range of Kamchatka. U-Pb zircon and ⁴⁰Ar/³⁹Ar dates for rocks from the massif definitely testify to its younger, Early Miocene (approximately 22 Ma) age.     

The Asachinskoe epithermal Au-Ag deposit in southern Kamchatka: physicochemical conditions of formation

The Asachinskoe epithermal Au-Ag deposit (southern Kamchatka) is referred to as low-sulfidation in quartz-adularia-sericite in Corbett's classification. Research into fluid inclusions of its minerals gave an insight into the PT-conditions of formation and gas composition of ore-forming fluids as well as the vertical variations in these parameters to a depth of more than 200 m within a 2 km long horizontal site of the deposit ore zone. It is shown that mineral assemblages formed at 320 to <100 °C. Ore-forming hydrothermal solutions were poor in salts (3–9.2 wt.% NaCl equiv.), with NaCl being the main component. Mineral assemblages with high contents of Au crystallized at 250–175 °C. Ore-free quartz-carbonate veins formed at 80–120 °C. High-temperature (300–320 °C) veins also lack ores. Rich gold ores were deposited in the environments where ore-bearing fluids boiled, mixing with meteoric waters.     

俄罗斯堪察加中部Baranevskoy金-银矿床矿物学与流体包裹体研究

Baranevskoy金-银矿床产于巴尔喀什火山的火山口,该火山坐落在堪察加中部矿区东南部。本文基于矿物学原理和流体包裹体数据分析探讨了Baranevskoy金-银矿床的成矿环境及其物理化学条件。Baranevskoy金-银矿床的围岩为中新世—上新世的安山岩和玄武岩。热液蚀变活动随深度逐渐变化,从而可以进一步划分出最深部的石英带、中部的石英-绢云母(明矾石)-黄铁矿-铁钛氧化物带及其伴生的石英-绢云母-伊利石-黄铁矿矿物组合和浅部的石英-冰长石-水云母-黏土矿物-碳酸盐岩带。成矿早期存在密集浸染的铜矿化,主要矿石矿物有黄铜矿、斑铜矿、砷黝铜矿-黝铜矿,并在Rhzavaya矿脉中存在少量的自然金。其中砷黝铜矿-黝铜矿系列以砷黝铜矿和黝铜矿两个端员作为代表,且以黝铜矿为主。成矿后期产出代表晚期金-银矿化的自然金、黄铁矿、黄铜矿、闪锌矿、方铅矿、碲化物和硫酸盐等标志性矿物。早期铜矿化(第一期)被认为是中硫阶段,紧随其后的为低硫型金-银矿化(第二期和第三期)。金从第一期到第三期都有沉淀。经研究发现,自然金也赋存于变质围岩的岩石裂隙内。早期的自然金相对富银,其中金的摩尔分数为59%~65%,低于后期(第二、第三期)自然金中金的摩尔分数(64%~72%)。流体包裹体显微测温结果显示,位于中部(Central)矿脉的包裹体均一温度为190~280 ℃,Rzhavaya矿脉的包裹体为190~240 ℃,产出自然金的蚀变围岩中石英的包裹体温度为230~310 ℃。包裹体总体表现出低盐度(0.9%~2.4% NaCl_eq)特征,推测存在大气水的混入。     

中国新生代上地幔铅同位素地球化学场对成岩、成矿物质来源的制约——以斑岩铜矿床及铜镍硫化物矿床为例

区域成矿带铅稳定同位素地球化学研究是区域地球化学分区、示踪成岩成矿物质来源、阐明矿床成因的有效途径。本文以中国特有的大地构造背景为基础,以新生代上地幔铅同位素组成的地球化学场为依据,示踪了中国大型、超大型斑岩型铜矿床及铜镍硫化物型矿床的成岩成矿物质来源。结果显示:①斑岩型铜矿床及铜镍硫化物型矿床成矿母岩继承了所属陆块的上地幔铅同位素组成特征;②两类矿床的含矿岩体和矿石矿物铅同位素组成十分一致,示踪两者同源;壳熔花岗岩和围岩地层的铅同位素组成与矿石铅同位素组成迥异;③位于各陆块的斑岩型铜矿床及铜镍硫化物型矿床的成矿母岩和矿石铅同位素组成除继承了各陆块上地幔不同的铅同位素组成特征外,还示踪了壳幔层圈间耦合性的"块体效应",同时,上地幔铅同位素组成可能还具"延迟效应"。     

吉林红旗岭铜镍矿床地电化学异常特征、成晕机制及找矿预测

通过在吉林红旗岭铜、镍矿区开展研究,在铜、镍矿体上同步垂直出现了Cu、Ni、Co、Pt、Cr、Sr异常.异常值的高低排列顺序是Cu＞Ni＞Co＞＞Pt＞Cr＞Sr,呈明显的电化学异常标志.对铜、镍矿的电化学溶解试验研究的结果表明,当铜、镍矿标本电解到24 h,其溶液中的Cu2 、Ni2 、Co2 离子质量分数分别达到2.2×10-6、1.8×10-6、1.5×10-6,充分证明铜镍矿床不但能产生电化学溶解,而且电化学溶解能力较强.经过在吉林红旗岭矿区深部找矿预测,发现3处具有成矿远景的地电化学异常,表明该方法具有良好的找矿效果.     

Age of Ichinsky and Khangar Stratovolcanoes (Sredinny Range,Kamchatka)

Doklady Earth Sciences - The K–Ar isotopic age of the beginning of formation of Ichinsky (0.35) and Khangar (0.4) stratovolcanoes is established for the first time, as well as the age of the...     

Age of supraore sequence at the syrostan talcomagnesite deposit in the southern Urals

The first information on findings of fossils in the supraore sequence in the open pit at the Syrostan talcomagnesite deposit in the southern Urals is reported. The remains of colonial corals (Tabulata) indicate the Visean age of the coaly-carbonate sequence that overlies talcomagnesite.     

滇西北普朗斑岩铜矿床成矿时代及其意义

普朗斑岩铜矿在中国斑岩铜矿床中有其特殊性,无论对中甸岛弧带的基础地质还是矿产资源评价预测的研究,都具有重要意义。然而,该斑岩铜矿床无确切的年代学数据。通过作辉钼矿Re-Os年龄和单矿物K-Ar年龄测定,首次确定了普朗斑岩铜矿床内具有钾硅酸盐化的黑云石英二长斑岩成矿作用的活动时间为(235.4±2.4)Ma～(221.5±2.0)Ma,石英-辉钼矿阶段的辉钼矿Re-Os年龄大致为(213±3.8)Ma,两者十分相近。表明普朗斑岩铜矿床的成矿作用是在印支期完成的。主矿体钾长石K-Ar年龄显示热液活动持续到(182.5±1.8)Ma左右,说明与斑岩铜矿有关的热液系统寿命可达40Ma之久。这种长寿命的热液系统是高品位大规模的斑岩铜矿形成的必要条件之一。