geochemistry of major and trace elements and pb sr isotopes of a weathering profile developed on the lower cambrian black shales in central hunan china abstract this paper reports a geochemical study on the major and trace elements and pb sr isotopes of a weathering profile developed in the lower cambrian black shales in central hunan china six weathering horizons were identified and sampled vertically throughout the profile the chemical composition of the profile consists of variable concentrations of the major elements fe2o3 feo mno mgo cao na2o and p2o5 and of less variable concentrations of sio2 tio2 al2o3 and k2o the chemical change caused by weathering is estimated by mass balance calculations and the results show that the element mobility is characterised by substantial loss of sio2 feo cao k2o na2o loi cr v ba cs rb sr u and th and moderate loss of al2o3 mgo fe2o3 ni cu pb tl sn sc ge and ree y the high field strength elements tio2 sn sc u ga ge zr hf nb and ta were immobile during weathering the chemical changes and the pb sr isotopic data suggest that four types of chemical reactions occurred the oxidation of sulphide minerals e g pyrite and organic carbon os the dissolution of less resistant clinochlore ia calcite and p bearing minerals dl the dissolution of detrital albite and microcline da and the transformation of clay tc minerals e g muscovite and illite smectite these chemical reactions then led to two stages of geochemical processes an early stage of chemical differentiation and a later stage of chemical homogenisation the chemical differentiation dominated by the os dl and da reactions led to the leaching of mobile elements e g mgo na2o k2o p2o5 sr and ree and the redistribution of some less mobile elements e g sio2 and al2o3 in contrast the chemical homogenisation which was caused by tc reactions led to the leaching of both mobile and less mobile elements from the system and ultimately transformed the weathered black shales into soil soils derived from black shales in south china might result from the above two geochemical processes

petrographic and geochemical composition of kerogen in the furongian u cambrian alum shale central sweden reflections on the petroleum generation potential abstract this paper presents an integrated geochemical and petrological study of the hallekis 1 core from the furongian upper cambrian alum shales in central sweden to characterise organic matter composition depositional environment and potential hydrocarbon generation capability the results show that organic rich alum shale toc 8 9 28 0 wt contains mainly immature predominantly algal derived kerogen with unusually reduced hydrocarbon generation potential as suggested by relatively low hydrogen index hi values hi 251 471 mg hc g toc and high degree of aromaticity in the absence of thermal generation of hydrocarbons in these immature shales the recorded low hi values are explained by an unusual chemistry of the biota during the deposition of the alum shale accentuated by a high degree of sustained bacterially mediated degradation e g sulphate reduction and possibly intense nuclear degradation of labile kerogen by radiation from uranium rich minerals the higher degree of aromaticity in alum shale suggests lower than expected oil proneness the results of this study suggest that the alum shale is a gas prone source producing aromatic hydrocarbon mixtures with an unexpectedly low concentration of n alkanes

release of heavy metals during weathering of the lower cambrian black shales in western hunan china weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed heavy metal release during weathering of the lower cambrian black shales lcbs in western hunan china was investigated using traditional geochemical methods and the icp ms analytical technique concentrations of 16 heavy metals 8 trace elements and p were measured for samples from selected weathering profiles at the taiping vanadium ore mine tp the matian phosphorous ore mine mt and taojiang stone coal mine tj the results show that the bedrock at these three profiles is enriched with sc v cr co ni cu zn pb th u mo cd sb tl and p based on mass balance calculation the percentages of heavy metals released in loss relative to immobile element nb were estimated the results show significant rates of release during weathering of v cr co ni cu zn u mo cd sn sb and tl for the tp profile sc cr mn co ni cu zn pb th cd and sn for the mt profile and sc mn co ni zn th cd sn and tl for the tj profile among these heavy metals co ni zn cd and sn show very similar features of release from each of the three weathering profiles the heavy metals released during weathering may affect the environment especially topsoil and surface waters and are possibly related to an observed high incidence of endemic diseases in the area

new understandings of ni mo mineralization in early cambrian black shales of south china constraints from variations in organic matter in metallic and non metallic intervals abstract the well known ni mo ores hosted in early cambrian black shales of south china are one of the research highlights in economic geology for the past few decades however their origin is complex and still debated here based on a case study in the huangjiawan ore of zunyi city guizhou province we generate several new understandings regarding ni mo mineralization through a comparative investigation of organic matter in metallic and non metallic stratigraphic intervals including abundance type maturity and relationship to mineralization we find new direct evidence for biotic impacts on mineralization organic matter and rhodophyte cystocarps red algae in particular may be significantly correlated to mineralization as it accumulates mineralized ni and mo however this organic material as well as disseminated and amorphous organic matters is not the sole and predominant factor controlling mineralization as implied from the nonlinear correlation between organic matter abundance maturation and mineralization other fluid sources e g hydrothermal and or seawater also contribute to mineralization which may be influenced by hydrothermal activity ni and mo may have mineralized independently as suggested by their differential accumulation in different structures of the cystocarps different relationships between organic matter abundance and thermal maturation and mineralized element concentration as well as the large variation in element accumulation coefficients the history of mineralization is complex as ni and mo may be or not be deposited together during the same stage of mineralization these results might also have broader implications for understanding the origin of sediment hosted ores worldwide

atmospheric weathering of scandinavian alum shales and the fractionation of c n and s isotopes abstract subaerial exposure and oxidation of organic carbon c org rich rocks is believed to be a key mechanism for the recycling of buried c and s back to earth s surface importantly processes coupled to microbial c org oxidation are expected to shift new biomass 13 c org composition towards more negative values relative to source however there is scarcity of information directly relating rock chemistry to oxidative weathering and shifting 13 c org at the rock atmosphere interface this is particularly pertinent to the sulfidic c org rich alum shale units of the baltoscandian basin believed to constitute a strong source of metal contaminants to the natural environment following subaerial exposure and weathering consistent with independent support we show that atmospheric oxidation of the sulfidic c org rich alum shale sequence of the cambrian devonian baltoscandian basin induces intense acid rock drainage at the expense of progressive oxidation of fe sulfides sulfide oxidation takes priority over microbial organic matter decomposition enabling quantitative massive erosion of c org without producing a 13 c shift between acid rock drainage precipitates and shale moreover 13 c enrichment in inorganic carbon of precipitates does not support microbial c org oxidation as the predominant mechanism of rock weathering upon exposure instead a 34 s 34 s shale 34 s precipitates 0 accompanied by elevated s levels and the ubiquitous deposition of acid rock drainage sulfate minerals in deposited efflorescent precipitates relative to shales provide strong evidence for quantitative mass oxidation of shale sulfide minerals as the source of acidity for chemical weathering slight 15 n depletion in the new surface precipitates relative to shale coincides with dramatic loss of n from shales collectively the results point to pyrite oxidation as a major driver of alum black shale weathering at the rock atmosphere interface indicating that quantitative mass release of c org n s and key metals to the environment is a response to intense sulfide oxidation consequently large scale acidic weathering of the sulfide rich alum shale units is suggested to influence the fate and redistribution of the isotopes of c n and s from shale to the immediate environment

arsenic in bedrock soil and groundwater the first arsenic guidelines for aggregate production established in finland abstract concern over arsenic as rich drinking water has gained worldwide attention since the 1990s when the problem was discovered in west bengal in india and in bangladesh since then authorities and research institutes have focused on risk assessment and management for as in finland nationwide geochemical mapping projects determined background levels and revealed regions with a higher than average as content in bedrock and soil approximately 10 of the citizens in finland use drinking water from private wells groundwater especially from drilled bedrock wells may contain as concentrations higher than 10 g l the european union quality guideline for as in drinking water here we present the outcome of two european union projects ramas and asrocks which based their conclusions on nationwide databases and thousands of samples both ramas and asrocks focused on the tampere hame region of southern finland where bedrock and soil contain more as than in other parts of finland on average over 1000 groundwater samples revealed that drilled bedrock wells may contain as rich water in certain geological units naturally occurring as in bedrock and soil may also cause the mobilization of as during rock aggregate production and construction activities potentially impacting on groundwater aquifers surface waters and biota arsenic concentrations in aggregate production and construction exceeded the regional background levels in some bedrock and aggregate product samples but during leaching tests as concentrations were found to be low based on the results risk management tools were revised and guidelines for the rock aggregate industry were established in cooperation with authorities companies and other stakeholders to our knowledge the guidelines established were the first in the world the guidelines for as for the aggregate and construction industries can be applied in other countries and adapted to local conditions

influence of palaeoweathering on trace metal concentrations and environmental proxies in black shales the mineralogical and chemical compositions of lower carboniferous tournaisian marine black shale from the kowala quarry the holy cross mountains poland were investigated this study focuses on disturbances in palaeoenvironmental proxies caused by palaeoweathering which progressively changed the major and trace element abundances palaeomagnetic investigations reveal that the devonian carboniferous succession was weathered during the permian triassic by the infiltration of oxidizing fluids related to karstification following post variscan exhumation the weathering process led to vermiculitization of chlorite partial dissolution of calcite and replacement of pyrite by hematite and goethite moreover the concentrations of some trace metals including co cu pb mo ni as and u significantly decreased consequently some elemental abundance ratios that are used as environmental proxies including u th ni co and v cr were altered elements that are bound to iron sulphides e g mo appear to be especially prone to mobilization by even a lightly weathered black shale the documented weathering including changes in elemental concentrations can potentially create misinterpretations of the original palaeoenvironmental conditions in addition the palaeoweathering of the studied samples appears to have substantially changed the carbon oxygen nitrogen and molybdenum stable isotope values the nitrogen and molybdenum stable isotope ratios in particular appear to be most sensitive to the effects of weathering and therefore are good indicators of palaeo weathering processes the major cause of these changes is the decay of organic matter and pyrite for the organic carbon stable isotopes ratios the main factor that controlls this process appears to be the preferential degradation of labile organic matter a combination of the total organic carbon toc total sulphur ts content mo concentration and stable isotope compositions seems to be the most useful for identify palaeo weathering our results suggest that reductions in ts and mo in tandem with diminished mo stable isotope values in the absence of obvious changes to the toc content provide the most compelling evidence of palaeo weathering

karelian shungite an indication of 2 0 ga old metamorphosed oil shale and generation of petroleum geology lithology and geochemistry abstract the ca 2 0 ga old 600 m thick upper zaonezhskaya formation near lake onega nw russia contains unusually high concentrations of corg up to 98 averaging around 25 the formation contains an estimated 25 1010 tonnes of organic carbon accumulated within an area of 9000 km2 organic material is represented by shungite which forms a black dense amorphous or nanocrystalline mass consisting of c with traces of n o s and h autochthonous shungite occurs as disseminated organic material 0 1 50 corg which when mixed with migrated bitumen now pyrobitumen appears as coal like seams and lenses of semilustrous and semimat layer shungite rocks oil shales 50 75 corg the migrated bitumen originally petroleum represented by the lustrous vein and layer shungite conformably fills interbedding spaces or cross cutting joints and usually contains 80 98 corg the shungite bearing rocks of the upper zaonezhskaya formation represent one of the most richest accumulations of organic material reported from the palaeoproterozoic and one of the geologically earliest stages of petroleum generation the sediments of the zaonezhskaya formation were initially deposited in brackish water in a non euxinic lagoonal environment the high c s ratio 8 1000 with a zero intercept on the c s cross plot indicates that deposition occurred in sulphur poor water intensive synchronous volcanism may have contributed to both the enhanced delivery of nutrients and elevated sedimentation rate and eventually to the high degree of preservation of organic material the integrated data suggest that the organic material has a biogenic origin most likely algal or bacterial the organic material suffered complex catagenetic and metamorphic alteration which is reflected in 1 the four modal distribution of corg content with maxima at 5 30 65 and 95 2 highly variable 13 c org 45 to 17 3 bimodal distribution of 13 c org with maxima at 28 and 39 and 4 low h c ratios 0 005 0 2 abundant diagenetic carbonates associated with shungite rocks 13 c carb 5 to 26 and the presence of pyrite 34 s 22 to 31 reflects substantial loss of organic matter via bacterial reduction of sulphate during diagenesis the shungite rocks are characterised by a further substantial loss 50 of biologically produced organic material in the course of thermal maturation and by a depletion in 12 c 10 the isotopic composition of carbonate concretions does not indicate the involvement of fermentative diagenesis conservative estimates give 13corg of 34 as the best value of the initial biomass lustrous vein and layer shungite containing more than 80 corg are considered to be allochthonous migrated bitumen originally petroleum the semilustrous and semimat layer shungite rocks containing 55 75 corg represent oil shales with both migrated bitumen originally petroleum and autochthonous kerogen residues the oil source rocks were apparently hosted in the zaonezhskaya formation the generated oil has migrated both vertically and laterally with the highest concentration in cupola structures the locality at shunga represents the most significant volume of trapped petroleum from the study area

uranium mineralization in the alum shale formation sweden evolution of a u rich marine black shale from sedimentation to metamorphism the alum shale formation is a metal rich black shale deposited on the baltoscandian platform between middle cambrian and early ordovician these black shales may be of particular economic interest for their relatively high uranium content 100 300 ppm and their wide distribution from norway to estonia scandinavian alum shale may thus constitute a great potential resource of uranium as a low grade ore the alum shale formation is particularly interesting to study the mineralogical expression and content of uranium in series submitted to progressive burial and metamorphism for this purpose the behavior of u p ti and organic matter was studied on a series of representative samples from most alum shale prospection zones in southern sweden where alum shale underwent fairly shallow burial uranium concentrations have no mineralogical expression except a rather high u content of biogenic phosphates calcite concretions beefs and fractures recorded the migration of hot overpressured hydrocarbons and brines from thermally mature areas to immature alum shale however thermal maturation and fluid migration did not allow remobilization of uranium and metals at the opposite in northern sweden where the series were folded duplicated and submitted to low grade greenschist metamorphism during caledonian orogeny phospho silicates u si ca p ti zr y and minor amounts of uraninite are identified and indicate that u p and ti were mobile and precipitated as new phases the effect of metamorphism is therefore important to consider as the leachability of u especially during bio hydrometallurgical processes which will be by far different between the two considered areas

mercury bearing black shales and human hg intake in eastern finland impact and mechanisms migration of hg from black shales to the aquatic ecosystems and local residents was studied comprehensively with samples of black shales 627 samples surface waters 22 organic stream sediments 40 organic lake sediments 172 noble crayfish 72 and human hair 225 the black shales exhibited elevated c s ni cu zn cd and hg concentrations gneiss granite mica schist and quartzite with very low heavy metal contents are encountered just next to the black shales offering good reference areas for comparison there are no local anthropogenic hg sources in the study areas black shale areas were reflected as elevated ni cu zn and cd and low ca in glacial till surface waters organic stream sediments and lake sediments mercury behaved differently in surface waters than the other heavy metals there was no correlation between the hg concentration of the surface waters and the hg concentration of the underlying bedrock median values for total hg and methyl hg in stream water were 1 6 and 0 2 ng l respectively in the black shale area and 2 0 and 0 3 ng l in the adjacent reference area with hg poor bedrock even though hg concentrations in surface waters were not elevated in the black shale areas relative to the reference areas mean hg concentrations of the muscle of noble crayfish astacus astacus were higher in black shale area lakes than in lakes in the reference areas the explanation of this correlation probably is not hg flux from the bedrock to watercourses as a more easily eroded rock than granites quartzites and mica schists black shale tends to occur in topographic depressions in glaciated terrain lakes in the black shale areas are typically surrounded by peatlands and the catchment areas from which they collect humic material rich in hg may be extensive the total hg concentrations in hair ranged from 0 04 to 12 1 g g the distribution of hair hg content did not appear to correlate with the distribution of black shales in the present study the main route of hg to humans was via fish even though hg contents were higher in crayfish and fish in the black shale area lakes people consumed fish not only from the lakes next to their residence but also from lakes situated in the reference areas among the non fish eaters in one black shale area the use of dug well water as well as the consumption of local potatoes and mushrooms slightly increased the hg in hair this contribution may reflect the heavy metal load of the natural black shale environment

depositional setting of the 2 1 ga francevillian macrobiota gabon rapid mud settling in a shallow basin swept by high density sand flows the depositional setting of the 2 1 ga fill to the franceville basin of gabon is important for understanding the habitat energy and availability of light and oxygen and taphonomy of recently discovered early macro organisms buried in black shales in unit fb the available data bearing on the stratigraphy and sedimentology of unit fb provide new insight into processes acting on the palaeo seafloor the shales are interpreted to have formed as fluid mud deposits interstratified with structureless sands the latter poubara sandstones were emplaced during a forced regression during the terminal infill of fault bounded sub basins following a stage characterised by a ferruginous to anoxic water column the structureless sandstones were deposited from high density gravity currents along with a locally strong bottom oscillation of the water column tuft structures preserved in cyanobacterial mats together with the position of the macro organisms at the top of the sandstone beds within associated black shales point to a water depth of less than 80 m the relative sea level fall that drove deposition of the poubara sandstones controlled the rise of a phototrophic ecosystem and also possibly favoured the supply of oxygen and nutrients via density flows this article is protected by copyright all rights reserved

the 28 october 1996 landslide and analysis of the stability of the current huashiban slope at the liangjiaren hydropower station southwest china on 28 october 1996 a landslide occurred on the huashiban slope near the liangjiaren hydropower station the landslide was caused by a failure mechanism induced by an earthquake mw 7 0 at lijiang on 3 february 1996 after which a tensile fracture zone formed on the huashiban slope the subsequent impact of several small earthquakes on the slope increased the tension crack connectivity and the tensile strength gradually decreased severe rainfall in the rainy season between may and october especially in july and august decreased the shear strength of the bottom sliding surface resulting in a landslide on the huashiban slope on 28 october 1996 the stability of the huashiban slope is important for plant site selection if a further landslide occurs on the slope the liangjiaren hydropower station project will be critically affected so analysis of the current slope stability is extremely important at present the huashiban slope can be divided into five subzones 1 a landslide deposit zone 2 a landslide zone 3 a tensile fracture zone 4 a crescent shaped zone and 5 an upper slide zone using historic landslide data for 28 october 1996 retrospective analysis of the landslide process revealed shear strength parameters for the huashiban slope the cohesion strength is 0 024 mpa the friction angle at the bottom sliding surface is 14 and the tension crack connectivity is 50 these parameters were used to compute the stability of the huashiban slope under the same conditions the stability of the whole slope is better than that of part of the slope and the overall stability is dominated by the tensile fracture zone under earthquake and rainfall conditions it is possible that failure will occur in the tensile fracture zone thus the huashiban slope should be reinforced for construction and operation of the liangjiaren hydropower station

geochemistry of soils derived from black shales in the ganziping mine area western hunan china the geochemistry of major and trace elements including heavy metals and rare earth elements of the fresh and weathered black shales and the soils derived from black shales in the ganziping mine area in western hunan province china were studied using the following techniques x ray fluorescence xrf inductively coupled plasma mass spectrometer icp ms and x ray diffraction xrd the results show that the black shale soils are significantly enriched with al2o3 and fe2o3 and depleted of mobile elements cao na2o and k2o the soils are also highly enriched with heavy metals u v ni ba cu zn and pb that may cause potential heavy metal contamination of the soils composition of the soils is homogeneous compared to the weathered black shales for which the concentrations of major elements except cao and na2o and trace elements except heavy metals u v ni ba cu zn and pb as well as the mobile sr show lower variations than in the weathered black shales ratios of zr hf ta nb y ho nd sm and ti ti zr of the soils are also less variable with values constantly similar to that of the fresh and weathered black shales correspondingly thus components of the soils are believed to be contributed from the parent black shales through weathering and pedogenesis it is concluded that the soils were formed by at least two stages of geochemical processes the early stage of chemical differentiation and the later stage of chemical homogenization the chemical differentiation that was taken during black shale weathering might have caused the depletion of cao and na2o and the enrichment of al2o3 and fe2o3 while the chemical homogenization that was taken during pedogenesis led to the depletion of sio2 and k2o and to the further enrichment of al2o3 and fe2o3 the heavy metal enrichment contamination of the soils was then genetically related to the enrichment of al2o3 and fe2o3 in the soils

geochemistry and origin of tin polymetallic sulfide deposits hosted by the devonian black shale series near dachang guangxi china abstract two tin polymetallic sulfide deposits hosted by the devonian black shale series of the guangxi zhuang autonomous region occur in the dachang ore field the upper devonian frasnian epoch black shale series contains the giant tongkeng changpo deposit and the middle devonian givetian epoch reef limestone contains the giant longtoushan deposit intrusive rocks occur at lame and the western part of dachang ores occur as stratified bodies large veins stockworks and zones of veinlets ores are massive banded laminated and disseminated the ores contain more than 180 different minerals the most important of which are cassiterite sulfides and sulfosalts primary laminated sedimentary sulfide ores occur at tongkeng the mean ratio of sio 2 al 2 o 3 for shale marl is 3 5 but values averaging 56 and 67 respectively for ore and chert suggest a biogenic or hydrothermal source for silica ores and country rocks are rich in sb pb zn sn and cu granites are rich in sb w zn and sn dispersed elements such as te cd se and in are abundant in ores country rocks and granites implying contributions of sedimentary and intrusive activities to the ore formation mean y ho values for the black shale series 28 and granite 31 are similar to most shales and most volcanic rocks the y ho value for reef limestone is 47 comparable to sea water devonian black shale series are slightly lree enriched on chondrite normalized plots and show small negative eu anomalies mean eu 0 56 ce 0 9 and ce anom 0 07 values suggest a shallow water deposition near the redox boundary the 34 s values of sulfides from various deposits of dachang vary with the 34 s values for lame ranging from 2 to 2 and values for tongkeng changpo ranging from 4 9 to 2 6 the highly negative 34 s values 9 5 to 11 3 of huile and kengma sulfides suggest the important role of biogenic sulfur the mean 13 c value of organic matter of devonian black shale series is 24 6 the 30 si nbs 28 values of upper devonian black chert are 0 2 0 3 indicating a sedimentary origin the dachang black chert has been dated at 124 2 ma that of luofu section at 387 18 ma implying that the rb sr isotope of dachang chert was reset during yanshan movement these results suggest that the dachang tin polymetallic sulfide deposits exemplify strongly remobilized sedimentary mineralization

seismically induced rock slope failures resulting from topographic amplification of strong ground motions the case of pacoima canyon california abstract the 1994 northridge earthquake mw 6 7 triggered extensive rock slope failures in pacoima canyon immediately north of los angeles california pacoima canyon is a narrow and steep canyon incised in gneissic and granitic rocks peak accelerations of nearly 1 6 g were recorded at a ridge that forms the left abutment of pacoima dam peak accelerations at the bottom of the canyon were less than 0 5 g suggesting the occurrence of topographic amplification topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 mw 6 7 san fernando earthquake furthermore high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones we conducted field investigations and slope stability back analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions which would have generated a significantly lower number of areas affected by landslides in contrast modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994 this observation confirms a significant role for topographic amplification on the triggering of landslides at the site and emphasises the need to select carefully the inputs for seismic slope stability analyses

origin of proterozoic metal rich black shales from the bohemian massif czech republic proterozoic metal rich black shales metasiltstones in the bohemian massif are always closely associated with submarine mafic volcanic rocks and occur in semi isolated basins that formed most likely in connection with the evolution of an upper proterozoic intracontinental rift the black shales are characterized by an average of 3 5 wt percent c organic and 5 2 wt percent s and carry up to 0 42 wt percent zn 0 21 wt percent v 0 12 wt percent ni 0 12 wt percent cr 0 12 wt percent cu 0 06 wt percent as 0 03 wt percent mo 132 ppb au 102 ppb pd 25 ppb pt 1 7 ppb rh and 1 3 ppb ru their thickness varies from about 1 to 45 m sulfide minerals often include abundant framboidal pyrite which occurs widely in c organic rich layers grainy pyrite zn ni cu and mo sulfides appear to be restricted to late quartz and carbonate veinlets mo selenide mo telluride galena berthierite and gold are very rare sulfur isotope results suggest the dominant source of sulfur to have been seawater sulfate reduced by bacteria under different conditions the delta 13 c values of the organic matter 24 2 to 37 5ppm reflect the combination of the carbon isotope composition of dissolved hco 3 its high concentration and the type of organisms the results of rock eval pyrolysis as well as laser raman spectroscopy show a high maturity close to that of well crystallized graphite fluid inclusion and stable isotope data from quartz and carbonate veinlets of very low grade regionally metamorphosed metalrich black shales at kamenec and highly metamorphosed facies at hromnice indicate that they resulted from the interaction between 18 o rich fluids volcanics and metasediments the interaction could have occurred during subsea floor or later regional metamorphism

hydrogeochemical processes governing the origin transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters abstract the formation of acid mine drainage from metals extraction or natural acid rock drainage and its mixing with surface waters is a complex process that depends on petrology and mineralogy structural geology geomorphology surface water hydrology hydrogeology climatology microbiology chemistry and mining and mineral processing history the concentrations of metals metalloids acidity alkalinity cl f and so 4 2 found in receiving streams rivers and lakes are affected by all of these factors and their interactions remediation of mine sites is an engineering concern but to design a remediation plan without understanding the hydrogeochemical processes of contaminant mobilization can lead to ineffective and excessively costly remediation furthermore remediation needs a goal commensurate with natural background conditions rather than water quality standards that might bear little relation to conditions of a highly mineralized terrain this paper reviews hydrogeochemical generalizations primarily from us geological survey research that enhance our understanding of the origin transport and fate of contaminants released from mined and mineralized areas mobility of potential or actual contaminants from mining and mineral processing activities depends on 1 occurrence is the mineral source of the contaminant actually present 2 abundance is the mineral present in sufficient quantity to make a difference 3 reactivity what are the energetics rates and mechanisms of sorption and mineral dissolution and precipitation relative to the flow rate of the water and 4 hydrology what are the main flow paths for contaminated water estimates of relative proportions of minerals dissolved and precipitated can be made with mass balance calculations if minerals and water compositions along a flow path are known combined with discharge these mass balance estimates quantify the actual weathering rate of pyrite mineralization in the environment and compare reasonably well with laboratory rates of pyrite oxidation except when large quantities of soluble salts and evaporated mine waters have accumulated underground quantitative mineralogy with trace element compositions can substantially improve the identification of source minerals for specific trace elements through mass balances post dissolution sorption and precipitation attenuation reactions depend on the chemical behavior of each element solution composition and ph aqueous speciation temperature and contact time with mineral surfaces for example little metal attenuation occurs in waters of low ph

extreme enrichment of polymetallic ni mo pge au in lower cambrian black shales of south china an os isotope and pge geochemical investigation extreme metal enrichments occur in the lower cambrian niutitang formation a thick black shale sequence deposited on the yangtze platform of south china and form a regionally distributed conformable polymetallic ni mo pge au sulfide horizon the origin for the extreme enrichment of metals in these black shales is discussed based on a comprehensive geochemical investigation of re os isotopes and platinum group elements the black shales of the lower cambrian niutitang formation in guizhou province yielded an re os isochron age of 535 11 ma with an initial 187 os 188 os ratio of 0 80 0 04 which is similar to the initial 187 os 188 os ratio 0 78 0 19 of the ni mo sulfide ores but slightly lower than the initial 187 os 188 os ratio 1 18 0 02 of lower cambrian black shales from the lesser himalaya india a comparison of os isotope data among the chinese ni mo sulfide ores the seafloor massive sulfide deposits and contemporaneous seawater suggests a possible similar hydrothermal forming mechanism for these deposits the pge concentrations pt anomaly pt pt pt pd ir pd au pd ratios of the chinese ni mo sulfide ores are similar to those metal rich black shales of submarine volcanogenic hydrothermal origin from czech republic namibia and canada but are different from those data of the ocean floor fe mn crusts that have scavenged their pge and other metals directly from seawater it is therefore suggested that the ni mo sulfide ores from the niutitang black shale sequence in south china had a submarine hydrothermal origin the anoxic environments and abundant organic matter in the ocean basin also played a key role for the extreme metal enrichments the discharge of hydrothermal fluids into the cambrian ocean may have had a great effect on life during the cambrian explosion 2007 elsevier b v all rights reserved

base metal rich metamorphosed black shales associated with proterozoic ophiolites in the kainuu schist belt finland a genetic link with the outokumpu rock assemblage metamorphosed black shale is an essential component of the early proterozoic outokumpu rock assemblage together with serpentinite calc silicate rock and quartz rock this rock assemblage hosting the major cu co zn deposits of outokumpu and considered ophiolitic in origin has also been encountered to the northwest in the kainuu schist belt the rift basin encompassing the two areas was intruded by ophiolite complexes 1 96 1 97 billion years ago remnants of ultramafites are met as serpentinite and talc carbonate rock lenses bounded by faults along the western margin of the kainuu schist belt the black schist formations range in thickness from tens of metres to 400 m metal rich layers occur close to the serpentinite bodies the most extensive formations of metal rich black schist 300 mt 0 26 ni 0 14 cu 0 53 zn have been encountered at talvivaara the lithological mineralogical and geochemical results indicate a genetic link between the jormua talvivaara alanen and pappilanmaki prospects in the kainuu schist belt and the outokumpu rock assemblage

geology of the enterprise hydrothermal nickel deposit north western province zambia the enterprise nickel deposit 40 mt of 1 07 ni is located on the eastern edge of the kabompo dome in the north western province of zambia the deposit area contains basement schists overlain by neoproterozoic metasedimentary rocks nickel sulfides are hosted within a sequence of quartz carbonate and carbon rich metasedimentary rocks that interfinger with and overlie siliciclastic metasedimentary rocks the host rocks contain significant kyanite talc and magnesian chlorite silicification and magnesian metasomatism occurred prior to or concurrent with a regional metamorphic event 590 500 ma mineralization resulted in the precipitation of nickel and iron nickel sulfides in veins and as semimassive replacements of the host rocks nickel sulfides precipitated in two main stages a millerite vaesite pyrite assemblage that formed disseminations and semimassive replacements in vuggy textured rocks and a later millerite bravoite molybdenite assemblage in quartz kyanite veins and local semimassive replacements the deposit contains minor copper and trace amounts of cobalt and platinum group elements pges a discrete zone of copper sulfides underlies a portion of the nickel sulfide zone re os geochronology on molybdenite yields a 540 6 1 8 ma age for mineralization at enterprise the approximate age of metamorphism sulfur isotope results indicate that the sulfur at enterprise was derived largely from neoproterozoic marine sulfate by thermochemical sulfate reduction significant volumes of mafic igneous rocks are not present in the immediate area of the enterprise deposit no evidence of prealteration concentrations of nickel exists within the sedimentary rock sequence at the deposit the alteration and mineralization style of the enterprise deposit is similar to the much less metamorphosed nickel bearing shinkolobwe uranium deposit in the democratic republic of congo drc though the enterprise deposit does not contain significant uranium the sediment hosted nickel rich deposits of central african copperbelt exemplified by enterprise appear to represent a new style of hydrothermal nickel mineralization

origin of the nchanga copper cobalt deposits of the zambian copperbelt the zambian copperbelt forms the southeastern part of the 900 km long neoproterozoic lufilian arc and contains one of the world s largest accumulations of sediment hosted stratiform copper mineralization the nchanga deposit is one of the most significant ore systems in the zambian copperbelt and contains two major economic concentrations of copper and cobalt hosted within the lower roan group of the katangan supergroup a lower orebody copper only and upper orebody copper and cobalt occur towards the top of arkosic units and within the base of overlying shales the sulfide mineralogy includes pyrite bornite chalcopyrite and chalcocite although in the lower orebody sulfide phases are partially or completely replaced by malachite and copper oxides carrollite is the major cobalt bearing phase and is restricted to fault propagation fold zones within a feldspathic arenite hydrothermal alteration minerals include dolomite phlogophite sericite rutile quartz tourmaline and chlorite quartz veins from the mine sequence show halite saturated fluid inclusions ranging from 31 to 38 wt equivalent nacl with homogenisation temperatures thtot ranging between 140 and 180 c diagenetic pyrites in the lower orebody show distinct relatively low 34s ranging from 1 to 17 whereas arenite and shale hosted copper and cobalt sulfides reveal distinctly different 34s from 1 to 12 for the lower orebody and 5 to 18 for the upper orebody there is also a clear distinction between the 34s mean of 12 1 3 3 n 65 for the upper orebody compared with 5 2 3 6 n 23 for the lower orebody the 13c of dolomites from units above the upper orebody give 13c values of 1 4 to 2 5 consistent with marine carbon however dolomite from the shear zones and the alteration assemblages within the upper orebody show more negative 13c values 2 9 to 4 0 and 5 6 to 8 3 respectively similarly shear zone and upper orebody dolomites give a 18o of 11 7 to 16 9 compared to lower roan dolomites which show 18o of 22 4 to 23 0 two distinct structural regimes are recognized in the nchanga area a weakly deformed zone consisting of basement and overlying footwall siliciclastics and a moderate to tightly folded zone of meta sediments of the katangan succession the fold geometry of the lower roan package is controlled by internal thrust fault propagation folds which detach at the top of the lowermost arkose or within the base of the overlying stratigraphy and show vergence towards the ne faulting and folding are considered to be synchronous as folding predominantly occurred at the tips of propagating thrust faults with local thrust breakthrough the data from nchanga suggests a strong link between ore formation and the development of structures during basin inversion as part of the lufilian orogeny sulfides tend to be concentrated within arenites or coarser grained layers within shale units suggesting that host rock porosity and possibly permeability played a role in ore formation however sulfides are also commonly orientated along but not deformed by a tectonic fabric or hosted within small fractures that suggest a significant role for deformation in the development of the mineralization the ore mineralogy hydrothermal alteration and stable isotope data lend support to models consistent with the thermochemical reduction of a sulfate and metal enriched hydrothermal fluid at the site of mineralization there is no evidence at nchanga for a contribution of bacteriogenic sulfide produced during sedimentation or early diagenesis to the ores

evolution of porosity and geochemistry in marcellus formation black shale during weathering abstract soils developed on the oatka creek member of the marcellus formation in huntingdon pennsylvania were analyzed to understand the evolution of black shale matrix porosity and the associated changes in elemental and mineralogical composition during infiltration of water into organic rich shale making the reasonable assumption that soil erosion rates are the same as those measured in a nearby location on a less organic rich shale we suggest that soil production rates have on average been faster for this black shale compared to the gray shale in similar climate settings this difference is attributed to differences in composition both shales are dominantly quartz illite and chlorite but the oatka creek member at this location has more organic matter 1 25 wt organic carbon in rock fragments recovered from the bottom of the auger cores and nearby outcrops and accessory pyrite during weathering the extremely low porosity bedrock slowly disaggregates into shale chips with intergranular pores and fractures some of these pores are either filled with organic matter or air filled but remain unconnected and thus inaccessible to water based on weathering bedrock soil profiles disintegration is initiated with oxidation of pyrite and organic matter which increases the overall porosity and most importantly allows water penetration water infiltration exposes fresh surface area and thus promotes dissolution of plagioclase and clays as these dissolution reactions proceed the porosity in the deepest shale chips recovered from the soil decrease from 9 to 7 while kaolinite and fe oxyhydroxides precipitate eventually near the land surface mineral precipitation is outcompeted by dissolution or particle loss of illite and chlorite and porosity in shale chips increases to 20 as imaged by computed tomographic analysis weathering causes i greater porosity ii greater average length of connected pores and iii a more branched pore network compared to the unweathered sample this work highlights the impact of shale water o 2 interactions in near surface environments 1 black shale weathering is important for global carbon cycles as previously buried organic matter is quickly oxidized and 2 black shales weather more quickly than less organic and sulfide rich shales leading to high porosity and mineral surface areas exposed for clay weathering the fast rates of shale gas exploitation that are ongoing in pennsylvania texas and other regions in the united states may furthermore lead to release of metals to the environment if reactions between water and black shale are accelerated by gas development activities in the subsurface just as they are by low temperature processes in our field study

processes that control mineral and element abundances in shales abstract a shale s composition can be used to infer physical chemical and biological processes that have acted on it over its life history and this knowledge is used to surmise conditions at the time when each process was active this review lists the most important processes that control shale mineral and element abundances during each of the five stages of its life history 1 during weathering transport and deposition the most important processes are chemical weathering hydraulic sorting and mixing adsorption reverse weathering and incorporation of organic matter and biominerals 2 during early diagenesis the most important processes are exchange across the water sediment interface compaction microbial respiration mineral transformations and concretion formation 3 during burial diagenesis the most important processes are compaction catagenesis and metagenesis and mineral transformations 4 during exhumation the most important processes are decompaction brine invasion groundwater penetration and microbial respiration 5 during weathering the most important processes are organic matter oxidation mineral oxidation and hydrolysis groundwater transport and disaggregation this classification of processes provides a way to envision how concurrent and consecutive processes that occurred over a shale s life history have affected its mineralogy and chemical composition

geochemistry of the kupferschiefer poland cu pb and zn are the main metals occurring in sulfides in the kupferschiefer they are arranged in the three distinct zones around rote faule in the order cu pb and zn copper zones are enriched in transition metals i e ag ni co v and mo ranging from 600 to 1500 ppm they are concentrated especially in the bottom part of black shale re is associated with mo the re mo ratio in cu pb and k castaingites is about 1 70 in copper zones near the contact with lead zones au platinum group metals pgm and u are concentrated ranging from traces to several hundred ppm the main mechanism of concentration of transition metals was catalytic autooxidation and dehydrogenation of organic matter the noble metals form either independent minerals or are present in organic matter and thucholite in the lead zones at the contact with cu zones an increased content of ag 100 1500 and hg 5 800 ppm is present the average hg content for the black shale of the zone is 61 ppm a natural gas exploited from the rotliegendes beneath the kupferschiefer carries in aerosols significant amount of pb cu mn fe ag and hg this suggests the rotliegendes as a pathway or as a source of metals for the kupferschiefer the presence of k castaingite intergrown with silvinite kcl may suggest k dominated brines as the mineralizing fluids

acid drainage generation and seasonal recycling in disturbed permafrost near eagle plains northern yukon territory canada abstract acidic so 4 ca fe waters are discharging from sandstone bedrock overlying pyrite rich shales along the dempster highway near eagle plains northern yukon territory although evidence of acid drainage was present prior to the construction of the dempster highway in the 1970 s the removal of surficial sediments during its construction amplified the release of acidity by allowing the active layer to penetrate into the freshly exposed pyrite rich shale acid drainage originating from the excavated area has a ph value averaging 3 1 0 3 and over 5 g l of dissolved solids so 4 2 3915 mg l fe total 459 mg l ca 2 418 mg l and al total 83 6 mg l whereas the unaffected drainage has a ph greater than 4 4 and total dissolved solids in the 100 to 200 mg l range geochemical modeling of the surface waters and active layer pore water using phreeqc hydrogeochemical computer code predicted saturation in fe hydroxide and fe sulfate minerals which is confirmed by the observation of abundant ferrihydrite precipitates along the acidified stream the solute concentrations of the acidified stream and active layer soluble ions versus so 4 plot on very similar slopes suggesting a recycling of solutes it is suggested that the effect of seasonal freeze thaw of the active layer plays an important role in sustaining acidity in the stream freeze back of the acid waters in the active layer produces both fe sulfate minerals and residual sulfuric acid during the thaw season this acidity is released thus enhancing further dissolution of alumino silicate minerals the release of these contaminants including acidity not only causes a perturbation of the water quality but also has a negative impact on the sensitive arctic ecosystem by disturbing the local permafrost conditions

coastal cliff monitoring and analysis of mass wasting processes with the application of terrestrial laser scanning a case study of rugen germany abstract an active landslide affecting a composite sea cliff section of the island of rugen germany was investigated and monitored using terrestrial laser scanning biannual surveys were performed from 2006 to 2011 high resolution scans were used to delineate landslide extensions monitor the spatial and temporal changes and evaluate the processes of mass wasting along the cliff section between may 2006 and may 2011 the multi temporal analysis documents a strong landward progression of the landslide that resulted in an increase in the planimetric area by 32 in the same period 9365 m 3 of soil volume has been removed primarily due to rainfall triggered surface runoff erosion and the resulting slumping this volume loss correlates with the preferential erosion of weak and unconsolidated sediments building up the major part of the cliff face this produced a maximum cliff top retreat of 17 32 m with an average retreat rate of 3 46 m yr 1 the quantification of the mass wasting processes and cliff top retreat demonstrates the substantial effect of local cliff lithology on slope stability and supports a prognosis of the near future development of the landslide furthermore the absence of local wave attack indicators or human activity highlights the major role of subaerial processes in the erosion of the sea cliff these results can be transferred to cliff locations in the urbanised cliff top area nearby that currently suffer similar cliff erosion processes and episodic events of large cliff top retreats the study therefore provides reliable data for the local authorities in charge of hazard assessment and planning and implementation of adaptive countermeasures

arsenic in marine sediments how robust a redox proxy abstract arsenic as is reputed to be a redox sensitive element but has not been fully explored yet as a proxy in marine sediments and sedimentary rocks compared to extensively examined elements such as molybdenum mo and uranium u here the behavior of as is compared to that of mo and u in a number of paleo environmental situations that have been studied before and are therefore rather well constrained the results indicate that attention must be paid to the reference values used to normalize sedimentary as content in geochemical studies the most commonly used references namely the post archean australian shale and average upper crust of earth to be opposed to the average shale tend to overestimate slightly as enrichments as shown by as enrichment factors being quasi systematically larger than 1 whatever the geological setting the results also show that as enrichments are less straightforward compared to those of mo and u when using these elements as redox proxies in addition the depositional milieus that endured the most hydrologically restricted and or reducing euxinic conditions are not those with the highest as enrichments thus arsenic shows a redox sensitive behavior but is not adequate as a redox proxy however as enrichments are correlated with mo enrichments in two distinct types of situations settings impacted 1 by particulate iron shuttling processes and 2 by diagenetic fluid circulation cold seeps in both cases the mo as correlation is induced by the strong relationship between these trace metals and reactive iron fe conveys both as and mo to the sediment where they are trapped thus arsenic has a promising potential to allow recognition of past depositional environments associated with iron shuttling and cold seep circulations lastly high toc high mo low as situations point out possible occurrences of sulfurized organic matter in sediments high mo concentrations indicate reducing sulfidic conditions prone to organic matter accumulation high toc values but low as concentrations indicate that reactive iron was a limiting factor preventing as capture under such conditions free h2s was not associating with iron and could react with organic matter causing its sulfurization

a marine biogeochemical perspective on black shale deposition abstract deposition of marine black shales has commonly been interpreted as having involved a high level of marine phytoplankton production that promoted high settling rates of organic matter through the water column and high burial fluxes on the seafloor or anoxic sulfidic water column conditions that led to high levels of preservation of deposited organic matter or a combination of the two processes here we review the hydrography and the budgets of trace metals and phytoplankton nutrients in two modern marine basins that have permanently anoxic bottom waters this information is then used to hindcast the hydrography and biogeochemical conditions of deposition of a black shale of late jurassic age the kimmeridge clay formation yorkshire england from its trace metal and organic carbon content comparison of the modern and jurassic sediment compositions reveals that the rate of photic zone primary productivity in the kimmeridge sea based on the accumulation rate of the marine fraction of ni was as high as 840 g organic carbon m 2 yr 1 this high level was possibly tied to the maximum rise of sea level during the late jurassic that flooded this and other continents sufficiently to allow major open ocean boundary currents to penetrate into epeiric seas sites of intense upwelling of nutrient enriched seawater would have been transferred from the continental margins their present location onto the continents this global flooding event was likely responsible for deposition of organic matter enriched sediments in other marine basins of this age several of which today host major petroleum source rocks bottom water redox conditions in the kimmeridge sea deduced from the v mo ratio in the marine fraction of the kimmeridge clay formation varied from oxic to anoxic but were predominantly suboxic or denitrifying a high settling flux of organic matter a result of the high primary productivity supported a high rate of bacterial respiration that led to the depletion of o2 in the bottom water a high rate of burial of labile organic matter albeit a low percentage of primary productivity in turn promoted anoxic conditions in the sediment pore waters that enhanced retention of trace metals deposited from the water column

environmental impact of mineralised black shales abstract black shales are sedimentary rocks containing 0 5 of organic carbon they host polymetallic deposits which have been mined for cu ni zn mn p mo v u au and pge platinum group elements even sub economic occurrences provide potential risk of acid rock drainage when exposed to oxic surface environment the natural acid neutralisation potential varies depending on the adjacent rock units especially on the presence of calcareous rocks the chemical and mineralogical composition of black shale is reflected in the quality of the surface waters and groundwater cu ni pb u and zn are recognised as major pollutants though the environmental impact is characteristically polymetallic just like the black shale occurrences hence the environmental impacts have to be evaluated in each occurrence the proterozoic ni zn cu co deposit at talvivaara finland is reviewed in more detail as an example of a large low grade deposit that is currently exploited with open pit mining and a bioleaching process together with the proterozoic central african copperbelt the cambrian u mo deposits in sweden the cambrian ni mo pge deposits in china and the cambrian ordovician u deposits in south korea the devonian ni zn pge occurrences in yukon canada and kentucky usa and the permian cu ag deposits in poland and germany the mineralised horizons may be merely few centimetres thick like in yukon or hundreds of metres thick like at talvivaara both natural and anthropogenic environmental impacts of black shales are reviewed world wide and based on the overview of the state of the art an integrated research approach is suggested for the comprehensive assessment of the risk black shales are natural sources of soil and water contamination at talvivaara the geochemical background includes higher than average concentrations of ni cu zn and mn in glacial till peat surface waters and groundwater as well as in stream and lake sediments bioaccumulation by plants has been reported in china and korea even endemic diseases have been proposed to be linked with the contamination derived from the weathering and leaching of harmful elements from black shale anthropogenic actions exposing the black shale bedrock and associated soils to oxic conditions further intensifies acid rock drainage regional or nation wide mapping of the black shales is recommended to detect potential risk areas finland has recently completed the country wide mapping program of black shales with airborne geophysics integrated with geological petrophysical and geochemical studies the black shale database is actively used in regional planning and by environmental authorities research institutes and consulting companies in the case of the historical black shale mining areas like in the kupferschiefer in germany restoration measures have been applied to prevent further acid mine drainage in active and future mining projects a comprehensive environmental impact assessment with effective monitoring programmes and closure plans play a crucial role in the prevention of acid mine drainage from the black shale associated deposits

microbial transformations of organic matter in black shales and implications for global biogeochemical cycles abstract the various roles that microorganisms play in transformation of organic matter in geologic environments are yet to be fully revealed many of these roles influence and perhaps control the composition of earth s atmosphere over geologic time by directly impacting global scale cycling of carbon dioxide oxygen and methane one example is the weathering of black shales exposure of organic matter rich sedimentary rocks to oxygenated earth surface conditions results in significant changes in outcrop scale rock geochemistry with implications for element cycling on a global scale this article reviews the progress of ongoing research of a black shale weathering profile exposed near clay city kentucky usa using tools of molecular biology microbial ecology isotope geochemistry and organic geochemistry this research explores the role of microorganisms in utilization and oxidation of sedimentary organic matter and sulfide mineral oxidation and examines the communities of microorganisms that may live in this environment from this and related studies we are developing greater awareness of the importance of microorganisms in transfer of organic materials among various reservoirs of the geosphere biosphere hydrosphere and atmosphere

geology of the devonian black shales of the appalachian basin abstract black shales of devonian age in the appalachian basin are a unique rock sequence the high content of organic matter which imparts the characteristic lithology has for years attracted considerable interest in the shales as a possible source of energy the recent energy shortage prompted the u s department of energy through the eastern gas shales project of the morgantown energy technology center to underwrite a research program to determine the geologic geochemical and structural characteristics of the devonian black shales in order to enhance the recovery of gas from the shales geologic studies by federal and state agencies and academic institutions produced a regional stratigraphic network that correlates the 15 ft black shale sequence in tennessee with 3000 ft of interbedded black and gray shales in central new york these studies correlate the classic devonian black shale sequence in new york with the ohio shale of ohio and kentucky and the chattanooga shale of tennessee and southwestern virginia biostratigraphic and lithostratigraphic markers in conjunction with gamma ray logs facilitated long range correlations within the appalachian basin basinwide correlations including the subsurface rocks provided a basis for determining the areal distribution and thickness of the important black shale units the organic carbon content of the dark shales generally increases from east to west across the basin and is sufficient to qualify as a hydrocarbon source rock significant structural features that involve the black shale and their hydrocarbon potential are the rome trough kentucky river and irvine paint creek fault zone and regional decollements and ramp zones

understanding biomineralization in the fossil record abstract biomineralization the formation of minerals by organisms is a key aspect in the understanding of the fossil record knowing how biominerals form and their properties is important in the correct use of fossils in geochemistry the understanding of evolution and in the interpretation of how geological events have influenced the fossil record throughout the phanerozoic the focus of this contribution rather than a conventional review on the status of this research field is on the importance of highlighting the traditional link between paleontology and biomineralization

quantitative assessment for the rockfall hazard in a post earthquake high rock slope using terrestrial laser scanning abstract geometric information and discontinuity characterization of rock masses are the key aspects of the analysis of the evolution and failure mechanisms of rockfalls with the advantageous use of terrestrial laser scanning tls the accurate three dimensional 3d spatial information of rock slopes can be obtained without contact by conducting a fuzzy k means algorithm in this study the automatic identification of discontinuity sets is achieved and dominant occurrences of rock mass discontinuities in each local region can be acquired in great detail this automatic identification method permits the user to visually identify the discontinuity sets and acquire their spacial distribution features e g occurrences spacings trace lengths and their geometric compounding relationships at the same time based on the shortest distance sd algorithm and the surface to plane volume calculation algorithm the distributions shapes volumes and scars of the rockfalls can be accurately detected over the monitored time interval these methods are able to provide adequate investigations and quantitative assessment for the rockfall failure mechanisms and evolutions of the hongshiyan post failure rock slope after the 2014 ludian earthquake the topography of the landslide surface mechanical properties scales and the structural features of the discontinuities have a significant effect on the failure mechanisms distributions and volumes of rockfalls the main failure mechanisms of the rockfall investigated in this rock slope can be divided into plane failure wedge failure and toppling failure the plane and wedge failures mainly occurred in the landslide surface while the toppling failures are mainly observed along the edge of the post failure slope which is obviously responded by preferred discontinuities the reverse dip stratified structure characteristics and the excavation disturbances during the recovering and slope treatment stage induce numerous progressive and continuous failures of rockfalls the results are beneficial for the design and optimization of rockfall treatments

geochemical evidence for the hydrothermal origin of sulphur base metals and gold in proterozoic metamorphosed black shales kainuu and outokumpu areas finland metamorphosed black shale formations 120 150 m thick with median concentrations of 7 non carbonate carbon and 6 8 sulphur are abundantly met in drill cores in the kainuu and outokumpu areas carbon isotope 3c values are comparable to the average isotopic composition of non carbonate carbon in sedimentary rocks the rare earth element patterns show cerium depletion indicating a marine origin base metal concentrations in black shales are high in the talvivaara mineralization ore estimate 300 mt with 0 26 ni 0 14 cu and 0 53 zn and in the vicinity of ophiolite complexes in the kainuu schist belt the median value for gold is 35 ppb max 170 ppb in the western part and 16 ppb max 180 ppb in the east highest platinum and palladium concentrations encountered are 60 70 ppb it is shown that in the kainuu black shales concentrations of sulphur base metals and precious metals have been increased by hydrothermal processes as indicated by positive europium anomalies elevated mercury concentrations max 7 5 ppm high sulphur isotope 34s values and the enrichment of sulphur and base metals relative to carbon the processes operative during the deposition of these shales find an analogy in recent processes in ocean ridge spreading axes

uraniferous bitumen nodules in the talvivaara ni zn cu co deposit finland influence of metamorphism on uranium mineralization in black shales in the central part of the fennoscandian shield the talvivaara ni zn cu co deposit hosted by palaeoproterozoic metamorphosed black schists contains low uranium concentrations ranging from 10 to 30 ppm the talvivaara black schists were deposited 2 0 1 9 ga ago and underwent subsequent metamorphism during the 1 9 1 79 ga svecofennian orogeny anhedral uraninite crystals rimmed by bitumen constitute the main host of uranium u pb secondary ion mass spectrometry dating indicates that uraninite crystals were formed between 1 878 17 and 1 871 43 ma during peak metamorphism rare earth element patterns and high th content average 6 38 wt in disseminated uraninite crystals indicate that u was concentrated during high temperature metamorphism 400 c the formation of bitumen rims around uraninite may be explained by two distinct scenarios a a transport of u coincident with the migration of hydrocarbons or b post metamorphic formation of bitumen rims through radiolytic polymerization of gaseous hydrocarbons at the contact with uraninite

submarine hydrothermal contribution for the extreme element accumulation during the early cambrian south china throughout the geological history of the earth submarine hydrothermal activity has played an important role in seawater chemistry biological evolution and enrichment of metals in the earth crust however the prospect of hydrothermal activity for extreme element accumulation during the early cambrian a key geological period in south china has not been well constrained this study reports geochemical e g ree and sr isotope investigations of a coarse grained limestone layer and associated calcite veins in zunyi and nayong areas guizhou province to constrain the hydrothermal activity and evaluate the significance of hydrothermal contribution to extreme element accumulation during the early cambrian south china our results reveal positive eu anomalies and higher initial 87sr 86sr ratios 0 7083 0 7150 for carbonate samples than those of early cambrian seawater indicating the presence of hydrothermal processes combined with constraints from the spatial relationships and coincidence with adjacent mineralization these hydrothermal processes provide the most probable contribution for polymetallic ni mo pge mineralization furthermore there are abundant hydrothermal dolomite and barite calcite veins in the dolostone of the dengying formation indicating the occurrence of a variety of hydrothermal fluids overall multi stage hydrothermal pulses with different fluid compositions spanned the ediacaran cambrian transition in south china in particular these hydrothermal fluids with positive eu anomalies and enriched radiogenic sr originating from proterozoic mafic ultramafic rocks may have flowed through the underlying precambrian silicate clastic rocks e g xiajiang banxi and lengjiaxi groups and may have been crucial for the marine environment biological diversity and extreme element accumulation during the early cambrian south china

detection and spatial prediction of rockfalls by means of terrestrial laser scanner monitoring abstract a rock face affected by small rockfalls has been monitored using a ground based remote sensing apparatus terrestrial laser scanner tls the pilot study area corresponds to the main scarp of the 1881 puigcercos landslide pallars jussa catalonia spain four datasets of the slope were acquired from september 2007 to july 2008 in an ongoing project the geomorphological evolution of the rock face in terms of volume and frequency of rockfall was studied by the comparison of sequential datasets in addition to the detection of past events this study deals with the spatial prediction of rockfalls through the detection of pre failure deformation as a precursory indicator the high resolution and accuracy and the maximum range of the tls offer interesting prospects for both spatial location and prediction of rockfall

reactions of hydrothermal solutions with organic matter in paleoproterozoic black shales at talvivaara finland evidence from multiple sulfur isotopes abstract stable isotopic studies of archean paleoproterozoic sedimentary rocks older than 2 4 ga have documented large mass anomalous fractionations of sulfur isotopes 33 s 0 0 2 while younger rocks record little to no anomalous fractionation of sulfur isotopes this change from large anomalous fractionations to sulfur isotope values that fall on the terrestrial fractionation line has been proposed to represent the transition from an essentially anoxic archean atmosphere to an oxygenated atmosphere here we present 34 s and 33 s data for 28 core samples from paleoproterozoic 2 1 1 9 ga metamorphosed black shales and associated sulfide ores in eastern finland previous 34 s of studies of the talvivaara and outokumpu deposits of eastern finland focused on single grain analyses of sulfides while this study presents data from sequentially extracted sulfur fractions e g acid soluble sulfides chrome reducible sulfides elemental sulfur the sulfur isotope results range between 16 6 and 11 6 for 34 s 8 6 and 6 0 for 33 s and 1 25 and 0 55 for 33 s the anomalously fractionated samples are not consistent with previous findings that large anomalous fractionations of sulfur isotopes are absent in sedimentary metasedimentary rocks younger than 2 4 ga it is unlikely that talvivaara sulfides are the products of ultraviolet photolysis of volcanic so 2 in an oxygen poor atmosphere alternatively these sulfides could in part be the products of diagenetic reactions between sediments enriched in organic matter c org and hydrothermal solutions rich in sulfate i e thermochemical sulfate reduction laboratory experiments on thermochemical sulfate reduction have shown that mass anomalous fractionations of sulfur isotopes can be recorded in reduced sulfur products from reactions between simple amino acids and sulfate at 150 300 c a thermochemical sulfate reduction pathway for the mass anomalous signatures in talvivaara samples is consistent with previous genetic models proposed for the origin of the sulfur and organic carbon rich black shales now schists associated with the talvivaara and outokumpu ore deposits at talvivaara metalliferous black shales apparently were deposited under an anoxic to sulfidic marine water column the reported multiple sulfur isotopic data are key geological evidence for mass anomalous fractionations of sulfur isotopes during hydrothermal alteration of fine grained organic rich sediments approximately 20 of samples in this study show large offsets in 33 s values between different extracted sulfur fractions from the same sample which can be explained by classical isotope effects associated with the formation of hydrothermal alteration products that predominantly are retained within the precursor fine grained organic rich units

the application of a long range laser scanner for monitoring volcanic activity on mount etna abstract there is a requirement for rapid remote monitoring of ground deformation of volcanoes especially during eruptions a long range reflector less laser scanning instrument manufactured by riegl laser measurement systems was used on mount etna in october 2000 and its potential for monitoring ground surface changes associated with volcanic activity was evaluated the 3dlm lr1 scanner system can measure distances up to 2 km with an accuracy of 25 mm in typical conditions measurement rates range from 1 point per second at 2 km to 4 points per second at 10 m the system also records reflective intensity and this proved useful in distinguishing between different types of volcanic material cloud and gas obscured some measurements but the scanning nature of the instrument coupled with effective data filtering software allowed robust digital terrain models to be created

organic geochemistry and mineralogy i characterisation of organic matter associated with metal deposits abstract as geochemical appraisals of mineral regions of commercial prospectivity evolve the organic matter associated with metal rich ores has attracted greater attention petroleum basin and modern seafloor hydrothermal vent studies have suggested that organic matter can have a significant influence on the behaviour of mineralising fluids there have been many isolated reports of certain organic compositional or morphological e g pyrobitumen features showing an apparent relationships with hydrothermal fluids or minerals raising expectations that organic based parameters might be useful to mineral exploration however the understanding of organic inorganic relationships in earth systems is far from complete for example the detailed mechanics of the interaction of organics with hydrothermal fluids over geological time remain largely undefined organic geochemistry studies have traditionally involved the measurement and interpretation of the hydrocarbon composition of sedimentary rocks here we review the types of aliphatic hydrocarbons aromatic hydrocarbons and metalloporphyrins often detected from organic geochemical investigations in mineral rich regions such molecular data can be particularly diagnostic of biochemical sources and the palaeo environments at the time mineral associated organic matter was deposited sub surface trends of hydrocarbon alteration may also reflect major biogeochemical processes such as thermal maturity and biodegradation organic geochemistry data can also occasionally provide information about the nature e g origin composition temperatures and migration pathways of hydrothermal fluids and can make a contribution to holistic ore genesis models the well preserved organic matter associated with the economic here s your chance pb zn ag mine paleoproterozoic barney creek formation mcarthur basin australia and the transition metal rich early permian kupferschiefer formation germany poland have attracted significant attention a more detailed summary of the organic character of these deposits is provided to highlight the contribution organic geochemistry can make to understanding mineralisation processes most organic geochemical studies of highly mineralised regions however have not adequately addressed the significance of organic matter to mineralisation a slightly different analytical focus than traditionally used for exploration appraisal of petroleum hydrocarbons may be required to properly evaluate the significance of organic species to the mobilisation transport and deposition of ore metals the characterisation and subsequent thermodynamic modeling of organic substances and complexes within metalliferous hydrothermal systems will contribute to a better understanding of the nature and role of organic inorganic fluids or other affiliated organics in ore systems

a c mos2 mixed layer phase mosc occurring in metalliferous black shales from southern china and new data on jordisite a new phase composed mainly of mo s and c and referred to herein as mosc occurs widely in organic rich metalliferous cambrian black shales in south china mosc which has previously been referred to as jordisite has been studied by scanning electron microscopy sem electron microprobe analysis empa transmission electron microscopy tem powder x ray diffraction xrd extended x ray absorption fine structure exafs and catalytic activity tem data show mosc to have a layered structure with packets resembling molybdenite and graphite like carbon that average five layers in thickness analytical data are consistent with an idealized formula of mo3s6c10 but it commonly contains 1 3 wt each of fe ni and as so that its composition may be better approximated by the formula mo fe ni 3 s as 6c10 selected area electron diffraction saed patterns show a small number of broad inhomogeneous rings corresponding to randomly oriented layers arranged in subspherical cells a single broad weak peak corresponds to a 10 11 a layer spacing in powder xrd diffraction patterns pseudomorphism after fossil bacteria implies an origin by replacement of sedimentary organic material in its chemical properties and structure mosc resembles synthetic compounds used as catalysts for hydrodesulfurization hds in the petrochemical industry the large surface to volume ratio for mosc may be an important factor in its relatively strong hds catalytic activity cotype samples of jordisite from germany previously thought to be amorphous mos2 were also studied by sem and tem jordisite occurs as sequences of a few curved layers that form sub spherical units with an appearance remarkably like that of mosc however the layer spacing is 6 a like that of molybdenite the ratio of mo s is 1 2 and no carbon was detected although it coexists with kerogen jordisite is thus confirmed to be a form of mos2 but because powder diffraction like saed patterns were obtained it is not amorphous

the relative mobility of trace elements from short term weathering of a black shale abstract black shales contain high concentrations of trace elements which may be liberated to the environment as a result of natural weathering and potentially during shale gas development and future mining of black shales for extraction of shale oil the sunbury shale is one of the youngest units making up the thick devonian and mississippian black shale sequence in the appalachian basin this study compares the trace element geochemistry of samples collected from two exposures of sunbury shale located

hydrothermal biogenic and seawater components in metalliferous black shales of the brooks range alaska synsedimentary metal enrichment in a carbonate ramp setting trace element and os isotope data for lisburne group metalliferous black shales of middle mississippian early chesterian age in the brooks range of northern alaska suggest that metals were sourced chiefly from local seawater including biogenic detritus but also from externally derived hydrothermal fluids these black shales are interbedded with phosphorites and limestones in sequences 3 to 35 m thick deposition occurred mainly on a carbonate ramp during intermittent upwelling under varying redox conditions from suboxic to anoxic to sulfidic deposition of the black shales at 335 ma was broadly contemporaneous with sulfide mineralization in the red dog and drenchwater zn pb ag deposits which formed in a distal marginal basin relative to the composition of average black shale the metalliferous black shales n 29 display large average enrichment factors 10 for zn 10 1 cd 11 0 and ag 20 1 small enrichments 2 10 are shown by v cr ni cu mo pd pt u se y and all rare earth elements except ce nd and sm a detailed stratigraphic profile over 23 m in the skimo creek area central brooks range indicates that samples from at and near the top of the section which accumulated during a period of major upwelling and is broadly correlative with the stratigraphic levels of the red dog and drenchwater zn pb ag deposits have the highest zn toc total organic carbon cu toc and tl toc ratios for calculated marine fractions no detrital component of these three metals average authigenic detrital free contents of mo v u ni cu cd pb ge re se as sb tl pd and au show enrichment factors of 4 3 103 to 1 2 106 relative to modern seawater such moderate enrichments which are common in other metalliferous black shales suggest wholly marine sources seawater and biogenic material for these metals given similar trends for enrichment factors in organic rich sediments of modern upwelling zones on the namibian peruvian and chilean shelves the largest enrichment factors for zn and ag are much higher 1 4 107 and 2 9 107 respectively consistent with an appreciable hydrothermal component other metals such as cu pb and tl that are concentrated in several black shale samples and are locally abundant in the red dog and drenchwater zn pb ag deposits may have a partly hydrothermal origin but this cannot be fully established with the available data enrichments in cr up to 7 8 106 are attributed to marine and not hydrothermal processes the presence in some samples of large enrichments in eu up to 6 1 107 relative to modern seawater and of small positive eu anomalies eu eu up to 1 12 are considered unrelated to hydrothermal activity instead being linked to early diagenetic processes within sulfidic pore fluids initial os isotope ratios 187os 188os calculated for a paleontologically based depositional age of 335 ma reveal moderately unradiogenic values of 0 24 to 0 88 for four samples of metalliferous black shale a proxy for the ratio of coeval early chesterian seawater is provided by initial 187os 188os 335 ma ratios of four unaltered black shales of the coeval kuna formation that average 1 08 nearly identical to the initial ratio of 1 06 for modern seawater evaluation of possible sources of unradiogenic os in the metalliferous black shales suggests that the most likely source was mafic igneous rocks that were leached by externally derived hydrothermal fluids this unradiogenic os is interpreted to have been leached by deeply circulating hydrothermal fluids in the kuna basin followed by venting of the fluids into overlying seawater we propose that metal bearing hydrothermal fluids that formed zn pb ag deposits such as red dog or drenchwater vented into seawater in a marginal basin were carried by upwelling currents onto the margins of a shallow water carbonate platform and were then deposited in organic rich muds together with seawater and biogenically derived components by syngenetic sedimentary processes metal concentration in the black shales was promoted by high biologic productivity sorption onto organic matter diffusion across redox boundaries a low sedimentation rate and availability of h2s in bottom waters and pore fluids

structural and geomorphological features of landslides in the bhutan himalaya derived from terrestrial laser scanning abstract this study presents data on landslides affecting the main west east transport corridor in the himalaya of eastern bhutan close to the main central thrust the study focuses on the extraction of structural and geometrical information from terrestrial laser scanning tls data utilising a case study landslide the namling landslide analyses of the tls data allow extraction of slide geometry discontinuity orientations and identification of the mode of failure the tls results are compared to a traditional engineering geological survey and prove to yield considerable added value and should form the basis of new approaches to geomorphological studies and site assessment macro scale geomorphological reconnaissance findings are outlined and interpreted within a conceptual model of the evolution of landslide features here termed hierarchical landsliding it is concluded that the nam ling landslide is indicative of deeper seated deformation and is not purely a function of road construction

chemical and mineralogical analysis of devonian black shale samples from martin county kentucky carroll and washington counties ohio wise county virginia and overton county tennessee u s a abstract core samples of devonian shales from five localities in the appalachian basin have been analyzed chemically and mineralogically the amounts of major elements are similar however the minor constituents organic c s phosphate and carbonate show ten fold variations in amounts trace elements mo ni cu v co u zn hg as and mn show variations in amounts that can be related to the minor constituents all samples contain major amounts of quartz illite two types of mixed layer clays and chlorite in differing quantities pyrite calcite feldspar and kaolinite are also present in many samples in minor amounts dolomite apatite gypsum barite biotite and marcasite are present in a few samples in trace amounts trace elements listed above are strongly controlled by organic c with the exception of mn which is associated with carbonate minerals amounts of organic c generally range from 3 to 6 and s is in the range of 2 5 amounts of trace elements show the following general ranges in ppm parts per million co 20 40 cu 40 70 u 10 40 as 20 40 v 150 300 ni 80 150 high values are as much as twice these values the organic c was probably the concentrating agent and the organic c and sulfide s together created an environment that immobilized and preserved these trace elements closely spaced samples showing an abrupt transition in color also show changes in organic c s and trace element contents several associations exist between mineral and chemical content pyrite and marcasite are the only minerals found to contain sulfide s in general the illite chlorite mixed layer clay mineral shows covariation with organic c if calcite is not present the enriched trace elements are not related to the clay types although the clay and organic matter are intimately associated as the bulk fabric of the rock

semi automatic extraction of rock mass structural data from high resolution lidar point clouds abstract in this paper a matlab tool called diana discontinuity analysis for the 2d and 3d geo structural analysis of rock mass discontinuities on high resolution laser scanning data is presented the proposed approach is able to semi automatically retrieve some relevant rock mass parameters namely orientation number of sets spacing frequency and derived rqd persistence block size and scale dependent roughness by analyzing high resolution point clouds acquired from terrestrial or aerial laser scanners in addition with a specific diana option called filterveg we are able to remove vegetation or other disturbing objects from the point cloud which is one of the main problems in lidar data processing some examples of the proposed method have demonstrated its ability to investigate rock masses characterized by irregular block shapes and suggest applications in the field of engineering geology and emergency management when it is often advisable to minimize survey time in dangerous environments and in the same time it is necessary to gather all the required information as fast as possible

georadiochemical evidence to weathering of mining residues of the mansfeld mining district germany mining heaps are used as archives for the investigation of weathering processes aim of this work was to investigate the different weathering behavior of heap materials derived from kupferschiefer mining with respect to environmental hazard for this purpose kupferschiefer and slag material of two heaps of different age were examined regarding to the radionuclide distribution and geochemical composition by measuring of the local dose rate performing digital autoradiography and gamma spectrometry the radiological load of the heaps and the heap materials was determined the geochemical characterization of the samples was performed by xrf icp oes and icp ms the results show a clear higher radionuclide load of the younger slag heap a depletion of chalcophile and lithophile elements in the older slag was determined apart from a homogeneous radionuclide distribution considerable radionuclide enrichments in fossil fragments could be proven the results reveal a different weathering behavior of slag material in comparison to the kupferschiefer depending on the chemical binding of the elements on organic and inorganic species natural organic matter as well as apatite in kupferschiefer act as retention barrier for some metals

a review of the origins of metal rich pennsylvanian black shales central u s a with an inferred role for basinal brines abstract compared to most shales even most black shales numerous thin pennsylvanian marine black shales of the u s midwest are very enriched in organic c 5 40wt and heavy elements for example instrumental neutron activation analysis of 74 samples of mostly black and dark gray pennsylvanian shales of the u s midwest average 1300 ppm zn 85 ppm u 655 ppm mo 130 ppm se and 55 ppm cd amounts sufficient to raise concerns about heavy element pollution direct precipitation of sulfides and fixation by abundant organic matter during sedimentation and early diagenesis may account for heavy metals contained by shales in most cases metal supply calculations however indicate that a special source would be needed to supply metals for a strictly syngenetic origin possible sources for such metals include submarine hot springs and pennsylvanian seas that may have been more enriched in metals than modern ocean water at least at some localities additional metal values may have been added later from basinal brines e g zn or from modern groundwaters e g mo se u the actions of modern supergene processes may fix metals mitigating detrimental effects from black shales

characterization of sulfide deposits by airborne magnetic and gamma ray responses in eastern finland abstract integrated interpretation of aerogeophysical data permits geophysical characterization of sulfide deposits in eastern finland the structural control and the hydrothermal alteration of the rocks can be discerned from airborne magnetic and radiometric data the cu co zn deposits associated with serpentinite dolomite calc silicate rock siliceous rock black shale settings of the outokumpu type are locally characterized by reduced intensity of magnetization and electrical conductivity and reduced eth and k radiation enhanced eu eth anomalies are commonly spatially related to major structural lineaments such as the boundaries of structurally more coherent bedrock blocks or intersections of faults and shear zones electromagnetic surveys can be used to distinguish black shales and serpentinites in the region the sulfide deposits in eastern finland can be divided into two groups on the basis of airborne geophysical characteristics 1 intense magnetization and high electrical conductivity and 2 moderate magnetization and electrical conductivity in the sulfide deposits of group 1 ore forming constituents mainly precipitated during primary sedimentation for example the black shale hosted ni cu zn ore at talvivaara group 2 is related to sulfide deposits where major ore forming processes have affected the associated black shale formation after the sedimentation phase outokumpu type cu co zn deposits in cases where the magnetization and electrical conductivity of black shales are especially weak ore formation processes probably continued during late metamorphic or post metamorphic deformation the theoretical basis for the observed differences in magnetic response between different deposits has to do with the mineralogy of the black shales pyrite changes into ferrimagnetic monoclinic pyrrhotite during metamorphism above greenschist facies especially along tectonic structures if no further alteration occurs pyrrhotite bearing black shale formations appear as highly magnetic and electrically conductive zones on geophysical maps wherever intense tectonic deformation emplacement of quartz sulfide veins hydrothermal alteration or contact metamorphism has affected the black shale formation after sedimentation both magnetic and electromagnetic responses may be weakened because of diminished amounts of the pyrrhotite bearing and graphite rich material in addition the presence of antiferromagnetic pyrrhotite of hexagonal crystal structure may decrease the magnetic response the classification presented here applies specifically to eastern finland but may be widely applicable to terranes with abundant black shale formations that have undergone regional metamorphism of upper greenschist facies or higher association of sulfide ores with black shales is a common feature in the geological record our integrated geophysical method offers a quick way of examining large areas and it should prove useful in the search for sulfide deposits in other parts of the world

metal dispersion in groundwater in an area with natural and processed black shale nationwide perspective and comparison with acid sulfate soils black shale is often rich in sulfides and trace elements and is thus a potential environmental threat in a manner similar to acid sulfate soils and active or abandoned sulfide mines this study aims at characterising how exposed and processed mined and burnt black shale alum shale in degerhamn se sweden affects the chemistry al as ba cd ca cr co cu fe pb mg mn mo ni k si na sr s u v and zn of the groundwater there were large variations in groundwater chemistry between nearby sampling points while the temporal variations generally were small acidic groundwater around ph 4 found in deposits of burnt and carbonate poor shale where the conditions for sulfide oxidation were favourable was strongly elevated in al u and several chalcophilic metals cd co cu ni and zn cadmium and u were also together with mo abundant in many of the near neutral waters both in the non mined black shale bedrock and in the deposits of burnt shale an extrapolation to a national level suggests that the dispersion of ni from naturally occurring black shale is similar to that from anthropogenic point sources while for cd and as it is assessed to be approximately one tenth of that from point sources the processed shale was however a much larger source of metals than the black shale bedrock itself showing this material s potential as a massive supplier of metals to the aquatic environment a comparison of waters in contact with the processed cambrian ordovician black shale in degerhamn and acid sulfate soils of the region shows that these two sulfide bearing materials in many respects very different delivers basically the same suite of trace elements to the aquatic environment this has implications for environmental planning and protection in areas where these types of materials exist

ni cu pge deposits in finland geology and exploration potential abstract several types of nickel sulphide deposits occur in finland some of them are also important sources of cu co and pge the main deposit types are related to archaean and palaeoproterozoic mafic to ultramafic rocks palaeoproterozoic metamorphosed black shales of the talvivaara type or the ultramafic and metasomatic calc silicate rocks of the ophiolitic outokumpu association several komatiite hosted ni cu pge deposits have been discovered in the archaean and paleoproterozoic greenstone belts in northern and eastern finland but only one has been briefly mined in 1989 many 2 44 ga palaeoproterozoic mafic ultramafic layered intrusions in finland host contact type pge ni cu deposits and significant reef type pge deposits typically the ni resources are of low grade but large tonnage the mafic ultramafic magmatism at ca 2 06 ga produced significant ni cu pge resources in the central lapland greenstone belt including the kevitsa and sakatti deposits the svecofennian domain in central and southern finland contains hundreds of small ca 1 88 ga mafic ultramafic orogenic intrusions many of these host nickel mineralization nickel exploration potential was evaluated in general based on identification of critical factors within a mineral system framework and a quantitative assessment of the potential occurrence of undiscovered nickel resources the mgo content of the parental magma was estimated for 28 deposits 6 komatiite hosted occurrences and 22 svecofennian orogenic intrusions the estimated mgo content of the parental magmas for the selected deposits varies from around 7 to 15 in basaltic to komatiitic basalt systems and up to 30 in more magnesian komatiitic systems the ni cu value varies mostly between 0 7 and 12 correlating in general positively with the mgo content of the magma exceptionally high or low ni cu values in some deposits may result from for example copper loss during post magmatic processes serpentinization and or metamorphism or part of the sulphide ore zoned by the ni cu value still being unknown recent advances in understanding of komatiites in finland indicates high exploration potential for nickel within the paleoproterozoic komatiitic formations which typically are also significantly enriched in cu and pge however the quantitative assessment of undiscovered nickel resources in finland suggests that the contact type ni cu pge deposits hosted by 2 44 ga mafic ultramafic layered intrusions in northern finland have the greatest potential for hosting undiscovered resources among the assessed nickel deposit types these occur within restricted areas resulting in a high deposit density finally considerable nickel resources might exist in undiscovered talvivaara kevitsa or sakatti type deposits these deposit types should be assessed as soon as more geological information becomes available