geochemical and mineralogical evidence for a coal hosted uranium deposit in the yili basin xinjiang northwestern china abstract the petrological geochemical and mineralogical compositions of the coal hosted jurassic uranium ore deposit in the yili basin of xinjiang province northwestern china were investigated using optical microscopy and field emission scanning electron microscopy in conjunction with an energy dispersive x ray spectrometer as well as x ray powder diffraction x ray fluorescence and inductively coupled plasma mass spectrometry the yili coal is of high volatile c b bituminous rank 0 51 0 59 vitrinite reflectance and has a medium sulfur content 1 32 on average fusinite and semifusinite generally dominate the maceral assemblage which exhibits forms suggesting fire driven formation of those macerals together with forms suggesting degradation of wood followed by burning the yili coals are characterized by high concentrations of u up to 7207 g g se up to 253 g g mo 1248 g g and re up to 34 g g as well as as up to 234 g g and hg up to 3858 ng g relative to the upper continental crust the rare earth elements rees in the coals are characterized by heavy or and medium ree enrichment the minerals in the yili coals are mainly quartz kaolinite illite and illite smectite as well as to a lesser extent k feldspar chlorite pyrite and trace amounts of calcite dolomite amphibole millerite chalcopyrite cattierite siegenite ferroselite krutaite eskebornite pitchblende coffinite silicorhabdophane and zircon the enrichment and modes of occurrence of the trace elements and also of the minerals in the coal are attributed to derivation from a sediment source region of felsic and intermediate petrological composition and to two different later stage solutions a u se mo re rich infiltrational and a hg as rich exfiltrational volcanogenic solution the main elements with high enrichment factors u se as and hg overall exhibit a mixed organic inorganic affinity the uranium minerals pitchblende and coffinite occur as cavity fillings in structured inertinite macerals selenium as and hg in high pyrite samples mainly show a sulfide affinity

densification of polar snow measurements modeling and implications for altimetry density profiles in the upper 10 14 m of snow have been measured along a 500 km traverse across the greenland ice sheet using a neutron scattering technique repeat measurements over periods ranging from a few days to 5 years allow strain rates to be determined as a function of depth very large strain rates are observed in the surface layer of snow over summer periods in the underlying multiyear snow strain rate decreases with decreasing porosity however once this effect has been removed the effect of increasing overburden pressure is counteracted by increasing strength of the material there are fluctuations in strain rate associated with the annual layering which indicate that winter and summer snow have different strengths based on these observations we derive a new densification equation which includes the effect of snow density and snow type and the effect of temperature described by an arrhenius expression with activation energy of the order of 110 kj mol 1 and an exponential prefactor determined simply by the temperature history of the snow for multiyear snow and meteorological conditions that do not vary from year to year our equation reduces to a form similar to the herron and langway equation for first stage densification using the new equation we calculate the sensitivity of compaction rate to short term fluctuations in temperature and accumulation as 0 11 0 20 m a 1 k 1 and 0 33 0 95 m a 1 meters water equivalent 1 respectively and discuss the consequent uncertainty in satellite measurements of the long term elevation trend in this area of the greenland ice sheet

raman microspectroscopy of funginite from the upper silesian coal basin poland abstract raman spectral characteristics of funginite were compared with that of fusinite and semifusinite from the same coals inertinite concentrates prepared from four samples of coking coals from the upper silesian coal basin of poland were examined the examination reveals that funginite spectral characteristics have common features with that of fusinite or to smaller extent to semifusinite this suggests that the high reflectance of funginite might result from charring during wildfire activity

measurement of snow density and microstructure using computed tomography in the past two dimensional images of internal snow structure have been obtained through plane surface sections or thin sections these techniques are time consuming and necessarily destroy the snow specimen computed tomography ct allows similar images to be obtained but in a more efficient and non destructive manner to demonstrate the methodology a ct scanner was used to obtain cross sectional images over time of a snow sample undergoing kinetic growth metamorphism densities calculated from the ct images correlated well to density measured using a traditional method a procedure was developed that allows the ct image to be converted to binary in an objective manner employing innovative stereological software the microstructural properties grain diameter bond diameter neck length and intercept length of the snow were then measured from the two dimensional ct images the presented methodology provides significant improvements over previous techniques requiring less time and labor to obtain high quality microstructural data

revisiting coos bay oregon a re examination of funginite huminite relationships in eocene subbituminous coals coal petrography has advanced significantly since reinhardt theissen and james schopf pioneered the use of thin sections to examine coals from coos bay oregon and to many coal petrographers the nomenclature used in that study is irrelevant the schopf 1947 study was a ground breaking examination of maceral relationships that need to be part of the working vocabulary of modern petrographers to support this a re examination of the coos bay thin section collection was undertaken using modern nomenclature for low rank coals under reflected light this particular collection was chosen in part because of the abundance of fungal material reported by schopf fungal material in coal and its association with huminite vitrinite macerals provides important information about the decompositional history of the coal and allows coal dominated by oxic processes to be differentiated from coal dominated by anoxic processes in the coos bay samples predominantly oxic intervals contain well preserved fungi including spores sclerotia and hyphae while anoxic intervals contain no fungi

density log of a 181 m long ice core from berkner island antarctica a 181 m long ice core was drilled at 79 36 51 s 45 43 28 w near the summit of berkner island antarctica 886 m a s l berkner island is located between the filchner and ronne ice shelves and the ice near the summit shows little lateral flow the density of the ice core was measured every 3 mm along its length using attenuation of a gamma ray beam which gave an absolute accuracy of 2 as expected there is a general density increase with depth the maximum densities of 900 kg m 3 being reached just above 100 m depth comparison with the electrical conductivity method ecm shows density variations with the same wavelength as the annual signals which can be seen in the ecm log higher acidity during summer in the shallowest part of the core the density of winter layers is higher than that of summer layers a relationship which is reversed at greater depth we assume that the densification rates for the two types of firn are different similar density phenomena were observed on ice cores from greenland showing that such phenomena are not a local effect

coal modeling using markov chain and monte carlo simulation analysis of microlithotype and lithotype succession abstract markov chain analysis was applied to the description of the megascopic lithologic transitions in pennsylvanian age eastern kentucky coals coal lithology modeling can be problematic as individual lithotypes can represent near instantaneous events vitrain prolonged degradation durain or fire induced loss of previously deposited lithologies fusain each of the latter lithotypes potentially representing vastly different amounts of time could be of the same thickness therefore equal thickness does not necessarily imply equal time probability transform matrices that employ uniform lithotype thicknesses were used allowing transitions between like lithotypes embedded markov chains thereby only considering transitions between different lithotypes and continuous time markov chains were employed in the assessment of a section of the no 5 block coal pennsylvanian breathitt group martin county kentucky embedded markov chains could successfully simulate the lithologic transitions a monte carlo random process was programmed to simulate thickness variations of lithotypes between the transitions the proposed hybrid model of monte carlo markov chain was able to predict the random pattern that underlies lithotypes transitions and thickness the hybrid monte carlo markov chain technique proved to be effective in the case study in simulating both the lithologic thickness variations and transitions

compositional variation and palaeoenvironment of the volcanolithic fort cooper coal measures bowen basin australia abstract an integrated analysis of megascopic lithotype microscopic maceral and mineral composition stable carbon isotope and interburden sedimentology from a single well was used to interpret the response of the late permian fort cooper coal measures fccm to regional and global environmental influences the fccm are differentiated from underlying relatively high vitrinite moranbah coal measures and overlying higher inertinite rangal coal measures in the bowen basin by their intercalation with abundant tuff and siliciclastic partings and interbeds besides this there is little described about the variation in the organic composition of the fccm and its causes the fccm can be subdivided into a lower aggradational fair hill formation transgressed by the shallow marine derived black alley shale that interfinger with is overlain by the progradational middle main seams and burngrove formation coal measures the coals are dominantly dull with minor bright bands that are more abundant in the burngrove formation representing a change in plant composition the maceral analysis shows that the coals in the fair hill formation and middle main seams are vitrinite rich 80 90 mmf albeit with high mineral matter suggesting the formation of precursory peat under rising water levels and with high sediment tuff influx and preservation the coals in the burngrove formation have an increased inertinite content 30 mmf but are also high in mineral matter suggesting a shift to increased decomposition arising from a fluctuating water table possibly increased aridity and or microbial activity tuffs occur throughout and although their frequency is higher in the lower fair hill formation the preservation of thicker tuffs in the upper burngrove formation indicates increased intensity of volcanism that could have modified the environment variation in carbon isotope compositions show a parabolic trend from around 24 1 in the fair hill formation to more variable values in the middle main seams with an overall 13 c enrichment upwards in the burngrove formation prior to the 13 c values becoming negative depleted between 1 to 4 from the average 24 1 in the top seams and into the overlying rangal coal measures the 13 c depletion trend in the upper part of the section is unexpected in view of corresponding increase in inertinite content of the coals indicating that the 13 c values plant composition and inertinite content are decoupled unless the inertinite origin is from intense microbial decay similar stable carbon isotope depletion trends have been observed elsewhere in an equivalent stratigraphic interval of the bowen basin suggesting that the carbon isotope values are responding to global conditions that cause negative excursions in carbon isotopes before the p t boundary overall the basin was continuously subsiding and peats accumulated with constant interruptions from excessive sedimentation and volcanic eruptions the low proportion of visible thick bright bands coupled with high telovitrinite mmf content suggests a marsh to fen environment with an open canopy and ponding able to preserve volcanic ash falls

notes on the origin of the resinite rich pine needle lithotype of the cretaceous cambria coal weston county wyoming abstract the cretaceous cambria coal located in the western part of the black hills in weston county wyoming was mined in the late 1800 s and early 1900 s primarily to serve the burlington and missouri river railroad on its route from lincoln nebraska to billings montana the coal bed contains a distinctive resinite rich lithotype commonly known as the pine needle coal the coal is characterized by a collodetrinite inertodetrinite liptodetrinite lithotype and the liptodetrinite including the resinite represents a degraded residue of what was originally a deposit with a greater representation of wood derived material

assessing a multilayered dynamic firn compaction model for greenland with asiras radar measurements a method to assess firn compaction using data collected with the airborne sar synthetic aperture radar interferometric radar altimeter system asiras is developed for this we develop a dynamical firn compaction model that includes meltwater retention based on the asiras data which show internal layers as annual horizons in the uppermost firn the method relies on inferring the age depth internal layers information from the radar data using a monte carlo inversion technique to tune in parallel both the firn model and the atmospheric forcing parameters temperature and accumulation the model is validated against two firn cores and it is shown that applying both firn densities and age depth information for the inversion gives the most accurate understanding of model biases the method is then applied to a 67 km section of the egig line forced by atmospheric output from a regional climate model using only age depth information in the inversion step the layers traced by the asiras data are modeled with a root mean square error of 9 cm which is within the estimated error of the layer tracing this gives us confidence in applying observed annual layering from firn radar data to assess firn compaction however the study also indicates that our firn model tuning parameters are site dependent and cannot be parameterized by temperature and accumulation alone

joint probabilistic petrophysics seismic inversion based on gaussian mixture and markov chain prior models abstractseismic reservoir characterization focuses on the prediction of reservoir properties based on the available geophysical and petrophysical data the inverse problem generally includes continuous properties such as petrophysical and elastic attributes and discrete properties such as lithology fluid classes we have developed a joint probabilistic inversion methodology for the prediction of petrophysical and elastic properties and lithology fluid classes that combined statistical rock physics and bayesian seismic inversion the elastic attributes depend on continuous petrophysical variables such as porosity and clay content and discrete lithology fluid classes through a nonlinear rock physics relationship together the seismic model relates the elastic attributes such as velocities and density to their seismic response reflectivity traveltime and amplitudes the advantage of our integrated approach is that the inversion method accounts for the uncertainty associated to each step of the mo

sequence stratigraphic interpretation of peatland evolution in thick coal seams examples from yimin formation early cretaceous hailaer basin china abstract peat formed in mire settings sensitively records environmental fluctuations during deposition including changes in water table or base level and accommodation on this basis coal seams as geologically preserved peats can provide evidence of high resolution paleoclimatic fluctuations as well as paleobotanical evolution through periods of peat formation the no 2 and no 1 in ascending order thick coal seams from the early cretaceous yimin formation in the zhalainuoer coalfield hailaer basin ne china are investigated using sedimentological sequence stratigraphic and petrographic analyses to understand the evolution of their peat forming environments these single thick coal seams lacking siliciclasitic partings are well developed in the central area of the zhalainuoer coalfield petrographic analyses demonstrate that water table or base level fluctuations in single seams can be revealed by a number of significant surfaces formed by various events including paludification give up transgressive accommodation reversal flooding and exposure surfaces these surfaces can separate the single coal into a number of wetting up and drying up cycles the wetting up cycle is characterized by a gradual upward increasing trend in the huminite inertinite ratio and in the ash yields in contrast the rapid drying up cycle is characterized by an upward increasing trend in the inertinite dominated coal 46 on average that represents a phase of exposure and oxidation resulting from a falling water table this drying up cycle can be correlated with the scouring surface in landward parts of the basin and terrestrialization surface basinward the no 2 coal seam occurs in the transgressive systems tract and comprises three high frequency depositional sequences in which each coal cycle is characterized by a gradual wetting up cycle and ends with a rapid drying up cycle the no 1 coal seam occurs in the highstand system tract and consists of several high frequency depositional sequences in which each coal cycle is characterized by a gradual drying up cycle and ends with a rapid wetting up cycle these coals could also superpose to constitute the thick coal seam in which various sequence stratigraphic surfaces can be recognized including terrestrialization accommodation reversal and exposure surfaces stratigraphic relationships between coal and clastic components in the yimin formation enable us to demonstrate that thick coals span the formation of several coal cycles and high resolution boundaries allowing us to interpret the effects of accommodation on coal seam composition recognition that environmental changes can be recorded by thick coals has significance for studies that incorrectly suppose that peat or coal cycles can offer high resolution and time invariant records of paleoclimatic fluctuations and paleobotany evolution

petrology and palynology of the middle pennsylvanian leatherwood coal bed eastern kentucky indications for depositional environments abstract the eastern kentucky coal field is located in the central portion of the appalachian basin the pennsylvanian breathitt formation in this region is characterized by numerous sequences of bituminous coal bearing sedimentary rocks these coals have distinct maceral compositions due to variations in depositional environments coal characterization is an important method for determining conditions that influenced peat accumulation and overall depositional settings of mires this study focuses on the characterization of the maceral composition of the middle pennsylvanian age leatherwood coal bed it utilizes petrographical palynological and geochemical analyses to describe specific depositional environments and associated peat accumulation conditions petrographic analyses indicate that these coals have relatively high liptinite and varying inertinite content along with trace amounts of mineral matter vitrinite mainly in the form of collotelinite is the most dominant maceral group geochemical data reveals low ash and sulfur content ancillary palynological data shows the palynomorph assemblage to be dominated by tree fern and large lycopod tree spores with lesser amounts of small lycopod tree small fern and cordaites and calamites spores the petrographic geochemical and palynological data indicate that both domed ombrotrophic and planar rheotrophic mire conditions with limited local detrital influx contributed to the formation of the leatherwood coal

geochemical and petrographical characteristics of low rank balingian coal from sarawak malaysia its implications on depositional conditions and thermal maturity abstract geochemical and coal petrographical analyses were undertaken on low rank upper pliocene balingian coal from sarawak malaysia in an attempt to reconstruct the conditions during peat accumulation and the subsequent coalification processes chemically the coal in this study is characterised by high moisture low ash yield and low sulphur content the low ash yield and low sulphur content together with the lack of epiclastic partings clearly indicate that it was deposited in ombrotrophic raised bogs the coal was plotted in the type iii terrigenous kerogen zone of the van krevelen diagram with h c value below 0 9 this shows that the coal was derived from plant materials of terrigenous origin and is still immature for petroleum generation the petrographical study reveals nonetheless the expulsion of early generated hydrocarbons from the disintegration of suberinite and also from phlobaphinite and cutinite petrographically the coal is dominated by huminite with low to moderate amounts of liptinite and low amounts of inertinite pointing to predominantly anaerobic deposition conditions in the paleomires with limited thermal and oxidative tissue destruction most of the studied samples are characterised by low tpi and high gi values and are plotted on the marsh field of the diessel s diagram or it could also originate from decomposed wood in forested swamps nevertheless coals originating from both these sources usually generate high ash yield which is not the case for the studied coal this shows that the interpretation as suggested by the diessel s diagram is not valid for the studied coal the coal has a mean random huminite reflectance between 0 26 and 0 35 suggesting a lignite coal rank for the coal nevertheless geochemical classification based on total moisture and calorific value suggests a subbituminous c rank

densification of layered firn in the ice sheet at dome fuji antarctica in order to better understand the densification of polar firn firn cores from the three sites within 10 km of dome fuji antarctica were investigated using surrogates of density dielectric permittivities e v and e h at microwave frequencies with electrical fields in the vertical and horizontal planes respectively dielectric anisotropy e e v e h was then examined as a surrogate of the anisotropic geometry of firn we find that layered densification is explained as a result of complex effects of two phenomena that commonly occur at the three sites basically layers with initially smaller density and smaller geometrical anisotropy deform preferentially throughout the densification process due to textural effects second layers having a higher concentration of cl ions deform preferentially during a limited period from the near surface depths until smoothing out of layered cl ions by diffusion we hypothesize that cl ions dissociated from sea salts soften firn due to modulation of dislocation movement moreover firn differs markedly across the three sites in terms of strength of geometrical anisotropy mean rate of densification and density fluctuation we hypothesize that these differences are caused by textural effects resulting from differences in depositional conditions within various spatial scales

probabilistic petrophysical properties estimation integrating statistical rock physics with seismic inversion a joint estimation of petrophysical properties is proposed that combines statistical rock physics and bayesian seismic inversion because elastic attributes are correlated with petrophysical variables effective porosity clay content and water saturation and this physical link is associated with uncertainties the petrophysical properties estimation from seismic data can be seen as a bayesian inversion problem the purpose of this work was to develop a strategy for estimating the probability distributions of petrophysical parameters and litho fluid classes from seismics estimation of reservoir properties and the associated uncertainty was performed in three steps linearized seismic inversion to estimate the probabilities of elastic parameters probabilistic upscaling to include the scale changes effect and petrophysical inversion to estimate the probabilities of petrophysical variables andlitho fluid classes rock physics equations provide the linkbetween reservoir properties and velocities and lin

stable isotopes of organic carbon palynology and petrography of a thick low rank miocene coal within the mile basin yunnan province china implications for palaeoclimate and sedimentary conditions abstract coal contains detailed long term records of contemporaneous environment climate and subsequent diagenetic processes stable isotopes of carbon petrological palynological and mineralogical analyses were carried out on a 28 m thick low rank miocene coal seam from the mile basin yunnan province china for the purpose of deciphering the palaeoclimate and sedimentary conditions during peat deposition the coal is characterized by both pale and dark lithotypes palynological analyses show that both lithotypes are dominated by angiosperms which is interpreted to indicate a moderately warm climate the absence of fagus and taxodiaceae pollen suggests that there may have been dry periods during peat accumulation in general both fagus and taxodiaceae require a constant wet environment in order to proliferate organic petrography 13c and gypsum concentrations corroborate that there were alternating drier and wetter periods within the palaeomire during peat accumulation the fine scale variability in the 13c signature appears to be controlled by plant type angiosperm gymnosperm ratios and vegetation index are directly correlated with 13c isotopic values plant type however seems to be proximally controlled by water level angiosperms were more dominant during times of lower water table or less moist conditions interpreted to correspond to less negative values of 13c the correlation of greater concentrations of gypsum with less negative 13c values also supports drier conditions however in addition to the fine scale variability four larger scale cycles are defined based on less negative 13c values a less negative 13c isotopic signature demarcates the top of each of these cycles which represent spikes of lower water table and or drier conditions in addition a general correlation of the 13c variations in the studied coal seam with atmospheric co2 suggests that the atmosphere also had a significant influence on peat formation in the mile basin although the mile basin palaeomire accumulated over a long time an integrated approach to its analysis has demonstrated considerable variation in palaeoclimate changes in wetness dryness had a direct effect on the ecological composition of the palaeomire these floral changes would not have only been restricted to the palaeomire but most likely had a regional influence thus detailed analysis of coals can yield useful insightful and practical knowledge on past regional palaeoenvironmental conditions which can then be placed within a global context

three dimensional coordination number from two dimensional measurements a new method la valeur de n 3 moyenne des coordonnees du neve a trois dimensions peut etre estimee a partir de n 2 nombre moyen des mesures a deux dimensions et a partir d une fonction qui depend uniquement du rapport entre le rayon moyen de voisinage et de celui du grain de l echantillon

on the fundamental difference between coal rank and coal type abstract this article addresses the fundamental difference between coal rank and coal type while theoretically settled long ago as being different aspects of coal systems science the two concepts are still often confounded in recent years this has resulted in the publication of several works stating that coal type changes with coal rank coal type refers solely to coals depositional origin and the maceral mineral admixture resulting from that origin coal types typically fall in to two categories humic coals developed from peat and sapropelic coals developed from organic mud either type may be allocthonous or autochthonous and within types further refinement of depositional environment can be made coal rank refers to the changes in geochemistry and resultant changes in reflectance caused by increasing thermal maturity of the coal thus it provides an overprint of maturity on existing coal types with proper techniques such as use of crossed polars and etching maceral forms can be differentiated even at high ranks and the original coal type determined

a new method for predicting transport properties of polar firn with respect to gases on the pore space scale abstract in this study a powerful tool to investigate the permeabilities and effective diffusion coefficients of polar firn is presented using a combination of an experimental method for three dimensional pore structure reconstruction and two models to simulate advective and diffusive transports of gases through the pore space the reconstruction follows a semi automated digital analysis of serial surface sections the simulations are based on a three dimensional lattice boltzmann formulation they separately solve the navier stokes equation and the diffusive transport equations in a first application effective diffusion coefficients and permeabilities are calculated from firn samples of a core drilled during the north greenland traverse 1993 95 the estimated relationships of diffusivity and permeability to the open porosity are expressed by power law functions with exponents 2 1 and 3 4 respectively

geostatistical seismic amplitude versus angle inversion seismic inversion plays an important role in reservoir modelling and characterization due to its potential for assessing the spatial distribution of the subsurface petro elastic properties seismic ava inversion methodologies allow to retrieve p wave and s wave velocities and density individually allowing a better characterization of existing litho fluid facies we present an iterative geostatistical seismic ava inversion algorithm that inverts pre stack seismic data sorted by angle gather directly for density p wave and s wave velocity models the proposed iterative geostatistical inverse procedure is based on the use of stochastic sequential simulation and co simulation algorithms as the perturbation technique of the model parameter space and the use of a genetic algorithm as a global optimizer to make the simulated elastic models converge from iteration to iteration all the elastic models simulated during the iterative procedure honour the marginal prior distributions of p wave velocity s wave velocity and density estimated from the available well log data and the corresponding joint distributions between density versus p wave velocity and p wave versus s wave velocity we successfully tested and implemented the proposed inversion procedure on a pre stack synthetic dataset built from a real reservoir and on a real pre stack seismic dataset acquired over a deep water gas reservoir in both cases the results show a good convergence between real and synthetic seismic and reliable high resolution elastic subsurface earth models this article is protected by copyright all rights reserved

petrography and geochemistry of oligocene bituminous coal from the jiu valley petrosani basin southern carpathian mountains romania abstract belt samples of oligocene chattian bituminous coal from 10 underground mines located in the jiu valley hunedoara county petrosani basin romania have been examined and analyzed for proximate and ultimate analysis major minor and trace element chemistry organic petrography and vitrinite reflectance the mineral chemistry and mode of occurrence of trace elements also have been investigated using sem and electron microprobe techniques twenty coal beds occur in the jiu valley and most of the samples are from bed no 3 the most productive bed of the dilja uricani formation of oligocene age the petrosani basin oriented sw ne is 48 km long 10 km wide at the eastern part and 2 km wide at the western part the coal mines are distributed along the center of the valley generally following the jiu de vest river reflectance measurements indicate that the rank of the coals ranges from high volatile b to high volatile a bituminous overall rank decreases from the southwest to the northeast in bed no 3 r max varies from 0 75 in the northeast to 0 93 in the southwest although most oligocene coals in romania and adjacent countries are lignite in rank the jiu valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the alpine orogenic event the coals are all dominated by vitrinite resinite and funginite are important minor macerals in most of the coals pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest siderite occurs as nodules and masses within the macerals generally vitrinite dolomite and calcite occur as fracture fillings plant cell fillings and in other authigenic forms late stage fracture fillings are siderite dolomite calcite and ankerite in one instance two populations of siderite 35 and 45 wt feo plus ankerite fill a large fracture late stage pyrite framboid alteration is ni and cu bearing with ni rich pyrite hydrated ni fe sulfate chalcopyrite and rare pentlandite and clausthalite some of the mines sampled in 2001 have been closed as romania has undergone severe economic and environmental reforms in preparation for its 2007 entry into the european union eu romania s continued efforts to adapt to a market economy within the environmental and economic constraints of the eu make this collection of data valuable as the eventual fate of the other mines in jiu valley is unknown

geochemical petrographic and palynologic characteristics of two late middle pennsylvanian asturian coal to shale sequences in the eastern interior basin usa abstract two coal to shale sequences of late middle pennsylvanian asturian age from the southern portion of the eastern interior illinois basin usa were examined geochemically petrographically and palynologically the springfield coal was found to be moderately low in ash yield and high in total sulfur content petrographically the coal is high in vitrinite content and low in liptinite and inertinite palynologically the bed is co dominated by spores of arborescent lycopod and tree fern affinities the examination of closely spaced bench samples revealed vertical species variation within both of these plant groups lycospora micropapillata l orbicula both of which were produced by paralycopodites are most abundant in basal coal benches whereas lycospora granulata produced by lepidophloios is the dominant arborescent lycopod spore throughout the rest of the bed thymospora pseudothiessenii is the dominant tree fern spore throughout most of the coal with laevigatosporites globosus becoming dominant in the top most coal benches the herrin coal bed is also moderately low in ash yield and high in total sulfur content unlike the springfield coal it contains two distinct inorganic partings that have regional extent the herrin coal also has several coal benches with increased ash and sulfur that were not present in the springfield coal bed petrographically it is dominated by vitrinite with the partings and high ash coal benches containing more inertinite and liptinite palynologically the herrin coal is dominated by arborescent lycopod spores with subdominant tree fern spores as with the springfield coal lycospora micropapillata l orbicula are the dominant arborescent lycopod spores at the base of the coal with lycospora granulata dominating the rest of the bed granasporites medius which was produced by diaphorodendron and synchysidendron occurs more frequently in the herrin coal bed and are most abundant in and in proximity to the two inorganic partings tree fern spores are less abundant in the herrin coal and do not display any discernable vertical species variation collectively both the springfield and herrin coal beds are interpreted to have formed in extensive planar topogenous mires consistently saturated peat conditions throughout the development of both paleomires are indicated by the high vitrinite contents and prevalence of arborescent lycopods the deposition of widespread inorganic partings in the herrin coal represents significant events in peat accumulation with high ash coal benches representing smaller more local events both of the coals are overlain by black very organic rich avg toc 20 marine shales the turner mine shale which directly overlies the springfield coal has layers at the coal shale contact with fairly abundant vitrinite primarily in the form of vitrodetrinite near the base of the shale but the majority of the shale is dominated by the liptinite macerals bituminite lamalginite and amorphinite micrinite is a major organic component of the shale the anna shale which directly overlies the herrin coal is similar in overall maceral composition but contains less vitrinite and more solid bitumen and micrinite trace element ratios ni co v cr v v ni indicative of paleoredox conditions indicate that both shales were deposited under mainly dysoxic to suboxic anoxic conditions the shales are interpreted to represent a progressively rising water table caused by an increase in eustatic sea levels vitrinite reflectance values in the shales are lower than corresponding values measured from the coal indicating some degree of vitrinite suppression occurring in the turner mine and anna shales

metamorphism of stratified firn at dome fuji antarctica a mechanism for local insolation modulation of gas transport conditions during bubble close off 1 the evolution of the structure of a 112 59 m long firn core recovered at dome fuji east antarctica was investigated in order to improve understanding of firn densification and bubble formation processes which are important for interpreting local insolation proxies used for astronomical dating of deep ice cores using selected samples we measured physical properties including 1 the relative dielectric permittivities in both the vertical and horizontal planes 2 the bulk density at a resolution of millimeters 3 the three dimensional geometric structure of pore space and 4 crystal orientation fabrics we found that the firn at dome fuji contains horizontal strata with thicknesses of several centimeters near the surface of the ice sheet these strata are characterized by contrasting bulk density earlier field studies suggest that summer insolation causes densification of surface firn down to 30 m density maxima exhibited a clear positive correlation with the strength of structural anisotropy and c axis clustering around the vertical in contrast the correlation is negative in deeper firn confirming previous findings that initially less dense firn became denser than initially dense firn in addition numerous examples of textures indicating that deformation preferentially occurred in weaker layers were found moreover the initially dense firn layers were more permeable for air near the bottom of firn we propose a model linking firn properties with conditions for the gas transport processes near the bottom of firn the model explains how stronger insolation can lead to bulk ice with a lower o2 n2 ratio and smaller total gas content

notes on the origin of inertinite macerals in coals funginite associations with cutinite and suberinite abstract the association of fungus with plant leaves and roots is ubiquitous while many of these occurrences are considered to be pathogenic mycorrhizzal fungal associations with roots are essential for plant growth despite the common knowledge of such relationships in plant science with a few exceptions the fungus leaf root stem association as the macerals funginite cutinite and suberinite in coals has not been extensively studied in this work examples of funginite associations with cutinite and suberinite are discussed

comparison of elastic moduli from seismic diving wave and ice core microstructure analysis in antarctic polar firn we compared elastic moduli in polar firn derived from diving wave refraction seismic velocity analysis firn core density measurements and microstructure modelling based on firn core data the seismic data were obtained with a small electrodynamic vibrator source near kohnen station east antarctica the analysis of diving waves resulted in velocity depth profiles for different wave types p sh and sv waves dynamic elastic moduli of firn were derived by combining p and s wave velocities and densities obtained from firn core measurements the structural finite element method fem was used to calculate the components of the elastic tensor from firn microstructure derived from x ray tomography of firn core samples at depths of 10 42 71 and 99 m providing static elastic moduli shear and bulk moduli range from 0 39 to 2 42 gpa and 0 68 to 2 42 gpa respectively the elastic moduli from seismic observations and the structural fem agree within 8 5 for the deepest achieved values at a depth of 71 m and are within the uncertainty range our observations demonstrate that the elastic moduli of the firn can be consistently obtained from two independent methods which are based on dynamic seismic and static tomography and fem observations respectively for deeper layers in the firn below 10 m depth

textures and fabrics in the grip ice core a comprehensive study of textures and fabrics has been carried out on the greenland ice core project grip ice core crystal sizes and c axis orientations have been measured on thin sections with conventional techniques yielding new information on the growth rotation and recrystallization of ice crystals in the greenland ice sheet normal grain growth is found to persist to a depth of 700 m in the core where the onset of polygonization due to increasing strain prevents a further increase in grain size in the holocene ice smaller crystals are observed in the wisconsin ice larger crystals are found in the eemian ice and the crystal size is found to vary with climatic parameters in these periods this dependence which probably results from variable impurity content in the ice persists to a depth of 2930 m coarse grained ice probably resulting from rapid growth of crystals at comparatively high temperatures is found in the lowest 100 m of the core the data on c axis orientations reveal a steady evolution of the fabric from random near the surface to a strong single maximum in the lower part of the ice sheet a significant strengthening is not observed at the holocene wisconsin transition the fabric development indicates that vertical compression at the ice divide is the main mode of deformation down to a depth of 2850 m the evolution toward a single maximum fabric hardens the ice against vertical compression but softens it against simple shear evidence of simple shear deformation is clearly observed between 2850 m and 2950 m depth stretched fabrics in coarse grained ice in the lowest 100 m could be due to tensional stresses this ice is unlikely to be undergoing any significant horizontal deformation at the present time

short note on petrographically differentiating the anatomical characteristics of saprotrophied and carbonised inertinite group macerals the use of inertinite macerals as palaeoenvironmental and palaeoclimatic indicators is reliant on understanding their origin criteria to distinguish between carbonisation and pyrolysis or saprotrophy resulting from fungal degradation are not always clear without the presence of primary particles in coal such as fungal sclerota hyphae char and fly ash the origin of inertinites is difficult to distinguish this short study provides an insight into basic anatomical characteristics which differentiate saprotrophied and carbonised inertinite group macerals modern plant matter and permian phyterals are compared petrographically to observe changes in the macerals at a cellular level saprotrophic effects include thickening of the cell wall and cellular damage delignification of the cell wall and cross ray piths and the irregular oxidation radiating from xylem tissues these characteristics are not observed in carbonised inertinites that show enlarged ray cells and the shrinking and homogenisation of cell walls the simple differentiation between these characteristics in inertinites can greatly affect the palaeoenvironmental interpretations linked to the presence of inertinites in coal

petrology mineralogy and geochemistry of the ge rich coal from the wulantuga ge ore deposit inner mongolia china new data and genetic implications abstract the early cretaceous wulantuga high ge coal deposit in inner mongolia is one of the major coal hosted ge deposits in china this paper reports new data on the petrological mineralogical and geochemical compositions of 13 bench samples of the high ge no 6 coal from the wulantuga deposit and provides new insight into the origin and modes of occurrence of the minerals and elements present the no 6 coal has a low rank ro max 0 45 and is a low ash coal 8 77 the total content of inertinite 52 5 vol on average in most coal benches is higher than that of huminite 46 8 vol on average the dominant huminite maceral is textinite averages 43 9 and the dominant inertinite macerals are mainly fusinite averages 33 and semifusinite 12 5 along with trace portions of intertodetrinite secretinite funginite and macrinite fungus seen as the maceral funginite played a role in the development of degraded maceral forms in the wulantuga coals funginite is present in samples examined in this study but is not easily extracted during palynological studies recovered fungal taxa are saprophytes indicating woody decomposition prior to incorporation in the mire palynology revealed a sparse flora that is consistent with the early cretaceous age minerals in the coal include quartz kaolinite illite and or illite smectite gypsum pyrite and traces of rutile and anatase a varying proportion of bassanite was observed in the low temperature ashes ltas bassanite in the ltas was derived both from the dehydration of gypsum in the raw coals and from the interaction between organically associated ca and s during the low temperature ashing in addition to a proportion of detrital quartz fine grained and cell filling quartz of authigenic origin is also present pyrite is of syngenetic origin and derived from sulfate rich hydrothermal fluids compared to common chinese and world low rank coals the no 6 coal is enriched in be 25 7 g g f 336 g g ge 274 g g as 499 g g sb 240 g g cs 5 29 g g w 115 g g hg 3 165 g g and tl 3 15 g g germanium in the coal is organically associated and its enrichment is attributed to hydrothermal fluids from the adjacent granitoids beryllium is probably associated with ca and mn bearing carbonate minerals and to a lesser extent with clay minerals rather than with organic matter fluorine largely occurs in clay minerals kaolinite and illite the elevated concentrations of tl hg as and sb are mainly distributed in pyrite and were derived from the same hydrothermal source the high w in the coal occurs in both the organic matter and the authigenic quartz illite is the major carrier of cs in the coal the accumulation of rare earth elements ree in the coals had a polygenetic and multistage nature including two syngenetic stages early hydrothermal and terrigenous and one diagenetic late hydrothermal stage the ree distribution patterns of the early hydrothermal and terrigenous stages were characterized by the enrichment of medium ree m type ree and light ree l type ree respectively a h type ree distribution pattern hree enrichment occurred in the late diagenetic hydrothermal stage the high ge wulantuga coals are also abnormally enriched in precious metals gold pt and pd in the coals calculated from their concentrations in the ltas are 3 5 25 8

notes on the origin of inertinite macerals in coals observations on the importance of fungi in the origin of macrinite macrinite is a generally rare inertinite maceral often incorporating remnants and fragments of other macerals including vitrinite liptinite and other inertinite the associated inertinites include multiple forms of funginite funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite together with the highly degraded macrinite the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat in any case the origin of some macrinite is potentially distinct from that of inertinite generated by fire

macrinite forms in pennsylvanian coals abstract fungi are not as evident in pennsylvanian coals as in younger mesozoic or cenozoic coals however macerals formed through the interaction of fungi with woody and herbaceous precursors do occur one example of this is in some forms of the maceral macrinite this study analyzes macrinite forms from geographically distinct pennsylvanian coals the macrinite observed in this study is characterized by the presence of inclusions of other detrital macerals indicative of ingestion and excretion similar to that documented in macrinite of younger coals this suggests that while not all ecologic niches in the pennsylvanian were filled in the same manner as in younger settings similar processes implying similar types of interactions between fungi bacteria and fauna were producing similar products

enclosure of air during metamorphosis of dry firn to ice if cold firn has reached a density of about 0 55 mg m 3 further densificaron occurs by a sintering process which increases the contact surface between the firn grains the pore volume is decreasing continuously but the firn remains permeable to air up to a density of 0 82 mg m 3 at about this density the remaining air in the pore volume is closed off in isolated bubbles we are interested in the age and the age distribution of the air enclosed in bubbles relative to the age of the surrounding ice and are investigating the development of the pore volume in firn a newly constructed measuring device allows the field measurement of the amount of air which is already enclosed in bubbles of firn samples measurements have been made during summer 1983 in greenland and during winter 1983 84 at the south pole the results are discussed and compared with results obtained with a simplified statistical sintering model using some results of percolation theory

the depth of penetration in antarctic firn at 10 ghz measurements taken by an x band pulse radar system in east antarctica in 1987 were analyzed to determine the depth of penetration of radar energy in polar firn a minimum estimate of the penetration depth at 10 ghz for the cold and dry polar plateau region is approximately 4 7 m spatial variations in the amount of signal penetration were observed and are related to latitude surface elevation and mean annual temperature the amount of signal penetration and its spatial variation are important factors that should be considered when processing datasets from microwave remote sensing systems that operate in the polar regions

snow stratigraphic heterogeneity within ground based passive microwave radiometer footprints implications for emission modeling two dimensional measurements of snowpack properties stratigraphic layering density grain size and temperature were used as inputs to the multilayer helsinki university of technology hut microwave emission model at a centimeter scale horizontal resolution across a 4 5 m transect of ground based passive microwave radiometer footprints near churchill manitoba canada snowpack stratigraphy was complex between six and eight layers with only three layers extending continuously throughout the length of the transect distributions of one dimensional simulations accurately representing complex stratigraphic layering were evaluated using measured brightness temperatures large biases 36 to 68 k between simulated and measured brightness temperatures were minimized 0 5 to 0 6 k within measurement accuracy through application of grain scaling factors 2 6 to 5 3 at different combinations of frequencies polarizations and model extinction coefficients grain scaling factors compensated for uncertainty relating optical specific surface area to hut effective grain size inputs and quantified relative differences in scattering and absorption properties of various extinction coefficients the hut model required accurate representation of ice lenses particularly at horizontal polarization and large grain scaling factors highlighted the need to consider microstructure beyond the size of individual grains as variability of extinction coefficients was strongly influenced by the proportion of large hoar grains in a vertical profile it is important to consider simulations from distributions of one dimensional profiles rather than single profiles especially in sub arctic snowpacks where stratigraphic variability can be high model sensitivity experiments suggested that the level of error in field measurements and the new methodological framework used to apply them in a snow emission model were satisfactory layer amalgamation showed that a three layer representation of snowpack stratigraphy reduced the bias of a one layer representation by about 50

dunkard group coal beds palynology coal petrography and geochemistry abstract coal beds that occur in the dunkard group are typically thin avg 0 3 m and are high in ash yield avg 27 8 and total sulfur content avg 5 1 petrographically dunkard coals are high in vitrinite avg 83 1 mmf with correspondingly low to moderate amounts of liptinite avg 2 1 mmf and inertinite avg 13 8 mmf palynologically dunkard coal beds are all dominated by tree fern spore taxa avg 96 3 especially punctatisporites minutus avg 82 8 calamite spores are the second most abundant plant group avg 2 4 with others lycopods small ferns cordaites and other gymnosperms having very minor representation overall the coal palynofloras are strongly dominated by lowland plants ferns and calamites with only rare occurrences of bisaccate striate conifer pollen coal beds of the underlying monongahela group pittsburgh redstone sewickley and waynesburg are thicker avg 1 6 m and are lower in ash avg 13 4 and sulfur avg 3 3 than their dunkard counterparts petrographically monongahela group coals are very similar to dunkard group coals when compared on a mineral matter free basis coal beds that occur in both groups are strongly dominated by vitrinite macerals monongahela group coals are also palynologically very similar to dunkard group coals with tree fern spore taxa dominating a coal bed of early permian age from west central texas is also similar petrographically and palynologically to dunkard and monongahela coals being vitrinite and tree fern spore dominant the almost complete lack of coniferous pollen in dunkard coals led earlier workers to conclude that the dunkard was entirely late pennsylvanian and not permian in age however it is now known that late pennsylvania lowland floras persisted into the dunkard especially during wet intervals as earlier interpretations were based primarily on spore and pollen floras from coal beds the lack of conifer pollen in dunkard coals is probably the result of a sampling bias because of this ecological bias coal palynology is a poor proxy for age dating dunkard group coals collectively dunkard swamps were all planar and topogenous their formation being controlled by topography and moisture availability a progressive decrease in wet intervals both in terms of frequency and duration during the dunkard was the major control on peat accumulation and preservation collectively moisture limitation appears to be the principle factor that controlled the formation of dunkard group coals

an investigation of wulantuga coal cretaceous inner mongolia macerals paleopathology of faunal and fungal invasions into wood and the recognizable clues for their activity coal macerals are the product of a complex series of decompositional and preservational pathways from living woody and herbaceous tissues to the variety of forms seen in coal the cretaceous wulantuga coal inner mongolia china offers an opportunity to observe a number of maceral forms resulting from these disparate pathways assemblages of coprolites within fusinite strongly suggest an origin related to arthropod ingestion and consequent in situ emplacement of the macrinitic coprolites within the damaged wood structure followed by combustion of the whole to achieve the observed reflectance

microstructural evolution of fine grained layers through the firn column at summit greenland we present a microstructural characterization of fine grained layers from the top 90 m of firn from summit greenland performed using a combination of scanning electron microscopy techniques including secondary electron imaging energy dispersive spectroscopy and electron backscattered patterns and x ray microcomputed tomography the impurities in the firn both soluble impurities and dust particles were found largely in the grain interiors both c and a axis pole figures do not show strong evidence of a preferred orientation of the grains even at the bottom of the firn column the firn structure became increasingly anisotropic with vertical alignment in the top 3 m probably due to vapor transport associated with dry snow metamorphism the anisotropy decreases below this level until at 50 m the average firn structure is close to isotropic in the near surface the level of anisotropy is weaker than at hercules dome antarctica confirming that differences in accumulation rates and temperatures leave enduring evidence in the structure of the firn the fraction of closed off pores is relatively low until 65 m below that it rises through the end of our sampling at 90 m our microstructure measurements on the microscale are consistent with in situ firn air sampling measurements on a decimeter scale both indicating the existence of the lock in zone starting near 69 m depth and pore close off at 81 m at this site

microstructure dependent densification of polar firn derived from x ray microtomography the densification of dry polar snow and firn results in a continuous increase of density with depth accompanied by significant density fluctuations within seasonal layers density measurements of high spatial resolution reveal a persistent minimum of density fluctuations in the vicinity of the snow firn transition 0 55 0 65 g cm 3 in firn core records in this study we give an explanation for the fluctuation minimum by applying a new method of x ray microtomography to obtain three dimensional 3 d structural data of a greenland firn core at 13 different depths between 10 and 78 m a set of 16 samples of 40 cm total length for each depth interval was measured a reconstructed firn segment of 40 cm covers 1 2 years of snow accumulation using digital image analysis techniques different structural parameters are estimated including 3 d pore and particle sizes and specific surface areas it is shown that the densification rates of snow and firn layers consisting of coarse particles are much higher than those consisting of fine particles within the same depth interval this causes a density crossing of fine and coarse grained layers with a minimum of density variations at the crossover point this crossing over implies that formerly dense layers in the seasonal density signal are not of the same origin as dense layers in the deeper part of the firn column and that the seasonal density signal will totally change shape with depth it is speculated that in coarse and fine grained firn the dominant mechanism of densification acts over different regimes of density

observing and modeling the influence of layering on bubble trapping in polar firn interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn much work has been done to understand the processes affecting air transport in the open pores of the firn but a paucity of data from air trapped in bubbles in the firn ice transition region has limited the ability to constrain the effect of bubble closure processes here we present high resolution measurements of firn density methane concentrations nitrogen isotopes and total air content that show layering in the firn ice transition region at the west antarctic ice sheet wais divide ice core site using the notion that bubble trapping is a stochastic process we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach we include the process of bubble trapping into an open porosity firn air transport model and obtain a good fit to the firn core data we find that layering broadens the depth range over which bubbles are trapped widens the modeled gas age distribution of air in closed bubbles reduces the mean gas age of air in closed bubbles and introduces stratigraphic irregularities in the gas age scale that have a peak to peak variability of 10 years at wais divide for a more complete understanding of gas occlusion and its impact on ice core records we suggest that this experiment be repeated at sites climatically different from wais divide for example on the east antarctic plateau

grain growth in polar ice i theory many observations regarding grain growth in ice sheets are glaciologically interesting but imperfectly understood here we develop the theory of grain growth in ice that is not deforming rapidly and in the succeeding paper we use this theory to explain observations from glacial ice in the absence of significant strain energy the driving force for grain growth arises from grain boundary curvature grain growth is slowed by the interaction of grain boundaries with extrinsic materials microparticles bubbles and dissolved impurities if the driving force for growth is not large enough to cause boundaries to separate from an extrinsic material then the grain boundary velocity is determined by the velocity characteristic of the extrinsic material low velocity regime if the driving force is large enough to cause separation then boundaries migrate more rapidly than the extrinsic material high velocity regime but the net driving force is reduced through transient pinning by the extrinsic material polar ice is typically in the low velocity regime relative to dissolved impurities and the high velocity regime relative to microparticles and bubbles cross sectional area of grains is predicted to increase linearly with time under most but not all circumstances

densification of layered firn of the ice sheet at neem greenland densification of firn at the north greenland eemian ice drilling neem camp is investigated using density surrogates dielectric permittivities v and h at microwave frequencies with electrical fields in the vertical and horizontal planes respectively dielectric anisotropy v h is then examined as a surrogate for the anisotropic geometry of firn its size fluctuations and mutual correlations are investigated in samples taken at depths from the surface to 90m the initial of 0 06appears within the uppermost 0 2 m after that decreases rapidly until 21 26 m depth below this decreases slowly layers with more ions of fluorine chlorine and some cations deposited between the autumn and the subsequent summer deform preferentially during all these stages this layered deformation is explained partly by the textural effects initially formed by the seasonal variation of metamorphism and partly by ions such as fluorine chlorine and ammonium which are known to modulate dislocation movement in the ice crystal lattice insolation sensitive microstructure appears to be preserved all the way to the pore close off within layers of the summer to autumn metamorphism like previous authors we hypothesize that calcium is not the active agent in the reported deformation calcium correlations

a pressure sintering model for the densification of polar firn and glacier ice on presente les predictions de la theorie de frittage pression pour la glace pure et on les compare avec les mesures d indlandsis au groenland et en antarctique

petrophysical seismic inversion conditioned to well log data methods and application to a gas reservoir hydrocarbon reservoirs are characterized by seismic welllog and petrophysical information which is dissimilar in spatial distribution scale and relationship to reservoir properties we combine this diverse information in a unified inverse problem formulation using a multiproperty multiscale model linking properties statistically by petrophysical relationships and conditioningthemtowell logdata twoapproacheshelpus 1markov chainmontecarlosampling whichgeneratesmanyreservoir realizationsforestimatingmediumpropertiesandposteriormarginalprobabilities and2optimizationwithaleast squaresiterativetechniquetoobtainthemostprobablemodelconfiguration our petrophysical model applied to near vertical anglestacked seismicdataandwell logdatafromagasreservoir includesadeterministic component based on a combination of wyllie and wood relationships calibrated with the well log data and a random component based on the statistical characterization of the deviations of well log data from the petrophysical transform at the petrophysical level the effects of porosity and saturation on acoustic impedance are coupled conditioning the inversion to well log data helps resolve this ambiguity the combination of well logs petrophysics and seismic inversion builds on the correspondingstrengthsofeachtypeofinformation jointlyimproving 1 cross resolution of reservoir properties 2 vertical resolution of property fields 3 compliance to the smooth trend of property fields and 4 agreement with well log data at well positions

seismic inversion for reservoir properties combining statistical rock physics and geostatistics a review there are various approaches for quantitative estimation of reservoir properties from seismic inversion a general bayesian formulation for the inverse problem can be implemented in two different work flows in the sequential approach first seismic data are inverted deterministically or stochastically into elastic properties then rock physics models transform those elastic properties to the reservoir property of interest the joint or simultaneous work flow accounts for the elastic parameters and the reservoir properties often in a bayesian formulation guaranteeing consistency between the elastic and reservoir properties rock physics plays the important role of linking elastic parameters such as impedances and velocities to reservoir properties of interest such as lithologies porosity and pore fluids geostatistical methods help add constraints of spatial correlation conditioning to different kinds of data and incorporating subseismic scales of heterogeneities

in situ measurements of antarctic snow compaction compared with predictions of models 1 we describe in situ measurements of the compaction of antarctic snow at three different sites in antarctica the rate of compaction was measured hourly over various depth intervals for up to two years these measurements show that compaction at each of the sites occurs through slow viscous deformation of the snowpack with no significant contribution from sudden collapse of weak layers the measured rates of compaction at the coldest site exhibit a strong seasonality consistent with a temperature dependent sintering mechanism having activation energy of 70 kj mol 1 at the two warmer sites activation energies of 80 and 120 kj mol 1 provide slightly better agreement with the observations published models of snow compaction underestimate the temperature sensitivity a good match to our observations is provided by a semi empirical model based on rate equations for lattice diffusion nabarro herring creep of material around pores combined with normal grain growth this model also provides a theoretical basis for a widely used empirical model of snow compaction the rate coefficient for lattice diffusion inferred from our measurements is considerably higher than published values however and other creep mechanisms cannot be ruled out

polar ice structure and the integrity of ice core paleoclimate records abstract polar ice is a unique archive of the climatic conditions in the past however ice sheets flow and this flow may affect the integrity of paleoclimate records a useful method to analyze the effect of ice flow upon climate records is the combination of microstructure mapping with ice core line scanning microstructure and stratigraphy have been mapped along the entire epica dml ice core with this combined method on the macroscale the stratigraphy seems perfectly preserved down to ca 1700 m depth mis4 below which minor undulations start to develop layers inclined up to 15 and millimeter scale z folds are observed below 2050 m depth notwithstanding the epica dml climate record appears not seriously disturbed down to ca 2400 m depth which marks the climatic transition from the last interglacial mis5e to the mis6 glacial period below this depth the synchronization with the epica dome c record is lost and stratigraphic disturbances appear up to the meter scale on the microscopic scale we observe dynamic recrystallization already in deep firn leading to substantial microstructural changes prior to bubble close off the concentration of visible micro inclusions in the holocene part of the core seems to increase with depth which could possibly indicate post depositional formation of salts in glacial period ice the concentration of visible micro inclusions in certain layers is so high that these strata appear as light scattering bands often called cloudy bands another interesting stratigraphic feature is what we call bubble free bands viz millimeter thick strata deprived of bubbles and rich in clathrate hydrates which are found within the bubble hydrate transition zone 800 1200 m depth and are probably caused by anomalously fast clathration while there is hardly any interaction between visible micro inclusions and grain boundaries down to 2500 m depth in the deeper ice warmer than 10 c many grain boundaries seem to harvest micro inclusions here we discuss these observations and their relevance for the interpretation of climate records

the connectivity of crystallite agglomerates in low density firn at kohnen station dronning maud land antarctica in this study the three dimensional 3 d microstructure of polar firn is investigated by means of x ray microfocus computer tomography mct basic topological properties including the euler and coordination numbers are derived from the reconstructed 3 d volume images it is shown that sample volumes of about 4 cm 3 are representative for polar firn in terms of their connectivity the connectivity function defined as the change of euler number with structure size is calculated via image processing routines it is used to split the ice phase at small bridges into single crystallite agglomerates the bond size distributions and the mean size of the agglomerates are estimated all mct measurements were carried out on the uppermost 9 m of a shallow firn core b35 drilled during the 2005 06 field campaign at kohnen station dronning maud land dml antarctica the results are compared with estimates from classical two dimensional 2 d surface section observations the 3 d approach confirms the linear relationship between coordination number and density which hitherto has only been derived from 2 d observations layers of buried snow dunes show a stronger connectivity than layers of moderate crystal size and density the formation of agglomerates made of crystallites is a common feature of polar firn in dml it is proposed that the growth of agglomerates leads to reduced critical densities for the transition between the densification regime of grain boundary sliding and plastic deformation

theory of metamorphism of dry snow the growth of ice particles in dry seasonal snow is caused by vapor diffusion among particles due to temperature gradients imposed on the snow cover the diffusion is calculated by using the potential field solutions for electrostatically charged particles the stereography of snow is represented by using a log normal distribution function for a geometrical enhancement factor defined here reasonable crystal growth rates and supersaturations are found the transition between the growth of highly faceted crystals and the growth of highly rounded crystals is determined by the critical supersaturation for the onset of dislocation aided growth thermal convection and the continuous movement of vapor around the particles due to the imposed temperature gradient are accommodated in the theory although both have little effect relative to the interparticle diffusion the growth of a layer of faceted crystals just below semi permeable crusts is explained by showing that crusts can cause the local supersaturation to exceed the critical value faceted crystals are shown to grow most rapidly in the lower warmer portions of the snow cover because of temperature effects on growth rate

the impact of accumulation rate on anisotropy and air permeability of polar firn at a high accumulation site the first three dimensional properties of polar firn obtained by x ray microtomography are used to study the microstructure of snow on a 15 m deep firn core from west antarctica the snow is found to undergo coarsening down to approximately 2 5 m depth before grain growth and densification become the prevalent mechanisms of microstructure change in contrast to previous assumptions distinct anisotropy of the ice and pore geometry is observed throughout the profile with a maximum at 2 5 m depth the air permeability and the degree of anisotropy vary with depth and can be linked to short term changes in accumulation rate via the residence time for which a certain snow layer stays in the uppermost 2 5 m patterns of the degree of anisotropy and air permeability of buried polar firn are relative indicators of past accumulation rates

polar firn densification and grain growth a 50 m firn core from dome c east antarctica was found to consist of coarse firn which comprised 90 to 95 of the core and fine firn coarse firn was characterized by large crystals with a vertical shape orientation near the surface connected to nearest neighbors by relatively large necks in a structure different from closest packing fine firn was of higher density and consisted of smaller more spherical crystals connected by relatively narrow necks in a more nearly closest packed configuration higher surface free energy in fine firn causes crystals and necks to grow more rapidly than in coarse firn however we find that coarse firn densifies more rapidly with time contrary to the predictions of unconfined sintering models load driven densification due to a power law creep mechanism is found to account for the larger coarse firn densification rate however if the exponent in the power law exceeds one then densification rates are predicted to increase with depth due to increasing load contrary to observed behavior we speculate that different mechanisms may control the densification process in fine and coarse firn

funginite resinite associations in coal abstract petrographic examination of a series of indian tertiary age coal seams some with 38 resinite mineral free basis showed that several had associations of funginite in resinite there are three primary mechanisms for incorporation of fungus into resinite 1 as an accidental inclusion for example as a fungal infection on an insect encapsulated in resin 2 infestation of fungus into tree whether into a wound or other point of entry with encapsulation by resin as a defense mechanism by the tree alternatively fungal hyphae could also be growing from another portion of the tree that is already infected and 3 resinicolous fungus using the resin as a food source in the coal samples examined while incidental fungal inclusion on invading insects cannot be eliminated we have seen no direct evidence for insects both encapsulation of invading fungus by resin and resinicolous relationships are among the associations observed

on the impact of impurities on the densification of polar firn abstract understanding polar firn densification is crucial for reconstructing the age of greenhouse gas concentrations extracted from ice cores and for the interpretation of air in ice as a dating tool or as a climate proxy firn densification is generally modeled as a steady burial and sintering process of defined layers where the structure of the layering is maintained along the whole firn and ice column however available high resolution density data as well as firn air samples question this picture and point to a lack of understanding of firn densification based on analysis of high resolution density and calcium concentration records from antarctic and greenland ice cores we show for the first time that also impurities may have a significant impact on the densification analysis of firn cores shows a correlation between density and the calcium ion ca concentration and this correlation increases with depth the existence of this relationship is independent of the local climatic conditions at the core sites analyzed the strong positive correlation between the density and the logarithm of ca concentration indicates that impurities induce softening and lead to faster densification over a wide range of concentrations in one core the impurity effect manifests itself so strongly that the density develops a seasonal cycle closely following the seasonal cycle of ca our results clearly show that the structure of the firn layering changes with depth and suggest that the increased variability in density observed in deep firn recently described as a universal feature of polar firn may arise from the influence of ca and or other impurities the impurity effect is likely to have direct implications on our understanding of glacial firn densification and on glacial gas age estimates

fungal origin of oxidised plant material in the palangkaraya peat deposit kalimantan tengah indonesia implications for inertinite formation in coal abstract the top 1 0 1 5 m of the 6 m thick palangkaraya peat deposit in indonesia is decaying aerobically and contains up to 22 oxidised plant material i e inertinite in contrast intervals below the level of water table fluctuation contain less than 5 oxidised material analysis of fungal remains in the peat show there is a coincident increase in total aggregate hyphal length a measure of fungal activity with the proportion of oxidised plant constituents macroscopically the top of the peat which contains the greatest proportion of oxidised material is black lacks wood fragments and would be classed as a sapric or sapric hemic peat oxidised material in the peat is predominantly epidermal cell walls of primary roots these cell walls are abnormally thickened and display a distinctive dentate structure in cross section the texture of the cell walls are either laminated or granular and often contains intercellular nodules these features together with the absence of charcoal layers in the peat suggest that oxidised constituents were derived from fungal alteration furthermore the coincident increase in fungal hyphal length with the proportion of oxidised material may suggest a causal link based on texture morphology and size the same types of oxidised plant material found in the palangkaraya peat deposit have been identified in coal beds of tertiary age from indonesia new zealand and the u s a this indicates similar fungal alteration occurred in the past and may account for some of the oxidised constituents found in coal if the palangkaraya mire is used as a model fungal alteration zones may be recognised in coals as relatively thick 0 5 2 0 m laterally extensive macroscopically dull coal

advanced microstructural characterization of four east antarctic firn ice cores the microstructures and microchemistry of four us international trans antarctic scientific expedition ice cores were examined at three depths 30 60 90m each using scanning electron microscopy including electron backscattered patterns and energy dispersive spectroscopy eds in order to assess the relationship between chemical and physical properties the physical characteristics grain size porosity density internal surface volume and crystallographic orientation at the four sites were inhomogeneous as expected on the basis of differences in the moisture content of deposited snow and the accumulation rate at their respective locations evidence of shallow subgrain boundary formation and trends in internal surface volume having implications for the study of firn densification and ice sheet modeling were also found chemical characterization revealed that site specific variations in particulate concentration and source could accurately be determined using eds analysis it was also found that the combination of elements predominant within the sample controls the morphology and microstructural location of the impurities

ice shelf structure derived from dispersion curve analysis of ambient seismic noise ross ice shelf antarctica author posting the author s 2016 this article is posted here by permission of the royal astronomical society for personal use not for redistribution the definitive version was published in geophysical journal international 205 2016 785 795 doi 10 1093 gji ggw036

antarctic firn compaction rates from repeat track airborne radar data ii firn model evaluation the thickness and density of the antarctic firn layer vary considerably in time and space thereby contributing to ice sheet volume and mass changes distinguishing between these mass and volume changes is important for ice sheet mass balance studies evolution of firn layer depth and density is often modeled because direct measurements are scarce here we directly compare modeled firn compaction rates with observed rates obtained from repeat track airborne radar data over a 2 year interval 2009 11 in west antarctica spatially the observed compaction rates exhibit significant variability but when averaged to scales comparable to the model resolution 20 50 km the measurements and model results qualitatively agree a colder and drier period preceding the 2009 survey led to lower compaction rates during the 2009 10 interval when compared to 2010 11 which is partly captured by the firn model spatially higher compaction rates are observed and modeled in warmer regions with higher accumulation

geochemistry and petrology of selected coal samples from sumatra kalimantan sulawesi and papua indonesia abstract indonesia has become the world s largest exporter of thermal coal and is a major supplier to the asian coal market particularly as the people s republic of china is now 2007 and perhaps may remain a net importer of coal indonesia has had a long history of coal production mainly in sumatra and kalimantan but only in the last two decades have government and commercial forces resulted in a remarkable coal boom a recent assessment of indonesian coal bed methane cbm potential has motivated active cbm exploration most of the coal is paleogene and neogene low to moderate rank and has low ash yield and sulfur generally

macrinite and funginite forms in cretaceous menefee formation anthracite cerrillos coalfield new mexico abstract inertinite macerals in the anthracite rank campanian menefee formation coal from the cerrillos coalfield santa fe county new mexico show a range of forms consistent with forms found in lower rank mesozoic and younger coals in particular funginite is recognized in these anthracites as is macrinite and fusinite formed following microbial degradation the macrinite in the menefee coal has forms that are consistent with fungal and or bacterial degradation of wood followed by the ingestion of the latter material by insects or other animals the regurgitation or excretion of the partially digested material and the coprophagous recycling of the latter product

grain growth in polar ice ii application grain growth observed in polar ice that is not deforming rapidly can be accounted for if concentrations and distributions of extrinsic materials microparticles bubbles and dissolved impurities are characterized fully dissolved impurities segregate to grain boundaries and slow grain growth in all cold glacial ice the high concentration of soluble impurities in wisconsinan ice from the dome c antarctica ice core and perhaps other ice cores probably causes the small grain sizes observed in that ice microparticles have little effect on grain growth in ordinary ice in ice layers that appear dirty owing to concentrations of volcanic tephra such as in the byrd station antarctica ice core or of morainal material micro particles reduce grain growth rates significantly the relatively high vapor pressure of ice allows rapid growth and high mobility of intergranular necks so grain growth in firn is limited by boundary migration rather than by neck growth bubbles formed by pore close off at the firn ice transition are less mobile than grain boundaries causing bubble boundary separation whenever geometric constraints are satisfied however such separation reduces grain growth rates by only about 10 the observed linear increase of grain area with time is thus predicted by theory but the growth rate depends on soluble impurity concentrations as well as on temperature

imaging of firn and bubbly ice in coaxial reflected light a new technique for the characterization of these porous media a new technique for characterizing the structure of firn and bubbly ice is presented this technique based on observation of etched sublimation surfaces in coax ial reflected light enables one to see simultaneously the pore network of the firn or bubbles in the ice and the crystal boundaries at the same time the main stages of image proces sing used to transform the initial photographs into clean binary images are described

energy based binary segmentation of snow microtomographic images x ray microtomography has become an essential tool for investigating the mechanical and physical properties of snow which are tied to its microstructure to allow a quantitative characterization of the microstructure the grayscale x ray attenuation coefficient image has to be segmented into a binary ice pore image this step called binary segmentation is crucial and affects all subsequent analysis and modeling common segmentation methods are based on thresholding in practice these methods present some drawbacks and often require time consuming manual post processing here we present a binary segmentation algorithm based on the minimization of a segmentation energy this energy is composed of a data fidelity term and a regularization term penalizing large interface area which is of particular interest for snow where sintering naturally tends to reduce the surface energy the accuracy of the method is demonstrated on a synthetic image the method is then successfully applied on microtomographic images of snow and compared to the threshold based segmentation the main advantage of the presented approach is that it benefits from local spatial information moreover the effective resolution of the segmented image is clearly defined and can be chosen a priori

non gaussian gas hydrate grade simulation at the mallik site mackenzie delta canada abstract for the past decades gas hydrate reservoirs have beneficiated from an increasing attention in the academic and industrial worlds as a result there is a growing need to develop specific and comprehensive gas hydrate reservoir characterization methods this study explores the use of a stochastic bayesian algorithm to integrate well logs and 3d acoustic impedance in order to estimate gas hydrate grades product of saturation and total porosity over a representative volume of the mallik gas hydrate field located in the mackenzie delta northwest territories of canada first collocated log data from boreholes mallik 5l 38 and 2l 38 are used to estimate the statistical relationship between acoustic impedance and gas hydrate grades second conventional stochastic bayesian simulation is applied to generate multiple gas hydrate grade 3d fields integrating log data and lateral variability of 3d acoustic impedance these equiprobable scenarios permit to quantify the uncertainty over the estimation and identify zones where this uncertainty is greater contrary to conventional stochastic reservoir modeling workflows the proposed method allows integrating non gaussian and non linear distributions this permits to handle bimodal distributions without using complex stochastic transforms the results present gas hydrate grade values that are in accordance with well log data the relatively low standard deviation calculated at each pixel using all realizations suggests that gas hydrate grades is well explained by acoustic impedance and log data

petrographic geochemical and mycological aspects of miocene coals from the novaky and handlova mining districts slovakia abstract fungi have once again become a topic of interest to coal scientists in their roles as agents of maceral formation recent works have demonstrated that fungi occur in association with woody remains resins and cuticles in coalified materials of a variety of ages in addition to coal balls and compression impression fossils where they are already well known these forms however have only been viewed as cross sections along a polished plane assigning the fungi to family much less determining which fungi they represent is very difficult in this orientation fungal identifications are necessary to the continuance of this research into the origin of coal macerals because of the need to know if macrinite begins to form prior to incorporation into the peat which could be demonstrated by its association with symbiotic and parasitic rather than saprophytic fungi this study examines the fungal remains recovered from eight coal samples from miocene age coals in the novaky and handlova mining districts of slovakia with the aim of making this distinction these samples were collected in slovakia as part of the us geological survey s world coal quality inventory program and provided to the authors the samples were processed using the o keefe technique for subbituminous coals and mounted for observation in transmitted light forms were identified using published works and consultation with a modern mycologist forms recovered through palynologic processing were compared to and correlated with forms seen in cross section under reflected light

ground based measurements of spatial and temporal variability of snow accumulation in east antarctica the east antarctic ice sheet is the largest highest coldest driest and windiest ice sheet on earth understanding of the surface mass balance smb of antarctica is necessary to determine the present state of the ice sheet to make predictions of its potential contribution to sea level rise and to determine its past history for paleoclimatic reconstructions however smb values are poorly known because of logistic constraints in extreme polar environments and they represent one of the biggest challenges of antarctic science snow accumulation is the most important parameter for the smb of ice sheets smb varies on a number of scales from small scale features sastrugi to ice sheet scale smb patterns determined mainly by temperature elevation distance from the coast and wind driven processes in situ measurements of smb are performed at single points by stakes ultrasonic sounders snow pits and firn and ice cores and laterally by continuous measurements using ground penetrating radar smb for large regions can only be achieved practically by using remote sensing and or numerical climate modeling however these techniques rely on ground truthing to improve the resolution and accuracy the separation of spatial and temporal variations of smb in transient regimes is necessary for accurate interpretation of ice core records in this review we provide an overview of the various measurement techniques related difficulties and limitations of data interpretation describe spatial characteristics of east antarctic smb and issues related to the spatial and temporal representativity of measurements and provide recommendations on how to perform in situ measurements

modeled seasonal variations of firn density induced by steady state surface air temperature cycle seasonal variations of firn density in ice sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn a recent high resolution mm scale density profile measured along a 181 m core from antarctica showed small scale density variations with a clear seasonal cycle that apparently was not related to seasonal variations in deposition or known near surface processes gerland and others 1999 a recent model of surface elevation changes zwally and li submitted produced a seasonal variation in firn densification and explained the seasonal surface elevation changes observed by satellite radar altimeters in this study we apply our 1 d time dependent numerical model of firn densification that includes a temperature dependent formulation of firn densification based on laboratory measurements of grain growth the model is driven by a steady state seasonal surface temperature and a constant accumulation rate appropriate for the measured antarctic ice core the modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid summer with the highest temperature history compress to the highest density and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density the initial amplitude of the seasonal difference of about 0 13 reduces to about 0 09 in five years and asymptotically to 0 92 at depth which is consistent with the core measurements

impurity controlled densification a new model for stratified polar firn a new densification model which simulates the effect of impurities on the densification of polar firn is presented the classical densification models of herron and langway 1980 and pimienta and barnola barnola and others 1991 are modified by assuming that the activation energy for deformation is reduced by the impurities motivated by recent observations the impurity effect is formulated on an empirical basis using the seasonally varying ca2 ion concentration excellent agreement between simulated and measured high resolution density profiles confirms the new approach the same parameterization applies for greenland and antarctica despite the one order of magnitude difference in impurity concentration the new models allow us for the first time to simulate the density layering in firn down to the firn ice transition our results emphasize the importance of impurities and density layering for the air entrapment and for dating gas records of deep ice cores in particular for glacial climate conditions where the impurity concentrations are 10 100 fold higher than in modern firn

light propagation in firn application to borehole video borehole optical stratigraphy bos is a borehole video system and processing routine for investigating polar firn bos records brightness variations in the firn and is effective at identifying stratigraphic markers bos brightness logs have been used to count annual layers and measure vertical strain even though a specific cause of the brightness variations has not been determined here we combine two models of light transport to examine potential errors with bos and identify improvements which will allow the system to estimate optical grain size we use a monte carlo radiative transfer model to estimate the influence of firn microstructure variations on borehole reflectance we then use a ray tracing algorithm to model the multiple reflections within the borehole that cause measured brightness variations multiple reflections cause the brightness measured at a point on the borehole wall to not necessarily be equal to the local wall reflectance the ray tracing further shows that wall imperfections or variations in the camera position can produce brightness variations that are unrelated to changes in firn properties smooth walls and good stabilization of the camera help ensure that brightness variations result from variations in firn properties and thus are a measure of firn stratigraphy rather than artifacts

grain size evolution of polar firn a new empirical grain growth parameterization based on x ray microcomputer tomography measurements firn microstructure properties from six different sites in greenland and antarctica are investigated by means of x ray microcomputer tomography the optical effective radius is calculated from the specific surface area ssa and used as a measure of grain size it is shown that the recently introduced spherical approximation of firn grains using the effective radius r eff is representative of grain size in the microwave frequency region the measured profiles show the well known increase of grain size with depth at all sites where the increase is largest at near surface depths a large variability in grain size on the decimeter to centimeter scale as a result of different grain properties of single layers is superimposed on the overall trend at each site a simple empirical parameterization of grain size evolution is developed which allows the rapid grain growth in the uppermost layers of the firn to be predicted the growth is driven by strong seasonal and diurnal temperature gradients the model can be used to simulate grain size profiles required by models of firn microwave interaction e g for retrieval of accumulation rates from satellite microwave sensors in a more realistic fashion