豫西熊耳山地区吉家洼金矿床成矿物质来源探讨——碳、氧、硫、铅同位素地球化学证据

吉家洼金矿床位于豫西熊耳山金多金属矿集区中西部,矿体产出受断裂构造控制,属构造蚀变岩-石英脉型金矿床。为了查明吉家洼金矿床的成矿物质来源,本次对矿床的碳、氧、硫、铅等同位素进行了系统研究。研究结果表明,吉家洼金矿的δ~(13)C_(V-PDB)介于-10.3‰~-7.7‰之间,δ~(18)O_(V-SMOW)介于14.2‰~17.8‰之间,表明成矿流体中的碳来源于岩浆。硫化物δ~(34)S值介于-20.4‰~-5.4‰,表明硫来源于早白垩世花山花岗岩基,造成硫化物的δ~(34)S值呈现出较大负值的原因可能是在成矿过程中成矿流体物理化学条件的变化引起硫同位素发生分馏所致。铅同位素组成为~(206)Pb/~(204)Pb=17.042~18.149,~(207)Pb/~(204)Pb=15.333~15.575,~(208)Pb/~(204)Pb=37.675~38.868,与由新太古界—古元古界太华群岩石重熔形成的早白垩世花岗岩的铅同位素组成相似,具有壳幔混合源的特点。综合碳、氧、硫、铅等同位素的研究结果认为,吉家洼金矿床的成矿流体来源于岩浆热液,并有大气降水的加入;成矿物质主要来源于早白垩世花岗岩,矿床成因属岩浆期后热液脉状金矿床。     

山东范家庄金矿床S、Pb同位素组成及对成矿物质来源的示踪

范家庄金矿床是胶东地区牟乳金成矿带新近发现的一个金矿床。通过S、Pb同位素的对比与分析,对范家庄金矿床的成矿物质来源进行了探讨和研究。研究结果表明,范家庄金矿床矿石硫化物δ~(34)S值总体为9.8‰～12.3‰,极差为2.5‰,平均值10.9‰,具有岩浆热液硫的特征,且与其伴生的中基性脉岩相近,说明范家庄金矿床的矿石硫主要来自于岩浆热液,并与其伴生的中基性脉岩具有相应的继承性。硫化物矿石铅~(206)Pb/~(204)Pb=17.110～17.600,~(207)Pb/~(204)Pb=15.444～15.532,~(208)Pb/~(204)Pb=37.578～37.986,将数据投影到铅构造模式图上,成分点均落在地幔铅与造山带铅平均演化带之间,显示范家庄金矿床铅具有壳幔混合来源特征。硫、铅同位素反映范家庄金矿床的成矿物质来源于地壳和地幔的混合,且以地幔物质为主。     

甘肃花牛山铅锌银矿床成因：来自原位S、Pb同位素及微量元素的约束

甘肃花牛山铅锌银矿床位于中亚造山带中段的甘肃北山地区。本文在详细的野外观察和室内鉴定的基础上,将花牛山铅锌银矿床成矿阶段划分为石英-毒砂-黄铁矿(第Ⅰ成矿阶段)和石英-多金属硫化物(第Ⅱ成矿阶段)两个阶段;进一步将黄铁矿划分为三种类型,分别为第一种类型的胶状黄铁矿(Py0)、第二种类型的热液叠加交代特征的黄铁矿(Py Ⅰ)及第三种类型的热液黄铁矿(PyⅡ)。黄铁矿、磁黄铁矿的原位硫同位素研究表明,成矿从早到晚硫化物δ~(34)S值呈递增的规律,具有逐渐向岩浆硫演化的趋势;胶状黄铁矿δ~(34)S值为-9.37‰～-8.10‰,具有沉积(生物成因)硫的特征;成矿第Ⅰ阶段硫化物δ~(34)S值为-9.03‰～-7.03‰,成矿第Ⅱ阶段硫化物δ~(34)S值为-5.77‰～-4.88‰,成矿阶段具有沉积硫与岩浆硫混合来源的特征。黄铁矿、磁黄铁矿的原位铅同位素研究表明,成矿期硫化物的~(206)Pb/~(204) Pb值、~(207)Pb/~(204) Pb值、~(208) Pb/~(204) Pb值以及μ、ω等铅同位素特征值组成范围较窄,铅源为与岩浆作用有关的壳幔混合来源,且与壳幔混合来源的晚三叠世花岗岩中长石铅及其控制的矽卡岩型金矿硫化物铅同位素组成类似。黄铁矿原位微量元素研究表明,胶状黄铁矿(Py0) Co/Ni和S/Se 比值分别为0.004～0.34和3.43 × 10~4～34.84 × 10~4,Se含量为1.558 × 10~(-6)～15.82 × 10~(-6),表现为沉积成因黄铁矿的特征。具有热液叠加交代特征Py Ⅰ的Co/Ni和S/Se 比值分别为0.05～3.38、0.05 ×10~4～5.38 ×10~4,Se含量为10.09 × 10~(-6)～1070 × 10~(-6),数值分布范围广,总体上有别于沉积成因黄铁矿,类似于热液成因黄铁矿的特征。热液黄铁矿(Py Ⅱ)的Co/Ni和S/Se 比值分别为0.60-68.88、1.46 × 10~4～9.15 × 10~4,Se含量为5.938 × 10~(-6)-35.91 × 10~(-6),表现为热液成因的特征。综上研究,认为花牛山矿床经历了南华纪-震旦纪沉积胶状黄铁矿形成期和晚三叠世岩浆热液成矿期,胶状黄铁矿在成矿过程中提供了部分硫,成矿金属物质主要来自晚三叠世岩浆成矿热液,并认为矿床成因为岩浆热液型矿床。     

浙江淳安银山银铅锌多金属矿床硫铅同位素地球化学特征

银山银铅锌多金属矿是近几年来在该区域发现的中型以上的银铅锌多金属矿床,为地层-构造-岩浆综合控制型矿床。运用矿区的黄铁矿矿石S、Pb同位素示踪的方法探讨了矿床成矿物质来源。矿区黄铁矿和方铅矿的硫同位素组成δ34S值为-1.5‰~27.9‰,且硫同位素分布直方图中显示3种来源特征,指示成矿物质来源可能为海水、地层或岩浆。Pb同位素组成μ(~(238)U/~(204)Pb)值特征、Zartman构造模式、Δγ-Δβ成因分类研究表明,矿区矿石铅为幔-壳混源,指示物源主要来自于中生代岩浆热液,而非海底热液沉积物。综合表明银山银铅锌多金属矿床是中生代岩浆热液型矿床。     

新疆东准噶尔绿源金矿床地质特征与金成矿物质来源分析

绿源浅成低温热液型金矿床位于野马泉-琼河坝古生代岛弧带东段的琼河坝矿集区。赋矿地层为一套中酸性火山熔岩夹火山碎屑岩建造。矿体呈似层状、条带状、透镜状,多受断裂构造控制。其热液成矿作用可分为4个阶段:石英-黄铁矿阶段(S1)、石英(玉髓)-金-黄铁矿阶段(S2)、石英-金-多金属硫化物阶段(S3)、石英-碳酸盐阶段(S4)。金主要赋存于S2和S3阶段。本文对该矿床开展S、Pb同位素及硫化物稀土元素研究,拟揭示其成矿物质来源。结果表明,绿源金矿床金属硫化物的硫同位素组成比较稳定,δ34S集中于+0.2‰~+2.8‰,均值为+1.35‰,显示出岩浆硫的组成特征。矿石与围岩中硫化物的硫同位素δ34S值一致,表明硫可能来源于矿区巴塔玛依内山组火山岩地层。S2和S3阶段硫化物的铅同位素~(206)Pb/~(204)Pb=16.457~18.084、~(207)Pb/~(204)Pb=15.267~15.635、208Pb/~(204)Pb=36.472~38.379,另一件长石的Pb铅同位素~(206)Pb/~(204)Pb=18.546、~(207)Pb/~(204)Pb=15.509、208Pb/~(204)Pb=38.183,μ值介于9.11~9.58之间,ω值介于33.97~38.61之间。上述各铅同位素比值变化范围较大,远远大于正常铅同位素组成的变化范围。结合同位素组成特征及特征参数法认为绿源金矿床矿石Pb为异常Pb,铅源为混合来源,一部分来源于上地壳物质,一部分来源于地幔物质。硫化物稀土元素特征与火山岩类似,暗示成矿物质可能来源于火山岩地层。H、O同位素特征显示,绿源金矿成矿流体以大气降水为主,有少量岩浆水的加入。综合S、Pb同位素、稀土元素等分析,本文认为绿源矿区岩浆活动和成矿作用具有壳幔混合源特征,成矿物质具深源特征,主要直接来自赋矿火山岩。     

甘肃岗岔金矿床同位素地球化学特征及成矿物质来源探讨

岗岔金矿床为近年来新发现的中型受断裂构造控制的浅成低温热液矿床,为了探讨其成矿物质来源,对主矿脉Au3号脉矿体中的黄铁矿、赋矿围岩全岩的S、Pb同位素和矿脉中石英的H、O同位素进行了分析测试。结果显示,矿体中黄铁矿δ34S变化范围为0.6‰~1.3‰,均值为0.975‰,同位素组成比较均一,具有明显的幔源硫特征;矿体黄铁矿与赋矿围岩具有相近的Pb同位素组成,其206Pb/204Pb值为17.935~18.208(均值为18.090),207Pb/204Pb值为15.539~15.74(均值为15.568),208Pb/204Pb值为38.093~38.478(均值为38.280);μ值(238U/204Pb)介于为9.39~9.53,ω值为36.81~38.14,暗示其铅源为壳幔混合来源,且受造山作用与岩浆作用影响较为明显。矿脉中石英H、O同位素测试获得:δDH2O值为-88.6‰~-76.7‰(均值为-80.92‰),δ18OH2O值为6.53‰~8.63‰(均值为7.46‰),显示出岗岔金矿床成矿热液流体主要来自岩浆,混有少量大气降水。上述S、Pb、H、O同位素特征表明岗岔金矿床成矿物质和流体来自壳幔混源且以幔源为主。     

上黑龙江盆地虎拉林金矿床硫、铅同位素特征及其成因探讨

虎拉林矿床位于中亚造山带东段额尔古纳地块之上,处于上黑龙江盆地西侧,东与砂宝斯、老沟等金矿床相邻。矿床载金矿物主要为薄膜状、粒状及脉状黄铁矿,成矿与早白垩世花岗斑岩、石英斑岩及隐爆角砾岩有密切联系。在对矿床详尽的野外工作基础上,通过对金属硫化物硫、铅同位素分析研究,探讨成矿物质来源,揭示矿床成矿规律。研究结果表明,上黑龙江盆地虎拉林矿床矿石及围岩中黄铁矿δ34SV-CDT分布于0.7‰~2.2‰,平均为1.18‰,集中于1.0‰左右,呈塔式分布,显示主要为岩浆硫特征;铅同位素206Pb/204Pb、207Pb/204Pb、208Pb/204Pb值分别为18.468~18.511、15.578~15.625、38.215~38.370,分布范围较小,且具有造山带铅特征。铅同位素μ值为9.41~9.50,均小于9.58;ω值为35.04~35.93,均值35.49,小于正常铅ω值;Th/U为3.60~3.66,显示出具有壳幔混源特征;在铅同位素构造环境判别图中,显示出具有下地壳部分熔融的特征;Δγ-Δβ图解显示矿床铅来源于上地壳与地幔混合带俯冲岩浆作用成因的铅同位素源区。综合矿床类型、矿体产出特征、矿体及围岩硫、铅同位素特征认为,虎拉林金矿区成矿物质主要来源于下地壳物质熔融形成的深部岩浆,同时存在上地幔与上地壳部分熔融物质的参与,成矿过程与早白垩世岩浆活动关系密切,形成于蒙古—鄂霍茨克洋闭合后伸展环境背景下。     

湖南康家湾铅锌多金属矿床地质地球化学特征与成因分析

康家湾铅锌多金属矿床位于湖南水口山矿田的东部,是矿田内最大的铅锌金银矿床,以铅锌为主,共伴生金银矿。通过硫、铅、氢-氧同位素研究,显示金属硫化物硫同位素δ~(34)S(-4.3‰～+2.1‰)主要变化范围为0～+3‰,说明本区硫化物硫同位素组成具有岩浆硫的特征(δ~(34)S=0‰);矿石铅同位素组成~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb、~(208)Pb/~(204)Pb比值分别变化于18.182～18.840、15.180～15.96、37.892～39.499之间,显示具有正常铅特点;在构造分配模式图解和构造环境判别图中,本区矿石铅同位素的投点均分布于上地壳演化线、造山带演化线和地幔演化线之间,暗示其铅同位素属于壳幔混合型铅;在Δγ-Δβ成因分类图解中,本区矿石铅同位素投点均分布于岩浆作用范围内,反映本矿床的成矿流体来源于岩浆岩;而氢-氧同位素表明,康家湾铅锌矿床成矿流体是多源的,主要由大气降水和岩浆水混合而成,早期以岩浆水为主,后期混入大量的大气降水。从而证明康家湾铅锌多金属矿床的形成与岩浆侵入活动有着密切的成因关系,应属于中低温岩浆热液型铅锌多金属矿床。     

黔西南紫木凼金矿床成矿物质来源:S⁃C⁃O⁃Pb⁃Sr同位素制约

紫木凼金矿床是黔西南卡林型金矿区一个重要的大型金矿床,其成矿物质来源尚不明确.对紫木凼金矿床不同类型矿石和赋矿围岩进行了S、C、O、Pb和Sr同位素组成对比研究.矿石中硫化物的δ34S值为-13.49‰~17.91‰（主要为-0.99‰~3.58‰）,赋矿围岩的δ34S值为-26.23‰~-19.63‰,矿床成矿期硫主要来源于岩浆,部分来源于赋矿地层中成矿前黄铁矿.热液期方解石的δ13C和δ18O分别为-9.10‰~0.59‰和15.65‰~23.82‰,与赋矿围岩、区域地层的碳、氧同位素组成差别较大,成矿流体的碳、氧部分来源于碳酸盐岩溶解,部分可能来源于岩浆.矿石中硫化物的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.064~18.973、15.585~15.670和38.219~39.054,赋矿围岩的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.136~18.650、15.574~15.656和38.423~38.812,矿石铅的来源较复杂,赋矿地层和岩浆可能都为其提供了部分铅.矿石中石英和方解石（87Sr/86Sr）_i比值为0.707 26~0.708 11,赋矿围岩的（87Sr/86Sr）_i比值为0.707 28~0.707 31,成矿流体中的锶主要来源于赋矿地层.紫木凼金矿床成矿物质具壳幔混合来源特征,成矿物质主要来自矿床深部隐伏岩浆岩,部分来自二叠系-三叠系赋矿地层.      

赣南西华山钨矿床硫、铅同位素组成对成矿物质来源的示踪

为明确西华山钨矿床成矿物质的来源,本文以矿床中的硫化物和钾长石为研究对象,通过硫化物中硫、铅同位素的研究,对矿床成矿物质来源进行探讨。结果表明,矿石中黄铁矿δ34S值为-2.1‰~0.4‰,辉钼矿δ34S值为4‰~7.9‰,硫主要来源于岩浆。辉钼矿、黄铁矿、钾长石的206 Pb/204 Pb值分别为18.718~18.849、18.640~18.745、18.698~18.792;207Pb/204Pb值分别为15.762~15.770、15.704~15.747、15.697~15.724;208 Pb/204 Pb值分别为39.094~39.134、38.902~39.056、38.904~39.012。由此判断矿床中矿石铅与岩石铅同位素组成具有同源关系,矿石铅主要来自与岩浆作用有关的上地壳;成矿物质来源于上地壳重熔形成的花岗岩浆,即上地壳岩浆侵位,为成矿作用提供部分成矿物质,同时也暗示成矿物质是由体现壳源特征的西华山复式岩体提供。     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

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.     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

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     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

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.     

Roles of xenomelts,xenoliths, xenocrysts,xenovolatiles, residues,and skarns in the genesis,transport, and localization of magmatic Fe-Ni-Cu-PGE sulfides and chromite

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.     

Regional distribution of Al,B, Ba,Ca, K,La, Mg,Mn, Na,P, Rb,Si, Sr,Th, U and Y in terrestrial moss within a 188,000 km2 area of the central Barents region: influence of geology,seaspray and human activity

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).     

Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA

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.     

Petrographic, mineralogy, and geochemistry of coals of Pabedana, Kerman Province, Central Iran

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.