Biogeochemical Prospecting of Sulphide Minerals in Winder Valley, Balochistan, Pakistan

Abstract: The Mor Range is mountainous terrain in southern Balochistan dominantly occupied by exposures of rocks of the Ferozabad Group which is comprised of Lower‐Middle Jurassic carbonates and siliciclastics. This group contains syngenetic and epigenetic Zn–Pb–Ba mineralization classified as Stratiform Sediment‐Hosted (SSH) and Mississippi Valley Type (MVT) deposits. Three important flora of the Saharo–Sindian, phytogeographical region of Pakistan, namely Tamarix aphyl–la, Salvadora oleoides and Acacia arabica have been studied as a mineralization prospecting tool. Samples of these species were collected from Winder Valley adjoining the Mor Range to prospect for new areas of mineralization, besides the known sulphide deposits. This study revealed the Draber, Thorar, Raj, Mithi and Kanrach localities as new prospect. Quantitative estimation of biophile elements (Zn–Cu–Pb) from the three species was made. A number of new Zn, Cu and Pb anomalies were distinguished in the area. The variation in the constituents of these species from different localities possibly varies with nature and distance from bedrock, mobility, climate, average abundance in the plant ash and exclusion mechanism of the flora. Acacia arabica with deep penetrating roots shows the best results and could be used to delineate new horizons of mineralization. In these species Zn and Cu are relatively concentrated whereas Pb shows limited enrichment. Lead therefore is the element best suited for pinpointing the mineralization owing to its relatively less mobile character. Relationships among Zn–Cu–Pb have been established using scattergrams and triangular variation diagram, which also demonstrate their genetic affiliation. Statistical analyses, such as determination of mean, mode, median, standard deviation, and coefficient of correlation, were also made to improve the raw geochemical data. These biogeochemical methods appear to be suitable in arid climate of Balochistan, if proper attention is paid to species selection.     

The mineralized veins and the impact of old mine workings on the environment at Segura, central Portugal

At Segura, granitic pegmatite veins with cassiterite and lepidolite, hydrothermal Sn–W quartz veins and Ba–Pb–Zn quartz veins intruded the Cambrian schist–metagraywacke complex and Hercynian granites. Cassiterite from Sn–W quartz veins is richer in Ti and poorer in Nb and Nb+Ta than cassiterite from granitic pegmatite. Wolframite from Sn–W quartz veins is enriched in ferberite component. The Sn–W quartz veins contain pyrrhotite, arsenopyrite, sphalerite, chalcopyrite, stannite, matildite and schapbachite and the Ba–Pb–Zn quartz veins have cobaltite, pyrite, sphalerite, chalcopyrite, galena and barite, which were analyzed by electron microprobe. The presently abandoned mining area was exploited for Sn, W, Ba and Pb until 1953. Stream sediments and soils have higher concentrations of metals than parent granites and schists. Sn, W, B, As and Cu anomalies found in stream sediments and soils are associated with Sn–W quartz veins, while Ba, Pb and Zn anomalies in stream sediments and soils are related to Ba–Pb–Zn quartz veins. Sn, W, B, As, Cu, Ba, Pb and Zn anomalies in stream sediments and soils are also related to the respective old mining activities, which increased the mobility of trace metals from mineralized veins to soils, stream sediments and waters. Stream sediments and soils are sinks of trace elements, which depend on their contents in mineralized veins and weathering processes, but Sn, W and B depend mainly on a mechanic process. Soils must not be used for agriculture and human residence due to their Sn, B, As and Ba contents. Waters associated with mineralized veins were analyzed by flame atomic absorption spectroscopy (FAAS) and ICP-AES have high As, Fe and Mn and should not be used for human consumption and agriculture activities. The highest As values in waters were all related to Sn–W quartz veins and the highest Fe and Mn values were associated with the Ba–Pb–Zn quartz veins. No significant acid drainage was found associated with the old mine workings.     

The environmental impact of Aguilar mine on the heavy metal concentrations of the Yacoraite River,Jujuy Province,NW Argentina

The Yacoraite River and its tributaries run down the eastern slope of the Aguilar Range. It is one of the tributaries of the Rio Grande, located in Quebrada de Humahuaca, a UNESCO World Heritage site. The Aguilar underground mine (Pb–Ag–Zn) is located in the upper reaches of the Yacoraite River drainage basin. The aim of this work is to characterize the presence of heavy metals in water and sediments of the Yacoraite River and to identify their sources. The analysis shows the seasonal variation of heavy metals concentration in water and their relation with the World Health Organization (WHO) limits established for human consumption. The Yacoraite basin is naturally anomalous in some metals and some elements, such as As which is controlled by the chemical composition of regional lithology. During the wet season, Al, Co, Mo and Pb concentrations in water samples are higher than during the dry season; in addition, these metals are also higher than WHO limit values. High enrichment factors for Ba, Mo, Pb, Zn and Cd were found in Casa Grande stream, indicating the direct influence of the mining activities. Cd, Pb and Zn are present in the Aguilar ore minerals, such as sphalerite and galena. Sediments collected during the dry season show a drastic increase in the concentration of As, Pb, Ba, Zn, Cd and Mn. The Müller geo-accumulation index in Casa Grande indicates that it is a highly polluted stream. The concentrations of As, Pb, Ba, Zn, Cd are also high in Yacoraite River: Security Quality Guidelines indicates toxicity. A decrease in enrichment factors and geo-accumulation indices observed in sediments indicates the occurrence of precipitation/adsorption processes in the river to restore the equilibrium composition. Strict environmental controls in Aguilar Mine are necessary to avoid the uncontrolled input of toxic metals in Casa Grande stream and Yacoraite River.     

Stratigraphy and base metal mineralization in the Otavi Mountain Land, Northern Namibia—a review and regional interpretation

Sediment-hosted base metal sulfide deposits in the Otavi Mountain Land occur in most stratigraphic units of the Neoproterozoic Damara Supergroup, including the basal Nosib Group, the middle Otavi Group and the uppermost Mulden Group. Deposits like Tsumeb (Pb–Cu–Zn–Ge), Kombat (Cu–Pb–Zn), Berg Aukas (Zn–Pb–V), Abenab West (Pb–Zn–V) all occur in Otavi Group dolostones, whereas siliciclastic and metavolcanic rocks host Cu–(Ag) or Cu–(Au) mineralization, respectively. The Tsumeb deposit appears to have been concentrated after the peak of the Damara orogeny at around 530 Ma as indicated by radiometric age data.Volcanic hosted Cu–(Au) deposits (Neuwerk and Askevold) in the Askevold Formation may be related to ore forming processes during continental rifting around 746 Ma. The timing of carbonate-hosted Pb–Zn deposits in the Abenab Subgroup at Berg Aukas and Abenab is not well constrained, but the stable (S, O, C) and Pb isotope as well as the ore fluid characteristics are similar to the Tsumeb-type ores. Regional scale ore fluid migration typical of MVT deposits is indicated by the presence of Pb–Zn occurrences over 2500 km² within stratabound breccias of the Elandshoek Formation. Mulden Group siliciclastic rocks host the relatively young stratiform Cu–(Ag) Tschudi resource, which is comparable to Copperbelt-type sulfide ores.     

闽东北地区金银矿床的水系沉积物地球化学特征

闽东北地区位于政和—大埔断裂带东侧。在晚侏罗世—早白垩世,该地区经历了十分强烈的火山活动,形成了分布广泛、厚度巨大的陆相火山沉积岩系,其下伏基底地层中的迪口组与福建省金矿或矿化关系极为密切,是福建省重要的含金矿源层,有较好的成矿条件。水系沉积物异常重现性试验及元素的表生迁移研究表明,不同采样批次、不同季节、不同年份在相同采样介质和采样点获得的主要成矿元素异常重现性较好。与全国水系沉积物元素平均含量相比,Au、Ag、Pb、Zn异常较明显。水系沉积物元素异常统计揭示,Au、Ag、As、Sb的成矿能力评价最高。这种元素异常组合表明,与火山岩有关的金矿是本区最有利的成矿矿种,并在闽东北地区经钻探验证,取得了良好的找矿效果。     

Stream water, an ideal medium for rapidly locating polymetallic mineralization in forest-swamp terrain: a case study in the Da Hinggan Mts., northern Heilongjiang, China

A forest-bog landscape is developed in an area of moderate to low topography in northeastern China. Bogs are widespread along U- and V-shaped valleys (200–2000 m wide) and in depressions. Due to the cold climate, it was initially thought that chemical weathering would be slight in the area. However, a study of the geochemistry of surface water showed that, although most elements occur in relatively low concentrations compared to average contents in world river water, a number of mobile elements are dispersed over long distances. Marked Cu, Zn, Fe, Mn, and SO²⁻₄ anomalies, and relatively weak Ni, Co, Be, Pb and F anomalies form in stream water in the vicinity of known mineralization. Concentrations of Cu, Pb, Zn, Fe, and Mn in suspensates show no marked variations between background and anomalous streams whereas Ag exhibits a marked increase in suspensates near the mineralization. The pH of stream water near the mineralization is considerably lower than the 5 to 6.5 values recorded for background water. It can be concluded that water plays an important role in transporting elements chemically and stream water is a useful medium to sample in follow-up geochemical surveys for base and precious metals (Ag) in this landscape.     

Bed sediment-associated trace metals in an urban stream, Oahu, Hawaii

 Of the 117 stream and lake systems sampled nationwide, fish from Manoa Stream on Oahu, Hawaii, have consistently shown the highest Pb concentrations. Therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5.8-km stretch of Manoa Stream. A total of 123 samples (<63 μm) were examined for 18 elements and 14 samples for 21 elements. Selected samples were also examined using different leach solutions to examine metal phase associations. All trace metal data, computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for Cr and Ni; minor anthropogenic contamination for Ba, Cd, Cu, Hg and Zn; and a very strong contamination signal for Pb. Maximum Pb contents (up to 1080 mg kg⁻¹) were associated with anthropogenic material dumping in minor tributaries, storm sewer sediments and sediments in the “lower” section of the basin. Proportionally Pb had the highest non-residual component of elements examined; dominantly in the reducible phase associated with Mn and amorphous Fe oxyhydroxides. The contamination signal was typically lowest in the “undisturbed” headwater reach of the basin (above 5.1 km) with significant increases throughout the “residential” and “commercial-institutional” zones of the mid-basin. The spatial pattern of bed sediment contamination and evidence from storm sewer-outlet sediments strongly indicates that Pb, and to a lesser degree some other metals, is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments. The primary source of sediment-associated metals is considered to be the automobile, though other minor sources can not be ruled out. Received: 3 November 1998 · Accepted: 26 January 1999     

Trace elements distribution in stream sediments of an abandoned U mining site in the Eastern Carpathians,Romania, with particular focus on REEs

Trace elements distribution, including rare earth elements (REEs), in stream sediments of an abandoned U mining site in the Eastern Carpathians, Romania, were of high concern of interest in the present work. A total number of 40 riverbed sediments samples collected from the Bistricioara River and local tributaries (Primatar, Bradul, Prisacani, Barasau, Grintiesul Mare and Valea Seaca) were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and energy dispersive X-ray fluorescence spectrometry (XRF). All REEs including La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were identified and quantified in the present work using ICP-MS technique. For other 24 elements (Ti, V, Cr, Co, Zn, Li, Be, Rb, Sr, Y, Sc, Zr, Nb, Sb, Ba, Ta, W, Pb, U, Ni, Cu, Mo, As, Th) similar information was obtained either by ICP-MS or XRF techniques. The impact and the relevance of the obtained data base might be significant at a local scale of about 50 km².Enrichments of some trace elements of interest in comparison to the upper continental crust allowed discrimination between various mineralization processes specific for the investigated areas. Uranium mineralization and Paltin-type (Pb, Zn) mineralization seems to be specific for the NW area of the investigated region. Negative anomaly characteristic for the upper crustal rocks was identified for Eu and Ce elements. Evidences were obtained also for the existence of ultramafic rocks (Ni, Cr, Co and V) in the investigated riverbed sediments. The observation was also confirmed by the binary plots analysis of Th/Cr vs. Th/Co and Cr/V vs. Y/Ni pairs. From the investigated tributaries to Bistricioara River, Barasau seems to exert the highest influence on the abundances of REEss in the entire area. Most probably some chemical parameters such as the pH of the water streams influence leaching and depletions of some chemical constituents in various minerals specific for the region.The existence of magnetite, garnets, pyrite and sillimanite minerals was confirmed by SEM-EDAX and XRF analysis, as well by optical microscopy. Principal Component Analysis runs confirmed the association of some chemical elements in the riverbed sediments in close connection with the minerals from which they originate.The present work reports for the first time upon the authors knowledge clear scientific evidence and chemical information concerning the geology and geochemistry, i.e. transition metals, high field strength elements, alkali and alkaline earth elements, rare earth elements (REEs) and others, in stream sediments crossing the Tulghes-Grinties mining area (Eastern Carpathians, Romania). For the analysed REEs this is the first study reporting consistent information on the concentrations of the entire array of both light REEs (six elements) and heavy REEs (ten elements) in Bistricioara Basin stream sediments. Relevant scientific data related to geochemical characteristics of ultramafic rocks existent in the investigated area were also generated. Moreover, data reported in the present work might be considered as a reference geochemical database relevant for the investigated area, which can be used as a trustworthy input for a systematic national geochemical atlas.     

Mineralogical evolution of indium in high grade tin-polymetallic hydrothermal veins — A comparative study from Tosham, Haryana state, India and Goka, Naegi district, Japan

Two tin-polymetallic vein-type deposits widely separated in time and space but with strong similarities in terms of mineralization style, ore mineralogy and chemistry have been studied comparatively with the aim of understanding the mineralogical evolution of In-rich hydrothermal systems. The Tosham deposit, Bhiwani district, Haryana, India, is of Neoproterozoic age and constitutes a Sn–Cu prospect with unusually high In content. The disseminated, crude stockwork and vein mineralization is hosted by greisenised metasedimentary rocks intruded by a porphyritic granite stock and by later rhyolitic effusives. The Goka deposit, Naegi district, Japan is probably of uppermost Cretaceous age and occurs close to a well fractionated ilmenite series granitoid body. The tin-polymetallic vein in the Goka deposit is hosted by a welded tuff unit close to a subvolcanic granodiorite porphyry.The main host minerals of indium in the Tosham and Goka ores are sphalerite, stannite, unidentified Zn–Cu–Fe–In–Sn–S phases and chalcopyrite. Up to 0.48 wt.% In has been noted in the Goka chalcopyrite, whereas at Tosham, the mineral has a maximum In concentration of 1220 ppm. At Goka the sphalerite contains up to 1.89 wt.% In, whereas In-bearing stannite carries up to ca. 9 wt.% of the metal. Roquesite is the other indium mineral present in the Tosham ores, but is absent in Goka. The mineral chemistry of the Tosham and Goka ores suggest that the In-bearing minerals belong to a multi-component Zn–Cu–Fe–(Ag)–Sn–In–S system. Based on various triangular plots of the atomic proportions of the main metals, it is inferred that there are end-member phases, roquesite and stannite, in the Tosham ores co-existing with chalcopyrite. The sphalerite is both pure end-member and Cu–In-bearing in both the Tosham and Goka ores. Some of the analysed stannite grains in Tosham ores could possibly be petrukite. The Zn–Cu–Fe–Sn–In–S system in the two ores has a Sn-poor, high-In solid solution phase and also a Sn-rich, low-In solid solution phase. It seems possible that these two solid solutions were the first to form during hydrothermal ore deposition at high temperatures from a disordered solid solution located at the (Cu + Ag):(Zn + Fe):(In + Sn) = 3:5:2 intersection in the (Cu + Ag)–(Zn + Fe)–(In + Sn) field. With decreasing temperatures, the Sn-poor, In-rich solid solution exsolved the Zn–In-mineral of Ohta [Ohta, E., 1980. Mineralization of Izumo and Sorachi veins of the Toyoha mine, Hokkaido, Japan. Bulletin, Geological Survey of Japan 31, 585–597. (in Japanese with English abstract).] and sphalerite, while the Sn-rich, In-poor solid solution was broken down to stannite and relatively-Cu-rich sphalerite.     

Geochemical and Environmental Evaluation of Um Shashoba Gold Mine Area,Southeastern Desert,Egypt

A suite of elements(Ag,Au,Ba,Bi,Cd,Co,Cr,Cu,Ga,Hf,Hg,Mn,Mo,Ni,Pb,Rb,Sb,Se, Sr,Te and Zn),total organic carbon(TOC)and pH were analyzed in stream sediment and tailing samples from Um Shashoba area,in order to evaluate Au placer and the sediments being impacted by old mining activities.Analytical results were examined using statistical,graphical and mapping methods.In spite of the results revealing that Au and most of the elements in sediments were in general significantly lower than those in tailing,Au wa...     

Aquatic bryophytes as bioindicators of arsenic mineralization in Polish and Czech Sudety Mountains

Concentrations of arsenic and its geochemically associated elements, Ag, Co, Cu and Ni, were measured together with Al, Ba, Cd, Fe, Mn, Pb, Sr and Zn in aquatic bryophytes. These bryophytes originated from some of the arsenic mineralization zones of the Klodzko-Zloty Stok granodiorite massif and its metamorphic envelope (Sudetes Mts., Poland) and from identical zones of the east Sudetic Rychlebske Mts. and Jesenik Mts. (Czech Republic). Concentrations of As in all examined populations were higher than background values (1 μg/g dry weight) culminating in an average maximum of 6270 μg/g in Chiloscyphus pallescens from a stream draining an area with former arsenic and gold mining near Zloty Stok.This survey has shown that aquatic bryophytes accumulate the examined elements to a high degree especially if growing in areas with mineral deposits. This was demonstrated by strong positive correlations between Ba, Sr, Zn concentrations in water and Platyhypnidium rusciforme.     

Stream sediment geochemical exploration for gold in Central Eastern Desert,Egypt: Application of the concentration-number fractal model,factor analysis,and geochemical mineralization probability index

Geochemical exploration by stream sediment sampling using bulk leach extractable gold (BLEG) technique and applying concentration-number (C-N) fractal model, factor analysis (FA), and geochemical mineralization probability index (GMPI) resulted in the recognition of new Au occurrences around the Sukari gold mine in the central Eastern Desert of Egypt. The geochemical data of 128 stream sediment samples collected from the study area was used for delineating the geochemical anomalies and characterizing the dispersion trains of ore and associated elements (Au, Ag, As, Sb, Cu, Pb, Zn, Mo). Statistical analysis of the geochemical data applying the C-N fractal modeling enabled us to identify significant anomaly and background populations of the investigated elements and to construct reliable geochemical anomaly maps. Factor analysis using centered log-ratios (CLR), to address the problem of closed compositional data, revealed significant element associations for mineralization (Au, As, Mo, Zn, Ba), country rock compositions (Rb, Li, Be, Sn, Bi for granite, and Co, Cr, Ni for mafic rocks), and element mobility (e.g. Sb, Zr, and Ag). Weak and moderate Au anomalies that cannot be detected by factor score maps can be delineated clearly by using the C-N fractal method and GMPI distribution map. Our study revealed that Ag, As, and Sb are the main pathfinder elements for gold mineralization in arid to semiarid regions exemplified by the Sukari gold district. Silver can be used as a “direct” pathfinder, whereas As and Sb are “indirect” pathfinders for Au in such regions. The spatial distribution of Au and Ag anomalies indicate that gold mineralization in the Sukari district is structurally controlled. However, the spatial distribution of Cu, Pb, Zn, and Mo is controlled by mineralogical and lithological factors and is not related to any significant base metal deposits.     

Proton-induced X-ray emission measurements of trace elements in water samples collected from an Indiana coal mining locality

A new method of simultaneous multi-elemental analysis, Proton Induced X-ray Emission (PIXE), was used to detect trace elements in waters associated with a coal strip-mining operation in southern Indiana. Stream, pond, and ground water samples were collected and analyzed monthly from, or near, Sulphur Creek in Sullivan County. The concentrations of 26 major and trace elements were determined in samples from eleven locations: K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Mo, Cd, Sn, Sb, I, Ba, Hg, Pb, and U. Elemental concentrations fluctuated considerably throughout the 13-month sampling period and also among sampling sites. Nickel, Zn, As, Cd, Mn, Fe, and Ca were highest in the upstream water which was most acidic (pH = 2.9–4.0) because of old unreclaimed mining operations. The highest values recorded were Ni = 1662 ppb, Zn = 4953 ppb, As = 26 ppb, Cd = 93 ppb, Mn = 5063 ppb, Fe = 63 ppm, and Ca = 325 ppm. The concentrations of these elements decreased downstream as the pH of Sulphur Creek increased which was likely due to the influence of the calcareous glacial till cover in the area and the recent mining activity which disturbed overburden containing a high percentage of calcareous materials. Lead, I, Br, and Ti values were highest (661 ppb, 86 ppb, 70 ppb, and 45 ppb, respectively) in the ground water from the coal seam (pH approximately 7). Other elements which were relatively high in the pH 7 waters closest to the current mining operations (pond, stream, and groundwater) included K (17 ppm), Sr (3408 ppb), Ba (173 ppb), As (14 ppb), Rb (16 ppb), Sn (14 ppb), and Cu (3840 ppb). The highest Cu concentration was recorded at the point where drainage water from the mine entered Sulphur Creek. Gallium, U, Hg, and Mo were found in low (< 13 ppb for Ga and Hg; < 205 ppb for Mo and U) concentrations and only in the ponds within the mine.     

Impact of historical metalworks on the concentrations of major and trace elements in sediments: a case study in Finland

The concentrations of major and trace elements were determined (aqua regia leach and ICP-AES analyses) in stream, lake and dredged sediments downstream of the historical Antskog iron- and copperworks, S.Finland. The levels of Ag, Cd, Cu, Pb and Zn are highly elevated in all studied sediment types: roughly half of the studied lake-sediment samples contain >5 ppm Ag, >15 ppm Cd, >0.1% Cu, >0.1% Pb and >0.3% Zn. In the dredged sediment material located onshore, the concentrations of Ag, Cu and Pb are comparable to those in the polluted lake-sediment samples, while in stream sediments elevated metal concentrations are found especially in samples characterised by high concentrations of organic material. The source of the elevated metal concentrations is the historical metalworks at Antskog, mainly the copperworks of the 19th century. Compared to the limit values for contaminated soils in Finland, the concentrations of Cu, Pb and Zn are on average elevated by factors >10 in the polluted horizons of lake sediments, >5 in the dredged sediment located onshore and >2 at the most heavily contaminated site in the stream. Since the surface waters in the area are used for agricultural purposes and for various leisure activities, it is necessary to make further detailed investigations into the extent of the metal pollution and to determine species, mobility and bioavailability of the metals.     

Bryolithochemical studies in the search for and evaluation of gold-silver mineralization based on stream sediments (northeastern Russia)

The first bryolithochemical studies have been carried out within the Dukat ore field (Balygychan-Sugoi trough, northeastern Russia), in its northeast (Dukat Au-Ag deposit, Chaika site) and on its eastern flank (Au-Ag ore occurrence, Piritovyi site). Sampling was made along primary water streams draining Au-Ag ore zones, because the headstreams localized in the permafrost zone are poor in alluvial sediments or lack them, whereas the stream banks and beds are overgrown with aquatic and semiaquatic mosses. We examined samples of moss cushions with loose sediments (fine silt suspension and sand-silt material). The study has shown that moss cushions are an effective natural trap extracting finely dispersed, ultradisperse, and colloid-dispersed particles, including ore ones, from water stream suspension. The contents of major elements indicating Au-Ag mineralization (Au, Ag, Hg, Sb, As, Pb, and Zn) in the bryolithochemical and lithochemical samples were compared. The highest contents of these elements have been revealed in the bryolithochemical samples. Scintillation analysis shows a predominance of finely dispersed Au and Ag particles. The chemical composition of lithoparticles and probable species of elements indicating mineralization were studied by energy-dispersive X-ray microanalysis. It has been concluded that the bryolithochemical stream sediments are an integral part of the lithochemical ones and can also be effectively used to reveal geochemical anomalies and identify the corresponding ores. It is shown that the bryolithochemical sediment streams bear important information about the chemical composition of primary ores, as they have the same major indicator elements (Au, Ag, Hg, Sb, As, Pb, and Zn) and nearly the same mineral composition (finely dispersed gold and silver, electrum, silver sulfosalts, and simple sulfides). The proposed bryolithochemical research is promising not only for northeastern Russia but also for other areas with similar landscapes, primarily areas where lithochemical and bryolithochemical stream sediments form in the northern subarctic and arctic environments.     

A rapid, partial leach and organic separation for the sensitive determination of Ag, Bi, Cd, Cu, Mo, Pb, Sb, and Zn in surface geologic materials by flame atomic absorption

A solution of dilute hydrochloric acid, ascorbic acid, and potassium iodide has been found to dissolve weakly bound metals in soils, stream sediments, and oxidized rocks. Silver, Bi, Cd, Cu, Mo, Pb, Sb, and Zn are selectively extracted from this solution by a mixture of Aliquat 336 (tricaprylyl methyl ammonium chloride) and MIBK (methyl isobutyl ketone). Because potentially interfering major and minor elements do not extract, the organic separation allows interference-free determinations of Ag and Cd to the 0.05 ppm level, Mo, Cu, and Zn to 0.5 ppm, and Bi, Pb, and Sb to 1 ppm in the sample using flame atomic absorption spectroscopy. The analytical absorbance values of the organic solution used in the proposed method are generally enhanced more than threefold as compared to aqueous solutions, due to more efficient atomization and burning characteristics. The leaching and extraction procedures are extremely rapid; as many as 100 samples may be analyzed per day, yielding 800 determinations, and the technique is adaptable to field use.The proposed method was compared to total digestion methods for geochemical reference samples as well as soils and stream sediments from mineralized and unmineralized areas. The partial leach showed better anomaly contrasts than did total digestions. Because the proposed method is very rapid and is sensitive to pathfinder elements for several types of ore deposits, it should be useful for reconnaissance surveys for concealed deposits.     

Reconstruction of the hydrothermal history of the Cu–Ag vein-type mineralisation at Dikulushi, Kundelungu foreland, Katanga, D.R. Congo

The Kundelungu foreland, north of the Lufilian arc in the Democratic Republic of Congo, contains a number of various vein-type and stratiform copper mineralisations. The geodynamic context and metallogenesis of these mineral occurrences remain enigmatic. Currently, the vein-type Cu–Ag ore deposit at Dikulushi is the most significant deposit in the region. Mineralisation at Dikulushi comprises two major styles: 1) a polysulphide assemblage (Zn–Pb–Fe–Cu–As) within brecciated rocks along an anticlinal closure; and 2) a vein-hosted Cu–Ag assemblage. Petrographic and fluid inclusion studies indicate that the early Zn–Pb–Fe–Cu–As assemblage formed from a high-salinity Ca–Na–Cl fluid of modest temperature (135–172 °C). The later, economically more significant vein-related Cu–Ag mineralisation formed from intermediate salinity, lower temperature (46–82 °C) Na–Cl fluids. Weathering of the sulphide minerals resulted in a supergene enrichment with the formation of secondary Cu-minerals.     

Surface geochemical and biogeochemical expression of base‐metal mineralization at Woodlawn,New South Wales,Australia

The presence of base‐metal mineralization at Woodlawn was first recognised early in 1968 when a roadside reconnaissance geochemical sampling survey, conducted over felsic volcanic rocks in the Goulburn‐Tarago area, encountered anomalous B horizon soils containing up to 200 ppm Cu, 800 ppm Pb and 300 ppm Zn. Regional soil thresholds have been determined at 50 ppm Cu, 90 ppm Pb and 50 ppm Zn. Chip samples from the subsequently located gossan revealed up to 2000 ppm Cu, 8000 ppm Pb and 2000 ppm Zn, 500 ppm Sn, 25 ppm Ag and 3000 ppm As.

The first grid B horizon soil geochemical survey was conducted in 1968 over the gossan and surrounding area, and repeated with closer spaced sampling in the first half of 1970. The first survey delineated strong Cu (to 1000 ppm) and Pb (to 2500 ppm) anomalies coincident with the gossan zone, and intense hydromorphic zinc anomalies (to 3000 ppm) located down slope from the gossan in residual clay‐soils derived from dolerite bedrock. Threshold values have been determined at 140 ppm Cu, 700 ppm Pb and 580 ppm Zn. Ag and Sn in B horizon soils show pronounced anomalies coincident with the gossan and are suitable metals for geochemical target definition. Of fourteen trace elements determined in 1974 from B and C horizon soils on two lines across the ore zone Cu, Pb, Zn, Se, Ba, Sn and Ag show direct correlation with the mineralization, whereas Cd and Mn show moderate hydromorphic dispersion, having accumulated principally in clay soils derived from dolerite weathering. As, Sb and Bi, whilst responding over the ore zone, show elevated values in soils over hanging‐wall units; Ni and Co show maximum levels in soils over dolerite bedrock.

Bark and leaves of Acacia mearnsii, collected from a line across the gossan, contain anomalous levels of Cu, Pb, Zn, Sn and Ti near the ore zone, and weaker, but clearly anomalous Mn and Ni levels over dolerite bedrock. Both bark and leaves of Acacia mearnsii reflect the presence of concealed mineralization. The shrub Solanum linearifolium grows preferentially over and close to the Woodlawn ore zone, where it contains up to 840 ppm Cu, 250 ppm Pb, 7300 ppm Zn, 6 ppm Sn and 250 ppm Ti in leaf ash compared with levels of 200 ppm Cu, 2 ppm Pb, 400 ppm Zn, 0.8 ppm Sn and 60 ppm Ti in plants growing 1.5 km from the ore zone. This shrub has potential as an indicator of base‐metal mineralization.     

Lithogeochemistry of wainaleka Cu-Zn volcanogenic deposit, Viti Levu, Fiji, and possible applications for exploration in tropical terrains

A small Kuroko-type Cu-Zn deposit exhibiting metal zoning and alteration assemblages comparable with documented proximal volcanogenic deposits, occurs at the top of a felsic fragmental pile, mantling a large sodic rhyolite domal complex. The domal complex occurs within predominantly mafic to intermediate lavas and volcaniclastic rocks with low-potash island-arc tholeiitic affinities, representing the basal section of the early Tertiary (Eocene to middle Miocene) Wainimala Group near the southern coast of Viti Levu, Fiji.Lithogeochemical trends identified in analyses of rock chip samples from traverses across the domal complex reflect alteration zoning. Sodium, Ca and Sr are strongly depleted within the quartz-sericite foot-wall alteration zone (Zone I) 200 m below mineralization. Potassium, Rb and weaker Mn, Zn and Co depletion and Cu, Pb and Mg enrichment define clay-sericite (Zone II) and clay carbonate (Zone III) footwall alteration 600 to 1200 m below mineralization. Hanging-wall albite-chlorite-calcite-zeolite alteration (Zone IV) is accompanied by enhanced Zn, Pb, Co, Mn, Sr and Na values.Significant mine-scale lithogeochemical trends obtained from systematic sampling of a mineralized borehole section include K and Rb enrichment in the zone of strongest quartz-sericite alteration associated with mineralization and broad depletion of Mn, Na, Ca and Sr within altered footwall fragmental rocks. Minor Cu, Pb, Zn and Ag enrichment has accompanied low-grade propylitic alteration of hanging-wall rocks up to 50 m above mineralization. Analysis of weathered bedrock samples from traverses above the mineralized borehole section indicates that primary geochemical trends occur in the weathered zone. Outcropping gossan has strongly anomalous Cu (535 ppm-21.5%), Zn (3300 ppm-6.15%), Pb (420–8200 ppm), As (200–7000 ppm) and Hg (33–670 ppm) values.Application of lithogeochemistry as a follow-up exploration method in a tropical area such as Wainaleka was investigated as a possible replacement for ridge, spur and base-of-slope soil sampling techniques. Ridge-top auger samples and creek outcrop samples were collected at approximately 100 m intervals and a density of 70/km². Elements (including Cu, Pb, Zn, Mn, Rb, Sr, Na, K, Ca and Mg) were selected for analysis because of specific associations with mineralization and alteration, and low analytical costs. Single- and multi-element dispersions effectively outline mineralization and attendant alteration.     

酸性矿山排水影响的水库沉积物微量元素地球化学特征

为了解酸性矿山排水（AMD）影响下水库沉积物中微量元素的质量分数水平及其分布特征,对常年受酸性废水影响的贵州兴仁猫石头水库沉积物中26种微量元素的质量分数、相关性及控制因素进行了分析。结果表明：猫石头水库沉积物柱中Sr、Ba、Zr、V、Cr和As质量分数平均值超过了100 μg/g,其中As质量分数最高,平均值超过800 μg/g;Be、Ta、Co、Ag、Cd、Sn和Se质量分数的平均值都在5 μg/g以下;其他元素质量分数平均值则在10~60 μg/g之间。相较未受AMD影响的水系沉积物,研究区水库沉积物具有明显的As和Sb富集特征。水库沉积物中Li、Be、Rb、Sr、Cs、Ba、Sc、Y、Zr、Hf、Nb、Ta、Th之间存在显著正相关关系,而As与这些元素之间存在显著负相关关系。元素相关分析、因子分析及微量元素图解表明,Li、Be、Rb、Sr、Cs、Ba、Sc、Y、Zr、Hf、Nb、Ta、Th、Cr、Sb等元素受控于流域岩石化学风化和土壤物理侵蚀,这也是控制研究区元素分布最重要的因素,而Cu、Cd等重金属元素则与AMD对地层中元素的溶蚀析出和有机质等细颗粒物的吸附有关。另外,研究区重金属元素中,Cd、Cu、Pb、Cr、Zn的生态风险轻微,而As和Sb则具有很强的潜在生态风险。