antimony and arsenic anomalies in the coal seams from the gokler coalfield gediz turkey abstract the gokler coalfield in the western part of turkey mainly contains high sulphur 4 5 to 11 5 on a dry basis bituminous 0 5 to 0 95 rr coals of middle miocene age the gokler coals from buyuk kucuk and unnamed seams are in general characterised on a mineral matter free basis by higher amounts of macerals of the vitrinite group av 95 5 than liptinite av 2 5 and inertinite av 2 contents geochemical characterisation of 45 coal samples on a whole coal dry basis was achieved using an energy dispersive polarised x ray fluorescence edp xrf spectrometer the gokler coals proved to be anomalously enriched in sb 8 3 2347 ppm av 134 ppm and as 170 3854 ppm av 833 ppm in the samples in comparison with range values for most world coals sb and as are respectively associated with epigenetic stibnite and iron sulfides both of which formed in microfractures and micropores in the gokler coals stibnite occurs mainly as prismatic crystals and less radial crystals scanning electron microscopy sem shows that some stibnites are chemically pure while others contain minor fe epigenetic fe sulfides pyrite and marcasite typically include in addition to fe and s minor amounts of as and trace amounts of zn as and zn are below the sem detection levels in syngenetic framboidal pyrites epigenetic calcites in the samples consist mainly of mg and fe and trace amounts of sr all epigenetic minerals such as stibnite iron sulfides calcite and quartz indicated that the gokler coals were mainly effected by post miocene hydrothermal mineralisations

geodetic imaging of thermal deformation in geothermal reservoirs production depletion and fault reactivation abstract we investigate thermally induced surface deformation in geothermal systems to define source mechanisms at depth we assess the mechanical process of subsurface deformation by assuming a spherically cooled fractured reservoir in an infinite medium and derive relations that define magnitudes of thermal contraction stress change and permeability evolution the magnitude of thermal deformation in typical geothermal system is larger than anticipated and suggests two different modalities of surface subsidence thermal contraction and fault reactivation here surface deformation vertical displacement surface tilt and horizontal strain induced by the two different modalities are assessed with mogi contraction and okada slip models and compared with instrumental sensitivity of high precision surface geodetic tools we show that 1 year of geothermal operation at 10 mw with a power plant conversion efficiency of 12 can yield 3 0 104 m3 of subsurface volume change for a reservoir at 2000 m depth this induces 1 7 mm of vertical surface displacement 800 nano radians of surface tilt and 900 nano strains of surface strain this result implies that typically observed magnitudes of surface subsidence order of cm year are naturally expected in massive 100 mw scale geothermal operations and observed surface subsidence may largely be the result of thermal contraction conversely thermal unloading can trigger fault reactivation analysis with an okada slip model shows these shear offsets on pre existing faults can also result in surface deformations of considerable magnitude our analysis of field operational data from various geothermal projects suggests that both thermal contraction and slow fault reactivation may contribute to the observed large surface deformation comparison of predicted deformation with instrumental sensitivity of high precision surface tools confirms that geodetic signals especially tilt and strain are indeed sufficiently large to describe reservoir evolution and to potentially deconvolve reservoir parameters of interest such as permeability

geodetic imaging reservoir monitoring using satellite interferometry summary fluid fluxes within subsurface reservoirs give rise to surface displacements particularly over periods of a year or more observations of such deformation provide a powerful tool for mapping fluid migration within the earth providing new insights into reservoir dynamics in this paper we use interferometric synthetic aperture radar insar range changes to infer subsurface fluid volume strain at the coso geothermal field furthermore we conduct a complete model assessment using an iterative approach to compute model parameter resolution and covariance matrices the method is a generalization of a lanczos based technique which allows us to include fairly general regularization such as roughness penalties we find that we can resolve quite detailed lateral variations in volume strain both within the reservoir depth range 0 4 2 5 km and below the geothermal production zone 2 5 5 0 km the fractional volume change in all three layers of the model exceeds the estimated model parameter uncertainty by a factor of two or more in the reservoir depth interval 0 4 2 5 km the predominant volume change is associated with northerly and westerly oriented faults and their intersections however below the geothermal production zone proper the depth range 2 5 5 0 km there is the suggestion that both north and northeast trending faults may act as conduits for fluid flow

latitudinal and seasonal variations of inertial gravity wave activity in the lower atmosphere over central china 1 gravity wave activities and background dynamical structure in the troposphere and lower stratosphere tls over five stations at latitudes from 10 n to 40 n were statistically studied by using the data from radiosonde observation on a twice daily basis at 0800 and 2000 lt the background dynamical structure exhibits evident latitudinal and seasonal variations and has a profound influence on inertial gravity waves in the tls in the analyses of inertial gravity waves according to the background structures the observation height coverage is divided into two segments which are the tropospheric 0 10 km and lower stratospheric segments 18 25 km the observational results indicate that the tropospheric jet is the most important excitation source for gravity waves both in the troposphere and lower stratosphere and it plays different roles in determining the morphology of gravity waves in these two segments the jet excited gravity waves in the troposphere can propagate both upward and downward and only part of the upward propagating waves can penetrate into the stratosphere because of the doppler shifting by the jet while in the lower stratosphere gravity waves excited by the tropospheric jet propagate upward most differences between the tropospheric and lower stratospheric results can be explained from the linear dispersion relations of gravity waves and the doppler shifting by the strong tropospheric jet however such an explanation is qualitative rather than quantitative generally the observations reveal that the tropospheric gravity waves are mainly controlled by their excitation sources implying the wave characteristics may be regarded as at least an indicator of the wave excitation source characteristics these results suggest that in order to attain a more realistic source parameterization for gravity waves propagating in the middle and upper atmosphere more attention should be paid to the gravity waves in the troposphere moreover the causes of the pronounced peak of lower stratospheric gravity wave intensity at tropical latitudes revealed by previous observations are also discussed

modelling the hydrogeochemical evolution of mine water in a decommissioned opencast coal mine abstract a method for the geochemical modelling of transient contaminant release from rehabilitated opencast coal mines including calibration against existing data is proposed the need for such a methodology is illustrated by a directive received by a decommissioned opencast coal mine in mpumalanga south africa groundwater monitoring data geochemical analyses numerical flow modelling and geochemical modelling are used to model the hydrogeochemical evolution of mine water over time models presented in this study are based on a conceptual model detailing groundwater levels and flow directions hydraulic conductivities groundwater chemistry precipitation evaporation surface water bodies and potential sources additional to this mineralogical analyses leaching tests and acid base accounting were performed to obtain a better understanding of the site geochemistry a geochemical model was constructed which was used to obtain a statistically representative mineral assemblage based on laboratory data which was calibrated against leaching test data this assemblage was simulated in field conditions as input to a numerical flow and transport model the transport of sulfate was modelled accordingly and sulfate concentrations from monitoring data were used for chemical calibration following this long term contaminant release was simulated calibration graphs from the transport model indicated concentrations within a 20 mg l error margin showing that the proposed methodology can be used to calculate contaminant concentrations in an aquifer over time within an acceptable range this approach could provide an improved estimate of the duration of the first flush which upon completion will transform decommissioned collieries into large scale reservoirs of utilisable groundwater

seismicity triggered by fluid injection induced aseismic slip anthropogenic fluid injections are known to induce earthquakes the mechanisms involved are poorly understood and our ability to assess the seismic hazard associated with geothermal energy or unconventional hydrocarbon production remains limited we directly measure fault slip and seismicity induced by fluid injection into a natural fault we observe highly dilatant and slow 4 micrometers per second m s aseismic slip associated with a 20 fold increase of permeability which transitions to faster slip 10 m s associated with reduced dilatancy and micro earthquakes most aseismic slip occurs within the fluid pressurized zone and obeys a rate strengthening friction law 0 67 0 045ln v v with v 0 1 m s fluid injection primarily triggers aseismic slip in this experiment with micro earthquakes being an indirect effect mediated by aseismic creep

petrographic and reflectance analysis of solvent swelled and solvent extracted south african vitrinite rich and inertinite rich coals maceral transitions during solvent swelling and extraction of two south african coals similar in rank and age but different in maceral composition were evaluated inertinite rich highveld coal dominated by semifusinite and vitrinite rich waterberg coal were used maceral group analysis of solvent extracted and solvent swelled residues showed no changes in the maceral composition for both coals solvent extracted residues exhibited significant observable changes of some particles particle fracturing decrease in reflectance and rounding of particle edges inertinite rich coal exhibited extensive fracturing during solvent treatment random reflectance analyses of both coals showed that solvent treatment reduces reflectance values of both vitrinite and inertinite vitrinite reflectograms showed a shift from the dominant reflecting v types to lower reflecting v types the inertinite reflectograms exhibited an increase in the number of reflecting inertinite types i types with solvent treatment resulting in a broadening of the reflectograms the changes in reflectance between the original and solvent treated coal may be attributed to a combination of structural elemental or surface changes current data for these south african coals suggests a relationship between solvent extraction and mean random reflectance the higher the extraction yields the lower the mean random reflectance

average qlg qsn and observation of lg blockage in the continental margin of nova scotia the term lg blockage refers to the sudden disappearance of the lg phase along a particular propagation path which is commonly seen at continental oceanic transition zones in this paper we present observational evidence of lg blockage across the continental margin of nova scotia in eastern canada regional lg and sn spectra from 91 events with epicentral distances between 100 and 1200 km and magnitudes between 2 5 and 4 7 are inverted simultaneously for the source spectrum site amplification and average attenuation the vertical displacement spectra were estimated between 0 9 and 10 75 hz the assumptions include a fixed frequency independent geometric spreading rate for lg and a frequency dependent spreading model for the sn estimates for the apparent regional attenuations are qlg f 615 25 f0 35 0 04 and qsn f 404 23 f0 45 0 03 results from this study provide an accurate parameterization of observed amplitude spectra and are valuable for representing wave propagation in the region based on the observation of a strong trade off between sn and lg amplitudes which have different attenuation characteristics we conclude any attenuation study based on measuring amplitude of a package of several different phases without taking into consideration the propagation characteristics of individual waveforms at the region of study may bias the estimation of average regional q

origin and significance of high nickel and chromium concentrations in pliocene lignite of the kosovo basin serbia abstract trace element data from 59 pliocene lignite cores from the lignite field in the kosovo basin southern serbia show localized enrichment of ni and cr 33 304 ppm and 8 176 ppm respectively whole coal basis concentrations of both elements decrease from the western and southern boundaries of the lignite field low temperature ash and polished coal pellets of selected bench and whole coal samples were analyzed by x ray diffraction and scanning electron microscopy with energy dispersive x ray analyses these analyses show that most of the ni and cr are incorporated in detrital and to a lesser degree in authigenic minerals the ni and cr bearing detrital minerals include oxides chromites serpentine group minerals and rare mixed layer clays possible authigenic minerals include ni fe sulfates and sulfides analyses of three lignite samples by a supercritical fluid extraction technique indicate that some 1 11 of the ni is organically bound ni and cr bearing oxides mixed layer clays chromites and serpentine group minerals were also identified in weathered and fresh samples of laterite developed on serpentinized paleozoic peridotite at the nearby glavica and cikatovo ni mines these mines are located along the western and northwestern rim respectively of the kosovo basin where ni contents are highest the detrital ni and cr bearing minerals identified in lignite samples from the western part of the kosovo basin may have been transported into the paleoswamp by rivers that drained the two paleocene laterites some ni may have been transported directly into the paleoswamp in solution or alternatively ni may have been leached from detrital minerals by acidic peat water and adsorbed onto organic matter and included into authigenic mineral phases no minable source of ni and cr is known in the southern part of the lignite field however the mineral and chemical data from the lignite and associated rocks suggest that such a source area may exist

understanding the hydromechanical behavior of a fault zone from transient surface tilt and fluid pressure observations at hourly time scales flow through reservoirs such as fractured media is powered by head gradients which also generate measurable poroelastic deformation of the rock body the combined analysis of surface deformation and subsurface pressure provides valuable insights of a reservoir s structure and hydromechan ical properties which are of interest for deep seated co 2 or nuclear waste storage for instance among all surveying tools surface tiltmeters offer the possibility to grasp hydraulically induced deformations over a broad range of time scales with a remarkable precision here we investigate the information content of transient surface tilt generated by the pressurization a kilometer scale subvertical fault zone our approach involves the combination of field data and results of a fully coupled poromechanical model the signature of pressure changes in the fault zone due to pumping cycles is clearly recognizable in field tilt data and we aim to explain the peculiar features that appear in 1 tilt time series alone from a set of four instruments and 2 the ratio of tilt over pressure we evidence that the shape of tilt measurements on both sides of a fault zone is sensitive to its diffusivity and its elastic modulus the ratio of tilt over pressure predominantly encompasses information about the system s dynamic behavior and extent of the fault zone and allows separating contributions of flow in the different compartments hence tiltmeters are well suited to characterize hydromechanical processes associated with fault zone hydrogeology at short time scales where spaceborne surveying methods fail to recognize any deformation signal

the record of triassic charcoal and other evidence for palaeo wildfires signal for atmospheric oxygen levels taphonomic biases or lack of fuel abstract as wildfires are today important sources of disturbance in many terrestrial ecosystems it is of great interest to understand how different environmental parameters and fire activity interacted during past periods of the earth history fossil charcoal inertinites and pyrogenic polycyclic aromatic hydrocarbons pahs represent the only direct evidence for the occurrence of such palaeo wildfires in the present study a review of published data together with new data on the occurrence of fossil charcoal for the permian and the triassic is presented for a long time it has been speculated that an assumed lack of evidence for palaeo wildfires during the triassic should be explained by a large drop in atmospheric oxygen concentration following or during the end permian mass extinction event preventing the occurrence of wildfires however evidence for palaeo wildfires is relatively common in many middle and late triassic strata whereas such evidence is almost totally lacking from early triassic sediments the interpretation of this charcoal gap or depression is difficult as many factors e g atmospheric oxygen concentration taphonomical biases lack of sediments suitable for the preservation of macroscopic charcoal lack of fuel and ignorance of scientists may have influenced not only the production but also the preservation and recovery of evidence for palaeo wildfires during this period thus it is not clear whether this early triassic charcoal gap can also be seen as evidence for an assumed wildfire gap or not without any doubt further investigations on the early triassic record of charcoal and other evidence for palaeo wildfires will be necessary before this problem can be solved in fact it can be expected that the number of published records of early triassic evidence for palaeo wildfires will increase in the future as more and more scientist working on sediments of this age may become aware of the interest in fires from this time this will certainly make it possible to give a much better picture of the temporal and regional distribution of wildfires during this period in the future

deformation due to geothermal exploitation at reykjanes iceland abstract ground deformation in utilized geothermal areas is often attributed either to pressure decrease or temperature decrease in the geothermal reservoir a new geothermal power plant at reykjanes began operation in may 2006 and local deformation caused by geothermal utilization was observed shortly thereafter we use images acquired by the envisat and terrasar x tsx satellites between 2003 and 2016 as well as available gnss data to derive constraints on the cumulative ground displacement at the reykjanes geothermal area iceland and compare these results to production data acquired from observation wells in this region we employ interferometric analysis of synthetic aperture satellite radar images insar using a combined persistent scatterer and small baseline approach on both ascending and descending envisat and tsx satellite tracks covering the 2003 2016 period time series of range change along line of sight los from the ground to the satellite show the characteristics of on going ground deflation in the vicinity of the reykjanes power plant in the 2005 2008 period the main area of deformation was 4 km long by 2 5 km wide aligned along the reykjanes fissure swarm but in the period 2009 2016 it is more circular in shape and 2 km wide los displacement rates have remained relatively steady in time although slightly faster in the 2005 2008 period than the 2009 2016 period the average los velocities from ascending and descending tracks are decomposed into estimates of near vertical and near east displacements the inferred maximum subsidence since the start of production is 260 mm horizontal displacements show contraction towards the center of deflation of up to 140 mm geodetic modeling is undertaken using sources of simple geometry within an elastic halfspace to determine the optimal sources for the observed contraction throughout 2005 2016 for the earlier period modeled utilizing envisat interferograms 16 june 2005 16 august 2008 the optimal source is a yang model with a strike of 58 and a source depth of 2 2 km the calculated volume change associated with the observed contraction is 2 3 106 m3 for the latter period utilizing tsx interferograms 24 september 2009 17 august 2016 the preferred source is a mogi type model at a depth of 1 2 km and the modeled volume change is 1 106 m3

deformation at krafla and bjarnarflag geothermal areas northern volcanic zone of iceland 1993 2015 abstract the krafla volcanic system has geothermal areas within the krafla caldera and at bjarnarflag in the krafla fissure swarm 9 km south of the krafla caldera arrays of boreholes extract geothermal fluids for power plants in both areas we collected and analyzed insar gps and leveling data spanning 1993 2015 in order to investigate crustal deformation in these areas the volcanic zone hosting the geothermal areas is also subject to large scale regional deformation processes including plate spreading and deflation of the krafla volcanic system these deformation processes have to be taken into account in order to isolate the geothermal deformation signal plate spreading produces the largest horizontal displacements but the regional deformation pattern also suggests readjustment of the krafla system at depth after the 1975 1984 krafla rifting episode observed deformation can be fit by an inflation source at about 20 km depth north of krafla and a deflation source at similar depth directly below the krafla caldera deflation signal along the fissure swarm can be reproduced by a 1 km wide sill at 4 km depth closing by 2 4 cm per year these sources are considered to approximate the combined effects of vertical deformation associated with plate spreading and post rifting response local deformation at the geothermal areas is well resolved in addition to these signals insar shows that deformation at bjarnarflag is elongated along the direction of the krafla fissure swarm 4 km by 2 km while it is circular at krafla 5 km diameter rates of deflation at krafla and bjarnarflag geothermal areas have been relatively steady average volume decrease of about 6 6 10 5 m 3 yr for krafla and 3 9 10 5 m 3 yr for bjanarflag are found at sources located at 1 5 km depth when interpreted by a spherical point source of pressure this volume change represents about 8 10 3 m 3 ton of the mass of geothermal fluid extracted per year indicating important renewal of the geothermal reservoir by water flow

geochemistry and sedimentology of coal seams from the permian witbank coalfield south africa a means of identification abstract sedimentological investigations of the coal bearing vryheid formation karoo sequence in the witbank coalfield have revealed that coal peat deposition was associated with both marine and non marine palaeodepositional events at the terminal stage of peat accumulation swamps were inundated by marine transgressions which deposited mud and silt above the peat coal and these overlying sediments contain typical marine features glauconite associated with marine ichnofossil assemblages in similar stratigraphic positions elsewhere in the basin the peat swamps were invaded by basinward prograding non marine fluvial systems which deposited coarse sand and gravel over the peat these overlying sediments are coarse grained arkosic strata geochemical analysis of the no 2 no 4 and no 5 coal seems in the region were undertaken using instrumental neutron activation analysis inaa and x ray fluorescence spectrometry xrfs these analyses show that the geochemistry of the coal compliments the sedimentological interpretations elements which tend to be more concentrated in marine derived sediments e g boron chlorine lithium and bromine occur in greater concentrations in the top of coals overlain by marine strata than in coals overlain by non marine fluvial sequences the latter do not show enrichments of these elements trace element composition of the coal seams was further utilized as means of identifying the seams using multivariant discriminant analysis each coal seam plot in a specific field thereby permitting its identification based on the trace element content if unknown areas of the coalfield are being explored a knowledge of the palaeodepositional stratigraphic sequences together with quantitative geochemical analyses could permit rapid identification of the coals concerned

distribution of selected trace elements in density fractionated waterberg coals from south africa abstract the waterberg coalfield located in the limpopo province north western area of south africa contains a significant proportion of the south african coal resource this permian coalfield typically contains high vitrinite high ash coals in the kungurian grootegeluk formation and high inertinite low ash coals in the artinskian vryheid formation four run of mine coals and density fractioned samples were analysed to determine their trace element content the concentrations of most trace elements in the run of mine coals exceed the global averages and certain global ranges and generally exceed values reported for other south african coalfields specifically hg concentrations are high to very high in all the coals up to 2 43 ppm in a sample from the vryheid formation cd and se concentrations are comparable to or lower than global averages and as is very low in the vryheid formation 1 57 ppm a sample from the grootegeluk formation is enriched in siderophile elements and a sample from the vryheid formation is depleted in chalcophile elements studies of the density fractionated samples indicate that cd exhibits an organic affinity in the grootegeluk formation samples and possibly a pyritic or sulphide affinity in the vryheid formation sample selenium has a greater affinity for the middle clay rich density fractions in all samples arsenic reports to the mineral rich sink fractions specifically the fractions enriched in pyrite mercury reports to both the float and sink fractions indicating an organic and inorganic affinity in these coals although there is more enrichment in the sink fractions in the grootegeluk formation samples and a definite organic correlation in the vryheid formation sample

inversion of synthetic aperture radar interferograms for sourcesof production related subsidence at the dixie valley geothermalfield we used synthetic aperture radar interferograms to imageground subsidence that occurred over the dixie valley geothermal fieldduring different time intervals between 1992 and 1997 linear elasticinversion of the subsidence that occurred between april 1996 and march 1997 revealed that the dominant sources of deformation during this timeperiod were large changes in fluid volumes at shallow depths within thevalley fill above the reservoir the distributions of subsidence andsubsurface volume change support a model in which reduction in pressureand volume of hot water discharging into the valley fill from localizedupflow along the stillwater range frontal fault is caused by drawdownwithin the upflow zone resulting from geothermal production our resultsalso suggest that an additional source of fluid volume reduction in theshallow valley fill might be similar drawdown within piedmont faultzones shallow groundwater flow in the vicinity of the field appears tobe controlled on the nw by a mapped fault and to the sw by a lineament ofas yet unknown origin

the burning of gondwana permian fires on the southern continent a palaeobotanical approach abstract fossil charcoal has widely been accepted as a direct indicator for the occurrence of palaeo wildfires in upper palaeozoic sediments of euramerica and cathaysia records of these remains are relatively common and regionally and stratigraphically more or less homogeneously distributed in terrestrial sequences on the other hand just a few records have been published for the permian of gondwana and only recently has it been demonstrated that macroscopic charcoals are also common here most permian macroscopic charcoal from gondwana is gymnospermous and has been reported from coal bearing strata macroscopic charcoal occurrences are spread out in different sequences and also in distinct stratigraphic intervals in the permian e g parana basin sakmarian artinskian of brazil karoo basin artinskian of south africa damodar basin lopingian of india and dead sea area changhsingian of jordan they range from peri glacial post glacial to warm temperate climatic systems throughout the permian macro and micro charcoal occurrences are compared to inertinite incidences to support the pyrogenic origin for these coal macerals and to provide an up to date overview on the known evidences of permian wildfires on gondwana in space and time

the petrography mineralogy and geochemistry of a paleocene lignite from southern saskatchewan canada abstract the coal petrology mineralogy and elemental composition was determined on the 5 m thick lignite of the estevan seam bienfait mine southwest saskatchewan organic petrology reveals a dominance of huminite macerals 73 with minor liptinite 7 and inertinite 11 macerals the maceral assemblage and the banded nature of the coal suggests a forest moor depositional environment for the lignite optical and scanning electron microscopy and x ray diffraction reveals that the dominant mineralogy of the coal is quartz and carbonates with minor sulfates the roof parting and floor rock are dominated by quartz and clays with minor feldspars elemental concentration is rather uniform with depth most elements are associated with the mineral matter and increase with increasing ash content the elements b na sr and br are associated with the organic portion of the coal some elements show both a mineral and organic association as ba co fe mo ce dy lu w u the high concentrations of certain elements na b ca is attributed to groundwater circulation which can both introduce and remove elements from the porous lignite

monitoring deformation at the geysers geothermal field california using c band and x band interferometric synthetic aperture radar monitoring deformation at the geysers geothermal field california using c band and x band interferometric synthetic aperture radar d w vasco jonny rutqvist alessandro ferretti alessio rucci fernando bellotti patrick dobson curtis oldenburg julio garcia mark walters and craig hartline d w vasco jonny rutqvist patrick dobson curtis oldenburg earth sciences di vision building 74 berkeley laboratory 1 cyclotron road berkeley ca 94720 e mail dwvasco lbl gov jrutqvist lbl gov pfdobson lbl gov cmoldenburg lbl gov alessandro ferretti alessio rucci and fernando bellotti tele rilevamento europa via vittoria colonna 7 20149 milano italy e mail alessandro ferretti treuropa com alessio rucci treuropa com fernando bellotti treuropa com julio garcia mark walters and craig hartline calpine corporation 10350 socrates mine road middletown ca 95461 e mail julio garcia calpine com mark walters calpine com craig hartline calpine com

ground deformation due to steam cap processes at reykjanes sw iceland effects of geothermal exploitation inferred from interferometric analysis of sentinel 1 images 2015 2017

mineral matter and potentially hazardous trace elements in coals from qianxi fault depression area in southwestern guizhou china mineralogy coal chemistry and 21 potentially hazardous trace elements phtes of 44 coal samples from the qianxi fault depression area qfda in southwestern guizhou province china have been systematically studied the major minerals in coals studied are quartz kaolinite illite pyrite calcite smectite marcasite and accessory minerals including rutile dolomite siderite gypsum chlorite melanterite apatite collophane and florencite the sio2 content shows a broad variation 0 8 30 7 a high sio2 content in late permian coals reflects their enrichment in quartz the al2o3 content varies from 0 8 to 13 4 fe2o3 from 0 2 to 14 6 cao from al k ti na mg ca fe s a comparison with world coal averages shows that the late permian coals in qfda are highly enriched in as hg f and u and are slightly enriched in mo se th v and zn the late triassic coals in qfda are highly enriched in as and hg and are slightly enriched in mo th and u the concentrations of as hg mo se tl and zn in the qfda coal are higher than other guizhou coal and liupanshui coal nearby the qfda is an area strongly affected by the low temperature hydrothermal activity during its geologic history yanshanian age about 189 ma the coals in qfda are enriched in volatile phtes including as hg se sb mo among others the regions where the coals are enriched in as hg and f have been mapped the regions of coals enriched in volatile phtes overlap with the regions of noble metal ore deposits these coals are located in the cores of anticline and anticlinorium which are connected with the profound faults through the normal faults coals are enriched in volatile phtes as a result of the low temperature hydrothermal activity associated with tectonic faulting

geochemistry of coals from the elk valley coalfield british columbia canada abstract the elk valley coalfield of british columbia is one of the major coal producing areas in canada the coals are of cretaceous and jurassic cretaceous age and range in rank from high volatile to low volatile bituminous romax 0 8 1 6 coal seams from outcrops and active mines in this coalfield were analysed for rank and maceral composition using reflected light microscopy for geochemistry using aas inaa and icpes and also by proximate and ultimate analyses the elk valley coal seams contain low average concentrations of hazardous elements such as as mo pb and se however there are seams that contain relatively high concentrations of some of these elements such as 8 mg kg and 108 mg kg of arsenic when the geochemistry of coal seams is compared within the different parts of the coalfield the elemental composition amongst the seams from various sections located in the central area of the coalfield is similar coal seams in the northern area of the coalfield have different geochemistry than coal seams in other areas of the coalfield seams in the northern area have much higher as br cr cu fe k and na content but contain less ca

structural characterization of vitrinite rich and inertinite rich permian aged south african bituminous coals abstract two south african coals of the same rank and age but different in maceral composition were subjected to extensive structural analyses inertinite rich highveld coal dominated by semifusinite and vitrinite rich waterberg coal were studied to determine structural differences and similarities the two coals had similar carbon content 84 dmmf and vitrinite reflectance mean maximum 0 71 for vitrinite rich vs 0 75 for inertinite rich but differed in hydrogen content 6 23 for vitrinite rich and 4 53 for inertinite rich the inertinite rich coal was more aromatic 86 for inertinite rich and 76 for vitrinite rich and more polycondensed indicated by a higher bridgehead carbon content the inertinite rich coal was structurally more ordered with a higher degree of crystalline stacking both coals had similar average aromatic cluster sizes 16 carbons for vitrinite rich and 18 carbons for inertinite rich and number of cluster attachments 6 attachments for vitrinite rich and 5 attachments for inertinite rich mass spectrometry showed that both coals consist of similar molecular weight distributions ranging to approximately 1700 m z with a maximum abundance of 450 m z for the vitrinite rich coal and 550 m z for the inertinite rich coal compared to the argonne premium coals the south african vitrinite rich waterberg coal was comparable to the coals in the high volatile bituminous range and inertinite rich highveld was closer to the medium to low volatile bituminous range both coals were surprisingly similar in bulk characterization although inertinite rich highveld coal was structurally more ordered hydrogen deficient and more aromatic

high chromium contents in tertiary coal deposits of northwestern washington a key to their depositional history abstract chromium contents obtained from 20 coal and 5 associated rock samples collected from the basal part of the eocene chuckanut formation in skagit and whatcom counties northwest washington range between 30 and 300 ppm mean 120 ppm whole coal basis the lenticular coals ranging in rank from subbituminous to anthracite and with an ash content of 12 46 crop out along the western flank of the cascade range results of x ray diffraction analysis of low temperature ash show that the mineral matter in the coal samples consists predominantly of quartz and clay kaolinite illite and chlorite group however accessory minerals isolated from the coal samples and analyzed by x ray diffraction scanning electron microscope and optical methods contain angular fragments and euhedral crystals of the spinel group chromite magnetite and trevorite kaolinite serpentine group antigorite and chrysotile chlorite group amphibole group and pyroxene group minerals augite diopside and enstatite all of which are commonly enriched in chromium although associated primarily with the inorganic fraction of the coal concentrations of chromium in the samples show no statistically significant correlation with ash content localized concentrations of chromium in the coal are the result of natural contamination from the alteration of detrital chromium bearing mineral grains introduced into the peat forming mires from nearby jurassic ophiolite bodies the coals formed in the early eocene in rapidly subsiding small basins that developed during the uplift and erosion of the pre tertiary ophiolite terrain scattered bodies of source rock random distribution of chromium bearing minerals within the coal and sample heterogeneity account for the variation in cr contents of the samples

minerals and potentially hazardous trace elements in the late triassic coals from the qiangtang basin china abstract the tumen coal mine has the largest coal resources in tibet which have been developed and utilized as an important energy source in the last decades it has raised some health problems during the coal exploration and utilization in tibet fifty late triassic coal or coaly samples were picked up from the qiangtang basin tumen mine woruoshan and hongshuihe areas to determine the minerals potentially hazardous elements and their mode of occurrence and possible sources coal samples from the qiangtang basin have medium and high ash yields 15 20 47 88 with low or medium high total sulfur content 0 04 4 86 minerals in qiangtang basin coal include clay minerals dolomite quartz pyrite siderite and hematite and trace amounts of halite feldspar anhydrite barite chromite and galena potentially hazardous trace elements in coal samples include as hg pb and se arsenic is controlled mainly by aluminosilicate minerals mercury occurs mainly as an organic bound form the organically bound pb is dominant selenium is controlled mainly by fe bearing probably pyrite a proportion of the elevated concentrations of as hg pb and se in qiangtang basin coal may be related to underlying shale bed these elements might have been eroded or leached from the shale bed which were subsequently transported and accumulated syngenetically in the coal forming peat swamps the enrichment of as hg pb and se in qiangtang basin coal however is also partly to be related to magmatic hydrothermal fluids

rupture propagation behavior and the largest possible earthquake induced by fluid injection into deep reservoirs earthquakes caused by fluid injection into deep underground reservoirs constitute an increasingly recognized risk to populations and infrastructure quantitative assessment of induced seismic hazard however requires estimating the maximum possible magnitude earthquake that may be induced during fluid injection here i seek constraints on an upper limit for the largest possible earthquake using source physics simulations that consider rate and state friction and hydro mechanical interaction along a straight homogeneous fault depending on the orientation of the pressurized fault in the ambient stress field different rupture behavior can occur 1 uncontrolled rupture front propagation beyond the pressure front or 2 rupture front propagation arresting at the pressure front in the first case fault properties determine the earthquake magnitude and the upper magnitude limit may be similar to natural earthquakes in the second case the maximum magnitude can be controlled by carefully designing and monitoring injection and thus restricting the pressurized fault area

analysis of fluid injection induced fault reactivation and seismic slip in geothermal reservoirs we explore the issue of fault reactivation induced in enhanced geothermal systems by fluid injection specifically we investigate the role of late stage activation by thermal drawdown a thermal hydrological mechanical simulator incorporating a ubiquitous joint constitutive model is used to systematically simulate the seismic slip of an embedded critically stressed strike slip fault we examine the effects of both pore pressure perturbation and thermal shrinkage stress on the magnitude of the resulting events and timing we analyze the sensitivity of event magnitude and timing to changes in the permeability of the fault and fractured host fracture spacing injection temperature and fault stress obliquity from this we determine that 1 the fault permeability does not affect the timing of the events nor their size since fluid transmission and cooling rate are controlled by the permeability of the host formation 2 when the fractured medium permeability is reduced from 10 13 to 10 16 m2 the timing of the event is proportionately delayed by a corresponding 3 orders of magnitude 3 injection temperature only influences the magnitude but not the timing of the secondary thermal event the larger the temperature differences between that of the injected fluid and the ambient rock the larger the magnitude of the secondary slip event 4 for equivalent permeabilities changing the fracture spacing 10 m 50 m 100 m primarily influences the rate of heat energy transfer and thermal drawdown within the reservoir smaller spacing between fractures results in more rapid thermal recovery but does not significantly influence the timing of the secondary thermal rupture

the occurrence of potentially hazardous trace elements in five highveld coals south africa abstract permian coals of the southern hemisphere are generally considered to contain lower concentrations of sulfides halogens and trace elements when compared to northern hemisphere carboniferous coals few studies have considered the trace element content in south african coals and little or no work has been published for highveld coals of the nineteen coal fields in south africa the highveld coal field is one of the nine currently producing and is second largest in terms of production five run of mine samples and a high ash middlings product from the number 4 lower seam were analyzed totaling six sample sets fourteen trace elements as cd co cr cu hg mn mo ni pb sb se v and zn were selected for this study based on the global perception that these elements may be hazardous to human health and or the environment when they are released during coal utilization several sample preparation techniques were tested using certified reference materials sarms 18 19 and 20 to determine the most repeatable technique for these coals the samples were analyzed by icp aes and cvaa hg only microwave digestion proved to be generally unreliable despite the utilization of several different methods a slurry direct injection method into the icp aes provided good correlations with the reference material but requires further development to enhance the confidence level in this relatively unexplored technique samples prepared based on three astm standards for the determination of trace elements in coal provided repeatable results in most instances and were the preparation methods utilized for the highveld coals the trace element values determined for the highveld coals are generally in good agreement with values available in literature for south african coals with the exception of hg mn and cr hg values reported here are lower cr and mn higher results generally agree well with analyses on the same samples conducted by the united states geological survey when considering the global ranges for trace elements the highveld range values are within swaine s range boundaries with the exception of cr compared to the cited global average values for the fourteen trace elements determined the values obtained for the highveld coals generally fall below or well below these average values with the exception of cr and mn concentrations of cd and cu are lower compared to global average values and as mo pb se sb and zn can be considered low to very low arsenic is ten times lower compared to typical usa values concentrations of co and ni are similar to global averages with v and hg being very slightly higher the middlings samples reported higher concentrations of most elements related to the higher ash content of these samples of interest the chalcophile elements determined are all depleted in the highveld coals compared to global averages and the siderophile elements are enriched or comparable to global averages risk based health studies in the usa on coals with similar or higher hg and significantly higher as contents have not reported negative health effects and therefore it could be assumed that the mobilization of these trace elements from the five highveld coals are unlikely to cause human health problems work is ongoing to determine the modes of occurrence of these haps and to address the partitioning behaviors and speciation states of these elements during coal utilization

deformation and seismicity in the coso geothermal area inyo county california observations and modeling using satellite radar interferometry interferometric synthetic aperture radar insar data collected in the coso geothermal area eastern california during 1993 1999 indicate ground subsidence over a 50 km 2 region that approximately coincides with the production area of the coso geothermal plant the maximum subsidence rate in the peak of the anomaly is 3 5 cm yr 1 and the average volumetric rate of subsidence is of the order of 10 6 m 3 yr 1 the radar interferograms reveal a complex deformation pattern with at least two irregular subsidence peaks in the northern part of the anomaly and a region of relative uplift on the south we invert the insar displacement data for the positions geometry and relative strengths of the deformation sources at depth using a nonlinear least squares minimization algorithm we use elastic solutions for a prolate uniformly pressurized spheroidal cavity in a semi infinite body as basis functions for our inversions source depths inferred from our simulations range from 1 to 3 km which corresponds to the production depths of the coso geothermal plant underpressures in the geothermal reservoir inferred from the inversion are of the order of 0 1 1 mpa except a few abnormally high underpressures that are apparently biased toward the small source dimensions analysis of the insar data covering consecutive time intervals indicates that the depths and or horizontal extent of the deformation sources may increase with time this increase presumably reflects increasing volumes of the subsurface reservoir affected by the geothermal exploitation we show that clusters of microearthquakes associated with the geothermal power operation may result from perturbations in the pore fluid pressure as well as normal and shear stresses caused by the deflation of the geothermal reservoir

modes of occurrence of mercury and other trace elements in coals from the warrior field black warrior basin northwestern alabama abstract the mineralogic residence and abundance of trace metals is an important environmental issue data from the usgs coal quality database show that potentially toxic elements including hg as mo se cu and tl are enriched in a subset of coal samples in the black warrior basin of alabama usa although the coal as mined typically is low in these elements localized enrichments occur in high pyrite coals and near faults microscopic analyses demonstrate that the residence of these elements is dominantly in a late stage pyrite associated with structurally disrupted coal further our data suggest addition of hg to the coal matrix as well the source of these trace elements was hydrothermal fluids driven into the black warrior basin by alleghanian age tectonism

minerals and potentially hazardous trace elements in marine oil shale new insights from the shengli river north surface mine northern tibet china the shengli river changshe mountain oil shale zone including the changliang mountain shengli river oil shale the shengli river north oil shale and the changshe mountain oil shale represents potentially the largest marine oil shale resource in china new geochemical data from the shengli river north oil shale are presented to evaluate potentially hazardous trace elements in oil shale and to discuss possible factors controlling the geochemical anomalies oil shale samples from the shengli river north area are characterized by high ash yield 59 25 66 27 and toc content 4 77 9 35 with low total sulfur content 0 1 1 56 and intermediate shale oil content 3 60 16 30 minerals in the shengli river north oil shale include calcite clay minerals quartz dolomite and fe bearing minerals e g pyrite limonite and hematite and trace amounts of zeolite apatite and barite potentially hazardous trace elements in oil shale samples include as se mo f ni cd and hg arsenic is present probably in both organic and inorganic matter selenium is controlled mainly by fe bearing probably pyrite while f and cd occur mainly as apatite the organically bound mo and ni are dominant and hg probably occurs as a substitution in the structure of pyrite apatite and calcite the elevated concentrations of f and cd in the shengli river north oil shale may be related to sediment source water chemistry may have played an important role for ni and mo enrichments while the enrichment of se in the oil shale samples is possibly related to hydrothermal fluids other elements including hg and as are probably related to several factors

geological and geochemical characteristics of high arsenic coals from endemic arsenosis areas in southwestern guizhou province china southwest guizhou province is one of the most important areas of disseminated sediment hosted type au deposits in china and is an important area of coal production the chemistry of most of the coals in sw guizhou is similar to those in other parts of china their as content is near the chinese coal average but some local small coal mines contain high as coals the highest as content is up to 3 5 wt in the coal the use of high as coals has caused in excess of 3000 cases of as poisoning in several villages the high as coals are in the longtan formation which is an alternating marine facies and terrestrial facies the coals are distributed on both sides of faults that parallel the regional anticlinal axis the as content of coal is higher closer to the fault plane the as content of coal changes greatly in different coal beds and different locations of the same bed geological structures such as anticlines faults and sedimentary strata control the distribution of high as coals small au deposits as well as sb hg and th mineralization are found near the high as coals although some as bearing minerals such as pyrite arsenopyrite realgar as bearing sulfate as bearing clays and phosphate are found in the high as coals their contents cannot account for the abundance of as in some coals analysis of the coal indicates that as mainly exists in the form of as5 and as3 perhaps combined with organic compounds the occurrence of such exceptionally high as contents in coal and the fact that the as is dominantly organically associated are unique observations

an integrated perspective of the continuum between earthquakes and slow slip phenomena slow slip a mechanism by which faults can relieve stress was thought to be distinct from earthquakes however a global review of slow slip phenomena suggests that instead there is a continuum between the two types of event