Bacterially-mediated weathering of crystalline and amorphous Cu-slags

Two types of Cu-slags (CS: crystalline massive slag and GS: granulated amorphous slag) exhibiting a different chemical and mineral phase composition were compared with respect to their susceptibility to bacterial weathering using Pseudomonas aeruginosa (n° CIP 105094). Abiotic conditions e.g. sterile growth medium and ultrapure water were used for comparison. The experiments were extended up to 112 days with a systematic liquid phase renewal every 14 days. The results revealed significant release of elements in the bacterially mediated weathering experiments. Concentrations of elements (Si, Fe, Cu, Zn and Pb) in the biotic solutions were increased at least by 20% up to 99% compared to abiotic ones. From 3 to 77% of the leached elements were associated to the fraction >0.22 μm. Scanning electron microscope observations demonstrated greater weathering of mineral phases in biotic experiments than in abiotic ones which is in accordance with the solution chemistry exhibiting higher concentrations of elements leached in biotic set-ups. In the case of CS, glass and sulfides weathering was yet observed in abiotic experiment, whereas partial dissolution of fayalite (Fe₂SiO₄) was solely affected by the presence of bacteria. GS having a higher bulk content of metallic elements was found to be more stable than sulfide-bearing CS, while its (GS) glass matrix was found to weather easier under biotic conditions.     

Application of Zn isotopes in environmental impact assessment of Zn–Pb metallurgical industries: A mini review

Zn and Pb smelters are the major contributors to Zn and Pb emissions among all anthropogenic sources, thus, it is essential to understand Zn isotopic variations within the context of metallurgical industries, as well as its fractionation in different environments impacted by smelting activities. This mini review outlines the current state of knowledge on Zn isotopic fractionation during the high-temperature roasting process in Zn and Pb refineries; δ⁶⁶Zn values variations in air emissions, slags and effluents from the smelters in comparison to the geogenic Zn isotopic signature of ores formation and weathering. In order to assess the environmental impact of these smelters, the available and measured δ⁶⁶Zn values are compiled for smelter impacted natural water bodies (groundwater, stream and river water), sediments (lake and reservoir) and soils (peat bog soil, inland soil). Finally, the discussion is extended to the fractionation induced during numerous physicochemical reactions and transformations, i.e. adsorption, precipitation as well as both inorganic and organic surface complexation.     

Water-rock-tailings interactions and sources of sulfur and metals in the subtropical mining region of Taxco,Guerrero (southern Mexico): A multi-isotopic approach

Multi-isotope (H, O, S, Sr, Pb) systems coupled with conventional (major and trace element) hydrogeochemical analysis were applied to determine the origin of water, to model water-rock-tailings interactions and for source apportionment of sulfur and associated toxic metals in the mining region of Taxco, Guerrero in southern Mexico. Oxygen and H isotopes indicate that meteoric water in the zone is rainwater undergoing varying degrees of isotopic fractionation by atmospheric evaporation whereas Sr isotopes trace the interaction of pristine water from volcanics of the regional recharge zone and subsequently flowing through sandstone and shale to spring points. Leachates form from two distinctive sources (spring water and surface water) having differential interactions with bedrocks prior to entering the tailings. Compared to pristine water, leachates are enriched in sulfate, metals (e.g. Fe, Mn, Pb and Zn) and metalloids (e.g. As). The sulfur isotopic composition of ore-sulfides, leachates, secondary precipitates, regional surface water and hypogenic sulfates is described in terms of a two-component mixing model with shale of Mexcala and limestone of Morelos formations representing the light and heavy end-members, respectively, whereas Sr isotopic composition is bracketed combining three lithogenic (Mexcala/Morelos, Tilzapotla and Taxco Schist) sources. Finally, leachates have a mixture of lead from ore-sulfides and Taxco Schist Formation (Family I) or from ore-sulfides alone (Family II). The application of multiple environmental isotopic techniques is an outstanding tool for elucidating complex interactions of water with bedrocks and tailings and for determining the source of sulfur and toxic metal from mining and other metal polluted environments.     

岩石中的压力影形成的实验观测研究

野外地质观察发现,在大陆地壳变质岩中可以广泛观察到围绕一个大的单晶或者硬质点的两端区域填充低粘度相物质形成的压力影。为了定量研究岩石材料中压力影的形成条件,本文利用高精度Paterson气体介质变形装置,对含有刚性球的圣卡罗橄榄石和洋中脊玄武岩(MORB)的混合物圆柱型样品进行了高温高压扭转变形试验。变形实验前样品的初始熔融均匀分布,比例为φ≈0.05,变形试件尺寸为D8.9mm×L5.5mm,内含8粒直径约1mm的刚性球。扭转变形试验温度为1473K,围压为300MPa,应变率为γ≈1×10~(-4)s~(-1),最大剪切变形为γ≈4。实验结果表明,岩石受到扭转力的作用产生变形之后,当局部剪切应变达到γ≈1时,可以在刚性球周围形成熔融富集带和熔融贫乏带,即压力影构造,围绕刚性球对称分布。由于熔融分布的不均一性,富集带熔融比例上升,最高可以达到φ_(high)=0.1~0.3,熔融贫乏带熔融比例下降,含量为φ_(low)=0.01~0.02。由于刚性球对其周围的压力分布的扰动区域大约为刚性球的尺度范围,因此,在离开刚性球一定距离后,熔融趋于均匀分布。     

Geochemical and Geochronological Constraints on the Origin of the Meta-basic Volcanic Rocks in the Tengtiaohe Zone,Southeast Yunnan

The meta-basic volcanic rocks in the Tengtiaohe Zone yield zircon U–Pb ages of 258.8±2.5 Ma and 259.2±1.8 Ma, respectively which agree with the ages of flood basalts of ELIP and are similar to the basaltic rocks and komatiites from the Song Da Zone in northern Vietnam. The results suggest that the age of meta-basic volcanic rocks is Late Permian, rather than the Early Permian or Early Carboniferous ages as previously inferred. Most meta-basic volcanic rocks are strongly enriched in LREEs relative to HREEs and display trace element patterns similar to the ELIP high-Ti basalts, and are enriched in LILEs with negative Sr anomalies. Their initial ~(87)Sr/~(86) Sr ratios range from 0.705974 to 0.706188 and εNd(t) from-0.82 to-2.11. Their magmas were derived from an enriched and deep mantle source without significant crustal contamination. These meta-basic volcanic rocks formed in ELIP. Therefore, the Tengtiaohe Zone is not an ophiolite zone and can link to the Song Da Zone in northern Vietnam.     

黑河新生地区中侏罗世花岗质岩石锆石U-Pb年龄、地球化学特征及岩石成因

黑河新生地区西古兰河以北二长花岗岩的LA-ICP-MS锆石U-Pb同位素测试结果表明,其形成时代为中侏罗世((163.8±1)Ma)。这些中侏罗世二长花岗岩属于弱过铝质高钾钙碱性系列的Ⅰ型花岗岩,明显富集大离子亲石元素(Rb、Ba、Th)和亏损高场强元素(Zr、Hf、Nb、Ta),元素Sr具有明显的负异常,表明其原始岩浆起源于地壳火成岩的部分熔融。结合区域资料同时代火成岩的组合特征和古太平洋板块的构造演化,认为该二长花岗岩形成于活动大陆边缘,而其形成的地球动力学背景可能为古太平洋板块向欧亚板块俯冲造山后的伸展环境。     

西天山Muruntau金矿床地质和S-Pb同位素示踪

Muruntau金矿床位于乌兹别克斯坦卡拉库姆板块北缘,是世界规模最大的金矿床。赋矿地层为一套发生绿片岩相浅变质作用的含炭复理石建造。矿区主要经历了四期变形变质作用(D1-D4),矿体受构造控制明显,就位于桑格龙套-塔姆德套与穆龙套-道古兹套剪切带的构造交汇部位,金矿化主要产于次级韧脆性断裂中。对矿床的矿石硫化物及地层开展了系统S、Pb同位素研究,结果表明石英脉型及蚀变岩型矿石中硫化物的δ34S变化范围较大,集中于2.2‰~6.1‰,其中蚀变岩型矿石中毒砂样品δ34S值集中于2.2‰~4.6‰,含金石英脉中硫化物样品δ34S值集中于3.0‰~6.1‰,方解石-石英脉中硫化物样品δ34S值集中于3.5‰~4.0‰,表明矿石中硫主要来源于地层,可能有少量岩浆硫加入。2件黑色页岩中毒砂206Pb/~(204)Pb为19.906~20.378,~(207)Pb/~(204)Pb为15.730~15.750,208Pb/~(204)Pb为38.388~39.894;3件含金石英脉中黄铁矿206Pb/~(204)Pb为18.848~19.431,~(207)Pb/~(204)Pb为15.669~15.736,208Pb/~(204)Pb为38.346~38.879;2件方解石脉中毒砂206Pb/~(204)Pb为18.715~19.563,~(207)Pb/~(204)Pb为15.639~15.740,208Pb/~(204)Pb为38.640~39.295。6件地层岩石样品的铅同位素组成206Pb/~(204)Pb为19.416~20.600,~(207)Pb/~(204)Pb为15.675~15.746,208Pb/~(204)Pb为38.876~39.431。矿石铅与地层铅均落于上地壳与造山带之间,矿石铅显示较大的跨度,且与地层岩石铅具有部分重合,显示成矿物质具有双重来源,与赋矿地层及造山期变质流体均表现出密切成因联系。结合矿床地质特征总结分析,沉积地层的物质准备+多期构造运动驱动变质流体运移(D1-D4)+岩浆热液的后期叠加应该是Muruntau巨量金属富集的关键控制因素。     

高放废物处置库新疆阿奇山预选地段区域水文地质特征

新疆阿奇山地区是我国高放废物处置库预选地段之一。在野外调查、样品采集和测试的基础上,讨论了该地段区域水文地质特征,结果表明,阿奇山地段地下水可划分为松散岩类孔隙水、碎屑岩类裂隙孔隙水和基岩裂隙水3种类型,其单井涌水量一般10m~3/d,属于典型的低含水介质;区域地下水流向为自南东流向北西;位于吐鲁番盆地的艾丁湖一带为阿奇山地段地下水的最终排泄区。     

四川会理天宝山矿床深部新发现铜矿与铅锌矿的成因关系探讨

天宝山矿床是川滇黔接壤铅锌矿集区内的代表性铅锌矿床之一,赋存于上震旦统灯影组白云岩中。近年来,该矿床深部发现了以铜为主的矿化,甚至形成铜矿体。目前,对铜矿成因及其与铅锌矿的关系尚不清晰。本文报道新发现铜矿的矿物学和同位素地球化学资料,以期揭示铜矿的成矿物质来源,结合铅锌矿的相关研究,探讨铜矿形成机制及其与铅锌矿的成因关系。镜下观察和扫描电镜分析显示,铜矿石中主要金属矿物为黄铜矿和银黝铜矿,其次为方铅矿和毒砂,含少量闪锌矿和黄铁矿;铅锌矿石中闪锌矿是主要金属矿物,方铅矿和黄铁矿次之,含少量黄铜矿和深红银矿。铜矿石中闪锌矿主要呈半自形-他形粒状,与黄铜矿共生或被其包裹,方铅矿主要呈细脉状充填在黄铜矿、银黝铜矿和毒砂的裂隙中或呈他形粒状分布在这些矿物中;铅锌矿石中黄铜矿主要呈浸染状分布于闪锌矿之中。两类矿石金属矿物的组构特征,显示铜矿物与铅锌矿物具有密切的共生、穿插和包裹关系,应属同期成矿。同位素地球化学数据显示,铜矿石中黄铜矿的δ34SCDT值为3.9‰~4.2‰(均值为4.1‰,n=3),铅锌矿石闪锌矿的δ34SCDT值为3.3‰~3.9‰(均值为3.5‰,n=3),十分相近,暗示它们具有相似的S源,应均属赋矿地层海相蒸发岩中硫酸盐热化学还原作用的产物。铜矿石中黄铜矿的~(206)Pb/~(204)Pb=18.441~18.476(均值为18.461,n=3),~(207)Pb/~(204)Pb=15.731~15.751(均值为15.741,n=3),~(208)Pb/~(204)Pb=38.809~38.873(均值为38.849,n=3),μ=9.72~9.76;铅锌矿石中方铅矿的~(206)Pb/~(204)Pb=18.442~18.480(均值为18.455,n=3),~(207)Pb/~(204)Pb=15.746~15.763(均值为15.752,n=3),~(208)Pb/~(204)Pb=38.793~38.892(均值为38.840,n=3),μ=9.75~9.78。两者具有相近的Pb同位素组成且其壳源特征明显,表明它们的成矿金属来源相似,均来自上地壳,与赋矿沉积岩有关。综上,矿物学和同位素地球化学证据表明,天宝山矿床深部新发现铜矿与铅锌矿具有明显的同期共生关系和相似的成矿物质来源,是同一成矿热液体系不同阶段演化的产物。天宝山铜铅锌矿床与MVT矿床的成矿特征不同,暗示其成矿作用(环境)特殊,可能与矿床所处的地质背景有关,其成因认识对川滇黔接壤区同类型矿床深部找铜矿具有重要的指导意义。     

新疆“帕米尔式”铁矿床成因与成矿背景分析

帕米尔式"铁矿床是新疆西昆仑地区重要的磁铁矿床类型之一,其矿床地质特征、形成时代明显有别于典型的BIFs类型磁铁矿床。本文以塔什库尔干地区翁吉勒磁铁矿床和孜勒依磁铁矿床作为研究对象,通过研究其赋矿围岩和岩体的岩石地球化学特征、矿石矿相学特征、磁铁矿微量元素地球化学特征和原位Pb-Pb同位素特征,探讨了"帕米尔式"磁铁矿床的矿床成因和成矿背景。岩石地球化学研究表明翁吉勒黑云母二长花岗岩具有高SiO_2、Al_2O_3、K_2O和Na_2O。低MgO、CaO和TiO_2,而Na_2O/K_2O值变化范围很小。铝饱和指数为(1.44~1.51),显示其具有为弱过铝质岩石的特征,稀土总量富集,具有强的负Eu异常。在微量元素蛛网图上显示其富集大离子亲石元素(LILE),如K、Rb、Sr、Ba及轻稀土元素(LREE),亏损Nb、Ta,P、Ti等高场强元素。而黑云母石英片岩稀土含量亦较富集,具有中等强度的负Eu异常。低的Rb/Sr比,明显的Th、Zr、Hf、Nb、Ta,P、Ti负异常,明显的Ba正异常,显示岩石具有古大陆边缘环境的富铝沉积岩特征。翁吉勒黑云母二长花岗岩和布伦阔勒岩群黑云母石英片岩地球化学性质非常相似,表明翁吉勒黑云母二长花岗岩的形成与布伦阔勒岩群黑云母石英片岩的重熔有关。锆石LA ICP-MS定年结果表明翁吉勒黑云母二长花岗岩形成于15.0±0.3Ma和15.4±0.2Ma。磁铁矿LA ICP-MS微量元素地球化学特征表明翁吉勒铁矿床中的磁矿床中主要Si、Mn、Zn、Sn、Hf和Pb相对较高,其中Mn和Ga变化范围较大,而孜勒依铁矿床中的磁铁矿具有相对较高的亲石元素,如Mg、Al、Ti、V、Co、Ni、Ga和Sc等,其Mn和Zn含量较低且变化范围较大,其它元素变化范围均相对较窄。二者相比,翁吉勒铁矿床中的磁铁矿中微量元素变化范围相对较大,而孜勒依铁矿床中的磁铁矿变化范围较小。两个矿床的磁铁矿的原位Pb-Pb同位素存在明显的不同,两类岩石全岩Pb同位素与两个矿床中磁铁矿Pb-Pb同位素研究表明翁吉勒铁矿床中磁铁矿可能与黑云母二长花岗岩有关,为热液成因。综上所述,在塔什库尔干地区不仅存在与沉积作用有关的铁矿床,还可能存在一部分与年轻岩浆岩有关的热液型磁铁矿床。