松辽盆地西南部上白垩统姚家组原生黏土矿物组合特征及其找铀意义

黏土矿物是砂岩型铀矿表生成矿流体水-岩作用的重要产物。本文以岩心光谱扫描为主要技术手段,结合野外地质编录、偏光显微镜、扫描电镜等方法,首次对松辽盆地西南部钱家店铀矿床及远离矿区的88个钻孔超过9 000 m岩心进行了系统的蚀变矿物填图,提取了主要黏土矿物和Fe~(3+)氧化物信息。结果表明,主要产铀层位姚家组原生黏土矿物组合主要是"伊利石+(蒙脱石)伊蒙混层",仅有少量的高岭石、绿泥石,它们与松辽盆地北部具有相似特征,是沉积期古气候的响应。而成矿段中,高岭石含量与铀矿物具有明显正相关性,是成矿流体轨迹的重要指标。原生砂岩的黏土矿物、Fe~(3+)氧化物矿物(化)信息往往呈现成层性或韵律式变化,而经过成矿流体改造的砂岩,其黏土矿物、Fe~(3+)氧化物信息往往呈现"舌状"或"正态曲线状"的突然变化,这些特征可以成为原生砂岩颜色判别和后生成矿流体追踪的重要指标,它们对砂岩型铀矿成矿规律研究与找矿具有重要意义。     

川西甲基卡锂矿基地典型岩石及矿物反射波谱特征研究

四川甲基卡矿田是中国乃至于世界上锂矿资源最集中的地区之一,目前对甲基卡锂矿床的光谱学认识还很欠缺。本文运用地物波谱仪对甲基卡地区野外采集的典型岩石及矿物开展波谱测试,建立了研究区样品的波谱数据库,总结了黑云母片岩、十字石片岩、十字石堇青石片岩、角岩、二云母花岗岩、含锂辉石伟晶岩、不含锂辉石伟晶岩、石英脉、长石斑晶、锂辉石、云母、绿柱石的波谱特征。研究结果表明:围岩与岩体波谱特征差异较大,围岩反射率一般在0. 2以下,吸收特征不明显,岩体反射率一般在0. 5以下,具有1413 nm、1911 nm、2197 nm三处不同程度的吸收特征;其中含矿伟晶岩、不含矿伟晶岩及花岗岩可以通过1413 nm及2197 nm等处的吸收特征进行区分;锂辉石及绿柱石具有独特的波谱特征,可以直接用于找矿。本文开展的甲基卡型锂矿地面波谱研究,对其高光谱遥感填图及地质找矿具有重要的指导意义。     

云南斑岩型多金属金矿的嵌布特征及赋存状态研究

云南西部有大量低品位金矿资源,且具有嵌布粒度不均匀、矿石结构复杂、解离不完全等特点,传统工艺矿物学分析不易快速、准确测定金赋存状态及载金矿物的嵌布特征。本文利用矿物自动分析系统(MLA)、化学分析等方法对滇西多金属金矿进行系统的工艺矿物学研究,查明了该矿的矿物组成、嵌布粒度、连生及包裹关系,同时阐明了载金矿物的工艺矿物学性质对金回收率的影响。结果表明:金主要以游离态自然金的形式存在,嵌布粒度极细,主要集中在0.01~0.02 mm粒度级别;小于0.074 mm粒级的金占原矿总金量的50.08%,其余金以微细包裹体分散于黄铁矿、磁铁矿、黄铜矿等载金矿物中。但载金矿物粒度较细,解离性差,嵌布不均匀,因此提高载金矿物解离度是提高金回收率的一个重要参考方向。     

西藏多龙矿集区铁格隆南超大型Cu(Au、Ag)矿床硫锡砷铜矿研究及其地质意义

铁格隆南矿床位于班公湖-怒江成矿带西段多龙矿集区,是青藏高原发现的首例具有典型高硫型浅成低温热液矿化特征的超大型Cu(Au、Ag)矿床。笔者通过对该矿床进行系统的矿相学研究,结合电子探针显微分析,首次在该矿床发现了硫锡砷铜矿,虽然其总量不多,但其与不同矿物组合特征可反演其形成时的物化条件,对矿床成因类型判别具有一定指示意义。该矿床中的硫锡砷铜矿多为粒径约10μm的不规则细粒,无内反射,均质性,与硫砷铜矿、砷黝铜矿等Cu-As-S体系矿物伴生产出时呈乳黄色-淡黄色,与斑铜矿、黄铁矿、蓝辉铜矿等CuFe-S体系矿物伴生产出时呈乳褐色-浅褐色。根据矿物之间的交代关系发现,硫锡砷铜矿形成于黄铁矿、斑铜矿、砷黝铜矿、硫砷铜矿之后,蓝辉铜矿、铜蓝之前。电子探针分析显示,硫锡砷铜矿的基本成分包括Cu、As、V、S、Sn、Sb,普遍含有少量Fe、Ge、Zn,部分样品中含少量W、Au、Ag,以S原子数为32为基础,计算得出其分子式为Cu_(23.71～26.92)V_(1.43～2.10)(As_(2.55～5.86),Sb_(0～0.63))_(3.15～5.95)(Sn_(0～2.6),Ge_(0～0.7))_(0.01～2.60)(Fe_(0～2.4),Zn_(0～0.24))_(0～2.4)S_(32),其中,存在Sb~(5+)?As~(5+)和Sn~(4+)?Ge~(4+)、(As,Sb)~(5+)+Cu~+?(Sn,Ge)~(4+)+(Fe,Zn,Cu)~(2+)以及V~(5+)?V~(4+)+Cu~+等复杂的元素耦合置换。结合矿石矿物组合及蚀变组合分析指出,酸性或略偏中性的、中低温高硫化态环境是促使硫锡砷铜矿生成的关键控制因素。     

A review of major non-sulfide zinc deposits in Iran

The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran.They include the Mehdiabad,Irankouh and Angouran world-class deposits,as well as the Zarigan and Haft-har deposits.These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift,karst development,changes in the level of the water table,and weathering.Zn(Pb)carbonates,Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics.Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling.The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite,hydrozincite,and hemimorphite as the main economic minerals,accompanied by iron and manganese oxy-hydroxides and residual clays.Commonly,non-sulfide minerals in these deposits consist of two types of ore:red zinc ore(RZO),rich in Zn,Fe,Pb-(As)and white zinc ore(WZO),typically with very high zinc grades but low concentrations of iron and lead.Typical minerals of the RZO are Fe-oxyhydroxides,goethite,hematite,hemimorphite,smithsonite and/or hydrozincite and cerussite.Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite.     

Study on the Cu–As–Sb–Ag–Bi–Pb–Te Sulfosalt Minerals from the Hydrothermal System of Southwestern Hokkaido,Japan

Shin‐Otoyo, Suttsu, Teine, Date, Chitose, and Koryu are sites rich in precious and base metal Miocene–Pleistocene epithermal deposits, and located in southwestern Hokkaido, Japan. The deposits are predominantly hosted by the Green Tuff Formation of Middle Miocene age. Ore petrographic study of these deposits shows the occurrence of variable quantities of Cu–As–Sb–Ag–Bi–Pb–Te sulfosalt minerals. Determination of mineralogical and chemical compositions of the sulfosalt minerals was undertaken to elucidate the time and spatial changes of the sulfide‐sulfosalt minerals. Various types of sulfosalt minerals identified from gold–silver and base metal quartz–sulfide veins represented some sulfosalt mineralization phases, such as the Cu–Fe–Sn–S phase of mawsonite and stannite; Cu–(As,Sb)–S phase of tetrahedrite–tennantite and luzonite–famatinite series minerals; (Cu,Ag)–Bi–Pb–S phase of emplectite, pavonite, friedrichite, aikinite, and lillianite–gustavite series minerals; (Ag,Cu)–(As,Sb)–S phase of proustite–pyrargyrite and pearceite–polybasite series minerals; and Bi–Te–S phase of tetradymite and kawazulite minerals. There are some trends in the paragenetic sequence of sulfosalt mineralization in southwestern Hokkaido (in complete or partial) as follows: sulfide → Cu–Fe–Sn–S → (Cu,Ag)–Bi–Pb–S → (Bi–Te–S) → Cu–(As,Sb)–S → ([Ag,Cu]–[As,Sb]–S). The formation of sulfosalt minerals is characterized by the introduction of some elements such as Sn, Bi, and Te at an earlier stage and an increase or decrease of some elements such as As and Sb, followed by the introduction of Ag at the later stage of ore mineral paragenesis sequence. Mineral composition of the Chitose and Koryu deposits are slightly different from those of Shin‐Otoyo, Suttsu, Teine, and Date due to their lack of Sn (tin) and Bi (bismuth) mineralization. The variable concentrations and relationships are not simply with redistributed trace elements from the original sulfide minerals of chalcopyrite, pyrite, galena, and sphalerite. Some heavier elements were also introduced during the replacement reaction, which is consistent with the occurrence of their associated minerals.     

The Discovery of Diamonds in Chromitites of the Hegenshan Ophiolite, Inner Mongolia, China

Diamond,moissanite and a variety of other minerals,similar to those reported from ophiolites in Tibet and northern Russia,have recently been discovered in chromitites of the Hegenshan ophiolite of the Central Asian Orogenic Belt,north China. The chromitites are small,podiform and vein-like bodies hosted in dunite,clinopyroxene-bearing peridotite,troctolite and gabbro. All of the analysed chromite grains are relatively Al-rich,with Cr# [100Cr/(Cr+Al)] of about 47–53. Preliminary studies of mainly disseminated chromitite from ore body No. 3756 have identified more than 30 mineral species in addition to diamond and moissanite. These include oxides(mostly hematite,magnetite,rutile,anatase,cassiterite,and quartz),sulfides(pyrite,marcasite and others),silicates(magnesian olivine,enstatite,augite,diopside,uvarovite,pyrope,orthoclase,zircon,sphene,vesuvianite,chlorite and serpentine) and others(e.g.,calcite,monazite,glauberite,iowaite and a range of metallic alloys). This study demonstrates that diamond,moissanite and other exotic minerals can occur in high-Al,as well as high-Cr chromites,and significantly extends the geographic and age range of known diamond-bearing ophiolites.     

巴丹吉林沙漠盐湖面积变化对湖泊边缘表层沉积物盐类矿物组合影响

选择巴丹吉林沙漠17个代表性盐湖,采集了2013年春季和秋季湖泊边缘表层沉积物样品,通过X衍射分析其盐类矿物组成和百分含量;应用Landsat 8遥感数据提取了上述两时段湖泊面积。结果发现,自春季到秋季13个面积减小的湖泊中,碳酸盐类矿物百分含量均较低,变化不明显;氯化物矿物和总盐类矿物百分含量均有增加,其增加幅度与湖泊面积变化有关。面积减少超过10%的湖泊,氯化物矿物或硫酸盐矿物百分含量总体明显增加;其余面积减少的湖泊,氯化物矿物百分含量均较春季有一定的增加,盐类矿物总百分含量也有一定程度的增加,但与湖泊面积减小程度相比没有更为明显的规律。4个面积增大的湖泊中沉积物的总盐类矿物百分含量和各盐类矿物的百分含量并未呈现显著相关性,表明在该区域湖泊面积的变化过程中,湖泊边缘表层沉积物中的盐类矿物百分含量对盐湖萎缩的指示意义相对高于湖泊扩张时期,氯化物矿物百分含量变化对湖泊面积萎缩变化响应更为敏感。     

山东旧店金矿金矿物特征及其意义

以山东平度旧店金矿床中金矿物作为研究对象,通过对金矿物的形态、物性、主成分及微量元素等特征的研究,认为旧店金矿中主要金矿物为银金矿、自然金,主要载金矿物为石英、黄铁矿、黄铜矿、方铅矿、闪锌矿等。金主要以银金矿形式产出,金银矿少量,自然金很少。金矿物赋存状态主要为裂隙金、包体金、晶隙金等,呈粒状、板状、针状产出,银金矿与石英、黄铁矿依存关系最为密切。旧店金矿金的成色集中在600～800之间,平均744.13,说明旧店金矿经历了中温成矿环境,且成矿时间较短,是以金石英多金属硫化物阶段为主成矿期。     

琼东南盆地物源和沉积环境变化的重矿物证据

基于11口钻井岩心样品的重矿物数据,结合古生物学、元素地球化学和地震资料,对琼东南盆地的物源及沉积环境演变进行了分析.结果表明,盆地基底沉积以陆相沉积为主,自渐新世起,盆地逐渐接受海侵,大致经历了海陆过渡→滨浅海→浅海→半深海的沉积环境演变过程,水深总体呈逐渐增大的趋势且在同一时期南部区域水深整体上大于北部.随着沉积环境的变化,各地层(崖城组至莺歌海组)物源呈现出多源性特征,经历了原地→近源→远源的演变过程.在渐新世早期,物源以近源玄武质火山碎屑和邻区陆源碎屑为主,之后演变为远源的陆壳碎屑,物源区包括北部海南岛、南部永乐隆起、东北部神狐隆起、西部红河、西南部中南半岛乃至更广的区域.海南岛物源自早渐新世便开始发育,至中中新世成为盆地最主要的物源,并持续至现今;永乐隆起和神狐隆起物源在晚渐新世至早中新世期间最为发育,于中中新世逐渐消退;红河物源于晚中新世大规模加入,为中央峡谷的主要沉积物源,影响至上新世结束;中南半岛莺西物源自上新世发育,影响至更新世时期.此外,自生组分对盆地(尤其是南部区域)的沉积贡献也不容忽视.