control of relative sea level and climate on coal character in the westphalian c atokan four corners formation central appalachian basin u s a abstract peat successions preserved as coal seams preserve high resolution records of ancient terrestrial water table base level fluctuations that are driven by changes in relative sea level and or paleoclimatic change the aim of this study is to establish the roles of relative sea level and climate in controlling water table fluctuations within coal seams from the fluviodeltaic westphalian c bolsovian atokan four corners formation of the central appalachian basin usa comparison of the characteristics of 10 coals in the four corners formation with accommodation trends identified from analysis of intra coal clastic strata indicates that their thickness and vitrinite inertinite ratio correlate readily with the accommodation setting of the depositional sequence in which they occur coals that accumulated in relatively high accommodation fourth order sequences are high in vitrinite thin and overlain by or intercalated with marine and lacustrine sediments the coals have simple internal organization suggesting that they span parts of single high resolution accommodation cycles coals that accumulated in lower accommodation fourth order sequences are high in inertinite thick and overlain by or intercalated with terrestrial sediments the coals have composite internal organizations typified by multiple high resolution accommodation cycles and characteristic abrupt discontinuities of coal facies representing periods of depositional hiatus the correlations between the composition and thickness of the coals and the magnitude of associated marine transgression imply that relative sea level change was the principal control governing bulk accommodation in these mires landward of the paleoshoreline high frequency accommodation cycles within the coals reflect water table fluctuations in the original mires and were driven by high frequency sea level and or climate change the results of this study provide considerable insight into the manner in which coal composition and stratigraphy at a single locality vary over time in response to changing accommodation and provide a means to predict coal seam quality in an established sequence stratigraphic framework

incised channel fills containing conifers indicate that seasonally dry vegetation dominated pennsylvanian tropical lowlands the idea that the pennsylvanian tropical lowlands were temporally dominated by rainforest i e the coal forest is deeply ingrained in the literature here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact and that seasonally dry vegetation dominated instead this controversial finding arises from the discovery of a new middle pennsylvanian moscovian fossil plant assemblage in southeast illinois united states the assemblage which contains xerophytic walchian conifers occurs in channels incised into a calcic vertisol below the baker coal these plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase this xerophytic flora differs markedly from that of the typical clubmoss dominated coal forest developed during deglaciation events although preserved only very rarely we argue that such xerophytic floras were temporally as dominant and perhaps more dominant than the iconic coal forests which are overrepresented in the fossil record due to taphonomic megabias these findings require the iconography of pennsylvanian tropical lowlands to be redrawn

ecological gradients within a pennsylvanian mire forest pennsylvanian coals represent remains of the earliest peat forming rain forests but there is no current consensus on forest ecology localized studies of fossil forests suggest intermixture of taxa heterogeneity while in contrast coal ball and palynological analyses imply the existence of pronounced ecological gradients here we report the discovery of a spectacular fossil forest preserved over 1000 ha on top of the pennsylvanian desmoinesian herrin no 6 coal of illinois united states the forest was abruptly drowned when fault movement dropped a segment of coastal mire below sea level in the largest study of its kind to date forest composition is statistically analyzed within a well constrained paleogeographic context findings resolve apparent conflicts in models of pennsylvanian mire ecology by confirming the existence of forest heterogeneity at the local scale while additionally demonstrating the emergence of ecological gradients at landscape scale

on the nature of transverse variability in a coastal plain estuary even though estuarine processes are inherently three dimensional most of the previous studies have focused primarily on the axial longitudinal and vertical variabilities recent surveys in the lower delaware bay indicate the presence of significant transverse variability in the salinity distribution and residual circulation pattern conceptual models are developed to examine the mechanisms which might explain the observed transverse structure results indicate that both the gravitational effect and wind forcing are capable of generating substantial transverse structure in drowned river valley estuaries with triangular cross sections

the permian moradi formation of northern niger paleosol morphology petrography and mineralogy abstract three basic paleosol morphologies named type a type b and type c are described from the middle upper permian strata of the moradi formation tim mersoi basin northern niger the moradi formation is a typical alluvial redbed succession dominated by red mudrocks with fine to coarse grained pebbly channel sandstones and matrix breccias type a paleosols are hosted by well sorted fine to medium grained trough cross bedded and massive sandstones and preserve abundant vertical to horizontal micritic and microspar calcite tubules interpreted as rhizoliths lateral variability of rhizoliths in type a paleosols and their close association with fluvial channel fill sediments suggests they are the roots of grove stands of phreatophytic vegetation that grew within unstable anabranching stream systems type b paleosols are hosted by mudrocks and preserve well developed ped structure abundant micritic calcite nodules and vertically stacked micritic calcite nodular bodies as well as rare calcite with satin spar texture interpreted as a pseudomorphic replacement of pedogenic gypsum the morphology of type b paleosols suggests they were formed in well drained floodplain deposits on stable landforms type c paleosols are similar to type b but preserve pedogenic structures indicative of soil volume expansion and contraction as well as more abundant stage ii pedogenic carbonate nodules the morphology of type c paleosols suggests that they developed periodically rather than seasonally in poorly drained deposits that nevertheless occupied a relatively stable part of the landscape such as the plains flanking ephemeral lakes or sabkhas x ray diffraction analysis of the the range of morphologies petrographic textures and mineralogy of the paleosol profiles indicates semi arid to hyper arid climatic setting this paleoclimatic reconstruction is in agreement with middle and late permian conceptual paleoclimate models and quantitative general circulation models nevertheless and in spite of an arid climate moradi paleosols and their host strata also indicate a relatively shallow groundwater table importantly this shallow groundwater resource undoubtedly helped to support the moderately diverse fossil vertebrate assemblage and large stature macrophytes preserved in the moradi formation

palynological evidence for pennsylvanian extra basinal vegetation in atlantic canada abstract pollen preserved in latest westphalian and early stephanian clastic deposits of the sydney coalfield cape breton island suggest that there were zones of different vegetational habitats surrounding the wetlands where the coal forming peat was formed on the margins of the wetlands was a narrow band with large cordaitanthacean trees this was surrounded by occasionally dry9 habitats supporting schuetzia plants ruflorioid plants and aethophyllum like herbaceous conifers around this were mesic or seasonally dry habitats dominated by walchian conifers and disaccate producing peltasperms these in turn were surrounded by xeric or seasonally wet habitats dominated by ullmanniacean like conifers cycads and monosaccate producing peltasperms during latest westphalian and early stephanian times the mesic and xeric habitats encroached nearer the wetlands although the vegetation of the wetlands themselves remained essentially unaffected this vegetation change was not a response to climate change but probably to changing drainage patterns and topography in the surrounding hinterland the florinites producing cordaitanthaceans appear not to have been upland trees as previously suggested but occupied mainly coastal habitats or riparian habitats on the margins of the wetlands

late palaeozoic environmental changes an introduction the idea of this volume arose from our proposal to the palaeoclimatic session held at the european geosciences union general assembly 2011 conference in vienna austria although the original scope was broader the included contributions focus on palaeoenvironmental changes during the late palaeozoic late palaeozoic history is especially important in that it records an increase of tectonics diastrophism frequent sea level fluctuations and climatic changes all finally leading to the most geocratic time of earth s history with the formation of the supercontinent pangaea this volume includes a number of articles that discuss the fossil record around the late palaeozoic ice age and its decline during the carboniferous with its unusual plant proliferation soon after when the hottest and driest period in earth s history in the permian caused the development of huge sand seas on the land finally a biotic event the largest mass extinction in earth history at the permian triassic transition ends the palaeozoic world this volume addresses two key issues the palaeoclimate and depositional cycles both of which have a strong impact on the record of palaeoenvironmental changes and the understanding of environmental perturbations the vigorous current debate on the future climate of the globe inevitably increases our interest in past climates from a geological perspective climatic perturbations occurred many times before humans were on the planet climate varies on several timescales depends on many high order factors including tectonic uplift and the orbital wandering of the earth and as a result it changes through time consequently palaeoclimatic reconstructions are growing in their importance as they enable us to use the past as a key to the future the earth s system experiences various cycles of very different origin scale frequency amplitude phase and basic level from a geological perspective the cyclicity appears unidirectional like brownian motion however in the past the complex interaction of these cycles has led to catastrophic changes in earth s systems such as those during the late palaeozoic when palaeoclimatic and geotectonic cycles coincided these cycles are also influencing our lives and will do so in our future so their impact needs to be understood the geological archives record both the climatic and cyclic phenomena on local to regional scales including in the late palaeozoic as documented in this volume understanding these records will improve our predictions about climate phenomena in the future they also show that the present climatic perturbations are insignificant from a geological point of view changes in the late palaeozoic earth system are illustrated in this volume by case studies of fossil records from north and south america east and south asia south africa and australia and as regional reviews section one the methods include palaeoenvironmental analysis including palaeobiological sedimentological stratigraphic sequence stratigraphy palaeomagnetic and geochemical methods they describe various environmental settings from palaeodeserts through marine associated giant salt pans to shallow to deep marine records the articles report new data from less known study areas provide up to date data ordering and expand our knowledge of the evolution of marine and terrestrial environments climatic changes and biotic events in late palaeozoic time this special publication is divided into five chapters the first comprising articles focused on the broad descriptive character of late carboniferous to early triassic palaeoclimatic changes and stratigraphy with the latest part of this period in europe i e zechstein subsequent articles include more detailed studies of the geological periods grouped into the latest devonian to early carboniferous section two late carboniferous to early permian section three middle to late permian section four and finally the permian triassic transition section five a brief synopsis of individual papers is given below wopfner 2012 reviews westphalian early triassic palaeoclimatic conditions between samfrau comprising the southern margins of south america and south africa extending via antarctica

controls on permo carboniferous precipitation over tropical pangaea a gcm sensitivity study abstract a series of late paleozoic climate model simulations was developed using the genesis atmospheric general circulation model to investigate the independent roles of gondwanan deglaciation atmospheric co 2 rise and regional tectonism on the long term 10 6 yr evolution of continental precipitation over tropical pangaea the model results indicate that either deglaciation or a co 2 increase from 1 to 8 present atmospheric levels could have caused substantial drying and warming at low latitudes a result that is consistent with late paleozoic proxy records yet the atmospheric processes that led to drying differ between these cases the deglaciation of gondwana reduces low latitude temperature gradients in the southern hemisphere decreasing by as much as 60 the meridional overturning in the southern hemisphere winter cell of the hadley circulation the decline in overturning reduces convective precipitation over equatorial pangaea in contrast high levels of co 2 have little effect on the large scale meridional overturning circulation but increase continental temperatures leading to high evaporation rates and reduced available soil moisture the source of convective precipitation on land in comparison to deglaciation and p co 2 regional uplift erosion of the central pangaean mountains cpms has a secondary effect on tropical precipitation in genesis and cannot explain the long term aridification and warming of western pangaea we suggest that the deglaciation of gondwana and a concomitant rise in atmospheric p co 2 could explain much of the late paleozoic climate change over low latitude pangaea

secondary circulation in a highly stratified estuary observations from the hudson river estuary are presented to discuss the interaction between secondary flows and stratification in the vicinity of a headland during highly stratified conditions analysis of the cross stream momentum balance suggests that centrifugal accelerations are in near balance with the cross stream baroclincity results emphasize that the interaction between stratification and secondary flows can set up a cross stream internal seiche this results in a reduction and subsequent reversal of the secondary flows downstream of a headland simple scaling arguments suggest that the spin down time for tidally driven eddies is related to stratification

morphology and distribution of fossil soils in the permo pennsylvanian wichita and bowie groups north central texas usa implications for western equatorial pangean palaeoclimate during icehouse greenhouse transition analysis of stacked permo pennsylvanian palaeosols from north central texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings palaeosols of the eastern shelf of the midland basin exhibit stratigraphic trends in the distribution of soil horizons structure rooting density clay mineralogy and colour that record long term changes in soil forming conditions driven by both local processes and regional climate palaeosols similar to modern histosols ultisols vertisols inceptisols and entisols all bearing morphological mineralogical and chemical characteristics consistent with a tropical humid climate represent the late pennsylvanian suite of palaeosol orders palaeosols similar to modern alfisols vertisols inceptisols aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the lower permian strata the changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical moist conditions characterized by high rainfall in the late pennsylvanian to progressively drier semi arid to arid tropical climate characterized by seasonal rainfall in early permian time based on known late palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial pangea the pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regionalscale atmospheric circulation the trend towards a drier climate interpreted from the permian palaeosols may be recording the breakdown of this preexisting orographic effect and the onset of a monsoonal atmospheric circulation system over this region

sea level curve for pennsylvanian eustatic marine transgressive regressive depositional cycles along midcontinent outcrop belt north america at least 55 cycles of marine inundation and withdrawal are recognized in the mid desmoinesian to mid virgilian midcontinent outcrop sequence in north america they range from widespread major cycles classic cyclothems with deep water facies extending across the northern shelf through intermediate cycles persisting as marine horizons across the shelf to minor cycles developed on the lower shelf or as parts of major cycles biostratigraphic differentiation of the cycles should establish interbasinal correlation on a scale fine enough to allow evaluation of differential tectonics and sedimentation sequential groupings of cycles are more irregular than proposed megacyclothems or mesothems but they may be obscured by the distinctness of the major cyclothems estimates of cycle periods range from about 40 to 120 x 10 sup 3 yr for the minor cycles up to about 235 to 400 x 10 sup 3 yr for the major cyclothems the range for all cycles corresponds well to the range of periods of earth s orbital parameters that constitute the milankovitch insolation theory for the pleistocene ice ages and it further supports gondwanan glacial control for the pennsylvanian cycles even though the dominant period of the major pennsylvanian cyclothems is up to four times longer than the dominant 100 000 yr period inmore the pleistocene the shapes of both curves display rapid marine transgression rapid melting of ice caps and slow interrupted regression slow buildup of ice caps which suggest similar linkages between the climatic effects of the orbital parameters and ice cap formation and melting at the two different scales widely separated in time 28 references 3 figures less

community heterogeneity of early pennsylvanian peat mires reconstructions of pennsylvanian coal swamps are some of the most common images of late paleozoic terrestrial ecosystems all reconstructions to date are based on data from either time averaged permineralized peats or single site collections an erect in situ early pennsylvanian forest preserved above the blue creek coal black warrior basin alabama was sampled in 17 localities over an area of 0 5 km 2 resulting in the first temporally and spatially constrained pennsylvanian mire data set this three tiered forest was heterogeneous lycopsid and calamitean trees composed the canopy and lepidodendrids lepidophloios and sigillarians grew together at most sites more juvenile than mature lycopsid biomass occurs in the forest floor litter indicating a mixed age multicohort canopy pteridophytes tree fern and pteridosperms seed fern dominated as understory shrubs whereas sphenophyllaleans pteridophytes and pteridosperms composed the ground cover and liana tier the proportion of canopy understory and ground cover biomass varied across the forest low proportions of ground cover and liana taxa existed where canopy fossils accounted for 60 of the litter there is a distinct spatial clustering of sites with more or less understory or ground cover where canopy contribution was 60 where canopy biomass was low 50 understory shrubs contributed more biomass indicative of light interception and or competition strategies sphenopteris pottsvillea a ubiquitous ground cover plant is abundant in all sites except one where pteridosperm creepers and lianas dominate the litter interpreted to indicate total suppression of other ground cover growth ecological wet dry gradients identified in other pennsylvanian swamps do not exist in the blue creek mire with the interpreted wettest lepidophloios driest sigillaria and intermediate lepidodendron sensu latu taxa coexisting in most assemblages

from cyclothems to sequences the record of eustasy and climate on an icehouse epeiric platform pennsylvanian permian north american midcontinent the stratigraphic succession of the north american midcontinent contains a high resolution 100 000 year record of sea level and climate change spanning the pennsylvanian permian boundary outcrop based sequence stratigraphic analysis on the upper wabaunsee admire and lower council grove groups in kansas and nebraska reveals a hierarchy of fifty one fifth order meter scale cycles grouped into five fourth order composite sequences fifth order cycles are bounded by subaerial unconformities in nearshore settings and correlative conformities in offshore settings and are therefore very thin depositional sequences lowstand systems tracts observed only in nearshore deposits are expressed as sandy incised valley fills in these meter scale cycles transgressive systems tracts which are dominated by carbonate deposition include coastal evaporites indicating arid climatic conditions highstand systems tracts which are dominated by siliciclastic deposition include thin but persistent coals in muddy coastal successions indicating humid climatic conditions paleosols at sequence boundaries evolve from vertic to calcic indicating climate change from relatively humid to relatively arid conditions during subaerial exposure this indicates that relatively arid climate coincided with eustatic lows while relatively humid climate coincided with eustatic highs on this low latitude platform composite sequences are bounded by subaerial angular unconformities and display a transgressive regressive stacking pattern of meter scale cycles the high resolution stratigraphic record of the midcontinent helps constrain the rate and magnitude of environmental change in ancient icehouse conditions and can serve as a baseline of environmental change for comparison with other coeval successions

the so called paleophytic mesophytic transition in equatorial pangea multiple biomes and vegetational tracking of climate change through geological time abstract the paleophytic mesophytic and cenophytic were originally conceptualized as chronostratigraphic intervals not specific floras and were used principally in that way for about 100 years they supposedly reflected massive irreversible biotic changes on land that were thought to have happened about half a geological period prior to the changes in marine faunas that mark the more traditional geological era boundaries the terms were applied initially only to terrestrial rocks from the euramerican portions of equatorial pangea especially parts of central europe where the boundary between the paleophytic and mesophytic the eras of interest here was placed at the top of the german rotliegends more recently the terms have been coopted to describe vegetation types not chronostratigraphic units even to the point where specific linnean ordinal or class level clades evolutionary lineages of plants have been attributed solely to one vegetation type or the other at a global level furthermore the paleophytic mesophytic transition has been recognized in the largely taxonomically distinct vegetation types of temperate as well as the equatorial paleolatitudes the result of this conceptual coopting of terms that already were of questionable value is a blurring of the concepts almost to the point of meaninglessness a reading of the literature indicates confusion in terms of what represents the paleophytic flora vs the mesophytic flora the botanical basis for the floras and the taxonomic scale at which they can be recognized the geographic pattern and temporal correlation of the supposed transition and the evolutionary and ecological significance of the vegetational changes these terms supposedly capture we propose that these terms be completely and utterly abandoned as confusing and worse yet misleading evidence suggests that paleozoic vegetation tracked climate which should not come as a surprise in light of what is known of plant dynamics in the holocene and recent furthermore the evidence for a global paleophytic vs mesophytic vegetation is simply unsubstantiated by the fossil record rather there appears to have been a complex of global species pools reflecting climate at many spatio temporal scales the vegetational changes occurring in the late paleozoic thus can be understood best when examined as spatial temporal changes in biome scale species pools responding to major global climate changes locally and regionally manifested

secondary currents in a curved stratified estuarine channel this paper presents a study of secondary circulation in a curved stratified channel in northern san francisco bay over a 12 5 hour tidal cycle secondary currents were strong at times varying by up to 35 cm s from top to bottom but relatively transient as the balance between centrifugal and lateral baroclinic forcing changed over time the short travel time around the bend did not allow a steady state balance to develop between centrifugal and lateral baroclinic forcing during the flood tide the confluence of two streams with different velocities produced a strong lateral gradient in streamwise velocity as a result lateral advection was a significant term in the streamwise momentum balance having the same order of magnitude as the barotropic and baroclinic pressure gradients and the frictional terms during the first part of the ebb secondary currents were induced by lateral baroclinic forcing the direction of the secondary circulation reversed later in the ebb as the baroclinic forcing became weaker than the centrifugal acceleration the gradient richardson number showed that stratification was stable over most of the tidal cycle decreasing the importance of friction and allowing secondary currents to persist

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

pennsylvanian tropical rain forests responded to glacial interglacial rhythms pennsylvanian tropical rain forests flourished during an icehouse climate mode although it is well established that milankovitch band glacial interglacial rhythms caused marked synchronous changes in pennsylvanian tropical climate and sea level little is known of vegetation response to orbital forcing this knowledge gap has now been addressed through sequence stratigraphic analysis of megafloral and palynofloral assemblages within the westphalian d cantabrian sydney mines formation of eastern canada this succession was deposited in a low accommodation setting where sequences can be attributed confidently to glacio eustasy results show that long lived low diversity peat mires dominated by lycopsids were initiated during deglaciation events but were mostly drowned by rising sea level at maximum interglacial conditions only upland coniferopsid forests survived flooding without significant disturbance mid to late interglacial phases witnessed delta plain progradation and establishment of high diversity mineral substrate rain forests containing lycopsids sphenopsids pteridosperms cordaites and tree ferns renewed glaciation resulted in sea level fall paleovalley incision and the onset of climatic aridity glacial vegetation was dominated by cordaites pteridosperms and tree ferns hydrophilic lycopsids and sphenopsids survived in paleovalley refugia findings clearly demonstrate the dynamic nature of pennsylvanian tropical ecosystems and are timely given current debates about the impact of quaternary glacial interglacial rhythms on the biogeography of tropical rain forest

compositions of mercury s earliest crust from magma ocean models article i nfo article history the size of the mercurian core and the low ferrous iron bearing silicate content of its crust offer constraints on formation models for the planet here we consider a bulk composition that allows endogenous formation of the planet s large core and by processing the mantle through a magma ocean would produce a low iron oxide crust consistent with observations more earth like bulk compositions require silicate removal perhaps by a giant impact to create the planet s large core fraction we find that the endogenous model can produce a large core with either a plagioclase flotation crust or a low iron oxide magmatic crust because a magma ocean creates a gradient in iron oxide content in the resulting planetary mantle the parts of the mantle removed by a putative giant impact could result in either a high iron oxide mantle in contradiction to current crustal measurements or a low iron oxide mantle consistent with the current understanding of mercury if a giant impact cannot preferentially remove shallow mantle material then the proto mercury must have had a bulk low iron oxide composition thus a specific bulk composition is required to make mercury endogenously and either a specific process or a specific composition is required to make it exogenously through giant impact measurements taken by the messenger mission when compared to predictions given here may help resolve mercury s formation process

record of glacial eustatic sea level fluctuations in complex middle to late pennsylvanian facies in the northern appalachian basin and relation to similar events in the midcontinent basin abstract pennsylvanian cycles in the northern appalachian basin nab were historically considered to result from delta lobe switching and more recently from sea level fluctuation with sandy deltas prograding during highstand these interpretations are revised using new data from cores and outcrop exposures thick 5 m channel deposits with a marked erosion surface at their base cutting down across previous cycles are re interpreted as incised valley fill ivf deposits in paleovalleys because the basal erosion surfaces are widespread and thus reflect a record of lowstand most common are simple paleovalleys that contain mainly sandy fluvial deposits compound paleovalleys with sequence boundaries above the basal erosion surface contain terrestrial estuarine and marine deposits early to late highstand deposits in interfluvial parts of the cycles are dominated by shale and mudstone with paleosols coals and local non marine limestone which reflect floodbasin to lacustrine conditions these reinterpretations are applied to previously and newly recognized cycles in ascending order upper kittanning lower freeport upper freeport leader new upper freeport piedmont new mahoning mason interval locally includes upper new galilee in the north and brush creek across a 300 km arc in the northern appalachian basin these deposits accumulated in a high shelf setting that experienced fewer marine transgressions and were interrupted by more frequent exposure and downcutting in contrast to the thicker and more complete succession with more numerous marine units in the midcontinent magnitudes of highstand transgressions into this basin deduced from the up dip extent of marine and brackish fossil assemblages were greatest for the brush creek less so for the upper kittanning and mahoning and least for the lower freeport upper freeport leader piedmont and mason the anomalous basin wide fresh water roofshales and equivalents of the upper freeport coal may reflect ponding of fresh water to the north by an elevated area that prevented marine encroachment at the southern opening of the basin along the kentucky ohio border maximum thicknesses of ivf deposits in each cycle are used as a proxy for estimating the minimum depth of lowstand incision preceding transgression while the thickness of ivf deposits in most cycles ranges from 6 to 20 m the two thickest are 30 m thick one associated with the pre mahoning paleovalley and the other with the immediately post mahoning paleovalley the extent of transgression of each cycle in the nab is roughly equivalent to those of their age correlative major marine cyclothems pawnee through swope in the midcontinent moreover the amount of incision between them is also roughly equivalent to the amount of regression between each of the roughly coeval cyclothems in the midcontinent with the deepest incisions in the nab pre mahoning and post mahoning corresponding to the greatest southward withdrawals of the sea in the midcontinent memorial and seminole hepler during this same interval

co2 forced climate and vegetation instability during late paleozoic deglaciation the late paleozoic deglaciation is the vegetated earth9s only recorded icehouse to greenhouse transition yet the climate dynamics remain enigmatic by using the stable isotopic compositions of soil formed minerals fossil plant matter and shallow water brachiopods we estimated atmospheric partial pressure of carbon dioxide pco2 and tropical marine surface temperatures during this climate transition comparison to southern gondwanan glacial records documents covariance between inferred shifts in pco2 temperature and ice volume consistent with greenhouse gas forcing of climate major restructuring of paleotropical flora in western euramerica occurred in step with climate and pco2 shifts illustrating the biotic impact associated with past co2 forced turnover to a permanent ice free world

high precision u pb zircon age calibration of the global carboniferous time scale and milankovitch band cyclicity in the donets basin eastern ukraine 1 high precision id tims u pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic cyclostratigraphic and biostratigraphic framework of the carboniferous donets basin of eastern europe chemical abrasion of zircons use of the internationally calibrated earthtime mixed u pb isotope dilution tracer and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of 0 05 or 100 ka for these carboniferous volcanics this precision allows the resolution of time in the milankovitch band and confirms the long standing hypothesis that individual high frequency pennsylvanian cyclothems and bundles of cyclothems into fourth order sequences are the eustatic response to orbital eccentricity 100 and 400 ka forcing tuning of the fourth order sequences in the donets basin to the long period eccentricity cycle results in a continuous age model for the middle to late pennsylvanian moscovian kasimovian ghzelian strata of the basin and their record of biological and climatic changes through the latter portion of the late paleozoic ice age detailed fusulinid and conodont zonations allow the export of this age model to sections throughout euramerica additional ages for mississippian strata provide among the first robust radiometric calibration points within this subperiod and result in variable lowering of the base ages of its constituent stages compared to recent global time scale compilations

relationship between petrographic and chemical properties and coal seam geometry hance seam breathitt formation southeastern kentucky the upper hance coal seam in southeastern kentucy was used as a template to examine the spatial distribution of ash yield sulfur content and petrographic constituents relative to the geometry of the deposit geometric characteristics include thinning and splitting of the two main benches leaders and riders analytical data showed the thick non split portions of the coal body to be low in ash and sulfur as well as vitrinite content whereas the thinned and split margins were higher in ash sulfur and vitrinite content these relationships suggest that thick non split portions of the upper hance peat accumulated in areas isolated from detrital influx while thinner marginal peat was subject to intermittent flooding from adjacent channels marginal peat was derived from larger trees which flourished at the mire s edge in the presence of adequate nutrients whereas only stunted vegetation subsisting in the nutrient depleted center contributed to interior peat accumulation ponds formed on the sparsely vegetated mature surface of the bog s interior the petrographic and chemical character of the hance coal body is analogous to ombrogenous domed peats which characteristically contain higher concentrations of inorganics at the periphery of the deposit

impact of longer term modest climate shifts on architecture of high frequency sequences cyclothems pennsylvanian of midcontinent u s a abstract pennsylvanian glacioeustatic cyclothems exposed in kansas and adjacent areas provide a unique opportunity to test models of the impact of relative sea level and climate on stratal architecture a succession of eight of these high frequency sequences traced along dip for 500 km reveal that modest climate shifts from relatively dry seasonal to relatively wet seasonal with a duration of several sequences 600 000 to 1 million years had a dominant impact on facies sediment dispersal patterns and sequence architecture the climate shifts documented herein are intermediate both in magnitude and duration between previously documented longer term climate shifts throughout much of the pennsylvanian and shorter term shifts described within individual sequences climate indicators are best preserved at sequence boundaries and in incised valley fills of the lowstand systems tracts lst relatively drier climate indicators include high chroma paleosols typically with pedogenic carbonates and plant assemblages that are dominated by gymnosperms mostly xerophytic walchian conifers the associated valleys are small 4 km wide and 20 m deep and dominated by quartz sandstones derived from distant source areas reflecting large drainage networks transgressive systems tracts tst in all eight sequences generally are characterized by thin extensive limestones and thin marine shales suggesting that the dominant control on tst facies distribution was the sequestration of siliciclastic sediment in updip positions highstand systems tracts hst were significantly impacted by the intermediate scale climate cycle in that hsts from relatively drier climates consist of thin marine shales overlain by extensive thick regressive limestones whereas hsts from relatively wetter climates are dominated by thick marine shales previously documented relative sea level changes do not track the climate cycles indicating that climate played a role distinct from that of relative sea level change these intermediate scale modest climate shifts had a dominant impact on sequence architecture this independent measure of climate and relative sea level may allow the testing of models of climate and sediment supply based on modern systems

three dimensional tidal flow around headlands field measurements of tidal flow around a headland indicate secondary circulation induced by flow curvature the secondary flow defined to be the flow in the plane normal to the direction of the vertically averaged current is directed toward the headland near the bottom and seaward near the surface consistent with theoretical predictions the strength of the secondary flow varies from 5 to 15 of the streamwise flow it is strongest when the water column is stratified because of both the enhanced shear of the streamwise flow and the reduced frictional damping of the secondary flow the transverse exchange accomplished by the secondary flow significantly influences the structure of the streamwise flow causing a broadening of the transverse shear and changing the horizontal and vertical distributions of momentum it may also have a significant influence on horizontal dispersion in the vicinity of headlands

the importance of aspiration and channel curvature in producing strong vertical mixing over a sill on the basis of observations of the time dependent tidally forced flow over a long sill we find that aspiration and channel curvature set the flow structure and condition the flow to allow intense vertical mixing aspiration reduces the potential energy of the water column by thinning it while maintaining its density contrast channel curvature induces a cross channel circulation that can rapidly overturn a stratified flow eighteen along channel sections of density velocity and dissipation rate of turbulent kinetic energy were collected in and around the tacoma narrows of puget sound a site suspected of driving a strong vertical circulation in adjoining main basin rapid inflow to the narrows on flood from one channel of a triple junction reduces dynamic pressure allowing dense water from below sill depth to be uplifted or aspirated into the narrows we estimate water from below 150 m 3 times the sill depth is drawn into the narrows on a 3 m flood tide once in the narrows the flow remains stratified until it passes a 50 bend where a strong secondary circulation overturns the 50 m deep water column and generates intense turbulent mixing cross channel velocities of up to 0 4 m s 1 are observed and maximum values of exceed 10 3 w kg 1 upon leaving the sill stratification is reestablished and turbulence decays a similar set of sequences occurs on ebb except that the outflow bypasses the flood inflow channel and instead discharges into colvos passage the third branch of the triple junction colvos passage ultimately discharges the ebb effluent back into main basin enhancing the impact of mixing at the narrows by discharging the mixed product far from the source scaling of the cross channel momentum equation suggests that below a threshold value of along channel velocity stratification should suppress secondary circulation for a given vertical shear radius of curvature and channel width above the threshold velocity the magnitude of the cross channel velocity is roughly consistent with predictions for unstratified flow we estimate the maximum effective eddy diffusivity that aspiration and mixing in the narrows can produce in main basin to be 10 3 m2 s 1

peat or no peat why do the rajang and mahakam deltas differ abstract coastal and deltaic holocene peat accumulations around the equatorial island of borneo southeast asia have served as models for economic coal bearing sequences in the stratigraphic record although climatic conditions vegetational communities and sedimentary regimes are comparable peat accumulations are not found on both the western and eastern sides of the island the rajang river delta and coastal plain sarawak east malaysia are covered in areally extensive thick peat deposits that have attained at least a thickness of 13 m in ombrogenous peat domes marudi baram river peat swamp biomass began to accumulate over pleistocene podzols when sea level stabilized 7 5 ka and delta progradation was initiated the mahakam river delta and coastal plain east kalimantan indonesia also began progradation at this time but there is no evidence in any part of the coastal region for peat accumulation rather poorly developed organic rich gleysols occur throughout the delta plain both the rajang river and mahakam river deltas are tidally influenced fine grained systems with a sediment provenance in the central massif sediment transported through the rajang river delta differs in that as much as 60 of the clay minerals deposited in the system are mixed layer i s and expandable k e clays that act to restrict pore water flow in the tidal and overbank deposits that comprise the delta plain these result in the development of an aquiclude above which paludal conditions develop promoting accumulation of organic matter in contrast there is a low proportion of mixed layer and expandable clays transported in the mahakam river system this precludes the development of a stilted water table within the delta allowing for organic matter recycling without peat accumulation the presence of a high proportion of expandable clay minerals on the western side of borneo is a reflection of the weathering and eroding source rocks on this side of the central borneo massif

coal compositional changes along a mire interior to mire margin transect in the mary lee coal bed warrior basin alabama usa abstract vertical increment samples of the mary lee coal bed collected along an inferred mire interior to mire margin transect were studied palynologically petrographically and geochemically to determine if any vertical or lateral changes in coal composition could be detected results show the mary lee palynoflora to be dominated by lycospora spp arboreous lycophytes with other lycophyte genera crassispora sigillaria and densosporites small lycophytes occurring less frequently commonly encountered fern pteridosperm miospore genera include leiotriletes granulatisporites lophotriletes and schulzospora calamospora representing calamites and florinites representing cordaites are minor constituents of the overall palynoflora petrographically the mary lee coal bed contains high percentages 75 mineral matter free mmf of vitrinite macerals with cryptotelinite being by far the most common type cryptogelocollinite is the second most abundant vitrinite maceral inertinite maceral percentages are variable ranging from 8 to 30 mmf and liptinite macerals are a relatively minor constituent of the mary lee coal bed 3 8 mmf both vertical and lateral changes in coal composition occur along the transect studied lateral changes include an increase in ash yield and sulfur content from the interior to margin for example the average ash yield and sulfur content at location 073 most interior are 13 7 and 0 55 respectively whereas at location 083 most marginal the average ash and sulfur values calculated from coal increments only are 32 3 and 3 62 respectively palynofloral changes from the interior to margin include a general increase in lycospora pusilla lepidodendron over lycospora pellucida lepidophloios and an increase in fern and calamite spores and cordaite pollen an increase in poorly preserved miospore assemblages was also observed in this direction at locations 016 and 026 coal increments between the lower and middle partings were barren of palynomorphs except for one increment in column 016 petrographically these increments were completely 95 mmf dominated by cryptotelinite both liptinite and inertinite macerals were conspicuously absent in contrast increments above the middle partings at these locations contained elevated percentages of inertinite macerals relative to more interior locations vertical changes were also noted at mire interior locations basal coal layers contain either an arboreous lycophyte dominant assemblage with abundant lycospora pusilla or a lycophyte fern pteridosperm co dominant assemblage this palynoflora grades upward into a lycospora pellucida l granula dominant palynoflora in the middle layers and ultimately into a palynoflora containing an abundant fern pteridosperm element petrographically the coal at these locations is dominated overall by cryptotelinite with an increase in inertinite occurring in the uppermost increments the overall dominance of arboreous lycophytes and cryptotelinite in the mary lee coal bed suggests that the mary lee paleomire developed under predominantly wet conditions the moderate at interior locations to high at marginal locations ash yield of the coal further suggests that the mire developed under planar to near planar conditions

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

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

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

gypsum to anhydrite transition in the miocene of southern poland abstract gypsum deposits in the carpathian foredeep of southern poland were altered daring burial to anhydrite this alteration did not completely destroy primary lithologic features different gypsum lithotypes have equivalents in the altered sulfate sections relics of and pseudomorphs after crystalline and sedimentary structures indicate that extensive replacement and cementation occurred early during burial diagenesis the replacement of gypsum by anhydrite was probably initiated in the shallow subsurface by high temperature and or reaction with brines of high salinity accordingly the importance of a deep burial for gypsum diagenesis in the studied area may have been overestimated

application of sequence and genetic stratigraphic concepts to carboniferous coal bearing strata an example from the black warrior basin usa carboniferous strata provide an excellent example on which to test the application of genetic stratigraphic and sequence stratigraphic concepts both approaches are employed in the evaluation of the coal bearing strata of the black warrior basin south eastern usa bounding hiatal surfaces have been recognized in the succession of rock that includes the mary lee coal zone within the framework of genetic stratigraphy one genetic sequence has been identified comprised of offlap progradational and aggradational facies and onlap aggradational and transgressive facies components seven parasequence sets have been delimited according to the concepts of sequence stratigraphy these have been ascribed to transgressive highstand and shelf margin systems tracts the identification of components of these contrasting frameworks provide the basis for evaluating other carboniferous strata

late pennsylvanian aridification on the southwestern margin of gondwana paganzo basin nw argentina a regional expression of a global climate perturbation abstract paleosols of the paganzo group preserve a shift from the cool climate of the glaciated high latitudes of gondwana to a long term aridification punctuated by shorter term fluctuations in moisture regime in the late carboniferous a quantitative reconstruction of paleoclimate inferred from the major element chemistry of paleosol horizons and the stable isotope geochemistry of soil formed minerals and organic matter indicates that the climate varied substantially during deglaciation along the southwestern margin of gondwana in the middle pennsylvanian including two geologically abrupt shifts to notably drier conditions this dynamic climate terminates in a dry subhumid moisture regime characterized by steppe dry scrub floral provinces quantitative estimates of net primary production during the post glacial interval inferred from paleosol major element geochemistry are consistent with a mesic soil temperature regime in agreement with paleotemperatures inferred from pedogenic goethite d and 18 o contemporaneous aridification is well expressed in paleotropical continental records with middle to late pennsylvanian aridification coincident with an abrupt evolutionary change in many marine and terrestrial species the synchrony of aridification between the high and low paleo latitudes and concomitant major restructuring of some ecosystems suggests that a paleoclimate change of global nature occurred during the moscovian and kasimovian

vertisol carbonate properties in relation to mean annual precipitation implications for paleoprecipitation estimates abstract previous publications combining the properties of multiple soil orders show that depth to carbonate dtc increases systematically between 350 and 1000 mm of mean annual precipitation map we hypothesize that carbonate in vertisols clay rich shrink swell soils respond differently to water flux than other soil orders because of lower permeability to test this hypothesis we compiled soil description and characterization data from multiple published sources across a late pleistocene climosequence of the coast prairie of texas to assess the relationship between map 700 1400 mm and dtc the dtc of carbonate nodules represents an index of accumulation and the dtc of calcium carbonate equivalent total carbonate 2 0 mm diam an index of leaching the dtc for 1 2 and 5 abundances were assessed using regression analysis the r2 values were highest for the dtc of 2 nodules and of 1 calcium carbonate equivalent in vertisol microlows surprisingly relatively high r2 values were calculated

vegetation heterogeneity on a late pennsylvanian braided river plain draining the variscan mountains la magdalena coalfield northwestern spain article the spatial heterogeneity and community ecology is reconstructed for late pennsylvanian stephanian b sensu lato vegetation preserved in la magdalena coalfield northwestern spain the 1500 m thick basin fill accumulated rapidly along the margin of the variscan mountains and the principal sedimentary facies comprise the deposits of large braided streams that dissected extensive wetlands containing large lakes quadrat analysis of 93 mostly par autochthonous megafloral assemblages indicates that pteridosperms and ferns dominated communities with three taxa pecopteris spp callipteridium pteridium and neuropteris ovata accounting for 58 of all plant remains sphenopsids and lycopsids were less common but widespread and cordaitaleans were rare at the local scale laterally exposed bedding planes reveal that communities comprised a complex and heterogeneous mosaic of species at the landscape scale ecological gradients are evident from multivariate analyses of quadrats in a facies context pteridosperms dominated marginal wetlands adjacent to steep basin margins a greater proportion of ferns occurred in or adjacent to

an abandoned channel fill with exquisitely preserved plants in redbeds of the clear fork formation texas usa an early permian water dependent habitat on the arid plains of pangea abstract a well preserved plant assemblage at the colwell creek pond locality of leonardian kungurian age provides an opportunity to evaluate taphonomic conditions in a dryland alluvial setting a narrow channel body incised to 5 m depth through red paleo vertisols contains 2 m of varicolored laminated mudstone with graded layers and plant material x ray diffraction analysis of individual laminae indicates the presence of chlorite illite kaolinite and mixed layer clay with hematite in red and gray layers and goethite in yellow brown laminae no carbonate was identified and the total organic carbon content is minimal the fine sediment accumulated in a shallow abandoned channel from suspension and gentle underflows probably linked to seasonal inflow and analysis of lamina thickness suggests that standing water may have persisted for up to a few millennia the preservation of lamination is attributed to a lack of bioturbation possibly linked to a paucity of subsurface oxygen low productivity elevated salinity rapid deposition or a combination of these factors minimal bioturbation may also reflect the limited use of freshwater ecospace during the early permian clay rich paleo vertisols complete the fill with drab root traces that indicate growth of vegetation in a strongly seasonal setting abundant plant material in the laminated beds includes branches of walchian conifers the possible cycadophyte taeniopteris spp and the comioid possible peltasperm auritifolia waggoneri they were derived from an adjacent riparian zone and preserved as 3d goethite petrifactions much of the foliage shows evidence of arthropod herbivory although a humid climatic episode cannot be ruled out the exceptional abundance and preservation of the plants probably reflects the persistence of an oxbow lake on a relatively arid alluvial plain where riparian plants experienced periodic moisture stress but had access to groundwater nearly year round rapid burial in standing water the lack of bioturbation in the laminated sediments and early biomineralization probably explain the exceptional preservation of the plant remains

late paleozoic tropical climate response to gondwanan deglaciation coupled climate biome model simulations of the late paleozoic were developed to determine the response of pangean tropical climate to gondwanan deglaciation the model simulations predict substantial changes over equatorial pangea including continental drying a reversal of equatorial winds warming heavier 18 o values of meteoric precipitation and the expansion of deserts and the contraction of forests the magnitude of these tropical responses is sensi tive to the extent of gondwana continental ice and the deglacial rise in atmospheric pco 2 boundary conditions that are not well known for the late paleozoic nonetheless the model predictions are consistent with climatic and environmental trends determined from terrestrial proxy data implying that the deglaciation of gondwana was a transformational climate event in tropical pangea

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

evolution of some depositional models in late carboniferous rocks of the appalachian coal fields abstract models for carboniferous coal bearing strata developed early in this century and consisted of vertical columns that described commonly occurring sequences of coal beds and associated rocks these were followed by other models that expressed patterns of both vertical and lateral variation but in those as well as earlier models depositional interpretation did not extend much beyond a basic marine nonmarine dichotomy subsequently depositional processes were linked to lithic components and showed that the areal distribution of these components formed a lateral geomorphically controlled continuum ranging from alluvial plains seaward to barrier islands evaluation of this model within a tectonic setting of rapid and differential subsidence produced by growth faulting in the southern part of the appalachian coal fields has shown that while depositional processes are substantially the same as those suggested by the model the form and spatial distribution of resulting lithic components are profoundly affected by movements on contemporaneously active subsurface structures this leads to the conclusion that previous models are a product of depositional processes strongly controlled by their tectonic setting and that further attempts at model generation will require careful assessment of the relationships of lithic distribution to subsurface structures and amounts of data necessary to recognize them

conservatism of late pennsylvanian vegetational patterns during short term cyclic and long term directional environmental change western equatorial pangea the fossil record offers a unique opportunity to track species pools through time and to examine their responses to long term directional changes in physical conditions the ability to estimate environmental variables such as temperature rainfall amount and its seasonal distribution and atmospheric co2 is improving continuously links between proxy measures of such physical factors and quantitative data on changes in ecosystem composition and dynamics formerly the purview of pleistocene palaeoecology are now available even in the deep past for both terrestrial e g wing et al 2005 falcon lang et al 2006 montanez et al 2007 secord et al 2008 currano et al 2008 tabor et al 2011 and marine palaeozoic examples olszewski erwin 2009 ivany et al 2009 fall olszewski 2010 bonelli patzkowsky 2011 holland zaffos 2011 systems plant fossils themselves can be especially useful as palaeoclimate proxies even in the distant world of the palaeozoic e g falcon lang et al 2009 because of the strong sensitivities of plants to habitat and regional climate as sessile organisms plants are directly and inextricably linked to climate at the level of individual population local community and biome quantitative floristic studies of vegetation from the late palaeozoic are numerous e g scott 1978 pfefferkorn thomson 1982 bartram 1987 eble et al 1994 2006 pryor gastaldo 2000 dimichele et al 2007 oplustil et al 2007 sim nek martinek 2009 libertin et al 2009 bashforth et al 2010 although few have had a framework with which to link plants and their associated environments to changing global climate e g phillips peppers 1984 falcon lang 2004 it is a particular challenge to find a long relatively uninterrupted stratigraphic section that contains both a common species pool or pools and a clear signal of an overall directional and interpretable environmental change the latest pennsylvanian earliest permian markley formation of north central texas provides such an opportunity the markley fm was positioned in the western pangean tropics during the pennsylvanian permian transition a time of global climate change that accompanied the onset of permian glaciation fielding et al 2008 within the markley fm its partial equivalent the harpersville fm and into the base of its successor the archer city fm there are distinct packets of lithofacies that repeat in the stratigraphic section each lithofacies contains a distinctive fossil plant assemblage characterized and described by romanchock et al in press which can be followed through the markley fm the goal of this paper is to go beyond such a qualitative flora to facies correlation and to examine quantitatively the floristic similarity within and among these facies in space and through time in order to investigate and in this instance document the coherence of species assemblages in the face of short term and long term environmental changes and to evaluate spatio temporal scales on which niche versus neutral biological community assembly patterns may operate e g alonso et al 2006 weiher et al 2011 in addition we wish to examine the conformance of the markley fm data with interpretive models that call for climate change as the controlling variable on repeating patterns of lithofacies and plant distribution through time in the short and long term allocyclicity v models that call for changes in sedimentary environments as the driver of temporally recurrent floristic change under a relatively constant background climate autocyclicity

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics

the pennsylvanian tropical biome reconstructed from the joggins formation of nova scotia canada the pennsylvanian langsettian joggins formation contains a diverse fossil assemblage first made famous by lyell and dawson in the mid 19th century collector curves based on c 150 years of observation suggest that the joggins fossil record is relatively complete a key feature of the site is that fossils occur in par autochthonous assemblages within a narrow time interval

the westphalian stephanian macrofloral record from the south wales coalfield uk the south wales coalfield has the most complete westphalian macrofloral record anywhere on the variscan foreland or adjacent basins with 135 biodiversity meaningful morphospecies having been recognized all of the standard macrofloral biozones of the westphalian stage have been recognized although a detailed comparison with the central pennines coalfields has indicated some discrepancies in the relative positions of the biozonal boundaries total species richness progressively increases through the langsettian substage and then remains relatively stable through most of the duckmantian and bolsovian substages there is a distinct reduction in total species richness towards the top of the bolsovian substage but this partially recovers in the middle asturian substage with the appearance of a range of marattialean ferns and medullosalean and callistophytaleans pteridosperms there is no evidence of any significant drop in total species richness towards the top of the succession indicating that conditions at this time were relatively stable the change from coastal floodplain to alluvial braidplain conditions in middle bolsovian times correlates with a marked increase in the proportion of medullosalean remains being preserved in the adpression record reflecting an expansion of the clastic substrate habitats