soils surficial geology and geomicrobiology of saline sodic wetlands north platte river valley nebraska usa abstract saline sodic wetlands along a 200 km stretch of the north platte river valley in western nebraska usa lie within an important agricultural region but their processes salt mineralogy and geomicrobiology have not previously been investigated putative anthropogenic salinization has long been a concern yet early historical accounts of widespread surface salts in the area have never been applied as comparative standards surface salts in the area originate from soil capillarity and surface evaporation thenardite na 2 so 4 and or mirabilite naso 4 10 h 2 o dominate depending on ambient conditions bloedite na 2 mg so 4 2 4 h 2 o halite nacl burkeite na 6 co 3 so 4 2 and calcite caco 3 are minor constituents historical accounts indicate that salts accumulated naturally long before euramerican settlement apparently as a result of rock water interaction in nearby volcaniclastic sediments of the brule formation ephemeral to permanent water holding basins in the wetlands contain na rich waters that vary widely in electrical conductivity as high as 159 ms cm and in ionic composition but local spring waters are extremely dilute basin floors exhibit a unique type of microrelief which appears to form by the filling of microlows with water and the dispersal of soil material therein by na followed by dewatering and collapse of the soil with drying illite dominates basin surface soils but smectite dominates at depth high soil ph available k and frequent wetting drying cycles in the wetlands suggest that in situ illitization may have occurred soil crusts and vesicular surface horizons are common as are upward increases in electrical conductivity the activity of sulfate reducing microbes forms prominent near surface horizons of sulfate reduction in saturated soils which retract or disappear entirely during dry episodes saline sodic wetland soils in the study area change on daily to seasonal scales cycles of surface salt development microbial activity and microrelief genesis are all controlled by regular wetting drying cycles and the interaction of ponded surface waters and shallow groundwaters relatively unique aspects of microbial ecology and surface processes make the soils important as geomicrobial reactors wherein important parts of hydrological and geochemical cycles occur

devonian tetrapod trackways and trackmakers a review of the fossils and footprints abstract the earliest tetrapods are known from the upper devonian their remains are becoming better known from increasing numbers of specimens localities environments and ichnofossils each of the eight or possibly nine genera now represented by skeletal fossils is reviewed in its sedimentological faunal and stratigraphic context with an assessment of what might be inferred about the habitus and locomotory capabilities of each fossil trackways and their interpretations are then re examined in the context of the known body forms and consideration given to the degree of fit between the skeletal fossils the trackways and their interpretations the currently known devonian tetrapods are unlikely to have made any of the known tracks unless they were produced under water neither the skeletal fossils nor the trackways show good evidence of terrestrial locomotion among devonian tetrapods when the fossil material and recent phylogenetic analyses are taken in combination it appears that neither tetrapods nor limbs with digits are likely to have arisen before the frasnian this should be borne in mind in palaeoecological studies of these animals

the early carboniferous courceyan arundian monsoonal climate of the british isles evidence from growth rings in fossil woods the british isles lay at a palaeolatitude of 4 s during the early carboniferous courceyan arundian period this paper examines fossil gymnosperm wood from ten localities in western ireland and southern scotland in order to analyse palaeoclimate fifty two percent of the 77 fossil wood specimens studied exhibit growth rings that possess subtle discontinuous ring boundaries and ring increments of narrow but variable width these growth rings are qualitatively and quantitatively analysed and are shown to bear a close similarity to growth rings in modern araucarian conifer woods these araucarian growth rings are formed in response to tropical rainfall seasonality linked to monsoonal circulation the findings of this study therefore support earlier palaeoclimatic interpretations based on sedimentological evidence which suggest that the british isles experienced a monsoonal climate during the early carboniferous courceyan arundian period

ferrolysis in arundian alluvial palaeosols evidence of a shift in the early carboniferous monsoonal system an unusual clay mineral assemblage from early carboniferous arundian palaeosols in south wales contains a three component kaolinite chlorite like material smectite mixed layer clay this is interpreted as the product of ferrolysis a complex process involving dissolution of clays a d the subsequent production of interlayered varieties from the repetitive reduction and reoxidation of iron compounds in seasonally waterlogged surface water grey soils support for this interpretation comes from the distribution of iron species iron concretions and vertic features in the palaeosol profile which indicate formation under strongly seasonal dry hydromorphic conditions the appearance of the ferrolytic pa iaeosol indicates a shi from a dry to a wet type monsoonal regime in late arundian times

do red beds indicate paleoclimatic conditions a permian case study abstract terrestrial red beds have long been interpreted as desert deposits by comparison with modern red deserts more recently red beds have been interpreted as evidence of seasonally dry conditions and a permo triassic pangean monsoon red beds of cala viola sardinia are identified as paleosols and used to reconstruct late permian paleoclimatic conditions reconstruction of paleoenvironmental conditions based on the paleosols of the cala viola indicates warm humid conditions with no evidence of dry conditions as in a desert or of extreme seasonality as in a monsoon instead it is suggested that the red color of the paleosols is a result of former good drainage and that red color in general does not indicate specific paleoclimatic conditions

transitional changes in arborescent lignophytes at the devonian carboniferous boundary abstract it is usually considered that after the extinction of the devonian tree archaeopteri s no new arborescent lignophytes were established before the late tournaisian a reassessment of this pattern is presented here based on a three fold approach a re evaluation of the taxic diversity of tournaisian lignophyte trees based on descriptions of new plants from palaeotropical latitudes a study of the patterns of phenotypic changes occurring among early lignophytes using a principal coordinate analysis and a phylogenetic analysis of the affinities of the arborescent taxa the best supported results indicate that a substantial taxonomic and phenotypic diversity of arborescent lignophytes was already established in the first part of the tournaisian including some taxa that persisted until the serpukhovian two genera may have originated in the late devonian and crossed the devonian carboniferous boundary fewer originations and a decrease in phenotypic diversity occurred in the visean the phenotypic distinctiveness of tree stems compared with those of other growth forms in the lignophytes is assessed we propose a scenario in which the presence of lignophyte trees is continuous across the devonian carboniferous boundary with arborescent taxa distinct from archaeopteris already present in the latest devonian possibly in upland floras and diversifying significantly soon after the devonian carboniferous boundary supplementary material a list of taxa characters and matrices used in the principal coordinate analysis and phylogenetic analysis is available at http www geolsoc org uk sup18447

early mississippian lycopsid forests in a delta plain setting at norton near sussex new brunswick canada mississippian lycopsid forests in growth position are extremely rare and their community scale ecology remains enigmatic this is a significant gap in our knowledge not least because they represent the precursors of pennsylvanian coal forests in this paper nearly 700 in situ fossil trees are described from 13 entisol or inceptisol horizons in the mid tournaisian albert formation horton group at norton near sussex new brunswick canada these trees almost all of which are lycopsids of the protostigmaria lepidodendropsis type are rooted mostly in the flood disturbed interdistributary wetland deposits of prograding wave dominated deltas tree mapping on extensive palaeosol surfaces indicates the existence of extremely dense forest vegetation scaled up to standard forestry units densities of 10 000 30 000 trees per hectare are inferred a significant inverse linear relationship between tree diameter and density for the five most extensive palaeosols indicates that inter tree competition led to natural self thinning as the forests matured forest maturation also led to a reduction in tree spacing heterogeneity flood events regularly killed whole stands at norton burying trees in sandstone sheets and preventing establishment of climax vegetation charcoal remains demonstrate that wildfire was another important disturbance process

paleosol classification problems and solutions abstract paleosols are soils that formed on landscapes of the geologic past three kinds exist buried exhumed and relict to help reconstruct paleoenvironments and for ease of comparison we suggest a property based classification system linked to genetic processes we use enduring properties because alteration of paleosols following burial is common morphological properties such as horizonation soil fabric root and worm casts and redoximorphic features are resistant to alteration and thus are valuable as criteria field observable and micromorphological properties degree of weathering and proportion of resistant minerals are also useful as criteria for paleosol orders total chemical analysis provides a proxy measure for base saturation and clay mineralogy we use proxy criteria to help classify paleosols that have changed markedly or have been lithified during or after burial to an earlier version of the system we add two new orders and include buried relict lithified and exhumed units at the suborder level our system clearly separates paleosol taxon names from those of all ground soils we use the prescript paleo at the order level and kryptic to designate the buried enduric to designate the relict lithic to designate the lithified and emergent to designate the exhumed paleosol suborders we use prescript modifiers to describe the physical characteristics of the paleosols and postscripts for parent material origin and the extensiveness of the paleosol landscape we present data and classify a number of paleosols as examples of the system

mass balance reconstruction of a modern vertisol implications for interpreting the geochemistry and burial alteration of paleo vertisols abstract utilizing identical sampling and analytical techniques the morphological and chemical characteristics of a modern vertisol houston black series central texas can be directly compared with an upper mississippian paleo vertisol from the appalachian basin pennington formation east central tennessee mass balance reconstructions suggest retention of primary pedochemical patterns in the paleo vertisol including patterns of soil volume change strain and transport functions translocations of many major and trace elements retention of primary pedochemical patterns suggests that vertisols constitute nearly closed systems during burial diagenesis chemical and mineralogical changes associated with burial diagenesis of the paleo vertisol include oxidation of organic carbon oc illitization of smectites dehydration and recrystallization of fe mn oxyhydroxides and dolomitization of pedogenic calcite significant differences in the chemical behavior of gilgai microhigh and microlow pedons in modern vertisols have implications for interpretation of geochemical data obtained from paleo vertisols overall wetter soil conditions and variable redox potential under gilgai microlows promote greater depths of leaching and mobility of redox sensitive trace elements including co cr cu mn ni and v gilgai microhighs behave as evaporative wicks that draw moisture and soluble phases towards the soil surface resulting in precipitation of metal hydrosylate complexes and sulfates gypsum at the capillary fringe and shallower depths of leaching and fixation of trace elements paleoprecipitation estimates from paleosols based on the depth to the top of the pedogenic carbonate horizon should therefore utilize field petrographic and geochemical data for characterizing maximum depths of leaching loss or gain of exchangeable bases and calcification rather than relying solely upon field data

tetrapod trackways from the early middle devonian period of poland the fossil record of the earliest tetrapods vertebrates with limbs rather than paired fins consists of body fossils and trackways the earliest body fossils of tetrapods date to the late devonian period late frasnian stage and are preceded by transitional elpistostegids such as panderichthys and tiktaalik that still have paired fins claims of tetrapod trackways predating these body fossils have remained controversial with regard to both age and the identity of the track makers here we present well preserved and securely dated tetrapod tracks from polish marine tidal flat sediments of early middle devonian eifelian stage age that are approximately 18 million years older than the earliest tetrapod body fossils and 10 million years earlier than the oldest elpistostegids they force a radical reassessment of the timing ecology and environmental setting of the fish tetrapod transition as well as the completeness of the body fossil record

palaeocene eocene paratropical floral change in north america responses to climate change and plant immigration the initial eocene thermal maximum ietm at c 55 ma represents a period of rapid global warming that lasted less than 200 ka the response of vegetation to such an event and particularly warm adapted highly diverse vegetation types is poorly understood using pollen floral clay mineral and stable carbon isotope analyses of sediments from the upper tuscahoma formation on the eastern us gulf coast eastern mississippi and western alabama we document paratropical floral changes across the palaeocene eocene boundary from the wahalak 2 and lower harrell cores data indicate strong changes in the abundance of kaolinite that correlate with changes in relative abundance of native pollen taxa there is no evidence for a transient extra tropical flora on the us gulf coast that may characterize the ietm immigration and extinction are not associated with this event instead early eocene plant immigration occurs in pulses and therefore is not associated directly with climate change during the ietm the two cores share the same regional species pool but compositional differences are stronger between cores than they are either through changes in environment increased soil erosion or chemical weathering or through the introduction of non native plants our data suggest that vegetation change across the palaeocene eocene boundary is not a single event but rather a sequence of cascading events

highly structured tropical airglow and tec signatures during strong geomagnetic activity a remarkable set of all sky images using the 630 nm airglow emission has been taken over the arecibo observatory in puerto rico wave like structures at a height of about 250 km are commonly found to travel in the southwest direction at speeds ranging from 20 120 m s most surprising is that geomagnetic activity seems to greatly amplify them forming very intricate patterns of light and dark simultaneous observations using gps satellite transmissions on one night reveal that dark regions are severely plasma depleted while bright regions have nighttime content as large as the full noontime ionosphere this unexpected geomagnetic effect at mid latitudes has implications for trans ionospheric radiowave propagation and space weather

the anatomy of an early dinantian terraced floodplain palaeo environment and early diagenesis the lowermost carboniferous rocks in the cockburnspath area of east berwickshire southern scotland are interpreted as coastal floodplain sediments a lower mudstone dominated unit is composed of silty mudstones and shales with subordinate sandstones and argillaceous ferroan dolomites cementstones these are interpreted as distal floodplain sediments with periodic crevasse splay deposition the dark grey colour of the mudrocks suggests deposition in reducing conditions probably in floodplain lakes most of the cementstones are concretionary some with septarian cracks suggesting an early diagenetic origin an immature palaeosol suggests periodic pedogenesis under improved drainage a synsedimentary erosion surface indicates incision of a valley into the floodplain presumably in response to base level lowering an upper sandstone dominated unit starts with fine grained rippled sandstones cut by small channel sandstones these are interpreted as floodplain lake deposits fed by crevasse channels a distinctive conglomerate with cementstone clasts wood fragments and fish remains is interpreted as a major overbank deposit dumped into a pre existing floodplain lake a bivalve fauna was established in the overlying mudstones followed by a thin limestone with a restricted marine fossil assemblage showing that seawater flooding of the lakes occurred at times mudrocks throughout the sequence contain no pyrite except for the marine band which has an organic carbon sulphur ratio and degree of pyritization value typical of marine sediments the concretionary cementstones have d13c values around 4 to 6 0 00 pdb which are interpreted as indicative of anaerobic oxidation of organic matter the combined geochemical data suggest a significant involvement of iron reduction in cementstone formation although the d13c values are ambiguous in assessing the relative involvement of methanogenesis and methane oxidation limited seawater inundation of the floodplains might have supplied magnesium and calcium ions for dolomite formation assuming that any h2s derived as a result of sulphate reduction was oxidized by iron reduction alternatively a weathering source for solutes might have been involved

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

vitrinite reflectivity and the structure and burial history of the old red sandstone of the midland valley of scotland vitrinite reflectivities from lower old red sandstone ors sediments of the strathmore region in the midland valley of scotland give values of 1 2 for the stonehaven group kincardineshire 0 9 for the arbuthnott group angus and 1 3 for the strathmore group perthshire these values are corroborated by clay mineral diagenesis studies the stonehaven group reflectivity values are considerably lower than expected under the 9 km thickness of sediments aggregated for the lower old red sandstone of kincardineshire and demonstrate a maximum burial of some 3 to 5 km these results together with detailed vitrinite reflectivity measurements in the dundee formation consideration of post devonian burial history and kinetic burial modelling show that the present level of lower ors thermal maturation results from late carboniferous maximum burial this is confirmed by comparison with a vitrinite reflectivity gradient from the strathclyde group of fife to reconcile the vitrinite reflectivity data with the stratigraphy and structure of the lower old red sandstone burial models invoking structural repetition depocentre migration and structurally assembled stratigraphy are considered it is concluded that the lower old red sandstone is a structurally assembled series of basins with the cowie formation of the stonehaven group being part of a separate depositional succession and structurally juxtaposed into its present position as part of an apparently contiguous sequence

pedogenic translocation of fe in modern and ancient vertisols and implications for interpretations of the hekpoort paleosol 2 25 ga abstract many interpretations of oxygen levels in the precambrian atmosphere use interpretations of fe distributions measured in paleosols this article addresses the current lack of knowledge concerning baseline fe translocations in modern soil analogs for the 2 25 ga hekpoort paleosol at waterval onder south africa as well as the lack of understanding of diagnostic petrographic features related to fe translocation preserved in the precambrian paleosols petrographic features related to fe translocations include redox related fe depletions and enrichments and possibly fe mn nodules which compare favorably with similar pedogenic features in paleozoic paleo vertisols and modern analog vertisols additionally preservation of sepic plasmic microfabrics in the hekpoort paleosol which are characteristic of clay soils experiencing shrink swell supports previous paleo vertisol interpretations total fe losses in vertisols are 10 50 losses increase with increasing soil age and with increasing mean ann

seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central new mexico usa in order to better calibrate pedogenic carbonate as a proxy for past environments we compared the stable isotopic composition of soil co 2 soil water and pedogenic carbonate in young soils from central new mexico usa seasonal changes in the 13 c value of soil co 2 the 18 o value of soil water and the soil temperature were monitored to establish the timing of isotopic equilibrium with the carbonate calcite solubility was calculated from measured temperatures and co 2 concentrations in the soil this approach allowed us to determine the conditions associated with pedogenic carbonate formation carbon isotope equilibrium oxygen isotope equilibrium and minimum calcite solubility all occurred simultaneously during warm dry conditions in may 2008 when soil co 2 concentrations were low it is therefore concluded that pedogenic carbonate forms during warm dry periods and does not record mean growing season conditions as typically assumed the seasonal bias in pedogenic carbonate formation may explain the occurrence of pedogenic carbonate in monsoon climates and its absence in regions where annual precipitation is more uniformly distributed the implications of the seasonal bias for stable isotope based paleoenvironmental reconstructions are that paleoelevations may have been previously over or underestimated paleoatmospheric co 2 concentrations likely have been signifi cantly overestimated and pedogenic carbonate provides a c 4 biased record of paleovegetation especially in dry soils

a wrb based buried paleosol classification abstract present classification systems for buried paleosols are inadequately developed several classification systems for paleosols based on the us soil taxonomy have been developed recently but their use is still very limited we propose appilcation of the world reference base for soil resources which uses only substantial profile characteristics as a background for the development of a new buried paleosol classification the system was adapted for the use for buried paleosols dynamic criteria which could be altered by diagenesis were disregarded and the definitions of most horizons were modified a new prefix infra was applied for modified diagnostic horizons and properties and for refernce groups of buried paleosols as a result 11 diagnostic horizons 2 properties and 2 materials were left with their definitions and names 9 diagnostic horizons and 2 properties were modified and named with the prefix infra 14 diagnostic horizons 6 properties and 4 materials were excluded or joined with others and two new diagnostic horizons were proposed this relationship reflects the balance between stable and dynamic properties in the diagnostic criteria used by the wrb the number of soil units proposed for buried paleosols is fewer than for surface soils in the wrb 25 instead of 30 the use of wrb modifiers reflecting dynamic soil properties was tentatively recommended for the second level buried paleosols classification with prefixes pedo for pedogenically derived properties and dia for the properties caused by post burial processes the application of the proposed system to a set of paleosols previously described in the literature showed its utility for buried paleosol classification

evolution of the freshwater ecosystem the fossil record abstract the freshwater ecosystem may be as old as most life although freshwater life is taxonomically impoverished in comparison with marine and terrestrial biotas and ultimately derived from them it cannot be assumed that freshwater communities have necessarily been less complex in the geologic past than they are today although it is clear they have undergone a number of major changes freshwaters contain not only their own ancient and peculiar groups some with ancestries as far back as the middle paleozoic but they have been a theater for adaptive radiation of more recent immigrants from the land or sea and a way station for still other groups that passed through both from sea to land and the reverse this review summarizes first fossil records in freshwaters for many of these organisms and examines the question of the changing complexity of the freshwater ecosystem through time by looking at the fossil record of continental aquatic habitats

the sedimentary environment of the late devonian east greenland tetrapods the late devonian early tetrapods in east greenland occur in the celsius bjerg group key occurrences are located in a detailed stratigraphic section used here to interpret the sedimentary palaeoenvironments the palaeoenvironment for the britta dal formation which contains both ichthyostega and acanthostega is reinterpreted the britta dal formation channels have flat bases are poorly channelized are of low sinuosity and are part of a very major distributory system that periodically experienced extreme flooding the tetrapod fossils were recovered from an ephemeral system that was not permanently habitable in the immediate area plant megafossils are poorly preserved casts and impressions dominated by lycopsids and fern like plants the overbank siltstones are dominated by arid soil forming processes and comprise a spectacular sequence of vertisols the 1174 m in situ ichthyostega locality in paralleldal was relocated and occurs just below the midpoint of the second megacycle in the britta dal formation

late devonian tetrapod habitats indicated by palaeosols in pennsylvania abstract late devonian famennian tetrapods from the duncannon member of the catskill formation near hyner pennsylvania usa have been found within palaeosols that offer a new line of evidence for their ancient environments hyner has yielded at least two fossil tetrapod species hynerpeton basseti and densignathus rowei subhumid vertisol palaeosols and semiarid aridisol palaeosols alternate at hyner as in other catskill formation sedimentary cycles attributed to milankovitch eccentricity periods 100 ka tetrapods were found in palaeosols of subhumid not semiarid phases of 100 ka palaeoclimate cycles in addition palaeosols at hyner record an unusually warm and wet climatic episode compared with other palaeosols of the catskill formation and correlated with the european annulata black shale event tetrapod bones are cracked and disarticulated in red palaeosols of an oxbow lake margin as if victims of dry season death decay and subaerial weathering vegetation choked swales and floodplains would have afforded shelter from 3 4 m long predatory fish hyneria lindae of open water and offered food of large dead fish small live fish arachnids myriapods and scorpions if these early tetrapods lived on land at all it was during wet seasons of feeding and breeding rather than fatally dry seasons supplementary material chemical data are available at http www geolsoc org uk sup18373

woodland hypothesis for devonian tetrapod evolution abstractthe rarity of devonian tetrapods and the absence of tetrapods during the first 14 million years of the mississippian romer s gap have inspired hypotheses of fish tetrapod evolutionary transition as an escape from difficult habitats such as deserts or stagnant waters these hypotheses and romer s gap are tested here using depth to calcic horizon in paleosols of the northern appalachians as a proxy for precipitation and vegetation changes during the devonian and mississippian all tetrapod bones and trackways in this region as well as fossil tree remains were found at times of high precipitation indicated by deep calcic paleosols when subhumid woodlands expanded at the expense of semiarid shrublands in alluvial lowlands no tetrapods or tree fossils were found in abundant paleosols with the shallow calcic horizons of aridland soils the mean annual precipitation requirement of devonian mississippian tetrapods and trees was at least mm global distribution of prototetrapods and aquatic tetrapo

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

preservation of a paleo vertisol and an estimate of late mississippian paleoprecipitation abstract a late mississippian paleosol satisfying all of the morphological criteria required for classification of holocene vertisols provides quantitative paleoclimate information in addition to the now commonplace interpretation of precipitation seasonality based on the presence of vertic features paleoprecipitation was estimated using the empirical relationship between depth to pedogenic carbonate horizon in quaternary soils burial compaction erosional truncation and high paleoatmospheric co2 concentration all factors that complicate paleoprecipitation estimates are unusually well constrained for this paleosol allowing for 10 compaction the paleosol had a pre burial depth of 100 cm for the pedogenic carbonate horizon yielding a mean annual paleo precipitation estimate f 648 141 mm this is comparable to the mean annual precipitation for brownsville texas where similar soils are found today a dolomicrite crust developed in gilgai microlows is well preserved in the paleo vertisol higher late mississippian paleotemperatures and rates of evapotranspiration associated with a lower latitude paleogeography for central tennessee during the late mississippian may explain in part why holocene coastal vertisols in the brownsville region lack surficial crusts similar to that of the paleo vertisol we qualitatively define the late mississippian climate of central tennessee as semiarid

evaluating the use of weathering indices for determining mean annual precipitation in the ancient stratigraphic record abstract different quantitative methods have been developed to determine paleo rainfall using paleosols of particular interest are methods that use bulk geochemistry to calculate a weathering index and from that mean annual precipitation twenty three paleosols that formed during a time of significant climate change the paleocene eocene thermal maximum petm were analyzed to evaluate the relative merits of two geochemical proxies that have been developed for estimating paleoprecipitation one depends on the chemical index of alteration without potash cia k and the other uses the calmag weathering index which depends on cao and mgo the paleosols are located in the paleogene fort union and willwood formations in the bighorn basin wy morphologic differences among the paleosols indicate that they formed under varied soil moisture conditions a morphology index was developed from pedogenic features that are sensitive to soil drainage and thus to rainfall to assess that variability quantitative mean annual precipitation map values were calculated for each paleosol using the cia k index and the calmag index which was developed specifically for vertisols those results were compared to the morphology index for 23 paleosols the results indicate that increases and decreases in map calculated from both methods correlate relatively well to changes in the soil morphology index however the results from the calmag weathering index show a stronger correlation the results suggest that the calmag proxy provides a more robust map estimate for vertisols in addition to comparing map estimates to the soil morphology index we compared the map values to paleorainfall estimates determined from paleofloras at the same stratigraphic levels as three of the paleosols that comparison confirms that the calmag method is reliable for reconstructing map from ancient vertisols the results also show that in the bighorn basin vertisols with a b horizon

palaeoenvironments of the eifelian dolomites with earliest tetrapod trackways holy cross mountains poland abstract the eifelian dolomites in the zachelmie quarry holy cross mountains poland contain trackways and tracks of tetrapods 390 391 ma old and thus the oldest known so far the environments of the trackway bearing beds have been investigated using sedimentological palaeontological geochemical and palaeomagnetic methods the reconstructed tetrapod habitats comprised shallow water lagoons separated from an open marine basin by sparsely vegetated islands and spits the lagoonal waters were well aerated and a few metres deep at most undergoing periodic desiccation the dolomitic sediments primarily of microbial origin formed in tropical waters of slightly modified marine composition oxygen isotope data obtained from the dolomicrites suggest water temperatures around 30 c the seasonal semi arid to sub humid climate deduced from paleosol characteristics was probably of a tropical monsoonal type the degree of restriction of the lagoonal system evolved from relatively open evaporation dominated towards increasingly closed freshwater influenced the detailed observations of the footprint bearing beds as well as the characteristics of the tracks indicate that they were formed mostly under subaqueous conditions by wading walking on the bottom or swimming animals lack of tidal indicators in the restricted zachelmie lagoons argues against previous concept that tidal flats served as a food source for the early tetrapods nor is a hypothesis of flooded woodlands confirmed as a habitat promoting the fish to tetrapod transition we propose that functional limbs emerged among aqueous animals that acquired their locomotional capabilities in a shallow lagoonal water before attempting longer excursions on land

ecology and evolution of devonian trees in new york usa abstract the first trees in new york were middle devonian earliest givetian cladoxyls duisbergia and wattieza with shallow rooted manoxylic trunks cladoxyl trees in new york thus postdate their latest emsian evolution in spitzbergen progymnosperm trees svalbardia and callixylon archaeopteris appeared in new york later mid givetian than progymnosperm trees from spitzbergen early givetian associated paleosols are evidence that wattieza formed intertidal to estuarine mangal and callixylon formed dry riparian woodland also from paleosols comes evidence that wattieza and callixylon required about 350 mm more mean annual precipitation than plants of equivalent stature today that wattieza tolerated mean annual temperature 7 c less than current limits of mangal 20 c and callixylon could tolerate temperatures 14 c less than modern mangal devonian mangal and riparian woodland spread into new york from wetter regions elsewhere during transient paleoclimatic spikes of very high co 2 3923 238 ppmv and subhumid mean annual precipitation 730 147 mm conditions which were more likely extrinsic atmospheric perturbations rather than consequences of tree evolution for most of the middle devonian co 2 was lower 2263 238 ppmv and paleoclimate in new york was semiarid mean annual precipitation 484 147 mm such transient perturbations and immigration events may explain the 40 million year gap between the late emsian 400 ma evolution of trees and famennian 360 ma co 2 drawdown and expansion of ice caps

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

goethite calcite and organic matter from permian and triassic soils carbon isotopes and co2 concentrations abstract pedogenic goethites in each of two early permian paleosols appear to record mixing of two isotopically distinct co2 components atmospheric co2 and co2 from in situ oxidation of organic matter the 13c values measured for the fe co3 oh component in solid solution in these permian goethites are 13 5 for the lower leonardian 283 ma bp paleosol mcgoeth and 13 9 for the upper leonardian 270 ma bp paleosol sap these goethites contain the most 13c rich fe co3 oh measured to date for pedogenic goethites crystallized in soils exhibiting mixing of the two aforementioned co2 components 13c measured for 43 organic matter samples in the lower leonardian waggoner ranch fm has an average value of 20 3 1 1 1s the average value yields a calculated early permian atmospheric p co 2 value of about 1 pal but the scatter in the measured 13c values of organic matter permits a calculated maximum p co 2 of 11 pal pal present atmospheric level measured values of the mole fraction of fe co3 oh in mcgoeth and sap correspond to soil co2 concentrations in the early permian paleosol profiles of 54 000 and 50 000 ppmv respectively such high soil co2 concentrations are similar to modern soils in warm wet environments the average 13c values of pedogenic calcite from 9 paleosol profiles stratigraphically associated with mcgoeth waggoner ranch fm range from 6 5 to 4 4 with a mean 13c value for all profiles of 5 4 thus the value of 13c between the pedogenic calcite data set and mcgoeth is 8 1 0 9 which is in reasonable accord with the value of 7 7 expected if atmospheric p co 2 and organic matter 13c values were the same for both paleosol types furthermore the atmospheric p co 2 calculated for the early permian from the average measured carbon isotopic compositions of the paleosol calcite and organic matter is also analytically indistinguishable from 1 pal with a maximum calculated atmospheric p co 2 permitted by one standard deviation of the organic matter 13c value of 5 pal if however measured average 13c values of the plant organic matter are more positive than the original soil organic matter as a result of diagenetic loss of 13c depleted labile organic compounds calculated permian atmospheric p co 2 using these 13c enriched organic values would underestimate the actual atmospheric p co 2 using either goethite or calcite this is the first stratigraphically constrained intrabasinal study to compare ancient atmospheric co2 concentrations calculated from pedogenic goethite and calcite these results demonstrate that the two different proxies record the same information about atmospheric co2 the fe co3 oh component in pedogenic goethite from a triassic paleosol in utah is significantly enriched in 13c relative to fe co3 oh in goethites from soils in which there are mixtures of two isotopic co2 components field relationships and the 13c value 1 9 of the triassic goethite indicate that this ancient paleosol profile experienced mixing of three isotopically distinct co2 components at the time of goethite crystallization the three components were probably atmospheric co2 co2 from in situ oxidation of organic matter and co2 from in situ dissolution of preexisting calcite although mixing of three isotopically distinct co2 components as recorded by fe co3 oh in goethite has been described in modern soil this is the first example from a documented paleosol its preservation affirms the need for careful case by case assessment of ancient paleosols to establish that goethite in any particular soil is likely to be a valid proxy of atmospheric p co 2

the terrestrial landscapes of tetrapod evolution in earliest carboniferous seasonal wetlands of se scotland abstract the lower mississippian tournaisian ballagan formation in se scotland yields tetrapod fossils that provide fresh insights into the critical period when these animals first moved onto land the key to understanding the palaeoenvironments where they lived is a detailed analysis of the sedimentary architecture of this formation one of the thickest and most completely documented examples of a coastal floodplain and marginal marine succession from this important transitional time anywhere in the world palaeosols are abundant providing a unique insight into the early carboniferous habitats and climate more than 200 separate palaeosols are described from three sections through the formation the palaeosols range in thickness from 0 02 to 1 85 m and are diverse most are entisols and inceptisols 63 indicating relatively brief periods of soil development gleyed inseptisols and vertisols are less common 37 vertisols are the thickest palaeosols up to 185 cm in the ballagan formation and have common vertic cracks roots are abundant through all the palaeosols from shallow mats and thin hair like traces to sporadic thicker root traces typical of arborescent lycopods geochemical isotope and clay mineralogical analyses of the palaeosols indicate a range in soil alkalinity and amount of water logging estimates of mean annual rainfall from palaeosol compositions are 1000 1500 mm per year the high mean annual rainfall and variable soil alkalinities contrast markedly with dry periods that developed deep penetrating cracks and evaporite deposits it is concluded that during the early carboniferous this region experienced a sharply contrasting seasonal climate and that the floodplain hosted a mosaic of closely juxtaposed but distinct habitats in which the tetrapods lived the diversification of coastal floodplain environments identified here may link to the evolution and movement of tetrapods into the terrestrial realm

significance of different modes of rhizolith preservation to interpreting paleoenvironmental and paleohydrologic settings examples from paleogene paleosols bighorn basin wyoming u s a abstract different modes of preservation of root traces rhizoliths provide information on soil moisture regimes in alluvial paleosols in the paleogene fort union and willwood formations of the bighorn basin wyoming u s a this paper links different styles of rhizolith preservation to paleosols whose other pedogenic attributes provide information on ancient soil drainage consequently the paleodrainage significance of different rhizolith preservation patterns is established more confidently rhizoliths consisting of elongate gray mottles rhizohaloes with red rims are common in relatively well drained red paleosols the gray zones are depleted of iron fe whereas the color of the rims indicates hematite accumulation these features are typical of surface water gley processes that caused fe and manganese mn to move from the root channel outward to the soil matrix calcareous rhizocretions either calcareous tubular concretions or micro accumulations of carbonate within gray rhizotubules are also common in moderately well drained red paleosols more poorly drained purple paleosols also have rhizoliths consisting of fe depletion zones however the rhizohaloes are surrounded by yellow brown goethite rims rather than red hematitic rims in many paleosols the red and yellow brown accumulation rims were partly removed by continued depletion producing abundant irregular shaped mottles the nature of the rhizohalo and the color of the fe oxide rim provide information about the intensity of gleying that a paleosol underwent the poorly drained paleosols also show rhizoliths preserved as goethite accumulations contained within gray depletion zones indicating movement of reduced fe from the matrix towards the root channel probably as a result of groundwater gley processes the goethite accumulations are intermingled locally with lignite representing preservation of the root organic material some rhizoliths are preserved as tube shaped concentrations of small 0 1 0 2 mm diameter black spheres whose color indicates a mix of mn and fe oxides these are most common in paleosols with low chroma gray matrix colors indicating very poor drainage the very poorly drained paleosols also show rhizoliths preserved in jarosite which is an oxidation product of pyrite careful observational and geochemical analysis of rhizoliths which are common in continental deposits can help produce a clearer and more thorough interpretation of ancient drainage conditions information about degree of ancient soil wetness or moisture is important for understanding past climatic conditions and for reconstructing terrestrial paleolandscapes

a stochastic basis to the spatially uniform distribution of randomly generated ionian paterae due to its tidally heated interior io is a geologically very active satellite that bears many volcanic features it is observed that the mean nearest neighbor distance of each volcanic feature called a patera is larger than that of a random distribution which implies that the spatial distribution of paterae is uniform rather than random however it is uncertain how the paterae are organized into a uniform distribution we suggest the mechanism of io s uniformly distributed paterae considering localized obliteration of old features instead of geological modeling we performed stochastic simulations and statistical analyses for the obliteration of quiescent paterae monte carlo calculations with gaussian obliteration probability show that if the width of obliteration probability is approximately 80 km and the volcanic generation rate is 5 0 10 6 km 2 ma 1 uniform distribution and the observed number density of paterae are attained at the 2 level on a timescale of approximately 6 million years with this generation rate and width of the obliteration probability the averaged distance of one patera to the nearest patera mean nearest neighbor distance is approximately 200 km which is consistent with the observed value the uniformity of the distribution is maintained once it is achieved on regional scales io s paterae would naturally evolve from random into uniform distributions by the obliteration of old and quiescent features

pedogenic carbonates as a proxy for palaeo co2 in the palaeozoic atmosphere abstract according to a model by cerling cerling t e 1991 carbon dioxide in the paleoatmosphere evidence from cenozoic and mesozoic paleosols am j sci 291 377 400 cerling t e 1999 stable carbon isotopes in palaeosol carbonates in thiry m simon coincon r eds palaeoweathering palaeosurfaces and related continental deposits vol 27 of spec publ int assoc sediment pp 43 60 the carbon isotope composition of calcretes should depend on the soil type and the co 2 concentration in the atmosphere we have tested cerling s model by investigating 14 palaeozoic sections with soil profiles a large number of carbonate types of different genetic origin exist in the localities examined comparing the palaeozoic samples with recent and subrecent calcretes it can be demonstrated that anhedral cryptocrystalline 2 concentration

paleoclimate and the global distribution of paleosols a theoretical model is developed for the relationship between paleoclimate and paleosols for the time interval following the widespread appearance of vascular land plants the model defines four paleoclimatic zones 1 a wet equatorial zone primarily characterized by oxisols and secondarily by argillisols and histosols 2 a subtropical dry zone containing calcisols and less commonly gypsisols and vertisols 3 a moist mid latitude zone with argillisols spodosols gleysols and histosols and 4 a polar zone featuring protosols and gleysols the model is general in nature and its application to the geologic past will be affected by variability through time in paleogeography and paleoclimatic parameters

fluvial sedimentation in the lower carboniferous of clew bay county mayo ireland abstract a succession of about 300 m of fluvial sediments from the lower carboniferous of northwest ireland is described and interpreted a lower mainly red formation contains fluvial channel deposits dominated by flat laminated sandstone these are separated by interbedded sandstones and mudrocks with local caliche horizons and abundant mudcracks interpreted as levee and flood basin deposits an upper mainly non red formation contains fluvial channel deposits with common trough cross stratification and epsilon cross stratification also separated by interbedded sandstones and mudrocks evidence of desiccation is less common in the uppermost beds which pass transitionally upwards into marine sediments the change in fluvial channel style is interpreted as due to increasing sinuosity and permanence of flow which may have been partly temporally and partly spatially controlled the predominance of coarse sediments is thought to be largely controlled by limited subsidence the lower carboniferous transgression was the major overall control of alluviation

multiproxy approach reveals evidence of highly variable paleoprecipitation in the upper jurassic morrison formation western united states elemental analyses of paleosol b horizons in the upper jurassic morrison formation of the western united states provide estimates of mean annual precipitation map and allow determination of humidity regimes samples were collected from the lower morrison formation in new mexico and the upper morrison formation in wyoming and montana the chemical index of alteration minus potassium cia k and the calcium and magnesium weathering index calmag were used to estimate paleorainfall cia k values calculated for paleosols without shrink swell vertic features correspond to map estimates between 800 and 1100 mm yr 1 with an average of 1000 mm yr 1 calmag values calculated for vertic paleosols correspond to map estimates between 50 and 1200 mm yr 1 with an average of 700 mm yr 1 map estimates from the older new mexico strata indicate that early morrison environments were relatively arid map estimates from the younger wyoming and montana deposits reflect wetter conditions in the northernmost part of the morrison formation but the transition from arid interior environments was abrupt humidity provinces inferred from geochemical proxy based estimates of evapotranspiration and energy influx from precipitation range from semiarid to superhumid suggesting wetter conditions than the map estimates but supporting the relative differences in moisture among the three study areas paleoprecipitation patterns within the morrison depositional basin do not match the modern latitudinal distribution of rainfall that arises from zonal atmospheric circulation comparison with the upper jurassic lourinha formation in portugal and the vega formation in spain reveals that map in late jurassic portuguese environments was similar to that in the wet northern part of the morrison formation although more arid conditions prevailed in some areas of portugal inferred humidity regimes for the lourinha formation which range from semiarid to superhumid also indicate small scale geographic variability in climate although less pronounced than that observed in the morrison formation paleoenvironments in northern spain were similar to the drier morrison environments in the continental interior given the abrupt climatic transitions inferred here for the morrison formation paleoprecipitation estimates derived from a geographically restricted sample may reflect only local conditions and should not necessarily be extrapolated to larger areas

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

implications on the paleoecology of autochthonous lycopods in clastic sedimentary environments of the early pennsylvanian of alabama abstract numerous correlative localities throughout the upper cliff coal interval lower pennsylvanian blount county alabama have been observed in which lycopod forests are preserved these assemblages are present in lower delta plain facies interpreted to represent 1 the abandonment phase of a distributary channel system with resultant bayou development 2 non peat accumulating swamps capping interdistributary bay deposition 3 possible terminal phase of peat accumulating swamps and 4 crevasse splay deposits field observations in combination with sedimentological preservational and biological evidence support the conclusion that these autochthonous carboniferous lycopods represent a taphonomically biased assemblage of aquatic or semi aquatic swamp communities interpretations derived from the present study in conjunction with published accounts of erect lycopods suggest that these plants could tolerate all waters from fresh to saline conditions periodic drying of swampy habitats may have subjected lycopods to subaerial and aerial conditions but bulk replaced erect lycopods predominantly inhabited water stressed conditions the monotypic character of the lycopod forests supports the hypothesis that in the tropical lowlands of the tropical lowlands of the carboniferous lycopods held a relatively unique physiologically stressed position in the delta flood basin these arborescent lycopods became established in any depositional site subject to flooding and standing water when conditions prevailed which allowed for the establishment and development of individuals

a classification system for buried paleosols abstract paleosols formed on prior surfaces of the geologic past and include buried exhumed and relict kinds exhumed and relict ones are subaerial and have been classified according to systems of classification for other soils at this interface one of these systems soil taxonomy includes relict and exhumed paleosols with the subaerial ground soils but would need extensive modification to include buried paleosols our approach to paleosol classification like that of the recently published mack james monger system uses some soil taxonomy orders however we use proxy criteria to incorporate plaeosols that have become lithified and add the prefix krypt hidden or covered to all order names enduring properties are used as proxy criteria because base saturation by the nh4oac method and cementation of paleosols tends to increase with additions of salt gypsum and carbonate to buried paleosols we chose as proxy criteria the weatherable mineral content of sands and silts cation exchange capacity nh4oac method to clay ratio total analysis of the