the permo triassic transition in spitsbergen δ13corg chemostratigraphy fe and s geochemistry facies fauna and trace fossils new 13 c org analyses of two boundary sections between the late permian kapp starostin formation and the early triassic vardebukta formation of western spitsbergen confirm field evidence that their contact is a conformable one thus contrary to previous reports some spitsbergen sections contain a complete record of the environmental and faunal changes during the crisis interval of the end permian mass extinction no environmental deterioration is recorded in the late permian until near the end of the terminal changxingian stage whereupon the abundant siliceous sponge fauna of the kapp starostin formation disappears along with the deep burrowing fauna responsible for the zoophycus trace fossil a low diversity dysaerobic trace fossil assemblage is briefly developed before a transition to finely laminated pyritic facies immediately beneath the permo triassic boundary analysis of the s c ratios from the laminated strata suggests that free h 2 s was present in the water column euxinic conditions even in relatively nearshore settings subject to storm sandstone deposition the mass extinction crisis in spitsbergen is therefore coincident with the extensive development of oxygen poor conditions in the water column and compares closely both in timing and nature with the crisis seen in lower latitude tethyan settings however the subsequent aftermath and recovery in the boreal sections of spitsbergen was more rapid than in tethys thus a shoreface sandstone body within the dienerian stage contains an appreciable diversity of fauna by the standards of the early triassic including bryozoans calcareous algae and deep infaunal bivalves that suggests the marine ecosystem recovery began earliest in higher palaeolatitudes

palaeoenvironments and faunal recovery after the end permian mass extinction abstract strata of the lower triassic werfen formation dolomites northern italy record deposition in a wide range of palaeoenvironments from peritidal to outer ramp settings this enables accurate assessment of faunal recovery following the end permian mass extinction by eliminating facies related effects extinction of the shelly taxa appears to be rapid and occurs in the latest permian tesero oolite horizon disappearance of the various trace fossil taxa appears to be more gradual following the extinction the lower and middle griesbachian are characterised by laminated sediments containing low diversity bedding plane assemblages ichnological geochemical and sedimentological data show evidence of widespread low oxygen conditions normally oxygenated waters return in the late griesbachian and there is a moderate increase in tiering above and below the surface macrofaunal and ichnofossil diversity decrease markedly during the smithian with the appearance of more terrigenous strata possibly reflecting an increased run off and more brackish conditions complete recovery begins in the basal spathian with an increase in tiering above and below the substrate crinoids and ammonoids appear for the first time in the werfen formation and the ichnogenus rhizocorallium re appears global correlation is hindered by poor biostratigraphy in the dolomites region however on a broad scale it appears as though many of the palaeoenvironmental changes are repeated worldwide current available data suggest that the re appearance of some trace fossil taxa e g diplocraterion rhizocorallium may be globally synchronous

flourishing ocean drives the end permian marine mass extinction the end permian mass extinction the most severe biotic crisis in the phanerozoic was accompanied by climate change and expansion of oceanic anoxic zones the partitioning of sulfur among different exogenic reservoirs by biological and physical processes was of importance for this biodiversity crisis but the exact role of bioessential sulfur in the mass extinction is still unclear here we show that globally increased production of organic matter affected the seawater sulfate sulfur and oxygen isotope signature that has been recorded in carbonate rock spanning the permian triassic boundary a bifurcating temporal trend is observed for the strata spanning the marine mass extinction with carbonate associated sulfate sulfur and oxygen isotope excursions toward decreased and increased values respectively by coupling these results to a box model we show that increased marine productivity and successive enhanced microbial sulfate reduction is the most likely scenario to explain these temporal trends the new data demonstrate that worldwide expansion of euxinic and anoxic zones are symptoms of increased biological carbon recycling in the marine realm initiated by global warming the spatial distribution of sulfidic water column conditions in shallow seafloor environments is dictated by the severity and geographic patterns of nutrient fluxes and serves as an adequate model to explain the scale of the marine biodiversity crisis our results provide evidence that the major biodiversity crises in earth s history do not necessarily implicate an ocean stripped of most life but rather the demise of certain eukaryotic organisms leading to a decline in species richness

composition and structure of microbialite ecosystems following the end permian mass extinction in south china after the end permian mass extinction microbialites were widespread in the shallow marine environments in south china diverse microbialites are characteristic of the early triassic carbonate sequences their stratigraphic range is rather short just across the permian triassic p tr boundary and defined by conodonts n meishanensis h changxingensis and h parvus zones thus the p tr microbialites grew immediately after the first episode of the end permian mass extinction coinciding with the beginning of the conodont n meishanensis zone and ceased their growth at the beginning of the conodont i staeschei zone which occurred just before the second episode of the end permian crisis at meishan they include three main types stromatolites thrombolites and dendrites in south china the presence of abundant microbial remains of coccoid type and renalcis like microbes strengthens the previous view that the p tr microbialites are biogenic both cyanobacteria and other microbes have participated to construct the microbial ecosystems the thrombolite communities are dominated by the renalcis like microbes and foraminifers and also contain ostracods microgastropods and microconchids the stromatolite communities are dominated by coccoidal microbes with minor constituents of other undetermined microbes metazoans are rare the dendrolite assemblage contains few identifiable microfossils most of microbialite communities have a high abundance low diversity community structure characteristic of marine communities after the end permian mass extinction some metazoans of either opportunists or disaster forms dwelled in this special ecosystem the microbialite builders formed the primary producer communities and constructed the lowest level ecosystem structure the lower level ecosystem proliferated due to the collapse of the higher level of ecosystem structure characterized by benthic shelly and predator communities in the end permian crisis

anomalously diverse early triassic ichnofossil assemblages in northwest pangea a case for a shallow marine habitable zone early triassic trace fossil assemblages from the northwest margin of pangea record a diverse suite of postextinction infauna these ichnofossil assemblages occurred within well oxygenated shallow marine refuges in a panthalassa ocean otherwise characterized by widespread anoxia we propose an environmentally controlled model for their distribution in which wave aeration enhanced by frequent storms gave rise to an optimal zone for benthic colonization within this habitable zone extinction pressures were ameliorated and postextinction recovery duration was minimized

late pliocene establishment of exorheic drainage in the northeastern tibetan plateau as evidenced by the wuquan formation in the lanzhou basin abstract the fluvial archives in the upper reach yellow river basins provide important information about drainage history of the northeastern tibetan plateau tp associated with geomorphologic evolution and climate change however the pliocene fluvial strata within this region have not been studied in detail hence limiting the understanding of the late cenozoic development of regional fluvial systems in this paper we present the results of a study of the geochronology sedimentology and provenance of the fluvial sequence of the wuquan formation in the lanzhou basin in the northeastern tp magnetostratigraphic and cosmogenic nuclide burial ages indicate that the wuquan formation was deposited during 3 6 2 2 ma furthermore sedimentary facies gravel composition paleocurrent data and detrital zircon u pb age spectra reveal that the fluvial sequence resembles the terraces of the yellow river in terms of source area flow direction and depositional environment our results indicate that a paleo drainage system flowing out of the northeastern tp was established by ca 3 6 ma and that the upstream parts of the yellow river must have developed subsequently from this paleo drainage system the late pliocene drainage system fits well with the dramatic uplift of the northeastern tp an intensified asian summer monsoon and global increase in erosion rates which may reflect interactions between geomorphic evolution tectonic deformation and climate change

earliest triassic microbialites in curuk dag southern turkey composition sequences and controls on formation the permian triassic boundary sequence at curuk dag near antalya turkey begins with a major erosion surface interpreted as being the late permian lowstand on which lies ca 0 4 m of grainstone packstone composed of ooids peloids and bioclasts most ooids are superficial coats on fragments of calcite crystals presumed to be eroded from crystal fans which are no longer present the erosion surface is smooth and shows no evidence of dissolution the grainstone packstone contains intraclasts of the underlying wackestone proving erosion next are 15 m of microbialite comprised of interbedded stromatolites thrombolites plus beds of planar limestones with small scale erosion the latter comprise a complex interlayering of stromatolitic thrombolitic and peloidal fabrics and precipitated crystal fans which form a hybrid of microbialite and inorganic carbonate together with bioclastic debris and micrite the curuk dag microbialite sequence is repetitious the lower part is more complex with abundant stromatolites and hybrid microbialites some of the stromatolites are themselves hybrids composed of peloids and crystal fans in the upper part of the sequence stromatolites are missing and the rock is composed mostly of recrystallized thrombolites that develop upwards from tabular to domal form the domes form directly below small breaks in microbialite growth where very thin shelly micrites and grainstones packstones are deposited repetition of facies may be controlled by sea level change a deepening up model is consistent with the evidence stromatolites with abundant crystal fans dominate in shallower water deepening through hybrid microbialite and interlayered sediments to thrombolite probably no more than a few tens of metres deep followed by breaks and renewal of microbialite growth an interpretation of open marine fully oxygenated waters for microbialite growth is consistent with ongoing parallel work that has identified bairdioid ostracods in the microbialite a group known to be open marine however other researchers have proposed low oxygen conditions for permian triassic boundary facies globally so work continues to confirm whether the curuk dag microbialite grew in dysoxic or normally oxygenated conditions the principal stimulus for post extinction microbialites is likely to be carbonate supersaturation of the oceans the microbialite sequence is overlain by a further 25 m of grainstone packstone without microbialite followed by early triassic shales overall microbialites form a thin aggradational sequence during an overall relative sea level rise consistent with global eustatic rise following the late permian lowstand

trace fossil evidence for restoration of marine ecosystems following the end permian mass extinction in the lower yangtze region south china abstract unlike the high abundance low diversity macrofaunas that characterize many early triassic benthic palaeocommunities ichnofossils were relatively common in the aftermath of the end permian mass extinction worldwide ichnofossils therefore are a good proxy for ecosystem recovery after the end permian biotic crisis this paper documents 14 ichnogenera and one problematic form from lower triassic successions exposed in the lower yangtze region south china post extinction ichnodiversity remained rather low throughout the griesbachian early smithian period and abruptly increased in the late smithian however several lines of evidence including extent of bioturbation burrow size trace fossil complexity and tiering levels indicate that diversification of ichnotaxa in the late smithian did not signal full marine ecosystem recovery from the permian triassic p tr mass extinction marine ichnocoenoses did not recover until the late spathian in south china the marginal sea provided hospitable habitats for tracemakers to proliferate in the aftermath of the end permian mass extinction

wrinkle structures microbially mediated sedimentary structures common in subtidal siliciclastic settings at the proterozoic phanerozoic transition sedimentary structures produced by microbial activity are well known from ancient carbonate facies but little is known about equivalent microbial structures in ancient siliciclastic facies wrinkle marks and kinneyia ripples are closely related sedimentary structures that are commonly found in ancient siliciclastics and they may represent microbial activity to evaluate this possibility these structures were studied in vendian cambrian strata of north america and compared to structures formed by modern microbial mat communities in redfish bay texas striking similarities in sedimentologic petrographic and morphologic characteristics of modern and ancient occurrences suggest that the enigmatic but widespread ancient structures could have been formed by microbial processes the relative abundance of these structures in siliciclastic facies of this interval further suggests that prior to the onset of relatively intense bioturbation in the ordovician microbial mats could have played a significant role in the evolution and diversification of early life in a broad variety of sea floor environments

complete biotic and sedimentary records of the permian triassic transition from meishan section south china ecologically assessing mass extinction and its aftermath abstract the meishan section south china is the global stratotype section and point gssp for the permian triassic boundary ptb and is also well known for the best record demonstrating the permian triassic mass extinction ptme all over the world this section has also been studied using multidisciplinary approaches to reveal the possible causes for the greatest phanerozoic biocrisis of life on earth many important scenarios interpreting the great dying have been proposed on the basis of data from meishan nevertheless debates on biotic extinction patterns and possible killers still continue this paper reviews all fossil and sedimentary records from the permo triassic p tr transition based on previously published data and our newly obtained data from meishan and assesses ecologically the ptme and its aftermath to determine the biotic response to climatic and environmental extremes associated with the biocrisis eight updated conodont zones clarkina yini clarkina meishanensis hindeodus changxingensis clarkina taylorae hindeodus parvus isarcicella staeschei isarcicella isarcica and clarkina planata zones are proposed for the ptb beds at meishan major turnover in fossil fragment contents and ichnodiversity occurs across the boundary between bed 24e 5 and bed 24e 6 suggesting an extinction horizon in a thin stratigraphic interval the irregular surface in the middle of bed 27 is re interpreted as a firmground of glossifungites ichnofacies rather than the previously proposed submarine dissolution surface or hardground surface both fossil fragment contents and ichnodiversity underwent dramatic declines in beds 25 26a coinciding with metazoan mass extinction fossil fragment content ichnodiversity and all ichnofabric proxies including burrow size tiering level bioturbation level indicate that the p tr ecologic crisis comprises two discrete stages coinciding with the first and second phases of the ptme in meishan ecologic crisis lagged behind biodiversity decline during the ptme pyrite framboid size variations suggest that depositional redox condition was anoxic to euxinic in the latest changhsingian became euxinic in beds 25 26a turned dysoxic in bed 27 then varied from euxinic to anoxic through most of the griesbachian the 9 c increase in seawater surface temperature from bed 24e to bed 27 at meishan seems to result in dramatic declines in biodiversity and fossil fragment contents in beds 25 26a but had little effect on all ecologic proxies both metazoans and infauna seem not to have been affected by the pre extinction anoxic euxinic condition the anoxic event associated with the ptme may have occurred in a much shorter period than previously thought and is only recorded in beds 25 26a at meishan fossil fragment contents ichnofaunas ichnofabrics and pyrite framboid size all show that no signs of oceanic acidification and anoxia existed in bed 27 the early griesbachian anoxia may have resulted in rarity of ichnofauna and metazoans in the lower yinkeng formation in which the ichnofauna is characterized by small simple horizontal burrows of planolites and metazoan faunas are characterized by low diversity high abundance opportunist dominated communities the rapid increase of 9 c in sea surface temperature and a short anoxia or acidification coincided with the first pulse biocrisis while a prolonged and widespread anoxia probably due to a long period of high seawater temperate condition may be crucial in mortality of most organisms in the second pulse ptme marine ecosystems started to recover coupled with environmental amelioration in the late griesbachian

unusual shallow marine matground adapted benthic biofacies from the lower triassic of the northern paleotethys implications for biotic recovery following the end permian mass extinction abstract we report two shallow marine ichnofauna bivalve microbial mat biofacies from the lower triassic xiahuancang formation of the southern qilian area qinghai province northwestern china which was located at moderate high paleolatitudes on the northern margin of the paleotethys ocean paleoenvironmental analyses show that members i and ii of the xiahuancang formation represent a shoreface and a lower shoreface to offshore transition setting respectively biofacies 1 recognized from member i is characterized by a diverse ichnofauna including deep tiers of rosselia and diplocraterion claraia dominated bivalves and microbially induced sedimentary structures misss biofacies 2 in succeeding member ii is dominated by a diverse ichnofauna epifaunal and shallow infaunal bivalves and wrinkle structures primary co occurrences preservational features and palimpsest or crosscutting relationships of all components within the biofacies indicate that microbial mats bivalves and trace makers actively interacted with one another during deposition they largely represent contemporaneous biotic associations microbial mats are interpreted to have grown under well oxygenated conditions after storm deposition due to the association of deep tiering infauna and diverse epifauna as well as well developed cross stratification and the top layer of microbial mats could serve as an oasis for metazoans microbial mats not only proliferated in harsh environments but also coexist with epifauna and deep tiering infauna in well oxygenated settings following the end permian crisis their occurrences in the early triassic are unrelated to environmental stresses which are coincident with their sedimentologic record from other geological time intervals apparently the southern qilian ichnofauna bivalve microbial mat biofacies with juxtaposed epifauna infauna and miss or wrinkle related microbial mats represents a matground adapted benthic metazoan ecosystem in the earliest triassic which provided sufficient oxygen food and other hydrodynamic conditions hospitable for metazoans and ecosystems to recover and reached a fairly high level recovery stage 3 in a tough time when most biotas suffered biotic depletion and environmental stress the biotic components in unique biofacies may represent a phase shift community in siliciclastic settings during the early triassic

occurrence and biomarker potential of 23 methyl steroids in diatoms and sediments abstract 23 methyl sterols have been reported to be synthesized by a few marine algae but unambiguous identification of 23 methyl steroids in sediments and petroleum is lacking we report the presence of 23 methylcholesta 5 22e dien 3 ol in 14 out of 106 diatom cultures thereby showing that diatoms together with dinoflagellates may be an important environmental source for such steroids synthesis of authentic 23 methylcholestanes showed that their mass spectra are identical to those of 24 methylcholestanes but that they elute earlier on apolar stationary phases during gas chromatography gc analysis co injection of the authentic standards with sediment extracts revealed the presence of these compounds in the skole unit of the oligocene menelite formation the miocene monterey formation and the messinian vena del gesso formation in addition we tentatively identified 23 24 dimethyl 27 norcholestanes in some of these sediments molecular clock calculations suggest that diatoms are a possible source for 23 methyl steroids in sediments and petroleum from the late jurassic onwards

environmental controls on the post permian recovery of benthic tropical marine ecosystems in western palaeotethys aggtelek karst hungary climate warming during the late permian is associated with the most severe mass extinction event of the phanerozoic and the expansion of hypoxic and anoxic conditions in shallow shelf settings it has been hypothesised that wave aeration provided a habitable zone in the shallowest environments that allowed the survival and rapid recovery of benthic invertebrates during the early triassic we test this hypothesis by studying the rock and fossil records of the aggtelek karst hungary nearshore settings recorded in the bodvaszilas sandstone formation and units a and d of the szin marl formation are characterised by taxonomically homogenous fossil assemblages of low diversity and low evenness ecological and taxonomic recovery in this environmental setting was hampered by persistent environmental stress this stress is attributed to increased runoff related to climate warming during the early triassic that resulted in large salinity fluctuations increased sedimentation rates and eutrophication that led to seasonal hypoxia and an environment only favourable for opportunistic taxa in contrast shoal and mid ramp settings further offshore are characterised by high diversity faunas with a greater functional complexity prior to the late spathian tirolites carniolicus zone the shelly fossils and trace fossils are limited to settings aerated by wave activity which supports the habitable zone hypothesis in the tirolites carniolicus zone however the oxygen minimum zone retreats offshore and the habitable deeper shelf settings are rapidly colonised by shallow water taxa evidenced by the highest levels of diversity and bioturbation recorded in the study locally full recovery of marine ecosystems is not recorded until the illyrian with the establishment of a sponge reef complex

the criteria for the biogeneicity of microbially induced sedimentary structures miss in archean and younger sandy deposits abstract the identification of fossils or biogenic sedimentary structures in rocks of archean age is difficult because similar lithological features could rise from purely physical or chemical processes alone therefore it is important to define criteria that serve the secure definition of a fossil or structure in question as of biological origin such criteria have been established for stromatolites and microfossils this contribution discusses the 6 criteria of biogeneicity of microbially induced sedimentary structures miss those structures are found in sandy deposits of early archean age to the present and rise from the interaction of benthic microbiota with physical sediment dynamics the six criteria for their biogeneicity are i miss occur in rocks of not more than lower greenschist facies ii in stratigraphic sections miss correlate with turning points of regression trangressions iii miss correlate with a characteristic depositional facies that enhances the development and the preservation of microbial mats iv the distribution of miss correlates with the ancient average hydraulic pattern v the geometries and dimensions of fossil miss correspond to that of the modern ones vi the miss include at least one of 9 specific microtextures

early triassic trace fossils from the three gorges area of south china implications for the recovery of benthic ecosystems following the permian triassic extinction abstract the lower triassic daye and jialingjiang formations of the three gorges area south china record the recovery interval of benthic tracemaking invertebrates following the p tr mass extinction a total of 17 ichnospecies in 14 ichnogenera are documented from smithian and spathian strata our trace fossil data in combination with previously published studies show that ichnodiversity in the middle yangtze region increased markedly in the early spathian trace fossils in the smithian are dominated by simple small horizontal burrows including didymaulichnus and planolites whereas spathian trace fossils are diverse and abundant with moderate high bioturbation levels and complex burrow networks such as thalassinoides both burrow sizes and penetration depths increased gradually from the early spathian to the middle late spathian implying a gradual recovery pattern for benthic ecosystems early triassic ichnofossils are characterised by aspects of opportunistic behaviour e g low to moderate ichnodiversity low to moderate bioturbation small burrow widths and shallow tiering suggesting stressed environmental conditions the recovery tempo and pattern of ichnocoenoses in south china is likely structured by temporal and spatial changes of the refuge zone in the early triassic

methane driven oceanic eruptions and mass extinctions focusing on the permian triassic boundary ca 251 ma i explore the possibility that mass extinction can be caused by an extremely fast explosive release of dissolved methane and other dissolved gases such as carbon dioxide and hydrogen sulfide that accumulated in the oceanic water masses prone to stagnation and anoxia e g in silled basins the mechanism of the explosive release is the same as in the lake nyos disaster of 1986 i e a water column eruption caused by the interplay of buoyancy forces and exsolution of dissolved gas the eruption brings to the surface deep anoxic waters that cause extinctions in the marine realm terrestrial extinctions are caused by explosions and conflagrations that follow the massive release of methane the air methane mixture is explosive at methane concentrations between 5 and 15 and by the eruption triggered floods this scenario accounts well for the available data and may be relevant to other phenomena

trace fossils in the aftermath of mass extinction events abstract ichnology has great potential to advance our understanding of mass extinction events and yet is currently an underutilized resource in such studies here we review published ichnological studies for the ordovician silurian permian triassic and cretaceous tertiary extinction recovery intervals in addition new information regarding the triassic jurassic ichnological record from england austria and the western usa is presented trace fossils provide important information on the ecological response of the benthic community at such times in the immediate post extinction aftermath the ichnodiversity burrow size depth of bioturbation and ichnofabric index of the sediments are all much reduced there is an increase in all these parameters through the post extinction recovery period in some cases the stepwise reappearance of certain distinctive ichnotaxa e g diplocraterion rhizocorallium and thalassinoides may be of some stratigraphic use evidence from permian triassic studies indicates that recovery took longer at low tropical palaeolatitudes than mid high palaeolatitudes trace fossils also provide important information on palaeoenvironmental change through the extinction recovery interval the application of ichnology to mass extinction studies is in its infancy but should prove a valuable tool in future research

trace fossils and the aftermath of the permo triassic mass extinction evidence from northern italy abstract the duration of early triassic anoxia in the carbonate ramp settings of the werfen formation dolomites northern italy has been constrained using ichnofabric and sedimentological data this includes fine lamination and abundant pyrite framboids commonly reworked into lags by storm events the anoxic event spanned the entire griesbachian stage and extended from deep waters into extraordinarily shallow water settings evidence for oxygen deficiency can be found in mid and inner ramp facies the extent and duration of this event may at least partially explain the magnitude of the permo triassic mass extinction normal benthic conditions returned rapidly in the dienerian stage and pervasively bioturbated distal ramp facies testify to the ventilation of the deeper water areas of the region in post griesbachian times a post mass extinction radiation is not particularly well displayed in either trace fossil or body fossil diversity compilations from the dolomites moderate low levels of trace fossil diversity are maintained throughout the post griesbachian werfen formation whilst the body fossil data shows a moderate increase from the mid smithian stage there is thus a curious lag period spanning the dienerian to mid smithian when environmental conditions were apparently normal but the marine fauna failed to show any recovery

proliferation of early triassic wrinkle structures implications for environmental stress following the end permian mass extinction lower triassic strata in the western united states and northern italy have yielded the first reported occurrence of microbially mediated wrinkle structures in shallow subtidal siliciclastic paleoenvironments since the cambrian we hypothesize that wrinkle structures formed under reduced infaunalization conditions during the aftermath of the end permian mass extinction these wrinkle structures occur in siliciclastic sedimentary rocks in association with hummocky cross stratification and in some cases trace fossils such as asteriacites rhizocorallium planolites and gyrochorte that indicate a subtidal paleoenvironment wrinkle structures were found in the campil member in the werfen formation of northern italy and in the virgin limestone member of the moenkopi formation and the upper member of the thaynes formation exposed in the western united states the presence of wrinkle structures is likely related to a unique taphonomic window that allowed for the preservation of these delicate features on storm dominated siliciclastic shelves wrinkle structures commonly formed in a variety of subtidal paleoenvironments during the proterozoic cambrian but thereafter became restricted to intertidal supratidal and deep sea environments this restriction has been attributed to the increase in infaunalization of metazoans following the cambrian radiation the proliferation of wrinkle structures in subtidal settings during the early triassic suggests that infaunal bioturbation was reduced after the end permian mass extinction and that this reduction lasted for millions of years

the end permian mass extinction and its aftermath on an equatorial carbonate platform insights from ichnology terra nova 22 195 202 2010 abstract a semi quantitative analysis of the endobenthic activity across the permo triassic boundary ptb was carried out on a 445 m thick well core interval from the persian gulf by logging the degree of bioturbation trace fossil distribution and ichnodiversity id this analysis enables for the first time the evaluation of recovery of endobenthic organisms after the end permian mass extinction by direct comparison of post extinction lower triassic with pre extinction upper permian units the results indicate that the studied shallow marine carbonate platform within an equatorial setting acted as oxygenated refugee for the biotic recovery traces of suspension and deposit feeders reappear simultaneously shortly after the extinction event but are reduced in size macroborings so far unknown from the lower triassic occur where suitable firm or hard substrate was available recovery took place in two phases early induan 50 pre extinction id and 20 30 bioturbation and late induan 75 id and almost 90 bioturbation re established

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

new trace fossil evidence for an early recovery signal in the aftermath of the end permian mass extinction abstract new ichnological data from the lower triassic werfen formation dolomites italy revealed an unexpectedly diverse and complex ichnofauna in mixed siliclastic carbonate shelf sediments of the western tropical tethys shortly after the end permian mass extinction event common elements are thalassinoides palaeophycus and planolites other associated ichnogenera include spongeliomorpha rhizocorallium lockeia catenichnus helminthopsis and taenidium one structure is tentatively determined as curvolithus biostratigraphic data conodonts and bivalves of the trace fossil interval lower seis siusi member suggest a late griesbachian age less than 1 ma after the end permian mass extinction event similarly diverse ichnofossil communities from this time interval have recently been described from the boreal realm but this is the first record of a diverse griesbachian ichnoassemblage from the tropics indicating that the early recovery of trace fossil producers was not latitudinally restricted as previously proposed accordingly relatively advanced recovery stages were reached on a global scale much earlier than the spathian as is commonly acknowledged the early and interregional peak in ichnofaunal recovery implies subsequent ecological setbacks in post griesbachian times that explain the overall delay of benthic recovery until the spathian rather than persistent catastrophic conditions during the griesbachian a global and synchronous succession of crises and relaxation phases after the griesbachian is proposed as an explanatory model for the recovery pattern of benthic ecosystems

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

the permian triassic palynological transition in the guryul ravine section kashmir india implications for tethyan gondwanan correlations this first palynological study of the permian triassic succession in the guryul ravine kashmir india reveals impoverished latest permian spore pollen assemblages in the uppermost zewan formation a rich palynoassemblage from the basal khunamuh formation characteristic of the permian triassic transition zone and depleted triassic assemblages from higher in the khunamuh formation the collective assemblages can be broadly correlated to the densipollenites magnicorpus and klausipollenites decipiens palynozones of peninsular india and to palynofloras spanning the permian triassic boundary elsewhere in gondwana generally low spore pollen yields and poor preservational quality of the studied assemblages hinder more precise correlations and are inferred to be a function of an offshore marine depositional setting on the margin of the neotethys ocean and thermal alteration associated with cenozoic collisional tectonism between india and asia

global correlations of mid early triassic events the induan olenekian boundary in the dolomites italy abstract the dolomites southern alps italy are a reference area for research on the end permian mass extinction and its early triassic aftermath the effects on shallow marine benthic biota are recorded in the werfen formation a thick mixed carbonate siliciclastic sedimentary succession only in its lower griesbachian and upper spathian parts this formation is bio chronologically constrained by means of conodonts and ammonoids whilst no significant bioevent occurs in its middle part this represents an impediment to the biochronologic recognition of the induan olenekian boundary iob the bulla pufels val gardena succession is a key section for the p t boundary and early triassic for global correlation due to the abundance of studies on biostratigraphy mostly on conodonts magnetostratigraphy and chemostratigraphy carried out there by stratigraphers of various nationalities recent chemostratigraphic studies have permitted the recognition of some carbon isotope positive peaks the strongest of which is considered to approximate the iob however various authors have reached different conclusions on the position of the maximum peak and thus on the iob location this leads to important stratigraphic consequences for the calibration of conodont biostratigraphy the critical revision of the traditional stratigraphic units litho and biostratigraphy under evaluated in most of the recent literature and magneto chemo and sequence stratigraphic units allowed herein an integrated stratigraphic scale for the bulla pufels section to be proposed this contribution highlights the mid early triassic dolomites record for regional and global correlations the most significant results attained herein regard the different lithostratigraphic subdivisions of the middle werfen formation and its consequences on the position of the iob with respect to the conodont and bivalve biostratigraphy and sequence stratigraphic units the upper part of the section is attributed herein to the gastropod oolite member which is represented by the lithozone a a predominant supratidal episode and the lower part of the subtidal lithozone b between the lithozones a and b a sequence boundary of 3th order sc2 sc3 is located the maximum carbon isotope excursion is near this boundary which therefore approximates the iob in the dolomites this proposal suggests a dienerian age for the fo of the conodont pachycladina obliqua which occurs about 60 m below the stage boundary no significant biotic event either for molluscs or conodonts occurred across this stage boundary

terrestrial marine teleconnections in the collapse and rebuilding of early triassic marine ecosystems abstract the latest permian mass extinction lpe just prior to the permian triassic boundary at 252 ma resulted in the disappearance of 90 of skeletonized marine taxa and the replacement of the paleozoic fauna by the modern fauna in the immediate aftermath of the extinction shallow marine ecosystems were dominated by microbial communities and diminutive disaster taxa lilliput faunas and the post crisis period in general was characterized by high abundance low diversity marine communities occupying a reduced ecological space the recovery of marine ecosystems was a protracted process lasting throughout the 5 myr long early triassic some clades failed to recover and subsequently went extinct dead clades walking while others recovered only to suffer secondary crises during the early triassic profound environmental changes accompanied these biotic developments deep oceans experienced sustained hypoxia or anoxia for at least several million years following the boundary event anoxia was also widespread in shallow marine areas especially at the time of the lpe but it was more episodic and abated more rapidly than in the deep ocean making it an unlikely factor in the delayed recovery of early triassic marine ecosystems the development of anoxia was due at least in part to a sharp temperature rise following the lpe but may have been stimulated by changes in marine nutrient inventories and productivity rates as well these conditions may have been the result of a concurrent increase in subaerial weathering rates that was sustained into the early triassic in addition to increasing nutrient fluxes to marine areas rapid weathering caused a massive influx of sediment to shallow marine systems subjecting marine biotas to siltation stress this scenario implies close teleconnections between terrestrial and marine environments during the permian triassic boundary crisis with perturbations of the terrestrial realm contributing to the marine crisis

early triassic trace fossils from gondwana interior sea implication for ecosystem recovery following the end permian mass extinction in south high latitude region abstract the kockatea shale formation is one of few marine early triassic successions recorded in the gondwana this formation is exposed at the northampton area of the northern perth basin western australia and was deposited in the gondwana interior sea during the permian and early triassic trace fossils identified within the kockatea shale formation are extremely abundant and contain 16 ichnogenera including a problematic ichnogenus the gondwanan ichnoassemblage is constrained as late smithian in age and is the most diverse among coeval ichnofaunas around the world several types of grazing traces are also reported for the first time in the lower triassic several proxies such as bioturbation level ichnodiversity burrow size trace fossil complexity and tiring level suggest that tracemakers diversified in the gondwana interior sea during the late smithian the gondwanan ichnofauna dominated ecosystem may have reached the ecologic recovery stage 3 of twitchett s model in late smithian the rebound of ichnoassemblages in the aftermath of the end permian mass extinction was not controlled by particular environmental settings all of which however were characterized by oxygenated substrata

evidence for sulfidic deep water during the late permian in the east greenland basin a detailed study of the size distribution of framboidal pyrites in the black shales of the upper permian ravnefjeld formation was performed to evaluate the redox state of the late permian ocean in contrast to framboidal pyrites in bioturbated sediments the smaller and less variable size distribution of pyrite framboids in the laminated shales of the ravnefjeld formation provides persuasive evidence for sulfidic h 2 s rich bottom water conditions in the east greenland basin however the s isotope compositions of both pyrite populations show a similar distribution the widespread 3 4 s values of pyrites 41 2 to 28 2 in the black shales of the ravnefjeld formation indicate a large fractionation up to 52 7 relative to seawater sulfate and may record different pathways of sulfur cycling in sulfidic water columns as well as within sediments the new data from the east greenland basin indicate that environmental stress such as widespread sulfidic conditions could have caused the biotic crisis in the late permian

vegetation changeover across the permian triassic boundary in southwest china extinction survival recovery and palaeoclimate a critical review abstract this paper reviews critically the permian triassic p tr fossil plants and microflora recorded in three well studied terrestrial permian triassic boundary ptb sections namely chahe zhejue and jiucaichong and two marine terrestrial transitional ptb sections namely mide and tucheng in western guizhou province and eastern yunnan province wgey southwest china distinct floral composition abundance and diversity across the ptb allow the establishment of two terrestrial macrofloral assemblages the lobatannularia multifolia gigantoclea guiyangensis l g assemblage was recognized from the upper xuanwei formation while the annalepis peltaspermum a p assemblage from the lower kayitou formation the former flora comprises 105 species in 39 genera and is late changhsingian in age the latter assemblage includes 18 species in 14 genera and is induan in age the changhsingian assemblage is characterized by the loss of many wuchiapingian elements of the gigantopteris flora and an increase of the gymnosperms most of the permian type plant taxa were wiped out in the ptb crisis on land with only few relicts persisting into the early triassic which saw the flourishing of annalepis and common presence of peltaspermum and permian relicts of the gigantopterids during the permian triassic transition some rare gigantopterids elements as well as some peltaspermum representatives survived the biocrisis annalepis a pioneering lycopsid genus in the recovery of the triassic land plants and its proliferation marks the recovery of land plants after the ptb crisis on land in wgey accordingly vegetation changeover across the ptb is marked by a dramatic turnover of plants on land from the permian gigantopteris flora to the triassic annalepis dominated assemblage palynofloras are characterized by a dramatic drop of palynomorphs in both abundance and diversity and show a stepwise extinction pattern moreover macro and microfloras of the wgey region indicate that humid and warm climate regime prevailed through the p tr transition in southwest china the coal forming swamps gradually migrated westward due to marine transgressions throughout the late permian the gigantopteris flora also migrated from east to west and a few species can survive into the earliest triassic in the wgey region but disappeared soon after

adaptive strategies and environmental significance of lingulid brachiopods across the late permian extinction abstract linguliform brachiopods are traditionally considered a conservative group which seems to pass through the late permian extinction without any significant loss and even appear to thrive immediately after the extinction peak in the southern alps lingulids are very common in the post extinction mazzin member early induan of the werfen formation sparse occurrences are also known in the overlying siusi and gastropod oolite members late induan and early olenekian in age respectively the recent discovery of well preserved specimens from a pre extinction bed of the bellerophon formation changhsingian has permitted a detailed comparative analysis mostly based on the interior characters preserved in the lingulid succession from across the extinction beds the following effects on the lingulid populations have been analyzed i change in taxonomic assessment ii adaptive strategies during the surviving and recovery phases and iii environmental proxy connected with the killing mechanisms of the late permian extinction the pre extinction individuals belong to lingularia cf smirnovae biernat and emig a species that is characterized by large sized shells with a short lophophoral cavity the post extinction populations belong to different species and probably even to a different genus the first post extinction population early induan with small sized shells and long lophophoral cavity has been referred to lingularia yini peng and shi it records the most severe effects of the late permian extinction on the marine ecosystems the late induan olenekian lingularia borealis bittner with large sized shells and long lophophoral cavity appears during the first phase of the triassic biotic recovery the main adaptive strategies of lingularia yini in comparison with the permian species include i shell miniaturization ii increasing of the lophophoral cavity surface respiratory surface and iii increasing of shell width length ratio these modifications are interpreted as adaptations towards warming and hypoxia two main killing mechanisms of the marine biota the recovery species lingularia borealis maintains a large lophophoral cavity indicating an adaptation towards predominant low oxygenated bottom marine waters the appearance and the great abundance of lingularia yini in the mazzin member early induan represent a proxy of dysaerobic conditions which determined the appearance of the second phase of the lilliput biota characterized by the definitive disappearance of the rhynchonelliform brachiopods and calcareous algae in the southern alps

the lower triassic of south china abstract the permian triassic boundary of south china has been well known and well studied for decades but what is relatively less noticed is that there are also many excellent marine lower triassic sequences in the region covering various paleogeographic lithofacies this paper presents an outline of the various lower triassic stratigraphic sequences in south china and provides a reference to the application of the lower triassic subdivision and stages the early triassic marine basin of south china is subdivided into five sedimentary provinces cathaysia lower yangtze upper yangtze youjiang and lijiang provinces each province has an interrelated distribution of lithofacies and stratigraphy the lower triassic biostratigraphic sequences of bivalves ammonoids and conodonts are summarized in the various sedimentary facies and provinces of south china the chinese twofold subdivision of the lower triassic is primarily demonstrated as well in this paper

permo triassic boundary superanoxia and stratified superocean records from lost deep sea pelagic cherts of japan and british columbia canada recorded a long term and worldwide deep sea anoxic oxygen depleted event across the permo triassic or paleozoic and mesozoic boundary 251 2 million years ago the symmetry in lithostratigraphy and redox condition of the boundary sections suggest that the superocean panthalassa became totally stratified for nearly 20 million years across the boundary the timing of onset climax and termination of the oceanic stratification correspond to global biotic events including the end guadalupian decline the end permian extinction and mid triassic recovery

a global marine sedimentary response to the end permian mass extinction examples from southern turkey and the western united states the end permian mass extinction greatly diminished marine diversity and brought about a whole scale restructuring of marine ecosystems these ecosystem changes also profoundly affected the sedimentary record data presented here attained through facies analyses of strata deposited during the immediate aftermath of the end permian mass extinction southern turkey and at the close of the early triassic southwestern united states in combination with a literature review show that sedimentary systems were profoundly affected by 1 a reduction in biotic diversity and abundance and 2 long term environmental fluctuations that resulted from the end permian crisis lower triassic strata display widespread microbialite and carbonate seafloor fan development and contain indicators of suppressed infaunal bioturbation such as flat pebble conglomerates and wrinkle structures facies considered unusual in post cambrian subtidal deposits our observations suggest that depositional systems too respond to biotic crises and that certain facies may act as barometers of ecologic and environmental change independent of fossil assemblage analyses close investigation of facies changes during other critical times in earth history may serve as an important tool in interpreting the ecology of metazoans and their environment

loss of the sedimentary mixed layer as a result of the end permian extinction abstract the end permian mass extinction resulted in the most dramatic degradation of marine bottom communities during the phanerozoic one result of this extinction was the long recognized extreme reduction in bioturbation of the early triassic seafloor several lines of evidence i e preferential preservation of epifaunal and very shallow tier infaunal trace fossils paucity of mid and deep tier trace fossils absence of mottled bioturbation textures dominance of cohesive substrates widespread occurrence of microbially induced sedimentary structures in open marine environments ecological composition of early triassic communities show that the reduction in bioturbation was so extreme that the sedimentary mixed layer was eradicated at an interregional scale for the only time since it was established in the early palaeozoic the consequences of this for ecosystem function and geochemical cycling must have been profound and yet they have received little consideration biogenic mixing of sediments is fundamental to geochemical cycling in extant marine ecosystems and it also governs ecologically limiting factors such as nutrient fluxes benthic primary production and availability of ecospace the collapse of biogenic sediment mixing during the early triassic must have affected geochemical properties of sediments and the seawater as reflected in the geologic record of the sulphur cycle additionally many of the proxies traditionally used to infer early triassic seawater anoxia may rather reflect poor sediment oxygenation arising from the extinction of bioturbators because of its impact on seawater and sediment chemistry the loss of the mixed layer may have been an important but hitherto little considered constraint on the recovery from the end permian mass extinction

the paleoenvironmental distribution of phanerozoic wrinkle structures abstract wrinkle structures are microbially induced sedimentary structures that are known to have formed in ancient marine siliciclastic environments this study reviews the sedimentary context and paleoenvironmental distribution of these sedimentary structures throughout three distinct intervals of the phanerozoic the cambrian the post cambrian paleozoic and the lower triassic during these times wrinkle structures are found primarily within two sedimentary environments storm dominated subtidal environments and the intertidal zone subtidal occurrences of wrinkle structures during the post ordovician phanerozoic only appear to occur during intervals of environmental stress while earlier examples from the cambrian and lowermost ordovician likely formed prior to significant increases in extent and depth of bioturbation that hallmark most of the phanerozoic intertidal examples occur regardless of severe environmental stress and may have formed under low levels of bioturbation due to inherent vagaries of a marginal marine setting these environmental preferences appear to be conservative throughout the phanerozoic and may very well extend throughout earth s history

patterns of bivalve biodiversity from early to middle triassic in the southern alps italy regional vs global events abstract the triassic records the severe effects of the end permian mass extinction and the beginning of the mesozoic modern adaptive radiation of marine invertebrates as far as bivalves are concerned a group which was relatively unaffected by the extinction diversification started in the middle triassic more particularly during the anisian thus the interval between the basal triassic induan and anisian is crucial in analysing the biodiversity changes and diversification patterns of these molluscs this analysis is discussed at genus level and based on the regional records of the southern alps biodiversity changes are examined in connection with palaeogeographic evolution the conquest of vacated ecologic niches and climatic changes the lowest point of generic richness as an immediate aftermath of the p t mass extinction is recorded in the induan units mazzin and siusi mbs of the werfen formation which include only five genera numerically dominated by claraia and unionites twelve genera are represented in the olenekian campil val badia and cencenighe members such an increasing richness is mostly connected with the recovery of pectinids and endobyssate bakevellids typical marine biota such as ammonoids tirolites and dinarites fauna and crinoids also appear in this time the richness and structure of the early anisian bithynian bivalve assemblages contained in the gracilis formation and equivalent units of southern alps do not significantly change 15 genera in comparison with those from olenekian the most relevant increase in bivalve genera 31 genera occurs in the late anisian mostly in the pelsonian calcare di recoaro and equivalent units when a strong tectonic phase considerably differentiated the marine habitats and ecological niches in the southern alps however bivalve pelsonian radiation is recorded in other tethyan and peri tethyan areas and coincides with the reappearance of marine stenotopic hard bottom dwellers and reef communities including scleractinian corals therefore it represents a global bioevent which indicates the fully recovery of the physical and chemical limiting factors of the sea water in the southern alps the diversification of bivalves after the end permian extinction occurred in two steps at the end of smithian early olenekian when their recovery began and in the pelsonian late anisian when their radiation parallels with the recovery of hard bottom communities and metazoan reefs both the events occurred at the end of humid phases

aftermath of the permian triassic mass extinction event paleoecology of lower triassic carbonates in the western usa paleoecologic study of invertebrate faunas from three successive early triassic seaways reveals that biotic recovery from the end permian mass extinction event was slow and that full recovery did not occur until after the early triassic simple cosmopolitan opportunistic generalists and low diversity low complexity paleocommunities were characteristic of the entire early triassic in the western usa an increase in guild and taxonomic diversity was observed with the addition of several new higher taxa in the late early triassic spathian to the almost exclusively molluscan faunas of the earlier early triassic nammalian potential disaster forms the inarticulate brachiopod lingula and the paper pecten claraia dominated the earliest early triassic faunas griesbachian and even occurred in the late early triassic normal marine stromatolites comparison with data on faunas from the permian and triassic suggests that even the most diverse early triassic faunas in the spathian were rather low in guild diversity and species richness these characteristics of genera and paleocommunities in the early triassic may be typical of mass extinction aftermaths

microbial shaping of sedimentary wrinkle structures wrinkle structures in ancient sedimentary environments are enigmatic wave tank experiments suggest that wrinkle structures are shaped by microbial mat fragments that are moved by waves over sandy bed surfaces and thus are morphological biosignatures

lower triassic large sea floor carbonate cements their origin and a mechanism for the prolonged biotic recovery from the end permian mass extinction precipitation of inorganic calcium carbonate is a common occurrence in both modern and ancient marine environments however synsedimentary growth of large 5 10 cm crystalline carbonate cements directly onto the sea floor has been thought to be limited to the proterozoic when seawaters were highly oversaturated with calcium carbonate compared to average phanerozoic values outer shelf to slope deposits of the lower triassic union wash formation in east central california deposited in oxygen restricted settings contain crystalline calcium carbonate cements that appear to have grown directly on the sea floor paleoenvironmental analyses indicate that these large calcium carbonate cements grew under conditions that were similar to those proposed for the precipitation of inorganic calcite in the black sea sulfate reduction of organic matter led to an increase in the amount of bicarbonate ion in deep waters and a concomitant increase in co 2 and alkalinity mixing with surface waters led to co 2 degassing and precipitation of cements from waters supersaturated with calcium carbonate the presence of these cements and associated facies thus provides evidence of harsh environmental conditions in the early triassic at the regional level which may have acted in concert with biotic effects of the end permian mass extinction as well as similar deleterious conditions e g shelf anoxia in other regions to produce a prolonged as well as temporally and geographically variable biotic recovery from this mass extinction