共查询到20条相似文献，搜索用时 78 毫秒
1.
琼北地区花岗岩出露较少,多零星分布在翁田镇至大致坡镇一带。本次研究选取该区域的翁田岩体为研究对象,通过LA-ICP-MS锆石U-Pb定年,限定该岩体形成时代为245.1±2.4Ma,属于中三叠世。翁田岩体主要岩性为中粒斑状黑云母正长花岗岩,属于高钾钙碱性系列,具有高SiO2(74.57~76.15wt%)、高碱(Na2O+K2O=7.15~8.48wt%)、低MgO(0.19~0.31wt%)的特征,属于准铝质-过铝质花岗岩。岩石轻稀土富集,重稀土亏损,具强的负Eu异常,富集大离子亲石元素如Rb、Th、U、K等,明显亏损Nb、Ta,强烈亏损Ba、Ti、Sr、P,具高10^4Ga/Al、FeOt/MgO、K2O/Na2O比值和高(Zr+Nb+Ce+Y)含量,具有铝质A型花岗岩特征。结合区域资料,翁田铝质A型花岗岩的出现,表明海南岛在中三叠世处于伸展环境。 相似文献
2.
《地质学报》2015,(10)
碌础坝岩体位于秦岭构造带的西段,自内向外依次由含斑电气石黑云母二长花岗岩、含斑细粒黑云母二长花岗岩、似斑状黑云母二长花岗岩、中粗粒黑云母二长花岗岩和中粒黑云母石英闪长岩组成,岩体中岩浆暗色包体发育。LA-ICPMS锆石U-Pb定年显示,碌础坝岩体形成于早中生代,其岩浆演化可划分为中三叠世(235Ma)和晚三叠世(218~209Ma)两期。早期为中粒黑云母石英闪长岩,该期岩石SiO2含量较低,富碱,属于准铝质、高钾钙碱性系列,具有I型花岗岩的特征;晚期为黑云母二长花岗岩,具有高硅、富碱的特征,属于准铝质-弱过铝质、钾玄岩-高钾钙碱性I型花岗岩。从早到晚,岩石的稀土元素总量具有由高到低的变化趋势,两期岩石的稀土元素配分曲线均为轻稀土相对富集的右倾型,晚期黑云母二长花岗岩更亏损HREE,早期闪长岩负铕异常不明显,晚期花岗岩的负铕异常较为显著。两期岩石均富集K、Rb、Ba等大离子亲石元素,而相对亏损P、Nb、Ta、Ti等高场强元素。岩体中发育的岩浆暗色包体与寄主岩石的主要氧化物具有相关性,微量和稀土元素特征相似。岩体中黑云母二长花岗岩和中粒黑云母石英闪长岩的εNd(t)值分别为-8.0和-7.0,相应的tDM为1.43Ga和1.40Ga。早期中粒黑云母石英闪长岩的εHf(t)为-4.47~0.53,集中于-3~-1之间,tDM C主要为1.6~1.3Ga;晚期黑云母二长花岗岩的εHf(t)变化于-11.64~1.16,集中于-7~-2范围内,tDM C为1.7~1.4Ga。岩石地球化学和Nd-Hf同位素组成特征表明,碌础坝岩体的源区物质是以中元古代壳源物质为主,有少量年轻幔源组分的参与。该岩体与其北边的中川岩体在年代学、岩石地球化学和同位素组成上具有一定的相似性,因此,从岩浆作用角度考虑,该岩体的外围也可能与中川岩体的一样,具有金的成矿潜力。 相似文献
3.
闾井岩体是西秦岭"五朵金花"岩体群的成员之一。岩石类型主要为似斑状黑云母二长花岗岩、含斑黑云母二长花岗岩、中细粒黑云母二长花岗岩及粗粒黑云母二长花岗岩。对似斑状黑云母二长花岗岩、粗粒黑云母二长花岗岩和中细粒黑云母二长花岗岩的LA-ICP-MS锆石U_Pb定年分别获得221±1 Ma(N=20,MSWD=0.11)、221±1 Ma(N=24,MSWD=0.04)和218±1 Ma(N=15,MSWD=0.13)的年龄,表明该岩体形成于晚三叠世,其中似斑状黑云母二长花岗岩比中细粒黑云母二长花岗岩形成略早。该花岗岩的A/CNK=1.02~1.16,Na_2O+K_2O=7.65%~8.84%,K_2O/Na_2O=1.37~1.82,属于过铝质-强过铝质、高钾钙碱性-钾玄岩系列,为I型花岗岩。稀土元素配分曲线为右倾型,轻、重稀土元素分馏明显,具有显著的负Eu异常。地球化学上总体富集Rb、Th、K元素,不同程度亏损Sr、Nb、P、Ti元素。锆石饱和温度计算显示,闾井岩体成岩温度为736~818℃。该岩体与"五朵金花"岩体群中的中川岩体具有相似的形成时代及地球化学特征,表明闾井岩体与中川岩体可能具有相似的成岩机制,其外围可能也具有和中川岩体一样的成矿潜力。 相似文献
4.
西秦岭碌础坝岩体的锆石U-Pb年龄、成因及其地质意义 总被引：3，自引：0，他引：3
碌础坝岩体位于秦岭构造带的西段,自内向外依次由含电气石黑云二长花岗岩、含斑细粒黑云母二长花岗岩、似斑状黑云母二长花岗岩、中粗粒黑云母二长花岗岩和中粒黑云母石英闪长岩组成,岩体中普遍发育岩浆暗色包体。LA-ICPMS锆石U-Pb定年显示,碌础坝岩体形成于早中生代,其岩浆演化可划分为中三叠世（235Ma）和晚三叠世（218～209Ma）两期。早期为中粒黑云母石英闪长岩,该期岩石SiO2含量较低,富碱,属于准铝质、高钾钙碱性系列,具有I型花岗岩的特征;晚期为黑云母二长花岗岩,具有高硅、富碱的特征,属于准铝质-弱过铝质、钾玄岩-高钾钙碱性I型花岗岩。从早到晚,岩石的稀土元素总量具有由高到低的变化趋势,两期岩石的稀土元素配分曲线均为轻稀土相对富集的右倾型,晚期黑云母二长花岗岩更亏损HREE,早期闪长岩负铕异常不明显,晚期花岗岩的负铕异常较为显著。两期岩石均富集K、Rb、Ba等大离子亲石元素,而相对亏损P、Nb、Ta、Ti等高场强元素。岩体中发育的岩浆暗色包体与寄主岩石的主要氧化物具有相关性,微量和稀土元素特征相似。岩体中黑云母二长花岗岩和中粒黑云母石英闪长岩的εNd(t)值分别为-8.0和-7.0,相应的tDM为1.43Ga和1.40Ga。早期中粒黑云母石英闪长岩的εHf(t)为-4.47～0.53,集中于-3～-1之间,tDMC主要为1.6～1.3Ga;晚期黑云母二长花岗岩的εHf(t)变化于-11.64～1.16,集中于-7～-2范围内,tDMC为1.7～1.4Ga。岩石地球化学和Nd-Hf同位素组成特征表明,碌础坝岩体的源区物质是以中元古代壳源物质为主,有年轻幔源组分的参与。该岩体与其北边的中川岩体在年代学、岩石地球化学和同位素组成上具有一定的相似性,因此,从岩浆作用角度考虑,该岩体的外围也可能与中川岩体的一样,具有金的成矿潜力。 相似文献
5.
小秦岭华山复式岩基大夫峪岩体锆石U-Pb年龄、Hf同位素和地球化学特征 总被引：1，自引：0，他引：1
大夫峪岩体位于华北陆块南缘小秦岭地区,是小秦岭地区华山复式岩基的重要组成部分,其LA-ICPMS锆石U-Pb定年结果显示:粗粒黑云母二长花岗岩和中细粒黑云母二长花岗岩的成岩年龄分别为(142.6±1.4)Ma和(140.1±1.2)Ma。岩体的w(Si O2)=69.12%~73.58%,w(Na2O)=3.95%~4.40%,大于3.2%,K2O/Na2O=0.92~1.22,A/CNK=1.03~1.04,小于1.1,属于弱过铝质高钾钙碱性I型花岗岩。岩石的ΣREE含量较高,LREE富集,LREE、HREE分馏明显,有较弱的负Eu异常。此外,岩石富集K、Rb、Ba、Sr等大离子亲石元素,而相对亏损Nb、Ta、Hf、Ti、P等高场强元素。粗粒黑云母二长花岗岩的εHf(t)主要为-24~-18,TDM2主要为2.3~2.7 Ga;中细粒黑云母二长花岗岩的εHf(t)主要为-26~-16,其TDM2主要为2.3~2.9 Ga。岩石地球化学和Hf同位素组成特征表明,岩体主要由古老下地壳部分熔融形成,源区物质可能为新太古宙太华群,并在成岩过程中有幔源或新生地壳组分的参与。根据区域地质和动力地质背景的演化历史,笔者认为,大夫峪岩体的形成时代,与东秦岭地区的其他岩体的形成时代基本一致,均形成于晚侏罗世—早白垩世,与华北克拉通东部以及华南、长江中下游等地区晚中生代岩浆作用的时间基本一致,说明整个中国东部晚中生代岩浆活动可能受控于统一的大地构造背景,即古太平洋板块俯冲欧亚板块,从而使整个中国东部发生了构造体制的大转变。大夫峪岩体就是在这种构造体制转换过程中形成的。 相似文献
6.
马达加斯加中部Maevatanana、Andriamena和Beforona三条绿岩带共有上百处铬、镍、铁、金等金属矿点。对位于马达加斯加中北部绿岩带的Maevatanana西南部花岗岩体进行主量元素、微量元素、锆石LA-MC-ICP-MS U-Pb定年及Lu-Hf同位素分析。岩体主要由黑云母二长花岗岩构成,为准铝质到弱过铝质的高钾钙碱性系列花岗岩,富集Rb、Ba、K等大离子亲石元素(LILE),亏损Nb、Ta、Ti等高场强元素(HFSE),其稀土元素总量为∑REE=92.02×10-6,A/CNK=1.01。其内锆石LA-MCICP-MS U-Pb的年龄为739~767Ma,即中新元古代,其εHf(t)均为负值,揭示该矿区花岗岩体源区为陆壳。其中岩浆锆石和继承锆石的Hf同位素二阶段模式年龄相近,表明花岗岩源岩的形成时期和基底黑云角闪斜长片麻岩的原岩一致。地球化学性质显示花岗岩体为I型花岗岩,与埃达克岩类似。综合数据认为岩体形成于中-新元古代(824~720Ma)Rodinia超大陆裂解,伴随Mozambique洋闭合Tanzanian克拉通与印度Dharwar克拉通汇聚背景下的陆缘弧岩浆活动。 相似文献
7.
南秦岭华阳花岗岩LA-ICP-MS锆石U-Pb
年龄、地球化学和Hf同位素组成
——对五龙岩体群成因的约束 总被引：4，自引：0，他引：4
华阳岩体位于南秦岭中部地区,岩体主体岩性为黑云母二长花岗岩。对中粒黑云母二长花岗岩和细粒黑云母二长花岗岩的LA-ICP-MS锆石U-Pb定年分别获得214Ma±2Ma和228Ma±2Ma的年龄,表明该岩体形成于晚三叠世。华阳花岗岩属于弱过铝质和高钾钙碱性系列,具有I-A型花岗岩过渡的特征,A/CNK值为1.01~1.14,Na2O为3.15%~3.83%,K2O为3.04%~5.70%,K2O/Na2O为0.84~1.80,Mg#为0.24~0.48;稀土元素配分曲线表现为右倾型,轻、重稀土元素分馏明显,具有显著的Eu负异常。该花岗岩富集Rb、K、Pb、Sr等大离子亲石元素,亏损Zr、Hf、Ta、Nb、P、Ti等高场强元素,表明华阳花岗岩的物源以壳源物质为主。锆石饱和温度和Ti温度计等的估算显示,华阳岩体岩浆源区的初始温度为750~800℃。花岗岩的锆石εHf(t)值变化范围较小,为-6.17~2.27,平均值为-3.19;二阶段模式年龄TDM2为1.65~1.12Ga,加权平均值为1.46Ga,结合区域地质背景和前人研究成果认为,华阳花岗岩是早—中元古代古老地壳物质部分熔融的结果,伴有少量幔源物质的加入;岩体的形成与华南板块和华北板块碰撞有关,是同碰撞向后碰撞构造体制转变或后碰撞伸展早期的产物。 相似文献
8.
9.
北秦岭两河口岩体位于太白地区,侵位于秦岭群杂岩中,主要岩性为眼球状花岗岩、片麻状花岗岩和二长花岗岩。
本文研究的眼球状花岗岩和片麻状花岗岩的结晶年龄分别为928±19 Ma 和940±12 Ma,岩石中还保留古元古代至中元古代的
继承锆石。眼球状花岗岩含有富铝矿物石榴子石和白云母。岩石的A/CNK 多大于1.1,具有高Si、富铝的特征,属于高钾钙
碱性系列。岩石轻、重稀土分馏明显,具有中等负Eu 异常。岩石富集大离子亲石元素（Rb, Ba, K 等）、亏损高场强元素
（Nb, Ta, Ti 等）,具有明显的Ba, P, Sr 负异常。矿物学和地球化学特征显示眼球状花岗岩和片麻状花岗岩为S 型花岗岩。两河
口岩体初始Sr 同位素组成变化大,87Sr/86Sr(t)=0.701067~0.739451,具有较低的εNd(t)=-5.7~-3.3, 两阶段Nd 模式年龄为TDM2=
1.9~2.1 Ga。样品具有高的放射成因Pb 同位素组成,指示两河口岩体是壳源成因岩石,其源岩可能为秦岭群斜长角闪岩和
片麻岩。结合区域地质背景,认为两河口岩体源于新元古代陆壳碰撞晚期的构造转换阶段古老中下地壳的熔融作用,是对
Rodinia 超大陆汇聚事件的响应。 相似文献
10.
后河岩体位于华北克拉通南缘崤山北部,岩体侵位于太古宙太华超群地层中,主要岩性是黑云母石英二长岩和黑云母二长花岗岩。黑云母石英二长岩和黑云母二长花岗岩的锆石U-Pb年龄分别为(131.0±1.8) Ma和(127.3±1.0) Ma。地球化学特征表明二者均具有富钾(K2O/Na2O =1.00~1.51)、过铝(A/CNK =1.12~1.17)、贫镁(Mg#=26~34)的特征,属高钾钙碱性系列的过铝质花岗岩。轻重稀土元素分馏程度较高,富集轻稀土,亏损重稀土,总体富集大离子亲石元素(LILE)而亏损高场强元素(HFSE),Eu异常不明显(δEu=0.84~0.97),(La/Yb)N比值高。Hf同位素特征显示,εHf(t)具有明显的负值(-17.8~-9.5),TDM2主要集中在2.3~1.7 Ga。综上所述,早白垩世后河岩体是华北克拉通南缘加厚下地壳部分熔融的产物,形成于地壳由挤压加厚向伸展减薄转换的阶段。 相似文献
11.
E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
12.
奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提 相似文献
13.
S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours. 相似文献
14.
Most sulfide-rich magmatic Ni-Cu-(PGE) deposits form in dynamic magmatic systems by partial melting S-bearing wall rocks with variable degrees of assimilation of miscible silicate and volatile components, and generation of barren to weakly-mineralized immiscible Fe sulfide xenomelts into which Ni-Cu-Co-PGE partition from the magma. Some exceptionally-thick magmatic Cr deposits may form by partial melting oxide-bearing wall rocks with variable degrees of assimilation of the miscible silicate and volatile components, and generation of barren Fe ± Ti oxide xenocrysts into which Cr-Mg-V ± Ti partition from the magma. The products of these processes are variably preserved as skarns, residues, xenoliths, xenocrysts, xenomelts, and xenovolatiles, which play important to critical roles in ore genesis, transport, localization, and/or modification. Incorporation of barren xenoliths/autoliths may induce small amounts of sulfide/chromite to segregate, but incorporation of sulfide xenomelts or oxide xenocrysts with dynamic upgrading of metal tenors (PGE > Cu > Ni > Co and Cr > V > Ti, respectively) is required to make significant ore deposits. Silicate xenomelts are only rarely preserved, but will be variably depleted in chalcophile and ferrous metals. Less dense felsic xenoliths may aid upward sulfide transport by increasing the effective viscosity and decreasing the bulk density of the magma. Denser mafic or metamorphosed xenoliths may also increase the effective viscosity of the magma, but may aid downward sulfide transport by increasing the bulk density of the magma. Sulfide wets olivine, so olivine xenocrysts may act as filter beds to collect advected finely dispersed sulfide droplets, but other silicates and xenoliths may not be wetted by sulfides. Xenovolatiles may retard settling of – or in some cases float – dense sulfide droplets. Reactions of sulfide melts with felsic country rocks may generate Fe-rich skarns that may allow sulfide melts to fractionate to more extreme Cu-Ni-rich compositions. Xenoliths, xenocrysts, xenomelts, and xenovolatiles are more likely to be preserved in cooler basaltic magmas than in hotter komatiitic magmas, and are more likely to be preserved in less dynamic (less turbulent) systems/domain/phases than in more dynamic (more turbulent) systems/domains/phases. Massive to semi-massive Ni-Cu-PGE and Cr mineralization and xenoliths are often localized within footwall embayments, dilations/jogs in dikes, throats of magma conduits, and the horizontal segments of dike-chonolith and dike-sill complexes, which represent fluid dynamic traps for both ascending and descending sulfides/oxides. If skarns, residues, xenoliths, xenocrysts, xenomelts, and/or xenovolatiles are present, they provide important constraints on ore genesis and they are valuable exploration indicators, but they must be included in elemental and isotopic mass balance calculations. 相似文献
15.
《Applied Geochemistry》2001,16(2):137-159
Five hundred and ninety-eight samples of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) collected from a 188,000 km2 area of the central Barents region (NE Norway, N Finland, NW Russia) were analysed by ICP-AES and ICP-MS. Analytical results for Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y concentrations are reported here. Graphical methods of data analysis, such as geochemical maps, cumulative frequency diagrams, boxplots and scatterplots, are used to interpret the origin of the patterns for these elements. None of the elements reported here are emitted in significant amounts from the smelting industry on the Kola Peninsula. Despite the conventional view that moss chemistry reflects atmospheric element input, the nature of the underlying mineral substrate (regolith or bedrock) is found to have a considerable influence on moss composition for several elements. This influence of the chemistry of the mineral substrate can take place in a variety of ways. (1) It can be completely natural, reflecting the ability of higher plants to take up elements from deep soil horizons and shed them with litterfall onto the surface. (2) It can result from naturally increased soil dust input where vegetation is scarce due to harsh climatic conditions for instance. Alternatively, substrate influence can be enhanced by human activity, such as open-cast mining, creation of ‘technogenic deserts’, or handling, transport and storage of ore and ore products, all of which magnify the natural elemental flux from bedrock to ground vegetation. Seaspray is another natural process affecting moss composition in the area (Mg, Na), and this is most visible in the Norwegian part of the study area. Presence or absence of some plant species, e.g., lichens, seems to influence moss chemistry. This is shown by the low concentrations of B or K in moss on the Finnish and Norwegian side of the (fenced) border with Russia, contrasting with high concentrations on the other side (intensive reindeer husbandry west of the border has selectively depleted the lichen population). 相似文献
16.
Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA 总被引：1，自引：0，他引：1
The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources. 相似文献
17.
18.
19.
《Chemical Geology》2007,236(1-2):13-26
We examined the coprecipitation behavior of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides under two different fluoride forming conditions: at < 70 °C in an ultrasonic bath (denoted as the ultrasonic method) and at 245 °C using a Teflon bomb (denoted as the bomb method). In the ultrasonic method, small amounts of Ti, Mo and Sn coprecipitation were observed with 100% Ca and 100% Mg fluorides. No coprecipitation of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides occurred when the sample was decomposed by the bomb method except for 100% Ca fluoride. Based on our coprecipitation observations, we have developed a simultaneous determination method for B, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by Q-pole type ICP-MS (ICP-QMS) and sector field type ICP-MS (ICP-SFMS). 9–50 mg of samples with Zr–Mo–Sn–Sb–Hf spikes were decomposed by HF using the bomb method and the ultrasonic method with B spike. The sample was then evaporated and re-dissolved into 0.5 mol l− 1 HF, followed by the removal of fluorides by centrifuging. B, Zr, Mo, Sn, Sb and Hf were measured by ID method. Nb and Ta were measured by the ID-internal standardization method, based on Nb/Mo and Ta/Mo ratios using ICP-QMS, for which pseudo-FI was developed and applied. When 100% recovery yields of Zr and Hf are expected, Nb/Zr and Ta/Hf ratios may also be used. Ti was determined by the ID-internal standardization method, based on the Ti/Nb ratio from ICP-SFMS. Only 0.053 ml sample solution was required for measurement of all 9 elements. Dilution factors of ≤ 340 were aspirated without matrix effects. To demonstrate the applicability of our method, 4 carbonaceous chondrites (Ivuna, Orgueil, Cold Bokkeveld and Allende) as well as GSJ and USGS silicate reference materials of basalts, andesites and peridotites were analyzed. Our analytical results are consistent with previous studies, and the mean reproducibility of each element is 1.0–4.6% for basalts and andesites, and 6.7–11% for peridotites except for TiO2. 相似文献
20.
S. M. Moosavirad J. Rasouli M. R. Janardhana M. R. Moghadam M. Shankara 《Arabian Journal of Geosciences》2013,6(10):3623-3634
This paper discusses the result of the detailed investigations carried out on the coal characteristics, including coal petrography and its geochemistry of the Pabedana region. A total of 16 samples were collected from four coal seams d2, d4, d5, and d6 of the Pabedana underground mine which is located in the central part of the Central-East Iranian Microcontinent. These samples were reduced to four samples through composite sampling of each seam and were analyzed for their petrographic, mineralogical, and geochemical compositions. Proximate analysis data of the Pabedana coals indicate no major variations in the moisture, ash, volatile matter, and fixed carbon contents in the coals of different seams. Based on sulfur content, the Pabedana coals may be classified as low-sulfur coals. The low-sulfur contents in the Pabedana coal and relatively low proportion of pyritic sulfur suggest a possible fresh water environment during the deposition of the peat of the Pabedana coal. X-ray diffraction and petrographic analyses indicate the presence of pyrite in coal samples. The Pabedana coals have been classified as a high volatile, bituminous coal in accordance with the vitrinite reflectance values (58.75–74.32 %) and other rank parameters (carbon, calorific value, and volatile matter content). The maceral analysis and reflectance study suggest that the coals in all the four seams are of good quality with low maceral matter association. Mineralogical investigations indicate that the inorganic fraction in the Pabedana coal samples is dominated by carbonates; thus, constituting the major inorganic fraction of the coal samples. Illite, kaolinite, muscovite, quartz, feldspar, apatite, and hematite occur as minor or trace phases. The variation in major elements content is relatively narrow between different coal seams. Elements Sc,, Zr, Ga, Ge, La, As, W, Ce, Sb, Nb, Th, Pb, Se, Tl, Bi, Hg, Re, Li, Zn, Mo, and Ba show varying negative correlation with ash yield. These elements possibly have an organic affinity and may be present as primary biological concentrations either with tissues in living condition and/or through sorption and formation of organometallic compounds. 相似文献