the us geological survey s national coal resource assessment the results abstract the us geological survey and the state geological surveys of many coal bearing states recently completed a new assessment of the top producing coal beds and coal zones in five major producing coal regions the appalachian basin gulf coast illinois basin colorado plateau and northern rocky mountains and great plains the assessments which focused on both coal quality and quantity utilized geographic information system technology and large databases over 1 600 000 million short tons of coal remain in over 60 coal beds and coal zones that were assessed given current economic environmental and technological restrictions the majority of us coal production will occur in that portion of the assessed coal resource that is lowest in sulfur content these resources are concentrated in parts of the central appalachian basin colorado plateau and the northern rocky mountains

coal characteristics elemental composition and modes of occurrence of some elements in the isaalan coal balikesir nw turkey abstract this study uses coal petrography micro ftir mineralogical and geochemical analyses to determine the coal characteristics and controlling factors of elemental enrichments in the isaalan coal nw turkey the obtained data show that this subbituminous coal has a relatively low ash yield avg 19 high hydrogen content avg 5 4 and total s content avg 2 4 on an air dry basis the maceral composition along with micro ftir data on ulminite suggests that lignin and resin rich vegetation was predominant the coal facies data imply the precursor peat was accumulating under mesotrophic anoxic conditions where water level was high and fluctuating the mineralogical composition of the bulk coal samples is composed mainly of quartz pyrite and clay minerals and lesser amounts of feldspars and carbonates the statistical analysis of the bulk compositional data shows the major elements including al fe k na mg p and the vast majority of trace elements have inorganic affinity whereas b presumably has organic affinity the trace element concentrations are variable and especially as and elements including b ba cr cs ni sb and v are enriched compared to most world coals the enrichments and distributions of cr cs ni and v were controlled by clastic inputs into a palaeomire whereas as enrichments were controlled mainly by epigenetic and to a lesser extent syngenetic factors introduced so42 and as rich surface and groundwater from the basin margin area along with anoxic conditions in the palaeomire resulted in syngenetic formation of as bearing pyrite the circulating intra seam solutions later liberated as from syngenetically formed pyrite which resulted in as and ni rich overgrowths around framboidal and massive pyrite crystals these solutions could also easily mobilize b that was absorbed by organic matter therefore b enrichment appears to be related to epigenetic factors tectonic activities during coalification allowed hydrothermal solutions from neighbouring epithermal mineralisation to penetrate and circulate along with underground waters that leached overlying volcanoclastic volcanic strata and supplied a number of elements to the studied coal thus infilling as bearing pyrite and silica were formed mainly during coalification all these results suggest that as enrichment in the study area is more likely a combination of epigenetic factors and syngenetic detrital rather than volcanogenic contributions as suggested earlier for some other turkish coal deposits

mechanisms of melange formation examples from sw japan and southern scotland abstract the formation of synthetic riedel shears either as discrete faults or ductile shear zones is important in the fragmentation of layers to form melanges the magnitude of longitudinal and shear strain necessary for this fragmentation has been assessed using a simple rigid domino model for layer parallel shear the strain required for layer fragmentation is a function of block aspect ratio and initial fracture dip relative to layering layer stretching can occur during simple shear if folds are developed but a component of extension parallel to the shear zones reduces the strain required for fragmentation simple models of this type break down when there is a component of dilation across the melange block bounding fractures allowing shale matrix infill or mineral vein growth some melanges show evidence in the form of symmetrical structures of a more coaxial deformation history and this may in part reflect deformation partitioning between sandstone and shale layers other mechanisms of melange formation include the development of out of sequence thrusts cutting through already dipping beds the causes of strike parallel extension are tentatively related to large scale evidence of arc parallel forearc stretching

balanced cross sections and their implications for the deep structure of the northwest alps reply abstract the structure of the northwest external french alps around the internal belledonne and mont blanc massifs in the beaufortain area can be explained by foreland wnw propagating thrust tectonics the internal belledonne massif is interpreted as having developed by imbrication of an originally thin skin of basement with a mesozoic cover above this massif all thrusts tend to climb lateral sections to the south to converge with the frontal pennine thrust the southern termination of the mont blanc massif is merely a spectacular example of such a lateral ramp

sulfur in coals a review of geochemistry and origins geochemical studies of sulfur in coals comprise several major aspects relating to the nature and origin of sulfur in coals including the abundance and distribution of sulfur in coal seams abundance of sulfur in coal lithotypes and macerals characteristics and geochemical significance of sulfur containing organic compounds sulfur isotopic studies relating to the sources of sulfur in coals and sedimentary environments controlling the geochemistry of sulfur in coal a review of the evidence suggests that the variation of sulfur in coals is closely related to the depositional environments of coal seams for low sulfur coal 1 s sulfur is derived primarily from parent plant material for medium sulfur 1 to 3 s and high sulfur 3 s coals there are two major sources of sulfur 1 parent plant material and 2 sulfate in seawater that flooded peat swamps abundances of sulfur in coal are largely controlled by the degree of seawater influence during peat accumulation and by postdepositional changes diagenesis in high sulfur coals seawater sulfate diffuses into the peat which is subsequently reduced by bacteria into hydrogen sulfide polysulfides and elemental sulfur reaction of hydrogen sulfide with ferrous iron generates fine pyrite crystals and mackinawite fes0 9 mackinawite reacts with elemental sulfur to converts to greigite fe3s4 and then to framboidal pyrite the reduced sulfur species in the peat hydrogen sulfide elemental sulfur and polysulfides react with the organic matter to form organic sulfur compounds during coal diagenesis nodular pyrite forms permineralized peat was formed during diagenesis which contains appreciable fraction of pyrite after coal is solidified pyrite can deposit in the cleats from circulating groundwater epigenetic pyrite veins may be deposited from basinal fluids thus pyrite forms during various stages of coal formation from peat to coal as well as late epigenetic activity the relationships between sulfur abundance in coal seams and depositional environments of coals were reviewed for cases from the u s china u k germany hungary turkey indonesia and brazil in most cases low sulfur coals formed in a fluvial environment and high sulfur coals were deposited in seawater influenced environments there are exceptions for example turkish lignites formed in freshwater environments are high sulfur sulfur sources other than seawater are needed for these high sulfur coals the superhigh organic sulfur shos coals are highly enriched in organic sulfur but depleted in pyritic sulfur the shos coals were deposited in sulfur rich iron poor environments such as carbonate platforms or in an iron poor and clastic starved environment in which algae accumulate speciation of organic sulfur compounds in coal appears to be related to coal rank thiophenic compounds are more abundant in bituminous coal and anthracite than in low rank coals

arsenic and lead concentrations in the pond creek and fire clay coal beds eastern kentucky coal field abstract the middle pennsylvanian breathitt formation westphalian b pond creek and fire clay coal beds are the 2 largest producing coal beds in eastern kentucky single channel samples from 22 localities in the pond creek coal bed were obtained from active coal mines in pike and martin countries kentucky and a total of 18 fire clay coal bed channel samples were collected from localities in the central portion of the coal field the overall objective of this study was to investigate the concentration and distribution of potentially hazardous elements in the fire clay and pond creek coal beds with particular emphasis on as and pb 2 elements that are included in the 1990 clean air act amendments as potential air toxics the 2 coals are discussed individually as the depositional histories are distinct the fire clay coal bed having more sites where relatively high s lithologies are encountered in an effort to characterize these coals 40 whole channel samples excluding 1 cm partings were analyzed for major minor and trace elements by x ray fluorescence and proton induced x ray emission spectroscopy previously analyzed samples were added to provide additional geographic coverage and lithotype samples from one site were analyzed in order to provide detail of vertical elemental trends the as and pb levels in the fire clay coal bed tend to be higher than in the pond creek coal bed one whole channel sample of the fire clay coal bed contains 1156 ppm as ash basis with a single lithotype containing 4000 ppm as ash basis most of the as and pb appears to be associated with pyrite which potentially can be removed in beneficiation particularly coarser pyrite disseminated finer pyrite may not be completely removable by cleaning in the examination of pyrite conducted in this study it does not appear that significant concentration of as or pb occurs in the finer pyrite forms the biggest potential problem of as or pb enriched pyrite is therefore one of refuse disposal

a model for the deep structure of the moine thrust zone seismic refraction and electrical conductivity profiles across northern scotland together with geological and other geophysical data are interpreted in terms of the deep structure of this part of the orthotectonic caledonides our preferred interpretation is that the moine thrust zone extends to the base of the crust and the caledonian front is steep this contrasts with recently proposed ultra thin skinned solutions the results of the recently completed moist deep seismic reflection experiment should inter alia test our hypothesis in order to test the geometrical feasibility of our interpretation balanced sections have been constructed to illustrate the crustal evolution of the region during the caledonian orogeny these sections permit estimates to be made of crustal shortening thickening and erosion our model requires that the n highlands were once overlain by major exotic nappes which by analogy with nw newfoundland may have been ophiolitic the proposed regional structural pattern comprises a duplex of crustal dimensions we suggest that crustal duplex development is an important mechanism in the orogenic deformation of previously thinned and extended passive continental margins

distribution of arsenic selenium and other trace elements in high pyrite appalachian coals evidence for multiple episodes of pyrite formation abstract pennsylvanian coals in the appalachian basin host pyrite that is locally enriched in potentially toxic trace elements such as as se hg pb and ni a comparison of pyrite rich coals from northwestern alabama eastern kentucky and west virginia reveals differences in concentrations and mode of occurrence of trace elements in pyrite pyrite occurs as framboids dendrites or in massive crystalline form in cell lumens or crosscutting veins metal concentrations in pyrite vary over all scales from microscopic to mine to regional because trace elements are inhomogeneously distributed in the different morphological forms of pyrite and in the multiple generations of sulfide mineral precipitates early diagenetic framboidal pyrite is usually depleted in as se and hg and enriched in pb and ni compared to other pyrite forms in dendritic pyrite maps of as distribution show a chemical gradient from as rich centers to as poor distal branches whereas se concentrations are highest at the distal edges of the branches massive crystalline pyrite that fills veins is composed of several generations of sulfide minerals pyrite in late stage veins commonly exhibits as rich growth zones indicating a probable epigenetic hydrothermal origin selenium is concentrated at the distal edges of veins a positive correlation of as and se in pyrite veins from kentucky coals and of as and hg in pyrite filled veins from alabama coals suggests coprecipitation of these elements from the same fluid in the kentucky coal samples n 18 as and se contents in pyrite filled veins average 4200 ppm and 200 ppm respectively in alabama coal samples as in pyrite filled veins averages 2700 ppm n 34 whereas as in pyrite filled cellular structures averages 6470 ppm n 35 in these same alabama samples se averages 80 ppm in pyrite filled veins but was below the detection limit in cell structures in samples of west virginia massive pyrite as averages 1700 ppm and se averages 270 ppm n 24 the highest concentration of hg 102 ppm is in alabama pyrite veins improved detailed descriptions of sulfide morphology sulfide mineral paragenesis and trace element concentration and distribution allow more informed predictions of 1 the relative rate of release of trace elements during weathering of pyrite in coals and 2 the relative effectiveness of various coal cleaning procedures of removing pyrite for example trace element rich pyrite has been shown to be more soluble than stoichiometric pyrite and fragile fine grained pyrite forms such as dendrites and framboids are more susceptible to dissolution and disaggregation but less amenable to removal during coal cleaning

an appalachian isochron a kaolinized carboniferous air fall volcanic ash deposit tonstein the fire clay tonstein is a kaolinized airfall volcanic ash bed that was deposited in a widespread late carboniferous peat forming mire eleven samples from kentucky and west virginia spanning a distance of 200 km and two samples from tennessee and virginia indicate a characteristic mineralogical signature as compared with other appalachian tonsteins consisting of well crystallized kaolinite beta quartz crystal paramorphs sanidine ilmenite zircon and brookite detrital illite and quartz are rarely present or are in very small amounts which indicates rapid deposition in a mire several normal graded cycles in this tonstein suggest repeated episodes of pyroclastic activity that produced a composite ash layer a high silica alkalic rhyolitic source is suggested by the geochemistry of immobile elements and by electron probe analyses of glass inclusions in volcanic quartz from the fire clay tonstein the rare earth element plots chondrite normalized of the tonstein show a pronounced negative eu anomaly and relatively high concentrations of zr and th which are both indicative of a rhyolitic source probe analyses of the fire clay glass inclusions from four states indicate a chemically identical high silica rhyolite with peraluminous affinities 40 ar 39 ar sanidine plateau dating indicates an age of 312 1 ma for the fire clay tonstein which is consistent with previous 40 ar 39 ar dates for this tonstein this age is in agreement with a late westphalian b age in the european carboniferous chronostratigraphy on the basis of an age of 311 ma for the westphalian b c boundary a new isopachous map of the fire clay ash fall deposit indicates an area of 37 000 km 2 and a probable source to the present day southwest the deposit has a minimum preserved compacted volume of 2 8 km 3 which corresponds to an original uncompacted volume of about 20 km 3 this preserved volume indicates an ultraplinian volcanic explosion pindell and dewey 1982 proposed an andean type arc in this block during the late carboniferous prior to south american north american plate collision we hypothesize an associated back arc caldera system in the yucatan block to explain the high silica potassic rhyolitic ash that gave rise to the fire clay tonstein

large scale sediment underplating in the makran accretionary prism southwest pakistan field relations in the emergent part of the makran accretionary prism show that a mid miocene to early pliocene slope and shelf sedimentary sequence was deposited directly on abyssal plain turbidites without any detectable stratigraphic or structural discordance sedimentological evidence for rapid shoaling however indicates that the underlying sediment column was tectonically thickened by a factor of between two and three during this period this can be explained by large scale underthrusting and underplating of sediment a mode of accretion that is also favored by mass balance considerations the visible deformation in the coastal makran occurred when the region was 70 100 km north of the contemporary prism front

sensitivity analysis of data related factors controlling ava simultaneous inversion of partially stacked seismic amplitude data application to deepwater hydrocarbon reservoirs in the central gulf of mexico we consider the inversion of synthetic and recorded seismic amplitude variation with angle ava data to appraise the influence of several data related factors that control the vertical resolution and accuracy of the estimated spatial distributions of elastic properties we use measurements acquired in deepwater hydrocarbon reservoirs in the central gulf of mexico to generate synthetic seismic amplitude data and evaluate inversion results with both synthetic and recorded seismic amplitudes detailed sensitivity analysis of synthetic amplitude data indicates that even in the most ideal scenario perfectly migrated data isotropic media noise free seismic amplitude data sufficient far angle coverage and accurate estimates of angle dependent wavelets and low frequency components input elastic models are not reconstructedaccurately by the inversion of synthetic seismic amplitudes we attribute this result to the relatively low vertical resolution of the seismic amplitude data p wave impedance is the most

use of laser ablation icp ms to determine trace element distributions in coals with special reference to v ge and al laser ablation icp ms has been used to produce element profiles from polished coal samples the elements analysed v ge ni cu zn sr and ba were those known to have an organic association with the addition of al and fe as controls on the clay and pyrite abundances the element profiles were compared with the petrography and a statistical analysis was also carried out sporinite was found to have low trace element concentrations inertinite higher concentrations of detrital elements and vitrinite higher concentrations of v ge and al the relationships between these elements are explored and all are thought to be present in the organic matter and not as minerals it is thought that these elements became concentrated during diagenesis with the possibility that some of the al could be residual the cu ni ratio in the pyrite is relatively constant suggesting constant ionic proportions during diagenesis and possibly a seawater source

development of conjugate shear bands during bulk simple shearing abstract in rocks possessing a strong planar fabric shear bands of constant shear sense and oriented at an oblique angle to the foliation are considered by many authors to be characteristic of a non coaxial bulk deformation history whereas conjugate shear bands are considered to indicate coaxial shortening however in two areas where bulk deformation history appears to be non coaxial cap corse corsica and ile de groix brittany conjugate shear bands are observed in order to investigate this problem experiments were performed by bulk simple shearing using plasticine as a rock analogue when slip between layers of the model is permitted shear bands of normal fault geometry form with both the same and opposite shear sense as the bulk simple shearing at approximately the same angle with the layering 40 irrespective of layer orientation in the undeformed state for initial orientations of 50 30 and 15 shear bands are initially formed within individual layers and may propagate across layer interfaces when further movement along these is inhibited the existence of conjugate shear bands in corsica and ile de groix is therefore not incompatible with a model of bulk simple shearing for these two regions in field studies one should perhaps exercise care in using shear bands to determine the kind of motion or the sense of bulk shearing

paleoecology of the fire clay coal bed in a portion of the eastern kentucky coal field vertically continuous increment samples of the fire clay coal bed mid middle pennsylvanian late westphalian b collected from a portion of the central appalachian basin were studied palynologically petrographically and geochemically in order to partially reconstruct the paleoecology and processes associated with peat formation in the ancient fire clay paleomire results indicate that four compositional groups can be identified they are 1 a lycospora vitrinite dominant group characterized by high percentages of lycospora and vitrinite macerals and generally low but variable ash yields and sulfur contents 2 a mixed palynoflora high vitrinite group that petrographically is similar to group 1 except that it contains a more diverse palynoflora 3 a mixed palynoflora moderate low vitrinite group characterized by various admixtures of lycopsid fern and calamite miospores increased percentages of liptinite and inertinite macerals and low ash yields and sulfur contents and 4 a mixed palynoflora high ash yield group characterized by high percentages of small lycopsid fern and occasionally calamite and cordaite miospores high liptinite and inertinite contents high ash yields and moderate to high sulfur contents the fire clay coal bed contains a distinctive flint clay parting of probable volcanic origin that naturally divides the bed into two benches these two benches upper and lower are highly disparte in occurrence appearance and composition in the study area the lower bench generally is thin 0 5 m laterally discontinuous and mainly composed of dull mainly durain coal lithotypes ash yields typically are high sulfur contents generally are moderate to high compositional group 4 the mixed palynoflora high ash yield group defines all of the increments examined from the lower bench in contrast the upper bench is thick 0 75 m laterally continous and mainly comprised of bright mainly clarain coal lithotypes overall ash yields and sulfur contents for this bench are generally low although vertical variation is apparent all of the compositional groups occur in the upper bench in some columns notably those that are thick and uninterrupted by clastic partings groups 1 and 4 often occupy basal coal layers and groups 2 and 3 occur in higher layers other columns especially those taken in areas of thin 0 5 m fire clay coal are dominated by groups 1 and 4

energy balance and deformation mechanisms of duplexes abstract a duplex consists of a series of imbricate faults that are asymptotic to a roof thrust and a floor thrust depending on the final orientations of the imbricate faults and the final position of the branch lines a duplex may be hinterland dipping foreland dipping or an antiformal stack the exact geometry depends on various factors such as the initial dimensions of the individual slices horses their lithology the amount of displacement normalized to size of horse on each fault and the mechanics of movement along each fault the energy required in duplex formation can be determined by calculating the total work involved in emplacing each horse this is given by where w t w p w b w g w i wp is the work involved in initiating and propagating a fracture wb is the work involved in basal sliding which may be frictional or some form of ductile flow wg is the work done against gravity during the emplacement of the horse and wi is the work involved in the internal deformation of the horse by calculating and comparing these work terms it is possible to predict the conditions under which the different types of duplexes will form normally the development of a hinterland dipping duplex is most likely however if deformation conditions are favorable displacements on individual imbricate faults may be very large compared to the size of the horses leading to the formation of either antiformal stacks or foreland dipping duplexes

the geochemistry of environmentally important trace elements in uk coals with special reference to the parkgate coal in the yorkshire nottinghamshire coalfield uk abstract the parkgate coal of langsettian age in the yorkshire nottinghamshire coalfield is typical of many coals in the uk in that it has a high sulphur s content detailed information on the distribution of the forms of s both laterally and vertically through the seam was known from previous investigations in the present work 38 interval samples from five measured sections of the coal were comprehensively analysed for major minor and trace elements and the significance of the relationships established using both raw and centered log transformed data the major elements are used to quantify the variations in the inorganic and organic coal components and determine the trace element associations pyrite contains nearly all of the hg as se tl and pb and is also the major source of the mo ni cd and sb the clays contain the following elements in decreasing order of association rb cs li ga u cr v sc y bi cu nb sn te and th nearly all of the rb is present in the clay fraction whereas for elements such as v cu and u a significant amount is thought to be present in the organic matter based on the k vs trace element regression equations only ge and possibly be would appear to have a dominant organic source the trace element concentrations are calculated for pyrite the clay fraction and organic matter for pyrite it is noted that concentrations agree with published data from the yorkshire nottinghamshire coalfield and also that tl concentrations median of 0 33 ppm in the pyrite are greater than either hg or cd unlike these elements tl has attracted less attention and possibly more information is needed on its anthropogenic distribution and impacts on man and the environment a seawater source is thought to be responsible for the high concentrations of s cl and the non detrital trace elements in the parkgate coal indicative of the seawater control is the th u ratio which expresses the detrital to non detrital element contributions using other elements similar ratios can be calculated which in combination offer greater interpretative value

processing inversion and interpretation of a 2d seismic data set from the north viking graben north sea simultaneous elastic impedance inversion is performed on the 2d north viking graben seismic data set used at the 1994 seg workshop on amplitude variation with offset and inversion p velocity vp s velocity vs density logs and seismic data are input to the inversion the inverted p impedance and s impedance sections are used to generate an approximate compressional to shear velocity ratio vp vs section which in turn is used along with water filled porosity swv derived from the logs from two wells to generate fluid estimate sections this is possible as the reservoir sands have fairly constant total porosity of approximately 28 4 so the hydrocarbon filled porosity is the total porosity minus the water filled porosity to enhance the separation of lithologies and of fluid content we map vp vs into swv using an empirical crossplot derived relation this mapping expands the dynamic range of the low end of the vp vs values the different lithologies and fluids are generally well separated in t

footwall geometry and the rheology of thrust sheets abstract the inter relationships between the exact footwall geometry and the rheology of thrust sheets are investigated deviations in the thrust fault surface from an ideal plane will induce a local heterogeneous deformation the resulting deformation processes depend upon the rate of thrust sheet displacement the geometry of the feature causing heterogeneous flow the deformation conditions and the lithologies involved two classes of features are particularly important in causing heterogeneous deformation in thrust sheets the first features are small perturbations on bedding planes which may be inherited sedimentary structures or produced during layer parallel shortening the second class of features are ramps where the thrust sheet climbs up the stratigraphic section displacement over these features causes repeated cyclic straining in the hanging wall during movement the strain rates associated with deformation at perturbations ramps of different geometries and different displacement rates are estimated and used to discuss the influence of footwall geometry on the structural evolution of a thrust sheet particular attention is given to the range of fault rocks and deformation microstructures preserved after movement over a footwall with a complex geometry perturbations are suggested to be important in the localization of ramps either because they create sticking points near the fault tip during propagation or because they induce eventual failure in the hanging wall after the movement over a number of these features raises the accumulated damage to a critical level analysis of the influence of the exact geometry of ramps on deformation processes during displacement leads to two important conclusions firstly the exact geometry of ramps i e the maximum dip angle and the straining distance from a flat to this maximum angle may be used to estimate a maximum displacement rate of the thrust sheet secondly the listric geometry of ramps may be an equilibrium shape adjusted to the displacement rate and the rheology of the hanging wall adjustments towards the final geometry may involve the generation of shortcuts on either hanging or footwall which reduce the imposed deformation rate in the hanging wall during displacement

near and far offset impedances seismic attributes for identifying lithofacies and pore fluids reliably predicting lithologic and saturation heterogeneities is a key problem in reservoir characterization this study shows how near and far offset seismic impedance can be used to classify lithologies and pore fluids the near offset seismic stack approximates a zero offset section giving an estimate of the normal incidence acoustic impedance ai v the far offset stack gives an estimate of a vp vs related elastic impedance ei attribute equivalent to the acoustic impedance for non normal incidence these attributes can be computed from log data well data can be used prior to seismic inversions to test the feasibility of using ai ei attributes for lithofacies identification bi variate ai ei probability distribution functions can be estimated from logs to obtain classification success rate for each facies success rate is a measure of the value of far offset data for reservoir characterization examples are presented from north sea gulf of mexico and australia

relations between sill intrusions and bedding parallel extensional shear zones in the mid continent rift system of the lake superior region abstract the mid continent rift system is a continuous u shaped feature extending from kansas north through the lake superior region and then south through michigan the logan sills on the northwest side of the lake were intruded during the rifting stage 1109 ma deformation features in the country rock adjacent to the logan sills indicate two episodes of shear strain the first consists of minor thrusts and mesoscopic shear bands both suggesting top to the south southwest movement parallel to the bedding the second rotates the previously formed shear bands in the opposite sense top to the north northeast and is localized at the basal contact between the sills and the country rock we attempt to explain the relations observed with a tectonic model in which sill intrusions take advantage of bedding parallel shear zones that are the surface expression of a south dipping detachment plane the detachment plane steps up in the layered proterozoic sedimentary sequence and allows extension during rifting in this scenario the first episode of shear strain might be related to bedding parallel extension and the second to shear stress induced by the intrusion of magma along the detachment from the south the polarity of both events is supported by small scale kinematic indicators such as veins fiber growths and foliation

geochemistry petrology and palynology of the pond creek coal bed northern pike and southern martin counties kentucky abstract the geochemistry petrology and palynology of the duckmantian age pond creek coal bed were investigated in northern pike and southern martin counties eastern kentucky the coal bed exhibits significant vertical variation in the investigated geochemical parameters with many diagenetic overprints of the original geochemistry included in the range of geochemical signatures are the presence of elements particularly tio 2 and zr suggesting the detrital influences at the time of deposition of a low vitrinite durain a high cao zone with elevated b be both suggesting marine influence in a lithotype in the middle of the coal bed and the postdepositional emplacement of pyrite in the uppermost lithotype individual lithotypes each representing distinct depositional environments all complicated to some degree by diagentic overprints comprise the complex history of the coal bed

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

weighted stacking for rock property estimation and detection of gas amplitude versus offset concepts can be used to generate weighted stacking schemes here called geo stack which can be used in an otherwise standard seismic data processing sequence to display information about rock properties the zoeppritz equations can be simplified and several different approximations appear in the literature they describe the variation of p wave reflection coefficients with the angle of incidence of a p wave as a function of the p wave velocities the s wave velocities and the densities above and below an interface using a smooth representative interval velocity model from boreholes or velocity analyses and assuming no dip the angle of incidence can be found as a function of time and offset by iterative ray tracing in particular the angle of incidence can be computed for each sample in a normal moveout corrected cmp gather the approximated zoeppritz equation can then be fitted to the amplitudes of all the traces at each time sample of the gather and certain rock properties can be estimated the estimation of the rock properties is achieved by the application of time and offset variant weights to the data samples before stacking the properties which can be displayed by geo stack are p wave reflectivity or true zero offset reflectivity s wave reflectivity and the reflectivity of p wave velocity divided by s wave velocity or pseudo poisson s ratio reflectivity if assumptions are made about the relation between p wave velocity and s wave velocity for water bearing clastic silicate rocks then it is possible to create a display which highlights the presence of gas

analysis and interpretation of seismic data from thin reservoirs northwest java basin indonesia a detailed analysis and interpretation is performed of a 2 d seismic line over a sequence of thin reservoirs in the upper cibulakan formation in the northwest java basin most well sites in this area are selected to be structures near fault zones as faults are assumed to be the main hydrocarbon migration paths amplitude variation with offset analysis is little used because of contamination by thin layer tuning effects attribute analysis impedance inversion and full wavefield modeling suggest that gas reservoirs are detectable even when they are less than their tuning thickness as they correspond to acoustic impedance anomalies and low instantaneous frequency the presence of hydrocarbons can also be detected by anomalous behavior in crossplots of acoustic impedance versus density and p wave velocity sandstone reservoirs show low velocity and low impedance two dimensional p velocity and density distributions resulting from impedance inversion produce synthetic elastic common source gathers that disp

geochemistry of the pond creek coal bed eastern kentucky coalfield the pond creek coal bed middle pennsylvanian breathitt formation is an important low sulfur resource in pike and martin countries in the eastern kentucky coalfield the mined area is crossed by the n20 e trending belfry anticline the pond creek coal bed has a higher sulfur content on the west side of the anticline the vertical trends in the ash geochemistry also vary across the anticline the sites to the east of the anticline represent deposition of peat through periods of relative stability with slow deposition bright lithotypes interspersed with periods of relatively rapid clastic deposition dull lithotypes both generally removed from marine influence comparison of elemental trends between the lowest bright lithotype and the second bright lithotype suggest that the swamp became less acidic with time an upward decrease in minor element concentration may be related to the influx of clays and other silicates present in the bone lithotype this bone may have acted as a relatively low nutrient soil for the growth of the plants which contributed to the overlying bright lithotype the sites to the west of the anticline were subjected to a greater marine influence than the eastern sites high k2o al2o3 ratios at the bottom and top of the coal bed and a high tio2 zr dull clarain near the bottom of the coal point to clastic influences on the geochemistry the relatively high cao percentages in the middle third of the coal bed suggest deposition at near neutral ph the upper third of the coal bed was dominated by syngenetic and epigenetic pyrite emplacement

rock lithology and porosity determination from shear and compressional wave velocity data examined in this study are previously published laboratory shear s and compressional p wave velocity measurements on water saturated sandstone calcareous sandstone dolomite and limestone cores as well as laboratory porosity measurements on the sandstone and limestone cores sandstone and limestone porosities range from 092 to 299 and from 006 to 229 respectively differential pressure was varied from 500 to 6000 psi corresponding to approximate burial depths from 290 to 3460 m respectively sandstone limestone and dolomite are effectively separated by poisson s ratio or equivalently by the ratio of p to s wave velocity separation of sandstone and limestone appears to result from the difference in of the matrix material namely quartz 056 and calcite 316 respectively an empirical function 1 v a b was fit by regression analysis to sandstone and limestone velocity vs and vp versus porosity values at each differential pressure in this equation a and b are const

mineralogical and geochemical compositions of late permian coals and host rocks from the guxu coalfield sichuan province china with emphasis on enrichment of rare metals abstract this paper reports the geochemical and mineralogical compositions of the late permian no 25 coal semi anthracite and its host rocks roof and floor strata from the guxu gulin xuyong coalfield sichuan province china the coal is characterized by medium sulfur content average 2 73 and has an average ash yield of 20 95 in contrast to other late permian coals from southwestern china that are enriched in sc v cr co ni and cu the no 25 coal does not contain an abundance of these transition elements but is rich in lithophile elements be y nb zr hf and u the elevated concentrations of trace elements in the no 25 coal were probably derived from the felsic intermediate rocks at the top of the emeishan basalt sequence rather than from the emeishan mafic basalts the floor strata of the no 25 coal can be divided into two sub sections the upper sub section of the sequence immediately below the no 25 coal consists of material with a felsic intermediate composition probably derived from terrigenous sources and the lower sub section is composed of mafic tuff the terrigenous mineral matter in the no 25 coal appears to have the same sediment source region as the upper sub section of the floor strata based on their similar geochemical compositions the roof strata of the no 25 coal are more quartzose and were probably derived from a different sediment source region the mineral matter in the coal is dominated by kaolinite and to a lesser extent calcite and pyrite the roof and floor strata each have quite different mineralogy with kaolinite dominant in the latter and illite kaolinite and quartz in the former pyrite contents are variable both in the coal and in the host rocks the floor strata and the coal have been affected by hydrothermal solutions leading to the enrichment of rare earth elements and yttrium rey nb ta zr hf and u the rey in the coal and floor strata as well as the nb ta zr hf and u in the floor strata represent potentially economic rare metal resources

lp norm deconvolution1 the purpose of deconvolution is to retrieve the reflectivity from seismic data to do this requires an estimate of the seismic wavelet which in some techniques is estimated simultaneously with the reflectivity and in others is assumed known the most popular deconvolution technique is inverse filtering it has the property that the deconvolved reflectivity is band limited band limitation implies that reflectors are not sharply resolved which can lead to serious interpretation problems in detailed delineation to overcome the adverse effects of band limitation various alternatives for inverse filtering have been proposed one class of alternatives is l p norm deconvolution l 1 norm deconvolution being the best known of this class we show that for an exact convolutional forward model and statistically independent reflectivity and additive noise the maximum likelihood estimate of the reflectivity can be obtained by l p norm deconvolution for a range of multivariate probability density functions of the reflectivity and the noise the l norm corresponds to a uniform distribution the l 2 norm to a gaussian distribution the l 1 norm to an exponential distribution and the l 0 norm to a variable that is sparsely distributed for instance if we assume sparse and spiky reflectivity and gaussian noise with zero mean the l p norm deconvolution problem is solved best by minimizing the l 0 norm of the reflectivity and the l 2 norm of the noise however the l 0 norm is difficult to implement in an algorithm from a practical point of view the frequency domain mixed norm method that minimizes the l 1 norm of the reflectivity and the l 2 norm of the noise is the best alternative l p norm deconvolution can be stated in both time and frequency domain we show that both approaches are only equivalent for the case when the noise is minimized with the l 2 norm finally some l p norm deconvolution methods are compared on synthetic and field data for the practical examples the wide range of possible l p norm deconvolution methods is narrowed down to three methods with p 1 and or 2 given the assumptions of sparsely distributed reflectivity and gaussian noise we conclude that the mixed l 1 norm reflectivity l 2 norm noise performs best however the problems inherent to single trace deconvolution techniques for example the problem of generating spurious events remain for practical application a greater problem is that only the main well separated events are properly resolved

arsenic bearing pyrite and marcasite in the fire clay coal bed middle pennsylvanian breathitt formation eastern kentucky abstract arsenic concentrations determined on 11 lithotype samples from the middle pennsylvanian breathitt group fire clay coal bed leslie county ky range from 1 to 418 ppm whole coal basis the 11 lithotype samples which vary in thickness from 4 to 18 cm were sampled from a continuous 1 38 m channel sample and were selected based on megascopic appearance vitrain rich versus attrital rich a lithotype that contains 418 ppm as is located near the top of the coal bed and is composed of 10 5 cm of bright clarain bands containing fusain that within short distances grade laterally into fe sulfide bands to determine the mode of occurrence of as in this lithotype the coal was examined with scanning electron microscopy and analyzed by energy dispersive x ray fluorescence massive framboidal cell filling cell wall replacement and radiating forms of fe sulfide were observed in the high as lithotype many of the radiating fe sulfide forms and one of the cell wall replacements contained as examination of the grains with optical light microscopy shows that the majority of radiating morphologies are pyrite the remainder are marcasite selected fe sulfide grains were also analyzed by electron microprobe microscopy arsenic concentrations within individual grains range from 0 0 wt to approximately 3 5 wt on the basis of morphology these fe sulfides are presumed to be of syngenetic origin and would probably be removed from the coal during physical coal cleaning thus eliminating a potential source of as from the coal combustion process however because the grains are radiating and have high surface area dissolution and release of as could occur if the pyrite is oxidized in refuse ponds

stick slip model for kink band formation in shear zones and faults abstract differential shear stresses acting along or adjacent to a non planar fault surface or shear zone may cause uneven acceleration during slip alternatively at the initiating and closing stages of motion of parts of a stick slip fault localised shear stresses may be variable stress variation of this nature causes zones of relative compression and tension especially close to the stick zones on the fault in fissile rocks adjacent to the fault kink bands form in zones of local relative compression while stratal extension features such as veins fractures and extensional crenulations might be expected in the corresponding zones of relative tension repetitive motion on the fault should therefore cause the development of a suite of kink bands superimposed on each other and on any complementary extensional structures field evidence indicates that the extensional structures are not developed to the same extent as the kinks perhaps due to ductile flow during layer parallel extension of phyllosilicate rocks the advantages of this model are that it does not require bulk shortening of the shear zone relative to the enclosing less strained rocks nor does it depend on complex stress orientation changes

trace based and geostatistical inversion of 3 d seismic data for thin sand delineation an application in san jorge basin argentina argentina s san jorge basin which straddles the southern provinces of chubut and santa cruz in the heart of patagonia has been producing hydrocarbons since 1907 the region currently accounts for 32 of the country s production the existence and early geologic evolution of the basin is due to the same rift process responsible for the opening of the atlantic ocean in early jurassic times extensive direct faulting and local erosion accompanied the rift evolution thereby facilitating the accumulation of chiefly nonmarine terrigenous sediments well into the early cretaceous at this point andean tectonism became a major source of pyroclastic concentration in the sedimentary column it was also responsible for pervasive batholitic intrusions clastic deposition in the hydrocarbon producing zone is characterized by thick shale laminations of lacustrine and floodplain origin interspersed with much thinner and laterally sparse sand bodies the hydrocarbon reservoirs

geochemistry of environmentally sensitive trace elements in permian coals from the huainan coalfield anhui china abstract to study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the permian period from the huainan coalfield anhui province china borehole samples of 336 coals two partings and four roof and floor mudstones were collected from mineable coal seams major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry icp oes inductively coupled plasma mass spectrometry icp ms and hydride generation atomic absorption spectrometry haas the depositional environment abundances distribution and modes of occurrence of trace elements were investigated results show that clay and carbonate minerals are the principal inorganic constituents in the coals a lower deltaic plain where fluvial channel systems developed successively was the likely depositional environment of the permian coals in the huainan coalfield all major elements have wider variation ranges than those of chinese coals except for mg and fe the contents of cr co ni and se are higher than their averages for chinese coals and world coals vertical variations of trace elements in different formations are not significant except for b and ba certain roof and partings are distinctly higher in trace elements than underlying coal bench samples the modes of occurrence of trace elements vary in different coal seams as a result of different coal forming environments vanadium cr and th are associated with aluminosilicate minerals ba with carbonate minerals and cu zn as se and pb mainly with sulfide minerals

lateral variation in geochemistry petrology and palynology in the elswick coal bed pike county kentucky abstract the middle pennsylvanian langsettian westphalian a elswick coal bed correlative to the upper banner of virginia is a rare example of a mined high sulfur 2 coal in eastern kentucky a region known for low sulfur coals to characterize lateral variation in the geochemistry petrography and palynology of the elswick coal bed three sites were sampled along a southeast northwest transect within a single mine at the southeastern site the lower 101 cm of the 116 cm thick coal is dull generally dominated by durain and dull clarain while all benches at this site fit within the previously defined mixed palynoflora moderate low vitrinite group suggesting a stressed environment of deposition the palynology of the benches of the dull interval show greater diversity than might be expected just from the petrology lithology is generally similar between the sites but each site has some differences in the petrology overall the coal bed shows significant lateral variation in properties at the mine scale some of which can be attributed to the gain or loss of upper and lower lithologies either through an actual physical merging or through the change in character of lithotypes sulfur content varies between the three sites examined for this study site 3 located in the northwestern portion of the study area is characterized by a strikingly high sulfur zone 7 45 in the middle of the coal bed a feature missing at the other sites pyrite and marcasite in a mid seam lithotype at the northwestern site site 3 show signs of overgrowths indicating multiple generations of sulfide emplacement the high sulfur site 3 lithologies all have massive overgrowths of euhedral and framboidal pyrite fracture and cleat fill pyrite and sulfide emplacement in fusinite lumens sulfur is high throughout the mine area but variations are evident in the extent of secondary growth of sulfides

constraints on plate motions in southern pakistan and the northern arabian sea from the focal mechanisms of small earthquakes the focal mechanism and depth were determined for nine small earthquakes m0 1025 dyn cm m 5 5 that occurred in southern pakistan and the northern arabian sea from an analysis of the vertical component of rayleigh waves in combination with limited first motion data focal parameters were determined from the rayleigh waves by using an event pair method of analysis for earthquakes that are located very close to each other 50 km the event pair method is able to remove a significant proportion of propagation effects at all periods in the range of interest 20 50 s for events separated by more than 100 km the propagation effects are reduced for only the longer periods 40 50 s the earthquakes that were studied provide evidence for a model of plate interactions in the vicinity of the southern pakistan triple junction the owen fracture zone is a transform fault that accommodates right lateral motion between the indian and arabian plates the plate boundary in the vicinity of the murray ridge is also partially made up of transform segments that strike subparallel to the owen fracture zone spreading centers may also exist in the vicinity of the murray ridge but were not documented by seismic or other evidence the slip azimuths for earthquakes along this boundary are significantly more northerly than those predicted by various regional and worldwide models of plate motion the arabian plate is being subducted beneath the eurasian plate along the southern coast of pakistan slip vectors for earthquakes along this boundary trend northnortheasterly in general agreement with predicted directions left lateral motion is documented along the boundary between the indian and eurasian plates in southern pakistan the predicted direction of relative motion between these plates is not significantly different from that observed two of the earthquakes studied appear to be intraplate in nature the depth and focal mechanism of one intraplate event which may have occurred within the accretionary prism along the makran coast however are based on limited data the other intraplate earthquake occurred within the sedimentary deposits along the western edge of the indian subcontinent near the indian eurasian plate boundary appendix is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington dc 20009 document b83 009 2 50 payment must accompany order

diffraction imaging by prestack reverse time migration in the dip angle domain prestack image volumes may be decomposed into specular and non specular parts by filters defined in the dip angle domain for space shift extended image volumes the dip angle decomposition is derived via local radon transform in depth and midpoint coordinates followed by an averaging over space shifts we propose to employ prestack space shift extended reverse time migration and dip angle decomposition for imaging small scale structural elements considered as seismic diffractors in models with arbitrary complexity a suitable design of a specularity filter in the dip angle domain rejects the dominant reflectors and enhances diffractors and other non specular image content the filter exploits a clear discrimination in dip between specular reflections and diffractions the former are stationary at the specular dip whereas the latter are non stationary without a preferred dip direction while the filtered image volume features other than the diffractor images for example noise and truncation artifacts are also present synthetic and field data examples suggest that diffractors tend to dominate and are readily recognizable averaging over space shifts in the filter construction makes the reflectors rejection robust against migration velocity errors another consequence of the space shift extension and its angle domain transforms is the possibility of exploring the image in a multiple set of common image gathers the filtered diffractions may be analyzed simultaneously in space shift scattering angle and dip angle image gathers by means of a single migration job the deliverables of our method obviously enrich the processed material on the interpreter s desk we expect them to further supplement our understanding of the earth s interior this article is protected by copyright all rights reserved

elastic properties of gas hydrate bearing sediments downhole measured compressional and shear wave velocities acquired in the mallik 2l 38 gas hydrate research well northwestern canada reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate bearing sediments is as a pore filling constituent as opposed to high elastic velocities predicted from a cementation theory whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities the velocity increase from gas hydrate saturation in the sediment pore space is small both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration similar to the field observed velocities however the weighted equation more accurately describes the compressional and shear wave velocities of gas hydrate bearing sediments a decrease of poisson s ratio with an increase in the gas hydrate concentration is similar to a decrease of poisson s ratio with a decrease in the sediment porosity poiss

mineralogical and geochemical characterization of the saray and pinarhisar coals northwest thrace basin turkey abstract this study investigates the mineralogical and geochemical characteristics of coals from the saray and pinarhisar coalfields in the northwest thrace basin using optical microscopy scanning electron microscopy x ray diffraction and inductively coupled plasma mass spectrometry the saray and pinarhisar coals were deposited in a limnic environment the sulfur content of the coals ranges from 0 3 to 15 3 and high sulfur contents may originate from both seawater and volcanism pyritic and organic sulfur are the dominant sulfur forms 1 2 and 2 7 on average respectively the mineral matter of the coals consists mainly of pyrite barite gypsum muscovite and kaolinite with minor amounts of quartz butlerite tamarugite and rozenite the coals are enriched in trace elements including v 61 ppm on average co 5 85 ppm on average ni 79 ppm on average as 39 2 ppm on average th 3 6 ppm on average and u 6 7 ppm on average based on pearson correlation coefficients ti v cr fe co ni cu se rb au hg pb and th have mainly inorganic affinities r ash elements 0 5 in the pinarhisar coals fe as and au also have inorganic affinities r ash elements 0 5 in the saray coals the element contents and correlation coefficients indicate that the strandja massif the tethyan ophiolite belt and the oldest basement sediments were included in the sediment source region for both coalfields while the strandja massif was the prevailing sediment source region for pinarhisar coalfield

trace elements in the goze delchev coal deposit bulgaria abstract the geochemistry of trace elements in the underground and open pit mine of the goze delchev subbituminous coal deposit have been studied the coals in both mines are highly enriched in w ge and be and at less extent in as mn and y as compared with the world wide clarkes for subbituminous coals ni and ti are also enhanced in the underground coals and zr cr and mo in the open pit mine coals characteristic for the trace element contents in the deposit is a regular variation with depth the following patterns were distinguished for profile i a the element content decreases from the bottom to the top of the bed paralleling ash distribution fe co as sb v y mo cs ree hf ta th p and au b ge and w are enriched in the near bottom and near top coals c in the middle part of the bed the content of k and rb is maximal while that of u is slightly enriched d ba content decreases from the top to the bottom of the bed in profile ii w and be contents decrease from the bottom to the top the near bottom and especially the near roof samples of profile iv are highly enriched in ge while for w the highest is the content of the near bottom sample ge be as mn cl and br are mainly organically associated the organic affiliation is still strong for co b sr ba sb u th mo la ce sm tb and yb in the underground coals and fe co na w sr y and ag in the coals from the open pit mine k rb ti zr hf and ta are of dominant inorganic affinity the chalcophile and siderophile elements correlate positively with fe and each other and may be bound partly with pyrite or other sulphides and iron containing minerals compared statistically by the t criteria the elements na li cu zn pb cr ni co mo fe and be are of higher content in the open pit mine tungsten is the only element of higher concentration in the underground mine the contents of ge as sr v mn y zr and p are not statistically different in both mines it was supposed that there were multiple sources of the trace elements in the deposit the source of the highly enriched elements w ge be and as most probably were the thermal waters in the source area the contemporary mineral springs are of high content of these elements another source were the hosting mesta volcanic rocks which are enriched in sb mo hf u th as li and rb some of the volcanics were hydrothermally altered and enriched or depleted of many elements thus the hydrothermal solutions were also suppliers of elements for the coals it is obvious that the contents distribution and paragenesis of the trace elements in both goze delchev coals reflect the geochemical specialization of the source area including rocks paleo and contemporary thermal waters

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

arsenic in iron disulfides in a brown coal from the north bohemian basin czech republic arsenic in the coal studied is not bound to coal macerals it is concentrated in the inorganic part of coal specifically in the iron sulfides this paper reports the results of five crystal structure refinements that include natural 2 and synthetic 3 sulfides pyrite 3 and marcasite 2 powder 3 and single crystal 2 intensities used in the refinements were obtained by diffraction of x rays 4 and synchrotron radiation 1 the refined occupancy factors of sulfur and the unit cell parameters favor the possibility that as substitutes for s in both disulfides

balanced cross sections and their implications for the deep structure of the northwest alps discussion abstract field evidence around the southwestern termination of the mont blanc basement massif casts doubt on butler s interpretation of the massif as a relatively thin thrust sheet extending over the imbricated dauphind cover a thick skinned model of basement faulting analogous to laramide faulting in the western u s a seems more appropriate for the area

porosity identification using amplitude variations with offset examples from south sumatra abstract this paper describes the use of a relatively new exploration technique in the modeling and interpretation of seismic data the technique holds promise for identification of primary lithology and of local lithological facies variations its underlying principle is that any single reflection within a cdp gather will show an amplitude variation between near and far offset traces given certain physical properties of rocks across the reflecting boundary stacking velocity information above the reflector and the cdp geometry it is possible to model the observed amplitude variation such modeling can result in useful information on lithology two examples will be shown of the application of this technique in the detection of porosity in miocene reefal buildups in south sumatra

slip vectors and fault mechanics in the makran accretionary wedge southwest pakistan the makran is a broadly east west trending arcuate accretionary wedge currently forming where the oceanic floor of the gulf of oman is being subducted north northeastward beneath the south asian margin two traverses across the makran coast ranges extending about 80 km inland from the coastline which lies about 100 km north of the wedge front show that the structure of this region is dominated by large back rotated south directed thrust faults and associated folds related structures include duplexes fault gouge containing reidel shears and melange along fault zones these structures are cut by later north directed backthrusts out of sequence south directed thrusts and apparently conjugate sets of nne trending sinistral and nw trending dextral strike slip faults slip vectors were determined from slickenlines fiber lineations gouge fabrics and riedel shears vectors from early thrusts and bedding parallel slip surfaces corrected for tectonic rotation form a broad south directed concentration lying between the normal to the regional strike varying from 160 to 180 and the present plate convergence vector 200 locally the concentration is bimodal this pattern may represent the interaction between plate forces and body forces in the accretionary wedge the late thrusts have widely variable slip vectors and stair step off the early thrusts they overlap in orientation and slip vector with gently dipping sinistral strike slip faults suggesting that they also stair step in plan off the latter the steep strike slip faults represent the final tectonic stage involving minor n s shortening and longitudinal extension these three stages probably occurred in sequence in any one area but migrated diachronously southward as the wedge grew

sandstone detrital modes in the makran accretionary wedge southwest pakistan implications for tectonic setting and long distance turbidite transportation detrital modes of early miocene to early pliocene sandstones from the makran accretionary wedge in southwest pakistan show a mainly quartzolithic composition with an evolution from the transitional recycled to quartzose recycled the lithic types however indicate two distinct petrofacies accreted abyssal plain turbidites have qp11lvm27lsm62 and lm39lv27ls34 showing a predominant supply from sedimentary and metasedimentary source terranes whereas slope and shelf facies sediments deposited on the accretionary wedge have qp7lvm47lsm47 and lm22lv48ls30 due to an increase of volcanic detritus the detrital modes of the abyssal plain sediments suggest a recycled orogenic source probably the himalayan collision zone the facies and longitudinal dispersal pattern suggest deposition in an oligo miocene analogue of the present indus fan the sediment must have been transported across strike parallel to the transform structure linking the makran wedge to the himalayas chaman ornach nal fault system and fed into the fan at the western end of the subduction zone the detrital modes also show an increase in volcanic detritus with time lv l 0 27 for the early miocene abyssal plain sediments to 0 47 for the slope sequences this may have been derived from late mesozoic volcanic terrains in northern baluchistan or the ladakh himalayas or more probably from the early to middle miocene andesitic volcanic centre in the northern makran

evidence for non plane strain flattening along the moine thrust loch srath nan aisinnin north west scotland we report quartz c axis patterns grain shape fabrics and microstructures for 11 mylonitic quartzites and quartz phyllosilicate schists from a transect across the moine thrust at loch srath nan aisinnin north west scotland in the footwall samples collected more than 42 m normal distance from the thrust surface quartz c axis textures indicate a general flattening strain i e 0 k 1 samples within 19 m normal distance of the thrust are completely recrystallized and exhibit asymmetric c axis patterns recrystallized hanging wall fault rocks exhibit random c axis patterns on the scale of a standard thin section relict footwall grains provide the closest approximation of finite strain they have octahedral shear strains s between 1 10 and 1 47 and exhibit general flattening k values 0 0524 0 659 the long axis of the mean relict grain shape trends parallel to the regional transport direction and plunges gently to the ese in contrast recrystallized footwall grains have a mean grain shape with the longest axis oriented nearly perpendicular to the transport direction furthermore these samples have grain shape k value ranges from 0 157 to 0 295 recrystallized hanging wall grain shapes exhibit the lowest octahedral shear strains s 0 532 0 733 and largest mean k values 0 351 0 961 of this sample set the long axes of the mean recrystallized hanging wall grain shapes are parallel to transport similar to that of relict footwall grains unrecrystallized quartz overgrowths about opaque mineral grains suggest concurrent elongation in all directions within the mylonitic foliation and support the inference of general flattening deformation the mylonitic foliation and penetrative lineation are consistent with a wnw shearing direction however both were folded during later deformation increments recrystallized grains in footwall quartzites suggest a 305 320 azimuth for the shearing direction the best fit axis of the poles to the foliation is 18 145 close to the mean trend plunge of mesoscopic fold hinges at this site 18 151 both suggest a nnw azimuth for the shearing direction thus structural microstructural and fabric indicators suggest a change in the azimuth of the shearing direction from 286 to 331

paleostresses associated with faults of large offset abstract in order to test empirically the limitations of paleostress analysis we used etchecopar s computer program to compute the orientations and relative magnitudes of paleostress principal values in two southern appalachian u s a thrust zones from minor fault and slickenside attitudes in both thrust zones faults are closely spaced many faults have offsets whose magnitudes exceed the distance to adjacent faults of comparable size and deformation was strongly non coaxial while even in the less deformed thrust zone bulk strains due to fault movement have axial ratios as high as 10 1 nearly 75 of the fault slickenside pairs in each thrust zone conform with paleostress tensors that indicate 1 sequential transport parallel compression transport parallel extension and extension oblique to transport and 2 low resolved shear stresses on the thrusts finite strains measured in one thrust zone share a principal plane with the first two tensors and the inclinations of the paleostress and finite strain principal directions in that plane are consistent with thrust parallel shearing relative magnitudes of paleostress and strain principal values do not correlate well moreover the locations and inferred origins of fault slickenside pairs inconsistent with paleostress tensors suggest that stresses in rocks between faults were not as is assumed in paleostress analyses uniform this complexity may also occur in faulted rocks where bulk strains are small paleostress tensors from rocks with large bulk strains may be viable but they must be interpreted cautiously

sulfur sources of sedimentary buckshot pyrite in the auriferous conglomerates of the mesoarchean witwatersrand and ventersdorp supergroups kaapvaal craton south africa large rounded pyrite grains 1 mm commonly referred to as buckshot pyrite grains are a characteristic feature of the auriferous conglomerates reefs in the witwatersrand and ventersdorp supergroups kaapvaal craton south africa detailed petrographic analyses of the reefs indicated that the vast majority of the buckshot pyrite grains are of reworked sedimentary origin i e that the pyrite grains originally formed in the sedimentary environment during sedimentation and diagenesis forty one of these reworked sedimentary pyrite grains from the main vaal basal kalkoenkrans beatrix and ventersdorp contact reefs were analyzed for their multiple sulfur isotope compositions 34s 33s and 36s to determine the source of the pyrite sulfur in addition five epigenetic pyrite samples pyrite formed after sedimentation and lithification from the middelvlei and the ventersdorp contact reefs were measured for comparison the 34s 33s and 36s values of all 41 reworked sedimentary pyrite grains indicate clear signatures of mass dependent and mass independent fractionation and range from 6 8 to 13 8 1 7 to 1 7 and 3 9 to 0 9 respectively in contrast the five epigenetic pyrite samples display a very limited range of 34s 33s and 36s values 0 7 to 4 0 0 3 to 0 0 and 0 3 to 0 1 respectively despite the clear signatures of mass independent sulfur isotope fractionation very few data points plot along the primary archean photochemical array suggesting a weak photolytic control over the data set instead other factors command a greater degree of influence such as pyrite paragenesis the prevailing depositional environment and non photolytic sulfur sources in relation to pyrite paragenesis reworked syngenetic sedimentary pyrite grains pyrite originally precipitated along the sediment water interface are characterized by negative 34s and 33s values suggesting open system conditions with respect to sulfate supply and the presence of microbial sulfate reducers on the contrary most reworked diagenetic sedimentary pyrite grains pyrite originally precipitated below the sediment water interface show positive 34s and negative 33s values suggesting closed system conditions negligible 33s anomalies from epigenetic pyrite suggest that the sulfur was sourced from a mass dependent or isotopically homogenous metamorphic hydrothermal fluid contrasting sulfur isotope compositions were also observed from different depositional environments namely fluvial conglomerates and marine modified fluvial conglomerates the bulk of the pyrite grains from fluvial conglomerates are characterized by a wide range of 34s values 6 2 to 4 8 and small 33s values 0 3 this signature likely represents a crustal sulfate reservoir derived from either volcanic degassing or from weathering of sulfide minerals in the hinterland reworked sedimentary pyrite grains from marine modified fluvial conglomerates share similar isotope compositions but also produce a positive 33s 34s array that overlaps with the composition of archean barite suggesting the introduction of marine sulfur these results demonstrate the presence of multiple sources of sulfur which include atmospheric crustal and marine reservoirs the prevalence of the mass dependent crustal sulfur isotope signature in fluvial conglomerates suggests that sulfate concentrations were probably much higher in terrestrial settings in comparison to marine environments which were sulfate deficient however the optimum conditions for forming terrestrial sedimentary pyrite were probably not during fluvial progradation but rather during the early phases of flooding of low angle unconformities i e during retrogradational fluvial deposition coupled in some cases with marine transgressions immediately following inflection points of maximum rate of relative sea level fall

enrichment of arsenic lead and antimony in balingian coal from sarawak malaysia modes of occurrence origin and partitioning behaviour during coal combustion abstract the concentrations of mineral forming elements and trace elements in coal and coal ashes from balingian coalfield sarawak malaysia were assayed and their modes of occurrence enrichment origin and partitioning behaviour during coal combustion were studied as well balingian coal is high in as cu pb sb th and zn of particular concern are as as high as 181 ppm pb 325 ppm and sb 96 ppm all of which are highly enriched in balingian coal relative to their respective coal clarke values arsenic pb and sb in the coal are mostly organic and to a lesser extent they are bound to discrete minerals in the form of aluminosilicates during coal combustion in the power plant a substantial portion of organically associated as pb and sb in the coal vaporize and are released into the atmosphere whereas ba and mn are highly enriched in the coal ashes as compared to the raw coal the as pb and sb anomalies observed in balingian coal may be related to a large sb as and probably pb mineralization in the vicinity of the coalfield with some localised epigenetic infiltration of these elements from the surrounding rocks by circulating groundwaters

the mechanism and kinetics of the transformation from marcasite to pyrite in situ and ex situ experiments and geological implications despite the natural abundance of pyrite and marcasite and their intergrowth and a wealth of information they can provide on the physical chemical conditions of mineral deposits a complete mechanistic and kinetic study on the phase transformation from the thermodynamically metastable polymorph marcasite to the stable polymorph pyrite is yet to be made this limits the application of marcasite as an indicator mineral for low temperature geological environments here we report results from in situ synchrotron powder x ray diffraction and ex situ anneal quench experiments at 400 540 c demonstrating that the mechanism and kinetics of this transformation depend not only on temperature but also on particle size the presence of water vapor and the presence of pyrite inclusions in marcasite under dry conditions the transformation is limited by surface nucleation and occurs via epitaxial nucleation of pyrite on marcasite with 100 pyrite 101 marcasite and 001 pyrite 010 marcasite in contrast in the presence of water vapor there is little crystallographic orientation relationship between the two phases the transformation is still limited by surface nucleation but modification of the surface properties by water vapor results in a different nucleation mechanism and consequently different kinetics kinetic analysis estimates a half life of 1 5 ma at 300 c for the transformation under dry conditions with small and pyrite free marcasite grains but this estimation should be used with extreme caution due to the complexity of the transformation from synchrotron x ray fluorescence elemental mapping trace elements as and pb play an insignificant role in the transformation however the presence of a fluid phase changes the behavior of pb under dry conditions randomly oriented particles of galena formed in pyrite while under water vapor conditions arrays of nano to microparticles of galena precipitated in pores this study highlights that although the natural occurrence of marcasite can indicate low temperature environments precise estimation of temperature should not be made without considering the influences from various reaction parameters

tracking mercury from the mine to the power plant geochemistry of the manchester coal bed clay county kentucky abstract the high volatile a bituminous manchester coal bed was sampled at five mine sites in central clay county southeastern kentucky the coal bed has a high mercury concentration at certain sites particularly in the high sulfur uppermost lithology whole coal hg contents range up to 0 52 ppm in a sample with 3 36 pyritic sulfur hg is enriched in the upper lithotype at several of the sites arsenic content exceeds 700 ppm ash basis for all of the whole channel samples and exceeds 1000 ppm for several of the lithotype samples regional geochemical trends from an area of approximately 75 60 km were determined using data from this study in combination with data published by the u s geological survey hg as pb and cl contents exhibit highs in the northwestern portion of the region within the smaller area covered by the detailed mine study the two western sites both have a high sulfur upper lithotype containing high levels of as and hg basement structures previously described in the study area could have influenced the regional coal rank and geochemistry possibly acting as conduits for mineralizing fluids

detection of gas in sandstone reservoirs using avo analysis a 3 d seismic case history using the geostack technique the geostack technique is a method of analyzing seismic amplitude variation with offset avo information one of the outputs of the analysis is a set of direct hydrocarbon indicator traces called fluid factor traces the fluid factor trace is designed to be low amplitude for all reflectors in a clastic sedimentary sequence except for rocks that lie off the mudrock line the mudrock line is the line on a crossplot of p wave velocity against s wave velocity on which water saturated sandstones shales and siltstones lie some of the rock types that lie off the mudrock line are gas saturated sandstones carbonates and igneous rocks in the absence of carbonates and igneous rocks high amplitude reflections on fluid factor traces would be expected to represent gas saturated sandstones of course this relationship does not apply exactly in nature and the extent to which the mudrock line model applies varies from area to area however it is a useful model in many basins of the world including the one

trace element abundances in major minerals of late permian coals from southwestern guizhou province china abstract fourteen samples of minerals were separated by handpicking from late permian coals in southwestern guizhou province china these 14 minerals were nodular pyrite massive recrystallized pyrite pyrite deposited from low temperature hydrothermal fluid and from ground water clay minerals and calcite deposited from low temperature hydrothermal fluid and from ground water the mineralogy elemental composition and distribution of 33 elements in these samples were studied by optical microscopy scanning electron microscope equipped with energy dispersive x ray spectrometer sem edx x ray diffraction xrd cold vapor atomic absorption spectrometry cv aas atomic fluorescence spectrometry afs inductively coupled plasma mass spectrometry icp ms and ion selective electrode ise the results show that various minerals in coal contain variable amounts of trace elements clay minerals have high concentrations of ba be cs f ga nb rb th u and zr quartz has little contribution to the concentration of trace elements in bulk coal arsenic mn and sr are in high concentrations in calcite pyrite has high concentrations of as cd hg mo sb se tl and zn different genetic types of calcite in coal can accumulate different trace elements for example ba co cr hg ni rb sn sr and zn are in higher concentrations in calcite deposited from low temperature hydrothermal fluid than in that deposited from ground water furthermore the concentrations of some trace elements are quite variable in pyrite different genetic types of pyrites py a b c d have different concentrations of trace elements and the concentrations of trace elements are also different in pyrite of low temperature hydrothermal origin collected from different locations the study shows that elemental concentration is rather uniform in a pyrite vein there are many micron and submicron mosaic pyrites in a pyrite vein which is enriched in some trace elements such as as and mo the content of trace element in pyrite vein depends upon the content of mosaic pyrite and of trace elements in it many environmentally sensitive trace elements are mainly contained in the minerals in coal and hence the physical coal cleaning techniques can remove minerals from coal and decrease the emissions of potentially hazardous trace elements

relationships between compressional wave and shear wave velocities in clastic silicate rocks new velocity data in addition to literature data derived from sonic log seismic and laboratory measurements are analyzed for clastic silicate rocks these data demonstrate simple systematic relationships between compressional and shear wave velocities for water saturated clastic silicate rocks shear wave veloci ty is approximately linearly related to compressional wave velocity and the compressional to shear velocity ratio decreases with increasing compressional velocity laboratory data for dry sandstones indicate a nearly constant compressional to shear velocity ratio with rigidity approximately equal to bulk modulus ideal models for regular packings of spheres and cracked solids exhibit behavior similar to the observed water saturated and dry trends for dry rigidity equal to dry bulk modulus gassmann s equations predict velocities in close agreement with data from the water saturated

geometry of an outcrop scale duplex in devonian flysch maine we describe an outcrop scale duplex consisting of 211 exposed repetitions of a single bed the duplex marks an early acadian middle devonian oblique thrust zone in the lower devonian flysch of northern maine detailed mapping at a scale of 1 8 has enabled us to measure accurately parameters such as horse length and thickness ramp angles and displacements we compare these and derivative values with those of published descriptions of duplexes and with theoretical models shortening estimates based on line balancing are consistently smaller than two methods of area balancing suggesting that layer parallel shortening preceded thrusting

lanthanide yttrium and zirconium anomalies in the fire clay coal bed eastern kentucky abstract the fire clay coal bed in the central appalachian basin region contains a laterally persistent tonstein that is found in the coal throughout most of its areal extent the tonstein contains an array of minerals including sanidine quartz anatase and euhedral zircon that constitutes strong evidence for a volcanic origin of the parting for this study five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern kentucky inductively coupled plasma mass spectroscopy icp ms analysis of the tonstein and underlying coal collected from four sites in eastern kentucky show that although zr concentrations are high in the tonstein 570 1820 ppm on a coal ash basis cab they are highest in the coal directly underlying the tonstein 2870 4540 ppm cab a similar enrichment pattern is observed in the concentration of y plus the sum of the rare earth elements y ree total y ree concentrations in the five tonstein samples range from 511 to 565 ppm cab however y ree contents are highest in the coals directly underlying the tonsteins values range from 1965 to 4198 ppm cab scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that ree rich phosphate tentatively identified as monazite commonly infills cracks in clays and cells in clarain and vitrain zircon is rare and commonly subhedral on the basis of coal chemistry and grain morphology we suggest that volcanic components in the tonstein were leached by ground water the leachate rich in y and ree precipitated as authigenic mineral phases in the underlying coal

tau p seismic data for viscoelastic media part 2 linearized inversion1 an approach to extraction of viscoelastic parameters from seismic data is implemented and succesfully tested viscoelastic inversion is performed using adaptive damping factors to control the sensitivity of the viscoelastic parameters in relation to the p seismic data a priori information is incorporated through the damping factors as standard deviations of the data and of the viscoelastic model parameters the stability of the inversion process is controlled by the variation of the damping factors as a function of the residual errors and parameter updates at each iteration tests on synthetic and real data show that p and s wave quality factors qp and qs in addition to p and s wave velocities and density cp cs and p can be extracted from p seismic information singular value decomposition analysis demonstrates that estimated qp and qs values are more affected by the presence of data inaccuracies and noise than are those of cp and p cs and qs are not uniquely recovered due to the limited contribution of p s converted waves knowledge of the viscoelastic parameters is of particular importance in accurately describing petrophysical properties of rocks and pore fluids existing in the subsurface this is demonstrated with real data from the gulf of mexico

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

stratal extension in thrust footwalls makran accretionary prism implications for thrust tectonics small scale stratal extension is commonly associated with thrust faults in the makran accretionary prism of southwest pakistan low angle normal faults dipping in the direction of transport relative to the thrust are common in gouge zones and duplexes and may also cut the footwall and hanging wall where they cause stratal extension these faults are probably riedel shears we have studied a broad zone of more complex extensional deformation beneath one bedding parallel thrust the zone disrupts earlier compressional structures and affects a significant volume of the footwall normal faults initiating in a rearward sequence branch off the thrust and cut down into the footwall merging at a lower stratigraphic level part of the thrust displacement was thereby transfe red to that level and fragments of the footwall were detached and transferred southward beneath the hanging wall the latter remained undeformed and accommodation structures are confined to the footwall these effects may have been caused by variations in sliding resistance along the fault if a thrust transfers part or all of its displacement down section along normal faults in this way before eventually cutting back up toward the surface it will detach a rootless fragment of footwall rocks from a position forward of the initial ramp through that horizon this process can be referred to as footwall plucking it can explain rootless basement slices along thrusts for example and it has important implications for section restoration techniques and the interpretation of thrust belts

v p v s and lithology published laboratory investigations suggest an association exists between the ratio of seismic compressional and shear wave velocities vp vs and sedimentary rock lithology comparisons of some theoretical models with these laboratory studies suggest that crack or pore geometry has a stronger effect on observed vp vs values than elastic constants of the minerals comprising the matrix further it can be inferred that the observed association between lithology and vp vs is a result of an association between lithology and distribution of pore and crack shapes direct observation of crack shapes for a variety of lithologies is a next step in strengthening these inferences the present study reviews the empirical relations between vp vs and lithology and examines two published theoretical models of cracked elastic media the models suggest that seismic velocities of sandstones may be controlled by cracks and pores with aspect ratios in the range of 10 1 to 1 dolomite in the range of 10 2 to 10 1 and dens

multiple bench architecture and interpretations of original mire phases examples from the middle pennsylvanian of the central appalachian basin usa abstract coal seams often exhibit lateral and vertical variability in composition when sampled as a whole seam this variability is masked but if a seam is subdivided into correlateable components this variability can be tested and better understood herein an architectural approach is used to divide seams into intra seam components clastic splits and mineral partings as well as persistent fusain and durain layers can be used as intra seam bounding units to subdivide a seam into subdivisions called benches regional examination of lower and middle pennsylvanian age coal seams shows that many contain laterally persistent bounding surfaces that can be used to define multiple benches of coal within each seam inter bench analyses from some of the most extensively mined seams in the central appalachian basin show that individual benches often have different spatial and quality trends hence some component of whole seam variability is a function of changes in the relative contribution of these different benches to the seam as a whole many coal benches also exhibit intra bench variation in coal parameters intra bench variation can be analyzed in terms of parameters such as sulfur content and ash yield in order to address changes in coal quality for regional resource evaluation intra bench variation can also be analyzed in terms of a combination of palynologic petrographic and geochemical parameters termed compositional groups in order to better understand the development of the original mire systems compositional groups are defined by ranges of multiple criteria which are inferred to owe their origin to the mire type in which they formed vertical changes in compositional groups within coal benches can be used to infer paleo edaphic conditions during peat accumulation if seam thickness is a product of bench configuration and trends in compositional groups occur in benches then trends in quality can be marginally predicted based upon seam thickness and inferred bench architecture additionally changes in inter bench and intra bench thickness and compositional profiles can be used to infer original depositional controls such as paleotopography syndepositional structural movement and syndepositional clastic influx for more accurate reserve estimates

fundamentals of seismic rock physics during the past 50 years or so tremendous progress has been made in studying physical properties of rocks and minerals in relation to seismic exploration and earthquake seismology during this period many theories have been developed and many experiments have been carried out some of these theories and experimental results have played important roles in advancing earth sciences and exploration technologies this tutorial paper attempts to summarize some of these results

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

marcasite inversion and the petrographic determination of pyrite ancestry pyrite formed by the inversion of marcasite or by oxidative leaching of pyrrhotite can be recognized in polished sections by the following characteristics compiled from synthetic pyrite after marcasite and natural samples of pyrite after marcasite and after pyrrhotite pyrite formed by inversion from marcasite is characterized by approximately 2 modal percent pore space no by products filling the pores optical anisotropy dark green to dark red anhedral shape and polycrystalline daughter pyrite domains in two orientations relative to the marcasite parent crystal pyrite or marcasite formed by oxidative dissolution as opposed to leaching of pyrrhotite exhibits up to 32 modal percent pore space gaps between the pyrite and parent pyrrhotite pores and gaps filled with by product siderite magnetite hisingerite or other fe bearing phase optically isotropic character for pyrite development of crystal faces and random orientation relative to the parent pyrrhotite marcasite formed by oxidative leaching of fe as opposed to complete dissolution from pyrrhotite also exhibits a large amount of pore space but has preferred orientation relative to the parent pyrrhotite pyrite after marcasite may be used as an indicator of ph 5 and t ca 240 degrees c during deposition of the parent marcasite marcasite precipitated following dissolution of pyrrhotite is also indicative of those conditions during alteration marcasite formed by oxidative leaching of pyrrhotite cannot be used as evidence of those conditions however

reply to comment on how to build an extensional basin in a contractional setting numerical and physical modeling applied to the mejerda basin at the front of the eastern tell of tunisia

separation and imaging of seismic diffractions using migrated dip angle gathers abstractcommon reflection angle migration can produce migrated gathers either in the scattering angle domain or in the dip angle domain the latter reveals a clear distinction between reflection and diffraction events we derived analytical expressions for events in the dip angle domain and found that the shape difference can be used for reflection diffraction separation we defined reflection and diffraction models in the radon space the radon transform allowed us to isolate diffractions from reflections and noise the separation procedure can be performed after either time migration or depth migration synthetic and real data examples confirmed the validity of this technique

amplitude versus offset variations in gas sands seismic reflections from gas sands exhibit a wide range of amplitude versus offset avo characteristics the two factors that most strongly determine the avo behavior of a gas sand reflection are the normal incidence reflection coefficient r0 and the contrast in poisson s ratio at the reflector of these two factors r0 is the least constrained based on their avo characteristics gas sand reflectors can be grouped into three classes defined in terms of r0 at the top of the gas sand class 1 gas sands have higher impedance than the encasing shale with relatively large positive values for r0 class 2 gas sands have nearly the same impedance as the encasing shale and are characterized by values of r0 near zero class 3 sands have lower impedance than the encasing shale with negative large magnitude values for r0 each of these sand classes has a distinct avo characteristic an example of a gas sand from each of the three classes is presented in the paper the class 1 example involves a hartshorn channel s