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1.
利用显微镜和碳同位素分析法对自河南西峡盆地晚白垩世的１６枚恐龙蛋化石进行了研究。在显微镜下观察到恐龙蛋化石壳由原生碳酸盐矿物和次生碳酸盐矿物两部分组成。利用图像分析法得到了两者所占的比例分别为６０．５％和３９．５％。恐龙蛋内充填的次生碳酸盐矿物的δ＾１３Ｃ值在－５．６３‰￣－５．６８‰之间,平均为－５．６５‰。恐龙蛋化石壳的δ＾１３Ｃ同位素值在－５．８８‰￣－７．７９‰之间。经计算,获得了恐龙蛋壳 相似文献
2.
五台山区太古宙铁建造型金矿成矿流体性质和成因 总被引：1，自引：1，他引：0
五台山区铁建造金矿经历初生成矿作用和叠加成矿作用。初生成矿作用形成于变质峰期一,与区域变质作用有关。矿石富含水溶液包裹２体。包裹体均一温度１７１～２５５℃,压力０．１２～０．３１ＧＰａ。流体成分模式Ａｕ－Ｈ２Ｓ＋ＮａＣｌ－ＣＯ２－Ｈ２Ｏ。氢氧同位素具变质水和雨水双重笥,本主要来源于变质热液,受雨水混合。叠加成矿作用可能受岩浆活动影响,矿石富含ＣＯ２包裹体,均一温度３０６～３８５℃,压力０．６～１０ 相似文献
3.
吉林省大黑山条垒南段构造演化与成矿作用 总被引：4，自引：0，他引：4
作者将本区的构造演化划分成三个阶段，即海西－印支期、燕山期和四川期。海西－印支期应力作用以近ＳＮ向挤压为主，成矿作用为Ｐｂ－Ｚｎ－Ｃｕ多金属硫化物矿床；燕山期应力作用以ＮＷ－ＳＥ向挤压为主，成矿作用为Ｐｂ－Ｚｎ－Ａｇ为主，平均差应力值１２０．５ＭＰａ；四川期应力作用呈ＮＮＥ－ＳＳＷ向，成矿作用以Ａｇ－Ａｕ为主，平均差应力值１０１．４ＭＰａ。 相似文献
4.
粘土矿物以其特殊的性质，在层间渗入成矿作用中吸附、迁移和富集铀元素。在这一成矿过程中，粘土矿物同时也发生着次生演化。层间渗入流体的性质决定了后生铀矿化的富集程度及次生粘土矿物的类型。不同的次生粘土矿物组合可能预示着后生铀矿床不同的规模。 相似文献
5.
川西北马脑壳金矿床成矿流体地球化学特征与性质 总被引：6，自引：2，他引：6
马脑壳金矿床是20世纪80年代末期在川西北地区发现的一大型微细浸染型矿床，它赋存于中三叠统扎尕山组地层之中，矿体产出受北西向次级断裂构造的控制。矿床的形成经历了成矿前金初步富集、热液成矿作用－原生矿石形成及麦生氧化－金次生再富集第三期主要成矿作用过程。热液金成矿作用可进一步划分为（1）黄铁矿－毒砂－石英；（Ⅱ）石英－（白钨矿）－辉锑矿；（Ⅲ）石英－雄（雌）黄及（Ⅳ）石英－方解石等4个矿化阶段，其中Ⅰ、Ⅱ阶段为金的主要沉淀富成矿阶段。系统的流体包裹体研究表明，成矿前（Ⅰ′）及热液成矿Ⅰ－Ⅳ阶段石英中共发育液相、纯液相、含CO2三相、富CO2相及含有机质等5种类型的原生流体包裹体。测温结果显示，Ⅰ′及Ⅰ-Ⅳ类石英中液相及含CO2三相包裹体均一温度为120－300℃，热液盐度为0．5％－11．0％；包裹体成分分析结果表明，热液阳离子以Na^ 、K^ 及Ca^2 为主，阴离子主要为HCO3^-及CI^-，气相组分除H2O外，尚含一定量的CO2及CH4等；热液pH值为6．7－72，Eh值为－0．85～0.69eV；成矿热液总体属中低温、低盐度、近中性和弱还原性的含有机质Na^ -K^ -Ca^2 -HCO3^--CI^-体系类型。H、O同位素研究结果表明，成矿前热液主要来源于变质水和地层建造水，成矿期以来大气降水不断 混入并逐步占据优势。主成矿阶段成矿热液发生过明显的注体混合相分离作用，对金的沉淀富集成矿起了重要作用。 相似文献
6.
云南元谋盆地干润变性土中次生方解石特征及形成 总被引：1，自引：0，他引：1
土壤新生体对于研究区域环境变化、营养元素释放以及次生成矿作用具有重要意义。利用化学分析、X射线衍射、偏光显微镜和扫描电子显微镜等探讨云南省元谋盆地干润变性土钙质结核中的次生方解石的特征和形成过程。结果表明，钙质结核中次生方解石含量高，晶形完整；钙质结核以及次生方解石形成既取决于气候，也与微地形有关。次生方解石的形成过程及特征反映了自全新世以来元谋盆地主要处于干热气候环境中。 相似文献
7.
8.
污染指数法用于碳酸盐型尾矿(指富含碳酸盐的金属硫化物尾矿)重金属污染评价存在局限性。通过研究湖南黄沙坪铅锌矿尾矿中Zn、Cd、Pb、Cu及As等元素赋存状态(包括尾矿铅垂剖面结构、元素总量及其水溶态分量的分布和影响因素以及次生胶结物纤铁矿与元素结合作用等),结合元素迁移活性(水溶取率)和污染指数分析,得出如下结论:1该尾矿发育层(带)状结构,即浅表胶结硬化层(中褐色,氧化/酸化)→中部弱胶结层(黄褐色,次氧化)→深部尾砂层(橄榄灰-绿灰色,弱/未氧化),重金属元素在尾矿中浅部的胶结层中富集;2纤铁矿为主要次生胶结物,纤铁矿与元素结合作用的差异性影响尾矿中元素的稳定性/迁移活性;3尾矿中Zn、Cd的迁移活性和污染指数均较高,是主要的污染因子,应重点防控;As的污染指数虽高,但因其迁移活性较低,仍属次要污染因子;Pb、Cu的迁移活性及污染指数均较低,对环境影响可能较小。采用污染指数与元素赋存状态分析相结合的方法,对(黄沙坪)碳酸盐型尾矿的重金属污染危险进行综合评价,可避免污染指数法的局限性。 相似文献
9.
甘孜－理塘断裂带北段主要金矿类型及地质特征 总被引：7，自引：0，他引：7
根据金矿的产出地质环境和成矿作用方式，将甘孜－理塘断裂带北段金矿划分为５类，并从矿区地质特征，矿床地质特征及成矿作用等方面作了较为系统阐述． 相似文献
10.
焦家式金矿水－岩交换作用─—成矿流体氢氧同位素组成研究 总被引：7，自引：0，他引：7
焦家式金矿位于胶东半岛西北部，矿体赋存于花岗片麻岩－花岗闪长岩类岩石断裂带内，呈破碎黄铁绢英岩化浸染状矿石。矿体中均伴有富含金的成矿前、后中基性脉岩。成矿作用包括乳白色块状黄铁矿石英和（或）伟晶石英脉阶段、含金硫化物石英阶段和方解石石英阶段。三个阶段石英δ￣（１２）Ｏ值平均为１２．４‰、１３．２‰和１４．４‰。计算的石英δ￣（１８）Ｏ＿（Ｈ＿２Ｏ）值平均分别为４．７‰、３．５‰和３．５‰。三个阶段石英流体包裹体水δＤ＿（Ｈ＿２Ｏ）值平均分别为－７３‰、－８０‰和－９２‰。经反演计算，提出成矿流体是中生代大气降水（δ￣（１８）Ｏ＝－１５．５‰，δＤ＝－１１５‰）与５ｋｍ以下深部中基性岩在３５０～４００℃时，有效Ｗ／Ｒ比值从０．０１至０．０５之间交换作用形成。 相似文献
11.
Undrained Strength of Deposited Mine Tailings Beds: Effect of Water Content, Effective Stress and Time of Consolidation 总被引：1，自引：0，他引：1
An understanding of the geotechnical behaviour of mine tailings is imperative when evaluating the stability and erosional
resistance of sedimented tailings beds; as well as for the design and long-term management of tailings disposal facilities.
Laboratory testing was conducted on mine tailings beds of various ages and thicknesses, deposited from concentrated slurries.
Measured index properties allowed classifying the tailings as a coarse grained and non-cohesive material. The results obtained
from the performed sedimentation experiments showed that the primary consolidation of the tailings beds was complete in approximately
1 h and negligible volume changes occurred in the beds during secondary compression. The undrained shear strength of the tailings
beds was measured using an automated fall cone device at a depth interval of 1 cm and a profile of the shear strength variation
with depth was obtained. At each tested surface, moisture content specimens were taken to determine the moisture content profile
of the tested tailings beds. The undrained shear strength of the beds varied between 0.008 and 0.975 kPa for effective stresses
below 1.19 kPa and increased with depth. Correspondingly, the moisture content decreased with depth and varied between 17
and 27%. The factor controlling the undrained shear strength of the tested beds was the vertical effective stress, with the
water content also having some secondary effect. The correlation between the undrained shear strength and the vertical effective
stress was expressed with a second order polynomial function. Consolidation time did not appear to influence the observed
shear strength. 相似文献
12.
Mobilization and attenuation of heavy metals within a nickel mine tailings impoundment near Sudbury, Ontario, Canada 总被引：1，自引：0，他引：1
R. G. McGregor D. W. Blowes J. L. Jambor W. D. Robertson 《Environmental Geology》1998,36(3-4):305-319
The oxidation and the subsequent dissolution of sulfide minerals within the Copper Cliff tailings area have led to the release
of heavy metals such as Fe, Ni, and Co to the tailings pore water. Dissolved concentrations in excess of 10 g/l Fe and 2.2
g/l Ni have been detected within the shallow pore water of the tailings, with increasing depth these concentrations decrease
to or near analytical detection limits. Geochemical modelling of the pore-water chemistry suggests that pH-buffering reactions
are occurring within the shallow oxidized zones, and that secondary phases are precipitating at or near the underlying hardpan
and transition zones. Mineralogical study of the tailings confirmed the presence of goethite, jarosite, gypsum, native sulfur,
and a vermiculite-type clay mineral. Goethite, jarosite, and native sulfur form alteration rims and pseudo-morphs of the sulfide
minerals. Interstitial cements, composed of goethite, jarosite, and gypsum, locally bind the tailings particles, forming hardpan
layers. Microprobe analyses of the goethite indicate that it contains up to 0.6 weight % Ni, suggesting that the goethite
is a repository for Ni. Other sinks detected for heavy metals include jarosite and a vemiculite-type clay mineral which locally
contains up to 1.6 weight % Ni. To estimate the mass and distribution of heavy metals associated with the secondary phases
within the shallow tailings, a series of chemical extractions was completed. The experimental design permitted four fractions
of the tailings to be evaluated independently. These four fractions consisted of a water-soluble, an acid-leachable, and a
reducible fraction, as well as the whole-rock total. Twenty-five percent of the total mass of heavy metals was removed in
the acid-leaching experiments, and 100% of the same components were removed in the reduction experiments. The data suggest
that precipitation/coprecipitation reactions are providing an effective sink for most of the heavy metals released by sulfide
mineral oxidation. In light of these results, potential decommissioning strategies should be evaluated with the recognition
that changing the geochemical conditions may alter the stability of the secondary phases within the shallow tailings.
Received: 9 April 1997 · Accepted: 21 July 1997 相似文献
13.
《Applied Geochemistry》2005,20(3):661-667
This paper describes the geochemical testing of mine tailings sourced from the Black Swan Ni Mine located near Kalgoorlie, Western Australia. Acid–base accounting was used to provide an indication of the acid generating capacity of two kinds of mining tailings: disseminated-ore tailings from the Cygnet Tailings Dam Storage Facility (CTDSF) and massive-ore tailings from the Silver Swan Tailings Dam Storage Facility (SSTDSF). All of the tailings in SSTDSF have acid generating potential which is consistent with previous research reports. New findings in this paper reveal that approximately 16% of the tailings in CTDSF have the potential to be acid generating. In contrast, previous reports state that the disseminated-ore tailings are classified as non-acid forming. Most of the potential acid generating tailings in the CTDSF are found in the upper-middle sections of the tailings profile, but some are located at the bottom of the tailings dam. The upper-middle section of the tailings is oxidized because these tailings have interacted with atmospheric O2 and rain and surface water. Oxidation of the bottom tailings in the CTDSF may be due to infiltration of ground water into hidden fractures under the east bank of CTDSF, which caused these tailings to oxidize under closed and reduced conditions.The acid drainage in the tailings dam storage facility was observed 3 a, after the development of the Black Swan Nickel project. This delayed production of acid drainage was likely due to the slow rates of acid neutralization provided by alteration gouge minerals such as Mg/Fe-carbonates (magnesite–siderite series) associated with the Ni ores. The acid drainage leaking from the tailings dams has contaminated neighboring ground water via increased acidity and heavy metals.Because of the potential acid generation in some of the disseminated ore tailings, it is inadvisable to use disseminated ore tailings as cover materials in the storage facility to isolate the underlying potentially-acid-forming tailings from O2 and water, as proposed by previous research reports. 相似文献
14.
The oxidation and subsequent dissolution of sulfide minerals within mine tailings impoundments releases H+, Fe(II), SO4 and trace elements to the tailings pore water. Subsequent pH-buffering and hydrolysis reactions result in the precipitation of secondary phases such as gypsum, goethite and jarosite. In areas of intense precipitation, cemented layers or “hardpans” often form within the shallow tailings. Three cemented layers within pyrrhotite-bearing mine tailings at the Fault Lake, Nickel Rim and East Mine impoundments located near Sudbury, Canada, were examined. The location of the three cemented layers within the tailings stratigraphy varies as does their location relative to the water table. The morphology, mineralogy and chemical composition of the cemented layers also vary between sites. The bulk density within the three cemented layers all showed an increase relative to the surrounding uncemented tailings ranging from 9% to 29%. The porosity of each cemented layer decreased relative to the surrounding uncemented tailings ranging from an 8% to 18% decrease. The cemented layers also showed relative enrichment of total sulfur, carbon and trace elements relative to the surrounding uncemented tailings. Arsenic concentrations showed an enrichment in the cemented layers of up to 132%, Cd up to 99%, Co up to 84%, Cu up to 144%, Ni up to 693% and Zn up to 145% relative to the surrounding uncemented tailings. All the cemented layers studied show an evolution of the secondary phases with time from a gypsum–jarosite-based cement to a goethite-rich cement. The formation of these layers could potentially have a significant effect on the environmental impacts of sulfide-bearing mine waste. 相似文献
15.
湘西金矿尾矿—水相互作用：1．环境地球化学效应 总被引：8，自引：2，他引：8
湘西金矿在生产过程中产生了大量的尾矿。该区尾矿－水相互作用强烈，并引起了尾矿中重金属元素的释放、迁移和对水体－土壤、蔬菜等表生环境的重金属污染。污染程度较大的元素均为Au、Sb、As、Cd、Hg、W等，与尾矿中元素的富集特征相一致。尾矿中重金属元素的水迁移能力由大到小顺序为Au、Cd、W、Sb、Pb、As、Zn、Cu。元素的生物吸收系数由大至小顺序为Cd、Au、Zn、Hg、Sb、Cu、Pb、As、W。植物中金属元素浓度主要受土壤中的浓度、植物种类和吸收的影响。 相似文献
16.
Field and laboratory studies of the sulphide-bearing tailings at Laver, northern Sweden, show that the present release of
metals from the tailings is low, especially with regard to Cu. A large part of the Cu released by sulphide oxidation is enriched
in a distinct zone just below the oxidation front. The enrichment zone occurs almost all over the tailings area except in
areas with a shallow groundwater table. The Cu enrichment is caused by formation of covellite and adsorption onto mineral
surfaces. The transport of Zn, Co, Cd, Ni and S seems to be controlled mainly by adsorption. No secondary zone or secondary
minerals containing these metals have been found. Just below the groundwater table, metals are released into solution when
the enrichment zone reaches the groundwater due to the low pH. An increased release of metals, especially Cu, can be expected
in the future, since the enrichment zone is moving towards the groundwater table.
Received: 4 December 1997 · Accepted: 17 December 1998 相似文献
17.
《Applied Geochemistry》1999,14(6):747-759
A study of O2 penetration and pore water geochemistry of the flooded tailings at Stekenjokk has been performed. The results show that there is a diffusion of elements from the tailings pore water to the overlying water. The presence of elements such as Ca, Mg, S, Si, Ba and Sr are likely the result of diffusion of older process water trapped in the tailings. Oxygen concentrations in the tailings measured with microelectrodes show that there is O2 available down to 16 to 17 mm depth in the tailings. Pore water analyses show that there are subsurface maxima for the elements Cu, Zn, Ni, Co and Cd at depths of 0.25 to 2.75 cm. The highest concentrations of almost all elements were found where previously oxidised material was deposited before the flooding. Lower pH is measured in the uppermost part of the tailings compared with the pond water and the tailings pore water at depth. Oxidation of sulphides in the uppermost part of the tailings is probably occurring. A decrease in oxidation rate can be expected in the future due to deposition of organic material at the tailings surface. Flooding seems to be an efficient remediation method at Stekenjokk. 相似文献
18.
A minesoil has developed over 5 years oxidative exposure on sulphide concentrate tailings (ca. 1 wt.% As) at the Macraes mesothermal gold mine, New Zealand. The minesoil has a dry crust which has formed due to evaporative drying. This dry crust is enriched in arsenic (ca. 5 wt.% As) as scorodite (FeAsO4·2H2O) because of upward mobility of dissolved arsenic during drying. Similar enrichment of arsenic has occurred along the walls of desiccation cracks which extend over 1 m into the minesoil. Capping of the tailings and minesoil with wet tailings (pH=8) results in dissolution of scorodite and remobilization of arsenic on the millimetre scale. Experimental capping of the minesoil with wet calcium carbonate remobilized some arsenic from scorodite on the centimetre scale, but much original arsenic enrichment was preserved after 400 days. A layer of gypsum (CaSO4·2H2O) and iron oxyhydroxide cementation developed at the interface between the minesoil and the experimental calcium carbonate cap, restricting water flow. This layer was ca. 1 mm thick after 400 days. Theoretical comparison between advection and diffusion in the minesoil suggests that diffusion is an important mechanism for chemical mobility on the 1–50-year time scale. However, advection can be important in secondary porosity of the dry crust of the minesoil and water penetrates this zone at a rate of 1.5 mm/day. 相似文献
19.
The pore-water geochemistry and mineralogy of tailings derived from a granitic tungsten deposit were characterized by collecting pore-water samples at discrete depth intervals throughout the tailings for the analysis of major and minor element concentrations. Mineralogical samples from the oxidation zone were analyzed by X-ray diffraction, scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM/EDS), electron microprobe (EMP) combined with wavelength dispersive X-ray spectroscopy (WDS), and transmission electron microscopy (TEM). The oxidation of sulfide minerals in the near-surface tailings leads to a decrease in pore-water pH and elevated SO4, As, and metal concentrations. The unusual mineralogy of this deposit, compared with that of commonly studied base-metal and gold deposits, results in several unique geochemical characteristics. The dissolution of fluorite releases F into the pore water; the F forms strong complexes with Al and enhances the dissolution of aluminosilicate minerals within the oxidation zone. As a result, high Al concentrations (up to 151.7 mg/L) are detected in the near-neutral pore water in the oxidation zone. The combined dissolution of aluminosilicates and carbonate minerals maintains the pH near 10 in the pore water at depth. Elevated concentrations of W (up to 7.1 mg/L) are detected in the pore water throughout the tailings, likely as a result of the dissolution of wolframite. Consistent with geochemical model calculations, results from SEM/EDS, EMP/WDS and TEM/EDS analyses indicate that secondary minerals, which occur as orange-brown coatings on grains of primary-minerals, are Fe oxyhydroxides. Examples of these secondary minerals display a fibrous habit at high resolution in the TEM. One of these minerals, which contains substantial amounts of Al, As, and Si as impurities, was identified by selected-area electron diffraction (SAED) analyses to be goethite. Another mineral contains relatively high amounts of Si, Pb, Bi, and As, and SAED analyses suggest that the mineral is two-line ferrihydrite. 相似文献
20.
《Applied Geochemistry》1999,14(4):485-498
Fine grained (ca. 15 μm), arsenopyrite-bearing mine tailings have been exposed to drying and oxidation for 4 a pending relocation. The tailings are still partly covered by a pond of decanted pore waters. The water table in drying tailings has lowered by 1–3 m and desiccation cracks up to 2 cm wide have formed on the 1 m scale, extending through the unsaturated zone. Tailings in the unsaturated zone have similar pore water contents to saturated tailings: typically 16–32 wt% water. Saturated tailings retain alkaline pH (ca. 10) from the mine cyanidation plant, but pH lowers progressively towards ca. 7 near the surface, or near desiccation cracks, in the unsaturated zone. The redox state of the tailings changes in parallel with pH, with an empirical relationship: Eh(mV)=−55 pH+290. Water in the remnant decant pond reflects this relationship also. Unsaturated tailings have variable but low permeabilities, typically 10−3 to 10−4 m/day, and more permeable horizons have allowed incursion of oxygenated air and/or rain water from desiccation cracks. Sulphide grains in all tailings examined are unaltered. Sulphides and solutions in the tailings are out of thermodynamic equilibrium predicted from the redox–pH conditions, due to kinetic constraints. Incursion of rain water locally facilitates deposition from pore waters of insoluble Fe oxide and arsenate minerals, thus fixing As in the dry unsaturated tailings. 相似文献