东昆仑尕林格铁矿床成因年代学及Hf同位素制约

尕林格矿床发育大量与铁多金属成矿关系密切的花岗闪长岩、石英二长岩、石英二长闪长岩和石英闪长岩体.LA-ICP-MS锆石U-Pb年代学表明石英二长闪长岩的年龄为228.3土0.5 Ma,石英二长岩的年龄为234.4±0.6 Ma.地球化学特征也较为相似,SiO2质量分数中等(58.4％～64.3％),w(FeOT)/w(MgO)偏低(0.62～1.38),A/CNK值(0.52～0.86)＜1,轻稀土富集,轻重稀土分馏明显,中等—强烈的负Eu异常(δEu为0.33～0.82),富集Rb,Th等大离子亲石元素,明显亏损高场强元素(Sr,P,Nb,Ta,Ti等),w(Rb)/w(Sr)为0.12～0.39,具有壳幔混合Ⅰ型花岗岩的特征.锆石Hf同位素组成表明,石英二长闪长岩的εHf(t)为-4.15～3.44,T2DM为1042～1523 Ma;石英二长岩εHf(t)为-5.06～1.7,T2DM为1157～1587 Ma,二者具有相同的岩浆来源,可能为壳幔混合岩浆作用的结果.综合研究认为尕林格铁矿床中三叠世岩体为东昆仑218～242 Ma俯冲—碰撞转换阶段,地幔底侵古老陆壳,幔源基性岩浆与壳源花岗质岩浆发生不同程度混合作用的产物,中高温岩浆流体与围岩发生水—岩反应是矽卡岩型矿体形成的主要因素.     

A reconnaissance of the Cu isotopic compositions of hydrothermal vein-type cop-per deposit, Jinman, Yunnan,China

The Jinman deposit is a low-temperature hydrothermal vein-type copper deposit, which occurs along faults and fractures within Middle Jurassic sandstone and mudstone units of the Lanping-Simao Mesozoic-Cenozoic basin of Yunnan Province. In this note, we report for the first time the Cu isotopic compositions of Cu-sulfides from the Jinman deposit. The data show large variations and low 65Cu values of 3.70‰ to +0.30‰, which are in sharp contrast to the 65Cu values of high-temperature magmatic-hydrothermal copper deposits (0.62‰ to +0.40‰) and the modern ocean-floor massive sulfide deposits (0.48‰ to +1.15‰). It is suggested that the Cu isotope fractionation at Jinman is affected mainly by the following factors, i.e. a low temperature of ore formation (150-286℃); a sedimentary source for ore materials; various stages of ore deposition; and involvement of organic matter in the ore-forming processes.     

浙江天台盆地下陈萤石矿床地质特征及 ESR 年代学

探讨浙江天台盆地下陈萤石矿床的矿床地质特征与成矿时代,为寻找成因类似的矿床提供理论依据。通过该矿床的野外地质特征和岩矿石显微镜下特征的研究,并利用热活化电子自旋共振测龄法对矿区内不同矿脉上与萤石共生的石英进行了测定,结果表明下陈萤石矿床为热液充填型脉状萤石矿床,成矿年龄平均为75．3±7．0 Ma,其成矿时代主要为晚白垩世。对浙江不同地区萤石矿床成矿时代的规律进行总结,显示浙江的萤石矿成矿时代呈现多期次性,在早白垩世早期、早白垩世晚期、晚白垩世均有成矿作用发生,主要集中在晚白垩世。     

Large selenium isotopic variations and its implication in the Yutangba Se deposit, Hubei Province, China

The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the \"redox model\" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.     

皖南黟县西坑银矿床地质特征及其成因

研究了西坑银矿床的矿体形态,矿石组成、结构、构造,成矿物理化学条件,银的赋存状态,矿区岩浆作用等矿床地质特征。研究了矿区及外围地层地球化学。通过地层地球化学和矿床地质特征的综合分析研究认为,从矿化前的热变质作用、矿化早期的透闪石和透辉石化,到晚期的硫化物矿化,是一次岩浆活动热事件引起的连续地质作用过程,成矿物质主要来源于岩浆流体,酸性的岩浆流体沿层间破碎带上升时,在化学活性相对较高的蓝田组富碳酸盐岩地层中交代充填成矿     

河南老湾金矿床40Ar/39Ar定年及铅同位素研究

河南老湾金矿床为桐柏山北坡金银成矿带的主要组成矿床 ,矿床分布受龟山岩组、老湾花岗岩和韧性剪切带控制。石英单矿物的 4 0 Ar/ 39Ar定年方法测得金矿床的成矿年龄为 ( 91.5± 1.0 ) Ma,即金矿床形成于燕山晚期。铅同位素的研究结果表明燕山晚期形成的老湾花岗岩为矿床形成提供了成矿热液和主要的成矿物质 ,龟山岩组变质岩为矿床的另一个物源     

云南普朗超大型斑岩铜矿特征及成矿模型

普朗斑岩铜矿床位于义敦岛弧带南端,是中国目前可以确定的印支期斑岩铜矿床的典型代表.矿床产于由石英闪长玢岩、石英二长斑岩小岩株组成的复式岩体中,通过野外观察和典型地质体的辉钼矿Re-Os年龄、黑云母Ar/Ar年龄和K-Ar年龄测定,确定成矿年龄为(213±3.8)～(216.0±1) Ma,为晚三叠世诺利期,表明普朗斑岩铜矿床的成矿作用在印支期完成.含矿岩体蚀变分带明显,由中心向外发育强硅化带(局部)→钾长石、黑云母化带→石英、绢云母化带→青磐岩化带(局部发育伊利石-碳酸岩化带).工业矿体主要产于石英二长斑岩中的钾长石、黑云母化带和石英、绢云母化带.矿床具有斑岩铜矿中下部细粒状浸染、中上部细网脉状浸染和顶部围岩中产出大脉状矿体的"三层楼"模式.其斑岩体、元素组合及矿化特征与蒙古的欧玉·陶勒盖斑岩铜矿可以对比,资源潜力巨大.     

西藏马攸木金矿床地质特征及成因初探

马攸木金矿床是西藏最近发现的首例大型独立岩金矿床.该文着重介绍了马攸木岩金矿床的矿体形态、矿石结构构造和矿石物质组分、金矿物的一般特征,并将马攸木金矿床的形成分为热液期、风化期和沉积期,其中与岩金矿形成有关的热液期至少可分为三个矿化阶段.论述了岩金矿床的流体包裹体特征、S和Pb同位素特征及Ar同位素年龄.初步认为该矿床属与地热活动有关的浅成中低温热液矿床.     

云南澜沧铅锌银多金属硫化物矿床地质特征及成因

澜沧铅锌银多金属矿床产于晚古生代板块内部的裂谷构造环境。矿床与偏碱性的中基性火山活动密切相关,受火山口附近的断裂、裂隙构造控制。矿床具明显的垂直分带,围岩蚀变种类繁多。成矿过程可划分为两期三个阶段。S、Pb、O、H同位素及流体包裹体的研究结果表明,成矿物质以深部来源为主,同时有围岩中物质的加入;成矿流体以岩浆水为主。成矿温度为350-160℃,压力约689巴。温度降低、f_s_2和PH值升高是引起矿质沉淀的主要因素。成矿方式以充填作用为主。该矿床为低温火山热液矿床。     

河南栾川中鱼库矽卡岩矿物学特征及地质意义

河南栾川中鱼库硫锌多金属矿床是近年来发现的矽卡岩型硫锌多金属矿床,为进一步探讨其成矿机制,本文以矽卡岩矿物为研究对象,开展了野外观察、岩矿鉴定和电子探针分析综合研究。研究表明,矿床成矿阶段可细分为早矽卡岩阶段、退化蚀变阶段(晚矽卡岩阶段)、石英-硫化物阶段、石英-碳酸盐阶段。该矿床矽卡岩为交代成因的钙矽卡岩,石榴子石以钙铁榴石-钙铝榴石系列为主,辉石以透辉石-钙铁辉石系列为主,帘石主要为绿帘石,角闪石为钙角闪石,绿泥石为铁镁绿泥石。石榴子石、辉石端元组分特征显示矽卡岩阶段成矿流体经历了从酸性到碱性、从还原到氧化的转变。随着流体演变,从退化蚀变阶段到石英-硫化物阶段,成岩成矿环境逐渐从氧化环境过渡到还原环境。石英-硫化物阶段是成矿主阶段,在此阶段金属硫化物大量富集和沉淀。     

黑龙江金厂金矿花岗斑岩锆石地球化学、U-Pb年代学及地质意义

为确定与金厂金矿成矿有关的岩浆类型、活动时限和构造背景,采用LA-ICP-MS技术对研究区花岗斑岩开展了锆石U-Pb年龄及原位微区微量元素测定。结果表明:锆石环带发育,wTh/wU值>0.4,具有岩浆锆石特征;锆石年龄分布于220Ma和103～123Ma 2个区间,代表了2期岩浆事件;对2种锆石分别命名为捕获岩浆锆石和新生岩浆锆石;锆石的地球化学和年龄信息显示捕获岩浆锆石的原岩为早三叠世花岗岩;锆石微量元素信息暗示花岗斑岩是早三叠世花岗岩高度熔融结晶分异、侵位于浅部氧化环境而形成,这一过程导致新生岩浆锆石负Eu异常程度降低。新生锆石加权平均年龄为(113.5±3.8)Ma,与成矿年龄一致,据此认为早白垩世的岩浆事件是金厂金矿成矿事件的直接原因,成矿背景为太平洋板块俯冲后的岩石圈伸展。     

班公湖—怒江成矿带西段尕尔穷铜金矿床辉钼矿Re-Os年龄及其地质意义

尕尔穷铜金矿床的夕卡岩矿体之下陆续发现花岗斑岩脉,该花岗斑岩与夕卡岩存在密切的成生联系.通过辉钼矿的Re-Os同位素年龄测定技术,确定其成矿年龄为86.79 Ma,成矿时代是晚白垩世,矿床形成于班公湖—怒江洋盆向南俯冲碰撞和雅鲁藏布江洋盆向北俯冲碰撞的间歇期;狮泉河结合带在晚白垩世处于同碰撞期,大量中酸性岩浆岩侵位事件...     

Pure CO2 fluids in the Sarekoubu gold deposit at southern margin of Altai Mountains in Xinjiang, West China

Sarekoubu gold deposit occurs in metamorphosed acid volcanic rocks and volcaniclastic rocks of Devonian Kangbutiebao Formation along the southern margin of Altai Mountains in Xinjiang, West China. Pyritization, silicification and carbonatization are developed in wallrocks, and main gold mineralization stages are pyrite-quartz stage (Ⅱ)and polymetallic sulfide stage (Ⅲ). Primary fluid inclusions are often seen in main gold mineralization stages, which are almost pure CO2 liquid inclusions (Lco2) under room temperature with high densities of 0.85--1.07 g/cm^3. CO2-rich inclusions (Lco2-LH2O) and H2O-rich inclusions (LH2O-LCo2)are subordinate. Fluid inclusions in stage Ⅰ (polymetallic sulfide stage) are more complex than in stage Ⅱ, containing CO2-CH4 system with -78.1-61.9℃ of solid CO2 melting temperatures and -33.7-17.7℃ of partial homogenization temperatures. The trapping pressures of high densities are estimated to be 150-350 MPa. Laser Raman microprobe was used to confirm the composition of pure CO2 liquid inclusions. δ^13C values of CO2 inclusions range from -10.73‰ to -21.15‰, which are similar to some of fluids in the mantle-derived minerals that contain surface organic carbon by subduction recycling. These characteristics differ from many hydrothermal gold deposits. CO2 fluids have a regional source related to post-collisional orogeny.     

云南金顶铅锌矿床中的有机质特征及成矿作用探讨

研究了金顶铅锌矿床中碳沥青的分布特征及可溶解有机质中饱和烃和芳烃的生物标志物特征,并进一步探讨了有机质与金顶铅锌矿床的关系,结果表明,无论从纵向还是横向上看,甚至是矿床内部有机质的分布特征来看,均与成矿元素的分布具有一致性.为了进一步探讨有机质在金顶铅锌矿床中的作用,对碳沥青作了电子探针分析,结果表明,不论胶结状碳沥青、鳞片状碳沥青还是后期充填的眼球-囊状碳沥青均含有大量的成矿元素,这些成矿元素的组分和它们所形成的矿石矿物类型,与该类碳沥青所在矿段的矿体的成矿元素组分和类型相一致.由于这些碳沥青产出的形态不同,因此在矿床形成中的作用也不尽相同.对矿床的形成具有重大意义的是肉眼下能够见到的胶结状碳沥青、脉状碳沥青、部分鳞片状碳沥青,这些碳沥青对成矿元素起着活化、迁移的作用,也起着沉淀成矿的作用;眼球状-囊状碳沥青是后期充填的产物,对矿床的形成起一定的改造作用;浸染状碳沥青多属于原生沉积碳沥青,对矿床的形成仅起一定的还原沉淀的作用.而有机质的还原作用对金顶铅锌矿床的形成起着极为重要的作用.     

云南兰坪-思茅盆地大平掌铜多金属矿床同位素地球化学与成矿年代学

大平掌铜多金属矿床是近年来在兰坪 -思茅盆地新发现的一个重要矿床 .该矿床产出于火山岩中 ,其构造背景及矿床地质特征均比较复杂 ,整个矿床由上部层状或透镜状的块状硫化物矿体和下部脉状及浸染状的矿体组成 .该矿床脉状矿体中石英流体包裹体Rb_Sr等时线年龄为 ( 1 1 8± 1 2 )Ma ,初始锶同位素组成为 ( 0 .70 80 0 7± 0 .0 0 0 0 3 7) ;流体包裹体研究表明成矿流体具有中低盐度 ( 2 .0～ 8.0wt %NaCl)和中低温度 ( 90～ 2 0 0℃ ) ;矿床中主要硫化物矿物的δ34S值在 - 0 .9‰～ 3 .5‰之间 ,集中在零值附近 .结合对以往的氢 -氧同位素和铅同位素研究结果的综合分析可以看出 ,大平掌矿床与区域内的脉状铜矿具有相似的地球化学特征 .因此认为大平掌铜多金属矿床为形成于燕山期的热液矿床 ,而不是前人认为的海底喷流沉积形成的块状硫化物矿床     

云南省马关县南当厂银铅锌矿床地质特征及找矿远景

南当厂银铅锌矿床位于超大型矿床都龙锡锌多金属成矿带最南端,是一以银矿为主的银铅锌矿床．经研究认为,矿床（体）赋存于区域变质绿片岩相带的中寒武统田蓬组第二段第二亚段（E2t2-2）上部的碳酸盐岩中,呈沿层展布的陡倾斜似层状矿体;经工程揭露和控制,揭露大小矿体共八个,其中③为主要矿体,规模最大．矿床的形成经历了沉积矿源层一区域变质热液改造一岩浆热液叠加等三个互相联系又继承发展的长期演化过程．碳质白云石大理岩中的层间断裂破碎带,是银铅锌矿床最有利的赋存空间．     

A new Euprox from the Late Miocene of Yuanmou,Yunnan Province,China,with interpretation of its paleoenvironment

The Yuanmou Basin of Yunnan Province is a hotspot for the research of early homind evolution and its environmental background.During the implementation of the Program“Research of the Origin and Evolution of Early Man and Its Environmental Baqckground” from 1998 to 2001,a huge quantity of hominoid and mammal fossils were collected.The present report systematically describes an Euprox robustus sp.nov.identified during the recent laboratory work on the collected material.Euprox is a group of earliest cervids with true antlers.The new species is the third one of the genus discovered in China.Judged by its morphologic characteristics,the new species feed on juicy and tender leaves of dicotyledon.It implies that the vegetation of its epoch in the Yuanmou Basin is a kind of southern subtropical evergreen forest and the climate is humid and temperate with evident seasonality.The latter is mostly influenced by the monsoon and secondly by the latitude.     

Helium isotopic compositions in fluid inclusions of the Gangxi fault belt in the Huanghua Depression, Bohai Bay Basin

Helium is a trace constituent in natural gases and is the lightest element of all rare gases. Formed during natural nuclear processes, helium is chemically stable. Due to its strong diffusibility and permeability, helium can be used as a very sensitive tracer. Helium has two natural stable isotopes, 3He and 4He. 3He originates from the universal nebulae when the earth was formed, and 4He mainly originates from the radioactive disintegration of elements in the crust, such as U and Th [1]. In…     

皖南大坞尖钨(钼)矿床地质特征及成因分析

大坞尖钨(钼)矿床是皖南地区新发现的小型钨(钼)矿床.该矿床的矿体主要呈似层状,主要赋存于蓝田组下段白云质灰岩和钙质泥岩中.赋矿围岩以强烈的绢云母化、硅化和碳酸盐化为特征,矿石矿物为白钨矿和辉钼矿,脉石矿物主要有石英和绢云母.矿床的形成可划分4个成矿阶段,即无水矽卡岩阶段、含水矽卡岩阶段、石英硫化物阶段和碳酸盐阶段.通过对矿床地质特征和控矿因素的综合分析研究,认为大坞尖钨(钼)矿床属矽卡岩-云英岩复合型热液矿床,研究区具有重要的找矿潜力.     

New discovery of submerged forest remains in Shenhu bay, Fujian Province, and its environmental significance

The authors have made a further investigation on the tidal-zone paleoforest remains found in the Shenhu bay,Fujian Province.By surveying (scale of 1:500) and numbering of the remains,65 tree trunks were found.They are relatively concentrated in three different regions from south to north.Their growing ages ranged from 45 a to 100a. 22 ancient trunks‘ sections with low degree of carbonization show that the paleoforest was composed of Keteleeria Carr., Morus L.and Gleditsia L.^14C dating shows that the paleoforest was living in 9420-6760 aBP.Later it stopped developing and was buried by the alluvial aggradation caused by the sea level rise.