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

40ar 39ar geochronological constraints on the age and evolution of the permo triassic emeishan volcanic province southwest china abstract the biostratigraphically constrained permo triassic emeishan volcanic province evp extending over wide areas in southwest china has been recently considered as a large igneous province contemporaneous with the siberian traps and the siliceous tuffs at the p t boundary in south china we report the first 40ar 39ar ages on this igneous province minimum ages have been obtained on phenocrystic plagioclase of the emeishan basalt which has undergone a pervasive metamorphism most likely during subsequent tectonization as a consequence of terrane amalgamation comparison between the ar release spectra obtained on clear vs cloudy plagioclase indicates a 40 30 ma sericite resetting time a minimum apparent age of 246 4 ma for plagioclase from a plagiogranite a late differentiate of the panzhihua layered complex and an age of 254 5 ma for phlogopite from a pyroxenite near lake erhai provide the first absolute age constraint on this igneous province additional ar ar age measurements on post emeishan alkaline and mafic magmatism yielded 104 2 and 100 2 ma for an alkaline complex near panzhihua and 42 1 ma for a gabbro sill emplaced near the ertan dam further study is still needed to determine the age of the emeishan volcanic emission accurately and to test the validity of the assumed short duration of the eruption

the end permian mass extinction a rapid volcanic co2 and ch4 climatic catastrophe abstract the end of the permian was a time of crisis that culminated in the earth s greatest mass extinction there is much speculation as to the cause for this catastrophe here we provide a full suite of high resolution and coeval geochemical results trace and rare earth elements carbon oxygen strontium and clumped isotopes reflecting ambient seawater chemistry and water quality parameters leading up to the end permian crisis preserved brachiopod low mg calcite based seawater chemistry supplemented by data from various localities documents a sequence of interrelated primary events such as coeval flows of siberian trap continental flood basalts and emission of carbon dioxide leading to warm and extreme greenhouse conditions with sea surface temperatures sst of 36 c for the late permian although anoxia has been advanced as a cause for the mass extinction most biotic and geochemical evidence suggest that it was briefly relevant during the early phase of the event and only in areas of upwelling but not a general cause instead we suggest that renewed and increased end permian siberian trap volcanic activity about 2000 years prior to the extinction event released massive amounts of carbon dioxide and coupled with thermogenic methane emissions triggered extreme global warming and increased continental weathering eventually these rapidly discharged greenhouse gas emissions less than 1000 years before the event ushered in a global hothouse period leading to extreme tropical ssts of 39 c and higher based on these sea surface temperatures atmospheric co 2 concentrations were about 1400 ppmv and 3000 ppmv for the late and end permian respectively leading up to the mass extinction there was a brief interruption of the global warming trend when sst dropped concurrent with a slight but significant recovery in biodiversity in the western tethys it is possible that emission of volcanic sulfate aerosols resulted in brief cooling just after the onset of intensified warming during the end of the permian after aerosol deposition global warming resumed and the biotic decline proceeded and was accompanied by suboxia in places of the surface ocean which culminated in the greatest mass extinction in earth history

excess 40ar in biotite and hornblende from the noril sk 1 intrusion siberia implications for the age of the siberian traps the siberian traps represent the largest known phanerozoic manifestation of continental flood volcanism the general agreement is now that the volcanism was of short duration 1 m y and was synchronous with the permian triassic boundary discrepancies between different geochronologic results prevent rigorous evaluation of the age and duration of magmatism several alkalic mafic intrusions associated with the siberian traps represent subvolcanic feeders for the trap lavas the noril sk 1 intrusion is intruded into the earliest flows and is chemically and isotopically related to stratigraphically overlying flows biotites from the noril sk 1 intrusion have previously yielded 40ar39ar plateau dates 254 251 ma that are significantly older than seemingly reliable 40ar39ar plateau dates 250 247 ma on plagioclase and whole rock samples from trap basalts that are geologically constrained to be older than the intrusion possible explanations of this discrepancy include 1 plagioclase and whole rock samples are anomalously young due to 40ar loss via alteration or episodic outgassing and or 2 the biotites contain excess 40ar detailed laser heating 40ar39ar analysis of six individual grains of biotite in a total of 214 steps yield data that permit characterization of multiple components of ar through isotope correlation patterns an isochron age of 250 1 1 5 ma 2 and an excess ar component with 40ar36ar 565 39 are obtained by regression of the 115 highest temperature steps step heating of a bulk hornblende sample also reveals excess ar with 40ar36ar 327 10 and an isochron age of 249 3 1 6 ma neglecting uncertainties in the ages of neutron fluence monitors the two dates just overlap at 2 but are distinctly younger than the previous mean plateau date 253 9 1 6 ma for biotite the different initial 40ar36ar for the two phases is interpreted as reflecting the evolution of an initial lower mantle composition towards increasing crustal contamination

griesbachian earliest triassic palaeoenvironmental changes in the salt range pakistan and southeast china and their bearing on the permo triassic mass extinction abstract facies and faunal analysis from pakistan and china show that the permo triassic mass extinction of marine invertebrate faunas was associated with a spectacularly rapid griesbachian transgression which lead to the widespread establishment of deep water anoxic and dysoxic conditions the extinction event was thus caused by habitat loss due to the extensive development of inhospitable conditions the initial griesbachian transgression in pakistan produced extensive shallow normal marine conditions in which permian holdover taxa were able to survive until the development of dysaerobic facies in the late griesbachian the exceptionally complete sections of china show a three phased deepening and extinction event beginning in the latest permia by the late griesbachian a variety of dysaerobic and anaerobic facies were developed in all the regions studied several of these contain evidence for minimal sulphate reducing activity suggesting that marine productivity and thus organic matter flux to the sediments was very low in early triassic seas

palaeoecology of the conodonts hindeodus and clarkina during the permian triassic transitional period abstract detailed investigation of the distributions of the hindeodus and clarkina neogondolella conodont faunas has been undertaken on the p t boundary strata of the meishan section zhejiang province south china in association with detailed facies analysis this reveals that hindeodus increased and clarkina sharply declined in abundance during a phase of relative sea level rise which began at the end permian bed 25 and extended into early triassic this was associated with the development of anoxic conditions this distribution does not accord with previous suggestions that hindeodus was a nearshore shallow water taxon the decline of the supposed deeper water genus clarkina is also somewhat surprising but it may relate to the inhibition of a nektobenthic genus by dysoxic anoxic bottom waters the widespread facies and geographic distribution of hindeodus suggests it was a pelagic type unaffected by anoxic bottom waters hence the hindeodus lineage provides a reliable criterion for identification of the permian triassic boundary

sources of sr and s in aluminum phosphate sulfate minerals in early middle triassic sandstones iberian ranges spain and paleoenvironmental implications for the west tethys aluminum phosphate sulfate aps minerals formed during early diagenesis in relation to acid meteoric waters are the main host of sr and s in the early middle triassic continental sandstones of the iberian ranges east of the iberian peninsula the sources of these elements and the effects of paleoenvironmetal changes on these sources and on the formation of aps minerals during early middle triassic times were established on the basis of sr and s isotopic analyses the s and sr data d34s v cdt 11 to 14 and 87sr 86sr 0 7099 0 7247 respectively can be interpreted as resulting from mixing of different sources strontium was sourced from the dissolution of pre existing minerals like k feldspar and clay minerals inherited from the source areas causing high radiogenic values however the isotopic signal must also be influenced by other sources such as marine or volcanic aerosol that decreased the total 87sr 86sr ratios marine and volcanic aerosols were also sources of sulfur but the d34s was lowered by dissolution of pre existing sulfides mainly pyrite pyrite dissolution and volcanic aerosols would also trigger the acid conditions required for the precipitation of aps minerals aps minerals in the study area are found mainly in the canizar formation olenekian aegian which has the lowest 87sr 86sr ratios the lower abundance of aps minerals in the eslida formation aegian pelsonian may indicate change in the acidity of pore water towards more alkaline conditions while the increased 87sr 86sr ratios imply decreased sr input from volcanic activity and or marine aerosol inputs during anisian times therefore the decrease in abundance of aps minerals from the early to middle triassic and the variations in the sources of sr and s are indicative of changes in paleoenvironmental conditions during the beginning of the triassic period these changes from acid to more alkaline conditions are also coincident with the first appearance of carbonate paleosols trace fossils and plant fossils in the upper part of the canizar formation and more in the overlying eslida formation and mark the beginning of biotic recovery in this area the presence of aps minerals in other european basins of the western tethys such as the german basin the paris basin and the southeastern france and sardinia basins could thus also indicate that unfavorable environmental conditions caused delay in biotic recovery in those areas in general the presence of aps minerals may be used as an indicator of arid acidic conditions unfavorable to biotic colonization

stratigraphical and palaeogeographical significance of the continental sedimentary transition across the permian triassic boundary in spain abstract the permian triassic transition a time of phenomenal palaeoenvironmental and palaeogeographical change represents the largest episode of mass extinctions known to palaeontologists this episode is however very poorly understood and a lack of sediments and palaeontological data particularly in the continental record is a feature common to every basin despite compelling information on the continental permian triassic boundary ptb emerging from recent efforts evaluating vertebrate evolution fungal events and isotope curves results are still insufficient to make any valuable correlations among continental basins and are even less appropriate for relating sediments of continental to those of marine origin the present report discusses and attempts to locate the ptb in the basins of iberia and balearic islands through an analysis of the palaeontological and sedimentary record across the permian triassic transition the aim of the paper is to contribute to our present knowledge of the palaeogeographical and stratigraphical significance of the permian and triassic continental units of western europe the present day iberian ranges catalonian ranges and balearic islands hold the most complete late permian early triassic sedimentary record in iberia this record consists of alluvial sediments mainly of braided fluvial systems corresponding to the saxonian and buntsandstein facies all the units examined so far have been dated through palynological associations the two saxonian facies formations are of thuringian age although the lower one shows some palynological elements of autunian affinities the buntsandstein units range from thuringian to anisian in age there being no evidence up to now of the scythian in iberia the exact position of the ptb in iberia is up to now impossible to pinpoint with the precision of the marine series sedimentary characteristics and palynological data in the iberian ranges point that it lies at the sedimentary interval 10 to 30 m thick formed by the upper member of the la hoz del gallo formation and the lowermost beds of the canizar formation or its time equivalent the prades and eramprunya units in the catalonian ranges and the asa and b 1 in the balearic islands we compare a normalized standard late permian middle triassic column of the iberian ranges with standards from western and central europe and the southern urals using recent permian time scales a palaeogeographic essay map of the permian triassic transition is provided for the iberian plate the plate was located in a northern subtropical position 200 400 km from the westernmost tethys coast as part of the central pangean mountain range comprised of the appalachian mauretanide variscan orogenic belts of estimated altitudes 2000 4000 m based on this palaeogeographic location sedimentary characteristics and the main wind flows established for the tethys we can infer conditions of high precipitation dominated by monsoon and seasonal regimes with isolated semiarid areas for the iberian plate during the transition

paleozoic and triassic conodonts from the northwind ridge of the arctic ocean abstract conodonts are present in the basal part of six arctic ocean sediment cores recovered from the northwind ridge in the chukchi borderland area of the western arctic ocean the conodonts include species typical of the upper cambrian lower and middle ordovician middle to upper pennsylvanian probable lower middle and upper permian and lower triassic most of the conodont elements including a few of the cambro ordovician and all of the upper permian species were recovered from the sand fraction of the northwind breccia in the basal 1 5 m of core 92 p34 other ordovician and younger paleozoic conodont specimens occur in carbonate clasts incorporated in the northwind breccia the talus breccia occurs in the lower part of the early pliocene miocene unit a undifferentiated and is overlain unconformably by pleistocene age sediment a few paleozoic and triassic conodonts also occur in clasts recovered from the basal parts of five other northwind ridge cores upper permian specimens are the most numerous of the conodont elements and occur together with an abundant ichthyolith assemblage in addition the sand fraction of the northwind breccia contains poorly preserved foraminifera holothurians and sponges spicules that are common in all arctic ocean plio pleistocene sediment occurrence of conodonts in what is interpreted to be talus derived from bedrock indicates that the enigmatic northwind ridge is a true continental fragment that includes marine strata of at least paleozoic and triassic age the nature of the conodonts and other fossils recovered from the breccia suggests that the northwind ridge originated as part of the canadian arctic islands

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

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

magnetostratigraphy and high resolution lithostratigraphy of the permian triassic boundary interval in central germany abstract a comprehensive lithostratigraphic and magnetostratigraphic study was carried out in order to provide a magnetic polarity scale for the lower buntsandstein of the classic germanic trias in its type area of central germany the 300 m thick lower buntsandstein consists of 20 small scale fining upward cycles they can be correlated over large parts of the central european basin using a combination of high resolution cyclic stratigraphy and gamma ray logging on the basis of this robust lithostratigraphic framework a very precise positioning and correlation of paleomagnetic results has been realized eight outcrops and one completely cored well were collected yielding a total of 900 paleomagnetic samples from about 80 of them a characteristic remanence was obtained the consistent correlation of lithostratigraphic units and magnetozones supports an early acquisition of the characteristic magnetizations in both the magnetite bearing gray lithologies as well as the hematite bearing red brown lithologies the inter section correlation of all investigated profiles allows the creation of a well defined composite magnetic polarity scale the uppermost zechstein comprises one normal znz and two reversed zry zrz magnetozones in the overlying lower buntsandstein are delineated three normal sn1 to sn3 and three reversed sr1 to sr3 well documented magnetozones which can be correlated with magnetic records from the boreal and tethyan realms the combination of magnetostratigraphic and biostratigraphic data suggests the base of the oolite alpha 2 within the beds of the so called graubankbereich lower buntsandstein as the position of the hindeodus parvus calibrated permian triassic boundary within the germanic trias it is situated within the lowermost part of a remarkable thick normal magnetozone sn1 which is a distinctive feature occurring in virtually all magnetic records across the permian triassic boundary

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

ostracoda and dysaerobia in the lower jurassic of wales the reconstruction of past oxygen levels abstract the ostracoda are a subclass of small crustacea which inhabit most aquatic environments they have been recorded from the cambrian through to the recent the biology of one group of marine ostracoda the platycopina triassic recent enables them to better withstand decreased levels of dissolved oxygen in their immediate environment than other ostracods study of a number of geological sections has already shown that this suborder often dominates stratigraphical intervals which are considered to be representative of dysaerobic conditions in the light of this work the changing faunal composition of the lower jurassic of the mochras borehole wales is interpreted as a series of environmental changes which include fluctuating oxygen levels the degree of dysaerobia is assessed and its effect on the rate of faunal turnover is discussed

survival brachiopod faunas of the end permian mass extinction from the southern alps italy and south china eight brachiopod species in seven genera are described from the permian triassic boundary beds of south china and northern italy the brachiopods from northern italy are described for the first time and include two new species orbicoelia dolomitensis chen and spirigerella teseroi chen the permian affinity of these brachiopods and their stratigraphical position above the extinction horizon demonstrate that they are survivors from the end permian mass extinction the surviving brachiopods from south china which was located at the eastern margin of the palaeo tethys ocean are considerably abundant and diverse and are dominated by geographically widespread generalist elements adapted to a wide variety of environments they were mostly limited to the upper permian to lowest griesbachian in contrast the survivors in northern italy which was situated at the western margin of the palaeo tethys comprise elements ranging from the carboniferous to permian or widespread tethyan genera these survivors did not occur in the pre extinction western tethyan oceans but migrated into this region after the end permian extinction event disaster taxon lingula proliferated slightly earlier in western tethyan oceans than in eastern tethyan regions following the event survival brachiopods from both regions appear to have a generic affinity although they do not share any species both south chinese and italian survival faunas support the view that the survival interval is the duration when survivors are dominated by geographically widespread generalist organisms adapted to a wide variety of ecological conditions

conodont biostratigraphy across the permian triassic boundary at chaotian in northern sichuan china abstract detailed conodont biostratigraphy of the permian triassic boundary ptb interval was analyzed at the fossiliferous chaotian section in northern sichuan china the ptb interval at chaotian is composed of the uppermost permian mudstone limestone of the dalong formation and the lowermost triassic marl limestone of the feixianguan formation both representing deep basinal facies the ptb interval is enriched in ammonoids and conodonts and is divided into 6 conodont zones including 1 clarkina changxingensis changxingensis c subcarinata assemblage zone 2 c postwangi c sp b assemblage zone 3 c taylorae c zhejiangensis c changxingensis yini assemblage zone 4 barren intra zone 5 hindeodus parvus zone and 6 isarcicella zone in ascending order the first four zones correspond to the changhsingian whereas the latter two to the lower induan griesbachian the first occurrence fo of h parvus in the lowermost feixianguan formation is regarded as the conodont biostratigraphic boundary from the uppermost dalong formation various taxa of the genus clarkina occurred abundantly and suddenly disappeared at the top of the dalong formation therefore the top of the dalong formation is interpreted as a horizon of the eventostratigraphic boundary on the basis of conodont zones the chaotian section is correlated with the shangsi and meishan gssp of the ptb sections in south china and the zal section in iran

the terminal paleozoic fungal event evidence of terrestrial ecosystem destabilization and collapse because of its prominent role in global biomass storage land vegetation is the most obvious biota to be investigated for records of dramatic ecologic crisis in earth history there is accumulating evidence that throughout the world sedimentary organic matter preserved in latest permian deposits is characterized by unparalleled abundances of fungal remains irrespective of depositional environment marine lacustrine fluviatile floral provinciality and climatic zonation this fungal event can be considered to reflect excessive dieback of arboreous vegetation effecting destabilization and subsequent collapse of terrestrial ecosystems with concomitant loss of standing biomass such a scenario is in harmony with predictions that the permian triassic ecologic crisis was triggered by the effects of severe changes in atmospheric chemistry arising from the rapid eruption of the siberian traps flood basalts

a temporal link between the emeishan large igneous province sw china and the end guadalupian mass extinction abstract previous studies have suggested that there were two mass extinction events in the late permian one that occurred at the permo triassic p t boundary 251 ma and a second smaller mass extinction that occurred 5 8 myr earlier at the end of the guadalupian many workers have argued that there is a causal relationship between large scale volcanic activity and mass extinctions the major mass extinction event at the p t boundary coincides with the outpouring of huge quantities of lava that formed the siberian flood basalt province in russia courtillot et al earth planet sci lett 166 1999 177 195 and wignall earth sci rev 53 2001 1 33 suggested that the earlier late permian mass extinction coincided with the eruption of the lavas that formed the emeishan flood basalt efb province in sw china however the age of eruption of the efb lavas is poorly constrained using the sensitive high resolution ion microprobe to analyze zircons we have established the age of the xinjie intrusion believed to be a feeder to the main phase of efb volcanism to be 259 3 ma hence the formation of the efb is coincident with a proposed extinction event at 256 259 ma this result supports a temporal link between the emeishan large igneous province and the end guadalupian mass extinction

illawarra reversal the fingerprint of a superplume that triggered pangean breakup and the end guadalupian permian mass extinction abstract the permian magnetostratigraphic record demonstrates that a remarkable change in geomagnetism occurred in the late guadalupian middle permian ca 265 ma from the long term stable kiaman reverse superchron throughout the late carboniferous and early middle permian to the permian triassic mixed superchron with frequent polarity changes in the late permian and triassic this unique episode called the illawarra reversal probably reflects a significant change in the geodynamo in the outer core of the planet after a 50 million years of stable geomagnetism the illawarra reversal was likely led by the appearance of a thermal instability at the 2900 km deep core mantle boundary in connection with mantle superplume activity the illawarra reversal and the guadalupian lopingian boundary event record the significant transition processes from the paleozoic to mesozoic modern world one of the major global environmental changes in the phanerozoic occurred almost simultaneously in the latest guadalupian as recorded in 1 mass extinction 2 ocean redox change 3 sharp isotopic excursions c and sr 4 sea level drop and 5 plume related volcanism in addition to the claimed possible links between the above listed environmental changes and mantle superplume activity i propose here an extra explanation that a change in the core s geodynamo may have played an important role in determining the course of the earth s surface climate and biotic extinction evolution when a superplume is launched from the core mantle boundary the resultant thermal instability makes the geodynamo s dipole of the outer core unstable and lowers the geomagnetic intensity being modulated by the geo and heliomagnetism the galactic cosmic ray flux into the earth s atmosphere changes with time the more cosmic rays penetrate through the atmosphere the more clouds develop to increase the albedo thus enhancing cooling of the earth s surface the illawarra reversal the kamura cooling event and other unique geologic phenomena in the late guadalupian are all concordantly explained as consequences of the superplume activity that initially triggered the breakup of pangea the secular change in cosmic radiation may explain not only the extinction related global climatic changes in the end guadalupian but also the long term global warming cooling trend in earth s history in terms of cloud coverage over the planet

late permian continental sediments in the se iberian ranges eastern spain petrological and mineralogical characteristics and palaeoenvironmental significance abstract a detailed mineralogical and petrological study and the analysis of paleosol profiles in continental alluvial sediments of the late permian in the se iberian ranges spain allow us to infer the significant environmental changes that occurred during this time period three parts have been distinguished in the late permian sediments alcotas formation the lower part includes abundant and well preserved carbonate paleosol profiles and fine grained sediments made up by quartz feldspar hematite and illite with scarce kaolinite the preservation of dolomicrite in some paleosols suggests that they originally developed as dolocretes in an arid to semi arid climate with marked seasonality a change towards more humid and acid conditions can be deduced from the presence of siderite and goethite in paleosols in the middle part of the alcotas formation moreover the presence of plant remains coal beds and or carbonaceous shales at the top of the middle part and the lack of carbonate paleosols in the upper part of the formation would indicate a further step towards acid conditions these conditions would increase until the early triassic as indicated by the lack of carbonates and the presence of sr rich aluminium phosphate sulphates aps minerals at the base of the triassic canizar formation which clearly indicates extreme acid conditions during the permian triassic transition of the study area

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

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

mass extinctions and sea level changes abstract review of sea level changes during the big five mass extinctions and several lesser extinction events reveals that the majority coincide with large eustatic inflexions the degree of certainty with which these eustatic oscillations are known varies considerably thus the late ordovician and end cretaceous extinctions are associated with unequivocal major regressions demonstrated from numerous widespread regions in contrast the multiple high frequency sea level changes reported for the frasnian famennian crisis based on the supposed depth preferences of conodont taxa have little support from sequence stratigraphic analyses which reveals the interval to be one of highstand the end permian mass extinction has long been related to a severe first order lowstand of sea level newell n d 1967 revolutions in the history of life geol soc am spec pap 89 63 91 based primarily on the widespread absence of latest permian ammonoid markers but field evidence reveals that the interval coincides with a major transgression newell s hypothesis that marine extinctions are related to shelf habitat loss during severe regression remains tenable for the end guadalupian and end triassic extinction events but not for other crises rapid high amplitude regressive transgressive couplets are the most frequently observed eustatic changes at times of mass extinction with the majority of extinctions occurring during the transgressive pulse when anoxic bottom waters often became extensive the ultimate cause of the sea level changes is generally unclear a glacioeustatic driving mechanism can only be convincingly demonstrated for the end ordovician and end devonian events at other times it is speculated that they may relate to the widespread regional doming and subsequent collapse caused by the impingement of superplumes and ultimate eruption on the base of the lithosphere

periodicity in extinction and the problem of catastrophism in the history of life the hypothesis that extinction events have recurred periodically over the last quarter billion years is greatly strengthened by new data on the stratigraphic ranges of marine animal genera in the interval from the permian to recent these data encompass some 13 000 generic extinctions providing a more sensitive indicator of species level extinctions than previously used familial data extinction time series computed from the generic data display nine strong peaks that are nearly uniformly spaced at 26 ma intervals over the last 270 ma most of these peaks correspond to extinction events recognized in more detailed if limited biostratigraphic studies these new data weaken or negate most arguments against periodicity which have involved criticisms of the taxonomic data base sampling intervals chronometric time scales and statistical methods used in previous analyses the criticisms are reviewed in some detail and various new calculations and simulations including one assessing the effects of paraphyletic taxa are presented although the new data strengthen the case for periodicity they offer little new insight into the driving mechanism behind the pattern however they do suggest that many of the periodic events may not have been catastrophic occurring instead over several stratigraphic stages or substages

relationships between carbon isotope evolution and variation of microbes during the permian triassic transition at meishan section south china this paper investigates kerogen carbon isotopes the difference between carbonate and kerogen carbon isotopes 13ccarb kero 13ccarb 13ckero and the difference between carbonate and n c19 alkane compound specific carbon isotopes 13ccarb n c19 13ccarb 13cn c19 during the permian triassic transition at meishan south china the results show that kerogen carbon isotopes underwent both gradual and sharp shifts in beds 23 25 and 26 29 respectively the differences between carbonate and organic carbon isotopes both the 13ccarb kero and 13ccarb n c19 which are mainly affected by co2 fixing enzyme and pco2 oscillated frequently during the permian triassic transition both the variations of 13ccarb n c19 and 13ccarb kero coupled with the alternation between cyanobacteria and green sulfur bacteria indicated by biomarkers the episodic low values of 13ccarb n c19 corresponded to episodic blooms of green sulfur bacteria while the episodic high values of 13ccarb n c19 corresponded to episodic blooms of cyanobacteria the relationships between the variation of carbon isotopes and biota show that the microbes which flourished after the extinction of macroorganism affected the carbon isotope fractionation greatly combining the carbon isotope compositions and the pattern of size variation of the conodont neogondolella this paper supposes that anoxia of the photic zone at bed 24 was episodic and it would be caused by the degradation of terrigenous organic matters by sulfate reducing bacteria in the upper water column considered together with results from previous research the high resolution variation of the biogeochemistry presents the sequence of the important geo events during the permian triassic crisis

palaeomagnetism and magnetostratigraphy of the permian triassic northwest central siberian trap basalts abstract a detailed palaeomagnetic and magnetostratigraphic study of the permian triassic siberian trap basalts stb in the noril sk and abagalakh regions in northwest central siberia is presented thermal th and alternating field af demagnetisation techniques have been used and yielded characteristic magnetisation directions the natural remanent magnetisation of both surface and subsurface samples is characterised by a single component in most cases occasionally a viscous overprint can be identified which is easily removed by th or af demagnetisation the resulting average mean direction after tectonic correction for the 95 flows sampled in outcrops is d 93 7 i 74 7 with k 19 and 95 3 3 the corresponding pole position is 56 2 n 146 0 e unoriented samples from four boreholes cores in the same regions have also been studied they confirm the reversed normal succession found in outcrops the fact that only one reversal of the earth s magnetic field has been recorded in the traps can be taken as evidence for a rather short time span for the major eruptive episode in this region however there is evidence elsewhere that the whole volcanic activity associated with the emplacement of the stb was much longer and lasted several million years

survival strategies of brachiopod faunas from the end permian mass extinction abstract global reviews reveal that 102 brachiopod species including 40 indeterminate species belonging to 43 genera within 27 families survived the end permian mass extinction in south china the himalayan regions southern tibet nepal salt range and kashmir southern alps italy arctic canada western usa and western australia of these the surviving brachiopods are most abundant and widespread in south china where they occur in 32 of the 42 permian triassic p t boundary sections around the world brachiopod faunas are the most abundant and diverse post extinction survivors and their appearance above the end permian mass extinction horizon somewhat masks recognition of the end permian extinction these surviving brachiopods occur in three stratal intervals corresponding to the mixed fauna beds mfb hereafter 1 3 of the p t boundary beds a sharp drop in diversity of the brachiopod faunas coincides with the widely accepted end permian mass extinction horizon the post extinction brachiopods were also affected by a subsequent crisis corresponding to the boundary between mfb 2 and mfb 3 so that most survivors were extinct approximately 0 7 ma after the end permian mass extinction the surviving brachiopods were mainly productida followed by spiriferida in particular small chonetids chonetid like productellids and smooth thin shelled ambocollid spiriferids are most abundant lingula is extraordinarily abundant and widespread approximately 0 7 ma after the greatest extinction when many regions became devoid of articulate brachiopods widespread broadly adapted and small sized taxa preferentially survived frequent intrageneric speciation of widespread widely adapted generalist genera enabled survival brachiopods to occupy rapidly and efficiently vacant ecospace in the aftermath of the end permian extinction the ecological habitats of the post extinction brachiopods are subdivided into nearshore epeiric sea restricted carbonate platform open carbonate platform ramp and outer shelf environments of these the survival brachiopods are most diverse in the open platform environments the nearshore zone provided ideal habitats for the nonarticulated brachiopods to occupy whereas the survivors in the outer shelf are predominantly chonetids and chonetid like productellids the most successful survivors the productid brachiopods are widely distributed in six types of ecological habitats and thus have no apparent preference for specific environments the end permian extinction resulted in the movement of biogeographical provinces towards the palaeo equator the brachiopods survived mostly in the palaeo equatorial provinces and along the southern margins of the palaeo tethys ocean

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

early triassic conchostracans crustacea branchiopoda from the terrestrial permian triassic boundary sections in the moscow syncline abstract the permian triassic boundary marks the greatest mass extinction in earth s history in order to understand the real causes of this severe extinction event multidisciplinary investigations around the globe are required here the terrestrial permian triassic boundary sections in the vladimir region central russia were sampled bed by bed for conchostracan study in the early triassic intervals the following taxa were recognized for the first time cornia germari beyrich 1857 euestheria gutta lutkevitch 1937 magniestheria mangaliensis jones 1862 palaeolimnadiopsis vilujensis varentsov 1955 and rossolimnadiopsis novozhilov 1958 the wide distribution of c germari demonstrates their high value for biostratigraphy since this species was also reported from the lower buntsandstein subgroup in the germanic basin as well as from early triassic deposits in hungary greenland and siberia the assumption of an early triassic age of the studied sections is also supported by associated tupilakosaurus bone fragments which point to the tupilakosaurus wetlugensis zone in the earliest triassic

massive volcanism at the permian triassic boundary and its impact on the isotopic composition of the ocean and atmosphere abstract bulk carbonate and conodonts from three permian triassic p t boundary sections at guryul ravine kashmir abadeh central iran and pufels bula bulla italy were investigated for 13 c and 18 o carbon isotope data highlight environmental changes across the p t boundary and show the following features 1 a gradual decrease of 4 to more than 7 starting in the late permian changhsingian c bachmanni zone with two superimposed transient positive excursions in the c meishanensis h praeparvus and the m ultima s mostleri zones 2 two 13 c minima the first at the p t boundary and a higher occasionally double minimum in the lower i isarcica zone it is unlikely that the short lived phenomena such as a breakdown in biological productivity due to catastrophic mass extinction a sudden release of oceanic methane hydrates or meteorite impact s could have been the main control on the latest permian carbon isotope curve because of its prolonged 0 5 ma duration gradual decrease and the existence of a 1 positive shift at the main extinction horizon the p t boundary 13 c trend matches in time and magnitude the eruption of the siberian traps and other contemporaneous volcanism suggesting that volcanogenic effects such as outgassed co 2 from volcanism and even more thermal metamorphism of organic rich sediments as the likely cause of the negative trend

the permian triassic boundary in the continental series of eurasia abstract the most important eurasian sections where the transitional permian triassic boundary beds are characterized palaeontologically are found in the germanic basin west european platform moscow basin east european platform tungusska basin siberian platform jimsar basin dalongkou area tianshan mountains and noyan somon depression mongolia usually the permian and triassic continental formations formed under distinct palaeogeographic especially climatic and palaeotectonic conditions so the lithological and sedimentological differences between them are pronounced difficult problems appear in those regions where the sedimentation at this level proceeded under very similar conditions tungusska basin jimsar basin across the permo triassic boundary ptb among palaeontological data the most important for correlation of these continental beds is the tetrapod fauna broad interchange between the tetrapod fauna of the old world continents resulted in the wide distribution during the late permian and early triassic of common or closely related forms which enables distant correlations the ptb is marked by the change of the late permian tetrapod communities dominated by the large herbivore dicynodon or closely allied forms to assemblages that include lystrosaurus as the most common form this is recorded in lower triassic beds of eastern europe china mongolia india and siberia the upper permian sporomorph associations sa are dominated by striate bissacate pollen whereas the early lower triassic ones are distinguished by the very important role of spores primarily by cavate trilete lundbladispora densoisporites and also by non striate dissacate klausipollenites and teniate pollen lunatisporites in the oldest horizons of the triassic very distinctive species of conchostracans falsisca eotriassica kozur or the closely related form f verhojanica molin appear the ptb is within a normal polarity zone formerly considered the lowest palaeomagnetic zone of the triassic the boundary beds of two sections moscow basin and jimsar basin may be equally worthy as candidates for the ptb gssp in the continental series the preference should be given to the section better characterized and internationally accessible to scientists the ptb generally accepted for the continental series coincides more or less with the base of the otoceras concavum ammonite zone of the boreal province and with the base of the boundary clay in tethys at the same time it lies clearly below the traditionally adopted ptb in marine sequences at the base of the otoceras woodwardi zone and also below the first appearance datum fad of i parva in the meishan section proposed now as the ptb gssp yin 1996 the palaeozoic mesozoic boundary candidate of global stratotype section and point of the permian triassic boundary china university geoscience press wuhan 137 pp this demonstrates that the fad of i parva can be asynchronous see baud 1996 albertiana 18 pp 6 9 that is why in the choice of the ptb gssp in the marine series it is necessary to take into consideration the generally accepted point of view on the position of ptb in the continental series

heterogeneous volcanism across the permian triassic boundary in south china and implications for the latest permian mass extinction new evidence from volcanic ash layers in the lower yangtze region abstract volcanism has been suggested to have occurred widely in south china across the permian triassic boundary ptb this has important implications for understanding the cause of the latest permian mass extinction lmpe however few volcanic deposits have been reported in the lower yangtze region and the extent of volcanism is uncertain herein we report new discoveries of intensive volcanism in this region for the first time as evidenced by multiple n 20 and thick 3 5 cm claystones volcanic ash layers k bentonite found in three deep water outcrops in xuancheng city southern anhui province detailed petrographic and geochemical analyses of the ash layers were conducted to understand their origin and implications for the cause of the lpme including x ray diffraction scanning electronic microscopy energy dispersive spectroscopy and whole rock geochemistry the petrological and mineralogical results show that the claystones contain clastic minerals indicative of a volcanic origin such as zircon analcites pentagonal dodecahedral pyrite and micro spherules the whole rock geochemical data of the claystones suggest that the source rock of the ash layers was intermediate acidic rhyodacite the claystones are different from previously known claystones in the middle upper yangtze regions indicating the occurrence of chemically heterogeneous volcanism in south china at the ptb

anoxia as a cause of the permian triassic mass extinction facies evidence from northern italy and the western united states facies faunal and geochemical evidence from the permian triassic boundary sediments of the dolomites and idaho indicates a major anoxic event in the earliest triassic in both regions the basal beds consist of finely laminated micrites with common syngenetic pyrite the only fauna consists of occasional bedding plane assemblages of lingula or clacaria a typical lower dysaerobic assemblage this is a level where previous studies have shown a major negative carbon isotope excursion and a cerium anomaly in the dolomites the pyritic micrite directly overlies strata containing a diverse and typically permian marine fauna of algae foraminifers including fusulinids and articulate brachiopods implying an abrupt extinction in contradiction to many previous views sequence stratigraphic analysis of the dolomite boundary sediments reveals a minor sequence boundary in the late permian followed by extremely rapid transgression leading to the development of the relatively deep water pyritic micrite a maximum flooding surface at the permo triassic boundary a further pulsed deepening in the lower griesbachian recorded in both the dolomites and idaho lead to the widespread establishment of dysaerobic facies it is clear that most of the extinctions occurred at the erathem boundary although the subsequent failure of the marine benthos to fill the empty ecospace in the ensuing griesbachian may have been due to the widespread development of dysaerobic conditions

the biostratigraphic importance of conchostracans in the continental triassic of the northern hemisphere conchostracans or clam shrimp order conchostraca sars are arthropods with a carapace consisting of two chitinous lateral valves triassic conchostracans range in size from 2 to 12 5 mm long and are common in deposits that formed in fresh water lakes isolated ponds and brackish areas their dessication and freeze resistant eggs can be dispersed by wind over long distances therefore many conchostracan species are distributed throughout the entire north ern hemisphere in the late permian to middle triassic interval several of these forms are also found in gondwana many wide ranging conchostracan species have short stratigraphic ranges making them excellent guide forms for subdivision of triassic time and for long range correlations the stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits this makes con chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits upper triassic gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere in the norian some slight provincialism can be observed even within the northern hemisphere for example the sevatian redondestheria seems to be restricted to north america and acadiestheriella n gen so far has been found only in the sevatian deposits from the fundy basin of southeastern canada here we establish a con chostracan zonation for the changhsingian late permian to hettangian early jurassic of the northernhemispherethat forthemostpart isverywellcorrelatedwiththemarinescale thiszona tion is especially robust for the changhsingian to early anisian late ladinian to cordevolian and rhaetian to hettangian intervals for most of the middle and upper triassic this zonation is still preliminary five new genera six new species and a new subspecies of conchostracans are described that are stratigraphically important half of the eight stage boundaries of the triassic have been defined by a bio event within a marine global stratotype and point gssp locality and these definitions have been accepted by both the international subcommission on triassic stratigra phy and the international commission on stratigra phy the remaining four stage boundaries are nearing final definition in the lower triassic both the base of the induan priority brahmanian stage base of triassic and the base of the next younger olenekian stage have been firmly defined in the middle triassic there is wide agree ment that the defining species for the base of the anisian stage should be chiosella timorensis in the gssp candidate site at desli caira romania but there has not yet been a formal vote on this the base of the overlying ladinian stage however has been firmly defined in the upper triassic the base of the carnian has been firmly likewise defined but there is not yet a final defi nition for the boundaries of the overlying norian and rhaetian stages a consensus has not been reached on a defining species for the base of the norian or its gssp locality but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval for the base of the rhaetian misikella posthernsteini kozur mock has been chosen as the defining species by the international working group on the rhaetian stage and the gssp candidate locality at steinbergkogel austria has been studied in detail by a group under the leadership of l krystyn vienna and presented to the participants of the international conference on upper triassic sub divisions zonations and events in bad goisern in the autumn of 2008 the base of the overlying hettangian stage base of the jurassic has been defined so far only by a working group as the fad first appearance datum of psiloceras spelae guex taylor rakus bucher the final definition of the triassic stages within marine gssp sections will be completed in the near future but more than 50 of known triassic rocks are of continental origin therefore the main task of triassic stratigraphers in thefuture will besubdivid ing and correlating terrestrial strata both between

implications for the history of cenozoic opal deposition from a quantitative model in addition to being a time of enhanced crustal activity and a warmer climate the eocene also saw prolonged periods of silica accumulation on the ocean floor the peak of this accumulation occurred at approximately 50 ma creating horizon ac a layer of silica rich sediments spanning approximately 4 my horizon ac is comparatively isolated in time from known silicic acid addition processes leading mcgowran 1989 mcgowran b 1989 silica burp in the eocene ocean geology 17 pp 857 860 to suggest a novel mechanism the silica burp hypothesis that centres on the temporal decoupling of silicic acid supply and burial by climatic variation here we examine this hypothesis using a quantitative biogeochemical model of the silicon cycle our results unequivocally show that mcgowran s hypothesis is unable to account for horizon ac the model s residence time and ocean capacity for silicic acid are insufficient to permit the degree of temporal decoupling proposed by mcgowran inverting the model s results suggests that instead the sediment record may be a useful proxy for silicic acid additions to the ocean

the use of ostracoda to reconstruct the oxygen levels of late palaeozoic oceans abstract it has been recently demonstrated that in post palaeozoic and modern oceans filter feeding ostracods totally dominate over deposit feeders during times of dysaerobia in modern oceans the filter feeding platycopida the sole extant group with this feeding strategy in terms of abundance completely dominate the oxygen minimum zone despite occurring there in low specific diversity the percentage of filter feeders has been used previously to locate kenoxic events and to determine palaeoxygen levels in liassic cenomanian and palaeogene oceans the term kenoxic is used to denote an event when oxygen levels were reduced most so called anoxic events which for the name implies total deprivation of oxygen were in fact kenoxic a kenoxic event produces dysaerobic rather than anaerobic conditions in the present paper upper palaeozoic ostracoda are analysed and it is concluded that the palaeocopida metacopina platycopina kloedenellacea and the paraparchitacea were filter feeders filter feeders were therefore much more diverse in the palaeozoic than subsequently in the palaeopsychrosphere all ostracods even podocopids acquired peculiar adaptations to allow them to live in the oxygen minimum zone using the percentage of filter feeding ostracod species of shelf seas as a guide relative oxygen levels for the seas which deposited the carbonate platforms of northwest europe during the emsian to visean interval are calculated changes in oceanic oxygen are related to global climatic changes especially in temperature and are therefore important in any considerations of palaeoclimatology our reconstructions for both dissolved oxygen and sea water temperatures from the late early devonian to the early carboniferous based upon the percentage of filter feeding species clearly depict the late devonian events as a time of low oxygen high temperatures and high filter feeders into the frasnian there was a subsequent cooling and improved oxygenation into the famennian and a glacial maximum marked by a low percentage of filter feeders in the lower tournaisian this was followed by a slight increase in the percentage of filter feeders into the visean a signal of lower levels of oxygen but continuing in a contrasted climate a model which yields reference points giving absolute values of oxygen is proposed for late palaeozoic benthic marine environments

growth and demise of permian biogenic chert along northwest pangea evidence for end permian collapse of thermohaline circulation abstract the permian chert event pce was a 30 ma long episode of unusual chert accumulation along the northwest margin of pangea and possibly worldwide the onset of the pce occurred at about the sakmarian artinskian boundary in the sverdrup basin canadian arctic where it coincides with a maximum flooding event the ending of high frequency high amplitude shelf cyclicity the onset of massive biogenic chert deposition in deep water distal areas and a long term shift from warm to cool water carbonate sedimentation in shallow water proximal areas a similar and coeval shift is observed from the barents sea to the northwestern usa a landward and southward expansion of silica factories occurred during the middle and late permian at which time warm water carbonate producers disappeared completely from the northwest margin of pangea biotically impoverished and increasingly narrow cold water carbonate factories characterised by non cemented bioclasts of sponges bryozoans echinoderms and brachiopods were then progressively replaced by silica factories by late permian time little carbonate sediments accumulated in the barents sea and in the sverdrup basin where the deep to shallow water sedimentary spectrum was occupied by siliceous sponge spicules by that time biogenic silica sedimentation was common throughout the world silica factories collapsed in the late permian abruptly bringing the pce to an end in northwest pangea the end permian collapse of the pce was associated with a major transgression and with a return to much warmer oceanic and continental climatic conditions chert deposition resumed in the distal oceanic areas during the early middle triassic anisian after a 8 10 ma interruption early triassic chert gap the conditions necessary for the onset expansion and zenith of the pce were provided by the thermohaline circulation of nutrient rich cold waters along the northwestern and western margin of pangea and possibly throughout the world oceans these conditions provided an efficient transportation mechanism that constantly replenished the supply of silica in the area created a nutrient and oxygen rich environment favouring siliceous biogenic productivity established cold sea floor conditions hindering silica dissolution while increasing calcium carbonate solubility and provided conditions adverse to organic and inorganic carbonate production the northwest margin of pangea was for nearly 30 ma bathed by cold waters presumably derived from the seasonal melting of northern sea ice the assumed engine for thermohaline circulation this process started near the sakmarian artinskian boundary intensified throughout middle and late permian time and ceased suddenly in latest permian time it led to oceanic conditions much colder than normally expected from the palaeolatitudes and the influence of cold northerly derived water was felt as far south southern nevada the demise of silica factories was caused by the rapid breakdown of these conditions and the establishment of a much warmer marine environment accompanied by sluggish circulation and perhaps a reduced input of dissolved silica to the ocean complete thawing of northern sea ice would have ended thermohaline circulation and led to warm and sluggish oceanic conditions inimical to the production accumulation and preservation of biogenic silica

comparative probabilistic assessment of the hydrological performance of reconstructed and natural watersheds the oil sands industry has committed to returning the mine sites to a productive condition the reconstructed soil covers must have sufficient available water holding capacity awhc to supply enough moisture over the growing season to promote vegetation in order to assess the sustainability of various soil cover alternatives a generic system dynamic watershed model entitled gsdw was used along with the available historical meteorological records to estimate the maximum soil moisture deficit and annual evapotranspiration fluxes a probabilistic framework was adopted consequently frequency curves of the maximum annual moisture deficit values are constructed and used to assess the probability that various reconstructed and natural watersheds can provide the associated moisture demands in general the study showed a tendency for the reconstructed watershed to provide less moisture for evapotranspiration than natural systems watersheds of various soil types layering thicknesses and topography were studied the gained knowledge was used to predict the possible performance of a hypothetical reclamation cover the results indicated that the hypothetical cover performed in a similar manner to the thickest existing soil cover which confirmed a high probability of that cover to survive under the same existing climatic conditions moreover this probabilistic framework was found to be useful for integrating information gained from natural watersheds e g the canopy of mature natural systems and transfer the results to the reconstructed system the results show that the canopy influenced the moisture deficit regime positively which signifies a greater possibility that reconstructed covers will adapt to vegetation type in brief the adopted approach enables better understanding of the response of reconstructed systems via multiple simulations of what if scenarios using different soil vegetation alternatives copyright 2010 john wiley sons ltd

some aspects of the permian triassic boundary ptb and of the possible causes for the biotic crisis around this boundary abstract the first appearance datum fad of hindeodus parvus is an excellent datum very close to the base of the otoceras woodwardi zone priority base of the triassic for the first time it allows an exact correlation of the ptb in all marine facies and faunal realms the following features of the extinction and recovery patterns near the ptb are most important for the search for causes of the ptb biotic crisis 1 most strongly affected were the siliceous plankton radiolarians and the warm water benthos and nekton 2 most of the cold water faunas were not significantly affected 3 the recovery of the warm water benthos and siliceous plankton occurred only after an unusually long time during the late olenekian and middle triassic 4 the productivity of the terrestrial plants dropped strongly and the recovery was mainly in the upper olenekian and in the middle triassic 5 several terrestrial extinction events occurred at different levels within the upper permian considerable before the marine ptb at or close to the fad of lystrosaurus no extinction event in the terrestrial faunas can be observed 6 terrestrial faunal elements that survived the dzhulfian dorashamian extinctions were able to survive some months of extreme climatic conditions by hibernation like life stages vertebrates or by dry and freezing resistant eggs conchostracans 7 about 50 of the genera that disappeared at the ptb re appeared in the olenekian middle triassic interval lazarus taxa or in this time interval genera appeared that had undoubtedly evolved from genera that had disappeared at the ptb and 8 the ptb is preceded by mass occurrences of marine and continental fungi and the fungal spike ends abruptly a little before the ptb a scenario for the ptb biotic crisis is elaborated that takes into consideration the real not interpolated diversity patterns of different marine and continental fossil groups the exact correlation of bioevents in different faunal realms and facies the strong biotic crisis in the tethyan warm water faunas in contrast to the much weaker biotic event in cold water faunas the severe dzhulfian dorashamian climate in many parts of the world caused by the continent ocean configuration and by siberian trap volcanism the cooling of the boreal area by the northward drift of pangaea that interrupted the exchange of warm water benthos between the tethys and western north america during the guadalupian the extinction event at the guadalupian lopingian boundary that restricted most of the affected warm water faunas to the tethys the importance of lower scythian anoxia that reached an unusually shallow level and above all the effects of the contemporaneous huge volcanic events about 250 m y ago on the siberian platform and in the eastern tethys that caused a 3 6 months lasting volcanic winter with strong cooling in low latitudes followed by a strong global warming

permian strontium isotope stratigraphy cvu acknowledges funding from the leopoldina german national academy of sciences grant no lpds 2014 08

ostracods crustacea through permian triassic events abstract through geological times the main turnover of marine ostracod group occurred at the permian triassic boundary ptb when the palaeozoic world gave way to meso cenozoic world as quite all the groups ostracods intensively suffered of the end palaeozoic events but they have the particularity to pass the ptb and to be present in quite all marine environments we have studied the ostracod assemblages from the best preserved marine permian triassic sections through the world these sections are for most of them located along the palaeo tethys margins south china block and tibet r p china bukk mountains hungary dolomites italy taurus mountains turkey and elbourz mountains iran these areas present different environmental settings from very shallow water to deep shelf the biostratigraphy is well constrained by the presence of conodont index in deep environment from external shelf to slope all the permian ostracods disappear slightly before the ptb and are absent from the early triassic the last representatives of palaeopsychrospheric forms occur in the early anisian on the platforms during the late permian the ostracods are abundant and highly diversified everywhere along peri tethyan margins the typical palaeozoic forms are mixed with the very first meso cenozoic representatives the specific extinction rates in the latest permian vary from 74 to 100 during the earliest triassic two different settings have to be considered with or without microbialitic deposits the development of microbialites gives favorable ecological conditions to ostracods during the griesbachian the fauna is composed of both new comers and surviving palaeozoic forms the reduction of size is frequently observed this interval is called survival stage during the dienerian and the smithian the fauna are very scarce and poor these two substages represent the maximum of poverty for the ostracod fauna may be due to the development of anoxia on the platforms during the spathian occurs the beginning of the true recovery the very last palaeozoic representatives are found in the earliest anisian which is the radiation stage of ostracod fauna with typical new comers the interval of palaeozoic meso cenozoic ostracod turnover is quite long about 15 my

synchrony and causal relations between permian triassic boundary crises and siberian flood volcanism the permian triassic boundary records the most severe mass extinctions in earth9s history siberian flood volcanism the most profuse known such subaerial event produced 2 million to 3 million cubic kilometers of volcanic ejecta in approximately 1 million years or less analysis of 40 ar 39 ar data from two tuffs in southern china yielded a date of 250 0 0 2 million years ago for the permian triassic boundary which is comparable to the inception of main stage siberian flood volcanism at 250 0 0 3 million years ago volcanogenic sulfate aerosols and the dynamic effects of the siberian plume likely contributed to environmental extrema that led to the mass extinctions

transition into a hothouse world at the permian triassic boundary a model study abstract the permian triassic boundary ptb 252 3 ma marks the largest mass extinction of the phanerozoic with a loss of more than 90 of marine organisms and is characterized by lethally hot surface temperatures the ptb global warming has been linked to greenhouse gas emissions from the siberian traps and associated coal bed intrusions and likely led to severe environmental consequences such as ocean acidification a decline in the marine productivity and extensive hypoxia in order to understand these changes feedbacks in the climate system have been explored with sensitivity climate simulations and compared to temperature proxies from the sedimentary record the response of the ptb ocean circulation to an atmospheric perturbation of 5000 pg c comparable to earth s total fossil fuel inventory leads to a global temperature increase by 3 4 c and an increase in ocean stratification the pole to equator temperature gradient decreases by 2 c with an increase in co2 radiative forcing predominately due to snow albedo feedbacks over gondwana the greenhouse induced warming would have led to a weakening of the hadley cell and an associated decrease in the trade winds and equatorial primary productivity these climatic changes might have been amplified by cloud feedback processes a reduced concentration of cloud condensation nuclei due to a biologic decline of dimethylsulfide caused by the temperature stress or changes in airborne mineral particles could have reduced the cloud albedo particularly in high latitudes results from a climate simulation with reduced cloud albedo suggest a polar warming of up to 7 c and a reduction of the pole to equator temperature gradient by 4 c in addition to the reduction caused by the increase in greenhouse induced radiative forcing the scenario with reduced cloud albedo further leads to an increase in ocean stratification and widespread low oxygen concentrations in the panthalassa during the early triassic

fungal event and palynological record of ecological crisis and recovery across the permian triassic boundary the end of the permian period was marked by the most severe mass extinction in the geologic record detailed quantitative study of pollen and spores from shallow marine deposits spanning the permian triassic p tr boundary in israel reveals a sequence of palynological ecological stages reflecting a major crisis among land plants the disappearance of the gymnosperm dominated palynoflora of the late permian lueckisporites virkkiae zone is recorded at a claystone horizon containing almost exclusively abundant fungal remains and carbonized terrestrial plant debris this fungal spike is followed by a zone dominated by marine acritarchs and a succession showing ecological recovery with abundantlycopodsporesandeventualreappearanceofbisaccategymnospermpolleninthe earlytriassic thelatestpermianproliferationoffungiisrecognizableworldwideandcan be correlated with other paleontological and geochemical markers of a global ecological disaster

anomalous hopane distributions at the permian triassic boundary meishan china evidence for the end permian marine ecosystem collapse abstract molecular and carbon isotopic geochemistry of hopanes in marine sediments of the meishan section in changxing county zhejiang province of china were studied to reveal biotic and environmental changes across the permian triassic boundary ptb and the wuchiapingian changhsingian boundary wcb the hopane distribution at the ptb is characterized by high ratios of moretane hopane tm ts tm c 30 hopane c 31 c 32 hopane and hopane sterane this hopane distribution is anomalous for these marine sediments but it is typical of coal measure strata and soils two possible genetic mechanisms for such an anomaly are suggested 1 these hopanes were terrigenous and most probably originated from acidified soil and peat this mechanism implies that the marine primary production and aerobic bacteria production at the ptb were extremely low 2 this hopane distribution was possibly caused by freshening and acidification of the upper water column during the end permian to early triassic marine stagnation and stratification this hopane anomaly which coincides with the end permian mass extinction and carbon isotope excursion may signal the end permian mass extinctions and marine and terrigenous ecosystem collapse the 13 c enriched hopanes with the fingerprint of typical anoxic marine shales coupled with an n c 15 n c 17 dominated distribution of n alkanes strongly indicate that the organic matter around the wcb at meishan originated mainly from cyanobacteria the corresponding positive 13 c carbonate and higher total organic carbon and hydrocarbon index hi values strongly suggest that high marine primary production and marine anoxia caused by intermittent cyanobacterial blooms resulted in the local mass extinction at meishan

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

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

recurrent biotic rebounds during the early triassic biostratigraphy and temporal size variation of conodonts from the nanpanjiang basin south china eleven conodont zones are established for the lower triassic of the motianling section in the nanpanjiang basin south china detailed size measurements on 2244 p1 conodont elements demonstrate dynamic size variation patterns during the early triassic that are calibrated to the early triassic timescale and conodont zonation correlation of conodont size variation with various environmental indicators shows that these size changes are primarily controlled by rapidly changing and episodic environmental conditions and ecological recovery in the aftermath of the end permian mass extinction decreasing size trends occur in the early griesbachian late griesbachian and at the smithian spathian boundary episodes of size increase rebounds occur in the middle griesbachian induan olenekian boundary and middle late spathian the observed temporal size variations indicate that conodont animals were significantly affected by rapidly changing environmental conditions mainly temperature and redox conditions during the early triassic and recurrent size increases rebounds occurred during periods of environmental and climatic amelioration climatic cooling and oxygenation demonstrating a complicated recovery history of marine ecosystems in the aftermath of the largest phanerozoic biotic crisis supplementary material data for all species are available at https doi org 10 6084 m9 figshare c 4528616