calibrating the end permian mass extinction the end permian mass extinction was the most severe biodiversity crisis in earth history to better constrain the timing and ultimately the causes of this event we collected a suite of geochronologic isotopic and biostratigraphic data on several well preserved sedimentary sections in south china high precision u pb dating reveals that the extinction peak occurred just before 252 28 0 08 million years ago after a decline of 2 per mil in 13c over 90 000 years and coincided with a 13c excursion of 5 that is estimated to have lasted 20 000 years the extinction interval was less than 200 000 years and synchronous in marine and terrestrial realms associated charcoal rich and soot bearing layers indicate widespread wildfires on land a massive release of thermogenic carbon dioxide and or methane may have caused the catastrophic extinction

facies architecture and depositional dynamics of the upper permian rangal coal measures bowen basin australia the upper permian rangal coal measures in the northern bowen basin australia accumulated during rapid basinal aggradation in a retroarc foreland basin setting they reflect peatland deposition towards the close of a long lived climatic regime that came to an abrupt termination at the permian triassic boundary which is well developed in the newlands mine highwall and adjoining borefield six lithofacies are represented in the newlands district 1 erosionally based vertically stacked ribbon and sheet like sandstone bodies up to 30 m thick and 1000 m wide 2 heterolithic lobes and wedges 3 interbedded siltstone and sandstone sheets 4 interlaminated claystone and coal stringers 5 laterally extensive bituminous coal sheets and 6 laterally extensive laminated carbonaceous siltstone sheets this facies assemblage is interpreted to correspond to six alluvial cold climate depositional environments 1 trunk river channels and crevasse feeder channels 2 levee bank proximal crevasse splay 3 distal splay overbank 4 marsh 5 peat mire and 6 floodbasin lake respectively the sequence architecture at newlands reveals that a prolonged period of peat deposition was progressively terminated by northward stepping lobes of fluvial sediment in the south and by lacustrine drowning in the north exceptionally well developed composite elongate crevasse splay microdeltas up to 26 m thick and 3000 m long indicate that crevassing was responsible for the localized emplacement of thick sediment packages on the proximal floodplain in the absence of active siliciclastic sedimentation peat mire environments expanded from the distal floodplain extending across abandoned depositional lobes the geometry of these deposits reflects in large part accommodation space developed by the compaction of the peat precursor of the thick and laterally extensive upper newlands seam sequential compaction of peat by clastic overburden controlled the nucleation and location of succeeding clastic packages the behavior of the peat under compactional load largely controlled the lateral facies mosaic and stacking pattern of depositional units on a district scale

permian and triassic greenhouse crises paleoclimatic time series from permian and triassic paleosols reveal transient episodes of unusually warm and wet conditions interrupting long periods of cool and dry conditions usual for calcareous red paleosols some of these paleoclimatic events are known from stomatal index of fossil lepidopteris leaves to have been episodes of elevated global atmospheric co2 the magnitude of 19 known permian and triassic greenhouse crises varied considerably and they offer new evidence for the relationship between paleoclimate and atmospheric co2 levels these greenhouse crises also had marked effects on global lowland vegetation introducing frost sensitive tropical lycopsids to high latitudes and drought tolerant conifers to low latitude lowlands greenhouse events punctuate phases in plant evolution ottokaria callipteris plumsteadia rufloria lidgettonia tatarina pleuromeia and dicroidium scytophyllum floras greenhouse events also punctuate the evolution of reptilian dynasties successive pelycosaur dinocephalian dicynodont rhynchosaur and dinosaur faunas and respiratory adaptations such as enlarged bony secondary palate greenhouse crises of the late and middle permian were the most severe known and suggest a role for atmospheric pollution with ch4 and co2 in those mass extinction events probably from thermogenic cracking of coals by intrusive feeder dikes of flood basalts because of formalities in boundary definition these mass extinctions are neither end permian nor end guadalupian but upper changhsingian and mid capitanian respectively

the pangaea megamonsoon records evidence from the triassic mungaroo formation northwest shelf of australia abstract an integrated analysis in this study of paleogeographic paleontologic seismic and sedimentologic data has been used to explain the effect of the pangaean megamonsoon on the whole triassic especially the middle late triassic mungaroo formation in the north carnarvon basin northwest shelf of australia our results show that the three triassic formations from bottom to top locker shale mungaroo formation and brigadier formation comprise a complete depositional cycle and correspond to an undeveloped strong and weak monsoon periods respectively during the strong monsoon period of the mungaroo formation the palynological evidences exhibited mixture spore pollen characteristics of the hygrophytic assemblage spore pollen from the pteridophyte spores seed ferns and cycads pollen in humid environment of lowlands and coastal plain and the xerophytic assemblage pollen from the drought tolerant plants of the interior mountainous areas the sedimentary evidences of the mungaroo formation show low angle shingled progradational seismic reflection configuration the highly seasonal variations in precipitation during deposition of the mungaroo formation exhibited typical sandwiched depositional characteristics of coarse channels sandstone fining upward fluvial aggradational cycles facs with poor to moderately sorting and angular to subangular roundness organic mudstone and coal seam interbedded finally in contrast to today s typical examples of poyang lake delta a shallow water braided delta conceptual depositional model of the mungaroo formation is formed with a large proximal and distal delta plain and small delta front the model results serve mainly to indicate the importance of various climate forming factors climate topography eustatic whereas tectonic activity unlikely played any significant role in this process

the terrestrial permian triassic boundary event bed is a nonevent comment we welcome the fact that gastaldo et al 2009 1 have been continuing research in the karoo of south africa those of us who have worked there know how important new research in this area is if we are to ever understand the causes of the permian triassic mass extinction on land however here

multiple early triassic greenhouse crises impeded recovery from late permian mass extinction the late permian mass extinction was not only the most catastrophic known loss of biodiversity but was followed by unusually prolonged recovery through the early triassic opinion has been divided on whether delayed recovery was a legacy of especially profound ecological disruption or due to additional environmental perturbations new records from the sydney basin in southeastern australia now reveal five successive late permian and early triassic spikes of unusually high atmospheric co2 and profound chemical weathering these successive atmospheric co2 greenhouse crises coincided with unusually warm and wet paleoclimates for a paleolatitude of 61 s successive transient greenhouse crises punctuated long term cool dry and low co2 conditions and may account for the persistence of low diversity and small size in early triassic plants and animals

glossopteris flora in the permian weller formation of allan hills south victoria land antarctica implications for paleogeography paleoclimatology and biostratigraphic correlation abstract the permo triassic victoria group in south victoria land antarctica is a heterogeneous sequence of glacial tillite beds carbonaceous and non carbonaceous fluvial deposits and volcaniclastic strata the carbonaceous beds are rich in plant fossils associated with coal seams in antarctica the geological record of the late paleozoic ice age is restricted to the early permian after deglaciation the glossopteris flora thrived in polar forests in antarctica throughout the permian but disappeared at the end permian extinction here we describe the first comprehensive record of the glossopteris flora from the permian weller formation of allan hills south victoria land antarctica the flora is well preserved and comprises pteridophytes and gymnosperms the pteridophytes include the sphenopsid order equisetales and the gymnosperms comprise glossopteridales equisetales are represented by branched and unbranched axes whereas glossopteridales are highly diverse encompassing gangamopteris glossopteris surangephyllum sterile scale leaves namely scirroma sp nautiyalolepis sp utkaliolepis indica scale leaf a and scale leaf of male fructification eretmonia the flora of the weller formation shows close similarity with the late permian assemblages of india south africa and australia gangamopteris an index fossil of the early permian formations of different gondwana continents had extended stratigraphic range in the late permian weller formation of allan hills antarctica played a crucial role in the dispersal of glossopteris flora because of its central position in gondwana

earliest triassic claystone breccias and soil erosion crisis abstract chemostratigraphic methods 13corg for pinpointing the permian triassic boundary in nonmarine rocks of antarctica australia and south africa have drawn attention to unusual claystone breccias at this horizon of the greatest extinction in the history of life on earth these rocks differ from other breccias in having a high proportion of clasts with birefringence microfabrics sepic plasmic fabrics characteristic of soils and can be called sepic pedoliths in the terminology of soil science at many localities earliest triassic sepic pedoliths are thin 5 15 cm beds but some fill shallow paleochannels and pinch out laterally other non marine breccias at the permian triassic boundary are dominated by fragments of coal pedogenic carbonate nodules and deeply weathered volcanic rock fragments earliest triassic sepic pedoliths record an unusually severe and widespread episode of soil erosion associated with forest dieback at the permian triassic boundary comparable sepic pedoliths are found in debris flows after clear cutting of forests in western oregon today studies of these modern deposits show that sepic soil peds do not withstand weathering for more than a few months such clayey clasts are held together mainly by roots and fungi which decay rapidly in soils and streams these modern analogs demonstrate that terminal permian soil erosion was rapid and profound sepic pedoliths are also known at other times of mass extinction such as the triassic jurassic boundary but are not yet known before the devonian advent of trees and forested clayey soils

long term cycles of triassic climate change a new δ18o record from conodont apatite jat and isw gratefully acknowledge financial support from the australian research council dp1096252 mr is grateful for financial support from progetto d ateneo 2009 cpda090175 09 and 2012 cpda 121100 and prin 2008 2008bef5z7 005

multiple climatic changes around the permian triassic boundary event revealed by an expanded palynological record from mid norway here we present the palynological record from two shallow core holes 6611 09 u 01 and 02 from the trondelag platform offshore mid norway consisting of 750 m of upper permian and lower triassic sediments the relatively homogeneous assemblages recovered from the upper permian deposits are dominated by gymnosperm pollen mainly pteridosperms at the base of the griesbachian numerous spore species appear in the record leading to an increased diversity the change at this boundary is also marked by the massive reduction of one group of pteridosperm pollen vittatina together with other typical permian elements e g lueckisporites virkkiae this group is rare but consistently present in the lower part of the griesbachian and it gradually disappears in its upper part the distribution of other groups such as taeniate and non taeniate bisaccate gymnosperm pollen pteridosperms and conifers shows no significant change across the boundary whereas spores and other gymnosperm pollen increase in diversity and abundance these changes coincide with the formational change between the schuchert dal formation upper permian and the wordie creek formation griesbachian equivalents late permian and griesbachian palynomorph assemblages display different patterns the former show a homogeneous composition of low diversity whereas the latter reflect diverse and variably composed floras the data suggest that the arid phase of the late permian was followed by a humid phase at the base of the griesbachian in the griesbachian section a succession of six distinct palynological assemblages phase ii vii can be inferred comparable changes have been described from east greenland the variations in the palynological record are interpreted to reflect changing ecological conditions e g changing humidity comparable variations in the distribution of 13 c isotope values reported from various sections from greenland and china showing stable values during the late permian and highly variable values during the griesbachian suggest common causes for the observed fluctuations multiphase volcanic activity of the siberian traps seems to be the most likely candidate to have caused the variations in the 13 c isotope as well as in the palynological record in contrast to the common claim that marine and terrestrial biota both suffered a mass extinction related to the permian triassic boundary event the studied material from the norwegian midlatitudinal sites shows no evidence for destruction of plant ecosystems the presence of diverse microfloras of griesbachian age supports the idea that the climate in this area allowed most plants to survive the permian triassic boundary event

global coal gap between permian triassic extinction and middle triassic recovery of peat forming plants early triassic coals are unknown and middle triassic coals are rare and thin the early triassic coal gap began with extinction of peat forming plants at the end of the permian ca 250 ma with no coal known anywhere until middle triassic 243 ma permian levels of plant diversity and peat thickness were not recovered until late triassic 230 ma tectonic and climatic explanations for the coal gap fail because deposits of fluctuating sea levels and sedimentary facies and paleosols commonly found in coal bearing sequences are present also in early triassic rocks nor do we favor explanations involving evolutionary advances in the effectiveness of fungal decomposers insects or tetrapod herbivores which became cosmopolitan and much reduced in diversity across the permian triassic boundary instead we favor explanations involving extinction of peat forming plants at the permian triassic boundary followed by a hiatus of some 10 m y until newly evolved peat forming plants developed tolerance to the acidic dysaerobic conditions of wetlands this view is compatible not only with the paleobotanical record of extinction of swamp plants but also with indications of a terminal permian productivity crash from delta sup 13 c sub org and total organic carbon of both nonmarine and shallow marine shales 205 refs 3 figs more 3 tabs less

low oxygen levels in earliest triassic soils an earliest triassic methane postapocalyptic greenhouse following the permian triassic p t extinction event was proposed on the basis of evidence of deeply weathered paleosols at high latitudes with features of low latitude soils and low stomatal index values of seed fern leaves reexamination of distinctive phyllosilicates unique to a single stratigraphic level in paleosols located just above the isotopically defined permian triassic boundary in australia and antarctica furnishes additional tests of this hypothesis illite is the dominant clay mineral in earliest triassic paleosols from antarctica but the paleosols also contain conspicuous green nodules of coarsely crystalline berthierine examples from the geologic record and from experimental studies indicate that the formation of berthierine is restricted to reducing conditions the occurrence of this unusual mineral in soils may indicate soil oxygen consumption by the influx of atmospheric methane to form carbon dioxide which in turn warmed the earliest triassic giving rise to a postapocalyptic greenhouse

abrupt chemical weathering increase across the permian triassic boundary previous studies have suggested a variety of causes for the end permian extinction event including a bolide impact flood basalt volcanism methane clathrate dissociation or some combination of catastrophic processes one common feature of these hypotheses is the prediction of an enhanced earliest triassic greenhouse new high resolution geochemical results from graphite peak antarctica support an abrupt increase in chemical weathering in the earliest triassic among otherwise genetically similar paleosols of similar provenance relative to the latest permian paleosols the earliest triassic paleosol exhibits greater leaching greater accumulation of immobile rees and evidence of lower soil po2 with no evidence of an erosional unconformity between the paleosols which are separated by 15 cm stratigraphically these results support a rapid shift perhaps 10 000 years to an earliest triassic greenhouse and a role for methane release in the extinction event and its aftermath

carbon isotope compositions of the late permian carbonate rocks in southern china their variations between the wujiaping and changxing formations abstract the carbon isotope compositions of the upper permian marine carbonate rocks in southern and eastern guizhou and central guangxi of southern china have been investigated the results reveal a 13c anomaly at the boundary between the wujiaping and changxing formations of the upper permian the 13c values in limestones of the wujiaping formation are mostly within the range of 3 5 and 5 0 whereas the 13c values in limestones of the changxing formation are mostly less than 3 0 ranging from 0 2 to 3 1 the carbon isotope negative excursion at the boundary between these two formations is helpful to differentiate the two stages wuchiapian and changxingian of the late permian in southern china if substantiated by sufficient fossil materials this also means that the 13c values of the carbonates were decreasing throughout the late permian and this change was accompanied by some rapid falls such as those in the permian triassic boundary and possibly in the wujiapingian and changxingian boundary during the late permian the consumption of organic carbon by the oxidation of the previously formed coals as a result of dry climates and tectonic uplifting must have exceeded the burial of organic carbon as in coal in addition lack of coal deposits during the late tatarian on the gondwana fragments suggests a global reduced coal accumulation consequently more 12c rich co2 was released into the atmosphere which might contribute to the 13c depletion seen in upper permian marine carbonates

late permian flora and vegetation changes near the permian triassic boundary in the landete section of the alcotas formation se iberian ranges spain on the basis of rich and diverse thuringian palynomorph samples gathered from successive levels of the landete section alcotas formation se iberian ranges the succession of palynofloras and the vegetation dynamics have been studied in detail with the aid of quantitative analysis the aim of this study is to elucidate the timing and scenario of the biotic crisis during the latest permian before the actual permian triassic boundary and to determine the shape of the extinction at the local level four successive associations have been recognized through time the oldest a klausipollenites lueckisporites association this was followed by a klausipollenites falcisporites an alisporites lueckisporites and finally a re establishment of a klausipollenites lueckisporites association it is worth noting the scarcity or lack of fungal remains which indicates that in this area the fungal spike event cannot be demonstrated the palynomorph associations are dominated by non striate bisaccate pollen and verrucate spores in contrast with other palynofloras from western europe north america and continental series in eurasia the study indicated the absence of transitional floras and a dieback of diversity that ranges from 35 to 67 depending on the group population density of the 27 taxa identified underwent a significant decline ca 75 average indicating that at least at a local level the biotic crisis occurred prior to the p t boundary futhermore the quantitative analysis of the successive palynomorph assemblages allowed us to locally recognize the evolution of vegetation in which competitive exclusion and competitive release events took place

the record of triassic charcoal and other evidence for palaeo wildfires signal for atmospheric oxygen levels taphonomic biases or lack of fuel abstract as wildfires are today important sources of disturbance in many terrestrial ecosystems it is of great interest to understand how different environmental parameters and fire activity interacted during past periods of the earth history fossil charcoal inertinites and pyrogenic polycyclic aromatic hydrocarbons pahs represent the only direct evidence for the occurrence of such palaeo wildfires in the present study a review of published data together with new data on the occurrence of fossil charcoal for the permian and the triassic is presented for a long time it has been speculated that an assumed lack of evidence for palaeo wildfires during the triassic should be explained by a large drop in atmospheric oxygen concentration following or during the end permian mass extinction event preventing the occurrence of wildfires however evidence for palaeo wildfires is relatively common in many middle and late triassic strata whereas such evidence is almost totally lacking from early triassic sediments the interpretation of this charcoal gap or depression is difficult as many factors e g atmospheric oxygen concentration taphonomical biases lack of sediments suitable for the preservation of macroscopic charcoal lack of fuel and ignorance of scientists may have influenced not only the production but also the preservation and recovery of evidence for palaeo wildfires during this period thus it is not clear whether this early triassic charcoal gap can also be seen as evidence for an assumed wildfire gap or not without any doubt further investigations on the early triassic record of charcoal and other evidence for palaeo wildfires will be necessary before this problem can be solved in fact it can be expected that the number of published records of early triassic evidence for palaeo wildfires will increase in the future as more and more scientist working on sediments of this age may become aware of the interest in fires from this time this will certainly make it possible to give a much better picture of the temporal and regional distribution of wildfires during this period in the future

constraints on carbon accumulation rate and net primary production in the lopingian late permian tropical peatland in sw china article i nfo during the permian peatland as represented in extensive coal deposits was a major component of the global carbon cycle carbon storage in peatland is a balance between decay and net primary production npp which in turn are sensitive to variations in the concentration of atmospheric co2 and o2 to evaluate peatland carbon storage and npp during the lopingian a period thought to be characterised by higher atmospheric o2 and co2 than modern levels spectral analyses of geophysical data from a 15 1 m thick lopingian upper permian coal in southwestern china were conducted to define the time frame of temporal carbon accumulation in tropical peatland the result shows that the mineral matter content ash yield of the coal was possibly influenced by 123 ka eccentricity 35 6 ka obliquity and 21 2 ka precession milankovitch periodicities using this timeframe and an understanding of carbon loss during coalification the lopingian tropical peatland carbon accumulation rate is calculated to be 61 1 73 0 g c m 2 yr which is expected to correspond to a npp of 611 1460 g c m 2 yr respectively a comparison between the predicted pennsylvanian late carboniferous npp and modern values indicates that the permian npp calculated is consistent with geochemical and paleobotanical models supporting a proposal that productivity was mainly controlled by temporal atmospheric o2 and co2 levels

the unusual sedimentary rock record of the early triassic a case study from the southwestern united states abstract sedimentary systems as well as the earth s biota changed dramatically following the end permian mass extinction this global sedimentological transformation is reflected in the widespread occurrence of flat pebble conglomerates subtidal wrinkle structures microbialites and carbonate seafloor fans in various lower triassic sections as a case study a facies analysis of the lower triassic virgin limestone member of the moenkopi formation and the middle and upper members of the union wash formation southwestern united states was conducted and all unusual facies were documented within a palaeoenvironmental framework the occurrence of the flat pebble conglomerates and wrinkle structures is significant because these reflect a long term reduction in vertical bioturbation in the case of the subtidal microbialites and carbonate seafloor fans their formation is linked to an increase in alkalinity the presence of these facies in the uppermost lower triassic strata of the southwestern united states indicates that reduced levels of infaunal bioturbation as well as and perhaps a consequence of unusual ocean chemistry extended for 5 6 million years after the end permian mass extinction suggesting that depositional environments as well as the biota were significantly affected by the extinction event

triassic climates state of the art and perspectives abstract the climate of the triassic period was characterized by a non zonal pattern dictated by a strong global monsoon system with effects that are most evident in the tethys realm this strong monsoonal regime is related to the aggregation of the pangaean supercontinent which by triassic time was already completed climate oscillations existed within this framework the harsh hot house climatic conditions that characterized the late permian and perhaps precipitated the end permian mass extinction were probably maintained during the early triassic and may account for the impoverished but distinctive faunal and floral lower triassic associations although metazoan reef builders were probably the most affected group carbonate production remained high at least in the western tethys realm the middle triassic was characterized locally by humid episodes although their geographical distribution has yet to be clarified the carnian pluvial event marks an episode of increased rainfall documented worldwide was the most distinctive climate change within the triassic different hypotheses have been proposed for its causes changes of atmospheric or ocean circulation driven by plate tectonics a peak of the global monsoon due to maximum continent aggregation or triggering by the eruption of a large igneous province subsequently the late carnian and norian seem to have been climatically stable although minor climatic changes have recently been described even from this time period finally the end triassic extinction event is also associated with climate change specifically warming and increased rainfall but this evidence comes mostly from the northern parts of the central atlantic magmatic province and the global pattern of climate change at the triassic jurassic boundary has still to be resolved many facets of triassic climate are intriguing and deserve further research however palaeoclimate studies on the triassic have so far been carried out only locally with different proxies those proxies will require inter calibration in order to depict correctly the temporal and geographical patterns of triassic climate

stable carbon and oxygen isotope shifts in permian seas of west spitsbergen global change or diagenetic artifact we performed petrographic cathodoluminescence electron microprobe and isotopic analyses of brachiopod shells from the permian kapp starostin formation in west spitsbergen to reevaluate the 9 negative shift in 13c and 18o values reported in 1989 by m gruszczynski s halas a hoffman and k malkowski the 13c and 18o values within shells typically decrease with increasing luminescence indicating diagenesis nonluminescent nl shell 13c and 18o values are 4 3 and 6 2 higher respectively than those of associated cements and matrix for the same stratigraphic interval 13c and 18o values of the nl shells are equal to or substantially greater than those reported by gruszczynski et al for the interval where those authors saw a 10 13c shift our mostly nl spiriferella polaris shells only yield a 1 5 shift gruszczynski et al reported a 9 18o shift whereas we observe almost none our results strongly suggest that the 9 isotopic shifts reported in gruszczynski et al are diagenetic artifacts on the other hand their kazanian tatarian 13c maximum of 7 5 is substantiated by our data this late permian 13c maximum represents the highest spiriferid brachiopod 13c values in the phanerozoic and within stratigraphic uncertainty correlates with the whole rock 13c maximum in east greenland and northwestern europe the 13c shift may reflect changes in global storage of organic carbon indicated by coal volume changes in the late permian

sequencing events across the permian triassic boundary guryul ravine kashmir india abstract the permian triassic boundary ptb section at guryul ravine kashmir india comprises a 100 m thick apparently conformable succession of mixed siliciclastic carbonate sediments deposited in a deep shelf or ramp setting this section although long important in debates concerning placement of the ptb has not previously been the focus of an integrated chemostratigraphic study in the present study samples from a 20 m thick interval straddling the ptb were analyzed for major and trace element concentrations toc tic rees and organic 13c 15n to investigate contemporaneous environmental changes the guryul ravine section exhibits a sequence of discrete events that provide potentially important information about the character and cause s of the ptb two transient negative c isotopic excursions within the upper changxingensis zone predate the late permian event horizon lpeh i e the global mass extinction event by 200 400 kyr and are associated with the onset of a major eustatic rise and with secondary extinction peaks these excursions may record minor environmental disturbances prior to the main end permian crisis supporting an intrinsic mechanism such as volcanism and climate change rather than an extrinsic mechanism such as a bolide impact the onset of a large 4 0 to 4 5 sustained negative c isotope shift marks the lpeh which is located at the zewan khunamuh formation contact 260 cm below the biostratigraphically defined ptb the guryul ravine section exhibits a stepwise extinction pattern with the largest peak between the lpeh and ptb and a secondary peak just above the ptb a pattern similar to that observed in the meishan d gssp

impacts of global warming on permo triassic terrestrial ecosystems geologists and palaeontologists have expressed mixed views about the effects of the end permian mass extinction on continental habitats and on terrestrial life current work suggests that the effects on land were substantial with massive erosion following the stripping of vegetation associated with long term aridification and short term bursts of warming and acid rain wildfires at the permo triassic boundary contributed to the removal of forests and the prolonged absence of forests from the earth s surface for up to 10 myr these physical crises on land impinged on the oceans suggesting tight interlocking of terrestrial and marine crises levels of extinction on land may well have been as high as in the sea and this is certainly the case for tetrapods the mass extinction seems to have been less profound for plants and insects but it is hard at present to disentangle issues of data quality from reductions in abundance and diversity several killing agents have been proposed and of these tetrapods may have succumbed primarily to acid rain mass wasting and aridification plants may have been more affected by the sudden effects of heating and wildfires and the crisis for insects has yet to be explored

global cooling by grassland soils of the geological past and near future major innovations in the evolution of vegetation such as the devonian origin of forests created new weathering regimes and soils alfisols histosols that increased carbon consumption and sequestration and ushered in the permian carboniferous ice age similarly global expansion of grasslands and their newly evolved carbon rich soils mollisols over the past 40 million years may have induced global cooling and ushered in pleistocene glaciation grassland evolution has been considered a consequence of mountain uplift and tectonic reorganization of ocean currents but it can also be viewed as a biological force for global change through coevolution of grasses and grazers organisms in such coevolutionary trajectories adapt to each other rather than to their environment and so can be forces for global change some past farming practices have aided greenhouse gas release however modern grassland agroecosystems are a potential carbon sink already under intensive human management and carbon farming techniques may be useful in curbing anthropogenic global warming

time specific aspects of facies state of the art examples and possible causes abstract the term time specific facies tsf was introduced to the scientific community by the late otto h walliser to refer to unique facies typical of particular narrow intervals some of which were related to bioevents in some senses however the concept was recognized much earlier and is even engrained in the very names of some geologic periods the concept of time specific facies is expanded slightly herein to include distinctive or unique regional to global characteristics of the sedimentary record that characterize particular intervals of geologic time the recognition of time specific and widespread processes in the sedimentary record is a critical step in unraveling the interplay between processes of differing scale these range from very short term but widespread facies that overlap with event deposits to general facies types that may persist for intervals up to 10s of millions of years in duration this paper briefly summarizes the history of development of the tsf concept provides examples to illustrate a few of the key aspects of time specific facies and offers a few tentative explanations for this phenomenon among the factors that control tsfs abrupt changes in redox conditions and early diagenetic mineralization sedimentary condensation often associated with abrupt sea level change altered climate and paleoceanography and biotic evolution and extinction seem to be most critical and permit a preliminary genetic classification of tsfs inevitably however many tsfs reflect multiple effects and some remain largely unexplained

deposition in the kuznetsk basin siberia insights into the permian triassic transition and the mesozoic evolution of central asia abstract this paper describes the permian mesozoic stratigraphy of the kuznetsk basin southern siberia which is adjacent to the vast and hydrocarbon rich west siberian basin and on the edge of the siberian flood basalts the basin fill is permian to cretaceous in age and is dominated by non marine siliciclastics up to 7 km thick palaeocurrent indicators show dominant flow to the north northeast during the permian to jurassic fourteen lithofacies are grouped in three facies associations fluvial channel belt overbank and floodplain floodplain pond coal bearing permian siliciclastics are interpreted as meandering river deposits in a foreland basin with subsidence generated by thrust sheet loading from at least three basin margins these sediments pass abruptly but conformably upwards into coal barren sandstones and conglomerates and siltstones interpreted as braided river deposits two basalt flows occur within the coal barren succession a recently published precise ar ar age of 250 3 0 7 ma for the lower of these basalts

the carbon and sulfur cycles and atmospheric oxygen from middle permian to middle triassic the results of a theoretical isotope mass balance model are presented for the time dependence of burial and weathering plus degassing fluxes within the combined long term carbon and sulfur cycles averaged data for oceanic 13c and 34s were entered for every million years from 270 to 240 ma middle permian to middle triassic to study general trends across the permian triassic boundary results show a drop in the rate of global organic matter burial during the late permian and a predominance of low values during the early to middle triassic this overall decrease with time is ascribed mainly to epochs of conversion of high biomass forests to low biomass herbaceous vegetation resulting in a decrease in the production of terrestrially derived organic debris additional contributions to lessened terrestrial carbon burial were increased aridity and a drop in sea level during the late permian which led to smaller areas of low lying coastal wetlands suitable for coal and peat deposition mirroring the drop in organic matter deposition was an increase in the burial of sedimentary pyrite and a dramatic increase in the calculated global mean ratio of pyrite s to organic c high s c values resulted from an increase of deposition in marine euxinic basins combined with a decrease in the burial of low pyrite associated terrestrial organic matter the prediction of increased oceanic anoxia during the late permian and early triassic agrees with independent studies of the composition of sedimentary rocks weathering plus burial fluxes for organic carbon and pyrite sulfur were used to calculate changes in atmospheric oxygen the striking result is a continuous drop in o2 concentration from 30 to 13 over a twenty million year period this drop was brought about mainly by a decrease in the burial of terrestrially derived organic matter but with a possible contribution from the weathering of older organic matter on land it must have exerted a considerable influence on animal evolution because of the role of o2 in respiration some examples are the extinction of many vertebrates loss of giant insects and amphibians and the restriction of animals to low elevations it is concluded that the extinction of plants may have contributed to the extinction of animals

tectonics of the pliocene homs basalts syria and implications for the dead sea fault zone activity timing of activity along the yammuneh segment lebanon syria of the dead sea fault zone and its northward continuation is still a subject of controversy our field structural analysis and observations on radar landsat and digital elevation model imagery of the homs region syria are of concern for plio quaternary tectonics of the whole northern part of the dead sea fault zone we show in this paper that the northern dead sea fault zone has remained active since the onset of the homs basalts at c 6 ma continuing movement in recent times is indicated by the occurrence of quaternary pull apart structures and offset of active ravines along the fault the homs basalts are related to the distinct oval shaped shin volcanic edifice of which the long axis trends nw the volcano was fed through nw striking tension fractures which now form dykes and volcanic ridges these patterns are consistent with a ne sw extension that occurred c 6 ma ago the northwestern end of the shin volcano is left laterally displaced c 20 km yielding a c 3 3 mm a 1 mean rate of relative movement between the arabian and african plates in the northern part of the dead sea fault zone the overall trace of the main active dead sea fault zone is not a single transform but forms an irregular plate boundary composed of transform fault and collision belt segments fine grained mylonite developed in the fault corridor may have favoured aseismic deformation in the shin volcano area

updated gondwana permian cretaceous earth history of australia abstract permo carboniferous glaciation confined to icecaps and mountain glaciers was followed by permian coal measures and early triassic barren measures and redbeds in the east terminally deformed in the mid triassic coal deposition resumed during the late triassic and tholeiite was erupted in the southeast after rifting the western margin was formed by the opening of the indian ocean at 156 and 132 ma at 140 ma a brief glaciation affected central australia by the 99 ma mid cretaceous the southern margin was finally shaped by the opening of the southeastern indian ocean the shoreline retreated to the present coast from the maximum aptian shoreline of an epeiric sea and the eastern highlands were uplifted to produce the present morphology of australia new data relate to the permo carboniferous and early cretaceous glaciations the kiaman reversed paleomagnetic interval events about the permian triassic boundary including possible impact craters advances in palynology invertebrate paleontology macrofloral paleontology and paleobiogeography the provenance of sediments by u pb ages and host rock affinity of zircons stable isotopes and biomarkers in petroleum systems coal environments calibrating the time scale with u pb ages of zircons fission track thermotectonic imaging geothermal energy and terranes split off the western margin

land plant diversity and the end permian mass extinction the permian and triassic represent a time of major global climate change from icehouse to hothouse conditions and significant 25 northward motion of landmasses amalgamated in essentially one supercontinent pangea the greatest of all mass extinctions occurred around the permian triassic boundary 251 ma although there is no consensus regarding the cause s recent studies have suggested a meteor impact and worldwide die off of vegetation on the basis of sparse local observations however new analyses of global permian and triassic plant data in a paleogeographic context show that the scale and timing of effects varied markedly between regions the patterns are best explained by differences in geography climate and fossil preservation not by catastrophic events caution should be exercised when extrapolating local observations to global scale interpretations at the other extreme global compilations of biotic change through time can be misleading if the effects of geography climate and preservation bias are not considered

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

clay mineralogical characteristics at the permian triassic shangsi section and their paleoenvironmental and or paleoclimatic significance abstract high resolution clay mineralogical investigations were conducted on the permian triassic p tr carbonate and siliceous rocks from the shangsi section south china the clay mineralogy is dominated by illite and illite smectite mixed layers i s throughout the sampled section with subordinate chlorite and vermiculite emerging from bed 24 approaching the end permian mass extinction horizon epme onwards positive correlations of clay fraction with mainly land derived tio2 and magnetic susceptibility ms indicate a primary continental origin of the clay minerals rock eval pyrolysis analysis palynomorph coloration scanning electron microscope sem and transmission electron microscope tem observations all suggest that the rocks experienced thermal diagenesis which mainly promotes illitization processes of smectite clay minerals while discrete clay minerals are merely affected despite this diagenetic effect clay minerals still carry valuable paleoenvironmental and paleoclimatic information in the shangsi section the overall illitic composition of the clay minerals and nearly absence of kaolinite suggest a general semi arid condition during the p tr interval appearance of chlorite from bed 24 onwards suggests further aridification compared to the late permian occurrence of vermiculite from beds 24 28 in association with abundant volcanogenic materials most negative 13ccarb values as well as enhanced soil derived moretane abundance suggests catastrophic soil erosion and likely soil acidification during the p tr transition in the source area s in relation with the active volcanism in that time further decrease of chemical weathering and increase of physical weathering are indicated by increased input of primary clay minerals such as chlorite a better illite crystallinity and increase of al2o3 tio2 ratios a climate cooling period corresponding to the clarkina changxingensis clarkina deflecta conodont zone to the lower clarkina zhangi conodont zone is indicated by higher abundance of illite lower terrigenous tio2 ms and al2o3 tio2 in comparison with the overlying uppermost permian strata

deposition floral composition and sequence stratigraphy of uppermost triassic rhaetian coastal coals southern sweden abstract two uppermost triassic rhaetian coal beds a and b bed bjuv member southern sweden deposited at the margin of the danish basin were investigated in order to interpret the peat forming environments in a sequence stratigraphic context and to establish the peat forming vegetations of the precursor mires peat formed close to the coastline and was governed by base level watertable rise linked to relative sea level rise which is emphasized by rare occurrences of marine phytoplankton micrhystridium lunnomidinium scaniense and rhaetogonyaulax rhaetica in the b bed a maximum flooding surface mfs7 between the coal beds a and b shows that peat accumulation occurred as a coastal response to the continued transgression of the danish basin that culminated with deposition of the coal bearing bjuv member the lower b bed accumulated in a transgressive systems tract tst and the upper a bed in a highstand systems tract hst the b bed consists of coal and coaly mudstone intervals showing that peat formation repeatedly was outpaced by relative watertable rise the huminite rich coal intervals indicate peat formation under oxygen deficient stagnant water conditions where the peat accumulation rate balanced the watertable rise overall low ts values indicate a freshwater mire the base of coal bed b marks the start of a relative decrease in creation of accommodation space and the surface between the sediments and coal bed b represents a terrestrialisation surface tes the palynofloral composition suggests that the initial mire was characterised by dipterid dicksoniacean tree ferns and marattialean ground ferns and few canopy trees dominated by cupressacean taxodiacean wet loving conifers with subordinate bennettitalean and caytonialean trees the coal intervals in the b bed represent terrestrialisation situations characterised by a reduced ratio of accommodation rate peat accumulation rate the palynology of these intervals indicates establishment of canopy trees primarily cupressacean taxodiacean conifers accompanied by bennettitaleans and caytonialeans with an understory of marattialean ground ferns and rarer tree ferns flooding surfaces fs and accommodation reversal surfaces ars in the b bed reflect changes in the rate of watertable rise the coaly mudstone intervals represent paludification situations with an upward increasing ratio of accommodation rate peat accumulation rate in general the palynology of the b bed suggests a coal floral composition that was dominated by mid and upper canopy plants consisting of cupcressaceaen taxodiaceaen trees probably occupying areas with standing water while ginkgos cycads bennettiales and caytoniales and other seed ferns grew in less wet areas understory plants were less abundant whereas a ground cover of ferns mainly of the families marattiales and osmundales as well as lycophytes may have been pronounced the upper surface of the b bed is a give up transgressive surface guts above which peat accumulation was replaced by siliciclastic deposition the palynofloral composition suggests an open mire dominated by ground ferns and probable tree ferns with minor bennettitalean and caytonialean mid canopy trees and with hardly any upper canopy trees the a bed is considerably richer in inertinite compared to the b bed the palynofloral and petrographic change correlates with an increase in fire activity across the triassic jurassic boundary and deforestation of the early jurassic mires

isotopic reconstruction of past continental environments abstract vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments to interpret these records a greater understanding of isotopic sources as well as fractionations associated with animal physiology soil geochemistry and diagenesis has been essential tooth enamel and fish otoliths yield subannual records of surface environments whereas soil minerals may integrate signals over many thousands of years carbon isotope variations in fossil vertebrates and soils record changes in the structure of vegetation and the isotope composition and concentration of atmospheric co2 oxygen isotope variations may be indirectly related to climate through reconstruction of the oxygen isotope composition of meteoric water or directly related to temperature through application of oxygen isotope paleothermometry to soil minerals or otoliths in africa nitrogen isotope variations show promise as a proxy for rainfall abundance though the gen

detailed correlation and age of continental late changhsingian and earliest triassic beds implications for the role of the siberian trap in the permian triassic biotic crisis abstract conchostracan rich beds between the siberian trap flood basalts and within the thick underlying hungtukun tuffs of the tunguska basin can be closely correlated with conchostracan faunas of dalongkou nw china and the germanic basin the germanic basin faunas in turn can be closely correlated with the marine international stratigraphic time scale and the accuracy of the biostratigraphic correlation of the permian triassic boundary ptb is confirmed by a minimum in 13ccarb values at this level these high resolution correlations demonstrate conclusively that the ptb is located within the temporally brief but thick siberian trap flood basalt sequence the ptb lies slightly above the level of the main permo triassic extinction event in low latitude marine beds which occurred at the base of the c meishanensis h praeparvus conodont zone and correlates with the beginning of the siberian trap flood basalt event the main end permian continental extinction event was somewhat earlier within the middle of the c changxingensis c deflecta conodont zone this horizon marks a mass extinction that devastated a diverse conchostracan fauna and left only low diversity faunas at low and high latitudes this continental extinction event horizon lies within the middle of the hungtukun tuffs of the tunguska basin and 107 m above the base of the guodikeng formation at dalongkou nw china a triassic type pioneer flora with numerous lycopod spores appears immediately above this level severe high northern and southern latitude marine extinctions occurred concurrently with this continental event but low latitude marine biota was not then affected this earlier event is best explained by global warming the main low latitude extinction event in marine warm water faunas occurred somewhat later and left no signature in high latitude marine faunas or in continental faunas but it does coincide with a rapid collapse of tropical rain forest environments disappearance of the highly diverse gigantopteris flora this collapse likely was caused by global cooling due to a volcanic winter event

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

palaeosol stratigraphy across the permian triassic boundary bogda mountains nw china implications for palaeoenvironmental transition through earth s largest mass extinction abstract upper permian and lower triassic palaeosols from northeastern tethyan localities exposed within the bogda mountains nw china provide a wealth of information regarding long term palaeoclimatic and palaeoenvironmental variations wuchiapingian palaeosols are characterized by intense redoximorphy accumulation of vascular plant matter accumulation of clay minerals and fe oxides slickensides and clastic dikes suggesting a soil moisture regime that ranged from perennially wet to distinctly seasonal in soil moisture budget changsinghian to early induan palaeosols include subsurface accumulations of clay and carbonate as well as surficial accumulations of organic matter indicative of sub humid to sub arid soil moisture and variable soil moisture regimes induan to olenekian palaeosols contain pedogenic caco 3 accumulations and gypsum pseudomorphs indicating a drier environment characterized by net soil moisture deficiency elemental composition of palaeosol matrix was used to estimate palaeoprecipitation through the chemical index of alteration minus potassium cia k proxy estimates from various wuchiapingian strata indicate relatively stable palaeoprecipitation during the late changsinghian and early induan palaeoprecipitation appears to have decreased from 1100 to 230 180 mm year over less than 100 m of vertical stratigraphic section in the induan and olenekian palaeoprecipitation appears much less stable than in wuchiapingian with values vacillating from 290 to 1014 mm year the transition to a relatively unstable precipitation state coincides generally with the permian triassic boundary and may reflect climatic disturbances associated with the end permian extinction event in addition to altered atmospheric circulation patterns resulting from regional tectonics moisture availability and expansion of the subtropical high pressure belt

pore fluid effects on s wave attenuation caused by wave induced fluid flow we studied seismic attenuation of p and s waves caused by the physical mechanism of wave induced fluid flow at the mesoscopic scale stress relaxation experiments were numerically simulated by solving biot s equations for consolidation of 2d poroelastic media with finite element modeling the experiments yielded time dependent stress strain relations that were used to calculate the complex moduli from which frequency dependent attenuation was determined our model consisted of periodically distributed circular or elliptical heterogeneities with much lower porosityandpermeabilitythan thebackgroundmedia which contained 80 of the total pore space of the media this model can represent a hydrocarbon reservoir where the porous background is fully saturated with oil or gas and the low porosity regions are always saturated with water three different saturation scenarios were considered oil saturated 80 oil 20 water gas saturated 80 gas 20 water and fully water saturated media varying the dry bulk and shear moduli in the background and in the heterogeneities a consistent tendency was observed in the relative behavior of the s wave attenuation among the different saturation scenarios first in the gas saturated media the s wave attenuation was very low and much lower than in the oil saturated or in the fully water saturated media second at low frequencies the s wave attenuation was significantly higher in the oil saturated media than in the fully water saturated media the p wave attenuation exhibited a more variable relative behavior among the different saturation degrees based on the mechanism of wave induced fluid flow and on our numerical results we suggest that s wave attenuation could be used as an indicator of fluid content in a reservoir additionally we observed that impermeable barriers in the background can cause a significant increasein s waveattenuation thissuggests that s wave attenuation could also be an indicator of permeability changes in a reservoir due to for example fracturing operations

δ13c depth profiles from paleosols across the permian triassic boundary evidence for methane release stable carbon isotopic analyses of organic carbon 13 c in individual paleosol profiles from permian triassic sequences of antarctica reveal systematic isotopic variations with profile depth these variations are in many cases analogous to those in modern soils which are functions of redox conditions soil development and degree and type of microbial decay in modern soils these isotopic depth functions develop independently from vegetation changes c 3 versus c 4 vegetation and can be diagnostic of soil orders this study shows that soil intrinsic functions can be preserved in the 13 c values of paleosols as old as 260 ma and constitute valuable data for paleoecological interpretations a large carbon isotopic offset of as much as 10 in whole paleosol profiles across the permian triassic boundary indicates significant changes in the soil biogeochemistry and the soil atmosphere system early triassic paleosols are distinctive in their extremely low 13 c values to 42 and often show an anomalous 13 c depth distribution compared to both permian paleosols and modern soils highly depleted 13 c values as the ones in early triassic paleosols are suggested to be associated with microbial methane oxidation methanotrophy this hypothesis implies increased methane concentrations in the early triassic soil atmosphere system increased atmospheric methane was probably partly responsible for the global carbon isotopic shift documented in marine and terrestrial sediments across the permian triassic boundary

evidence for long term climate change in upper devonian strata of the central appalachians abstract the highest 1 to 200 m of the upper devonian famennian catskill and equivalent hampshire formations exhibit a noticeable vertical or stratigraphic change in color and a shift in lithologic character the lower part of the unit is characterized by typically red channel phase sandstones and overbank siltstone and mudstone containing thin calcareous paleosols these lithologies give way to greenish gray sandstone containing abundant coaly plant fragments coalified logs and pyrite interbedded with thick intervals of non calcareous paleo vertisols the increase in the prominence of preserved terrestrial organic matter suggests that there was a corresponding increase in the abundance of plants in terrestrial ecosystems the stratigraphic change in lithology within the upper part of the catskill hampshire succession suggests the onset of environmental conditions that became increasingly wet in response to elevated humid climatic conditions during the final stages of catskill alluvial plain deposition the sedimentological signature suggesting increased climatic wetness within the uppermost catskill and hampshire formations is nearly contemporaneous with the initiation of late devonian gondwanan glaciation in the paleo high latitudes the appalachian climate record indicates that this change began during the fa2c and continued through the latest famennian reaching its peak during the fa2d when glacial deposits are recorded in the paleo mid latitudes of the appalachian basin evidence of this late famennian increase in precipitation also is recorded in the adjacent marine environments equivalent age marine units in ohio and kentucky record progressive increases in both total organic carbon and the percentage of terrestrially derived organic carbon this suggests that there was a late famennian increase in terrestrial organic matter productivity and that during the late famennian there were elevated levels of runoff produced by the interpreted increase in precipitation that washed progressively higher amounts of terrestrial organic matter into the local marine environments the late famennian climate changes identified within the appalachian basin strata have been recognizable globally and appear to have had both positive and negative effects on the earth s biota some marine groups exhibit sharp diversity drops or even extinction coincident with the maximum development of the late famennian ice age conversely terrestrial biota appears to have been more positively affected by the late famennian increased wetness that accompanied this progressive climate change marked diversification and evolutionary innovation which appear to coincide with this climatic deviation can be recognized within terrestrial plant communities and early tetrapod amphibians

early triassic induan olenekian conodont biostratigraphy global anoxia carbon isotope excursions and environmental perturbations new data from western australian gondwana the early triassic induan olenekian stage boundary dienerian smithian sub stage boundary has been identified at a depth of 2719 25m in the petroleum exploration well senecio 1 located in the northern perth basin western australia conodont faunas represent three conodont zones in ascending order the neospathodus dieneri zone the neospathodus waageni eowaageni zone and the neospathodus waageni waageni zone the induan olenekian dienerian smithian boundary is placed at the base of the neospathodus waageni eowaageni zone equivalent to the first appearance of neospathodus ex gr waageni utilised elsewhere and adopted by the iugs ics triassic subcommission to define the base of the olenekian bulk kerogen 13c carbon isotopes define a positive peak of c 4 per mille that essentially coincides with the induan olenekian boundary as seen in proposed global stratotype sections and points gssps in south china and spiti india demonstrating the global utility of this level for correlation an anoxic zone is recognised in the lower part of the senecio 1 core and the upper limit of this zone is dated as late induan late dienerian temporal and spatial mapping of marine anoxia and dysoxia globally demonstrates that pulses of dysoxia anoxia affected shallow marine zones at different times in different locations dysoxia anoxia in the shallow marine environment appeared in the latest permian at the extinction level later than in the deep marine environment and appears to be largely restricted to the induan griesbachian and dienerian and early olenekian smithian temporally and geographically restricted upwelling of an oxygen minimum zone into the ocean surface layer due to environmental perturbations including extreme global warming increased terrestrial chemical weathering intensity and continental erosion sea level rise and changes in marine nutrient inventories and productivity rates is interpreted as a likely cause of observed variation in shallow marine dysoxia anoxia in the early triassic

the effect of global warming and global cooling on the distribution of the latest permian climate zones abstract the end permian biotic crisis is commonly associated with rapid and severe climatic changes these climatic changes are commonly suggested to have originated from solid earth carbon degassing leading to global warming but aerosol and ash induced cooling induced by lava degassing has been suggested as well the application of an earth system model of intermediate complexity has enabled a visualisation of the major climatic shifts on the supercontinent pangaea caused by rapid temperature changes due to changed radiative properties from greenhouse gases the reconstructed reference climate was validated by latest permian climate indicative sediments to investigate the possible climatic shifts from a set of 22 reconstructions which varied with temperature a minimum global annual mean temperature of 18 2 c for the late permian climate prior to the climatic perturbation event was determined starting from this pre event setup global warming and global cooling scenarios were simulated the response of the end permian climate system to temperature increase and decrease show marked differences while global cooling is followed by major climatic changes in the high latitudes and replacement of boreal biomes by tundra and polar frost the changes during global warming are less pronounced with only locally increasing aridity compensated by humidisation in other regions the different behaviour of the climatic belts under warm and cold conditions is accompanied by different climate sensitivities caused by different strength of the snow cover albedo feedback thus changes in the energy balance of the latest permian surface troposphere system have a 30 higher perturbation potential during cold climate conditions than during warmhouse conditions therefore substantial global cooling resulting in coldhouse climate conditions and an annual global mean temperature below 18 c is more efficient in perturbing the earth palaeoclimate during the end permian warmhouse the results suggest that global cooling mechanisms as injection of sulphur aerosols and ash particles from the siberian traps large igneous province into the late permian palaeoatmosphere have a higher climate perturbation potential than a warming due to carbon greenhouse gases with a similar magnitude of radiative forcing

stable carbon isotope record of terrestrial organic materials for the last 450 ma yr abstract the timing and magnitude of carbon isotope excursions is essential for understanding the global transfer of carbon among the oceansland and atmosphere numerous studies have focused on data collection of stable carbon isotopes 13c from marine sediments and by extension to the atmosphere but many fewer systematic studies have been conducted on land plants over long time intervals we pursued three approaches to determining stable carbon isotope trends for the past 450 ma yr from c3 plants 13cp in 5 ma yr time steps first a compilation of 6888 13cp values from ten carbon sources from the literature average 24 6 1 7 isoorg data base the second approach assumes the 13cp is controlled primarily by the 13c of atmospheric co2 13ca and subsequent isotopic fractionation from diffusion and carboxylation during photosynthesis mod1 the third approach assumes changes in atmospheric co2 concentration pco2 causes physiological driven isotopic fractionation during photosynthesis when pco2 is greater than average holocene conditions mod2 compared to isoorg and mod1 mod2 reveals lower 13cp by up to 6 during periods when pco2 is elevated as secular governors of 13cp the 13ca and pco2 are most influential when they are directional and amplify the isotopic signal despite potential influences from local and regional environmental conditions and averaging the 13cp of multiple plant sources in many of the 5 ma yr age bins ten positive carbon isotopic excursions pcies are identified in isoorg of this study most of the excursions occurred during cool to glacial conditions or ocean anoxic events one prominent negative isotopic excursion ensued from 260 to 240 ma yr which may have been a response to oxidation of light c methane outbursts volcanic eruptions or bolide impact

the changing climate framework and depositional dynamics of triassic carbonate platforms from the dolomites abstract the triassic of the dolomites offers a valuable opportunity to investigate the relationships between climate fluctuations and the changing depositional dynamics of carbonate platforms the reconstruction of the large palaeoclimatic modification is based on the synthesis of multiple sedimentological palaeobotanical pedological and geochemical proxies the triassic climate fluctuations were generally fast in nature and were probably associated with a latitudinal shift of the monsoon belts during the triassic the dolomites were placed at an intertropical northern latitude of about 16 18 and were generally dominated by dry climate and elevated temperature at least five pulses toward moister climate are however documented dated to early olenekian middle anisian late ladinian middle carnian and late norian times within this variable climatic scenario the carbonate systems record a global evolutionary trend from late permian early triassic regional shelves rich in loose micrites and bio calcarenites to anisian ladinian synsedimentary cemented steep sided 35 40 high relief platforms and back to carnian low angle ramps moist transgressive episodes were surprisingly prone to the spreading of corals and other colonial reef organisms probably because of the reduced space competition by syndepositional cementation structures the permo triassic boundary extinction dramatically impacted on the calcified organism communities but the carbonate depositional architecture nevertheless stayed almost unaffected through the boundary the early triassic and earliest anisian were commonly associated with hyperhaline sometimes evaporitic conditions intervals of moister climate and efficient river discharge are however documented by earliest induan and early olenekian sediments the latter terrigenous deposits matched a crisis in the carbonate production after a return to arid conditions during the anisian a fluctuation toward moister climate developed associated to a massive continental vegetation cover the anisian tectonic activation of the region fragmented the previous carbonate shelf triggering the development of three generations of fast prograding but globally backstepping isolated platforms recording an increasing role of the synsedimentary cementation a dry climate dominated the late anisian and early ladinian interval at the time a fast subsidence pulse was associated with platform drowning and basinal anoxia only a few aggrading pinnacles were able to survive providing the nuclei for larger prograding platforms during a dry climate interval massive syndepositional cementation generated a major source of carbonate carbonate production stayed active through the ladinian magmatic phase but the onset of volcanism was associated with a large modification in the platform carbonate facies which became dominated by automicrites moist climate phases are well documented again during the late ladinian followed by a return to dry conditions the late ladinian early carnian platforms prograded toward the eastern dolomites depocentre eventually infilling almost the whole of the accommodation space the middle portion of the carnian recorded renewed sharply moist phases associated with the demise of the rimmed platforms and with the return to loose sediment ramps at least four separated humid fluctuations can be identified in this carnian interval alone climate then returned to persistent aridity until the late norian moist phase

mixed continental marine biotas following the permian triassic mass extinction in south and north china abstract correlation between marine and continental permian triassic p tr strata is crucial for full understanding of the nature of this global extinction event but it has proved difficult to achieve here we show that two sections in south china and north china record similar mixed continental marine biota in the post extinction stratigraphic interval including conchostracans plants insects marine bivalves and lingulid brachiopods in addition the continental p tr mass extinction was represented by a sharp decrease in the diversity and abundance of the gigantopteris flora in south china but eliminated the palaeozoic type conifer flora and herbivorous pareiasaurs in north china these mixed continental marine biota provide the biological evidence for stratigraphic correlation between marine and continental p tr transitional beds in south china and north china especially the co occurrence of the pteria towapteria eumorphotis bivalve assemblage and the euestheria gutta bearing conchostracan fauna or euestheria gutta magniestheria mangaliensis palaeolimnadiopsis vilujensis conchostracan assemblage we propose that these specific marine bivalve and continental conchostracan assemblages could be considered as markers of p tr transitional beds in marine continental siliciclastic settings

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

middle triassic paleosols and paleoclimate of antarctica abstract the lashly formation in the allan hills of southern victoria land antarctica is now at a latitude of 76 s and during the middle triassic was at least 70 s the combined evidence of fossil roots and soils indicates a paleoclimate unusual for such a high latitude temperate paleotemperature is indicated by roots logs and leaves of woody plants and the degree of chemical weathering and clay formation within the paleosols paleosols of the lashly formation are more like soils of southern sweden than those of either finland or southern europe silt infiltration structures around root traces and in cracks within the paleosols are evidence for a seasonally snowy climate but there is no evidence of ice wedges or other permafrost features in the paleosols other evidence of climatic seasonality includes well defined growth rings in fossil wood and abscission scars at the base of fossil leaves diverse broadleaf plants and noncalcareous paleosols indicate a humid climate with mean annual precipitation of about 1200 mm such a wet climate is anomalous for the interior of the supercontinent of pangea and such a warm and mildly seasonal climate is anomalous for such high latitudes this paleoclimatic anomaly may be a lingering effect of global greenhouse initiated at the permian triassic boundary paleoclimatic variables calculated here may be useful for recalibrating global paleoclimatic models for the middle triassic

catastrophic soil erosion during the end permian biotic crisis organic geochemical analyses of sedimentary organic matter from a marine permian triassic transition sequence in northeastern italy reveal a significant influx of land derived diagenetic products of polysaccharides this unique event reflects massive soil erosion resulting from destruction of land vegetation due to volcanogenic disturbance of atmospheric chemistry the excessive supply of soil materials to the oceans provides a direct link between terrestrial and marine ecological crises suggesting that ecosystem collapse on land could have contributed to the end permian marine extinctions

permian triassic boundary in the central transantarctic mountains antarctica the permian triassic boundary occurs within a relatively complete terrestrial sequence in the shackleton glacier area of the central transantarctic mountains the boundary is within a 7 to 10 m thick interval between the permian glossopteris flora and the lower triassic lystrosaurus fauna this interval representing on the order of 200 k y records some of the events that occurred in the transition from the permian to triassic in the best documented section at graphite peak in the beardmore glacier region protohaploxypinus microcorpus zone palynomorphs which we assign to the latest permian record the declining glossopteris flora and occur near the top of the buckley coal measures just below a previously reported major negative 13c excursion in the shackleton glacier area the permian glossopteris flora including fossil wood roots and leaves occurs within the lower part of the fremouw formation the antarctic lystrosaurus assemblage of early triassic age has several species in common with the south african fauna that lived 20 to 35 closer to the equator the migration of vertebrates from southern africa into antarctica in the early triassic supports hypotheses of runaway greenhouse warming possibly related to co2 emissions from siberian flood basalts and large methane gas releases changes in flora bracketing the first of the major negative 13c anomalies near the boundary in antarctica and in east greenland support the hypothesis that a global event perhaps through mutations caused by enhanced ultraviolet radiation may have played a role in the destruction of floras

geobiology and palaeogenomics abstract geobiology is centered on interactions of the biosphere with the atmosphere hydrosphere and lithosphere in deep time geobiology has focused on critical intervals of change for earth and its biota such geobiological studies include data from palaeobiology geochemistry and sedimentary geology within an interdisciplinary framework palaeogenomics has a variety of research agendas and one of them is to understand the genes involved in key changes in the evolutionary history of life and when those genes and their interactions first evolved the combination of geobiology and palaeogenomic studies is a powerful approach which leads to a more fundamental understanding of how earth and life have changed through time for example linking palaeogenomic studies of biomineralization genes in modern organisms and when they first evolved in the cambrian with geobiological studies of the impact this had on the production of carbonate sedimentary facies such as encrinites and the development of the neritan ocean provides a unique perspective on how genes have shaped formation of the sedimentary record another component of the cambrian explosion the evolution of vertical bioturbation at the start of the cambrian has had significant effects on biogeochemical cycling and sediment production and provides an inviting target for future genomic studies the remaining phanerozoic includes a broad variety of evolutionary innovations which within a joint geobiological and palaeogenomic context can also be profitably studied in pelagic environments the genomic changes leading to evolution of the calcium carbonate biomineralized skeletons of coccolithophores contributed to the widespread deposition of carbonate sediment in deep settings and development in the mesozoic of the cretan ocean on land linking palaeogenomic studies of the genes that led to the palaeozoic evolution of lignin and their associated geobiological effects such as deposition of coal provide another example of the effects of genes upon development of the sedimentary record such work will ultimately provide a history of genomic change and the environmental factors that influenced it as well as how genomic change influenced environments

global warming leads to early triassic nutrient stress across northern pangea the largest extinction in earth history in the latest permian was followed throughout most of the early triassic by a prolonged period of ecologic recovery what factors delayed biotic recovery are still under debate and partly revolve around impacts of global warming on primary marine productivity we examined n isotope records from the festningen section on spitsbergen to examine changes in nutrient availability through the early to middle triassic along the northern margin of pangea our results show progressive decline in n availability throughout the griesbachian leading to severe nutrient limitations through the remainder of the early triassic until returning to a highly productive continental margin in middle triassic time these results are consistent with other studies from northern and western pangea and thus show regional nutrient limitations occurred in what should have been the main zone of marine primary productivity such nutrient limitation likely stressed primary production and consequently contributed to prolonged marine recovery we suggest this was driven by high ocean temperatures depressing the marine nutricline

the timing and pattern of biotic recovery following the end permian mass extinction the aftermath of the great end permian period mass extinction 252 myr ago shows how life can recover from the loss of 90 species globally the crisis was triggered by a number of physical environmental shocks global warming acid rain ocean acidification and ocean anoxia and some of these were repeated over the next 5 6 myr ammonoids and some other groups diversified rapidly within 1 3 myr but extinctions continued through the early triassic period triassic ecosystems were rebuilt stepwise from low to high trophic levels through the early to middle triassic and a stable complex ecosystem did not re emerge until the beginning of the middle triassic 8 9 myr after the crisis a positive aspect of the recovery was the emergence of entirely new groups such as marine reptiles and decapod crustaceans as well as new tetrapods on land including eventually dinosaurs the stepwise recovery of life in the triassic could have been delayed either by biotic drivers complex multispecies interactions or physical perturbations or a combination of both this is an example of the wider debate about the relative roles of intrinsic and extrinsic drivers of large scale evolution from a much more devastated planet and biota than the others with only some 10 of species surviving the epme was much harsher than the other mass extinctions during which global species diversity reduced to only about 50 of the pre extinction total 1 2 24 26 this means that the triassic recovery has two profound implications first it may show qualitative as well as quantitative differences from the other post extinction recoveries and second it can act as an exemplar of what to expect at its most extreme when global biodiversity is pushed to the brink there are obvious implications for current concerns about biodiversity loss and recovery resulting from human impacts 27 28 in the past ten years attention has focused on the sedimentary successions in south china these are enormously laterally extensive with some formations extending more than 2 000 km from the zhejiang to yunnan provinces the huge exposures length of the sections and improving dating open up the opportunity to explore physical environmental and biotic changes through the extinction and recovery times in varied marine habitats and compare these with patterns elsewhere in the world fig 1 a fine scale forensic analysis of this extraordinary time in earth s history now becomes possible the end permian mass extinction the epme killed 80 96 of marine animal species and 70 of terrestrial vertebrate species

early triassic early olenekian life in the interior of east gondwana mixed marine terrestrial biota from the kockatea shale western australia abstract a new terrestrial marine assemblage from the lower beds of a thin outcrop section of the kockatea shale in the northern perth basin western australia contains a range of fossil groups most of which are rare or poorly known from the lower triassic of the region to date the collection includes spinose acritarchs organic cemented agglutinated foraminifera lingulids minute bivalves and gastropods ammonoids spinicaudatans insects austriocaridid crustaceans actinopterygians a temnospondyl like mandible plant remains and spores and pollen of these groups the insects crustaceans and macroplant remains are recorded for the first time from this unit palynomorphs permit correlation to nearby sections where conodonts indicate an early olenekian smithian age the locality likely represents the margin of an early triassic shallow interior sea with variable estuarine like water conditions at the southwestern end of an elongate embayment within the east gondwana interior rift sag system preserved along the western australian margin monospecific spinose acritarch assemblages intertwined with amorphous organic matter may represent phytoplankton blooms that accumulated as mats and suggest potentially eutrophic surface waters the assemblage represents a mixure of marine and terrestrial taxa suggesting variations in water conditions or that fresh brackish water and terrestrial organisms were transported from adjacent biotopes some of the lower dark shaly beds are dominated by spinicaudatans likely indicating periods when the depositional water body was ephemeral isolated or subjected to other difficult environmental conditions the biota of the kockatea shale is insufficiently known to estimate biotic diversity and relationships of individual taxa to their permian progenitors and triassic successors but provides a glimpse into a coastal zone from the interior of eastern gondwana specialist collecting is needed to clarify the taxonomy of many groups and comparisons to other lower triassic sites are required to provide insights into the pattern of biotic decline and recovery at the end permian crisis

palaeo environment in an ancient low latitude arid lacustrine basin with loessite the smith bank formation early triassic in the central north sea uk continental shelf acknowledgements this work was conducted as part of the triassic mudstones joint industry project which was sponsored by bp conocophillips eon e p esso exploration and production uk limited gdf suez e p uk ltd jx nippon maersk oil shell and total the guidance of prof steve hillier of the james hutton institute in quantitative mineralogical analysis is acknowledged with gratitude dr stuart jones and an anonymous referee are thanked for their incisive and constructive reviews that significantly helped in the revision of the manuscript

integrated sr isotope variations and global environmental changes through the late permian to early late triassic new 87sr 86sr data based on 127 well preserved and well dated conodont samples from south china were measured using a new technique la mc icpms based on single conodont albid crown analysis these reveal a spectacular climb in seawater 87sr 86sr ratios during the early triassic that was the most rapid of the phanerozoic the rapid increase began in bed 25 of the meishan section gssp of the permian triassic boundary ptb and coincided closely with the latest permian extinction modeling results indicate that the accelerated rise of 87sr 86sr ratios can be ascribed to a rapid increase 2 8 of riverine flux of sr caused by intensified weathering this phenomenon could in turn be related to an intensification of warming driven runoff and vegetation die off continued rise of 87sr 86sr ratios in the early triassic indicates that continental weathering rates were enhanced 1 9 times compared to those of the late permian continental weathering rates began to decline in the middle late spathian which may have played a role in the decrease of oceanic anoxia and recovery of marine benthos the 87sr 86sr values decline gradually into the middle triassic to an equilibrium values around 1 2 times those of the late permian level suggesting that vegetation coverage did not attain pre extinction levels thereby allowing higher runoff

perturbations in the carbon cycle during the carnian humid episode carbonate carbon isotope records from southwestern china and northern oman the carnian humid episode is an interval of prominent climatic changes in the late triassic we studied the carbon isotope 13c geochemistry of carbonates from sections in southwestern china and northern oman 13c records from the yongyue section western guizhou south china show a progressive positive shift from 1 4 to 2 8 in the early to middle julian 1 substage this positive trend is followed by a swift negative shift of c 4 2 from 2 8 to 1 4 in the julian 2 substage 13c from the wadi mayhah section northern oman shows a positive shift from 2 2 to 2 8 in the julian 1 substage followed by a negative shift of c 3 2 from 2 8 to 0 3 in the julian 2 substage the 13c records from the two study sections generally correlate well with each other as well as with published records pointing to a considerable input of isotopically light carbon starting in the late julian 1 substage such a large amount of light carbon probably derived from direct degassing and the sediment sill contact metamorphism of the panthalassan wrangellia large igneous province and contemporary tethyan volcanism the voluminous volcanogenic greenhouse gases probably contributed to the warming pulse in the middle carnian thus the dry wet climatic transition during the carnian humid episode is best interpreted as a warm climate driven intensification of the activities of the atmospheric circulation and hydrological cycle