phytoplankton associations of the anisian peri tethys basin central europe evidence of basin evolution and palaeoenvironmental change abstract anisian lower muschelkalk phytoplankton associations of the nw tethys shelf and the northern peri tethys basin are characterized by acritarchs and prasinophytes stratigraphical and lateral variations in the distribution pattern of these phytoplankton groups were analyzed in key sections of the central basin germany the southern gate areas switzerland poland and the northwestern tethys shelf hungary with the aim to infer palaeoenvironmental changes related to the basin evolution stratigraphically maximum abundance of marine phytoplankton is recognized during phases of maximum flooding laterally a dominance of different phytoplankton groups within these intervals is documented in the central part of the basin prasinophytes reach 80 percent of the total plankton association sediments of the basin margin the gate areas and proximal shelf show high amounts of acritarchs ranging from 76 to 95 these signatures clearly reflect the basin evolution of the anisian lower muschelkalk peri tethys basin and the interaction between a restricted intracratonic basin and an open ocean generally the peri tethys basin is characterized by a stratified water column with oxygen depleted bottom waters and maximum abundance of prasinophytes during phases of transgression cooler waters from the shelf flood the restricted basin displayed in the acritarch dominated phytoplankton associations of the shelf and gate areas marginal parts of the basin are generally well oxygenated and dominated by acritarchs within the acritarch assemblage veryhachium spp is characteristic of the marginal and central parts of the basin whereas micrhystridium spp dominates shelf deposits and sediments of the gate areas respectively the present study highlights the significance of different phytoplankton associations in basin analysis and high resolution sequence stratigraphy

the carbon isotope shift at the permian triassic boundary in the southern alps is gradual carbon isotope ratios in marine carbonate rocks have been shown to shift at some of the time boundaries associated with extinction events for example cretaceous tertiary1 and ordovician silurian2 the permian triassic boundary the greatest extinction event of the phanerozoic3 is also marked by a large 13c depletion4 5 new carbon isotope results from sections in the southern alps show that this depletion did not actually represent a single event but was a complex change that spanned perhaps a million years during the late permian and early triassic these results suggest that the permian triassic p tr extinction may have been in part gradual and in part stepwise 6 7 but was not in any case a single catastrophic event

stratigraphic control and chronology of peat bog deposition in the serra do espinhaco meridional brazil abstract peat bogs consist of a heterogeneous substrate whose physical characteristics vary in accordance with botanical composition inorganic sediment content and the degree of organic matter om decomposition although rare in the tropical zone of south america they can form in places where temperature and drainage favor the accumulation of om due to the anoxic character of the environment om remains preserved providing a valuable record of the climate during its genesis in the serra do espinhaco bogs can be found buried under sand deposits and given the difficulty of mapping such deposits by conventional methods ground penetrating radar gpr was used in their location and the study of the relationship between peat bog genesis and bedrock setting gpr data revealed blocks of quartzite located perpendicular to the drainage pattern which are assumed to partially restrict the water flow and maintain wet conditions upstream favoring the development of hygrophilous vegetation and the accumulation of om radiocarbon dating showed that buried bogs are contemporary to the deeper parts of non buried peats and that there is a strong correlation between their stratigraphy and climatic conditions between 30 250 and 12 400 years before present bp the conditions were favorable for the accumulation of om between 12 400 and 7900 years bp erosive processes caused sand deposition in the depression favorable conditions for deposition of om resumed around 7900 years bp and lasted until about 3300 years bp over the past 2600 years the climate has been similar to the present with three brief periods favorable to om deposition

particle size fractionation of titanium and zirconium during weathering and pedogenesis of granitic rocks in nw spain abstract titanium and zr were analyzed in 10 weathering and pedogenetic soil profiles developed on granitic rocks from nw spain concentrations were obtained by xrf and the ti and zr bearing minerals were studied by petrographical sem and eds analysis both elements were measured in rock bulk soil and granulometric fractions sand 2000 50 m silt 50 2 m clay titanium concentrations in the rock varied between 0 5 and 4 2 g kg 1 and zr concentrations from 52 to 173 mg kg 1 concentrations in bulk soil for the different horizons remain almost unchanged and are strongly related to the element content of the parent rock in some epipedons ti content is relatively lower than that of the underlying horizons due to a dilution effect caused by the high organic matter content and the addition of fresh minerals from erosion upslope the mineralogical study revealed that zr is present exclusively in zircons while ti occurs in rutile ilmenite and titanite but mainly as a structural component of the biotite regarding the particle size fractions both elements behave differently zirconium is enriched in the silt fraction of all soil horizons with concentrations up to 5 times that of the parent rock while ti is enriched in the silt up to 5 times and clay fractions up to 12 times of the solum horizons and depleted in the sand fraction of the a horizons these results indicate that zr concentrations are mainly controlled by the abundance of zircons in the rock and their physical detachment from the host minerals upon weathering ti mainly depends on the release from the structure of biotites through chemical weathering and its reprecipitation as neoformed mineral phases this physicochemical fractionation of ti and zr in soils bears important implications for studies on soil genesis continuity of soil profiles and the calculation on enrichment factors which are based on the conservative behaviour of both elements

variations of organo mineral microfacies of posidonia shale from the lower saxony basin and the west netherlands basin application to paleoenvironmental reconstruction abstract high resolution organic petrological analysis has been carried out on core samples of the posidonia shale from four wells two located in northwestern germany lower saxony basin and two in the western netherlands west netherlands basin the organo mineral microfacies defined by maceral composition and associated mineral matter show a wide range of variations related to the proportions of individual liptinite macerals of marine origin and of terrestrial macerals macerals of vitrinite inertinite groups and sporinite variations in organo mineral microfacies in which the organic components are sensitive to paleoenvironmental changes are considered as a potential indicator of changes in depositional conditions sedimentation of organic matter is controlled by several factors the most important in the marine environment being primary biomass productivity and influx of transported terrestrial organic matter biological degradation related to bacterial activity and the oxygen content of the bottom water the level of degradation in organic rich sediments is mainly related to oxygen availability which in turn influences the diversity of algae and the quality and quantity of the preserved organic matter these two factors can be directly linked to maceral preservation and the organo mineral microfacies in order to evaluate the relationships between different types of organic matter and paleoenvironmental conditions two indices the oxidation index and the degradation index have been proposed these indices illustrate the transition from highly degraded to well preserved macerals provide information on the types of organic matter and permit recognition of precursors for degraded amorphous organic matter aom use of these indices not only enables determination of the organo mineral microfacies but also sheds light on the aom precursors in the posidonia shale information derived from the indices can also be used to reconstruct the paleoenvironments

holocene climate change in central eastern brazil reconstructed using pollen and geochemical records of pau de fruta mire serra do espinhaco meridional minas gerais abstract studies dealing with the reconstruction of holocene climate change of tropical areas are scarce of these multi proxy investigations using peatlands are still absent in this paper we present the holocene record of environmental changes in central eastern brazil reconstructed from a core sampled in pau de fruta mire serra do espinhaco meridional brazil we combined palynological and geochemical analyses supported by core stratigraphy 14 c dating and multivariate statistics the location of the mire is ideal because it is in an area which is directly associated with the south atlantic convergence zone sacz six main phases of change suggested by vegetation and local and regional landscape dynamics were described in phase i 10 000 7360 cal yr bp the climate was very wet and cold and was accompanied by soil instability in the mire catchment severe local erosion and the 8 2 ka event was easily recognizable by a large increase in the deposition of regional dust phase ii 7360 4200 cal yr bp was characterized by wet and warm conditions catchment soil stability and enhanced deposition of regional dust in phase iii 4200 2200 cal yr bp climate was dry and warm and soil erosion in the catchment increased again in phase iv 2200 1160 cal yr bp dry and punctuated cooling was reconstructed together with enhanced deposition of regional dust phase v 1160 400 cal yr bp reflects sub humid climatic conditions like the current climate the lowest inputs of local and regional dust and the largest accumulation of peat in the mire while in phase vi

stream aquifer interaction model with diffusive wave routing a practical approach to modeling the hydraulic interaction of a stream and aquifer via streambed leakage is based on the established u s geological survey usgs model modflow to represent flood wave propagation and the associated bank storage modflow s stream module is replaced by the muskingum cunge diffusive wave routing scheme the diffusive wave model closely approximates a dynamic model of a flood wave s speed shape and streambed leakage because the stream responds more rapidly to disturbances than the aquifer streambed leakage is calculated at the flood routing time scale in order to properly represent the stream aquifer coupling however both the relative magnitude and timing of aquifer response to a flood wave depend on the strength of this coupling we find discrepancies in both the flood wave and the streambed leakage when the wave and ground water motions are evaluated at different time scales these discrepancies are significant in the case of a strong stream aquifer coupling for which equal aquifer and flood routing time steps may be required wave diffusion and bank storage are shown to be comparable in magnitude and should therefore be included in stream aquifer interaction models diffusive wave routing more accurately represents wave propagation bed leakage and aquifer response if short aquifer time steps are taken and is preferable to the stream module for simulating short time transients however the stream module is useful for simulating large time frames if accurate modeling of the flood wave propagation is not required

permian triassic extinction organic δ13c evidence from british columbia canada the permian triassic p t extinction is documented geochemically in a marine sequence deposited in a basinal setting at williston lake northeastern british columbia by using elemental and isotopic organic geochemical data from well preserved sedimentary rocks the 13 c values of kerogens in the rocks exhibit a sudden shift at the p t boundary from latest permian values of 29 1 pdb to a minimum of 32 6 2 m above the p t boundary and then back to the permian value 4 m above the p t boundary after considering various factors we conclude that reduced surface water primary productivity following the p t mass extinction is largely responsible for the observed 13 c shift the abruptness of the 13 c shift in a sequence of continuous deposition argues that the strong pulse of extinction at the p t boundary was sudden rather than gradual marine primary productivity did not recover until at least 50 to 100 ka after the time of the p t boundary so a higher atmospheric p co 2 in the earliest triassic may have resulted from buildup of dissolved co 2 owing to reduced photosynthetic carbon demand in the surface water

large perturbations of the carbon cycle during recovery from the end permian extinction high resolution carbon isotope measurements of multiple stratigraphic sections in south china demonstrate that the pronounced carbon isotopic excursion at the permian triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the early triassic before ending abruptly early in the middle triassic the unusual behavior of the carbon cycle coincides with the delayed recovery from end permian extinction recorded by fossils suggesting a direct relationship between earth system function and biological rediversification in the aftermath of earth s most devastating mass extinction

multidisciplinary high resolution correlation of the permian triassic boundary abstract biostratigraphic correlation of the ten most important permian triassic boundary sections throughout tethys enables establishment of four conodont and ammonoid subdivisions within a stratigraphic interval one to a few metres thick representing less than 1 ma in ascending order they are conodonts clarkina changxingensis c deflecta zone hindeodus typicalis interval isarcicella parva zone and i isarcica zone and ammonoids pseudotirolites pleuronodoceras zone lower otoceras zone upper otoceras zone and ophiceras zone most of them can be traced to north america and the arctic region carbon isotope investigations of 24 sections along tethys and in greenland and spitzbergen confirm the consistency of 13c negative excursions at the permian triassic boundary together with an inconsistent ir anomaly eight sections show that in most cases there is a succession of ir anomaly denoting the end permian catastrophic environment 13c excursion biomass loss extinction p t boundary origination of newcomers potentially capable of intercontinental correlation within that short time interval there is an intercontinental sequence boundary at the top of the permian and a transgressive surface at the p t boundary followed shortly by a maximum flooding surface an intercontinental anoxia event accompanied the transgression three delineations of the mass extinction phases and three population explosions have been recognized and can be more or less correlated in south china and the southern alps radiometric dating of the volcanogenic boundary clays of meishan shangsi and the main stage siberian tunguss traps give an almost identical age of 250 ma thus implying a synchronous interregional volcanic event there are a few palaeomagnetic transforms within the ptb strata thus multidisciplinary research of the p t boundary strata allows subdivision of this short interval into more than ten intercontinentally correlatable parts each subdivision averages less than 100 ka in duration this may be the highest resolution obtained so far in pre cretaceous rocks high frequency milankovitch type cyclic deposits within the p t boundary beds enable correlation of even higher resolution in the lower yangtze area this high resolution is made possible because the p t transition is a time of saltation and catastrophy in geological history causality of the aggregation of events merits further investigation

response of sloping unconfined aquifer to stage changes in adjacent stream ii applications summary we convolve the system response functions of the linearised 1d equation of boussinesq extended for slope dupuit approximation derived in the companion paper of akylas and koussis akylas e koussis a d submitted for publication response of sloping unconfined aquifer to stage changes in adjacent stream i theoretical analysis and derivation of system response functions j hydrol and develop solutions for the interaction of a fully penetrating stream with a sloping unconfined aquifer taking also into account a low conductivity streambed layer these solutions give the aquifer stage and flow rate the flow exchange rate at the stream aquifer interface and the exchanged water volumes bank storage release the solutions are analytical when the flow inducing stream stage variations are common functions otherwise the convolution integral is evaluated numerically responses are compared for aquifers on positive negative and zero base slopes to a wave like change in the stage of the stream analytical and numerical convolution derived solutions are used to model the interaction of cedar river and its adjacent unconfined aquifer near cedar rapids iowa in the model the aquifer base is taken to be horizontal or inclined and the streambed clogged by a low conductivity sediment layer the model is verified against data not used in the calibration and is found to perform very well

palynofacies in a late silurian regressive sequence in the welsh borderland and wales the upper whitcliffe and lower part of the downton castle sandstone formations ludlow and pridoli series have been sampled from sequences distributed over an area roughly 4800 square km in west central england and wales ludfordian age rocks have been interpreted as the deposits of shelf and basin environments and those of the lower downton group as near shore to beach sections sampled from the shelf area are in the ludlow type area and in the usk may hill and woolhope inliers basin sediments were sampled at knighton the long mountain capel horeb and kington the samples were analysed for their palynological content and all the organic walled microfossils were studied together with the fragmentary remains of larger plants and animals using a series of ratios between different groups of microfossils it is apparent that there are consistent changes through time in both the palynomorph assemblages and in the structured and unstructured organic material dominance of some microplanktic groups taxa is used to define a new microphytoplanktic phase concept and to compare the sequence of palynoevents depositional environments inferred from palynofacies interpretation of the ludlow type area are closely comparable with those proposed previously from sedimentological data palynofacies sequences differ for the shelf and basin areas but show similar trends we have also recognized a dramatic shift in palynofacies at a level within the downton castle sandstone formation and its correlatives in both shelf and basin areas this change is tentatively interpreted as a storm event

a model for atmospheric co 2 over phanerozoic time a new model has been constructed for calculating the level of atmospheric co sub 2 over phanerozoic time which is much simpler mathematically than the blag model but more complex geologically and biologically results suggest that there has been a notable pattern of varying atmospheric co sub 2 level over the past 570 my with high levels during the mesozoic and early paleozoic and low levels during the permo carboniferous and late cenozoic sensitivity analysis shows that within reasonable limits of the principal governing parameters this qualitative trend of varying co sub 2 is relatively insensitive to the actual values chosen for these parameters causes of the co sub 2 variation are multiple and no single geological or biological process can be called upon to explain all co sub 2 variation for all time the calculated trend of co sub 2 over time agrees well with independent estimations of paleoclimates thus the greenhouse theory of paleoclimate on a long geological time scale is supported by the results of the present study

distribution of sedimentary organic matter in anisian carbonate series of s poland evidence of third order sea level fluctuations the stratigraphic distribution of sedimentary organic matter in anisian carbonate series of southern poland is studied with respect to relative sea level fluctuations palynofacies patterns clearly reflect transgressive regressive trends that are interpreted in terms of third order cyclicity major flooding phases are detected by maximum abundance of marine plankton in the upper bithynian and pelsonian transgressive and highstand deposits are recognized by changes in the terrestrial input of organic particles and the relative percentages and diversity of the plankton group the palynological data support the sequence stratigraphic interpretation based on sedimentological features and geochemical signatures the corresponding eustatic signals of sedimentary and organic facies are discussed the study highlights the potential of palynofacies analysis for sequence stratigraphical interpretation

bank storage characteristics of a finite aquifer due to sudden rise and fall of river level abstract unsteady seepage flow in a two dimensional water table aquifer is analysed for recession accretion due to a sudden rise or fall of water level in the adjoining river limiting solutions for long thin and short thick aquifers are deduced from the complete solution the long thin aquifer solution is similar to the usual one dimensional solution at small values of time the complete two dimensional solution is recommended for use because the one dimensional solution usually gives inaccurate results due to neglect of vertical motion implicit in the dupuit assumptions upon which the one dimensional solution is based

an unusual muddy epeiric carbonate reservoir the lower muschelkalk middle triassic of the netherlands the mud dominated lower muschelkalk carbonates middle triassic are a unique reservoir currently producing gas in the dutch de wijk field numerous gas shows scattered over the netherlands onshore and offshore suggest further currently unrecognized potential this study complements an extensive subsurface data set with selected outcrop information to localize missed opportunities and evaluates the factors controlling the development of this unusual reservoir type the muddy carbonates are deposits of a storm dominated epeiric carbonate ramp with negligible depositional gradient different marlstone dolomudstone and lime mudstone facies types reflect the low energy coastal plain to inner ramp and higher energy midramp to proximal outer ramp depositional environments the best reservoir facies is recognized in distal inner ramp algal dolomudstones porosity up to 24 and permeability up to 32 md because of the variable intensity of early facies related diagenesis the reservoir quality of dolomudstones decreases markedly in landward and seaward direction from the distal inner ramp the stacking of decimeter to meter thick reservoirs is reflected by a fourfold hierarchy of depositional cycles that can largely be recognized with conventional wire line logs high resolution outcrop and subsurface correlations reveal that stacks of thin bedded reservoir units most probably pinch out within a few kilometers and that their lateral continuity should not be overestimated despite the epeiric layer cake setting local reservoir occurrences are commonly situated above paleohighs of tectonic or halokinetic origin not only the reduced thickness of the lower muschelkalk above these paleohighs but also the presence and lateral extent of local reservoirs might be detected with seismic data the general facies and reservoir patterns exemplified by the lower muschelkalk may also be of use for reservoir prediction in similar epeiric settings elsewhere for instance in the middle east

characterization of properties and main processes related to the genesis and evolution of tropical mountain mires from serra do espinhaco meridional minas gerais brazil abstract the properties and components of the peat allow peatlands to function as water reservoirs which participate in the hydrological cycle by modulating water discharge in particular mountain peatlands from serra do espinhaco meridional minas gerais state brazil provide water of good quality for the nearby cities and also serve as habitats for wildlife and flora with unique endemic species in this paper we present the characterization of four mountain mires pau de fruta sao joao da chapada pinheiros and sempre viva based on morphological physical chemical and elemental properties analyzed in five selected peat cores pdf i pdf ii sjc pi and sv radiocarbon dating indicates that they started to form during the late pleistocene principal components analysis was applied to synthesize their main peat properties and underlying processes the first principal component pc1 is related to the relative content in inorganic versus organic matter of the peat most probably related to the evolution of the soils of the mires catchments i e soil erosion pc2 seems to be related to the incorporation of inorganic material by deposition of dust from regional sources pc3 reflects the content and preservation of plant remains and pc4 indicates the degree of peat decomposition our results suggest that mountain tropical mires from serra do espinhaco meridional are complex peatland ecosytems with a large potential for the reconstruction of environmental changes i e climate change occurred since the late pleistocene and that they should be fully protected

response of sloping unconfined aquifer to stage changes in adjacent stream i theoretical analysis and derivation of system response functions we study the interaction of a stream with a sloping unconfined aquifer that the stream is assumed to fully penetrate the analysis applies to flow in a vertical section considers the existence of a low conductivity streambed layer and the flow in the aquifer to be induced by variations of the stream stage invoking the dupuit assumption yields the 1 d boussinesq equation extended for a sloping base the boussinesq equation is linearised the derived flow model is critiqued and an objective procedure for determining the linearisation level is developed we solve the linear governing equation by the method of laplace transform with analytical inversion the horizontal aquifer case is treated in the zero slope limit the system response function is derived for the general case sloping aquifer sediment bed layer and for several specific cases and solutions are verified against known analytical results responses are contrasted for aquifers on positive negative and zero slopes to step changes in the stage of streams with and without a sediment bed layer the solutions give the aquifer stage and flow rate the flow exchange rate at the stream aquifer interface and the exchanged water volumes bank storage release

a unique geochemical record at the permian triassic boundary a 330 metre core drilled through the marine permian triassic boundary in the carnic alps of austria allows closely correlated studies of geochemistry petrography and palaeontology across the boundary the isotope shifts and metal concentrations are extended multiple and complex and do not resemble those seen at the cretaceous tertiary boundary both the carbon isotope shifts and the chemical events including an indium anomaly may have causes related to a major regression of the sea

end triassic calcification crisis and blooms of organic walled disaster species the triassic jurassic t j mass extinction event is marked by isotope anomalies in organic 13 corg and carbonate carbon 13 ccarb reservoirs these have been attributed to a rapid 4 fold rise in pco2 as a result of massive flood basalt volcanism and or methane hydrate dissociation here we examine the response of marine photosynthetic phytoplankton to the proposed perturbation in the carbon cycle our high resolution micropalaeontological analysis of t j boundary beds at st audrie s bay in somerset uk provides evidence for a bio calcification crisis that is characterized by 1 extinction and malformation in calcareous nannoplankton and 2 contemporaneous blooms of organic walled green algal disaster species which comprise in one case n70 of the total palynomorph fraction blooms of prasinophytes and acritarchs occur at the onset and in association with a prominent negative shift in 13 corg values close to the first appearance of the early jurassic ammonite psiloceras planorbis across the same interval we obtained palaeotemperature and palaeosalinity estimates from oyster low mg calcite based on mg ca sr ca and 18 o records the results of our palynological and geochemical analyses strongly suggest that shallow marine basins in nw europe during this period became salinity stratified inducing anoxic conditions the t j boundary event shows similarities with the permian triassic p t mass extinction event which was also marked by extensive flood basalt volcanism negative excursions in carbon isotope records a bio calcification crisis the development of shallow marine anoxia and mass abundances of acritarchs in the early triassic this leads us to suggest that the proliferation of green algal phytoplankton may be symptomatic of elevated carbon dioxide levels in the atmosphere and oceans during mass extinction events 2007 published by elsevier b v

parallel trends in organic and inorganic carbon isotopes across the permian triassic boundary stable carbon isotope ratios in both inorganic and organic reservoirs have been widely applied to model environmental and sedimentological changes on a global scale most studies dealing with major extinction events have used the record of inorganic carbon in this paper the authors report the relation between shifts in carbon 13 content of organic matter and coexisting carbonate fractions at a major extinction event the permian triassic boundary they found that both delta sup 13 c sub carb and delta sup 13 c sub org of the surface ocean varied dramatically across the boundary but the fractionation delta sup 13 c between organic matter and carbonate remained constant this result appreciably restricts the interpretation of changes in the carbon cycle during this critical interval the new data are best explained by a combination of two mechanisms for variation in delta sup 13 c sub carb 1 burial and erosion of organic carbon with a long time constant and 2 sequestration of organic carbon into shallow and deep oceanic reservoirs with a shorter time constant for application to their case the first mechanism is limited by possible buildup of marine pco sub 2 which would increase the isotopic fractionation factor the second mechanism is limited in application to short term transient variations in delta sup 13 c modelingmore of the carbon cycle and its variations of delta sup 13 c must take both mechanisms into account less

geochemical and organic carbon isotope studies across the continental permo triassic boundary of raniganj basin eastern india abstract organic carbon isotope and geochemical changes across a continental interior permo triassic boundary section from the raniganj basin india indicate a 9 drop in organic carbon 13c in the early triassic and synchroneity of this event throughout the pangea the study demands a common causative mechanism for the perturbation of the global carbon reservoir and not a combination of multiple causes a global sea level fall and oxidation of marine gas hydrates possibly increased the 12co2 input in the ocean atmosphere system which caused a climatic shift from humid to warm semi arid type and consequent extinction of land plants simultaneous increase in erosion from near barren lands change in the erosional base level and provenance deposited the boundary sandstone with positive europium anomaly and debris flow type matrix rich conglomerate no extraterrestrial source therefore is needed to explain this eu anomaly the response of the terrestrial plant community to this perturbation of the carbon reservoir was however sluggish and the 13c drop took place slowly being maximal in the early triassic only

stable carbon isotope signature in mid panthalassa shallow water carbonates across the permo triassic boundary evidence for 13 c depleted superocean the jurassic accretionary complex in southwest japan contains exotic blocks of the permo triassic limestone primarily deposited on ancient mid oceanic seamounts in an ancient pacific ocean or superocean panthalassa this study examines stable carbon isotope compositions 13ccarb and 13corg of such open ocean shallow water limestone across the permo triassic boundary ptb at kamura and taho in southwest japan the results show an almost identical secular change in 13ccarb values with a remarkable negative spike across the ptb in both sections this confirms for the first time that the mid panthalassa shallow water carbonates are bio and chemo stratigraphically correlated not with previously studied ptb sections from the peripheries of pangea the negative shift in 13ccarb occurs parallel to that of 13corg in both sections and the difference 13c 13ccarb 13corg remains nearly constant throughout the sections this implies that the 13c depleted water should have developed widely probably in a global extent throughout the superocean panthalassa across the ptb these findings suggest that a large input of 12c enriched carbon into the ocean atmosphere system has occurred and may have caused a global environment change probably relating to the greatest mass extinction in the phanerozoic

stable carbon isotope stratigraphy across the permian triassic boundary in shallow marine carbonate platforms nanpanjiang basin south china a distinct negative 13c excursion is documented in two permian triassic sections heping and taiping in shallow marine carbonate platform deposits in the nanpanjiang basin south china these sections span from the changhsingian to the dienerian and are characterized by a distinct marine boundary facies change from massive skeletal lime packstone in the changhsingian to distinctive calcimicrobial framestone in the griesbachian hindeodus parvus zone the 13corg and 13ccarb excursions occur directly after the onset of the calcimicrobial framestone herein termed the permian triassic boundary event and before the first occurrence of h parvus the isotope shifts are associated with a sharp drop in species abundance and diversity and coincide with a decrease in total organic carbon toc content the shift towards depleted values in 13corg and 13ccarb at the permian triassic boundary event together with low toc contents persists throughout the griesbachian h parvus zone these data document a corresponding negative shift of 13corg and 13ccarb values and low toc contents with the onset of growth of calcified microbial framestones a postextinction disaster facies immediately below the base of the griesbachian h parvus zone based on paleontological evidence the first occurrence of the disaster facies follows the extinction event which implies that the 13c depleted values above this facies postdate the event this suggests that two separate events had to account for the initiation of the extinction and the 13c excursion however the consequences that led to the negative isotopic shift might be linked to the intriguing recovery lag of early triassic ecosystems based on data from ptb sections worldwide of a greater 13c offset in high compared with low latitudes we propose that methane eruptions from thermal destabilization of high latitude clathrate deposits may have led to the negative 13c shift and may have caused long term adverse ecological conditions

carbon isotope stratigraphy and palynostratigraphy of the triassic jurassic transition in the tiefengraben section northern calcareous alps austria abstract the end triassic is characterized by enhanced rates of biotic turnover in both the marine and terrestrial realms carbon isotope anomalies have been reported worldwide that may indicate coeval global disturbances in the biogeochemical cycles here we present the results of an integrated study of the palynomorph assemblages and the carbon isotope composition of organic matter in the tiefengraben section near st wolfgang austria carbon isotope values from bulk organic matter show significant fluctuations through the triassic jurassic t j boundary interval with two prominent negative 13 c org excursions an initial negative carbon isotope excursion occurs at the base of the kendlbach formation tiefengraben member pre planorbis beds although triassic ammonoids and conodonts have their highest occurrence at the top of the underlying kossen formation the palynomorph and calcareous microfossil assemblages indicate still a rhaetian age for the lower part of the tiefengraben member high abundance of prasinophytes during the interval of the initial carbon isotope excursion may represent a bloom of green algae that flourished as a result of the disturbance of the marine ecosystems increased spore abundance together with the disappearance of distinctive late triassic pollen types e g ovalipollis rhaetipollis indicate vegetation changes on land that are contemporaneous with the marine biotic crisis a second negative carbon isotope excursion occurs in the middle part of the tiefengraben member based on palynological evidence the t j boundary may be drawn at about this level by the lowest occurrence of cerebropollenites thiergartii the established carbon isotope curve as well as palynostratigraphic and other biostratigraphic events can be correlated with st audrie s bay england

carbon isotope excursions and microfacies changes in marine permian triassic boundary sections in hungary abstract several permian triassic boundary sections occur in various structural units within hungary these sections represent different facies zones of the western palaeotethys margin the gardony core in the ne part of the transdanubian range typically represents the inner ramp while the balvany section in the bukk mountains of northern hungary represents an outer ramp setting the two sections have different patterns for their 13 c values the balvany section shows a continuous change towards more negative 13 c values starting at the first biotic decline followed by a sharp quasi symmetric negative peak at the second decline the appearance of the 13 c peak has no relationship to the lithology and occurs within a shale with low overall carbonate content indicating that the peak is not related to diagenesis or other secondary influences instead the shift and the peak reflect primary processes related to changes in environmental conditions the continuous shift in 13 c values is most probably related to a decrease in bioproductivity whereas the sharp peak can be attributed to an addition of c strongly depleted in 13 c to the ocean atmosphere system the most plausible model is a massive release of methane hydrate the quasi symmetric pattern suggests a rapid warming cooling cycle or physical unroofing of sediments through slope failure and releasing methane hydrate the gardony 1 core shows a continuous negative 13 c shift starting below the p t boundary however the detailed analyses revealed a sharp 13 c peak in the boundary interval just below the major biotic decline although its magnitude doesn t reach that observed in the balvany section based on careful textural examination and high resolution stable isotope microanalyses we suggest that the suppression of the 13 c peak that is common in the oolitic boundary sections is due to combined effects of condensed sedimentation sediment reworking and erosion as well as perhaps diagenesis

paleodust deposition and peat accumulation rates bog size matters abstract we present a high resolution peat paleodust and accumulation rate record spanning the last 8300 years from draftinge mosse 400 ha southern sweden 57 06 27 6 n 13 42 54 1 e the record was analysed for peat accumulation rates par elemental concentrations mineralogy and plant macrofossil content five periods of increased mineral deposition were recorded the first event occurred between 6280 and 5570 cal bp during the fen to bog transition this is followed by four atmospheric mineral dust events de which were recorded in the ombrotrophic section of the sequence at cal bp 2200 1385 1150 830 590 and from 420 to the present statistical analysis and elemental ratios indicated that both the mineralogy and grain size shifted when the system transitioned from fen into bog showing that the governing transport process shifted with the peatland succession stages this highlights the importance of identifying peatland succession stages within peat paleodust studies following all four de increases in par were observed implying a coupling to dust deposition comparison of de and par with a paleodust record from store mosse a 20 times larger bog located ca 18 km away kylander et al 2016 showed that both par and dust deposition are largely represented by single core reconstructions indicating that they are driven by a common climate forcing mechanism however higher par and dust deposition rates were observed in the more moderately sized draftinge mosse suggesting that the size of the bog is important to consider in peat paleodust studies furthermore the smaller bog responded more rapidly to hydrological changes indicating that the size of the bog affects its buffering capacity authigenic carbonates observed here during episodes of rapid peat growth coincide with changes in ree ratios indicating that authigenic peat processes potentially cause ree fractionation

time series analyses for karst river interactions assessment case of the coulazou river southern france summary in many karst systems throughout the world numerous karst features facilitate the exchange of water between the surface the vadose zone and the saturated zone of the aquifer these interactions play actually a prominent role in the ground and surface waters circulation this study aims at assessing karst river interactions by the way of flood hydrograph analysis and new tools for time series analysis in this field of research as in many others binary karst system the captured waters of the coulazou river travel through conduits and preferential flow paths in the vadose zone and join the saturated zone of the aquifer this river is an ephemeral river in a mediterranean context where rapid and intense floods occur each year this hydrologic behaviour is appropriate to study the transfer of a flood through a karst area the water level in caves the rainfall all over the karst aquifer catchment area the piezometric level within the karst aquifer and the discharge in the river upstream and downstream of the karst aquifer are measured in order to understand the karst river exchanges during a flood the modification of the surface flows in the river is treated as a linear time invariant system lti system correlation and spectral analyses are used to understand how the lti system dissipates or enhances the flood wave energy for several floods the frequency response function estimations are interpreted in term of flood wave modification through the karst area in this way according to the initial state of the karst river system the autogenic and or allogenic recharge of the aquifer may induce surge flows and a significant karst contribution to surface flows