faulting of rocks in three dimensional strain fields i failure of rocks in polyaxial servo control experiments abstract the dependence of the number of sets of faults and their orientation on the intermediate strain axis is investigated through polyaxial tests reported here and theoretical analysis reported in an accompanying paper in the experiments cubic samples of berea sandstone sierra white and westerly granites and candoro and solnhofen limestones were loaded on their three pairs of faces by three independent mutually perpendicular presses at room temperature two of the presses were servo controlled and applied constant displacement rates throughout the experiment most samples display three or four sets of faults in orthorhombic symmetry these faults form in several yielding events that follow a stage of elastic deformation in many experiments the maximum and the intermediate compressive stresses interchange orientations during the yielding events where the corresponding strains are constant the final stage of most experiments is characterized by slip along the faults

palaeostress superimposition deduced from mesoscale structures in limestone the matelles exposure languedoc france abstract this study investigates the reasons for the superimposition of several maximum principal stress directions 1 in the same area and examines the contrast between unperturbed areas stable direction of 1 and perturbed areas changing 1 direction we studied mesoscale structures on a 1000 m2 continuous limestone exposure near a regional scale strike slip fault local 1 directions were deduced from a high concentration of minor strike slip faults extension fractures and stylolites formed during the pyrenean shortening in languedoc france most of the stylolites were formed in a stress field which was homogeneous on the exposure scale this was followed by the reactivation of pre existing extension fractures as strike slip faults whose activity determined stress perturbations a very heterogeneous stress field was produced leading to the formation of new localized stylolites and extension fractures especially at fault terminations and at oversteps thus the final pattern shows the superimposition of all these structures reactivation of structures was caused by slight temporal changes in the orientation and intensity of the stress field produced by the nearby regional strike slip faults our study suggests that the origin of stress deviations or superimpositions cannot be explained by random measurements of 1 it is essential to be able to synthesize the fault pattern and the stress trajectories which it determines and to do this a very high density or a selection of data from mesoscale structures is needed

geodynamic evolution of the sw europe variscides 1 the early evolution of sw europe variscides started by opening of the rheic ocean at 500 ma splitting avalonia from armorica iberia subduction on the se side of rheic generated the paleotethys back arc basin 430 390 ma splitting armorica from iberia with development of porto tomar ferreira do alentejo ptfa dextral transform defining the boundary between continental armorica and finisterra microplate to the w obduction of paleotethys was followed by armorica iberia collision and emplacement of nw iberian allochthonous units at 390 370 ma whereas toward the west of ptfa there was antithetic ophiolite obduction beja acebuches and rheic ophiolites plus finisterra continental slices on top of ossa morena zone with simultaneous development of eclogites and orogenic magmatism under a flake double wedge tectonic regime continued convergence 370 ma proceeded by intracontinental deformation with progressive tightening of the ibero armorican arc through dextral transpression on the cantabrian indentor from iberia to armorica the proposed model is discussed at the light of the driving mechanism of soft plate tectonics

behavior of gold in the lateritic equatorial environment weathering and surface dispersion of residual gold particles at dondo mobi gabon abstract a supergene gold dispersion halo has developed at dondo mobi southern gabon from the weathering of an auriferous lisvenite under equatorial humid rain forest conditions morphological and chemical studies were performed on gold particles extracted from both fresh and weathered rocks from different parts of the dispersion halo the results demonstrate that the gold particles are residual and are subjected to increasing weathering upward through the profile from the protore to the surface in the central part of the halo and at the surface both laterally upslope and downslope weathering continues downward into the formerly barren saprolites which were derived from proterozoic schist and archean gneiss rim of the halo thus the au content progressively decreases as does the ag content of gold particles with distance from the center of the ore body gold particles subjected to increased weathering are smaller with more rounded shapes and surfaces pitted by dissolution the dispersion pattern is controlled by au dissolution and translocation of residual gold particles these processes involve an autochthonous evolution in the central part of the halo and a para autochthonous evolution at the rim of the halo at dondo mobi chloride and humic substances are the only ligands present in significant concentrations that are capable of complexing au thermodynamic calculations demonstrate that under such acidic conditions ph ranges from 4 to 6 gold stability increases with increasing silver content the dominant au complexes formed have been calculated to be an aurous hydroxichloride complex and an organometallic complex both of which are stable at surficial conditions thus both chemical and translocation processes control the mobility of au and gold particles in equatorial lateritic weathering profiles

petrology and thermal maturity of coals in the jharia basin implications for oil and gas origins abstract coals from the karharbari formation early permian the barakar formation early permian and the raniganj formation late permian of the jharia basin have distinctive petrographic characteristics the karharbari formation coals are dominated by inertinite whereas the barakar formation and the raniganj formation coals are vitrinite dominated the vitrinite and exinite content of the jharia basin coals generally increases towards the upper parts of the sequence coal facies analyses based on petrographic composition that the jharia coals were formed from woody peat facies in a fluvial environment the karharbari coals were formed in a predominantly forest swamp condition whereas the lower barakar coals were formed in mixed facies wet dry conditions the middle and upper barakar and the raniganj coals were formed under wet forest swamp conditions high rank permian coals r v max 0 93 1 27 occur near the surface in the jharia basin comparisons of the vitrinite reflectance versus depth profiles from the jharia basin samples with some known reflectance profiles indicate that 2 5 3 5 km of cover was lost in the jharia basin cover loss values extrapolated from a profile matching method show good correlation with those calculated from model temperatures the thermal history of the jharia basin suggests that the permian sections of the basin suffered a major permian triassic thermal event during this time a tensional tectonic regime probably prevailed in india possibly centred in the jharia basin this probably caused extensive subsidence and consequently a thicker sedimentary sequence was deposited in the jharia basin than in the other gondwana basins of india the early permian barakar formation is late mature to overmature this section has a high potential for oil condensate and gas generation although only condensate and gas are likely to be preserved the late permian raniganj formation is mature and the source potential for hydrocarbon generation of this section is assessed as very good however most structures within the jharia basin are probably fractured

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

the southern iberian shear zone a major boundary in the hercynian folded belt a long ductile shear zone extending across the northern parts of sevilla and huelva provinces southwest spain and very probably stretching further west into portugal is characterized by a conspicuously developed l s fabric and the existence of various mylonitic textures the shear zone closely associated with amphibolites of tholeiitic affinity represents an important oceanic suture of the hercynian belt in europe the sense of displacement inferred from microstructures is consistent with southwest directed upthrusting evolving to a left lateral shearing movement

analysis of fault slip inversions do they constrain stress or strain rate fault slip data commonly are used to infer the orientations and relative magnitudes of either the principal stresses or the principal strain rates which are not necessarily parallel or equal at the local scale of an individual fault the shear plane and slip direction define the orientations of the local principal strain rate axes but not in general the local principal stress axes at a large scale the orientations of p and t axes maxima for sets of fault slip data do not provide accurate inversion solutions for either strain rate or stress the quantitative inversion of such fault slip data however provides direct constraints on the orientations and relative magnitudes of the global principal strain rates to interpret the inversion solution as constraining the global principal stresses requires that 1 the fault slip pattern must have a characteristic symmetry no lower than orthorhombic 2 the material must be mechanically isotropic and 3 there must be a linear constitutive relationship between the global stress and the global strain rate isotropic linear elastic constitutive equations are appropriate to describe the local deformation surrounding an individual slip discontinuity fault slip inversions however constrain the characteristics of a large scale cataclastic flow which is described by constitutive equations that are probably but to an unknown degree anisotropic and nonlinear such material behavior would not strictly satisfy the requirements for the stress interpretation thus at the present state of knowledge fault slip inversion solutions are most reliably interpreted as constraining the principal strain rates

lower eocene alluvial paleosols willwood formation northwest wyoming u s a and their significance for paleoecology paleoclimatology and basin analysis abstract the lower eocene willwood formation of northwest wyoming is a 700 m thick accumulation of alluvial floodplain and channel mudstones and sandstones nearly all of which show paleopedogenic modifications pedogenesis of willwood sandstones is indicated by taproot and vertebrate and invertebrate bioturbation early local cementation by calcium carbonate and thin illuviation cutans on clastic grains pedogenesis in willwood mudstones is indicated by plant bioturbation insect and other invertebrate burrow casts and lebensspuren free iron aluminum and manganese mobilization including hydromorphic gleying sesquioxide and calcareous glaebule formation in lower parts of the solum presence of clay rich and organic carbon rich zones and well differentiated epipedons and albic and spodic horizons probable a horizons are also locally well developed occurrence of variegated paleosol units in thick floodplain mudstone deposits and their association with thin lenticular and unconnected fluvial sandstones in the willwood formation of the central and southeast bighorn basin suggest that these soils formed during times of rapid sediment accumulation the tabular geometry and lateral persistence of soil units as well as the absence of catenization indicate that willwood floodplains were broad and essentially featureless all willwood paleosols were developed on alluvial parent materials and are complex in that b horizons of younger paleosols were commonly superimposed upon and mask properties of suspected a and b horizons of the next older paleosols the soils appear to be wet varieties of the spodosol and entisol groups aquods and ferrods and aquents respectively though thick superposed and less mottled red purple and yellow paleosols resemble some ultisols most willwood paleosols resemble warm temperate to subtropical alluvial soils that form today under alternating wet and dry conditions and or fluctuating water tables the up section decrease in frequency of gley mottles increase in numerical proportion and thickness of red versus orange coloration and increase in abundance of calcrete glaebules indicate better drained soils and probably drier climate in late willwood time this drying is believed to be related to creation of rain shadows and spacing of rainfall but not necessarily decrease in absolute rainfall due to progressive tectonic structural elevation of the mountainous margins of the bighorn basin

a multiscale methodology for the analysis of velocity anisotropy in organic rich shale abstractchanges in the sources of velocity anisotropy and their relative magnitude as maturation progresses in organic rich shale are still incompletely characterized in the rock physics literature as a result of the increasing importance of organic rich shale as unconventional reservoirs a more thorough understanding of the elastic behavior of shale is needed we have formulated a comprehensive multiphysics multiscale experimental methodology for the characterization of the intrinsic syn lithification and extrinsic postlithification factors contributing to velocity anisotropy application of this methodology to unsaturated samples also enabled the characterization of the shale frame for fluid substitution modeling the methodological framework was then tested on a set of five naturally matured organic rich shale samples in this experimental methodology we combined classical rock physics measurements e g ultrasonic velocity and emergent high resolution imaging techniques such as x ray diffra

stratigraphic and biofacies patterns in the middle pennsylvanian magoffin marine unit in the appalachian basin u s a abstract the magoffin marine unit is a middle pennsylvanian age interval of marine strata that directly overlies the taylor copeland and correlative coal zones in the appalachian basin for this study the magoffin was measured described and sampled at 17 localities along a northeast to southwest transect in the center of the middle pennsylvanian outcrop belt in eastern kentucky and west virginia throughout the study area the base of the magoffin is characterized by a thin dark highly fossiliferous limestone with a brachiopod dominated fossil assemblage the limestone base is usually overlain by a fining upward sequence consisting of fossiliferous dark shales or mudstones with mollusk dominated assemblages these dark mudstones include a fissile black shale with a distinctive posidonia fauna deposited over part of the study area the lower fining sequence is overlain by a thicker coarsening sequence bearing brachiopod dominated fossil assemblages the lower beds of the magoffin particularly the basal limestone are persistent and relatively uniform throughout the study area in contrast strata in the upper part of the magoffin sequence show a high degree of geographic variability with localities in the southwestern half of the study area showing two successive thick coarsening upward sequences of strata while those to the northeast record a single thinner coarsening upward sequence the widespread uniform nature of the basal magoffin limestone appears to indicate rapid transgressive flooding of the coal swamp and associated environments accompanied by a hiatus in clastic influx into the magoffin seaway nearshore brachiopod faunas were replaced by deeper water possibly dysaerobic adapted mollusk faunas as transgression progressed culminating in the fissile black shales and monotaxic posidonia fauna deposited beneath a localized pycnocline during maximum transgression the onset of regression is indicated by the reverse of the stratigraphic sequence of faunas observed during transgression and by the return of rapid clastic influx into the basin

comparative petrological analysis between the permian coals of india and western australia paleoenvironments and thermal history abstract permian sequences preserved in western australian basins collie perth and canning and the gondwana basins of india damodar son mahanadi pench kanhan and godavari valley have similar stratigraphic succession faunal and floral assemblages coal types and rank and structure as for coal types petrographic analyses of indian coals indicate that vitrinite liptinite inertinite and mineral matter content ranges from 37 to 56 8 to 14 24 to 35 and 12 to 18 respectively western australian coals show contents of vitrinite liptinite inertinite and mineral matter ranging from 31 to 67 6 to 10 20 to 57 and 6 to 7 respectively as for rank of coal in india high rank coals r v max 0 70 1 67 occur in the damodar valley basin in this basin vertical rank gradients are higher and uplift and removal of cover has occurred to a greater extent than in the other gondwana basins of india some coals from pench kanhan valley basin r v max 0 72 1 02 and son valley basin r v max 0 70 1 10 have high reflectance values coals from other gondwana basins occur at shallow depths and are of sub bituminous rank r v max r v max 0 32 0 47 and canning basins r v max 0 32 0 56 reach a sub bituminous rank and do not vary significantly laterally or with depth in the busselton area of the southern perth basin r v max ranges from 0 54 to 0 63 coals examined from the beagle ridge area of the perth basin have a high rank r v max 1 compared to other coals in the basin thus the type and rank of the permian coals indicate a similar depositional and thermal histories for the basin studied in india and western australia this is consistent with the view that india and western australia were in close proximity before the break up of gondwanaland

petrographic examination of low rank coals from saskatchewan and british columbia canada including reflected and fluorescent light microscopy sem and laboratory oxidation procedures the response to oxidation of eight coals of lignite and subbituminous rank from saskatchewan and hat creek british columbia was studied by means of maceral distribution fluorescence and scanning electron microscopy sem the oxidizing agent used was schulze s solution with some modification of reaction time from that normally employed in palynological maceration these eight samples were chosen to represent different macroscopically described lithotypes maceral analysis indicates that the huminite macerals behave differently when oxidized densinite seems to be the most susceptible to destruction along with gelinite humotelinite eu ulminite and texto ulminite is more resistant and in four of the eight samples shows a slight increase in concentration oxidation increases the relative content of liptinite along with some of the inertinite macerals fusinite and semifusinite among the liptinite macerals resinite appears to be preferentially concentrated suggesting that the modified oxidation pr

petrographic characteristics and palaeoenvironment of the permian coal resources of the barapukuria and dighipara basins bangladesh abstract twenty seven coal samples from the barapukuria and dighipara coal basins of bangladesh were analysed for their maceral content petrographic characteristics and vitrinite reflectance the most predominant maceral was the inertinite group mean 40 followed by vitrinite mean 31 and liptinite mean 22 with considerable amounts of mineral matter mean 7 semifusinite fusinite and inertodetrinite were the most common macerals of the inertinite group collotelinite collodetrinite and vitrodetrinite were the most frequently found macerals of the vitrinite group while sporinite and cutinite were the most common in the liptinite group clay minerals occurred in higher concentrations than other minerals the measured vitrinite reflectance values ro ranged from 0 71 to 0 80 indicating a high volatile bituminous b ranking facies modelling using maceral composition and maceral indices suggested an environment of forest swamps with alternating oxic anoxic depositional conditions microlithotype dependent depositional modelling indicated evolution in limno telmatic zones under fluvio lacustrine control accompanied by the development of upper to lower deltaic plain conditions a terrestrial origin with dry forest to piedmont plain conditions was suggested by the gelification index gi and tissue preservation index tpi the lateral variation of the measured tpi values indicated an increase in the rate of basin subsidence a cross plot of the ground water index gwi vs the vegetation index vi suggested mires under ombotrophic to mesotrophic hydrogeological conditions containing herbaceous plants

response of the san andreas fault to the 1983 coalinga nunez earthquakes an application of interaction based probabilities for parkfield 1 the parkfield cholame section of the san andreas fault site of an unfulfilled earthquake forecast in 1985 is the best monitored section of the world s most closely watched fault in 1983 the m 6 5 coalinga and m 6 0 nunez events struck 25 km northeast of parkfield seismicity rates climbed for 18 months along the creeping section of the san andreas north of parkfield and dropped for 6 years along the locked section to the south right lateral creep also slowed or reversed from parkfield south here we calculate that the coalinga sequence increased the shear and coulomb stress on the creeping section causing the rate of small shocks to rise until the added stress was shed by additional slip however the 1983 events decreased the shear and coulomb stress on the parkfield segment causing surface creep and seismicity rates to drop we use these observations to cast the likelihood of a parkfield earthquake into an interaction based probability which includes both the renewal of stress following the 1966 parkfield earthquake and the stress transfer from the 1983 coalinga events we calculate that the 1983 shocks dropped the 10 year probability of a m 6 parkfield earthquake by 22 from 54 22 to 42 23 and that the probability did not recover until about 1991 when seismicity and creep resumed our analysis may thus explain why the parkfield earthquake did not strike in the 1980s but not why it was absent in the 1990s we calculate a 58 17 probability of a m 6 parkfield earthquake during 2001 2011 index terms 7223 seismology seismic hazard assessment and prediction 7230 seismology seismicity and seismotectonics 7260 seismology theory and modeling keywords coalinga earthquake parkfield stress change earthquake probability seismicity rate

paleoclimate controls on late paleozoic sedimentation and peat formation in the central appalachian basin u s a abstract in the central appalachian basin at least two major climate changes affected sedimentation during the late paleozoic stratigraphically these two changes are indicated by the distribution of coal beds the variation in coal quality and the variation in rock lithologies in latest mississippian or earliest pennsylvanian time the climate changed from dry seasonal tropical to ever wet equable tropical the equable climate prevailed into the middle pennsylvanian influencing the morphology and geochemistry in peat forming environments many of the peat deposits which formed under the equable climate were probably domed raised bogs low concentrations of dissolved solids in peat formation water resulted in low buffering capacity organic acids caused acidic ph another climate change occurred in late middle pennsylvanian time when evapopation periodically exceeded rainfall resulting in an increase of both dissolved solids and ph 4 to 7 in surface and near surface water throughout the remainder of the pennsylvanian the surfaces of peat deposits were probably planar not domed water in peat forming and other depositional environments became more nearly neutral the coal beds derived from these peats are highly variable in both ash and sulfur contents drier or more seasonal climates are also indicated by sequences of 1 calcareous sandstone and shale 2 nonmarine limestone that shows shallow water and subaerial exposure features and 3 calcareous paleosols that have caliche characteristics our data and observations indicate that physical depositional environment models for the origin of coal do not adequately explain variations in mineral matter content and composition in commercial quality coal beds in the central appalachian basin stratigraphic variation in mineral matter in coal beds and in syngenetic and early diagenetic minerals in rocks associated with the coal beds appears to be better explained by changes in geochemical conditions of nonmarine sedimentation paleoclimate was a principle control on these geochemical conditions

fluvial architecture of early permian barakar rocks of korba gondwana basin eastern central india abstract the early permian barakar formation of the korba basin represents repeated deposition of fining upward sequences of coarse to medium grained sandstone fine grained sandstone shale shale and coal the sandstones are channel sheet like multistory and profusely cross bedded the shale beds are lens as well sheet like and laminated coal facies is thin to moderately thick and shows splitting paleocurrent analysis suggests a northwesterly paleoslope during barakar sedimentation however the deflection of paleoslope towards northeast in the eastern part of the basin supports the existence of a watershed in the depositional area the barakar paleochannel were 4 05 m deep and 176 m wide single channel with an average sinuosity of 1 27 the average flow velocity and sediment load during flood stage are in the order of 1 77 m s and 4 15 these results indicate bed load braided to mixed load nature of the barakar streams of the korba basin the study suggests that the early permian braided barakar streams deposited the coal measure sequence subsequent to deglaciation in a northwesterly slopping paleovalley the basin floor was highly uneven marked by the presence of a basement high in the northwestern part that bifurcates the paleostreams into northwestern and northeastern branches

effect of igneous intrusive on coal microconstituents study from an indian gondwana coalfield abstract petrological and palynological analyses of coals from two bore holes intruded by an igneous body dolerite dyke reveal characteristic changes due to thermal alteration the unaffected coals are high volatile bituminous rr 0 50 0 61 the coals recovered from samples located close to the dyke had vitrinite with devolatization microvacuoles higher reflectance ranging from 0 9 to 3 0 and liptinite with none to very low fluorescence there is an increasing trend in reflectance and a decreasing trend in fluorescence in the samples occurring closer to the dyke presence of injected mineral matter and pyrite in the macerals further indicate the impact of thermal metamorphism on the coals occurring near the igneous body the palynological investigation of unaffected coals shows the presence of a number of well identified spores and pollen however very few palynomorphs could be recovered from coals located close to the intrusive as the pollen spores were found to be charred beyond recognition

maceral distribution in garumnian coals and palaeoenvironmental implications in the central pyrenees spain abstract the organic content of garumnian coals in the central pyrenees of spain is heterogeneous and is formed of plant fragments with the fossil remains of botanic structures and secondary products resulting from thermal and biochemical transformation of macerals the maceral composition of the three areas studied berga tremp and ager is similar the berga and tremp zones include an upward decrease in organic materials and the top sequence is significantly richer in inorganic sediments in contrast in the ager zone only one level with organic matter is present the organic matter of the tremp formation is humic and five resinite groups have also been characterized the mineral phases determined mainly carbonates appear closely associated with macerals infilling cell lumens or replacing cell walls and in layers within the organic matter the maturity and source rock potential of the organic rich beds were investigated using reflected light and fluorescence microscopy the results are compared with other maturity parameters rock eval calorific value and diagenetic mineral matter the vitrinite reflectance r o 0 35 0 45 and the maximum temperature 430 c are low and homogeneous in the different areas these values indicate that the rank of the samples corresponds to an immature diagenetic state close to the lower oil window and allows classification of this coal as subbituminous the relationship between inorganic and organic phases indicates low grade transformation as a consequence of a low lithostatic pressure the macerals indicate that the coal forming peat was deposited in a predominantly forest moor swamp environment the liptinite assemblage suggests a subtropical and damp dlimate during peat deposition the amount of organic matter decreases upwards within the sedimentary sequences analyzed palaeoenvironments were similar in the three areas which could originally have been part of the same basin

stress distribution and failure in anisotropic rock near a bend on a weak fault large transform faults thin skinned thrust faults and listric normal faults often contain restraining and releasing bends that can alter the state of stress in the adjacent crust during faulting episodes crustal rock commonly has anisotropic mechanical properties due to the presence of sedimentary layering subsidiary fractures and faults schistosity or other foliation we present an analytical solution for the stress distribution in anisotropic rock produced by sliding on a wavy frictionless surface the frictionless surface represents the limiting case of a weak fault the fault shape treated is either a sinusoid or a periodic array of isolated restraining and releasing bends the rheological behavior of the rock is that of an incompressible linear viscous fluid with an orthotropic anisotropy characterized by a greater viscosity for shortening and extension than for shear in the principal directions of anisotropy our results illustrate that stress and flow associated with a bend in a fault will extend to much greater distances from the fault when the medium is anisotropic the magnitude of the stress perturbation increases with degree of anisotropy and decreases with radius of curvature of the fault surface principal stress directions tend to align parallel to the principal directions of anisotropy except in the immediate region of the fault bend mean stress and maximum shear stress magnitudes vary along the fault in a cellular manner with multiple maxima near a bend stress concentrations emanate from the bend and are elongate in directions parallel to the principal directions of anisotropy for isotropic rock locations and orientations of shear failure near restraining bends are distinctly different from those near releasing bends in contrast with application of an anisotropic failure criterion as the magnitude of anisotropy increases the patterns of shear failure at a restraining and a releasing bend become increasingly similar the model may help explain field observations from dip slip and strike slip regimes that indicate a complex stress history and local stress reorientation adjacent to a bend in a fault

crustal structure of the transpressional variscan orogen of sw iberia sw iberia deep seismic reflection profile iberseis 1 iberseis a 303 km long 20 s deep seismic reflection profile was acquired across the variscan belt in sw iberian peninsula the acquisition parameters were designed to obtain a high resolution crustal scale image of this orogen the seismic profile samples three major tectonic terranes the south portuguese zone the ossa morena zone and the central iberian zone which were accreted in late paleozoic times these terranes show a distinctive seismic signature as do the sutures separating them late strike slip movements through crustal wedges are apparent in the seismic image and have strongly modified the geometry of sutures the upper crust appears to be decoupled from the lower crust all along the seismic line but some deformation has been accommodated at deeper levels a sill like structure is imaged in the middle crust as a 1 2 s thick and 175 km long high amplitude conspicuous reflective band it is interpreted as a great intrusion of mafic magma in a midcrustal decollement taking into account surface geological data and the revealed crustal architecture a tectonic evolution is proposed for sw iberia which includes transpressional collision interacting during early carboniferous with a mantle plume the moho can be identified along the entire transect as subhorizontal and located at 10 to 11 s indicating a 30 35 km average crustal thickness its seismic signature changes laterally being very reflective beneath the south portuguese zone and the central iberian zone but discontinuous and diffuse below the ossa morena zone

comparison of the petrography palynology and paleobotany of the stockton coal bed west virginia and implications for paleoenvironmental interpretations abstract the stockton coal bed middle pennsylvanian is a relatively high ash coal composed primarily of moderately thin banded sparsely thin banded and nonbanded coal splint and cannel coal comparisons of petrographic palynologic and paleobotanic data gathered from the same sample sets from a single column of the stockton coal bed indicate that compositional correspondences among the sets exist regardless of coal type some correspondences are believed to exist because of original plant constituents and others because of the paleoenvironment of peat formation using some combination of these data is critical when interpreting paleoenvironmental conditions because 1 a direct correspondence is lacking between many of the data and 2 each of the three data sets provides a unique and important perspective on the paleomire the stockton paleomire in the area of this study supported a diverse flora that consisted of both small and arboreous lycopsids small ferns and tree ferns calamites cordaites and pteridosperms there appear to have been two successions of lycospora spore dominated vitrinite rich liptinite poor peat formation which were followed by inertinite rich peat formation marked by a tree fern dominant spore assemblage and abundant unidentifiable plant tissues these are interpreted to be two water laden or topogenous peat formational stages followed by slightly domed better drained peat formation

petrology of some permian coals of india abstract in india permian coal deposits constitute approximately 99 of the total coal reserves of the country and occur in the early permian karharbari formation early permian barakar formation and the late permian raniganj formation in the present study petrographic analyses were carried out on coals from the pench kanhan valley son mahanadi valley and damodar valley basins the permian coals of india show a remarkable range in vitrinite content 13 79 seams with low vitrinite content are common the raniganj formation coals contain more vitrinite than the coals of the barakar and karharbari formation exinite liptinite content of many indian coals varies from 2 to 23 sporinite is generally dominant over cutinite and resinite exinite tends to be associated with vitrinite rich coal and most inertiniterich coals have relatively low exinite content inertinite is relatively abundant 10 67 in many permian coals of india and consists mainly of semifusinite inertodetrinite and fusinite coal facies analysis based on petrographic parameters indicate that the indian peats coals were deposited in dry and wet forest swamps a comparison of indian coals with some other coals of permian age from australia and south africa shows broad similarities even though the coals are from different basinal settings this suggests that palaeoclimate and floral assemblages outweighed basinal setting in determining the coal type being deposited in india outcrops of high rank coals r o max 0 85 1 30 are largely restricted to the damodar valley basin in this basin vertical rank gradients are higher and uplift and erosion have occurred to a greater extent than in other gondwana basins of india coals of other gondwana basins occur at shallow depth and are generally subituminous in rank r o max 0 40 0 65 the oil potential of the coals of the barakar and raniganj formations is very good except in the jharia basin in this basin the oil may have been released due to breaching of the structures

immature oil and condensate modification of hydrocarbon generation model for terrestrial organic matter petroleum has been found in canadian frontier basins in reservoirs which have undergone low levels of thermal alteration vitrinite reflectance 0 6 ro paraffin indices stable carbon and hydrogen isotope contents pristane to nc17 ratios and diterpenoid biologic markers have been used to assess the level of maturity of the hydrocarbons in the reservoir independently of the level of maturity of the reservoir itself and of the surrounding shale units in the tertiary of the beaufort mackenzie basin naphthenic oils and condensates have been generated from terrestrially derived organic matter in source rocks juxtaposed with the reservoir at reflectance levels of 0 4 to 0 6 ro however condensates discovered in reservoirs which are th rmally immature on the labrador shelf have undergone extensive vertical migration and can be classed as conventional mature to overmature condensates hydrocarbons discovered in the lower cretaceous of the beaufort mackenzie basin and also those of the scotian shelf are more or less in place in that they are at a level of thermal alteration about equivalent to that of the reservoirs in which they are trapped the source for the early oils and condensates is considered to be resinite occurring dispersed in coal fragments the proportion of resinite liptinite and vitrinite in the organic matter of terrestrial source rocks strongly controls both the level of thermal alteration necessary for the section to function as an effective source rock and the ultimate product gas oil or condensate which will be generated

poisson s ratio values for rocks abstract compared to other basic mechanical properties of rocks poisson s ratio is an elastic constant of which the significance is generally underrated yet in rock mechanics there is a considerable number of diverse areas which require a prior knowledge or estimation of the value of poisson s ratio this paper examines the values and applications of poisson s ratio in rock mechanics following an historical account of the initial controversy whether it was a material constant or not the effects of poisson s ratio in the elastic deformation of materials intact rocks and rock masses are briefly reviewed also the reported values of poisson s ratio for some elements materials and minerals are compiled while typical ranges of values are presented for some rocks and granular soils finally poisson s ratio classifications are recommended for isotropic intact rocks

stress perturbations registered by jointing near strike slip normal and reverse faults examples from the ebro basin spain stress perturbation patterns created by coeval and preexisting fault planes are characterized by means of detailed mapping and analysis of joint sets in miocene carbonates of the tudela area strike and spacing of the pervasive n s joint set have been specially surveyed for this purpose their spatial variations have been analyzed and interpreted in the light of different theoretical models proposed by other authors perturbations inferred near strike slip faults correspond to the classical examples related to compressional and extensional fault tips a normal fault striking oblique to the horizontal stress axes deflects the latter toward making 2 and 3 trajectories parallel and perpendicular respectively to the fault strike while causing an abrupt stress release within the footwall near a reverse fault with a small dextral component the deflection of 1 trajectories is gentle but a significant increase of differential stress occurs in the hanging wall

changing patterns of pennsylvanian coal swamp vegetation and implications of climatic control on coal occurrence abstract improved regional and interregional stratigraphic correlations of pennsylvanian strata permit comparisons of vegetational changes in euramerican coal swamps the coal swamp vegetation is known directly from in situ coal ball peat deposits from more than 65 coals in the united states and europe interpretations of coal swamp floras on the basis of coal ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps changes in composition of pennsylvanian coal swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate paleobotany and paleogeography of the euramerican province indicate a moist tropical paleoclimate rainfall runoff and evapotranspiration were the variable climatic controls in the distribution of coal swamp vegetation peat accumulation and coal resources in relative terms of climatic wetness the pennsylvanian period is divisible into five intervals which include two relatively drier intervals that developed during the lower middle and middle upper pennsylvanian transitions the climate during early pennsylvanian time was moderately wet and the median in moisture availability early middle pennsylvanian was drier probably seasonally dry wet late middle pennsylvanian was the wettest in the midcontinent early late pennsylvanian was the driest and late late pennsylvanian was probably the wettest in the dunkard basin the five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation regional differences in basinal geology and climate were significant variables but the synchronous control of paleoclimate was of primary importance

effects of thermal maturity on biomarker distributions in gondwana coals from the satpura and damodar valley basins india abstract organic geochemistry of gondwana coals especially the distribution of molecular fossils or biomarkers is not well constrained throughout the world in this study we have therefore evaluated biomarker signatures along with bulk organic matter and petrographic characteristics in coal samples collected from two gondwana basins in india satpura basin kanhan coalfield and damodar valley basin jharia coalfield from both coalfields the samples were collected from the lower permian barakar formation which is one of the major coal bearing strata in india a significant variation in thermal maturity levels in the samples is indicated by rock eval pyrolysis and petrographic analysis with the kanhan samples generally belonging to immature to early mature stage while the jharia samples display characteristics of overmature coals this variation in the thermal maturity strongly affects the biomarker distributions especially the terpenoids hopanes and steranes were considerably degraded due to thermal maturation and were below detection limit in the overmature samples presence of aliphatic diterpanes ent 16 h kaurane 16 h phyllocladane as well as aromatic diterpanes retene methylretenes tetrahydroretene simonellite and bisnorsimonellite in low maturity samples indicate terrestrial input possibly from the primitive conifers however the aliphatic and aromatic diterpanes were below detection limit in overmature samples making it difficult to infer their source distributions of polycyclic aromatic hydrocarbons pahs are also controlled by thermal maturity levels as evident from difference in pah ratios in the low and high maturity samples

walchian conifers from the mid late pennsylvanian conemaugh group in the appalachian basin stratigraphic and depositional context and paleoclimatic significance abstract walchian conifers are indicators of seasonally dry habitats of the euramerican subtropics and tropics and are of considerable value in tracking both short term and long term pennsylvanian permian paleoclimatic changes in central pangea walchian conifer macrofossils first appeared in north america during the middle pennsylvanian but are rare in central pangean coal basins until the permian an abrupt climate change occurred near the desmoinesian missourian boundary that was characterized by global warming stronger seasonality and shorter wet phases this change coincided with the regional extinction of most tree lycopsids and the appearance of widespread high chroma calcic vertisols and aridisols only four occurrences of walchia have been reported from the pennsylvanian of the appalachian basin 1 7 11 mine of eastern ohio 2 rennersville in southwest pennsylvania and 3 charleston and 4 cedar run both in southern west virginia this paper uses recently acquired outcrop data to more fully document and reevaluate the depositional and stratigraphic context of the west virginia assemblages and their paleoclimatic and paleogeographic implications the cedar run walchia assemblage occurs in olive mudshale of an abandoned fluvial channel fill 15 8 16 9 m above the base of the ames limestone indicating an early virgilian age it consists of compressions and impressions of branches and branchlets of walchia lepidophylloides cordaites and rare neuropteroid pinnules the channel fill at this location is a component of the grafton sandstone incised valley fill previously described from the study area correlation of paleosol bounded marine cored cyclothems in the study area with their nonmarine cyclothem equivalents at charleston west virginia indicates the walchia previously reported at the mahoning coal horizon occurs between the brush creek and bakerstown coals and is therefore missourian not late desmoinesian and similar to the revised age for the 7 11 mine walchia reported from eastern ohio late pennsylvanian upland or dryland conifer communities were comprised of walchia cordaites and sigillaria which produced a forest with seed ferns as an understory the cedar run assemblage was probably transported into the valley from adjacent well drained coastal plain uplands formed during valley incision and deposited within the early transgressive systems tract it is also possible that walchia expanded into the valleys when drainage became ephemeral during more arid climatic phases the revised correlations of appalachian basin walchia horizons indicate their appearance closely followed rather than predated the abrupt climate change and extinctions at the desmoinesian missourian boundary

characteristics of upper cretaceous coals from enugu nigeria related to bitumen generation and mobilization abstract a set of nine upper cretaceous coals of sub bituminous rank were studied petrographically and geochemically the coals contain considerable amounts of various liptinites as well as fluorescent vitrinite some bitumen has been generated and mobilized in these low rank coals as evident by the presence of exsudatinite nevertheless no hydrocarbons have been expelled as the amount of bitumen generated is not considered to be sufficient to overcome the threshold saturation of the coals

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

tectonometamorphic evolution of the aracena metamorphic belt sw spain resulting from ridge trench interaction during variscan plate convergence 1 the aracena metamorphic belt is a high temperature low pressure ht lp band located at the southern end of the european variscan chain it marks a suture between armorica and avalonia this belt is characterized by 1 the presence of mid ocean ridge basalt derived metabasites that were affected by an inverted ht lp metamorphism related to sw verging thrusting whose thermal peak diachronously migrated eastward 2 the occurrence of a ht lp metamorphism related to an extensional event affecting continental rocks belonging to the ossa morena zone with peak temperatures that are 150 c higher than that recorded in the oceanic metabasites and 3 the presence of near trench magmatism with high mg andesite composition these and other characteristics can be interpreted in terms of a ridge trench trench triple junction that migrated along the armorican margin during variscan oblique convergence

development of low ash planar peat swamps in an alluvial plain setting the no 5 block beds westphalian d of southern west virginia abstract coals from the no 5 block coal beds westphalian d of the central appalachian basin are noted for their blocky dull character and their low ash and low sulfur content the beds are multiple benched with rock partings separating benches individual benches have limited lateral extent and where thick are dominated by bright high ash coal at the base and dull low ash coal in the upper parts the duller coals contain more exinite group and inertinite group macerals than the brighter coals these coal beds are encased in sandstone units dominated by fining upward sequences the overall depositional setting is an alluvial plain environment with northwest flowing channels spaced approximately 20 km apart the channels were flanked by clastic swamps about 7 km wide low ash peat accum lated in areas of the flood plain most distant from the channels these peat accumulating swamps were about 8 km across in a few instances low frequency flood events introduced fine siliciclastic sediment into the peat swamps depositing a thin layer of sediment on top of the peat this sediment layer is thicker where the underlying coal is the thickest these thick coal areas are topographically lower than surrounding coal areas this relationship between coal thickness parting thickness and topography indicates that these peat swamps were planar at the time of deposition individual coal benches contain abundant preserved cellular tissue telocollinite semifusinite and fusinite at most locations suggesting that robust vegetation was widespread in the swamps and that the morpholo y was planar the high concentrations of exinite group an inertinite group macerals in the upper parts of benches resulted from selective decomposition and oxidation of the peat in subaerial and aquatic planar swamp environments

using stress deflections to identify slip events in fault systems abstract a new approach for identifying past slip events in strike slip fault systems without geological markers is presented a 2 d distinct element modeling code is used to simulate the stress distribution around a strike slip fault zone after a major slip event mature and immature fault zones are investigated slip on the fault is responsible for stress rotations near the active fault strand series of experiments reveal that the stress deflections are qualitatively the same whatever the fault strike fault friction and far field differential stresses for a left lateral fault stresses are rotated clockwise in the two compressive quadrants near the fault tips and counterclockwise in the two extensive quadrants the stress field signature of a slip event thus highlights the extent of the active fault strand conversely the reconstruction of paleostress fields through inversion of minor striated faults that commonly follow slip on the master fault and the analysis of their deflections allow recognition of the fault strands that slipped in a close or remote past application to the left lateral pontarlier fault zone in the jura fold and thrust belt france late cenozoic in age shows that the fault activity has migrated northward in agreement with the in sequence development of the mountain belt

correlation between seismic anisotropy and major geological structures in sw iberia a case study on continental lithosphere deformation in this paper we postulate a correlation between the lithospheric structure and seismic anisotropy inferred from geophysical data and the major structures and tectonic history past tectonothermal features of the outcropping basement rocks in sw iberia oblique plate convergence orogenesis and terrane accretion have been documented for pre mesozoic times in this area however the deviations and areal variations observed between the azimuthal anisotropy of seismic waves and the structural trends of the accessible crust indicate that the tectonic model of orogen parallel lithospheric deformation does not appear to succeed in relating hercynian surface geology and the structural geology of the subcontinental lithospheric mantle the model of polyorogenic lithosphere deformation proposed accounts for this divergence and is supported from additional perspectives including the manifestation of thermal effects induced in the crust by lithospheric mantle shear zones the incidence of crust mantle coupling and or decoupling and the scales of subcrustal heterogeneity

chemical characteristics mineralogical composition and rank of high sulphur coking coals of middle miocene age in the gokler coal field gediz turkey

pennsylvanian deposystems and paleoclimates of the appalachians abstract central appalachian basin rocks indicate major changes in source areas base level and climate for late mississipian through late pennsylvanian time through time dominant source areas change from craton and northeastern orogen to southeastern orogenic mountains the mississipian pennsylvanian uncomformity correlates with a worldwide eustatic event early pennsylvanian rocks contrast markedly with underlying mississippian mauch chunk redbeds in composition and texture yet the source areas and alluvial plain setting were similar seas transgressed northeastward during middle and earliest late pennsylvanian time along axes of the pocahontas and dunkard basins while fluvial dominant deltas prograded northwestward this progradation 1 progressively extended the coastal plain 2 provided coastal swamp environments for peat accumulation and 3 eventually cut off the narrow seaway of dunkard basin from the central interior by late pennsylvanian and transformed it into a large shallow freshwater lake redbeds calcium carbonate concretions and gilgai paleosol structures of late mississippian and late pennsylvanian rocks suggest seasonally dry tropical climate whereas the lithologies of the earlier pennsylvanian rocks are indications of everwet tropical climates with their quartz rich fluvial sandstones high quality coals and aluminum rich clay deposits streams change from predominantly bedload to suspended load generally from early to late pennsylvanian in response to changes in paleoslope gradient distance from source area unvegetated highland and change from everwet to intermittently dry tropical climate greater dryness is suggested for increased alkaline conditions observed in paleosols carbonates and coal beds of late pennsylvanian time but sufficiently wet to prevent evaporite deposition

delineation of the distinctive nature of tertiary coal beds abstract floral character in mires has changed progressively through time in the carboniferous pteridophytes sphenophytes and lycophytes were dominant but by the permian gymnosperms were an important component of mire flora during the early mesozoic gymnosperms remained the characteristic mire vegetation together with pteridophytes and conifers became dominant during the jurassic cretaceous and paleocene vegetation are similar with taxodiaceous flora being important in mire vegetation from the eocene onwards however angiosperms were increasingly dominant in mire communities and in the miocene herbaceous vegetation began to play a significant role together with these changes in floral character at least three aspects of coal character also appear to vary sequentially with time and are distinctive in the tertiary 1 proportions and thickness of vitrain banding 2 coal bed thickness and 3 proportions of carbonised material a compilation has been made of data from the coal literature comparing older coals with those of the tertiary in order to give a perspective in which to examine tertiary coals it was found that only tertiary coals contain significant proportions of coal devoid of vitrain bands in addition tertiary coals are the thickest recorded coal beds and generally contain low percentages of carbonised material many less than 5 as compared to older coals it is interesting to note that paleocene coal beds are similar to cretaceous coals in that they tend to be thinner and contain higher proportions of carbonised material than do younger tertiary coals the absence of vitrain bands in some tertiary coal beds is thought to result from the floras dominated by angiosperms which are relatively easily degraded as compared to gymnosperms the thickness of tertiary coals may be related to an increase in biomass production from the carboniferous through to the tertiary as plants made less investment in producing lignin an energy intensive process in addition with less lignin in plants easier degradation of biomass may have facilitated nutrient recycling which in turn led to greater biomass production increased biomass production may have also diluted the carbonised material present in some tertiary peats leading to lower proportions in the coal another possible cause of decreased carbonised components in tertiary coal is that decreasing lignin content resulted in decreased charring during fires as lignin is particularly prone to charring a third possibility is that the carbonised component of peat may be concentrated during coalification so that tertiary coals generally of lower rank than mesozoic or paleozoic coals contain a smaller fraction of carbonised plant material it is not at present clear which of these mechanisms may have affected carbonised material in peat and coal but it is clear that lignin type and content has had an important role in determining peat and coal character since the paleozoic

authigenic quartz in the upper freeport coal bed west central pennsylvania cathodoluminescence petrography was used to examine quartz grains contained in facies of the upper freeport coal bed middle pennsylvanian of west central pennsylvania samples included ash concentrates polished blocks of different lithotypes and standard petrographic pellets of specific gravity separates of facies channel samples more than 80 of the quartz in mineral and vitrain rich bands in the polished blocks of the upper freeport coal bed do not exhibit cathodoluminescence in specific gravity separates of the coal 100 of the quartz examined in the lightest gravity separates did not luminesce in the heaviest gravity separates which included shale parting material 60 of the quartz did not luminesce in contrast in a sample of shale directly overlying the coal bed more than 90 of the quartz luminesced on the basis of these cathodoluminescence data and other published data quartz in the upper freeport coal bed is interpreted to be authigenic in origin the authigenic quartz grains are postulated to have been derived from phytoclasts

petrographic and chemical properties of carboniferous resinite from the herrin no 6 coal seam abstract resinite is a naturally occurring substance found in coal and derived from original plant resins it is ubiquitous in north american coals and comprises 1 to 4 by volume of most illinois coals it has been commercially exploited in the western usa for use in adhesives varnishes and thermal setting inks the major objectives of this study were 1 to separate resinite macerals from the herrin no 6 coal seam and to carefully verify by petrographic and fluorescence microspectrophotometric methods that the separated material was indeed resinite 2 to characterize the chemical composition of the separated resinite by py gc ms techniques and 3 to confirm the earlier results that show that this carboniferous resinite was a much different chemical substance than the cretaceous and younger resinites an additional objective was to compare the separated resinite to the resinite being commercially exploited in the western usa high purity fractions of resinite concentrates were separated from the herrin no 6 coal by a combination of density gradient separation and sink float techniques the chemical structure of the resinite concentrate indicated by the py gc ms analysis is that of a straight chain aliphatic polymer much like common polyethylene this result confirms the earlier work of nip et al nip m de leeuw j w crelling j c 1992 chemical structure of bituminous coal and its constituent maceral fractions as revealed by flash pyrolysis energy fuels 6 125 136 the assumption that the resinites in the illinois basin were similar in nature to the commercial resinites of the younger coals of the western usa appears invalid in the case of the resinite in the herrin no 6 coal although the botanical function of the carboniferous resinite is at present unclear it is clear that the cutinite and resinite precursors had not yet evolved to the point where they had differentiated into significantly different chemical compounds

organic petrology of fukang permian lucaogou formation oil shales at the northern foot of bogda mountain junggar basin china abstract the fukang oil shale zone located in the northern bogda mountain on the southern margin of the junggar basin was deposited in a deep lacustrine environment permian lucaogou formation shale samples collected from six measured outcrop profiles were characterized using organic petrographic and geochemical techniques the macerals can be divided into four groups bituminite liptinite vitrinite and fusinite oil shales are different from coal by their lower content of vitrinite and fusinite but generally high content of bituminite and liptinite all samples containing sufficient hydrogen rich organic matter types i and ii are considered to have a high potential for oil generation the organic matter was deposited in a clastic algal dominated deep water environment and it mainly consists of unstructured bituminite and mineral bituminous groundmass the oil shales with a sapropelitic constituent content lower than 5 5 to 15 15 to 25 and over 25 correspond to non oil shale low quality medium quality and high quality oil shales in industrial grade respectively approximately 65 of the samples belong to sapropel containing shales with an oil yield between 3 5 and 10 which are low quality and medium quality oil shales the total maceral content can be used as an auxiliary index to classify the industrial grade of oil shales oil yields of 3 5 5 and 10 correspond to total organic matter contents of 7 8 9 8 and 17 5 respectively

a reappraisal of the structure of the spanish segment of the iberian pyrite belt the major structural features of the iberian pyrite belt are described in terms of geometry deformation mechanisms scale timing kinematics and the mutual relationships among the various architectural elements the result of such an analysis allows this zone to be considered as a s verging thin skinned fold and thrust belt propagating southwards over a mid crustal basal detachment this was the response in the footwall of the suture to the major phase of hercynian oblique collision between the south portuguese plate and the ossa morena zone of the iberian autochthon this thin skinned event inverted a previous extensional structure acquired during the initial stages of the collisional process and intimately linked to the formation of the ore deposits that make this region a world class metallogenic province

characterization of stress perturbations near major fault zones insights from 2 d distinct element numerical modelling and field studies jura mountains abstract we consider and discuss the presence of discontinuities in the crust as a major source of stress perturbations based on 2 d distinct element modelling we reconstruct the local stress field around a vertical discontinuity in various geological contexts the resulting stress distribution reveals that major directional stress changes occur near the tips of the discontinuity so that stress deviations can reach values as large as 50 we establish simple relationships controlling stress changes around a pre existing fault zone as a function of 1 the remote differential stress magnitude 1 3 2 the friction coefficient on the discontinuity and 3 the strike of the discontinuity relative to the far field stress as a geological example we present the morez fault zone in the internal jura paleostress reconstruction in forty two sites indicates that the trends of the mio pliocene compression are n110 on average near the fault whereas they are n130 in the surrounding areas a comparison between the results of the tectonic study and those of theoretical modelling suggests that the 20 counterclockwise deviation is directly related to the reactivation of this large weak zone we thus evaluate the role of mechanical decoupling along pre existing zones of weakness especially with consideration to the accommodation of the alpine deformation in the jura belt

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

resino inertinites of indian permian coals their origin genesis and classification abstract variously shaped discrete bodies with reflectance higher than the associated vitrinite occur in permian coals in india australia and africa and the carboniferous coals of the united states canada and europe these bodies have been variously named by different authors in the present paper they are described as resino inertinites as suggested by lyons et al 1982 based on available information and our observations on carboniferous and permian coals it is presumed that resino inertinites were formed mainly from the resinous resinite and to some extent from the phlobaphinitic or corpocollinitic substances various morphological patterns developed on resino inertinites have been interpreted to be governed by the chemical composition of their precursors and the degree of oxidation or fusinization during coalification influences of other vvariables viz paleoenvironmental paleodepositional tectonic set up etc on resino inertinites are not clearly recognizable probably because all the previous effects were masked by subsequent fusinization different morphological features of resino inertinites associated with early diagenetic and secondary mineralization have caused much confusion in their proper identification and classification in order to resolve this problem an attempt has been made to ascertain the source of resins in indian permian coals and their subsequent mode of transformation into resino inertinites during coalification further by critically evaluating morphological features of resino inertinites and keeping the chemical nature of their precursors in view a classification scheme has been proposed categorizing them into 3 types the classification proposed may prove as a useful means for coal seam correlation

changes in dominance patterns in upper carboniferous plant fossil assemblages upper carboniferous pennsylvanian terrestrial clastic rocks from north america and europe contain compression impression plant fossil assemblages that represent the remains of plant communities that grew on floodplains levees and other clastic facies of fluvial and deltaic lowlands quantitative analysis of 66 plant fossil assemblages spanning the entire late carboniferous demonstrates that before the middle of the westphalian d stage the majority of plant fossil assemblages are dominated by pteridosperms and sphenopsids lycopods and cordaites dominate only a few assemblages counted ferns do not dominate any assemblages these findings contrast sharply with the dominance of lycopods reported by others from coal swamps of the same time interval above the middle of the westphalian d however one third of the compression impression assemblages counted are dominated by ferns the change in dominance pattern in compression impression plant fossil assemblages occurs half a stage earlier than the previously reported change from lycopod dominated to fern dominated assemblages at the westphalian stephanian boundary in coal swamps a trend toward dryer climate during westphalian d apparently influenced plants growing on better drained alluvial soils earlier than those growing on water logged soils of contemporaneous coal swamps

cordaiteans in paleotropical wetlands an ecological re evaluation abstract cordaiteans in cordaite dominated permineralized peat from pennsylvanian coals in iowa have been reconstructed as mangroves using root anatomy peat taphonomy and geochemical data macrofloral palynofloral and conodont biostratigraphy indicate that these peats come from the latest atokan blackoak coal and earliest desmoinesian cliffland coal mid moscovian both in the kalo formation thus their depositional setting can be used to evaluate the mangrove hypothesis in recent mires thick mangrove peats have accumulated in tropical to subtropical carbonate systems in contrast thick tropical freshwater peats have accumulated in siliclastic systems kalo formation coals which we interpret as freshwater deposits formed in siliciclastic depositional settings similar to those of modern tropical freshwater peat and to other pennsylvanian coals in north america interpreted as freshwater deposits in the late atokan and earliest desmoinesian mid moscovian cordaiteans and tree ferns predominated in the western interior and illinois basins lycopsids and cordaiteans predominated in the appalachian and donets basins the scarcity of lycopsid only mires in north america during the late atokan earliest desmoinesian mid moscovian suggests drier climates than during the mid to late desmoinesian late moscovian rather than indicating mangrove swamps cordaite dominated peat may indicate climates with a low rain season although most plants in cordaite dominated peat probably grew in freshwater coastal mires in climate zones with seasons of low rain may harbor mangrove taxa the changuinola swamp of panama a modern peat accumulating wetland that has a low rain season is a possible analog of ancient cordaite dominated mires in changuinola most plants require freshwater however mangroves sustained by salt water influx into the swamp grow along the seaward edge and along blackwater creeks the low rain season hypothesis has implications for understanding rainfall amount and continuity during pennsylvanian cyclothem deposition the floral succession in diverse cordaite coals from cordaiteans to tree ferns to lycopsids suggests increasingly wet climate during coal accumulation the position of these coals immediately above the sequence boundary suggests humid climate during early glacial melting for these cyclothems

palaeostress perturbations near the el castillo de las guardas fault sw iberian massif use of stress inversion methods on faults measured at 33 sites located at the northwestern part of the south portuguese zone variscan iberian massif and analysis of the basic dyke attitude at this same region has revealed a prominent perturbation of the stress trajectories around some large crustal scale faults like the el castillo de las guardas fault the results are compared with the predictions of theoretical models of palaeostress deviations near master faults according to this comparison the el castillo de las guardas fault an old structure that probably reversed several times its slip sense can be considered as a sinistral strike slip fault during the moscovian these results also point out the main shortcomings that still hinder a rigorous quantitative use of the theoretical models of stress perturbations around major faults the spatial variation in the parameters governing the brittle behaviour of the continental crust and the possibility of oblique slip along outcrop scale faults in regions subjected to general non plane strain

stratigraphic and interregional changes in pennsylvanian coal swamp vegetation environmental inferences abstract quantitative analysis of pennsylvanian coal swamp vegetation provides a means of inferring organization and structure of communities distribution of these communities further provides inferences about environmental factors including paleoclimate our observations are based on in situ structurally preserved peat deposits in coal ball concretions from 32 coal seams in the eastern one half of the united states and from several seams in western europe and on spore assemblages from more than 150 seams there were three times of particularly significant and nearly synchronous vegetational changes in the midcontinent and appalachian coal regions during the pennsylvanian period each was different in kind and magnitude the first marked changes occurred during the early part of the middle pennsylvanian with the fluctuating decline in the high level of lycopod dominance the abundance of cordaites increased there was a rise in the occurrences of the lycopod herbs to form intercalated marshlands and an overall increase in floral diversity changes ensuing from this time also include shifts in dominant species of lycopod trees and a sustained rise in abundance and diversity of tree fern spores the next significant time of change was during the middle part of the middle pennsylvanian representing both a culmination of earlier trends and expansions of cordaites in the midcontinent where there was a maximum change in species without net loss of diversity tree ferns and medullosan pteridosperms attained subdominant levels of abundance and diverse lycopod species dominated except in the atokan desmoinesian transition of the midcontinent the third and sharpest break occurred near the middle late pennsylvanian boundary when extinctionsof the dominant coal swamp lycopods allowed development of tree fern dominance the late pennsylvanian coal swamps apparently were colonized or recolonized mainly by species from outside coal swamps rather than by the survivor populations of the middle pennsylvanian swamps paralleling the changes in floras through the pennsylvanian are changes in preservational aspects of the peat these include a decline in shoot root ratios from approximately 1 to

final stages of the variscan orogeny at the southern iberian massif lateral extrusion and rotation of continental blocks 1 the southern part of the iberian massif contains one of the sutures of the european variscan belt several systems of faults and dikes appear as a result of a period of brittle deformation during the late stages of the variscan tectonic evolution of this zone a detailed analysis of these structures has been carried out in this work four successive deformation phases have been identified a first strike slip normal faulting stage a transcurrent stage a second strike slip normal faulting stage and finally a thrusting stage the age of these phases vary between around 310 ma and less than 270 ma the computed trajectories of the deformation axes show a progressive anticlockwise rotation of around 90 these data together with the results of previous geological and geophysical studies of this zone and of the variscan belt as a whole lead us to propose a model of tectonic evolution for the last stages of the variscan collision comparison with modern examples of collisional belts and with the results of analog experiments suggests that a promontory of the continental lithosphere of the downgoing plate indented against the active continental margin of the upper plate the indenter suffered an intense deformation in accordance with the predictions of some recent analog models simulating the indentation of a four layer continental lithosphere the variscan and late variscan brittle deformation episodes represent the waning stages of the variscan collision and not an independent tectonic event

petrology palynology and depositional environments of coals of the upper carboniferous barachois group westphalian a and c southwestern newfoundland coal samples from the barachois group of western newfoudland vary in rank from high volatile c to high volatile a the coals are vitrinite rich 70 except some from coal brook that contain substantial quantities of inertinite up to 52 liptinite ranges up to 18 but is a relatively minor component the most abundant constituents amongst the three maceral groups are vitrinite vitrinite a inertinite semifusinite and liptinite sporinite compositional profiles in three of the seams show no clear correlation between maceral group content and stratigraphic position the barachois group coals are relatively high in ash mean 12 8 and sulphur mean 6 9 spore assemblages from coal samples of the barachois group indicate a westphalian a age in the barachois brook and coal brook areas and a westphalian c age along blanche brook barachaois coals are part of a mudstone dominated facies association that developed in an assemblage of floodplain environments plots of tissue preservation gelificat

the variation of cesium and 37 other elements in the sardinian granite batholith and the significance of cesium for granite petrogenesis a suite of granites from the hercynian batholith of sardinia italy was analysed for cesium and 37 other major and trace elements factor analysis was used to identify inter element associations in this set of data cesium is shown to be closely associated with tin lithium and rubidium and less closely with beryllium and thallium but it shows no correlation with any of the major elements the role of crystal fractionation magma mixing and the process of partial melting in the magmatic source region are examined as possible controls of cs distribution the pattern of element associations revealed by factor analysis eliminates crystal fractionation and magma mixing as the main cause of magmatic variation the variation in cs is considered to be primary in origin i e it originated in the magmatic source region the relationship between cs and other elements was mainly determined by the relative proportions of mica and feldspar entering the melt during anatexis

spectral fluorescence analysis of some liptinite macerals from panandhro lignite kutch gujarat india abstract spectrofluorimetric analyses of sporinite alginite and resinite macerals of eocene lignite from the panandhro lignite field indicate that they are distinguishable on the basis of their max and red green quotients sporinite fluorescing with bright yellow colour has an average max at 570 nm with red green quotient q 0 92 alginite botrycoccus with a bright yellow fluorescence colour has a peak average at 540 nm with q 0 71 resinite in the panandhro lignite has been categorized into five types resinite type 1 yellowish green to greenish yellow is characterized by average max at 510 nm with a q value of 0 29 in resinite type 2 bright yellow the average max occurs at 520 nm with q 0 49 resinite type 3 yellowish orange to orange shows a max average at 520 nm with a q value of 0 69 resinite type 4 has been subdivided into sub types a and b based on its mode of occurrence primary and in situ remobilized sub type 4a pale orange has a max average at 590 nm and q 0 99 whereas sub type 4b fluoresces with faint brownish orange to pale brown colours and shows an average max at 610 nm and q 1 43 the average max at 610 nm and q 2 30 with pale yellowish grey orangish brown and brown fluorescence colours characterize resinite type 5 the wavelength of maximum fluorescence intensities and red green quotients of the sporinite and alginite macerals show a very good correspondence with the rank r0 max of the panandhro lignites the spectral parameters of the maceral resinite on the other hand do not show such a relationship with rank resinite types 1 to 3 are primary in origin whereas types 4 and 5 occur both as primary and in situ remobilized resinites none of the resinite types have been observed as crack or fissure fillings the origin of the resinite types is probably related to lignite forming plant communities chiefly angiospermous vegetation as well as pre and post depositional conditions

kinematic analysis of the southern iberian shear zone and tectonic evolution of the acebuches metabasites sw variscan iberian massif 1 the acebuches metabasites constitute a slice of oceanic crust located at the variscan suture between the ossa morena and the south portuguese zones iberian massif the emplacement of the metabasites onto the accretionary prism was associated with the activity of the southern iberian shear zone careful measurements of the fabrics and structures related to this shear zone show consistent kinematic criteria pointing to the presence of a simple shear component with an oblique predominantly left lateral sense of displacement the data are consistent with existing models of triclinic or oblique shear zones considering coeval simple shear and pure shear components these models provide a satisfactory explanation of the observed spatial variations in the foliation lineation and fold hinge data the kinematics of other shear deformations older and younger than the southern iberian shear zone have also been established these results offer new insights into the tectonic evolution of this suture of the variscan belt and show how complex transpressional strains can arise during oblique crustal deformation associated with the motions of tectonic plates

climatically driven cyclicity and peat formation in fluvial setting of the moscovian early kasimovian cracow sandstone series upper silesia poland abstract the approximately 1200 m thick cracow sandstone series middle early late pennsylvanian in the polish part of the upper silesian coal basin consists of 25 70 m thick fining up and laterally widespread fluvial cycles the cycles are marked by alternating sheet like sandstone bodies overlain by much thinner intervals dominated by mudstone and coal these two member cycles record the alternation of a sand dominated fluvial braidplain and floodplain dominated fluvial system with channels confined to narrow belts the lateral persistence internal architecture and isochronous alternations suggest an allogenic origin for the cycles possibly related to climate this interpretation is supported by a three stage evolution of pedogenic processes operating on floodplain deposits beginning with the formation of vertisols followed later by gleying and finally termination by a histosol peat formation such a succession of paleosols indicates a climatic shift from highly seasonal vertisol to humid climate coal with the most seasonal part of the cycle likely represented by the sheet like sandbody the mechanistic link between climate and the cyclic pattern of strata is explained as climatically driven variations in clastic supply which was highest during periods of prominent seasonality short term climatic oscillations generating cyclic patterns in the cracow sandstone series are superimposed on a long term climatic shift towards increased seasonality near the middle late pennsylvanian boundary this is evidenced by the termination of peat formation in the upper silesian basin as well as in some other coeval basins of the equatorial pangea and is interpreted to represent a potentially regional climatic event

maceral distributions in illinois coals and their paleoenvironmental implications abstract for purposes of assessing the maceral distribution of illinois u s a coals analyses were assembled for 326 face channel and drill core samples from 24 coal members of the pennsylvanian system the inertinite content of coals from the missourian and virgilian series averages 16 1 mineral free compared to 9 4 for older coals from the desmoinesian and older series this indicates there was generally a higher state of oxidation in the peat that formed the younger coals this state probably resulted from greater exposure of these peats to weathering as the climate became drier and the water table lower than was the case for the older coals although oxidation during allochthonous deposition of inertinite components is a genetic factor that needs further study to confirm the importance of the climate regional variation of the vitrinite inertinite ratio v i on a mineral and micrinite free basis was observed in the springfield no 5 and herrin no 6 coal members to be related to the geographical position of paleochannel river deposits known to have been contemporaneous with the peats that formed these two coal strata the v i ratio is highest generally 12 27 in samples from areas adjacent to the channels and lower 5 11 some 10 20 km away we interpret the v i ratio to be an inverse index of the degree of oxidation to which the original peat was exposed high v i ratio coal located near the channels probably formed under more anoxic conditions than did the lower v i ratio coal some distance away from the channels the low v i ratio coal probably formed in areas of the peat swamp where the watertable was generally lower than the channel areas

the diversification of paleozoic fire systems and fluctuations in atmospheric oxygen concentration by comparing silurian through end permian 250 million years myr charcoal abundance with contemporaneous macroecological changes in vegetation and climate we aim to demonstrate that long term variations in fire occurrence and fire system diversification are related to fluctuations in late paleozoic atmospheric oxygen concentration charcoal a proxy for fire occurs in the fossil record from the late silurian 420 myr to the present its presence at any interval in the fossil record is already taken to constrain atmospheric oxygen within the range of 13 to 35 the fire window herein we observe that as predicted atmospheric oxygen levels rise from 13 in the late devonian to 30 in the late permian so too fires progressively occur in an increasing diversity of ecosystems sequentially data of note include the occurrence of charcoal in the late silurian early devonian indicating the burning of a diminutive dominantly rhyniophytoid vegetation an apparent paucity of charcoal in the middle to late devonian that coincides with a predicted atmospheric oxygen low and the subsequent diversification of fire systems throughout the remainder of the late paleozoic first fires become widespread during the early mississippian they then become commonplace in mire systems in the middle mississippian in the pennsylvanian they are first recorded in upland settings and finally based on coal petrology become extremely important in many permian mire settings these trends conform well to changes in atmospheric oxygen concentration as predicted by modeling and indicate oxygen levels are a significant control on long term fire occurrence

volatile production during contact metamorphism the role of organic matter in pelites elemental analyses of palaeozoic mudrocks from south cornwall indicate the presence of 0 04 0 74 wt carbon primarily in an elemental and or organic form in addition to 0 04 0 10 wt nitrogen as nh 4 in micas and in organic material both elements are depleted in samples from the lithologically homogeneous mylor slate formation next to the tregonning granite an offshoot of the cornubian batholith the depletions are due to an h 2 o co 2 n 2 ch 4 fluid formed during contact metamorphic devolatilization of the pelitic country rocks fluids of this type have been reported from a number of hercynian sn w provinces and may play an important role in mobilizing metals in pelitic rocks during granite related contact metamorphism and hence in the metallogenic evolution of such regions

the boundary between the ossa morena and southportuguese zones southern iberian massif major suture in the european hercynian chain the ossa morena zone omz and the southportuguese zone spz represent the southernmost domains of the iberian massif european hercynian belt lithostratigraphic petrographic and structural differences exist between both zones the boundary between the omz and the spz is marked by a narrow belt of amphibolites of tholeiitic oceanic affinity bard mmunha et al 1986 and associated serpentinites flaser gabbros pillowed metabasalts castro et al 1987 which are highly sheared along their southern border these beja acebuches ophiolites op cit are exposed for over 200 km in the southernmost part of the omz and the northernmost area of the spz several zones have been distinguished on the basis of structural and lithological criteria the southernmost area of the omz which bounds the acebuches amphibolites is composed of high grade metamorphic rocks and an another important shear zone mark the omz northern boundary the boundary between the omz and the spz is considered to be a suture zone between two continental areas represented by the northern omz and the southern spz sinistral transpression associated with large scale recumbent folds are characteristic of the suture which can be tentatively correlated through the ibero armorican arc with the lizard complex sw england

constraints on the strength of the upper crust from stress inversion of fault slip data the coefficient of friction of small faults in the field are estimated here by stress inversion of fault slip data the small faults that were measured in israel and the grand canyon arizona are considered as representing natural friction experiments the stresses associated with the faulting are determined by a stress inversion method which incorporates the coulomb failure criterion reches 1987 the coefficients of friction determined for 27 fault clusters in limestone sandstone and basalt range from 0 0 to 1 3 with mean value of 0 58 0 37 these values are in general agreement with the friction of 0 6 0 85 determined from laboratory experiments the magnitudes of the calculated principal stresses are compared with in situ stress measurements in similar tectonic environments

deflection of a compressional stress field by large scale basement faults a case study from the tertiary almazan basin spain abstract palaeostresses deduced from brittle mesostructures more than 50 sites and 1500 structures measured in the mesozoic and tertiary rocks of the almazan basin located in the northwestern iberian chain indicate a regional nne sse directed compression that lasted during all the tertiary shortening stage the stress regime corresponding to this compression ranges from thrust to wrench n s directed compression was the responsible for most macrostructures folds and thrusts forming a s vergent system with ne sw to e w and nw se orientations and mesostructures mainly faults stylolytes and impressed pebbles we propose that the stress trajectories are deflected following anderson s model in the western part of the almazan basin by the ne sw striking left lateral strike slip soria fault this basement fault was inherited from the late variscan fracturing stage and controlled the deposition in the mesozoic basins as well as the location of tertiary compressional macrostructures in the eastern border of the almazan basin palaeostress trajectories were deflected both by right lateral strike slip faults and nw se trending thrusts near which the regional n s directed compression becomes perpendicular to them three minor compression directions have also been recorded in several sites ne sw e w and nw se the ne sw directed compression is interpreted as a deviation of the main n s directed compression at a regional scale whereas the nw se directed stress field corresponds to the regional field responsible for the main tertiary shortening stage in the spanish central system the age of compression ranges from eocene to miocene

pyrolysis induced p wave velocity anisotropy in organic rich shales abstractthe sources of elastic anisotropy in organic rich shale and their relative contribution therein remain poorly understood in the rock physics literature given the importance of organic rich shale as source rocks and unconventional reservoirs it is imperative that a thorough understanding of shale rock physics is developed we made a first attempt at establishing cause and effect relationships between geochemical parameters and microstructure rock physics as organic rich shales thermally mature to minimize auxiliary effects e g mineralogical variations among samples we studied the induced evolution of three pairs of vertical and horizontal shale plugs through dry pyrolysis experiments in lieu of traditional samples from a range of in situ thermal maturities the sensitivity of p wave velocity to pressure showed a significant increase post pyrolysis indicating the development of considerable soft porosity e g microcracks time lapse high resolution backscattered electron scanning electron

fluorescence spectral analysis of resinite macerals from coals of the hanna formation wyoming u s a abstract flourescence spectral analysis indicates that resinite macerals from tertiary hanna formation coals hanna coal field southcentral wyoming u s a can be separated into five distinct groups the first resinite group fluoresces a a medium green in blue light its average spectral maximum occurs at or below 440 mm with a red green quotient of 0 22 the second resinite group fluoresces yellow green with an average spectral maximum of 500 nm and a red green quotient of 0 53 the third resinite group displays a yellow fluorescence having an average spectral maximum of 580 nm and a red green quotient of 0 86 the fourth resinite group fluorescence orange brown having an average spectral maximum of 610 nm and a red green quotient of 1 20 these four groups mostly occur as primary globular resinites exhibiting scratches and fractures indicating that they are brittle solid substances primary cell filling and secondary fracture filling resinites also occur in these four groups the fifth group only occurs as a secondary void filling material and lacks evidence of br of brittle properties it fluoresces a reddish brown has a spectral maximum at 690 nm and a red green quotient of 1 54 the fifth group has properties resembling exsudatinite the five resinite groups can be separated on the basis of their nine spectral properties alone without qualitative petrographic interpretation the relative quantities of the five resinite groups vary among hanna formation coals the origins of these five resinite groups are probably related to their botanical properties and pre and post depossitional conditions overall hanna formation resinites have petrographic characteristics similar to other north american resinites however only four resinite groups have been distinguished in in certain coals from utah and new mexico u s a and western canada

petrography of the herrin no 11 coal in western kentucky abstract the herrin no 11 coal in western kentucky is in the upper part of the pennsylvanian des moinesian carbondale formation samples were obtained from 13 mines in kentucky and one mine in illinois in three equal benches from two to three channels for a total of 93 samples the rank of the coal as vitrinite reflectance is high volatile c bituminous in the moorman syncline and high volatile a bituminous in the webster syncline reflectance does not vary between mines in in the moorman syncline the percentage of total vitrinite macerals for each mine is over 85 and the percentage of togal vitrinite plus liptinite maceralsis over 89 average over 90 both on dry mineral free basis the variation of the two maceral percentages is only significant at the betweenbench level the middle bench generally having the lowest vitrinite and vitrinite plus liptinite percentages