Dispersal Trains Research Articles

Interaction of natural organic matter with acid mine drainage: In-situ accumulation of elements

Natural organic matter (NOM) within the dispersion train of Novo-Ursk tailings (Salair Ridge, Kemerovo region, Russia) is composed of remnant sedge peat mounds and is located either on the surface or is buried under cyanide wastes. The organic material interacts with AMD and with the wastes, which leaves imprint on its composition. This interaction produces geochemical anomalies (g/t: 1582 Cu, 41,300 Zn, 6060 Se, 11,700 Hg, 114–155 Au, 534 Ag, 416 I). The contents of elements depend on Fe in three groups of NOM samples that contain <10 wt% Fe (group I), 10–22 wt% Fe (group II), and >22 wt% Fe (group III). NOM with higher Fe enrichment contains less Cu, Zn, Se, Hg, Ag and I, as well as Cd, Ba, Sr and Rb, Y, Zr, Nb, Mo, Sn, Sb, and Te but more As. Yet, gold may reach high concentrations in NOM with any Fe contents. Accumulation of elements by NOM during its prolonged interaction with wastes and AMD is maintained by physical, chemical, biochemical, and mineralogical processes. They are, respectively, migration of waters controlled by permeability of material in the dispersion train depending on its grain sizes and by AMD flow direction; oxidative dissolution of sulfides, complexing, and adsorption on organic matter and Fe(III) hydroxides; microbial mediation; and secondary mineralization. The chemistry of waters interacting with NOM at the time of its deposition can be reconstructed with regard to several factors, including microbial mediation. Namely, local geochemical anomalies with ultrahigh element concentrations may arise because microorganisms can immobilize Hg to make it less toxic; sulfate-reducing bacteria can maintain precipitation of Zn, Cu, and Cd sulfides; microbial activity can mediate redistribution of elements between clastic and organic materials, etc. The inferred inheritance of AMD geochemical signatures by NOM has implications for the conditions and mechanisms of element accumulation.

Acid Mine Drainage Contamination of the Ur Impoundment: Environmental Geochemistry

Water, particulate matter, and bottom sediments of the Ur impoundment used for fishing have been analyzed in terms of environmental geochemistry. The impoundment is located within the dispersion train of gold-bearing sulfide tailings at the Ur ore field and has been contaminated by acid mine drainage (AMD). The depth-dependent distribution of elements in the bottom sediments corresponds to (1) pre-mining, (2) early mining, and (3) post-mining (present) stages. Sediment enrichment in Cu, Cd, Fe, Pb, Zn, As and Hg depends on their speciation and migration patterns in water. The concentrations of many elements in water and bottom sediments exceed maximum allowable values. Hg occurring as the most toxic methyl compound poses the greatest hazard.

Glacial dispersal trains in North America

ABSTRACTA map depicting glacial dispersal trains in North America has been compiled from published sources. It covers the Canadian Shield, the Arctic Islands, the Cordillera and Appalachian mountains, and Phanerozoic sedimentary basins south of the Shield. In total, 140 trains are portrayed, including those emanating from major mineral-deposit types (e.g. gold, base metal, diamondiferous kimberlite, etc.). The map took 10 years of on-and-off work to generate, and it culls data from over 150 years of work by government, industry, and academia. It provides a new tool to help companies find ore deposits in Canada: the trains are generally a better predictor of dispersal distance and direction than striations and streamlined landforms, the data typically depicted on surficial-geology maps, including the Glacial Map of Canada. It also gives new insight into sedimentation patterns and processes beneath ice sheets, a sedimentary environment that, because of its inaccessibility, remains poorly understood and controversial.

Geometry of indicator mineral and till geochemistry dispersal fans from the Pine Point Mississippi Valley-type Pb-Zn district, Northwest Territories, Canada

An indicator mineral and till geochemical dispersal case study was conducted at the Pine Point Mississippi Valley-type (MVT) Pb-Zn district in northern Canada to document glacial dispersal down ice from a known orebody. Indicator minerals in the non-ferromagnetic heavy mineral (specific gravity >3.2) concentrate of till down ice of the mined-out O-28 Pb-Zn deposit in the east end of the district include sphalerite, galena, and pyrite, as well as secondary Pb-Zn minerals anglesite (as coatings on galena), smithsonite, and cerussite. These minerals are sufficiently physically and chemically robust to survive glacial transport as well as post-glacial weathering in the carbonate-rich till of the region. Pathfinder elements in the <0.063 mm fraction of till, determined using a modified aqua regia digestion, include Zn, Pb, Cd, Tl, and S.Evidence for multiple ice flow phases, each with an erosional and depositional record across the district, includes cross-striated bedrock surfaces, streamlined landforms, and till clast fabrics. At the O-28 pit, two main phases of ice flow eroded and dispersed Pb- and Zn-rich debris first to the southwest and then to northwest, producing a fan-shaped palimpsest dispersal train defined best by indicator minerals, but also by till geochemistry. The last ice-flow phase during deglaciation had a minimal effect on the dispersal train geometry. This case study presents another example of complex glacial transport and dispersal by multiple ice flows that have been defined by both glacial ice flow indicators and glacial transport data. Complex ice flow and transport are to be expected over large parts of the glaciated terrain of Canada.The key implications of this study to mineral exploration are that: 1) till sampling is a viable exploration method in the district; 2) in the eastern part of the district where the till is generally thin (<5 m), surface till sampling will be cost effective; further west where till cover exceeds 30 m overburden drilling methods will be needed to collect till samples at depth; 3) indicator minerals and till geochemistry (transport data) combined with the reconstructed phases of ice flow define a palimpsest pattern of glacial transport in the region.

The Blackwater gold-spessartine-pyrolusite glacial dispersal train, British Columbia, Canada: Influence of sampling depth on indicator mineralogy and geochemistry

A comprehensive program of indicator mineral and geochemical sampling of both oxidized and unoxidized till at the glaciated Blackwater Au-Ag deposit in the interior of south-central British Columbia, Canada has provided key insights into glacial and post-glacial dispersal patterns that can be used to explore other glaciated regions more effectively. The Blackwater deposit is located on the northeastern slope of Mount Davidson and is completely covered by till that was deposited by NE-flowing ice. Only the sulphide-depleted supergene cap of the deposit was exposed to the ice. Indicator mineral sampling of C-horizon till on the mountain slope identified a 1.3 km wide gold grain dispersal train that extends c. 3 km glacially down-ice and 200 vertical metres down-slope from the deposit. The till within this train contains from 10 to 641 gold grains, dominantly of 25 µm size, per 10 kg of its &lt;2 mm matrix. As well, the 0.25 – 0.5 mm fraction contains up to 25 000 grains per sample of spessartine garnet derived from the hypogene alteration envelope of the Blackwater deposit, increasing the probable detectable length of the train to 10 km. Geochemically, in the &lt;0.063 mm fraction of the till, the detectable length of the train is reduced to &lt;1 km, with the best indicator elements being Au and Zn. In drill holes, the host till is oxidized to a depth of 2 – 5 m. It thickens markedly downslope from a few metres to c. 100 m. The gold-spessartine dispersal train thickens sympathetically to nearly 30 m and also ascends progressively within the till section. Gold grain and spessartine levels in the unoxidized till at depth are similar to those in the oxidized till at surface but the unoxidized till also contains up to 60 000 grains per sample of metal-rich pyrolusite derived from supergene cap of the Blackwater deposit.

Redistribution of elements between wastes and organic-bearing material in the dispersion train of gold-bearing sulfide tailings: Part I. Geochemistry and mineralogy.

Migration and redistribution of elements during prolonged interaction of cyanide wastes with the underlying natural organic-bearing material have been studied in two ~40cm deep cores that sample primary ores and their weathering profile (wastes I and II, respectively) in the dispersion train of gold-bearing sulfide tailings in Siberia. Analytical results of SR-XRF, whole-rock XRF, AAS, CHNS, and SEM measurements of core samples show high K, Sr, Ti, and Fe enrichments and correlation of P2O5 and Mn with LOI and Corg. Organic material interlayered or mixed with the wastes accumulates Cu, Zn, Se, Cd, Ag, Au, and Hg. The peat that contacts wastes II bears up to 3wt.% Zn, 1000g/t Se, 100g/t Cd, and 8000g/t Hg. New phases of Zn and Hg sulfides and Hg selenides occur as abundant sheaths over bacterial cells suggesting microbial mediation in sorption of elements. Organic-bearing material in the cores contains 10-30g/t Au in 2-5cm thick intervals, both within and outside the intervals rich in sulfides and selenides. Most of gold is invisible but reaches 345g/t and forms 50nm to 1.5μm Au0 particles in a thin 2-3cm interval of organic remnants mixed with wastes I. Vertical and lateral infiltration of AMD waters in peat and oxidative dissolution of wastes within the dispersion train of the Ursk tailings lead to redistribution of elements and their accumulation by combined physical (material's permeability, direction AMD), chemical (complexing, sorption by organic matter and Fe(III) hydroxides) and biochemical (metabolism of sulfate-reducing bacteria) processes. The accumulated elements form secondary sulfates, and Hg and Zn selenides. The results provide insights into accumulation of elements in the early history of coal and black shale deposits and have implications for remediation of polluted areas and for secondary enrichment technologies.

Student academic performance in rural clinical schools: The impact of cohort size and competition

Objectives: The Deakin University School of Medicine commenced in 2008 as a rurally focused medical school in south-eastern Australia. This research was designed to examine the effectiveness of the school’s adoption of small regional clinical school settings.Methods: A retrospective cohort study of the first two cohorts of students was employed to assess academic performance at each of five geographically dispersed clinical training sites, with varying student cohort sizes. The Dundee Ready Education Environment Measure (DREEM) questionnaire provided quantitative data regarding the students’ perception of their educational environment. The data were analyzed using univariate and multivariate analyses.Results: The highest examination scores, and greatest satisfaction with educational environment, were associated with the clinical school that had a small-sized group of students and was not co-located with another medical school. These differences remained after adjusting for multiple potential confounding factors.Conclusion: The smaller sites appear to have provided superior support for student learning in this new medical school. This advantage diminishes when smaller cohorts are co-located with students from other medical schools. Cohort size and co-location of medical school curricula may be important independent variables for researchers to consider when comparing the results of clinical education innovations in different settings.

Application of Multivariate Statistical Delineation of Prospective Geochemical Providenskaya Area (Chukotka, Russia)

The secondary geochemical field structure was modelled on the basis of the lithogeochemical dispersion trains of the Providenskaya Area of the Chukotka Peninsula. The factor and cluster analysis were applied to interpret the nature of geochemical anomalies. It was proved that a range of anomalies were prospective for gold-silver, polymetallic, tin, and tungsten deposit allocation.

Till geochemistry and mineralogy: vectoring towards Cu porphyry deposits in British Columbia, Canada

Regional till sampling was completed near four Cu porphyry mineralized zones in south-central British Columbia, Canada: Highland Valley Copper (Cu-Mo), Gibraltar (Cu-Mo), and Mount Polley (Cu-Au-Ag) deposits, and the Woodjam (Cu-Au-Mo) prospect. At all sites, Cu concentrations in the clay-sized fraction and chalcopyrite grains (0.25 – 0.5 mm; &gt;3.2 specific gravity) are found in greater abundance in till near and down-ice from mineralized zones compared to surrounding background regions. At Mount Polley, the abundance of gold grains in till defines a dispersal train extending at least 3 km down-ice (SW and NW) from mineralization. At three sites out of four, epidote in till heavy mineral concentrates occurs in greater percentage near and down-ice from mineralized zones compared to background regions suggesting that this mineral could be an indicator of propylitic alteration associated with porphyry mineralization. The distribution pattern of Cu concentrations and chalcopyrite grains in till is controlled by the distribution of Cu-porphyry mineral occurrences in bedrock and the direction of ice-flow movements which prevailed during the last glaciation. By comparing study sites, there is a positive relationship between the areal extent of bedrock mineralization that was exposed to glacial erosion and the absolute values of Cu concentrations and chalcopyrite grain counts in till. In the Woodjam region where the till is thick (&gt;10 m), eight samples with background Cu concentrations in the clay-sized fraction of till contain &gt;4 grains of chalcopyrite/10 kg which is indicative of mineralization. This study demonstrates that a combination of till geochemistry and mineralogy is an efficient method for mineral exploration for Cu porphyry deposits covered by variable amounts of glacial sediments. Supplementary material: The full data sets on till geochemistry and mineralogy are available at: https://doi.org/10.6084/m9.figshare.c.3291503

Till Geochemistry in West-Central Manitoba: Interpretation of Provenance and Mineralization Based on Glacial History and Multivariate Data Analysis

Till geochemical datasets from archived samples in west-central Manitoba are interpreted using multivariate data analytical techniques such as principal component analysis and pathfinder element index methods, combined with a spatial representation of the data in a geographic information system (GIS). Results show that carbonate till derived from Hudson Bay, as expressed by the (Ca + Mg)/Na ratio, is found predominantly east of Leaf Rapids and extends south into the Northeastern Kisseynew Domain. A 30- to 70-km-wide zone is documented beyond the limit of dissolvable carbonate dispersal that contains till of Labradorean provenance with low Ca-Mg-Mn-Te concentrations, noncalcareous till of Keewatin provenance, and silty calcareous till at depth. The variation in till provenance, together with the predominance of southwesterly ice-flow indicators, suggests that carbonate dispersal occurred prior to deglaciation, and that surface tills in the zone of confluence between Labradorean and Keewatin ice are likely the result of recycling of calcareous tills and/or carbonate-leached sandy tills, mainly by Keewatin ice. The newly defined limits of carbonate and Ca-rich till, typically used to assess provenance and glacial transport, provide a new framework for evaluating the significance of till geochemical patterns when drift prospecting over the Trans-Hudson orogen. Several regional- to local-scale dispersal trains from geochemically distinct bedrock sources are discussed in terms of elemental association, glacial transport characteristics, and potential bedrock sources. The multivariate statistical approach combined with GIS mapping also highlights new areas with small multi- or single-element enrichments that may be of further interest for volcanogenic massive sulfide exploration or for potentially more detailed drift sampling.

Sedimentary record of ice divide migration and ice streams in the Keewatin core region of the Laurentide Ice Sheet

The Aberdeen Lake region of central mainland Nunavut is a former core region of the Laurentide Ice Sheet that is characterized by streamlined glacial landforms classified into multiple crosscutting flow sets and near continuous till blanket. The presence of widespread till near the centre of the Keewatin Ice Dome raises questions about its origin. Detailed drillcore logging revealed a complex stratigraphy consisting of at least 6 till units, variably preserved across the study area. Till provenance analysis indicates deposition by near opposite-trending ice flow phases, interpreted as evidence of reconfiguration of the Keewatin Ice Divide. At the surface, large north–northwesterly aligned landforms are present across the study area. The till stratigraphy within these landforms indicates the same NNW ice flow phase is responsible for considerable till production. This ice flow phase is also correlated to a long regional dispersal train of erratics toward the Gulf of Boothia. The production of an extensive, thick (~12m), till sheet during the NNW-trending ice flow phase occurred far from the ice margin at a time of extensive ice cover of mainland Nunavut, likely from an east–west oriented ice divide. A deglacial westerly trending ice flow phase formed small drumlins atop the larger NNW streamlined till ridges and deposited a surficial till unit that is too thin to mask the NNW flow set across the study area. It is proposed that the Boothia paleo-ice stream catchment area propagated deep into the Laurentide Ice Sheet and contributed to significant till production in this core region of the Keewatin Sector prior to the westerly ice flow shift. The apparent relationship between till thickness and the size of the associated or correlated drumlins, flow sets, and dispersal trains indicates complex erosion/deposition interplay is involved in the formation of streamlined subglacial landforms.

DEFINITION OF ENERGY SAVING ACCELERATION MODES OF TRAINS

Purpose. In modern conditions of rolling stock operation, the actual vital task is the increasing the efficiency of its use by reducing the cost of energy, including for the traction. It can be achieved by the way of locomotives power control systems creating, in particular the use of operating cards and on-board software and hardware. Methodo-logy. The article discusses ways of starting and acceleration of the train. Traction calculations with the definition of energy-efficient trajectories provide the search of a rational consumption of energy with time of running trains. When selecting energy saving train trajectories and the development of operating trains of reference cards, it is necessary to consider the variables such as: the profile area, weight of the stock, series of the locomotive and others. When the transmission power from the primary power equipment to the driving wheel pairs the inevitable losses that are described by the efficiency factor occur. For the most part of the locomotive elements the dependences of the efficiency factor are described by the nonlinear equations. Getting the energy-saving function of traction control at starting and acceleration to reduce the specific consumption of energy by improving the algorithm for calculating the trajectories of multiple trains was considered. The method of selection of energy-efficient trajectories at dispersal trains and power control electric and diesel locomotives with electric transmission which bases on the mathematical methods for evenly search and parametric optimization was offered. Findings. For the variables of the train situation and rolling stock was built two-parameter functional dependence of the power control locomotive and analytically determined the effectiveness of the proposed algorithm. Originality. In the work result the authors received the power saving function of traction control, which depends on the mass of the rolling stock and slant. In contrast to existing development of rational management of trains, this function requires much less computer time with a high accuracy of the calculations, which makes it possible to incorporate it into the onboard control system of the locomotive and energy savings. Practical value. Experimentally established algorithm, which is part of the on-board software package definition of energy-saving modes of conducting trains, will contribute to the reduction of energy expenses.

Principal component analysis of magnetite composition from volcanogenic massive sulfide deposits: Case studies from the Izok Lake (Nunavut, Canada) and Halfmile Lake (New Brunswick, Canada) deposits

Magnetite grains from the Izok Lake (Nunavut, Canada) and the Halfmile Lake (New Brunswick, Canada) volcanogenic massive sulfide deposits, and from till covering the nearby areas were investigated using the scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and optical microscopy. The method of robust estimation for compositional data (rob-composition) was applied to censored geochemical data, and the results were analyzed by principal component analysis (PCA). Textural relationships and mineral association of magnetite reveal the history of formation, and contribute to the explanation of characteristic compositional differences of magnetite from different geological settings. The integration of petrography and mineral chemistry allows discriminating magmatic, metamorphic and hydrothermal magnetite grains in the VMS deposits bedrock samples. Magmatic magnetite is found in Izok Lake gabbro, and Halfmile Lake syenite, felsic ash tuff and gossan samples, whereas magnetite in Izok Lake massive sulfides, gahnite-rich dacite and iron formations formed during the amphibolite facies metamorphism. In Halfmile Lake andesite, magnetite recrystallized during greenschist facies metamorphism. In the magnetite alteration zone associated to the Halfmile Lake deposit, hydrothermal magnetite has been overprinted by metamorphic magnetite. Halfmile Lake massive sulfides in chloritic argillite contain hydrothermal magnetite.PCA identifies discriminator elements and their contributions to magnetite composition from different Izok Lake Lake and Halfmile Lake bedrock samples. The results suggest that Si, Ca, Zr, Al, Ga, Mn, Mg, Ti, Zn, Co, Ni and Cr are discriminator elements for VMS deposits and their host bedrocks. The distinct chemical signatures for magnetite from various bedrock lithologies demonstrate that magnetite grains of the same origin share more similarities in chemistry, as high Ti indicates magmatic sources for magnetite, whereas high Si, Ca and Mg are indicative of hydrothermal settings. Variable compositions of metamorphic magnetite suggest that the chemistry of this type of magnetite is controlled by the composition of host rocks, the grade of metamorphism and oxygen fugacity. PCA of EPMA and LA-ICP-MS data of magnetite from the Izok Lake and Halfmile Lake bedrock samples yield discrimination models for classification of magnetite grains from till. Decreases in the proportion of magnetite grains with the chemical signature of the Izok Lake massive sulfides and gahnite-rich dacite down-ice from the Izok Lake deposit show the use of magnetite chemistry in geochemical exploration. In the Halfmile Lake area, till magnetite grains with the signature of VMS mineralization make a glacial dispersal train more than 2km down-ice from the deposit.

Glacial dispersal of gahnite from the Izok Lake Zn-Cu-Pb-Ag VMS deposit, northern Canada

The Izok Lake Zn–Cu–Pb–Ag volcanogenic massive sulphide (VMS) deposit in the Arctic region of Canada is one of the largest undeveloped Zn–Cu VMS resources in North America. In 2009, the Geological Survey of Canada initiated a detailed glacial dispersal study of the deposit focused on documenting its associated indicator mineral and till geochemical signatures. Glacial dispersal from the deposit is fan-shaped and was formed by an older SW ice flow and younger NW ice flow phases. Till samples contain chalcopyrite, sphalerite, galena, and pyrite up to 1.3 km down-ice and gahnite at least 40 km down-ice. Gahnite (ZnAl 2 O 4 ) is an ideal indicator mineral in till because of its visually distinctive bluish green colour combined with its high specific gravity (4–4.6) for recovery using density-based separation methods, moderate hardness (physical durability during glacial transport), chemical stability in oxidizing surficial environments (resistance to post-glacial weathering), and its occurrence in highly metamorphosed VMS deposits such as Izok Lake. Most gahnite grains in till down-ice are 0.25–0.5 mm in size. Coarser gahnite (0.5–2.0 mm) occurs only in till proximal to the deposit (&lt;3 km down-ice) and thus is an indicator of proximity to a gahnite-bearing bedrock source. Ore (Cu, Pb, Zn, Ag) and pathfinder element (As, Cd, Bi, Hg, In, Sb, Sb, Tl) contents in the &lt;0.063 mm fraction of till reflect glacial dispersal up to a maximum of 6 km down-ice. A 15–20 km till indicator mineral sample spacing is sufficient to detect a gahnite glacial dispersal train such as that from the Izok Lake VMS deposit.

A non-hydrostatic numerical scheme for dispersive waves generated by bottom motion

A numerical scheme based on the staggered finite volume method is presented at the aim of studying surface waves generated by a bottom motion. We address the 2D Euler equations in which the vertical domain is resolved only by one layer. The resulting non-hydrostatic scheme is used to simulate surface waves generated by bottom motion in a water tank. Here we mimic Hammack experiments numerically, in which a bed section is moved upwards or downwards, resulting in transient dispersive waves. For an impulsive downward bottom thrust, free surface responds in terms of a negative leading wave, followed with dispersive train of waves. For an upward bottom thrust, amplitude of the leading wave decays as the wave propagates, and no wave of permanent form evolves— instead, there appears a train of solitons. In this article, we show that our numerical scheme can produce the correct wave profiles, comparable with the analytical and experimental results of Hammack. Simulations using intermediate and slow bottom motions are also presented. In addition, we perform a simulation of a wave generated by submerged landslide, that compares well against previous numerical simulations. Via this simulation, we demonstrate that our scheme can incorporate a moving wet–dry boundary algorithm in the run-up simulation.

Regional and local ice-flow history in the vicinity of the Izok Lake Zn–Cu–Pb–Ag deposit, Nunavut

Ice-directional indicators were compiled from detailed field mapping at the Izok Lake volcanogenic massive sulphide deposit, in the Point Lake region of western Nunavut and eastern Northwest Territories. Cross-cutting erosional relationships and depositional landforms indicate that the Izok Lake area was affected by four ice-flow phases. It is this new glacial history interpretation that is used to explain the gahnite indicator mineral dispersal train down-ice of the Izok Lake deposit as being the net effect of all ice-flow phases. Its fan-shaped morphology is a function of the duration and intensity of two dominant glacial trajectories. Field-based mapping of all glacial-flow indicators are essential, and must be properly interpreted, to detect palimpsest dispersal trains. The resultant dispersal fan serves as a model for future exploration in the glaciated terrain of the north-central part of the Slave Province.

Gold in the sulfide waste-peat bog system as a behavior model in geological processes

Mineral processing wastes may be considered as a natural experimental laboratory for study of mineral� ogical and geochemical peculiarities of rocks and ores changes, forms of elements transport and precipita� tion. Wastes often contain significant amounts of valu� able components including precious metals, which are mobilized into solution, are removed beyond tailing pit, and are reprecipitated on different geochemical barriers in the exogenic process. Carbonaceous mate� rial is one of the most effective geochemical barriers accumulating many elements. Coal [1] and black shale [2] are often considered. Peat and peat bog deposits may be active concentrators of different elements as well, but direct estimation of their role in accumula� tion of precious metals is practically nonexistent. This study is aimed at investigation of gold redistribution and its speciation in peat contacting with acid mine drainage solutions formed by interaction of surface waters with mineral processing wastes of the Ursk ore field in the example of the Ursk tailing pit (Kemerovo region, Russia). The Ursk tailing pit, constructed for more than 80 years ago, is composed by the cyaniding wastes of primary auriferous polymetallic, pyrite ores, and that of the oxidation zone of the New Ursk deposit forming two piles with a height of 10–12 m [3, 4]. The average Au content in primary ores reached 4 ppm. During the whole period of tailing pit existence, the unfixed mate� rial of wastes has been washed out by rainfalls and flood waters. The natural creek draining waste piles has been evolving into acid [4]. Wetland with peat bog located downstream of the tailing pit is burned by acid mine drainage solutions and is covered by the trans� ported wastes layer up to 50 cm through to the Ur River (Fig. 1). Remains of swampy tussocks rise above wastes surface. Based on granulometric differentiation of the transported wastes material, three areas were distinguished in a dispersion trains of the tailing pit

Genesis of dispersal plumes in till

In regions formerly covered by continental ice, till sheets may contain distinctive clastic particles derived from local bedrock sources such as ore bodies. Such particles, especially in thicker tills, may be distributed in three-dimensional dispersal trains or plumes. Developments in our understanding of glacial erosion, entrainment, and deposition over the past two or three decades help clarify formation of these plumes. Much of the debris in the basal ice of ice sheets is likely incorporated at places where water is freezing onto the base of the ice sheet. This water, largely a product of melting of basal ice further upglacier, has migrated downglacier under the influence of a gradient in the hydraulic potential controlled primarily by the ice surface slope and secondarily by basal topography and thermal regime. Refreezing occurs over a substantial distance along flow, so as the ice moves away from an ore body, material eroded from the body is later elevated above the bed by refreezing of more meltwater, incorporating additional material derived from the country rock. Broadening and mixing of the plume, both vertically and horizontally, can occur by shear in the ice, by shifting ice flow directions, by collisions between particles, and by folding of basal ice layers. Further downflow, where net basal melting resumes, the debris is deposited by meltout or lodgement. Many idiosyncrasies of dispersal plumes are likely caused by non-steady-state changes in basal thermal regime.

Glacial dispersal and mode of occurrence of metals in till and esker gravel at Kumpuselkä, northern Finland

A Cu-Zn-Pb-Au mineralized quartz-carbonate vein within micaceous schist recently exposed in a gravel pit quarried into the Kumpuselkä esker (Finland) was the impetus of this study, which examines the glacial dispersal of metals in the nearby Quaternary deposits. The oldest ice flow direction in the area was to the SE–SSE, the younger flow in the ice lobe phase to the ESE and the youngest flow to the ENE. Five till and three esker gravel samples were taken for geochemical and heavy mineral studies. The concentrations of base metals in the conventional fine fraction analysis of the till samples are at background level although the samples had been taken from the very proximal part of the glacial dispersal train. Copper and Pb contents in the fine fraction of esker gravel are at higher levels than those in till fines. Base metal sulphides as chalcopyrite, sphalerite, galena and pyrite were found as some separate grains in the heavy mineral concentrates of till. More often, the Cu, Zn and Pb sulphides occur as tiny inclusions in the coarse pyrite grains. Heavy mineral concentrates of the esker gravel contain abundant pyrite grains, but no visible Cu, Zn or Pb sulphides were recovered. In one heavy mineral concentrate of till (KUM 4), Ni-bearing cobaltite and Co-bearing arsenopyrite along with pyrite, chalcopyrite and sphalerite were found. Sulphide minerals have survived even within the upper C-horizon of the till above the groundwater level and therefore sulphide minerals can be used for prospecting sulphide ores by indicator mineral methods. Some chromite grains were also found in the heavy mineral concentrates of the till samples. Their presence reflects multi-phase, long-distance glacial transport (100 km) of the older till material which have subsequently been inherited by the younger till.

Mercury species in solid matter of dispersion of the Ursk tailing dispersion train (Ursk village, Kemerovo region, Russia)

Mercury species are highly toxic, and methylmercury is the most dangerous for environment and biota. The purpose of this study is to evaluate the distribution of mercury speciations (HgX2 (were X is O, SO2 4- , Cl and et al.), CH3Hg + , HgS) in diffuse halation high-sulfide waste of piles at the Ursk massive sulfide ore deposits which are being mined since the 1940s. To determine the mercury speciation, the method of thermal analysis with atomic absorption spectrometry as detector was applied.