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51.
Establishing a shallow water cover over tailings deposited in a designated storage facility is one option to limit oxygen diffusion and retard oxidation of sulfides which have the potential to form acid mine drainage (AMD). The Old Tailings Dam (OTD) located at the Savage River mine, western Tasmania contains 38 million tonnes of pyritic tailings deposited from 1967 to 1982, and is actively generating AMD. The OTD was constructed on a natural gradient, resulting in sub-aerial exposure of the southern area, with the northern area under a natural water cover. This physical contrast allowed for the examination of tailings mineralogy and geochemistry as a function of water cover depth across the OTD. Tailings samples (n = 144, depth: ≤ 1.5 m) were collected and subjected to a range of geochemical and mineralogical evaluations. Tailings from the southern and northern extents of the OTD showed similar AMD potential based on geochemical (NAG pH range: 2.1 to 4.2) and bulk mineralogical parameters, particularly at depth. However, sulfide alteration index (SAI) assessments highlighted the microscale contrast in oxidation. In the sub-aerial zone pyrite grains are moderately oxidized to a depth of 0.3 m (maximum SAI of 6/10), under both gravel fill and oxidized covers, with secondary minerals (e.g., ferrihydrite and goethite) developed along rims and fractures. Beneath this, mildly oxidized pyrite is seen in fresh tailings (SAI = 2.9/10 to 5.8/10). In the sub-aqueous zone, the degree of pyrite oxidation demonstrates a direct relationship with cover depth, with unoxidized, potentially reactive tailings identified from 2.5 m, directly beneath an organic-rich sediment layer (SAI = 0 to 1/10). These findings are broadly similar to other tailings storage facilities e.g., Fox Lake, Sherritt-Gordon ZnCu mine, Canada and Stekenjokk mine, Sweden where water covers up to 2 m have successfully reduced AMD. Whilst geotechnical properties of the OTD restrict the extension of the water cover, pyrite is enriched in cobalt (up to 2.6 wt%) indicating reprocessing of tailings as an alternative management option. Through adoption of an integrated mineralogical and geochemical characterization approach for tailings assessment robust management strategies after mine closure can be developed. 相似文献
52.
Chusi Li Edward M. Ripley Thomas Oberthür James D. MillerJr Gregory D. Joslin 《Mineralium Deposita》2008,43(1):97-110
Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide
zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction
between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical
and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal
alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of
magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion.
The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with
base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and
Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju
Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals
and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides,
antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental
studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides,
and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in
controlling the distribution of PGE in mineralized layered intrusions of this type. 相似文献
53.
四川天宝山铅锌矿床硫化物微量元素组成:LA-ICPMS研究 总被引:20,自引:11,他引:9
"川滇黔接壤铅锌矿集区"是我国西南大面积低温成矿域的重要组成部分,对于其中铅锌矿床是否属于MVT型矿床存在较大争议。本文以该矿集区中代表性矿床——四川天宝山矿床为例,通过LA-ICPMS原位元素分析,结合元素Mapping,以认识该矿床中闪锌矿和方铅矿微量元素组成特征及其赋存状态。研究表明,矿床中闪锌矿以富集Cd、Ge贫Fe、Mn、In、Sn、Co为特征,这些元素均以类质同象形式赋存于闪锌矿中,但含量变化范围较大,这可能与其成矿流体属于低温混合流体有关,这类盆地卤水流体在长期和长距离运移过程中,流经不同基底地层,活化出其中不同微量元素,因此成分变化较大,但以低温元素为主。此外,矿床中闪锌矿Ge和Cu呈现较好正相关关系,暗示其与Zn置换方式为:nC u~(2+)+Ge~(2+)(n+1)Zn~(2+),这可能是该矿床富集Ge的重要原因之一;矿床中方铅矿以富集Ag、Sb贫Bi为特征,含微量Cd和Tl,类质同象是这些元素主要赋存形式,其置换方式为(Ag)~(1+)+(Sb)~(3+)2Pb~(2+);矿床中Ge主要赋存于闪锌矿中,而方铅矿中不含Ge。总体上,本矿床硫化物微量元素组成与MVT型矿床基本一致,明显有别于喷流沉积型矿床、岩浆热液型矿床和远源夕卡岩型矿床,其成矿温度属于低温范围,成矿流体运移方向可能为深部→浅部。结合其矿床地质地球化学特征,本文认为天宝山铅锌矿床属于MVT型矿床,但其中闪锌矿中富集Cu,而方铅矿中富集Ag,可能暗示其形成具有一定特殊性。 相似文献
54.
Abundance and distribution of fatty acids within the walls of an active deep-sea sulfide chimney 总被引:3,自引:0,他引:3
Jiwei Li Huaiyang Zhou Xiaotong Peng Meiyan Fu Zhiqiang Chen Huiqiang Yao 《Journal of Sea Research》2011,65(3):333-339
Abundance and distribution of total fatty acids (TFAs) were examined along the physicochemical gradient within an active hydrothermal chimney collected from the Main Endeavour segment of Juan de Fuca Ridge. Approximately 27 fatty acids are identified with a chain-length ranging from C12 to C22. From the exterior to the interior of the chimney walls, the total concentrations of TFAs (∑ TFAs) show a trend of evident decrease. The observed compositions of TFAs are rich in bacterial biomarkers especially monounsaturated fatty acids (MUFAs) and minor branched and cyclopropyl FAs. On the basis of the species-specific FAs and bacterial 16SrRNA gene analysis (Li et al., unpublished data), sulfur-based metabolism appears to be the essential metabolic process in the chimney. Furthermore, the sulfur oxidizing bacteria (SOB) are identified as a basic component of microbial communities at the exterior of the hydrothermal chimney, and its proportion shows an inward decrease while the sulfate reducing bacteria (SRB) have an inverse distribution. 相似文献
55.
甘肃黑山铜镍硫化物含矿岩体的地质特征及橄榄石成因探讨 总被引:5,自引:0,他引:5
黑山铜镍硫化物含矿岩体位于中亚造山带南缘北山褶皱带东部,对该岩体的研究有助于正确理解造山带型铜镍硫化物的成矿作用。详细的野外基础地质特征表明黑山矿区仅出露单一的新元古代青白口系地层,无寒武纪地层出露。黑山含矿岩体由早期的方辉橄榄岩、二辉橄榄岩和橄榄辉长苏长岩,以及稍晚期的辉长岩脉组成。黑山岩体位于黑山背斜南翼,其初始产状应为一水平或近水平的岩床状岩体,因后期褶皱作用,岩体发生了倾斜形成现今的产状。黑山岩体中橄榄石Fo值为80.5~87.0,其Ni含量为1070×10-6~3461×10-6。借助"MELTS"软件,我们进一步厘定了黑山母岩浆为高镁玄武岩浆 (12.81% MgO, 10.84% FeO, 430×10-6 Ni)。研究表明,黑山橄榄石的主要控制因素为:1)母岩浆的成分;2)后续新鲜岩浆的补充混合作用;3)硫化物熔离作用;4)晶间硅酸盐熔浆作用;5)橄榄石与硫化物之间发生的Fe-Ni交换。模拟计算表明,硫化物熔离与橄榄石结晶几乎同时发生,橄榄石与硫化物的最小质量比约为20:1。1号矿体及矿化体的橄榄石比4号矿体更富Mg和Ni,并且还呈现非常好的负相关关系,表明这些橄榄石与硫化物发生了不同程度的Fe-Ni交换,而与其发生Fe-Ni交换的硫化物更富Ni以及共生的岩浆更为原始。这很可能是因为黑山岩体形成于开放的岩浆通道系统,早期融离的硫化物与后续的新鲜的硫不饱和岩浆发生反应,使得该类硫化物含量减少但硫化物中的金属元素含量增高从而形成1号矿体及矿化体。 相似文献
56.
57.
新疆东部天宇镁铁-超镁铁杂岩体位于中天山地块的北部边缘,北侧为塔里木板块前缘活动带-沙泉子深大断裂。该杂岩体由辉长岩、辉石岩、橄辉岩、辉橄岩和橄榄岩组成,橄辉岩、辉橄岩和橄榄岩是主要的Cu、Ni矿赋矿岩相。同位素稀释法测得的铂族元素(PGE)结果显示天宇镁铁-超镁铁岩和铜镍矿石中∑PGE含量低(0.106~57.369ppb),为原始地幔的0.01~1倍。随岩石基性程度的升高,铂族元素含量略有增高。不同矿化程度的矿石大致表现出随硫化物含量的增多,∑PGE含量增高的趋势。岩石和矿石标准化曲线均表现出正斜率,Pt都为负异常或无异常(TY602-29除外)。根据岩浆和硫化物中Ni和S含量计算,得出天宇铜镍硫化物矿床R值为348~3807,该R值范围可以形成铜镍矿床,但无法形成铂族元素矿床。Pd/Ir-Cu/Ni的投图显示原始岩浆主要为高Mg玄武岩。矿石中100%硫化物PGE含量远低于地幔5%部分熔融形成的岩浆(R=1000时)中PGE含量,与高Mg玄武岩10%的熔融程度不符。通过模拟计算,天宇矿区存在同源但R值不同的两批岩浆。 相似文献
58.
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
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
59.
Sonja Aulbach Steven B. Shirey Thomas Stachel Steven Creighton Karlis Muehlenbachs Jeff W. Harris 《Contributions to Mineralogy and Petrology》2009,157(4):525-540
Sulfide inclusions in diamonds from the 90-Ma Jagersfontein kimberlite, intruded into the southern margin of the Kaapvaal
Craton, were analyzed for their Re–Os isotope systematics to constrain the ages and petrogenesis of their host diamonds. The
latter have δ13C ranging between −3.5 and −9.8‰ and nitrogen aggregation states (from pure Type IaA up to 51% total N as B centers) corresponding
to time/temperature history deep within the subcontinental lithospheric mantle. Most sulfides are Ni-poor ([Ni + Co]/Fe = 0.05–0.25
for 15 of 17 inclusions), have elevated Cu/[Fe + Ni + Co] ratios (0.02–0.36) and elemental Re–Os ratios between 0.5 and 46
(12 of 14 inclusions) typical of eclogitic to more pyroxenitic mantle sources. Re–Os isotope systematics indicate two generations
of diamonds: (1) those on a 1.7 Ga age array with initial 187Os/188Os (187Os/188Osi) of 0.46 ± 0.07 and (2) those on a 1.1 Ga array with 187Os/188Osi of 0.30 ± 0.11. The radiogenic initial Os isotopic composition for both generations of diamond suggests that components with
high time-integrated Re–Os are involved, potentially by remobilization of ancient subducted oceanic crust and hybridization
of peridotite. A single sulfide with higher Os and Ni content but significantly lower 187Os/188Os hosted in a diamond with less aggregated N may represent part of a late generation of peridotitic diamonds. The paucity
of peridotitic sulfide inclusions in diamonds from Jagersfontein and other kimberlites from the Kaapvaal craton contrasts
with an overall high relative abundance of diamonds with peridotitic silicate inclusions. This may relate to extreme depletion
and sulfur exhaustion during formation of the Kaapvaal cratonic root, with the consequence that in peridotites, sulfide-included
diamonds could only form during later re-introduction of sulfur. 相似文献
60.
Located adjacent to the Banded Gneissic Complex, Rampura–Agucha is the only sulfide ore deposit discovered to date within
the Precambrian basement gneisses of Rajasthan. The massive Zn–(Pb) sulfide orebody occurs within graphite–biotite–sillimanite
schist along with garnet–biotite–sillimanite gneiss, calc–silicate gneisses, amphibolites, and garnet-bearing leucosomes.
Plagioclase–hornblende thermometry in amphibolites yielded a peak metamorphic temperature of 720–780°C, whereas temperatures
obtained from Fe–Mg exchange between garnet and biotite (580–610°C) in the pelites correspond to postpeak resetting. Thermodynamic
considerations of pertinent silicate equilibria, coupled with sphalerite geobarometry, furnished part of a clockwise P–T–t path with peak P–T of ∼6.2 kbar and 780°C, attained during granulite grade metamorphism of the major Zn-rich stratiform sedimentary exhalative
deposits orebody and its host rocks. Arsenopyrite composition in the metamorphosed ore yielded a temperature [and log f(S
2)] range of 352°C (−8.2) to 490°C (−4.64), thus indicating its retrograde nature. Contrary to earlier research on the retrogressed
nature of graphite, Raman spectroscopic studies on graphite in the metamorphosed ore reveal variable degree of preservation
of prograde graphite crystals (490 ± 43°C with a maximum at 593°C). The main orebody is mineralogically simple (sphalerite,
pyrite, pyrrhotite, arsenopyrite, galena), deformed and metamorphosed while the Pb–Ag-rich sulfosalt-bearing veins and pods
that are irregularly distributed within the hanging wall calc–silicate gneisses show no evidence of deformation and metamorphism.
The sulfosalt minerals identified include freibergite, boulangerite, pyrargyrite, stephanite, diaphorite, Mn–jamesonite, Cu-free
meneghinite, and semseyite; the last three are reported from Agucha for the first time. Stability relations of Cu-free meneghinite
and semseyite in the Pb–Ag-rich ores constrain temperatures at >550°C and <300°C, respectively. Features such as (1) low galena–sphalerite
interfacial angles, (2) presence of multiphase sulfide–sulfosalt inclusions, (3) microcracks filled with galena (±pyrargyrite)
without any hydrothermal alteration, and (4) high contents of Zn, Ag (and Sb) in galena, indicate partial melting in the PbS–Fe0.96S–ZnS–(1% Ag2S ± CuFeS2) system, which was critical for metamorphic remobilization of the Rampura–Agucha deposit. 相似文献