timing of recovery from the end permian extinction geochronologic and biostratigraphic constraints from south china four volcanic ash beds bracket the early middle triassic boundary as defined by conodont biostratigraphy in a stratigraphic section in south china high precision u pb dates of single zircons allow us to place the early to middle triassic olenekian anisian boundary at 247 2 ma magnetic reversal stratigraphy allows global correlation the new dates constrain the early triassic interval characterized by delayed biotic recovery and carbon cycle instability to 5 m y this time constraint must be considered in any model for the end permian extinction and subsequent recovery

δ13c evidence that high primary productivity delayed recovery from end permian mass extinction euxinia was widespread during and after the end permian mass extinction and is commonly cited as an explanation for delayed biotic recovery during early triassic time this anoxic sulfidic episode has been ascribed to both low and high productivity states in the marine water column leaving the causes of euxinia and the mechanisms underlying delayed recovery poorly understood here we use isotopic analysis to examine the changing chemical structure of the water column through the recovery interval and thereby better constrain paleoproductivity the 13c of limestones from 5 stratigraphic sections in south china displays a negative gradient of approximately 4 from shallow to deep water facies within the lower triassic this intense gradient declines within spathian and lowermost middle triassic strata coincident with accelerated biotic recovery and carbon cycle stabilization model simulations show that high nutrient levels and a vigorous biological pump are required to sustain such a large gradient in 13c indicating that early triassic ocean anoxia and delayed recovery of benthic animal ecosystems resulted from too much productivity rather than too little

early triassic seawater sulfate drawdown abstract the marine sulfur cycle is intimately linked to global carbon fluxes atmospheric composition and climate yet relatively little is known about how it responded to the end permian biocrisis the largest mass extinction of the phanerozoic here we analyze carbonate associated sulfate cas from three permo triassic sections in south china in order to document the behavior of the c s cycle and its relationship to marine environmental changes during the mass extinction and its aftermath we find that 34 s cas varied from 9 to 44 at rates up to 100 myr 1 during the griesbachian smithian substages of the early triassic we model the marine sulfur cycle to demonstrate that such rapid variation required drawdown of seawater sulfate concentrations to 4 mm and a reduction in its residence time to 200 kyr this shorter residence time resulted in positive covariation with 13 c carb due to strong coupling of the organic carbon and pyrite burial fluxes carbon and sulfur isotopic shifts were associated with contemporaneous changes in climate marine productivity and microbial sulfate reduction rates with negative shifts in 13 c carb and 34 s cas linked to warming decreased productivity and reduced sulfate reduction sustained cooling during the spathian re invigorated oceanic overturning circulation reduced marine anoxia and limited pyrite burial as seawater sulfate built to higher concentrations during the spathian the coupling of the marine c and s cycles came to an end and a general amelioration of marine environmental conditions set the stage for a recovery of invertebrate faunas variation in seawater sulfate during the early triassic was probably controlled by climate change possibly linked to major eruptive phases of the siberian traps

size variation of conodonts during the smithian spathian early triassic global warming event the early triassic smithian spathian boundary ssb crisis coincided with an episode of extreme warmth a high resolution stratigraphic framework comprising six conodont zones is provided in the jiarong section nanpanjiang basin in south china detailed size measurements of 441 conodont elements of the closely related genera neospathodus triassospathodus and novispathodus show for the first time that this clade suffered a temporary but significant size reduction during the ssb crisis the size reduction of conodonts was probably caused by an episode of global warming

carbon isotope record of the p t boundary and the lower triassic in the southern alps evidence for rapid changes in storage of organic carbon abstract the carbonate carbon isotope record of lower triassic shelf sediments was investigated in the pufels and l om picol uomo sections of the western central dolomites to derive a complete record from the permian triassic transition to the uppermost lower triassic from the western tethys the carbon isotope record shows the well studied decrease at the permian triassic boundary ptb followed by an increase to about 1 5 at the dienerian smithian boundary the 13c values increase to a pronounced 6 maximum a steady rapid drop until the upper smithian below 2 follows this 13c peak at the smithian spathian transition a steep rise to positive values is documented the positive carbon isotope peak is interpreted to reflect an interval of enhanced burial of organic carbon whereas the isotopic minima provide evidence of periods of oxidation of organic matter and or release of isotopically light carbon this may be ascribed to quickly changing environmental conditions which have already been postulated by paleontologists due to the delayed biotic recovery from the permian triassic extinction event because of the short time interval these positive isotope excursions represent their generation by burial of organic carbon in periods of high productivity and or anoxia appears plausible concurrent carbon isotopic excursions are reported from iran pakistan and oman as well as from southern china which indicate an at least tethys wide event if the excursion proves to be of global significance dark shale deposited in the pelagic panthalassa ocean may have acted as sink for organic carbon supporting the hypothesis of a periodically stratified ocean in the lower triassic

transient metazoan reefs in the aftermath of the end permian mass extinction microbes were thought to be the dominant reef constructors following the end permian mass extinction sponge microbe reef deposits formed in the early triassic from the western united states suggest that instead metazoan reef building continued immediately following the extinction wherever marine conditions allowed

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

identifying the causes of sea level change global mean sea level change has increased from a few centimetres per century over recent millennia to a few tens of centimetres per century in recent decades a review of the latest work shows that global mean sea level rise is unlikely to exceed one metre over the twenty first century but regional departures from this global mean could reach several decimetres

timing of the early triassic carbon cycle perturbations inferred from new u pb ages and ammonoid biochronozones based on analyses of single thermally annealed and chemically abraded zircons a new high precision u pb age of 251 22 0 20 ma is established for a volcanic ash layer within the kashmirites densistriatus beds of early smithian age early triassic from the luolou formation northwestern guangxi south china this new date together with recalculated uncertainties of previous u pb ages from the same section m ovtcharova h bucher u schaltegger t galfetti a brayard j guex new early to middle triassic u pb ages from south china calibration with ammonoid biochronozones and implications for the timing of the triassic biotic recovery earth planet sci lett 243 2006 463 475 allows constraining the time framework of the early triassic and leads to an estimated duration of i ca 0 7 0 6 my for the smithian and ii a maximal duration of ca 1 4 0 4 my for the griesbachian dienerian time interval the new u pb age considerably reduces the absolute age gap comprised between the permian triassic boundary and the spathian late early triassic the new age framework provides the basis for the calibration of a new carbonate carbon isotope and ammonoid records of the early triassic luolou fm which in turn are of high significance for global correlations and for carbon cycle modeling this calibration indicates that the most significant and fastest early triassic carbon isotope perturbations occur between the earliest smithian and the early spathian thus spanning a time interval of about 1 my whatever caused these carbon cycle shifts of high intensity and short duration there is evidence for connections between these fluctuations the pulsate recovery of ammonoids and conodonts as well as climate changes

lower triassic sulphur isotope curve of marine sulphates from the dolomites n italy abstract 6 evaporite samples from the latest permian to the late lower triassic have been sampled at marine carbonate sections in the southern alps the sulphur isotope ratio of the sulphate has been determined to learn about the changes of the marine 34s ratio during the investigated period as it is known from the literature that a profound change from depleted to heavily enriched 34s values occurred within the lower triassic the carbonates from the same sections have been analysed for their carbon isotope pattern as the carbon isotope curve of the lower triassic has a very distinct pattern it enables the stratigraphic location of the evaporite layers in the section thus it can be shown that the change in 34s already occurred at the dienerian smithian boundary or within the dienerian stratification and re mixing of ocean water are the most plausible interpretations for the observed isotope patterns

evidence for recurrent changes in lower triassic oceanic circulation of the tethys the δ13c record from marine sections in iran abstract stable carbon isotope curves derived from lower triassic carbonate rocks from three iranian sections are established to investigate changes in the carbon cycle during the early triassic in this area the sections are located in the south center abadeh north amol and northwest zal of iran all three curves show a similar pattern starting out with high 13 c values in the uppermost permian decreasing across the permian triassic boundary an increase toward more positive values during the griesbachian that slowly increase further up during the dienerian followed by a positive excursion to values as high as 8 near the dienerian smithian boundary during the smithian values return to below 0 whereas second positive excursion to values higher than 3 is recorded at the smithian spathian boundary again followed by a drop in 13 c into the spathian and a final excursion to positive values at the spathian anisian boundary the results from these iranian sections are consistent with previous studies from italy and china thus strongly suggesting that the recorded 13 c variability represents at least tethys wide geochemical signals moreover the new curves reveal evidence of high amplitude frequent oscillations pointing toward rapid and profound changes in the global carbon cycle during the lower triassic stratification of the ocean interrupted by episodic overturning transporting deep water to the ocean surface is a viable mechanism to account for the recorded isotope variations provided that the 13 c curve is representative of the global lower triassic ocean it has high potential for accurately dating sedimentary successions via chemostratigraphy

sea level rise due to polar ice sheet mass loss during past warm periods background although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level gmsl rise over the last century mass loss from the greenland and antarctic ice sheets is expected to exceed other contributions to gmsl rise under future warming to better constrain polarice sheetresponse to warmer temperatures we draw on evidence from in terglacial periods in the geologic record that ex perienced warmer polar temperatures and higher gmsls than present coastal records of sea level from these previous warm periods dem onstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales inferring gmsl and ice volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models advances interdisciplinary studies of geo logic archives have ushered in a new era of deciphering magnitudes rates and sources of sea level rise advances in our understanding of polar ice sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea level reconstructions better ice sheet constraints and the recognition that several geophysical processes cause spatially complex patterns in sea level in particular accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea level records and has reconciled a number of site specific sea level reconstructions for warm periods that have oc curred within the past several hundred thou sand years this enables us to infer that during recent interglacial periods small increases in

the early triassic ammonoid recovery paleoclimatic significance of diversity gradients ammonoids recovered much faster than other marine shelly invertebrates after the end permian mass extinction based on a refined global data set at the basin level we investigate the paleobiogeographical global latitudinal and longitudinal diversity patterns in terms of climatic changes during the early triassic such analysis differs from already published qualitative or quantitative studies in that it estimates faunal patterns and endemicity at an ecologically meaningful level of spatial resolution i e at the basin level during the early triassic the global first order trend in increasing ammonoid diversity was accompanied by a progressive change from cosmopolitan to latitudinally restricted distributions this led to the emergence of a clear latitudinal diversity gradient during most of the smithian and spathian stages which entails increased steepness of the sea surface temperature gradient during the late early triassic however two brief episodes of ammonoid cosmopolitanism combined with low global diversity interrupted the first order increasing trend at the very beginning of the smithian and at its very end the longitudinal analysis of smithian distributions indicates a westward decrease of diversity within the tethys which faded away during the spathian analysis of endemicity indicates a rapid biogeographical maturing and structuring of faunas concomitant with the edification of the latitudinal diversity gradient

late early triassic climate change insights from carbonate carbon isotopes sedimentary evolution and ammonoid paleobiogeography the late early triassic sedimentary facies evolution and carbonate carbon isotopemarine record 13ccarb of ammonoid rich outer platform settings show striking similarities between the south china block scb and the widely distantnorthern indianmargin nim the studied sections are located within the triassic tethyshimalayan belt losar section himachal pradesh india and the nanpanjiang basin in the south china block jinya section guangxi province respectively carbon isotopes from the studied sections confirm the previously observed carbon cycle perturbations at a time of major paleoceanographic changes in the wake of the end permian biotic crisis this study documents the coincidence between a sharp increase in the carbon isotope composition and the worldwide ammonoid evolutionary turnover extinction followed by a radiation occurring around the smithian spathian boundary based on recent modeling studies on ammonoid paleobiogeography and taxonomic diversity we demonstrate that the late early triassic smithian and spathian was a time of a major climate change more precisely the end smithian climate can be characterized by a warm and equable climate underlined by a flat pole to equator sea surface temperature sst gradient while the steep spathian sst gradient suggests latitudinally differentiated climatic conditions moreover sedimentary evidence suggests a transition froma humid and hot climate during the smithian to a dryer climate fromthe spathian onwards by analogywith comparable carbon isotope perturbations in the latedevonian jurassic andcretaceouswe propose that high atmosphericco2 levels could have been responsible for the observed carbon cycle disturbance at the smithian spathian boundary we suggest that the end smithian ammonoid extinction has been essentially caused by a warm and equable climate related to an increased co2 flux possibly originating froma short eruptive event of the siberian igneous province this increase in atmospheric co2 concentrations could have additionally reduced the marine calcium carbonate oversaturation and weakened the calcification potential of marine organisms including ammonoids in late smithian oceans

permian triassic boundary interval in the middle east iran and n oman progressive environmental change from detailed carbonate carbon isotope marine curve and sedimentary evolution abstract the end permian negative 13c excursion is well known but its cause and chronology are still in question in an attempt to decipher the timing and reasons for this strong decrease we established high resolution sedimentological biostratigraphical and carbonate carbon isotopic studies in four sections in iran abadeh shareeza zal and djulfa and two in oman wadi sahtan the position of the sections on two different margins of the neotethys has allowed us to distinguish between local and global signals this high resolution chemostratigraphy tested for isochrony on the basis of an updated high resolution conodont and ammonoid biostratigraphy allows the discrimination of nine successive isotopic events ie 0 8 for the permian triassic boundary interval ptbi the negative excursion of the ptbi has been separated into four distinct parts a first drop ie 0 occurs in the late wuchiapingian with an amplitude of around 1 3 a second decrease begins ie 1 2 at the base of the dzhulfites ammonoid beds changhsingian and continues gradually until the extinction event top jolfensis conodont interval without important second order variations its amplitude varies between 1 5 and 2 8 and its duration has been estimated around 2 2 ma revealing a non catastrophic phenomenon the lower meishanensis praeparvus conodont zone records stationary to slightly increasing values ie 3 the interval of the curve after the extinction event between the upper meishanensis praeparvus zone and the base of the i isarcica zone records numerous second order variations ie 4 7 its amplitude is of 1 2 3 1 these second order variations are correlatable in iran but with some uncertainty with oman poor correlation of these small peaks with others published sections might be due to a higher sensitivity to local perturbations and a lower buffer capacity of the whole ocean we assume that the processes leading to the extinction event also caused the isotopic decrease before the extinction level with a maximal amplitude of only 2 8 this allows consideration of some possible mechanisms that were rejected as unrealistic to cause a 4 6 excursion

conodont diversity and evolution through the latest permian and early triassic upheavals abstract a study of latest permian and early triassic multielement conodonts identifies eight steps in their evolutionary history during an interval when earth s biosphere was highly stressed these steps are 1 gradual decline of families and genera through the changhsingian up to the late griesbachian 2 conodont biofacies change and extinction of tethyan endemic species close to the permian triassic boundary ptb 3 faunal turnover with extinction and origination in the late griesbachian 4 initial radiation in gondolellids and diversification in apparatuses during the dienerian 5 explosive radiation in the early middle smithian 6 major extinction in the late smithian 7 major radiation early in the spathian 8 gradual turnover and decline in the late spathian through early anisian conodontophorids were reduced from five families at the beginning of the changhsingian to three by the ptb and to two late in the griesbachian from the changhsingian to the late griesbachian there was a single multielement apparatus represented in the gondolellidae whereas by the olenekian there were at least twelve given absolute age constraints the conodont recovery in the aftermath of the ptb was extraordinary conodont evolution during the dienerian remains obscure but was very significant in terms of changes in multielement apparatuses in spite of induan extinctions generic diversity generally increased from the ptb up to the late smithian in terms of species genera and multielement apparatuses the acme of triassic conodonts was in the middle smithian and the biggest extinction was in the late smithian after this extinction generic and apparatus diversity quickly returned to high levels marking a significant spathian recovery gradual decline characterized the late spathian and persisted into the early anisian a synthetic summary of the temporal distribution and proposed relationships amongst all known lower triassic conodonts provide an improved foundation for biostratigraphic and biochronologic studies extinction and radiation trends correlate well with sea level changes and sequence boundaries faunal turnovers correspond to lowstands in the late griesbachian late smithian and late spathian and radiations correspond to transgressions in the early griesbachian early smithian and early spathian the trends also correlate with perturbations in the carbon cycle with lower triassic 13c minima corresponding to extinction and faunal turnover and positive values generally occurring during radiations however middle triassic recovery of marine benthos follows a positive maxima and an overall decline in conodont diversity new taxa borinella chowadensis b megacuspa neogondolella griesbachensis and n mongeri are described

the smithian spathian boundary late early triassic a review of ammonoid conodont and carbon isotopic criteria abstract the transition from the smithian substage to the spathian substage of the olenekian stage of the late early triassic was a critical time marked by a series of biological and environmental changes during the multimillion year recovery interval following the end permian mass extinction however the smithian spathian boundary ssb does not yet have an agreed definition a shortcoming that complicates high resolution analysis of events during the smithian spathian transition here we review key biostratigraphic i e ammonoid and conodont studies of the smithian and spathian substages in historically important regions e g the canadian arctic for the boreal realm western north america for the eastern panthalassic ocean and more recently re studied locations e g pakistan and india in the southern tethys south china in the eastern tethys as well as the carbon isotope chemostratigraphy of 29 major smithian spathian sections globally key ammonoid genera e g wasatchites anasibirites glyptophiceras and xenoceltites of the late smithian and bajarunia tirolites and columbites of the early spathian conodont species e g scythogondolella milleri novispathodus waageni and borinella buurensis of the late smithian and triassospathodus hungaricus neogondolella aff sweeti and icriospathodus spp of the early spathian and carbonate carbon isotope excursions provide appropriate markers for constraining the ssb use of the first occurrence of the conodont novispathodus pingdingshanensis as a potential marker of the ssb is also discussed based on correlations of biostratigraphic and carbon isotope data globally we propose to revise previous placements of the ssb transition in some sections finally we show that the smithian thermal maximum stm herein named was middle smithian in age and not correlative with the ssb as inferred in some earlier studies and that the ssb coincided with a subsequent major global cooling event

response to comment on lethally hot temperatures during the early triassic greenhouse goudemand et al replot a subset of our well constrained data using a new early triassic biostratigraphic scheme based on a lower resolution ammonoid zonation scheme and hypothetical ammonoid conodont correlation to produce a less distinct seawater temperature history we dispute their unsubstantiated correlation and consequently their allegations

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

the intensity of chemical weathering geochemical constraints from marine detrital sediments of triassic age in south china abstract a geochemical study of major trace elements in detrital sediment and carbon oxygen isotopes in carbonate was carried out for a marine stratigraphic profile of early triassic that is composed of argillaceous limestone and calcareous mudstone in the lower yangtze basin south china the results place constraints on the geochemical behaviors of various elements in the detrital sediment that was deposited in the residual paleotethyan seawater this leads to establishment of new geochemical proxies for chemical weathering of continental crust in terms of the correlations between element concentrations and their variations in the profile the elements are categorized into four groups with respect to the difference in their geochemical behaviors the first group is composed of al th sc be in ga k rb and cs that are tightly correlated due to their immobility during chemical weathering the second group is composed of ca and na that show opposite variation trends with th and sc on account of their mobile behavior in the weathering profile the third group is composed of high field strength elements such as ti nb ta zr and hf that are closely correlated with each other because they were primarily taken up by heavy minerals from sedimentary provenance the fourth group is composed of redox sensitive elements such as co cu fe mn and ni that are correlated with s and thus mainly hosted by sulfides th sc ca and na were not amenable to changes in sedimentary provenance and thus are selected to establish the new proxies for chemical weathering these are composed of logarithmic parameters such as log th ca log sc ca log th na 5 ca and log sc na 5 ca they exhibit synchronous increases at the permian triassic boundary the middle griesbachian and the early smithian indicating the enhancements of chemical weathering high proxy values approaching the values for the extremely weathered product of granodiorite occurred in the middle to late griesbachian and early smithian demonstrating the occurrences of extreme chemical weathering and very warm paleoclimate in those periods these paleoclimatic changes are concordant with results from geochemical studies elsewhere in the world therefore the intensity of chemical weathering can be indicated by the new geochemical proxies for the different properties of elements in marine detrital sediments

smithian and spathian early triassic ammonoid assemblages from terranes paleoceanographic and paleogeographic implications early triassic paleobiogeography is characterised by the stable supercontinental assembly of pangea however at that time several terranes such as the south kitakami massif sk south primorye sp and chulitna respectively and presently located in japan eastern russia and alaska straddled the vast oceans surrounding pangea by means of quantitative biogeographical methods including cluster analysis non metric multidimensional scaling and bootstrapped spanning network applied to smithian and spathian early triassic ammonoid assemblages we analyze similarity relationships between faunas and suggest paleopositions for the above cited terranes taxonomic similarities between faunas indicate that primary drivers of the ammonoid distribution were sea surface temperature and currents possible connections due to current controlled faunal exchanges between both sides of the panthalassa are shown and terranes such as sk sp and chulitna played an important role as stepping stones in the dispersal of ammonoids sk and sp terranes show strong sub equatorial affinities during the smithian thus suggesting a location close to south china at the same time the chulitna terrane shows strong affinities with equatorial faunas of the eastern panthalassa this paleoceanographic pattern was markedly altered during the spathian possibly indicating significant modifications of oceanic circulation at that time as illustrated by the development of a marked intertropical faunal belt across tethys and panthalassa

comment on lethally hot temperatures during the early triassic greenhouse sun et al reports 19 october 2012 p 366 reconstructed permian to middle triassic equatorial seawater temperatures after correct temporal positioning of their data points their presumed trends of temperature changes and hence their assumption of a one to one relationship between putative lethally hot seawater temperatures and a disputable equatorial eclipse of some organisms are no longer supported by their data

new early triassic ammonoid faunas from the dienerian smithian boundary beds at the induan olenekian gssp candidate at mud spiti northern india new collections at the induan olenekian boundary gssp candidate at mud himachal pradesh northern india lead to the recognition of several well preserved ammonoid faunas that significantly improve the biostratigraphic resolution in the beds underlying the proposed gssp level in ascending order the new biostratigraphical sequence comprises the ambites lilangense beds the fuchsites markhami beds the kingites lens beds the prionolobus rotundatus beds the flemingites bhargavai beds the kashmiritidae gen nov a beds and the vercherites cf pulchrum beds the faunas from bed 10 located about 1 m below the proposed gssp level contain certain ammonoids with typical early smithian affinity flemingitidae kashmiritidae and thus reflect the beginning of the early smithian evolutionary radiation seen from an evolutionary point of view the dienerian smithian boundary can therefore be placed just below bed 10 ideally the stage boundary should also be intercalibrated with other biological chemical or physical proxies as additional tools for world wide correlations four new species flemingites bhargavai kingites korni kingites parkashi and xenodiscoides variocostatus and two new genera mudiceras vercherites are described

lower triassic conodont sequence in chaohu anhui province china and its global correlation abstract the early triassic paleogeographical setting of the chaohu section in china was in a deep part of the yangtze platform and this has resulted in a rather complete lower triassic sequence with rich ammonoid and conodont successions three lower triassic sections west pingdingshan north pingdingshan and south majiashan have been sampled in detail for a systematic conodont study eight conodont zones are recognized in ascending order these are the zones of hindeodus typicalis neogondolella krystyni neospathodus kummeli neospathodus dieneri neospathodus waageni neospathodus pingdingshanensis neospathodus homeri and neospathodus anhuinensis these are correlated with the sequences in north america and other areas of the world the succession provides a good basis for the definition of the global stratotype of the induan olenekian boundary gssp which has been proposed at the base of the neospathodus waageni zone in west pingdingshan seven new species are introduced neospathodus chaohuensis n chii n concavus n eotriangularis n pingdingshanensis n posterolongatus n tongi a new subspecies n waageni eowaageni and three morphotypes of n dieneri

isotopic evidence for an anomalously low oceanic sulfate concentration following end permian mass extinction abstract the cataclysmic end permian mass extinction was immediately followed by a global expansion of microbial ecosystems as demonstrated by widespread microbialite sequences disaster facies in shallow water settings here we present high resolution carbonate carbon 13 c carb and carbonate associated sulfate sulfur isotope 34 s cas records from the microbialite in the cili permian triassic p tr section in south china a stepwise decline in 13 c carb begins in the underlying skeletal limestone predating the main oceanic mass extinction and the first appearance of microbialite and reaches its nadir in the upper part of the microbialite layer the corresponding 34 s cas in the range of 17 4 to 27 4 is relatively stable in the underlying skeletal limestone and increases gradually from 2 m below the microbialite rising to a peak at the base of the microbialite two episodes of positive and negative shifts occurred within the microbialite layer and exhibit a remarkable co variance of sulfur and carbon isotope composition the large amplitude of the variation in 34 s cas as high as 7 per 100 kiloyears suggests a small oceanic sulfate reservoir size at this time furthermore the 13 c carb and 34 s cas records co vary without phase lag throughout the microbialite interval implying a marine driven c cycle in an anoxic ocean with anomalously low oceanic sulfate concentrations on the basis of a non steady state box model we argue that the oceanic sulfate concentration may have fallen to less than 15 perhaps as low as 3 of that in the modern oceans low oceanic sulfate concentration likely was the consequence of evaporite deposition and widespread anoxic sulfidic conditions prior to the main mass extinction by promoting methanogenesis and a build up of atmospheric ch 4 and co 2 low oceanic sulfate may have intensified global warming exacerbating the inimical environmental conditions of the latest permian

the lower triassic sulphur mountain formation in the wapiti lake area lithostratigraphy conodont biostratigraphy and a new biozonation for the lower olenekian smithian earth science sector ess contribution 20080714 the sulphur mountain formation in the wapiti area is subdivided into the phroso meosin mountain new and vega members which collectively span much of the lower triassic the smithian conodont faunas are particularly well developed and form the basis of three partly new conodont zones and two new subzones the lachrymiformis zone meeki zone and mosheri zone with the last subdivided into the phryna and milleri subzones an informal lowermost smithian nepalensis interval is introduced although it has yet to be found in the area the phroso member is latest griesbachian dienerian and in its uppermost part smithian specifically the lachrymiformis and meeki zones these are shown to be equivalent to the euflemingites romunduri ammonoid zone the meosin mountain member is assigned to the meeki zone in its lower part and the phryna subzone of the mosheri zone in its upper part at least the upper part of the mosheri zone is equivalent to the anawasatchites tardus ammonoid zone the mackenzie dolomit

the lower triassic sedimentary and carbon isotope records from tulong south tibet and their significance for tethyan palaeoceanography abstract the lower triassic sedimentary and carbonate organic carbon isotope records from the tulong area south tibet are documented in their integrality for the first time new age control is provided by ammonoid and conodont biostratigraphy the basal triassic series consists of griesbachian dolomitic limestones similar to the kathwai member in the salt range pakistan and to the otoceras beds in spiti india the overlying thin bedded limestones of dienerian age strongly resemble the lower ceratite limestone of the salt range they are followed by a thick series of dark green silty shales of dienerian early smithian age without fauna that strikingly resemble the ceratite marls of the salt range this interval is overlain by thin bedded light grey fossil rich limestones of middle to late smithian age resembling the upper ceratite limestone of the salt range these are followed by a shale interval of early spathian age that has no direct counterpart in other tethyan sections carbonate production resumes during the late early and middle spathian with the deposition of red bioclastic nodular limestone ammonitico rosso type facies apart from its colour this facies is similar to the one of the niti limestone in spiti and of the spathian nodular limestone in guangxi south china as in other tethyan localities such as spiti the early middle anisian part of the tulong section is strongly condensed and is characterized by grey thin bedded limestones with phosphatized ammonoids as for many other tethyan localities the carbon isotope record from tulong is characterized by a late griesbachian dienerian positive 13ccarb excursion 2 and a very prominent positive excursion 5 at the smithian spathian boundary thus confirming the well documented perturbations of the global carbon cycle following the permian triassic mass extinction event

evolution of oceanic redox conditions during the permo triassic transition evidence from deepwater radiolarian facies abstract the 90 biodiversity loss among marine invertebrate species during the end permian mass extinction the most severe phanerozoic biocrisis has been attributed to widespread oceanic anoxia superanoxia recent studies of the lithofacies inorganic geochemistry and biomarkers of permian triassic boundary ptb sections have yielded an inferred pattern of oceanic redox changes that is complex and sometimes inconsistent in this contribution we review the ecology of radiolarians an important microzooplankton group during the permo triassic transition and consider its implications for contemporaneous changes in paleoceanographic conditions our analysis shows that 1 late permian radiolarian faunas were cosmopolitan with different orders having specific depth preferences i e albaillellarians favoring deeper waters and spherical forms entactinarians and spumellarians shallower waters 2 deep water taxa declined earlier than shallow water taxa 3 many paleozoic type taxa survived into the early triassic but went extinct during a second crisis in the dienerian dead clade walking followed by the appearance or expansion of mesozoic type taxa during the olenekian and 4 the survival of paleozoic type taxa during the early triassic was greater at higher paleolatitudes than in the tropics these observations are consistent with a first order redox control on radiolarian faunal distributions specifically a shallowing and poleward expansion of the oceanic oxygen minimum zone during the ptb crisis the consequent adaptation of some deepwater taxa to shallower environments resulted in early triassic radiolarian faunas in continental basins becoming more similar to those in pelagic settings enhanced survival of paleozoic type taxa in high latitude regions indicates that the main stressor on permo triassic radiolarian communities was reduced oceanic oxygen levels stronger in the tropics rather than climatic warming stronger at the poles

climatic and biotic upheavals following the end permian mass extinction the recovery from the end permian mass extinction was slow and prolonged a temperature reconstruction shows that further biotic crises during the recovery were associated with extreme warmth

reconstruction of early triassic ocean redox conditions based on framboidal pyrite from the nanpanjiang basin south china abstract widespread oceanic anoxia has been implicated as an important factor in the ptb permian triassic boundary mass extinction and the delayed recovery of early triassic marine ecosystems an investigation of framboidal pyrite in the bianyang section nanpanjiang basin south china suggests that euxinia dysoxia peaked during the induan late smithian to earliest spathian and late spathian these anoxic episodes show a relationship albeit imperfect to major episodes of climatic warming during the early triassic that were associated with intensified oceanic stratification reduced marine productivity and organic carbon sinking fluxes as well as diminished burial fluxes of organic carbon and reduced sulfur in contrast intervals of better oxygenated marine conditions were associated with episodes of relative climatic cooling during the early to middle smithian and mid spathian the degree of ventilation of the thermocline region in particular had a profound effect on marine biotas with intervals of improved ventilation resulting in increased global diversity among ammonoids and conodonts and increased local abundance of foraminifera in the nanpanjiang basin these observations suggest that oceanic redox fluctuations played an important role in the delayed recovery of early triassic marine ecosystems and specifically that episodic expansion of oceanic oxygen minimum zones omzs resulted in repeated setbacks to the recovery process a pattern that persisted until the late spathian

smithian spathian boundary event evidence for global climatic change in the wake of the end permian biotic crisis one of the most important carbon cycle perturbations following the end permian mass extinction event straddles the smithian spathian boundary ssb olenekian early triassic this anomaly is characterized by a prominent positive carbon isotope excursion known from tethyan marine rocks its global signifi cance is established here by a new high paleolatitude record spitsbergen paleontological evidence such as boreal palynological data barents sea norway and global patterns of ammonoid distribution indicates a synchronous major change in terrestrial and marine ecosystems near the ssb the reestablishment of highly diverse plant ecosystems including the rise of woody gymnosperms and decline of the formerly dominating lycopods is interpreted as an effect of a major climate change this hypothesis is supported by modeling of ammonoid paleobiogeography the distribution patterns of which are interpreted as a proxy for sea surface temperatures sst the latest smithian thus appears to have been a time of a warm and equable climate as expressed by an almost fl at pole to equator sst gradient in contrast the steep spathian sst gradient suggests latitudinally differentiated climatic conditions we propose that this drastic climate change and the global carbon cycle perturbation were triggered by a massive end smithian co2 injection the ssb event could therefore represent one of the causes for stepwise and delayed recovery of marine and terrestrial biotas in the wake of the end permian biotic crisis

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

lower middle triassic conodont biostratigraphy of the qingyan section guizhou province southwest china abstract the middle triassic qingyan formation at its type section the qingyan section of guizhou southwest china yields more than 300 species belonging to 17 fossil groups which mark the radiation of benthic organisms following the end permian mass extinction this study intends to establish a primary conodont biostratigraphical succession through the lower and middle triassic sequence at qingyan to provide a time framework for the understanding of the recovery and radiation process from the mass extinction a total of 30 species in 8 conodont genera are stratigraphically significant and assigned to the neospathodus dieneri neospathodus cristagalli neospathodus waageni neospathodus homeri chiosella timorensis and neogondolella cf bulgarica zones in ascending order most conodont zones correlate well with their counterparts recognized from elsewhere in china and even worldwide the first appearance of ns waageni marks the induan olenekian boundary which is placed at the lower middle part of the luolou formation 121 47 m above the permian triassic boundary the olenekian anisian early middle triassic boundary is here defined by the first occurrence of chiosella timorensis at the base of the qingyan formation although no conodonts retrieved from the upper qingyan formation containing the extraordinarily diverse biota i e the qingyan biota stratigraphical correlation with the neighbouring conodont bearing sections in guizhou and the ammonoid zones suggest that the qingyan biota has an age of early late anisian early middle triassic

diagenetic uptake of rare earth elements by bioapatite with an example from lower triassic conodonts of south china abstract the distribution patterns of rare earth elements rees are frequently used as proxies for ancient seawater chemistry or paleomarine environmental conditions however recent work has shown that diagenesis can lead to remobilization and inter elemental fractionation of rees and that these effects often occur in conjunction with redox reactions in sediment porewaters here we review existing literature on the diagenetic fluxes of rees in marine sediments and porewaters in order to systematize existing knowledge on this subject rees undergo significant redistribution among sediment phases during both early and late diagenesis as a consequence of adsorption and desorption processes remobilization of rees commonly leads to inter elemental fractionation variously leading to enrichment or depletion of the light middle or heavy ree fractions further ree remobilization can be facilitated by redox changes e g through reductive dissolution of host phases in suboxic and anoxic porewaters characteristic ree distribution patterns develop through these processes 1 a flat distribution signifying predominantly terrigenous siliciclastic influence 2 a middle ree bulge probably due to adsorption of light and heavy rees to mn and fe oxyhydroxides respectively and 3 heavy ree enrichment indicative of hydrogenous seawater influence note all patterns in this paper are normalized to the ree composition of average upper continental crust or ucc in the second part of this study we undertake an analysis of the ree distributions in conodonts and whole rock samples from west pingdingshan a permian triassic boundary section in south china using ree th and y ho ratios we show that almost all of the conodont samples have a strong diagenetic overprint and that the hydrogenous ree fraction is small and not isolatable furthermore the conodonts contain two diagenetic ree components one characterized by low ree 100 300 ppm high ree th ratios 1000 strong middle ree enrichment and eu eu ratios of 1 5 2 0 and the second by high ree 300 2000 ppm low ree th ratios 20 30 little or no middle ree enrichment and eu eu ratios of 1 0 the first component exhibits a pronounced middle ree bulge that represents an early diagenetic signature associated with suboxic conditions possibly related to adsorption of rees onto fe mn oxyhydroxides in the shallow subsurface environment the second component shows a flat ree distribution that is similar to both our whole rock samples and average ucc indicating derivation from rees released from detrital siliciclastics e g clay minerals probably at a range of burial depths from shallow to deep failure of the conodont samples to yield an isolatable hydrogenous component demonstrates that bioapatite does not always preserve a primary marine ree signature given that bioapatite rees have been widely used for this purpose often on the assumption of minimal or no diagenetic influence our findings are likely to necessitate a re evaluation of the results of many earlier studies in general we counsel caution in inferring a hydrogenous origin for rees in bioapatite owing to frequent diagenetic alteration of ree distributions

mercury anomalies associated with three extinction events capitanian crisis latest permian extinction and the smithian spathian extinction in nw pangea strata of permian early triassic age that include a record of three major extinction events capitanian crisis latest permian extinction and the smithian spathian extinction were examined at the festningen section spitsbergen over the c 12 ma record examined mercury in the sediments shows relatively constant background values of 0 005 0 010 g g 1 however there are notable spikes in hg concentration over an order of magnitude above background associated with the three extinctions the hg total organic carbon toc ratio shows similar large spikes indicating that they represent a true increase in hg loading to the environment we argue that these represent hg loading events associated with enhanced hg emissions from large igneous province lip events that are synchronous with the extinctions the hg anomalies are consistent across the nw margin of pangea indicating that widespread mercury loading occurred while this provides utility as a chemostratigraphic marker the hg spikes may also indicate loading of toxic metals to the environment a contributing cause to the mass extinction events

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

the lower triassic cyclic deposition in chaohu anhui province china abstract the lower triassic strata developed in chaohu anhui province of east central china including the yinkeng helongshan and nanlinghu formations is about 268 m thick and consists of carbonate rocks such as micrite limestone and nodular limestone as well as shale and argillaceous mudstone the deficiency of sedimentary structures and bioclastic particles and presence of pyrite and high ratios of v v ni suggest that the lower triassic strata formed in a quiet open marine basin environment bordering carbonate slope and lower slope within the lower triassic the cyclic deposits include two orders of thickening and coarsening upward successions respectively called basic unit bu and basic sequence bs which represent shallowing upward cycles five basic units are recognized and they are mostly composed of shale argillaceous mudstone calcareous mudstone and nodular limestone and overlying nodular limestone and micrite limestone about 0 25 1 4 m thick the shale and mudstone mainly formed in a deep water basin and the nodular limestone and micrite limestone formed on the rise of basin margin or the base of slope thus the basic units are interpreted to reflect cyclic sedimentation from the deep water basin to the rise of basin margin or from the rise to base of slope the basic units are combined with medium to thick bedded micrite limestones and thus form four types of basic sequences average 6 5 14 62 m thick likewise they are interpreted to be shallowing upward cycles with long period for example from the deep water of basin through the rise of basin margin to the base of slope farther reaching to lower slope the various orders of cycle in the lower triassic are laterally very extensive regionally which suggests that the fluctuation of sea level was likely a control on the origin of the cycles these small scale transgressive regressive cycles possibly reflect milankovitch cyclicity the associations of basic sequences constitute two transgressive regressive cycles which comprise strata of yinkeng helongshan and nanlinghu stages respectively which is similar to the carbon isotope cycles of the lower triassic tectonic activities can control the origin of the cycles the collision of south china block and north china block in the lower middle triassic may have resulted in the development of the two cycles and caused the shallowing upward sequence of the lower triassic from deep water basin to slope

evidence for end permian ocean acidification from calcium isotopes in biogenic apatite c record of carbonate rocks 13 c carb for the selective extinction of heavily calcifi ed marine animals and for the abrupt transition in carbonate facies across the extinction horizon an additional proxy is necessary to distinguish among these options calcium isotopes hold promise for differentiating between suggested scenarios for change in seawater carbonate chemistry linked with the end permian extinction the calcium cycle is linked to the carbon cycle through the weathering of limestone and the deposition of calcium carbonate sediments calcium isotopes fractionate by 0 6 and 1 3 in calcite and aragonite respectively during the precipitation of modern carbonate minerals meaning carbonate sediments are enriched in the lighter isotope relative to the seawater from which they precipitated skulan et al 1997 tang et al 2008 imbalances between calcium delivery and burial fl uxes and changes in the magnitude of fractionation during carbonate deposition will result in changes in the 44 40 ca of seawater and will be recorded in marine sediments depaolo 2004 farkao et al 2007 therefore variation in the

m sequence reversals recorded in dsdp sediment cores from the western mid pacific mountains and magellan rise new paleomagnetic and paleontologic data from pacific dsdp sites 463 and 167 define the magnetic reversals that predate the cretaceous normal polarity superchron k n data from mid pacific mountain site 463 provide the first definition of polarity chron m0 in the pacific deep sea sedimentary record foraminiferal biostratigraphy suggests that polarity chron m0 is contained entirely within the lower aptian hedbergella similis zone in agreement with foraminiferal data from the italian southern alps and atlantic ocean nannofossil assemblages also suggest an early aptian age for polarity chron m0 contrary to results from the italian umbrian apennines and southern alps which place polarity chron m0 on the barremian aptian boundary biostratigraphic dating discrepancies caused by the time transgressive preservational or provincial nature of paleontological species might be reconciled by the use of magnetostratigraphy specifically polarity chron m0 which lies close to the barremian aptian boundary at magellan rise site 167 five reversed polarity zones are recorded in hauterivian to aptian sediments correlation with m anomalies is complicated by synsedimentary and postsedimentary sliding about 25 m y after basement formation producing gaps in and duplications of the stratigraphic sequence the magnitude and timing of such sliding must be addressed when evaluating the stratigraphy of these oceanic rise environments

lower triassic δ13c isotope curve from shallow marine carbonates in japan panthalassa realm confirmation of the tethys δ13c curve abstract 13 c data from tethyan sections provide evidence of profound changes in the carbon cycle during the lower triassic sections from the panthalassa realm were investigated to establish whether these variations are also present there in the jurassic accretionary wedges in japan exotic blocks having a panthalassan affinity have been incorporated the majority of the blocks are pelagic cherts but rare shallow water carbonates are also present we present a 13 c study on the lower triassic of a shallow water carbonate succession deposited on a mid oceanic seamount and accreted to the chichibu belt japan two sections have been measured at kamura central kyushu island the carbon isotope curve shows depleted values across the permian triassic boundary ptb subsequently followed by an increase to heavier values into the dienerian culminating in a maximum of almost 4 v pdb before a steep drop at a stratigraphic gap low values are recorded in the smithian but rise to enriched 13 c values 3 5 near the smithian spathian boundary the observed trend of the stable carbon isotope curve from japanese sediments mirrors the curves derived from sections in the tethys e g italy iran turkey oman and the south china nanpanjing basin our results support the interpretation of this curve as representing a global trend across the ptb and in the lower triassic although some distinct features are absent around the dienerian smithian boundary profound variations of the carbon isotope curve in the lower triassic are presented for the first time from a marine section outside of the tethys they indicate severe global changes in the lower triassic carbon cycle and the causative processes must have significantly contributed to the delayed biotic recovery after the ptb large amounts of carbon were shifted between carbon reservoirs most probably between shallow and deep ocean waters and or ocean and sediment anoxia followed by overturn of the ocean water masses may have been the mechanism which quickly altered ecological conditions in the ocean leading to variable availability of nutrients and oxygen and changes in isotope composition of the available carbon in the surface waters that was incorporated in the precipitated carbonate

an integrated biostratigraphy conodonts and foraminifers and chronostratigraphy paleomagnetic reversals magnetic susceptibility elemental chemistry carbon isotopes and geochronology for the permian upper triassic strata of guandao section nanpanjiang basin south china abstract the chronostratigraphy of guandao section has served as the foundation for numerous studies of the end permian extinction and biotic recovery in south china guandao section is continuous from the permian triassic boundary to the upper triassic conodonts enable broad delineation of stage and substage boundaries and calibration of foraminifer biostratigraphy as follows changhsingian griesbachian first hindeodus parvus and first appearance of foraminifers postcladella kalhori and earlandia sp griesbachian dienerian first neospathodus dieneri and last appearance of foraminifer p grandis dienerian smithian first novispathodus waageni and late dienerian first appearance of foraminifer hoyenella ex gr sinensis smithian spathian first nv crassatus and last appearance of foraminifers arenovidalina n sp and glomospirella cf vulgaris spathian aegean first chiosella timorensis and first appearance of foraminifer meandrospira dinarica aegean bithynian first nicoraella germanica and first appearance of foraminifer pilammina densa bithynian pelsonian after last neogondolella regalis prior to first paragondolella bulgarica and first appearance of foraminifer aulotortus eotriasicus pelsonian illyrian first pg excelsa and last appearance of foraminifers meandrospira deformata and pilamminella grandis illyrian fassanian first budurovignathus truempyi and first appearance of foraminifers abriolina mediterranea and paleolituonella meridionalis fassanian longobardian first bv mungoensis and last appearance of foraminifer a mediterranea longobardian cordevolian first quadralella polygnathiformis and last appearance of foraminifers turriglomina mesotriasica and endotriadella wirzi the section contains primary magnetic signature with frequent reversals occurring around the permian triassic olenekian anisian and anisian ladinian boundaries predominantly normal polarity occurs in the lower smithian bithynian and longobardian cordevolian predominantly reversed polarity occurs in the upper griesbachian induan olenekian pelsonian and lower illyrian reversals match well with the gpts large amplitude carbon isotope excursions attaining values as low as 2 9 13c and high as 5 7 13c characterize the lower triassic and basal anisian values stabilize around 2 13c through the anisian to carnian similar signatures have been reported globally magnetic susceptibility and synthetic gamma ray logs show large fluctuations in the lower triassic and an overall decline in magnitude of fluctuation through the middle and upper triassic the largest spikes in magnetic susceptibility and gamma ray indicating greater terrestrial lithogenic flux correspond to positive 13c excursions high precision u pb analysis of zircons from volcanic ash beds provide a robust age of 247 28 0 12 ma for the olenekian anisian boundary at guandao and an age of 251 985 0 097 ma for the permian triassic boundary at taiping together the new u pb geochronology from the guandao and taiping sections suggest an estimated duration of 4 71 0 15 ma for the early triassic epoch

triassic ammonoid biostratigraphy an overview abstract the triassic chronostratigraphic scale was built on two centuries of research on ammonoid biostratigraphy and biochronology two triassic stage bases and all of the triassic substages are currently defined by ammonoid bioevents the study of triassic ammonoids began during the late 1700s and in 1895 edmund von mojsisovics wilhelm waagen and carl diener published an essentially complete triassic chronostratigraphic scale based on ammonoid biostratigraphy this scale introduced many of the triassic stage and substage names still used today and all terminology of stages and substages subsequently introduced has been based on ammonoid biostratigraphy early triassic ammonoids show a trend from cosmopolitanism induan to latitudinal differentiation olenekian and the four lower triassic substage griesbachian dinerian smithian and spathian boundaries are globally correlated by widespread ammonoid biotic events middle triassic ammonoids have provinciality similar to that of the olenekian and provide a basis for recognizing six middle triassic substages late triassic ammonoids provide a basis for recognizing three stages divided into five substages the main uncertainty for the future of triassic ammonoid biostratigraphy is not the decline of the ammonoids as a tool for dating and correlation of triassic strata but rather the dramatic decrease in the number of specialists due to the lack of replacement of experienced palaeontologists who started their activity in the 1950s and 1960s

organic matter and palaeoenvironmental signals during the early triassic biotic recovery the salt range and surghar range records latest permian to the middle triassic mixed siliciclastic carbonate shelf deposits of the northern gondwana margin have been studied in four sections nammal chhidru chitta landu and narmia in the salt range and surghar range of pakistan sedimentological and palynofacies patterns combined with a high resolution ammonoid based age control have been used to assess environmental changes such as sea level change distance from the shore and oxygenation conditions of the sections in the aftermath of the end permian mass extinction the base and the top of the early triassic are marked by second order sequence boundaries srt1 srt8 within the early triassic two third order sequence boundaries could be delineated by means of palynofacies analysis and sedimentology one near the dienerian smithian srt2 and the second one near the smithian spathian boundary srt5 the extinction event at the smithian spathian boundary seems to be closely associated to the latter globally recorded sea level low stand five additional sequences of undetermined order srt3 srt 4 srt5 1 srt6 and srt7 are reflected in the sedimentological record of the studied sections the observed changes in the composition of the particulate organic matter pom indicate a general shallowing upward trend which is modulated by smaller transgressive regressive cycles supporting the sedimentologically defined sequences the pom is mostly dominated by terrestrial phytoclasts and sporomorphs the strongest marine signal is reflected by increased abundance of amorphous organic matter aom in the lower part of the ceratite marls at nammal late dienerian and chhidru earliest smithian and the lower ceratite limestone at chitta landu late dienerian aom of marine origin is characteristic for deeper distal basinal settings and is preferentially preserved under dysoxic and anoxic conditions indicating reduced oxygen conditions during these intervals up section transgressive events are reflected by increased numbers of acritarchs reaching up to 50 of the pom well oxygenated conditions and low total organic carbon contents toc continue up to the top of the early triassic mianwali formation the most pronounced terrestrial influx is expressed in the middle triassic organic carbon isotope data parallel the carbonate carbon isotope records from the tethyan realm therefore they reflect real global changes in the carbon cycle independent of the om composition the biomarker study of the apolar hydrocarbons of three samples from the nammal section indicates an enhanced bacterial productivity especially in the smithian and spathian reflected in high relative abundances of hopanes pom toc data and redox sensitive biomarkers together with high resolution biostratigraphy demonstrate that well oxygenated environmental conditions prevailed in the early triassic with the exception of the dienerian to earliest smithian interval the pom assemblages of late permian to late griesbachian age indicate well oxygenated conditions during this time interval there is no evidence in support of an anoxic event in the late griesbachian in these sections

developing a strategy for accurate definition of a geological boundary through radio isotopic and biochronological dating the early middle triassic boundary south china abstract the ages of critical periods in the geological record of the earth have to be determined and attached uncertainties quantified as precisely and accurately as possible this study tries to find an optimal strategy for sampling for both biochronology and high precision u pb analysis of zircon from ash beds and for the selection and statistical treatment of geochronological data this strategy is applied to the case of the early middle triassic boundary emtb in the southern nanpanjiang basin in south china aiming to obtain the most accurate age information for this boundary with an associated uncertainty the emtb has been located in a sedimentary section near monggan guangxi south china which permitted tight correlation between conodont biozones the carbon isotopic record and high precision zircon u pb data from volcanic ashes two residual maximal horizons were defined using characteristic associations of conodont species accurately bracketing the emtb the lower and upper age limits of these horizons as well as the first occurrence fo of the base middle triassic index fossil chiosella timorensis were numerically calibrated by high precision chemical abrasion isotope dilution thermal ionization mass spectrometry ca id tims u pb dates volcanic zircon in the analyzed ash beds reveals complex system behavior in particular i unresolved lead loss after chemical abrasion and ii pre eruptive growth and or recycling of zircon crystals leading to excess scatter in 206 pb 238 u dates and to violations of the stratigraphic sequence a sufficiently high number of closely spaced ash samples n and of u pb analyses per sample n promotes recognition of such complications two different age models were constructed from weighted mean 206 pb 238 u dates comparing smoothing cubic spline and bayesian interpolation approaches the statistical treatment of the combined datasets allows quantification of the lower and upper limits and associated uncertainties of the two conodont biozones as well as of the fo of c timorensis the age for the emtb is calculated from combined interpolated data at 247 05 0 16 ma the age model derived from bayesian interpolation is considered to be more adapted to the present case where discontinuous changes in sedimentation rates are expected to be important the smoothing spline represents a more parsimonious model producing a simpler solution in terms of smoothness but the model assumptions are too strong for many geological problems the additional freedom in constructing the bayesian interpolating curve presumably leads to more realistic albeit larger confidence intervals

early triassic conodonts of jiarong nanpanjiang basin southern guizhou province south china abstract jiarong huishui county guizhou province south china is a key locality for the study of the early triassic recovery after the end permian mass extinction the size reduction of conodonts at the smithian spathian transition was first documented in jiarong and it is also a locality that contributes to the documentation of the early triassic paleo seawater temperatures in the jiarong sections thirteen conodont zones were identified for the early triassic in ascending order they are hindeodus parvus zone hindeodus sosioensis zone clarkina krystyni zone neoclarkina discreta zone neospathodus cristagalli eurygnathodus costatus assemblage zone novispathodus waageni eowaageni zone novispathodus waageni waageni zone discretella discreta zone pachycladina parachirognathus assemblage zone novispathodus pingdingshanensis zone icriospathodus collinsoni zone triassospathodus homeri zone triassospathodus triangularis zone these conodont zones in the jiarong sections improve the global correlation of early triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction based on the first appearance of nv waageni eowaageni the induan olenekian boundary is recognized at 3 6 m above the base of the jiarong iii section the dominance of blade shaped segminate conodonts was replaced by gondola shaped segminiplanate conodonts twice the first time was in the late griesbachian and the second time was in the early spathian the dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late griesbachian and early spathian for short time intervals as it is believed that the griesbachian segminiplanate conodonts favored deeper oxygenated water habitats a new genus spathogondolella gen nov and a new species spathogondolella jiarongensis sp nov have been recognized

marine productivity changes during the end permian crisis and early triassic recovery abstract the latest permian mass extinction lpme coincided with major changes in the composition of marine plankton communities yet little is known about concurrent changes in primary productivity earlier studies have inferred both decreased and increased productivity in marine ecosystems immediately following the end permian crisis here we assess secular and regional patterns of productivity variation during the crisis through an analysis of the burial fluxes of three elemental proxies total organic carbon toc phosphorus p and biogenic barium babio primary productivity rates appear to have increased from the pre crisis late permian through the early triassic in many parts of the world although the south china craton is unusual in exhibiting a pronounced decline at that time most of the 14 permian triassic study sections show concurrent increases in sediment bulk accumulation rates suggesting two possible influences linked to subaerial weathering rate changes 1 intensified chemical weathering resulting in an increased riverine flux of nutrients that stimulated marine productivity and 2 intensified physical weathering leading to higher fluxes of particulate detrital sediment to continental shelves thus enhancing the preservation of organic matter in marine sediments an additional factor especially in the south china region may have been the intensified recycling of bacterioplankton derived organic matter in the ocean surface layer reducing the export flux rather than primary productivity per se the ecosystem stresses imposed by elevated fluxes of nutrients and particulate sediment as well as by locally reduced export fluxes of organic matter may have been important factors in the 2 to 5 million year long delay in the recovery of early triassic marine ecosystems

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

petrological characteristics of archean graywackes abstract in terms of qfr and alkali element k na relationships most archean graywackes are similar to phanerozoic quartz intermediate graywackes however a number of important differences preclude direct comparisons felsic volcanic rock fragments greatly outweigh andesitic rock fragments in archean graywackes whereas the reverse is seen in phanerozoic examples in comparison to phanerozoic quartz intermediate graywackes archean graywackes tend to have about 5 lower silica contents a dominantly volcanogenic provenance can be documented for several archean graywacke suites in almost all examples plagioclase dominates over k feldspar but this alone cannot be taken as evidence for a volcanic source because early archean granitic rocks are typically sodium rich tonalites trondhjemite the abundance of quartz in most archean graywackes q typically 40 is indicative of a major granitic component archean graywackes tend to have high feo mgo values typically 8 0 and in this respect are similar to quartz poor graywackes or modern sands deposited in fore arc basins it is suggested that these high values represent moderate amounts of mafic volcanic debris which have degraded to form part of the matrix thus many archean graywackes appear to have been derived from the well established igneous bimodal suite mafic volcanics na granites felsic volcanics characteristic of many archean terranes the petrological differences between archean graywackes and their younger counterparts preclude direct interpretations of tectonic setting but the petrology of many archean graywackes is consistent with deposition at the edge of continents

a new high resolution δ13c record for the early triassic insights from the arabian platform a new carbon isotope record with conodont biostratigraphy is presented for the entire early triassic from the musandam peninsula united arab emirates uae this is a near continuous and exclusively shallow marine carbonate succession that allows analysis of a high resolution primary carbon cycling signature in the absence of significant depth dependent or lithologic controls the musandam carbon isotope record can be broadly correlated with global isotopic events but also resolves additional features including the presence of significant negative events during the previously identified positive excursions at both the dienerian smithian and smithian spathian boundaries a further positive event is revealed during the development of the mid spathian negative excursion a feature not previously reported in any other section these new short lived events are probably related to the occurrence of the more widely recognized early triassic excursions and may represent fluctuations in the driving mechanisms superimposed on the continued instability of the global carbon cycle in the aftermath of the end permian extinction together these features highlight additional complexities to the early triassic carbon cycle perturbations than previously documented

marine triassic faunas of north america their significance for assessing plate and terrane movements the distribution of marine triassic invertebrate faunas in north america is reviewed to recognize forms that may have paleolatitudinal significance

evolution of early triassic outer platform paleoenvironments in the nanpanjiang basin south china and their significance for the biotic recovery detailed microfacies and paleoenvironmental analyses were conducted through the early triassic interval of the outer platform ammonoid rich series of the nanpanjiang basin luolou formation guangxi province south china extensive investigations on outcrops and on thin sections reveal that the widely reported well diversified latest permian fauna dominated by abundant corals calcareous algae calcareous sponges crinoids brachiopods gastropods ostracods and foraminifera is abruptly replaced by decimated early triassic communities essentially composed of low diversity bivalves microgastropods ostracods and rare foraminifera along with this drastic change in faunal assemblages the recolonization of devastated habitats by calcimicrobial frameworks is observed in the aftermath of the end permian mass extinction calcimicrobialites of griesbachian age are followed by mixed ammonoid and conodont rich carbonate siliciclastic series consisting of dark suboxic laminated mudstones intercalated with organic rich shales of dienerian to late smithian age the carbonate siliciclastic series are interrupted by a brief carbonate episode during the early middle smithian massive carbonate production resumes only from the early spathian onward and persists throughout the spathian the initial deposition of both carbonate episodes is coeval with i re establishment of well oxygenated conditions ii a marked early smithian to extreme early spathian ammonoid conodont diversification iii a significant increase in the skeletal grain diversity and abundance and iv peak carbon isotope values a short interval of black organic rich shales precedes the onset of these two distinct carbonate events which are both marked by a positive carbonate carbon isotope excursion known from other tethyan marine localities the comparison between the early triassic stratigraphic evolution of tethyan outer platform paleoenvironments and platform basin margin settings of the nanpanjiang basin suggests a causal connection between large fluctuations of the global carbon cycle climate shifts sea level changes oxygen availability in the oceans and the biological rediversification in the wake of the end permian biotic crisis

high resolution biochronology and diversity dynamics of the early triassic ammonoid recovery the smithian faunas of the northern indian margin a new high resolution biozonation based on the unitary association ua method is constructed for the dienerian ammonoid succession of the northern indian margin it includes 12 ua zones and leads to the subdivision of the dienerian into three parts early middle and late the corresponding diversity analyses coupled with results previously obtained for the early smithian ammonoids of the same regions highlight the four following phases 1 a first modest peak of diversity in the early dienerian 2 a very low diversity persisting throughout the middle dienerian 3 a slow increase of diversity during the late dienerian and 4 a marked diversification in the early smithian turnover rates are very high during this entire time interval and the boundaries between early middle and middle late dienerian are emphasised by complete renewals of the ammonoid faunas the low diversity values in the middle and early late dienerian are concomitant with an anoxic event on outer continental shelves and coincide with warmer temperatures than those of the early dienerian and early smithian this diversity pattern stands in strong contrast with the credo of a protracted or stepwise recovery following the end permian mass extinction together with the end smithian extinction the middle and early late dienerian diversity crises were likely both radical setbacks in the recovery of early triassic ammonoids however these two diversity crises do not necessarily imply identical environmental triggers that ultimately led to anoxic bottom waters on outer continental platforms in both cases

panthalassic oceanic anoxia at the end of the early triassic a cause of delay in the recovery of life after the end permian mass extinction abstract fossil data show that the recovery of life after the end permian mass extinction occurred in the anisian early middle triassic the process by which oceanic environments recovered from anoxia after the end permian event is uncertain to determine the timing of known recovery stages the nature of oceanic redox conditions and the health of cyanobacterial plankton populations this study analyses conodonts and organic molecules from siliceous claystones and cherts from accretionary complexes in japan that span the upper lower triassic to the lowermost middle triassic conodonts indicate that the study section ranges from upper olenekian to anisian and includes the olenekian anisian boundary an increase in polycyclic aromatic hydrocarbons probably derived from algae dominated organic matter and a decrease in methylhopane index 2 methylhopane hopane a measure of cyanobacterial activity are present in end olenekian black chert pristane phytane ratios a measure of redox conditions in all stratigraphic units are lower than 1 indicating the prevalence of deep sea anoxia during the late olenekian to anisian high concentrations of dibenzothiophene an index of anoxic depositional environments high sulphur carbon ratios and high organic carbon contents are present in two upper olenekian intervals and at the end of the upper olenekian suggesting development of anoxic deep water one of the anoxic events in the end of the upper olenekian coincided with decreased radiolarian diversity this implies that anoxic deep water in the panthalassic ocean reached intermediate water depths at the end of the early triassic killing marine organisms including radiolaria this event may be related to the delay in the recovery of life and environments after the end permian mass extinction

biomagnetostratigraphy of the vikinghogda formation svalbard arctic norway and the geomagnetic polarity timescale for the lower triassic a bio magnetostratigraphy for the lower triassic is constructed using the ammonoid biostratigraphy from arctic boreal successions combined thermal and alternating field demagnetisation determines the triassic magnetic field polarity in 86 of specimens with 36 showing linear trajectory line fits and the remainder great circle trends towards the characteristic magnetisation mean pole directions for the deltadalen 50 159 dp dm 3 9 5 1 lusitaniadalen 56 163 dp dm 4 4 5 4 and vendomdalen 57 143 dp dm 4 4 5 4 members fall close to the european lower triassic apparent polar wander path mean directions for two of these member means pass the reversal test the remanence is predominantly carried by magnetite the polarity stratigraphy when integrated with the ammonoid and meager conodont data is similar to that determined from successions in the sverdrup basin canada the permian triassic boundary post dates a pronounced palynofloral turnover and pre dates a short duration reverse magnetozone lt1n 1r in the correlated shangsi section in s china lt1n 1r occurs after the fad of h parvus but in the arctic is within the otoceras boreale zone the late griesbachian to early smithian is mostly reverse polarity with three normal polarity intervals overlain by mid and late smithian normal polarity the spathian contains four reverse polarity intervals the oldest one within the early spathian with the remainder in the late spathian transition into the anisian is within the uppermost reverse magnetozone a feature documented in other sections of this age the polarity pattern is correlated to other marine sections indicating the robustness of the bio magnetostratigraphic composite and its utility in calibrating lower triassic time

the triassic timescale new constraints and a review of geochronological data a review of geochronological data underlying the geological time scale for the triassic yields a significantly different time scale calibration than that published in the most recent compi lation geologic time scale 2004 this is partly due to the availability of new radio isotopic data but mostly because strict selection criteria are applied and complications arising from biases both systematic and random are accounted for in this contribution the ages for the base and the top of the triassic are constrained by u pb ages to 252 3 and 201 5 ma respectively these dates also constrain the ages of major extinction events at the permian triassic and triassic jurassic bound aries and are statistically indistinguishable from ages obtained for the siberian traps and volcanic products from the central atlantic magmatic province respectively suggesting a causal link ages for these continental volcanics however are mostly from the k ar 40 ar 39 ar system which requires accounting and correcting for a systematic bias of c 1 between u pb and 40 ar 39 ar isotopic ages the 40 ar 39 ar ages being younger robust age constraints also exist for the induan olenekian boundary 251 2 ma and the early middle triassic olenekian anisian boundary 247 2 ma resulting in a surprisingly short dur ation of the early triassic which has implications for the timing of biotic recovery and major changes in ocean chemistry during this time furthermore the anisian ladinian boundary is con strained to 242 0 ma by new u pb and 40 ar 39 ar ages radio isotopic ages for the late triassic are scarce and the only reliable and biostratigraphically controlled age is from an upper carnian tuff dated to 230 9 ma yielding a duration of more than 35 ma for the late triassic all of these ages are from u pb analyses applied to zircons with uncertainties at the permil level or better the resulting compilation can only serve as a guideline and must be considered a snapshot resolving some of the issues mainly associated with inaccurate and misinterpreted data in previous publi cations however further advances will require revision of some of the data presented here

environmental and diagenetic variations in carbonate associated sulfate an investigation of cas in the lower triassic of the western usa an integrated stable isotope elemental and petrographic analysis of early triassic spathian carbonates and evaporites along a proximal to deep environmental transect reveals significant variations in 34s composition of carbonate associated sulfate cas the variations in the 34s of cas are strongly correlated with the ca mg composition of carbonates suggesting that the variations are driven by the degree of dolomitization the 34s of dolostones and evaporites are similar to one another and exhibit lower 34s values than limestones from all localities three hypotheses may explain the differences in 34s between proximal dolostones evaporites and inner middle shelf limestones 1 limestones experienced anaerobic sulfate reduction and subsequent incorporation of 34s enriched sulfate into cas during diagenesis while dolostones did not this is unlikely because of the lack of correlation between 34scas and toc as well as other indicators of diagenesis 2 dolomitization controlled the 34scas in proximal paleoenvironments where the source of the 34s depleted fluids was either continentally derived or the result of rayleigh distillation during evaporite formation and 3 a 34s depth gradient existed during the early triassic such that limestones formed in distal waters are more enriched in 34s versus evaporites and dolostones formed in proximal settings we do not favor this hypothesis because the strong correlation between ca mg and 34scas implies that dolomitization controls the 34scas in these samples results from subtidal well preserved non dolomitized limestones suggest that the 34s of spathian seawater sulfate may have been heavier than previously suggested from analyses of evaporite deposits alone

first record of hindeodus isarcicella population in lower triassic of slovenia abstract this study documents the permian triassic boundary in the iri area of western slovenia a paleontological study of the lukac section northwest of iri resulted in the recovery of a variety of microfossils this report documents the conodont fauna recovered from the section this is the first report of the hindeodus isarcicella population in slovenia and it provides important new biostratigraphic data for the definition of the permian triassic boundary hindeodus parvus has been recovered and its first appearance in the lowermost werfen formation indicates the base of the triassic period based on the conodont taxa h parvus hindeodus typicalis hindeodus sp isarcicella isarcica isarcicella lobata isarcicella staeschei isarcicella turgida and isarcicella sp a at least three faunas can be distinguished and they make possible a worldwide correlation