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1.
峨眉山玄武岩的铂族元素地球化学特征   总被引:38,自引:4,他引:34  
张成江  李晓林 《岩石学报》1998,14(3):299-304
采用镍锍试金预处理中子活化分析方法,系统地测定了峨眉山玄武岩的铂族元素含量。14个样品的平均值为:Os=0.39ng/g,Ir=0.0698ng/g,Ru=0.49ng/g,Rh=0.25ng/g,Pt=7.71ng/g,Pd=5.48ng/g。相对于原始上地幔,峨眉山玄武岩的铂族元素分异明显,Os、Ir、Ru、Rh亏损,Pt、Pd富集。(Pt+Pd)/(Os+Ir+Ru)比值(平均13.96)和Pd/Ir比值(平均78.5)显著高于原始上地幔、地幔捕虏体、阿尔卑斯型橄榄岩及科马提岩。铂族元素配分模式为铂钯富集型。以上这些特征表明其原始岩浆为上地幔低程度部分熔融形成的玄武岩浆。  相似文献   

2.
缅甸铂族金属砂矿中的矿物种类   总被引:1,自引:0,他引:1  
赵怀志  陈立新 《矿物学报》1994,14(3):285-291,T001
采用电子探针分析(EPMA),对缅甸铂族金属砂矿中的矿物种类进行了研究。物质组成研究查明:主要组合矿物是Pt、Ir、Os、Ru的自然元素和金属互化物。主要矿物是自然铂矿、铁铂合金、钌铱锇矿、等轴锇铱矿和铱锇矿。次要及稀有矿物是铂族金属的硫化物、砷化物、包括(Rh、Pd、Pt)2As和(Rh、Pd、Pt、Ni)2As两种陌生矿物、锑化物,以及含铂族元素的Fe、Ni、Cu硫化物。  相似文献   

3.
铂族元素地球化学标准物质的研制   总被引:12,自引:3,他引:9  
GPt_1~7系列标准物质由土壤、水系沉积物、富镁超基性岩、富铁超基性岩、含铜镍贫铂矿石及铬铁矿等不同类型7个样品组成。铂族元素的含量范围从土壤和岩石的背景含量到矿石达4~5个数量级。经方差检验样品均匀度良好。标准物质的定值分析采用了不同类型的试金和湿化学法分离富集,以原子吸收、催化比色、催化极谱、等离子体质谱、发射光谱和中子活化等方法进行测定。定值的元素为Pt、Pd、Os、Ru、Ir、Rh6个铂族元素及Au。该系列标准物质主要适于作铂族元素地球化学勘查和铂矿勘查中铂族元素分析的量值标准与测试的质量监控。  相似文献   

4.
金川铜镍硫化物矿床铂族元素的赋存状态及分布规律   总被引:17,自引:3,他引:14  
金川铜硫化物矿床铂族元素球粒陨石标准化型式属于Pt-Pd配分类型,Pt、pd〉Os、Ir、Ru、Rh,存在3种不同形式的图形;PGE(铂族元素)在熔离和深熔--贯入型岩矿体中,PGE含量从非含矿岩石→SN-B→SN-A2→SN-A1依次增加,显示与金属硫化物含量具有正消长关系;矿石中80%以上的铂和70T以上的钯呈矿物相存在;PGE富集体主要分布在富矿体膨大处的中、下部。  相似文献   

5.
云南墨江金矿和陕西煎茶岭金矿中Ag、Au和PGE(铂族元素)的丰度和共生状况如下:(1)两矿床中的Ag-Au关系呈三种情况:硅质岩型矿石和其他类型低品位金矿石中Ag-Au基本上不具相关关系;石英脉型矿石中Ag-Au呈明显的正相关关系;氧化矿石中Ag-Au呈负相关关系。(2)所有样品中的PGE均低于71×10(-6),其PGE的特征是Pt≥Pd和Ru>Os、Ir、Rh。(3)这些样品的地幔标准化PGE分布模式是以Rh为峰的上凸曲线,而墨江样品又具Ir的负异常。与一般超基性岩的情况不同,这些样品的模式曲线中Pd-Au部分呈陡弯折,它表明矿化元素金可能主要由区域成矿流体提供。  相似文献   

6.
与基性-超基性侵入体有关的Ni-Cu-PGE硫化物矿床是镍-铜-铂族元素矿床的最重要类型。传统观点认为,Ni-Cu-PGE硫化物矿床是由成矿岩浆分异演化、熔离形成的,与围岩性质关系不大。实际上,大部分基性-超基性岩浆是硫化物不饱和的,在岩浆自身演化过程中难以聚集大量硫化物而形成有经济价值的大型高品位NiCu-PGE硫化物矿床。因此,壳源硫的加入是基性-超基性岩浆中硫化物浓度达到过饱和,熔离形成Ni-Cu-PGE硫化物矿床的关键。膏盐层是富含石膏等硫酸盐(SO24-)的蒸发沉积建造,除SO24-外,还富含Cl-、CO23-、Na+、K+等盐类物质,在自然界分布广、面积大,是地壳中重要的硫源层和氧化障。但膏盐层在Ni-Cu-PGE硫化物矿床中的作用长期被忽视,制约了Ni-Cu-PGE硫化物矿床成矿找矿理论的发展。文章以世界最大的俄罗斯诺里尔斯克Ni-CuPGE硫化物矿床为例,介绍了膏盐层与矿床分布的空间关系、石膏等硫酸盐矿物在矿床和蚀变围岩中的分布、成矿元素和硫同位素组成特征及变化规律,阐明了膏盐层在成矿中的作用和控矿机理。膏盐(SO24-)的加入,可以大幅度提高成矿系统的氧逸度,将成矿岩浆中Fe2+氧化成Fe3+,形成铁氧化物,SO24-自身被还原,向成矿系统提供还原硫S2-,与Cu2+、Ni2+等结合,形成铜镍硫化物等,使基性-超基性成矿岩浆由硫化物不饱和变为过饱和,形成硫化物小液滴,在岩浆房经聚集-熔离-富集,形成岩浆型Ni-Cu-PGE硫化物矿床。除膏盐层外,富含硫化物的地层也是形成Ni-Cu-PGE硫化物矿床的重要硫源层。  相似文献   

7.
西秦岭寒武系硅岩建造喷流沉积作用与矿质聚集   总被引:3,自引:0,他引:3  
硅岩建造是西秦岭拉尔玛-邛莫层控金矿床的含矿岩系。含矿层状硅岩呈块状、条带状、层纹状、多孔状和同生角砾状等,单层厚度一般为30m-200m。主要成分SiO2平均含量高达95.30%,其余为FeO、Fe2O3和有机炭等。硅质的Al/(Al+Fe+Mn)比值低于0.35(平均0.153)。硅岩中微量元素十分丰富,不仅含具基性、超基性特征的元素群(如Cu、Cr、Pt、Pd、Os等),而且含具酸性特征的元素群(如W、Mo、U等).硅岩中稀土以总量低(32.9×10^-4~100×10^-4)、δCe亏损为特征.经北美页岩标准化后.稀土含量随原于序数的增大而增大.硅岩的δ180值为l7.60‰ ~23.24‰,其形成温度约为7O℃~l18℃.硅岩的δ30Si值主要在+O.4%~+O.8%之间,硅岩的上述特点均显示其与喷流沉积作用有美.喷流沉积作用不仅形成了特殊的硅岩建造,而且也使金等元素在硅岩建造中发生了明显的聚集。  相似文献   

8.
中子活化分析铂族元素的干扰反应问题   总被引:7,自引:0,他引:7  
探讨了中子活化分析铂族元素的一些干扰反应,如Au对Pt的干扰,U对Ru和Pd的干扰,并就Au对Pt的干扰程度进行了详细的计算。在照射时间为1d,中子注量率为1×1013n·cm-2·s-1的条件下进行计算,对于mPt/mAu=1的样品,Au对Pt的干扰达75%;mPt/mAu=10时,干扰达23%;mPt/mAu=20,干扰为13%,mPt/mAu=30,干扰降低为9%。这表明对于多数岩石样品Au干扰Pt相当严重,在采用中子活化法测定地质试样中Pt时必须对Au进行预分离。此外还就U对Ru和Pd的干扰情况进行了讨论,指出对于大多数超镁铁岩和硫化物矿石其干扰可以忽略或只需进行较小的校正,但对于基性岩和酸性岩就必须进行校正  相似文献   

9.
该铂-金砂矿产于超基性岩体山前谷地的第四纪冲积-洪积层中。在60年代,前人曾对该铂-金砂矿作过初步评价,但对其中的铂族元素矿物未进行过矿物学研究。笔者于1992年夏对该砂矿作了调研,并对吕明鸿工程师所提供的该砂矿的铂族矿物样品进行了物理光学性质研究及电子探针和X射线分析。业已查明,它们主要是铱锇矿、钉铱锇矿、锇铱矿、自然锇、等轴铁铂矿;矿物共生组合为自然金+上述铂族矿物+自然银+铬尖晶石+铬铁矿+磁铁矿+钛铁矿+辰砂。这表明,该铂-金砂矿的物质来源为含铬超基性岩。  相似文献   

10.
四川康滇地轴钒钛磁铁矿以大、中型为主,均分布在层状基性、超基性岩体中,该类型铁矿分为基性岩浆分异型和基性一超基性岩浆分异型2个亚类。对区域矿产三大成矿系列时空演化规律和钒钛磁铁矿含矿岩体的成矿系列进行了阐述,并从地质构造条件、含矿层状岩体的侵住、岩体生成时代及形成深度、围岩性质对成岩成矿的影响、岩浆来源、岩浆演化特征、岩体和矿床的成因等方面对钒钛磁铁矿成矿规律进行了探讨。  相似文献   

11.
采用ICP—MS方法分析了煎茶岭和金川硫化镍矿床岩石、矿石的铂族元素含量,煎茶岭岩体蛇纹岩的Cu/Pd比值低于原生地幔岩浆,说明岩浆熔离作用较弱,矿石的Pd/Ir比值较小,指示其多数矿石属于岩浆型,以岩浆成矿作用为主;而金川岩体的平均Cu/Pd比值远大于原生地幔岩浆,表明岩浆熔离作用强,矿石的Pd/Ir比值较大,体现了钯族元素矿化及成矿物质以幔源为主的特征。煎茶岭在成矿过程中有壳源物质的混染,整体上岩石、矿石铂族元素含量较低,这与岩浆熔离作用弱、铂族元素成矿作用不发育等因素有关;金川在成岩成矿过程中也有少量地壳物质的混染,但岩石、矿石铂族元素含量较高,反映了以岩浆深部熔离成矿作用为主的特征。  相似文献   

12.
金川超大型铜镍硫化物矿床的铂族元素地球化学特征   总被引:21,自引:2,他引:19  
对金川超大型铜镍岩浆硫化物矿床岩石、矿石的铂族元素地球化学特征研究表明 ,金川岩体的平均Cu/Pd值远大于原生地幔岩浆的Cu/Pd值 ,说明其岩石为因硫化物析离而失去Pd的岩浆所结晶 ;且岩石的PGE具有部分熔融趋势 ,与地幔橄榄岩接近 ,这些均指示存在岩浆熔离作用。该矿床岩石、矿石的PGE球粒陨石标准化分布模式比较对应 ,均可分为两种类型 ,反映了岩浆多次侵入、熔离分异同时成岩成矿的特征。另外 ,PGE S关系分析表明其成岩成矿过程中有少量地壳物质混染。PGE地球化学特征参数还指示了其高镁拉斑玄武质母岩浆的性质。  相似文献   

13.
The platinum-group element geochemistry of rocks and ores from Jinchuan super-large copper-nickel sulfide deposit is systemically studied in this paper. The Cu/Pd mean ratio of Jinchuan intrusion is lower than that of original mantle magma, which indicates that these ultrabasic rocks were crystallized from magma that lost Pd in the form of melting segregation of sulfides. The PGE of the rocks show trend of partial melting, similar to that of mantle peridotite, which shows that magma formation occurs during rock-forming and ore-forming processes. The chondrite normalized PGE patterns of the rocks and ores are well related to each other, which signifies the signatures of multi-episode magmatic intrusion, melting and differentiation in the formation processes of rocks and ores. In addition, analyses about the relation between PGE and S, and study on Re-Os isotopes indicate that few contamination of the crustal substances occurred during the magmatic intrusion and the formation of deposit. However, contamination by crustal substances helps to supply part of the S for the enrichment of PGE. Meanwhile, the hydrothermal process is also advantageous for the enrichment of PGE, especially lbr Pt and Pd, due to deep melting segregation. The characteristic parameters (such as Pt/(Pt+Pd), (Pt+Pd)/(Ru+Ir+Os), Pd/Ir, Cu/(Ni+Cu), and so on.) for platinum-group elements for Jinchuan sulfide copper-nickel deposit show the same features as those for sulfide copper-nickel deposit related to basic magma, which also illustrates its original magma property representative of Mg-high tholeiite. Therefore, it is the marie (not ultramafic) magma that resulted in the formation of the superlarge sulfide copper-nickel deposit enriched in Cu and PGE. To sum up, the geochemical characteristics of platinum-group elements in rocks and ores from Jinchuan copper-nickel sulfide deposit are constrained by the continental rift tectonic environment, the parent magma features, the enriched mantel magma source, the complex metallogenesis and PGE geochemical signatures, and this would be rather significant for the study about the genetic mechanism of copper-nickel sulfide deposits.  相似文献   

14.
金川铜镍硫化物矿床岩浆通道型矿体地质地球化学特征   总被引:7,自引:0,他引:7  
田毓龙  包国忠  汤中立  王玉山 《地质学报》2009,83(10):1515-1525
金川铜镍硫化物矿床6行富铜(铂族)矿体曾因Cu、Pt、Pd等含量明显高于相邻其它矿体而被认为是岩浆期后热液叠加作用的产物,研究发现,空间上该矿体受断层构造控制,在矿石组构、矿物组成和硫同位素组成方面与相邻岩浆融离型1号矿体一致,显示了该矿体岩浆成矿作用的特征。在元素地球化学方面,6行富铜(铂族)矿体的Cu、Ni、Pt、Pd含量及Cu/Ni比值明显高于1号主矿体,而Os、Ir、Rh、Ru却明显低于后者,同时,前者相对富含LREE,轻、重稀土分异程度高于后者。根据硫化物结晶分异过程中金属元素分配规律及稀土元素特征,阐明了6行富铜(铂族)矿体为岩浆通道型矿体,是岩浆硫化物晚期结晶的产物。矿区中西部存在的Cu、Ni、Pt、Pd、Au等含量高,而Os、Ir、Rh、Ru含量低的部位,是寻找岩浆通道型矿体的有利部位。  相似文献   

15.
The Binchuan area of Yunnan is located in the western part of the Emeishan large igneous province in the western margin of the Yangtze Block.In the present study,the Wuguiqing profile in thickness of about 1440 m is mainly composed of high-Ti basalts,with minor picrites in the lower part and andesites,trachytes,and rhyolites in the upper part.The picrites have relatively higher platinum-group element(PGE) contents(ΣPGE=16.3-28.2 ppb),with high Cu/Zr and Pd/Zr ratios,and low S contents(5.03-16.9 ppm),indicating the parental magma is S-unsaturated and generated by high degree of partial melting of the Emeishan large igneous province(ELIP) mantle source.The slightly high Cu/Pd ratios(11 000-24 000) relative to that of the primitive mantle suggest that 0.007%sulfides have been retained in the mantle source.The PGE contents of the high-Ti basalts exhibit a wider range(ΣPGE=0.517-30.8 ppb).The samples in the middle and upper parts are depleted in PGE and haveεNd(260 Ma) ratios ranging from -2.8 to -2.2,suggesting that crustal contamination of the parental magma during ascent triggered sulfur saturation and segregation of about 0.446%-0.554% sulfides,and the sulfide segregation process may also provide the ore-forming material for the magmatic Cu-Ni-PGE sulfide deposits close to the studied basalts.The samples in this area show Pt-Pd type primitive mantle-normalized PGE patterns,and the Pd/Ir ratios are higher than that of the primitive mantle(Pd/Ir=1),indicating that the obvious differentiation between Ir-group platinum-group elements(IPGE) and Pd-group platinum-group elements(PPGE) are mainly controlled by olivine or chromites fractionation during magma evolution.The Pd/Pt ratios of most samples are higher than the average ratio of mantle(Pd/Pt=0.55),showing that the differentiation happened between Pt and Pd.The differentiation in picrites may be relevant to Pt hosted in discrete refractory Pt-alloy phase in the mantle;whereas the differentiation in the high-Ti basalts is probably associated with the fractionation of Fe-Pt alloys,coprecipitating with Ir-Ru-Os alloys.Some high-Ti basalt samples exhibit negative Ru anomalies,possibly due to removal of laurite collected by the early crystallized chromites.  相似文献   

16.
Summary The Jinchuan deposit is a platinum group element (PGE)-rich sulfide deposit in China. Drilling and surface sampling show that three categories of platinum group element (PGE) mineralization occur; type I formed at magmatic temperatures, type II occurs in hydrothermally altered zones of the intrusion, and type III in sheared dunite and lherzolite. All ore types were analyzed for Os, Ir, Ru, Rh, Pd, Pt and Au, as well as for Cu, Ni, Co and S. Type I ore has (Pt + Pd)/(Os + Ir + Ru + Rh) ratios of <7 and relatively flat chondrite-normalized noble metal patterns; the platinum group minerals (PGM) are dominated by sperrylite and moncheite associated with chalcopyrite, pyrrhotite and pentlandite. Type II has (Pt + Pd)/(Os + Ir + Ru + Rh) ratios from 40 to 330 and noble metal distribution patterns with a positive slope; the most common PGM are sperrylite and Pd bismuthotelluride phases concentrated mostly at the margins of base metal sulfides. Type III ores have the highest (Pt + Pd)/(Os + Ir + Ru + Rh) ratios from 240 to 710; the most abundant PGM are sperrylite and phases of the Pt–Pd–Te–Bi–As–Cl system. It is concluded that the Jinchuan deposit formed as a result of primary magmatic crystallization followed by hydrothermal remobilization, transport, and deposition of the PGE.  相似文献   

17.
The rift-related, seaward-dipping reflector sequence (SDRS)SE of Greenland consists of basaltic lavas that exhibit variabledegrees of magmatic differentiation, derived from a heterogeneousmantle source. Platinum-group elements (PGE) are used to provideinsights into the petrogenetic evolution of the SDRS, and tocharacterize the magma sources. Noble metal concentrations correlatewell with indicators for magmatic differentiation (mg-number,MgO), exhibiting two distinct trends. Concentrations of Ir,Ru and Rh tend to decrease with progressive differentiation,indicating compatible behaviour of these elements during fractionalcrystallization processes. The variation of Pt and Pd showssegmented trends. In primitive magmas, Pt and Pd are incompatibleand become enriched in the melt. The primitive magma is S undersaturated,despite derivation from a depleted mid-ocean ridge basalt sourceat a moderate degree of melting, reflecting enhanced S solubilityin the melt caused by high Fe content and elevated temperature.In the more evolved lavas, Pt and Pd decrease with decreasingMgO and mg-number. This indicates that S saturation had occurredwith Pt and Pd being incorporated in sulphides, which probablysegregated during ascent. Bulk partition coefficients for thePGE during partial melting are calculated based on data froma primitive basaltic unit with MgO  相似文献   

18.
拉水峡铜镍矿床位于化隆基性—超基性岩带中,岩体几乎全岩发生铜、镍硫化物矿化,且已遭受强烈蚀变,以角闪岩为主。岩浆期主要金属硫化物矿物组合为磁黄铁矿、黄铜矿、镍黄铁矿;热液蚀变期主要有紫硫镍矿、黄铁矿、黄铜矿、针镍矿等;氧化表生期主要为含镍高岭石、含镍绿泥石、孔雀石等。矿石轻稀土元素富集和负Eu异常明显,说明岩浆演化过程中发生了大量斜长石等的分离结晶作用。∑PGE含量平均为2460.46×10-9,(Pd+Pt)/(Os+Ir+Ru)值为0.40~2.00,表明铂族元素与岩浆深部熔离作用密切相关;但Pt/Pd(0.01~2.62)、Pd/Ir(0.91~8.77)说明热液作用对铂族元素具有一定的富集作用。S同位素组成变化范围很小,δ34S平均值为2.24‰,硫化物中的S以地幔S为主。拉水峡矿床的形成经历了岩浆融离贯入、热液叠加改造及表生氧化作用3个阶段。  相似文献   

19.
Platinum-group element (PGE) geochemistry combined with elemental geochemistry and magnetite compositions are reported for the Mesoproterozoic Zhuqing Fe–Ti–V oxide ore-bearing mafic intrusions in the western Yangtze Block, SW China. All the Zhuqing gabbros display extremely low concentrations of chalcophile elements and PGEs. The oxide-rich gabbros contain relatively higher contents of Cr, Ni, Ir, Ru, Rh, and lower contents of Pt and Pd than the oxide-poor gabbros. The abundances of whole-rock concentrations of Ni, Ir, Ru, and Rh correlate well with V contents in the Zhuqing gabbros, implying that the distributions of these elements are controlled by magnetite. The fractionation between Ir–Ru–Rh and Pt–Pd in the Zhuqing gabbros is mainly attributed to fractional crystallization of chromite and magnetite, whereas Ru anomalies are mainly due to variable degrees of compatibility of PGE in magnetite. The order of relative incompatibility of PGEs is calculated to be Pd?<?Pt?<?Rh?<?Ir?<?Ru. The very low PGE contents and Cu/Zr ratios and high Cu/Pd ratios suggest initially S-saturated magma parents that were highly depleted in PGE, which mainly formed due to low degrees of partial melting leaving sulfides concentrating PGEs behind in the mantle. Moreover, the low MgO, Ni, Ir and Ru contents and high Cu/Ni and Pd/Ir ratios for the gabbros suggest a highly evolved parental magma. Fe–Ti oxides fractionally crystallized from the highly evolved magma and subsequently settled in the lower sections of the magma chamber, where they concentrated and formed Fe–Ti–V oxide ore layers at the base of the lower and upper cycles. Multiple episodes of magma replenishment in the magma chamber may have been involved in the formation of the Zhuqing intrusions.  相似文献   

20.
煎茶岭硫化镍矿床的铂族元素地球化学特征及其意义   总被引:8,自引:2,他引:8  
采用ICP-MS分析方法对煎茶岭硫化镍矿床岩石及矿石的铂族元素地球化学研究表明,煎茶岭矿床蛇纹岩的Cu/Pd值低于原生地幔岩浆的Cu/Pd值,说明岩浆熔离作用较弱,其Au/Pd值反映存在后期变质热液成矿作用镍矿石的Pd/Ir比值变化较小,指示其多数矿石属于岩浆型,尽管岩浆活动弱,但以岩浆成矿作用为主。该硫化镍矿床的铂族元素特征参数(Pt/(Pt Pd)、(Pt Pd)/(Ru Ir Os)、Pd/Ir及Cu/(Ni Cu)等)具有过渡特征,这与其处于过渡的构造环境、特殊的岩浆性质和复杂的成矿作用有关煎茶岭镍矿床成矿过程中有壳源物质的混染,整体上岩、矿石铂族元素含量较低,这与其岩浆熔离作用弱,PGE成矿作用不发育等因素有关  相似文献   

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