palaeoecology of macroneuropteris scheuchzeri and its implications for resolving the paradox of xeromorphic plants in pennsylvanian wetlands abstract the medullosan pteridosperm macroneuropteris scheuchzeri hoffmann cleal shute zodrow was widespread and abundant in the middle to late pennsylvanian forests of tropical pangaea on the basis of its thick cuticles few adaxial stomata sunken stomata and dense trichomes it has been inferred to be a xeromorphic plant here we test that hypothesis by analyzing its facies distribution especially in relation to coals at 273 site collections from 45 stratigraphic horizons accessioned in the smithsonian national museum of natural history washington d c u s a the collections represent mostly par autochthonous assemblages and cover the taxon s complete known temporal range west of the appalachians in west central pangaea chi square analysis of facies occurrence data indicates that m scheuchzeri had a strong preference for mineral enriched wetlands that immediately preceded and followed the development of peat swamps and mires coals particularly during the late middle pennsylvanian late moscovian times coincident with a period of reduced polar ice volume in the late pennsylvanian following an interval of global warming and tropical wetland reorganization palaeoequatorial climate shifted to an overall drier mode this was accompanied by the disappearance of m scheuchzeri from europe and its limitation west of the appalachians to the wettest available habitats on the landscape thus our data falsify the hypothesis that m scheuchzeri was a conventional xerophyte but highlight the paradox of a plant with apparent xeromorphic features confined to a wetland habitat we consider several possible explanations for this association 1 response to nutrient deficiency 2 response to substrate salinity due to growth in coastal mangrove habitats 3 response to the composition of the palaeozoic atmosphere 4 return on investment long leaf lifespan and 5 phylogenetic constraint reflecting ancestral conditions our findings have broader implications for interpreting a wide variety of other pennsylvanian wetland plants which similarly show xermorphic features

near station topographic masses correction for high accuracy gravimetric prospecting the expanding role of gravity prospecting in mineral and hydrocarbon exploration as well as seismic and volcanic risk studies will be related to its ability to provide high resolution anomalies to achieve this goal it is necessary to consider the errors resulting from the topographic corrections in particular near station effects such errors are relevant not only for severe topographies but also for relatively flat surfaces involving microgravity applications and large scale surveys indeed the errors introduced by low resolution digital elevation models can be of the same order of magnitude as the anomalies of interest this basic fact is demonstrated by tests on synthetic models the results of this analysis are summarized in an intuitive graph that can be used to estimate what near station topographic resolution is necessary for a specific survey for the vulcano island test site in southern italy we also compare results obtained using three different representations of the topographic surface with different horizontal resolutions and vertical precisions one from existing photogrammetric data the second from a digitized map and the third from a very high resolution laser scanning system among the three methods laser scanning is shown to obtain the highest resolution topographic reconstructions in the shortest time some weaknesses of the laser scanning methodology are discussed and we suggest ways of overcoming them

kinematics of a major fan like structure in the eastern part of the sveconorwegian orogen baltic shield south central sweden abstract the n s trending so called protogine zone in the baltic shield of south central sweden is usually considered to mark a tectonic boundary between the rocks of the transscandinavian igneous belt tib in the east and the sveconorwegian orogen in the west detailed structural mapping in the karlskoga kristinehamn area has shown that an anastomosing network of ductile deformation zones with generally n s strike extends ca 40 km east of the traditional protogine zone furthermore the western boundary of this ductile deformation and the tib is not constrained in the kristinehamn area reconnaissance studies indicate that they both extend westwards towards the so called mylonite zone it is suggested that the eastern limit of the sveconorwegian orogen is located some 40 km east of the present boundary and that the protogine zone concept is obsolete the term sveconorwegian frontal deformation zone sfdz is proposed as a more appropriate alternative in southern sweden south of lake vattern and to correspond to a younger set of oblique ductile deformation zones with reverse and right lateral components of movement in the easternmost part of the orogen farther to the north ductile deformation zones older than the sfdz in the karlskoga kristinehamn area display a fan like geometry in an e w cross section with steep westerly dips in the eastern part of the section vertical dips farther west and moderate easterly dips in the western part of the section kinematic analysis indicates that dip slip movements predominate with a consistent top to the east sense of movement across the entire fan like structure in their present orientation deformation zones are characterized by reverse movements in the eastern part and normal movements in the western part of the structure between kristinehamn and the mylonite zone the main foliation is gently dipping to subhorizontal indicating that the regional structure is strongly asymmetric and that the fan like structure occurs close to the foreland of the orogen deformation zones are spaced to semi penetrative in the eastern part of the fan like structure whereas the deformation is more or less penetrative and the tib rocks are transformed to orthogneisses west of kristinehamn this east to west increase in bulk strain is in accordance with an increase in syn deformational metamorphic grade across the structure younger ductile deformation zones belonging to the sfdz are responsible for a major change in orientation of the older deformation zones in the easternmost part of the structure the fan like structure is best explained by models involving the interference of two separate tectonic events deformation occurred after 1 57 ga and prior to deposition of neoproterozoic and younger cover sedimentary rocks it is not yet clear whether the initial phase of deformation early sveconorwegian or older was related to the build up of an imbricate thrust stack in a compressional regime as favoured here or to regional e w extension the younger deformation phase was related to rotation of these older structures into the compressional late sveconorwegian sfdz

history of applied coal petrology in the united states iv reflections on the centennial of the introduction of coal petrology to north america abstract reinhardt thiessen introduced a thin section based botanically oriented method of coal petrology to north america in 1920 the nomenclature derived from this system although eventually reconciled with and largely superseded by the european reflected light techniques and nomenclature persisted for decades after thiessen s death in 1938 the research by thiessen and his colleagues at the u s bureau of mines was the foundation of applied coal petrology in the united states with research on the preparation coking and hydrogenation properties of coals thiessen s botanical training enabled him to recognize distinct spores in coals although he did not macerate the samples and he did not provide genus and species names the demonstration that he could use spores to correlate coals through the northern appalachian coal basin provided a foundation for regional stratigraphic palynology homer turner an american geologist and fuel scientist was a pioneer in the petrographic study of anthracite using a method of etching polished blocks of anthracite he developed a parallel approach to reinhardt thiessen s studies of thin sections of bituminous and lower rank coals describing well preserved botanical structures this in turn supported the view that anthracite just had a higher degree of metamorphism than bituminous coals opposed to the older view that anthracite had a different botanical origin in a joint study with the u s bureau of mines turner produced a map of equal volatile matter contours isovol across the pennsylvania anthracite fields he was also a collaborator in a study on the x ray diffraction structure of anthracite presaging better known studies by rosalind franklin and others

paleoecological interpretation of a middle pennsylvanian coal bed in the central appalachian basin u s a abstract at least 180 small spore species assignable to 62 miospore genera have been identified from the middle pennsylvanian hernshaw coal bed in southern west virginia and its stratigraphic equivalent the fire clay coal bed in eastern kentucky the established natural affinities of a majority of these miospore taxa indicate that the hernshaw fire clay peat swamp supported a diverse flora consisting of arborescent and herbaceous lycopods ferns tree like and small varities calamities and cordaites four floral groupings are recognized in the hernshaw fire clay coal bed the inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the phasic floral communities found in modern domed peat systems suggesting that the ancient hernshaw fire clay peat swamp was a domed deposit compositional characteristics petrographic make up ash yield and sulfur content associated with the four groupings are consistent with and support this interpretation where uninterrupted by inorganic partings the hernshaw fire clay coal bed commonly contains basal coal layers dominated by lycospora bearing arborescent lycopods with successive increments showing a progression to a more fern and herbaceous lycopod dominant flora in younger layers these observations are corroborated by petrographic analyses which show the bed to be compositionally stratified increments dominated by lycospora have high vitrinite contents in contrast to increments containing increased percentages of fern and herbaceous lycopod affiliated taxa that are enriched in inertinite macerals the volcanic ash fall preserved as the flint clay parting in the hernshaw fire clay coal bed had a considerable effect on the development of the ancient hernshaw fire clay peat swamp besides interrupting peat formation the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp this disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups notably cordaites and calamites that may have been better adapted to growth on mineral soils these palynologic and petrographic relationships thought to be indicative of a domed peat swamp origin are not confined to the hernshaw fire clay coal bed but appear to be characteristic of many coal beds in the appalachian basin and also of coal beds in other basins

factors controlling the vegetation distribution and coal forming environments in a strike slip basin the pennsylvanian penarroya belmez espiel basin southern spain

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

palynology of late middle pennsylvanian coal beds in the appalachian basin abstract fossil spores and pollen have long been recognized as valuable tools for identifying and correlating coal beds this paper describes the palynology of late middle pennsylvanian coal beds in the appalachian basin with emphasis on forms that assist both intra and interbasinal coal bed correlation stratigraphically important palynomorphs that originate in late middle pennsylvanian strata include torispora securis murospora kosankei triquitrites minutus cadiospora magna mooreisporites inusitatus and schopfites dimorphus taxa that terminate in the late middle pennsylvanian include radiizonates difformis densosporites annulatus dictyotriletes bireticulatus vestispora magna and savitrisporites nux species of lycospora cirratriradites vestispora and thymospora as well as granasporites medius triquitrites sculptilis and t securis end their respective ranges slightly higher in earliest late pennsylvanian age strata late middle pennsylvanian and earliest late pennsylvanian strata in the appalachian basin correlate with the radiizonates difformis rd mooreisporites inusitatus mi schopfites colchesterensis s dimorphus cp and lycospora granulata granasporites medius gm spore assemblage zones of the eastern interior or illinois basin in the western interior basin these strata correlate with the middle upper portion of the torispora securis laevigatosporites globosus sg and lower half of the thymospora pseudothiessenii schopfites dimorphus pd assemblage zones in western europe late middle pennsylvanian and earliest late pennsylvanian strata correlate with the middle upper portion of the torispora securis t laevigata sl and the middle part of the thymospora obscura t thiessenii ot spore assemblage zones allegheny formation coal beds also correlate with the torispora securis x and thymospora obscura xi spore assemblages which were developed for coal beds in great britain

depositional environments and sequence stratigraphy of the late carboniferous early permian coal bearing successions shandong province china sequence development in an epicontinental basin abstract this study focuses on the late carboniferous early permian coal bearing successions in shandong province north china in order to understand the depositional processes and sequence stratigraphic framework in an epicontinental basin based on detailed analysis of eleven facies five facies assemblages fas were recognized in the studied succession fa1 3 are present mainly in the benxi and taiyuan formations and consist of mixed siliciclastic and carbonate lithofacies representing eluvial lagoon barrier lagoon and tidal flat environments fa4 occurs in the shanxi formation and consists mainly of interbedded medium to fine sandstone siltstone mudstone and coal lithofacies representing river dominated deltaic environments fa5 is characterized by interbeds of trough cross stratified coarse sandstone and silty mudstone mainly in the lower shihezi formation which was deposited in meandering river channel and floodplain three third order sequences were established based on the vertical arrangement of facies assemblages and identification of physical surfaces i e subaerial unconformity transgressive surface and regressive surface each sequence comprises a transgressive systems tract tst and a highstand systems tract hst tst of sequence 1 is composed of eluvial lagoonal deposits fa1 whereas hst formed in lagoon barrier and tidal flat settings fa2 and fa3 tst of sequence 2 formed in a barrier lagoon system fa2 whereas hst is characterized by repetitive accumulation of interbedded limestone sandstone mudstone and coal deposited under lagoonal and tidal flat settings fa2 and fa3 tst of sequence 3 comprises fa2 and hst mainly fa4 deposited in a river dominated shallow water delta system sequence 3 is overlain by a fluvial sequence fa5 the three third order sequences in the shandong region are generally correlated with those in the taebaeksan basin south korea the eastern part of the north china block the relative sea level curves established in the two regions show a generally similar long term rising trend

petrology and palynology of the no 5 block coal bed northeastern kentucky abstract the upper middle pennsylvanian middle westphalian d equivalent no 5 block coal bed eastern kentucky coal field of the central appalachian basin is a low sulfur compliance coal resource dominantly comprised of dull inertinite rich lithotypes ash yields tend to be highly variable in the no 5 block as does bed thickness and frequency of bed splitting this study describes the petrographic palynologic and geochemical characteristics of the no 5 block coal bed and reports on some temporal and spatial trends among these parameters in eastern northeastern kentucky petrographically the no 5 block coal is predominated by dull often high ash lithotypes with inertinite contents commonly exceeding 30 mmf the coal thins to the north northwest where it tends to be higher in vitrinite and sulfur content representatives of large and small lycopsids and ferns both tree like and small varieties dominate the no 5 block coal bed palynoflora calamite spores and cordaite pollen also occur but are less abundant small lycopsid densosporites spp and related crassicingulate genera and tree fern e g punctatisporites minutus laevigatosporites globosus spore taxa are most abundant in dull lithotypes bright lithotypes contain higher percentages of arboreous lycopsid spores lycospora spp regionally the no 5 block coal contains abundant torispora securis a tree fern spore specially adapted for desiccation prevention this along with overall high percentages of inertinite macerals suggest that peat accumulation may have taken place in a seasonally dry paleoclimate the no 5 block coal bed thickens rather dramatically in a nw se direction as does the frequency of coal bed splitting this phenomenon appears to be related to increased accomodation space in the southeastern portion of the study area perhaps via penecontemporaneous growth faulting maceral and palynomorph variations within the bed correspond with these changes thin coal along the northwestern margin tends to be vetrinite rich and contains abundant lycospora perhaps reflecting relatively stable peat forming conditions thicker coal to the southeast contains more inertinite high ash coal layers and inorganic partings spore floras contain more small lycopsid and tree fern components and are temporally variable perhaps indicating a more unstable peat forming environment

geometric models of porosity reduction by ductile grain compaction and cementation pore volume reduction of sediments by plastic deformation during compaction and by cementation of grains has been evaluated for different proportions of ductile and hard grains we represent the compaction behavior of grains with a purely geometric model which uses the cooperative rearrangement algorithm to produce dense random packings of partly interpenetrating spheres we varied the fraction of grains assumed to be ductile and the radius of the rigid core of the ductile grains the predicted relationship between the fraction of ductile grains in the sediment and the porosity after compaction agrees well with previously published experimental data in the literature the radius of the rigid core of the ductile grains is an effective way to represent different kinds of ductile material ranging from brittle rigid radius 0 9 to extremely ductile rigid radius 0 7 we simulated quartz cementation in our compacted rock by adding isopachous cement cement thickness was reduced on the smaller grains and increased on the larger grains to account for presumed export of pressure dissolved material from finer grained regions and the import of material into coarser grained regions these simulations yield descriptions of pore scale geometry resulting from processes common in sandstones modeled pore geometry provides insight into transport properties of such rocks for example the models predict to within a factor of five the permeability of samples of tight gas sandstones having little intragranular porosity

are coal balls rare a cyclostratigraphic analysis of coal ball occurrence in north america abstract from the perspective of phanerozoic time coal balls are rare apparently limited to a 24 m y interval 323 299 ma in the pennsylvanian and earliest permian yet within this interval coal balls occur in many coals approximately 82 transgressive regressive sedimentary cycles have been described for the midcontinent illinois and appalachian basins of north america during the mid to late pennsylvanian one third 27 82 have coal balls including 57 of major cycles 36 of intermediate cycles and 16 of minor cycles coal ball occurrence in the donets basin is similar over an interval of about 4 m y 315 311 ma latest bashkirian to mid moscovian 39 11 28 of transgressive regressive cycles have coal balls as north american paleoclimate became drier tree ferns replaced lycopsids as the dominant plant in peat swamps at the desmoinesian missourian boundary and coal ball occurrence declined overall 47 of cycles 19 40 with lycopsid or cordaitean dominance have coal balls whereas 19 8 42 of cycles with tree fern dominance have coal balls p this pattern may reflect the relative abundance of coal in the late pennsylvanian with drier paleotropical climates in the missourian virgilian leading to less paleotropical coal fewer mines and a lower probability of discovering missourian and virgilian coal balls however average cycle duration decreased from 150 kyr in the desmoinesian to 100 kyr in the missourian and virgilian and faster rates of relative sea level rise could have affected coal ball abundance particularly if coal balls formed in marine swamps with more rapid transgression leading to thinner coals or to freshwater coals directly overlain by marine sediments rygel et al 2008 suggested that missourian virgilian cycles recorded more erosional relief than desmoinesian cycles consistent with increased amplitude and rates of sea level rise during each glacial eustatic cycle changes in missourian virgilian cycles may have been augmented by stratigraphic attenuation as sediment filled the antecedent topography

preliminary investigation results on fabrics and related physical properties of an anisotropic gneiss abstract in order to evaluate the fabric dependent anisotropy of a particular gneiss type we assessed the quartz lattice and shape preferred orientations as well as the microcrack pattern statistics in the rock mechanics laboratory several strength and deformability tests on drilled rock samples were run and the seismic wave propagation properties along the rock s principal strain axes were determined in the mechanical tests it turned out that despite a distinct stretching lineation with initially extreme grain elongation the rock performs for the larger part as a transversely isotropic material with the schistosity as plane of isotropy the anisotropy in seismic wave propagation within the plane of schistosity is attributed primarily to a highly anisotropic microcrack pattern the distinct gneissose banding and to a lower degree to the lpo of quartz

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

palynological correlation of major pennsylvanian middle and upper carboniferous chronostratigraphic boundaries in the illinois and other coal basins

vegetational zonation in a swamp forest middle pennsylvanian illinois basin u s a indicates niche differentiation in a wetland plant community abstract a rich fossil flora occurs in the roof shale of the middle pennsylvanian moscovian age springfield coal flanking the galatia channel a river deposit approximately 1 km in width and 150 km long partially contemporaneous with the springfield peat swamp siltstone and sandstone 30 m thick were deposited in the channel during the final estuarine phase the river formed under seasonal subhumid climate during early deglaciation as marine waters retreated from the land surface it existed continuously through glacial maximum under increasingly humid climate as a low sediment or black water river with peat along its flanks during early deglaciation under subhumid climate and sea level rise the river became a sediment laden estuary drowning the peat swamp and burying vegetation in place under extensive mudflats this buried flora was studied in three underground mines in southern illinois permitting vegetation to be characterized spatially three transects comprising 100 sites a total linear distance of 12 km reveal distinct zonation perpendicular to the channel margin an innermost belt 0 5 to 2 5 km wide consists almost exclusively of the pteridosperm neuropteris flexuosa north of a river bend three belts succeed the n flexuosa zone mixed pteridosperms and marattialean tree ferns mixed arborescent lycopsids and marattialians lycopsids with rare marattialians south and inside the same bend n flexuosa is succeeded by mixed lycopsids particularly sigillaria and marattialean ferns within the transects marattialian ferns have wider distribution than other groups suggesting broader environmental tolerances neuropteris flexuosa channel margin mono dominance may reflect high sedimentation rates elevated nutrient conditions or floating seed dispersal lycopsid dominance in interior areas conforms with tolerance of deep standing water the spatial scale examined affects our perception of community assembly overall distinct vegetational zonation suggests niche assembly however within vegetational bands there is considerable small scale spatial variation suggesting stochastic properties

cyclic changes in pennsylvanian paleoclimate and effects on floristic dynamics in tropical pangaea abstract wetland floras narrowly define perceptions of pennsylvanian tropical ecosystems the so called coal age such wetlands reflect humid to perhumid climate leading to characterizations of pennsylvanian tropics as everwet swampy these views are biased by the high preservation potential of wetlands sedimentation patterns paleosols and fossil floras indicate the presence of vegetation tolerant of subhumid to dry subhumid perhaps semi arid climate in basins between peat formation times understanding the significance of this seasonally dry vegetation has suffered from conceptual and terminological confusion a clearer view has emerged as models for framing the data have improved basinal floras typical of seasonally dry conditions relatively low soil moisture regimes are well documented but mainly from isolated deposits some of the earliest dominated by primitive pteridosperms flozfern floras occur in clastic rocks between european early pennsylvanian coal beds later early pennsylvanian fern cordaitalean vegetation different from coal floras is preserved in marine goniatite bullions conifers are first suggested by late mississippian potoniesporites pollen about the same time in north america broadleaf foliage lesleya and megalopteris occur in basin margin settings on drought prone limestone substrates the best known xeromorphic floras found between coal beds appear in the middle through late pennsylvanian containing conifers cordaitaleans and pteridosperms the middle pennsylvanian appearances of this flora are mainly allochthonous though parautochthonous occurrences have been reported parautochthonous assemblages are mostly late pennsylvanian the conifer flora became dominant in western and central pangaean equatorial lowlands in earliest permian location of the humid perhumid wetland flora during periods of relative dryness though rarely discussed is as or more perplexing than the spatial location of seasonally dry floras through time wetland plants had few migratory options and possibly survived in small refugia within and outside of basins coupled oscillations in climate sea level and vegetation were driven most likely by glacial interglacial fluctuations perhaps controlled by orbital cyclicity

gravimetric terrain corrections by triangular element method terrain corrections for gravity data are a critical concern in rugged topography because the magnitude of the corrections may be large relative to the anomalies of interest the terrain correction process however is very tedious at present rectangular prism and fan shaped prism methods are commonly used for the corrections but these methods assume elements have horizontal tops an assumption which does not reflect true topography especially near the station a triangular element method which allows dipping surfaces has been developed using a gaussian formulation to improve the correction process this method involves a simple formula employing a surface rather than a volume integral for computing the terrain corrections with high accuracy

petrographic characteristics of intrusive rocks as an evaluation tool of their technical properties the main petrographic variables of intrusive rocks that influence the technical test methods common used within the aggregate industry were identified and evaluated the aim being to investigate wh

a conifer dominated palynological assemblage from pennsylvanian late moscovian alluvial drylands in atlantic canada implications for the vegetation of tropical lowlands during glacial phases abstract new research suggests that pennsylvanian coal forests were commonly replaced by conifer dominated vegetation during seasonally dry glacial phases here we describe palynological assemblages from stacked sequences of the middle pennsylvanian late moscovian sydney mines formation of nova scotia canada which lends some support to this hypothesis one critical sample from a widespread redbed succession below the harbour coal is dominated by conifer pollen 55 together with abundant representatives of cordaitaleans other coniferopsids and rare pteridosperms ferns and lepidodendrids it differs markedly from 13 other samples obtained from coals their roof shale limestone and associated channel bodies which are dominated by lepidodendrids marattialean tree ferns cordaitaleans and or calamiteans the latter beds represent coastal wetlands and are attributed to late transgressive and highstand systems tracts whereas the conifer bearing sample represents a dryland alluvial plain and may be attributed to lowstand or earliest transgressive systems tracts three additional samples from grey shale below a sequence boundary late highstand and between a redbed succession and major coal seam early to mid transgressive deposits contain transitional palynofloras with a high proportion of herbaceous gleicheniaceous and sphenopteroid ferns herbaceous lycopsids and sphenophylls interspersed with cordaitaleans and or lepidodendrids the dominance of conifer pollen within the dryland components of well defined sequences which have been linked to relative sea level change promoted by gondwanan glaciation supports the view that pennsylvanian tropical biomes responded to the beat of glacial interglacial cycles

a drowned lycopsid forest above the mahoning coal conemaugh group upper pennsylvanian in eastern ohio u s a over 800 mud filled casts of upright lycopsid tree stumps have been documented immediately above the mahoning coal in an active underground mine located in northwestern jefferson county ohio the coal body originated as a pod shaped peat body of 60 km2 trees are rooted at several levels within a thin 15 40 cm bone coal directly above the banded coal they extend upward up to 15 cm into overlying flat bedded carbonaceous mudstones that coarsen up from a maximum basal diameter of 1 2 m stumps taper upward to diameters no less than 0 3 m within single entry transects 6 m wide that total 2585 m in length stumps are randomly distributed the trees are identified as lepidodenrids on the basis of gross morphology external stem patterns and attached stigmarian root systems and provisionally as lepidophloios or lepidodendron by associated palynology of the enclosing matrix palynological analyses of incremental seam samples indicate an initial dominance of lycopsid spores with lepidodendracean affinities lycospora granulata from lepidophloios hallii replaced upwards by tree fern spores with a reoccurrence of lepidodendracean spores in the upper benches spores of sigillaria crassispora are abundant only at the base of the coal petrographic analyses indicate a prallel trend from vitrinite rich to inertinite and liptinite rich upward in the coal body all data indicate that the peat represented by the mahoning coal was drowned slowly during the earliest stages of inundation a lycopsid forest was re established only to be subsequently drowned

mechanical quality of bedrock with increasing ductile deformation abstract most of the rocks in precambrian shield areas have experienced a complex structural and metamorphic evolution processes which have a strong influence on bedrock quality the properties vary on both a local and a regional scale it is highly beneficial to know the variations in detail when exploiting the rocks for industrial purposes the main objective of the investigation was to study the variation of rock mechanical properties in an originally more or less isotropic rock at various stages of ductile deformation the rocks investigated were paleoproterozoic and with ages of ca 1 80 1 88 ga and the areas chosen for sampling were situated north east of lake vanern kristinehamn 10 samples south of the city of eskilstuna south central sweden 5 samples and south of odeshog near lake vattern in southern sweden 7 samples the 12 samples from the latter two areas are described in this investigation while the 10 samples from kristinehamn have been published earlier goransson et al 2004 a comprehensive study of various parameters of importance for bedrock quality has been performed on all samples e g studded tyre test stt and los angeles test la uniaxial compressive strength ucs ultrasonic velocity perimeter measurements of mineral phases and petrographic and chemical analyses the weakly deformed and massive more or less isotropic rocks show a tendency towards better properties of abrasion stt than the strongly deformed rocks and this can also be said for ucs reflecting the greater ability of rocks to split along foliation planes this is not entirely unambiguous as the more deformed rocks such as the mylonites may have varying properties this depends on the combined effects of e g grain size recrystallisation and foliation however the brittleness la shows somewhat better values with increased deformation this may depend on higher amounts of dark minerals as their existence does not affect this test as much as in the case of abrasion tests the perimeter values of the mineral phases display generally higher values i e grain boundaries for the more strongly deformed rocks are more complicated however the values for the investigated mylonites may vary between low and high the lower value may be due to dynamic recrystallisation and the creation of triple points static recrystallisation making the rock weaker besides the development of a strong foliation may decrease rock strength despite the usually finer grain size the results show that it is extremely important to consider all possible variations of bedrock before classification and exploitation as the bedrock material in fact is highly heterogeneous

assessment of rock geomechanical quality by quantitative rock fabric coefficients limitations and possible source of misinterpretations abstract rock microfabrics were quantified by image measurement system petrographic image analysis of thin sections along with common measured parameters grain area and size length of major and minor axes and their orientation some quantitative parameters aspect ratio grain boundary smoothness and fabric coefficients micropetrographic quality index k texture coefficient tc indexes of interlocking t and grain size homogeneity g were determined the reliability of these parameters for the evaluation of geomechanical properties was tested on the set of granitic rocks showing pronounced variability in rock mechanical properties none of the tested rock fabric coefficients or parameters proved a close correlation to rock mechanical properties except grain size based on experimental findings the grain size is along with porosity the controlling factor of rock mechanical properties of genetically and mineralogically similar rocks obliteration of the real effects of rock fabric parameters on the mechanical properties of rocks by application of complex fabric coefficients disables their practical use in petrography applied to geomechanics