the lilliput effect in the aftermath of the end permian extinction event early triassic animal body fossils and trace fossils are small relative to those in older and younger intervals size decreases sharply through the end permian extinction event and permian triassic boundary and the smallest sizes are encountered in the parvus and isarcica zones of the earliest induan animals appearing within these two zones are also exceedingly small compared to younger congenerics and conspecifics temporary dramatic size decrease of surviving taxa in the immediate aftermath of the extinction event is an example of the lilliput effect coined by urbanek a 1993 biotic crises in the history of upper silurian graptoloids a palaeobiological model historical biology 7 29 50 body size increases somewhat from the carinata zone mid induan but remains depressed for the duration of the early triassic and pre extinction sizes are not commonly recorded until at least the middle triassic marine and terrestrial faunas appear to be similarly affected the lilliput effect and longer term size reduction could be the result of several factors environmental parameters such as marine anoxia due to low atmospheric concentrations of oxygen at this time coupled with sluggish ocean circulation in a greenhouse world and food shortage are the likely proximal causes for the early triassic lilliput effect no single cause can explain all the observations and a combination of factors are likely to be involved

climate warming in the latest permian and the permian triassic mass extinction high resolution oxygen isotope records document the timing and magnitude of global warming across the permian triassic p tr boundary oxygen isotope ratios measured on phosphate bound oxygen in conodont apatite from the meishan and shangsi sections south china decrease by 2 in the latest permian translating into low latitude surface water warming of 8 c the oxygen isotope shift coincides with the negative shift in carbon isotope ratios of carbonates suggesting that the addition of isotopically light carbon to the ocean atmosphere system by siberian traps volcanism and related processes resulted in higher greenhouse gas levels and global warming the major temperature rise started immediately before the main extinction phase with maximum and harmful temperatures documented in the latest permian meishan bed 27 the coincidence of climate warming and the main pulse of extinction suggest that global warming was one of the causes of the collapse of the marine and terrestrial ecosystems in addition very warm climate conditions in the early triassic may have played a major role in the delayed recovery in the aftermath of the permian triassic crisis

changes in brachiopod body size prior to the early toarcian jurassic mass extinction abstract herein we analyze the shell length as estimation of the body size of several brachiopod assemblages recorded into the extinction interval prior to the early toarcian mass extinction they were collected from representative localities around the iberian massif spain and portugal presenting different paleoenvironmental conditions the analysis performed has revealed two different trends of spatial and temporal changes in body size 1 mean size decreases in the assemblages following an anticlockwise pattern from iberian to lusitanian basins in relation to the progressive environmental stress caused by shifts on terrigenous input and in depth this diminution results from changes in the relative abundance of bigger or smaller species in each area rather than from miniaturization of the taxa 2 some new evolved or more resilient species show increasing sizes over time along the extinction interval this increase affects both big spiriferinides in the iberian basin and small rhynchonellides and koninckinides in the lusitanian basin and runs in parallel to the drop in diversity and the progressive warming of the sea water in this interval in all the localities this increase in body size has been related to the changes in diversity that could have favored the access to resources for resilient or new evolved species the observed patterns are comparable with those detected in the end permian crisis and might indicate a generalizable response to similar biotic crises

anomalous early triassic sediment fluxes due to elevated weathering rates and their biological consequences analysis of 16 marine permian triassic boundary sections with a near global distribution demonstrates systematic changes in sediment fluxes and lithologies in the aftermath of the end permian crisis sections from continent margin and platform settings exhibit higher bulk accumulation rates bars and more clay rich compositions in the griesbachian earliest triassic relative to the changhsingian latest permian these patterns which largely transcend regional variations in tectonic setting sequence stratigraphic factors and facies are hypothesized to have resulted from a substantial average 7 increase in the flux of eroded material from adjacent land areas owing to accelerated rates of chemical and physical weathering as a function of higher surface temperatures increased acidity of precipitation and changes in landscape stability tied to destruction of terrestrial ecosystems this sediment surge may have been a contributory factor to the latest permian marine biotic crisis as well as to the delayed recovery of early triassic marine ecosystems owing to the harmful effects of siltation and eutrophication contemporaneous deep sea sections show no increases in sediment flux across the permian triassic boundary owing to their remoteness from continental siliciclastic sources and location below the paleo carbonate compensation depth

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

paleophysiology and end permian mass extinction physiological research aimed at understanding current global change provides a basis for evaluating selective survivorship associated with permo triassic mass extinction comparative physiology links paleontological and paleoenvironmental observations supporting the hypothesis that an end permian trigger most likely siberian trap volcanism touched off a set of physically linked perturbations that acted synergistically to disrupt the metabolisms of latest permian organisms global warming anoxia and toxic sulfide probably all contributed to end permian mass mortality but hypercapnia physiological effects of elevated pco2 best accounts for the selective survival of marine invertebrates paleophysiological perspectives further suggest that persistent or recurring hypercapnia global warmth also played a principal role in delayed triassic recovery more generally physiology provides an important way of paleobiological knowing in the age of earth system science 2007 elsevier b v all rights reserved

how and why did the lingulidae brachiopoda not only survive the end permian mass extinction but also thrive in its aftermath the end permian mass extinction devastated most of the organisms in the sea and on land however a few late permian taxa survived the mass extinction and also the subsequent early triassic post extinction catastrophic environments among them the lingulidae brachiopods were perhaps one of the most noted conquerors not only had they survived the mass extinction but also they thrived in the early triassic marine realm forming a nearly globally distributed lingulidae fauna characterized by low taxonomic diversity but high abundance of individuals the reasons that this group of brachiopods was able to achieve this remain unclear and could possibly include a number of interacting factors among them are their wide ecological adaptations and their shell composition and appearance the long term evolutionary trends in the shell microstructure and exterior of the lingulidae since the late devonian are thought to have advanced considerably by the end permian to the extent that the shells of the brachiopods were able to sustain stressful e g anoxic environments in addition a variety of short term adaptive changes in the shell size reducing shell size shape shells became more pointed and flatter anteriorly and thickness reducing shell thickness are believed to have also aided the survival of the brachiopods through the highly toxic marine environments from the latest permian to the early triassic the long term unchanged organophosphatic shell composition of lingulidae brachiopods is considered to be another key feature that must have aided the survival of this group in the end permian to the early triassic period for organophosphatic shell composition would have prevented the brachiopods from dissolution in the highly acidic marine environment prevailing globally during the permian triassic transition the ability that the lingulids had to live in a wide range of environmental conditions from high latitude to low latitude and from the shoreface to the relatively deep sea environments is also considered vital for the group to have managed to survive the catastrophic event in the latest permian and then thrive in the vacated ecological space in the ensuing early triassic disaster period 2007 elsevier b v all rights reserved

end permian mass extinction in the oceans an ancient analog for the twenty first century the greatest loss of biodiversity in the history of animal life occurred at the end of the permian period 252 million years ago this biotic catastrophe coincided with an interval of widespread ocean anoxia and the eruption of one of earth s largest continental flood basalt provinces the siberian traps volatile release from basaltic magma and sedimentary strata during emplacement of the siberian traps can account for most end permian paleontological and geochemical observations climate change and perhaps destruction of the ozone layer can explain extinctions on land whereas changes in ocean oxygen levels co2 ph and temperature can account for extinction selectivity across marine animals these emerging insights from geology geochemistry and paleobiology suggest that the end permian extinction may serve as an important ancient analog for twenty first century oceans

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

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

calcium isotope constraints on the end permian mass extinction the end permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope 13c composition of carbonate minerals several extinction scenarios consistent with these observations have been put forward secular variation in the calcium isotope 44 40ca composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction here we report 44 40ca across the permian triassic boundary from marine limestone in south china the 44 40ca exhibits a transient negative excursion of 0 3 over a few hundred thousand years or less which we interpret to reflect a change in the global 44 40ca composition of seawater co2 driven ocean acidification best explains the coincidence of the 44 40ca excursion with negative excursions in the 13c of carbonates and organic matter and the preferential extinction of heavily calcified marine animals calcium isotope constraints on carbon cycle calculations suggest that the average 13c of co2 released was heavier than 28 and more likely near 15 these values indicate a source containing substantial amounts of mantle or carbonate derived carbon collectively the results point toward siberian trap volcanism as the trigger of mass extinction

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

altered river morphology in south africa related to the permian triassic extinction the permian triassic transition in the karoo basin of south africa was characterized by a rapid and apparently basin wide change from meandering to braided river systems as evidenced by preserved sedimentary facies this radical changeover in river morphology is consistent with geomorphic consequences stemming from a rapid and major die off of rooted plant life in the basin evidence from correlative nonmarine strata elsewhere in the world containing fluvial permian triassic boundary sections suggests that a catastrophic terrestrial die off of vegetation was a global event producing a marked increase in sediment yield as well as contributing to the global 13 c excursion across the permian triassic boundary

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

global brachiopod palaeobiogeographical evolution from changhsingian late permian to rhaetian late triassic abstract previous studies suggest that the end permian mass extinction caused a dramatic drop of marine biodiversity near the permian triassic boundary however it is unclear how profoundly this severe extinction might have changed the global provincialism and how global provincialism responded to the protracted process of this extinction and subsequent recovery through the triassic in this paper we carried out quantitative time series analyses of global brachiopod palaeobiogeography over a timespan of nine consecutive stages substages from the latest permian changhsingian to the latest triassic rhaetian based on a global brachiopod database of 483 genera and 2459 species from 1425 localities our results suggest that the extinction resulted in a global biogeographical eclipse in the ensuing early triassic griesbachian and dienerian times in that neither biogeographic realm nor province could be recognized it was characterized by an extreme low diversity mostly dwarfed and nearly globally distributed brachiopod fauna coupled with persistently high sea surface temperature and a flattened global latitudinal thermal gradient global provincialization emerged again during the olenekian at province level and reached its peak stage during the carnian when three realms and six provinces were clearly recognized global provincialism became weakened again in the latest triassic rhaetian marked by three general realms but no province distinguished our analyses suggest that both palaeolatitude related thermal gradient and the presence of pangea a profound geographic barrier were most effective in explaining the spatial patterns in addition oceanic currents along the northwestern coast of pangea also played an important albeit regional role in linking southern north and central america brachiopod faunas with those of the boreal realm this study also revealed that the brachiopod biodiversity center moved northwards over the studied interval accompanied and hence accountable for by the northward drift of a large number of tectonic blocks in the palaeotethys and neotethys during the triassic

changes in size and growth rate of lilliput animals in the earliest triassic abstract marine invertebrate taxa that survived the late permian latest changhsingian mass extinction event are all much smaller than they were prior to the event an example of the lilliput effect new taxa that first appeared in the immediate extinction aftermath are also small compared to their size in younger strata the lilliput effect is a temporary phenomenon with most surviving taxa returning to pre extinction size in the first two conodont zones of the triassic in this study the growth rates of some of the early triassic lilliput animals estimated by growth line analysis were compared from different stratigraphic levels to determine how this variable fluctuated as body size returned to pre extinction values after the event specimens were collected from the mazzin and siusi members of the werfen formation in northern italy from facies deposited in a tropical mixed siliciclastic carbonate ramp setting measurements of the bivalves unionites and claraia the gastropod bellerophon and the brachiopod lingula were made in the field with subsequent growth line analysis conducted on well preserved specimens of lingula specimens collected from the basal triassic mazzin member were smaller than those from the younger siusi member growth line analysis indicates that the smaller mazzin member specimens had a greater number of more closely spaced growth lines than the larger siusi member specimens the small lilliput animals living in the immediate aftermath of the late permian event therefore suffered more interruptions to growth and had overall slower growth rates than larger individuals living in later recovery times frequent interruptions to growth and an overall slower growth rate in specimens from the hindeodus parvus and isarcicella isarcica zones of the mazzin member lower induan reflects suboptimal environmental conditions such as the frequency or severity of low oxygen episodes temperature extremes and or disruptions to primary productivity

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

reliability of multitaxon multiproxy reconstructions of environmental conditions from accretionary biogenic skeletons abstract evaluation and quantification of climate change require data on subseasonal to daily environmental extremes from those periods before instrumental records were available this study employs a high resolution multitaxon multiproxy approach and analyzes how faithfully accretionary biogenic skeletons record environmental extremes six specimens of two bivalve mollusks chione fluctifraga mytella guyanensi and one barnacle species chthamalus fissus from a single habitat northern gulf of california mexico were collected contemporaneous shell portions from these specimens were analyzed for shell growth rates sclerochronology and stable isotopes 18o 13c and were compared to instrumental records the results of these analyses included some significant observations first shell 18o values overestimate winter temperatures and underestimate summer temperatures second the actual diurnal temperature range is not recorded in the biogenic skeletons third skeletal growth is biased toward a

3d implicit modeling of the sishen mine new resolution of the geometry and origin of fe mineralization the sishen deposit is one of the largest iron ore concentrations in current production hematite mineralization occurs along a strike length of 14 km with a width of 3 2 km and a maximum vertical extent of 400 m below the original surface the 986 mt reserve incorporates a suite of individual orebodies beneath a locally preserved tectonized unconformity with a wide range of geometries depths and orientations fully constrained implicit 3d modeling of the entire mining volume 70 km3 was undertaken to the original pre mining topography the model incorporates 5287 mapping points and 21 000 drillholes and provides exceptional insight into the original configuration of ore and its relationship to contacts unconformities and structures in the enclosing country rock the bulk of ore occurs to the west of a strike extensive partially inverted normal fault sloep fault within an asymmetrical synclinal structure on its western flank this linear n s distribution of deep thick ore is punctuated by palaeosinkholes wherein base of ore dips of greater than 45 are concentrically arranged localized ore volumes also occur along faults and in fault bounded downthrown blocks to the north of nw se and ne sw trending strike slip faults that show relatively minor uplift to the south probably due to the lomanian namaqua natal orogeny the revised model demonstrates the proximity of ore to a tectonized unconformity and highlights the structural control on ore volumes implying that fe mineralization at sishen cannot be exclusively attributed to supergene enrichment and concentric palaeosinkhole formation

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

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

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

recovery pattern of brachiopods after the permian triassic crisis in south china in south china the changhsingian brachiopods are extraordinarily abundant and diverse comprising 468 species in 144 genera however approximately 91 of brachiopod species were eliminated during the permian triassic p tr mass extinction event brachiopods in the aftermath of the p tr mass extinction were extremely rare with only one opportunistic taxon lingulida occasionally found in the griesbachian and smithian at a high abundance species diversity of articulated brachiopods in the early griesbachian late griesbachian dienerian and smithian are 35 3 2 and 0 respectively although a few of mesozoic type species occurred in the griesbachian dienerian and smithian a marked diversification of brachiopods occurred in the spathian and early anisian and was characterised by 9 and 17 mesozoic type species respectively the diversification of brachiopods in the spathian and early anisian coincides with the contemporaneous expansion of the refuge zone suggesting that the improvement of marine environmental conditions e g lethally hot temperature and anoxic seawater played a key role in brachiopod recovery after the p tr mass extinction

erosional truncation of uppermost permian shallow marine carbonates and implications for permian triassic boundary events on shallow marine carbonate buildups in south china turkey and japan uppermost permian skeletal limestones are truncated by an erosional surface that exhibits as much as 10 cm of topography including overhanging relief sedimentary facies microfabrics carbon isotopes and cements together suggest that erosion occurred in a submarine setting moreover biostratigraphic data from south china demonstrate that the surface postdates the uppermost permian sequence boundary at the global stratotype section and truncates strata within the youngest known permian conodont zone the occurrences of similar truncation surfaces at the mass extinction horizon on carbonate platforms across the global tropics each overlain by microbial buildups and their association with a large negative excursion in 13 c further suggest a causal link between erosion of shallow marine carbonates and mass extinction previously proposed to account for marine extinctions the hypothesis of rapid carbon release from sedimentary reservoirs or the deep ocean can also explain the petrographic observations rapid unbuffered carbon release would cause submarine carbonate dissolution accounting for erosion of uppermost permian skeletal carbonates and would be followed by a pulse of high carbonate saturation explaining the precipitation of microbial limestones containing upwardgrowing carbonate crystal fans models for other carbon release events suggest that at least 5 10 18 g of carbon released in 100 k y would be required of previously hypothesized permian triassic boundary scenarios thermogenic methane production from heating of coals during siberian traps emplacement best accounts for petrographic characteristics and depositional environment of the truncation surface and overlying microbial limestone as well as an associated carbon isotope excursion and physiologically selective extinction in the marine realm

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

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

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

erosional truncation of uppermost permian shallow marine carbonates and implications for permian triassic boundary events comment payne et al 2007 1 suggest that there is widespread evidence for a carbonate dissolution surface at the level of the end permian mass extinction and that this crisis was at least partly due to ocean acidification that preferentially affected heavily calcified marine invertebrates these ideas

gradual onset of anoxia across the permian triassic boundary in svalbard norway the permian triassic extinction event is considered to be the most devastating environmental crisis of the phanerozoic with many coinciding factors involved the role of marine anoxia during the extinction is still poorly understood in this study a boreal permian triassic boundary ptb section from svalbard norway has been investigated with the aim of better understanding the timing and nature of local marine anoxia onset and extinction events across the ptb the section comprises the kapp starostin and vikinghogda formations 13corg values indicate the ptb is located within the lower part of the vikinghogda formation lag deposits at the top of the kapp starostin formation indicate a marine hiatus and ensuing transgression during the late permian shortly before the extinction event implying concurrence of major ecological changes and sea level rise pyrite framboid size distributions and total organic carbon toc were used to evaluate bottom water oxygen conditions and show that changes in bottom water redox conditions and extinction are clearly linked oxic to dysoxic bottom water conditions prevailed during deposition of kapp starostin formation sediments and changed to anoxic to euxinic conditions above the formation boundary the onset of anoxia is not abrupt but rather shows a gradual increase within the kapp starostin formation during the late permian the tipping point where bottom waters reach a long term state of anoxia to euxinia coincides with the final extinction event though changes in biotic assemblages at the top of the kapp starostin formation indicate a marine ecosystem crisis prior to this oxygen depletion in the boreal region as seen in our study section and correlating to greenland and arctic canada seems to be consistently more severe than in lower latitude settings

deev jahi model of the permian triassic boundary mass extinction a case for gas hydrates as the main cause of biological crisis on earth the smoking gun revealing the secrets of the end permian mass mortality is a unique 1 2 m thick layer consisting of 5 20 cm long crystals of calcite that occurs precisely at the permian triassic boundary ptb in iran armenia turkey and china this layer is interpreted as synsedimentary abiotic seafloor cement indicative of precipitation from a highly carbonate supersaturated seawater its 13 c composition 13 c 0 pdb is 4 to 5 pdb lower than the typical upper permian values 4 to 5 pdb suggesting the involvement of massive amounts of gas hydrate ch 4 13 c 60 pdb the temporal coincidence of the cement layer with the ptb suggests that the process that promoted seafloor cementation was also responsible for the biological crisis a cementation model is developed based on accumulation dissociation cycle of gas hydrates which also explains the mass extinction at the ptb the upper permian accumulation period of gas hydrates ended abruptly adjacent to the ptb and the dissociation event began releasing 3 2 to 4 7 10 18 g ch 4 into the ocean oxidation of ch 4 in the water column created a seawater that was charged with co 2 an oceanic acid bath and had lower than normal o 2 content but not anoxic this oceanic acid bath first dissolved suspended fine grained carbonate particles and small calcareous organisms followed by extensive dissolution of platform carbonates raising ca 2 and hco 3 concentrations of seawater when the release of ch 4 declined the acid bath ocean became a soda ocean precipitating massive amount of seafloor cements observed globally at the ptb the study suggests that prior to cement precipitation the ptb ocean was charged with co 2 warm had low oxygen high ca 2 and high hco 3 concentrations these conditions collectively created stressful conditions causing the marine mass mortality the leakage of ch 4 to the atmosphere produced a super hot climate resulting in the biological devastation on land the proposed kill mechanism is developed on the basis of the physical clue the cement layer left behind by the killing process the change in ocean chemistry the accumulation dissociation cycles of gas hydrates also explain the 13 c pattern of marine carbonates and the periodicity of mass extinction events during the phanerozoic accumulation periods were long 5 to 20 my providing favorable conditions for ecosystem development pardeess phase the dissociation events were short and catastrophic 10 to 500 ky causing low oxygenation super hot climate and biological devastation doozakh phase it appears that most mass extinctions of the phanerozoic have been related to the internal working of the earth system during the phanerozoic methane has played the role of the deev jahi a female demon in persian mythology whose task is to attack the earth every so often to kill life on land and in sea

survival patterns of macrobenthic marine assemblages during the end permian mass extinction in the western tethys dolomites italy abstract the ecological competition between brachiopods and bivalves is analysed by means of a quantitative palaeoecologic method applied on four assemblages located within a short stratigraphic interval approximately 2 m thick in the lower tesero member of the werfen formation in the southern alps the assemblages originate from the tesero bulla and sass de putia sections the analysed stratigraphic interval uppermost changhsingian in age is located between the early and heaviest phase of the end permian mass extinction which occurred across the bellerophon werfen formational boundary event boundary and the permian triassic boundary chronological boundary when nearly all the permian stenotopic holdovers disappeared these assemblages are characterised by small sized skeletons lilliput effect which represent an adaptive survival strategy in stressed and harsh habitats resulting from the climatic and palaeoceanographic changes connected with the mass extinction the tesero assemblages are dominated by rhynchonelliform brachiopod orbicoelia bed cnt10 or streptorhynchus bed cnt11a which were mostly attached at the top of shallow microbialitic mounds these assemblages are again dominated by permian stenotopic taxa and show a palaeozoic structure the tesero habitat which again permitted the survival of brachiopods represented one of the last refuges in the western tethys on the contrary the bulla bu9 10 and sass de putia wpk13a assemblages are bivalve dominated and thus show an ecologic structure typical of early triassic post extinction marine benthic communities or palaeozoic stressed marine communities the bivalve dominated assemblages proliferated in prevailing muddy siliciclastic substrates with brief episodes of microbial algal growth the most important environmental limiting factors and leading causes of end permian mass extinction are discussed in terms of palaeoautecologic and palaeosynecologic analysis the different taxonomic composition and ecologic structure of the assemblages is related to palaeogeography including water depth and connections with the open sea the brachiopod dominated assemblage exclusive of the tesero section proliferated in microbial carbonate habitats in near shore environments the bivalve dominated assemblages which were more widespread than the brachiopod assemblages in the dolomites and also occurred in other western tethys localities occur in more open and deeper marine environments in the western tethys margins the local distribution of mixed faunas suggests that the extinction of permian stenotopic taxa was caused by the onset of poisonous water on the shelves originating from deep marine environments this extinction pattern appears to be a regional phenomenon and does not seem be applicable on a global scale the extinction events were controlled by a complex network of interactive factors and the survival of faunal elements was probably stochastic

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

high resolution analysis of δ18o in the biogenic phosphate of modern and fossil lingulid brachiopods abstract laser ablation and silver phosphate procedures were used to measure the oxygen isotope composition in organophosphatic shells of lingulid brachiopods at a variety of scales within valves between valves from the same individual between individuals collected at the same location at the same time between localities and between modern and fossil specimens specimens included modern lingulids from several patches in the northern gulf of california mexico and the gulf of nicoya costa rica and fossil specimens from the lower triassic dinwoody formation all specimens display a high degree of intrashell variability frequently exceeding 4 this variability is not symmetrical within the shell does not appear to reflect growth bands and is not consistent with a published lingulid phosphate oxygen isotope thermometer shells analyzed using silver phosphate preparations have variability similar 3 5 to that of shells analyzed using the laser ablation technique ruling out the influence of org

bivalve pavements from shallow water black shales in the early jurassic of northern italy a record of salinity and oxygen depleted environmental dynamics abstract thin shelled bivalve pavements which constitute the eomiodon horizon occur in a distinctive black shale unit in the lowermost part of a lower jurassic carbonate platform sedimentary system of the southern alps italy the eomiodon horizon is characterised by laminated mudstone and fissile dark grey and black organic rich marlstone and claystone yielding abundant bivalve pavements with monotypic to paucispecific assemblages dominated by eomiodon an opportunistic brackish shallow infaunal veneroid bivalve litho and biofacies indicate environmental conditions ranging from nearshore euhaline waters to oxygen depleted brackish lagoon with a high input of terrestrial organic matter culminating in marsh and terrestrial conditions these pavements were analysed using a microstratigraphic approach while considering their taxonomic composition the geometry of the beds their biofabric criteria size sorting abundance fragmentation orientation and disarticulation origin and time averaging these characteristics led to reconstruction of the following palaeoenvironmental dynamics 1 the event concentrations represented by mass mortality of stunted and juvenile individuals caused by anoxia are indicative of deeper and predominantly stagnant parts of the lagoon 2 an increase in shell sizes higher growth rate and a decrease in size sorting and winnowing illustrate higher and more continuous bottom oxygenation and enhanced life in oxygen fluctuated environmental conditions 3 poorly sorted highly fragmented and bioturbated bivalve accumulations indicate the eomiodon habitat here large sized eomiodon specimens record a decrease in water depth and sedimentation rate and almost constantly oxygenated bottom conditions 4 the appearance of byssally attached bivalves lithioperna marks the transition from the muddy soupy substrate of the eomiodon habitat to firm hard bottom conditions this new substrate allowed the settlement of lithioperna a byssate isognomonid which records a shallower and landward marsh setting the eomiodon horizon testifies to a short term warm humid climatic phase and yielded lithioperna the first genus of the lower jurassic lithiotis fauna to appear in southern alps this fauna is composed of large and aberrant bivalves which are spread throughout the lower jurassic tethyan and tropical panthalassian carbonate platforms as a result the eomiodon horizon and its salinity and oxygen depleted environmental setting represent a possible progenitor incubator for the lithiotis fauna

spatial variation in sediment fluxes redox conditions and productivity in the permian triassic panthalassic ocean abstract two permian triassic boundary sections in central japan provide a rare window into environmental conditions within the panthalassic ocean which encompassed more than half the earth s surface at 252 ma integration of petrographic geochemical and time series data provides new insights regarding the fluxes of major and trace components to the sediment as well as environmental conditions in both the deep and intermediate water masses at each study site the ubara section was located in a high productivity peri equatorial location whereas the gujo hachiman section was located in a moderate productivity location at some distance from the paleoequator an upward transition from gray organic poor cherts to black siliceous mudstones at both sites occurred in conjunction with increased primary productivity intensified euxinia within the oxygen minimum zone omz and decimation of the radiolarian zooplankton community euxinia in the omz of the equatorial panthalassic ocean developed episodically for a 200 250 kyr interval during the late permian followed by an abrupt intensification and lateral expansion of the omz around the permian triassic boundary throughout the study interval bottom waters at both sites remained mostly suboxic a finding that counters hypotheses of development of a superanoxic permo triassic deep ocean as a consequence of stagnation of oceanic overturning circulation

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

an analysis of geoid anomalies across the mendocino fracture zone implications for thermal models of the lithosphere geoid height increases in a steplike fashion across oceanic fracture zones owing to the juxtaposition of lithosphere with different ages and density structures at a ridge transform intersection the initial geoid offset depends on the age difference across the fault and is approximately equal to 0 15 m m y of age offset the amplitude and shape of this anomaly will change along the length of a fracture zone depending on how the lithosphere cools if the lithosphere thickens indefinitely boundary layer model then the geoid offset will remain constant although the width of the transition zone from one side of the fracture zone to the other will increase owing to both heat transfer across the fault and an increase in the average depth of compensation if however the lithosphere eventually approaches a constant thickness plate model the total geoid offset will decrease with time an analysis of 18 seasat altimetry profiles across the mendocino fracture zone offset 25 30 m y indicates geoid anomaly amplitudes systematically decrease from more than 4 m across the eastern younger part of the fracture zone to about 1 m across the western older part of the fault although the geoid offsets across the older portion of the mendocino fracture zone may have been underestimated by as much as 20 25 this large decrease in geoid offset strongly suggests that the lithosphere approaches a constant thickness along the older part of the fracture zone a plate thickness of 100 km fits the observed change in geoid offset along the mendocino but with uncertainties in the offset determination the age difference across the older part of the fault and the presence of areas of anomalous depths on both sides of the fracture zone this probably represents a minimum estimate of the total plate thickness

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

early triassic gulliver gastropods spatio temporal distribution and significance for biotic recovery after the end permian mass extinction a reduction in body size lilliput effect has been repeatedly proposed for many marine organisms in the aftermath of the permian triassic pt mass extinction specifically reduced maximum sizes of benthic marine invertebrates have been proposed for the entire early triassic this concept was originally based on observations on early triassic gastropods from the western usa basin and the dolomites n italy and it stimulated subsequent studies on other taxonomic groups however only a few studies have tested the validity of the lilliput effect in gastropods to determine whether the paucity of large sized gastropods is a genuine signal or the result of a poor fossil record and insufficient sampling in combination with a review of the literature we document numerous new abundant large sized gastropods from the griesbachian outcrops of greenland and from the smithian early spathian interval in the southwestern usa we show that large sized gulliver gastropods i were present soon after the pt mass extinction ii occurred in various basins sedimentary facies and environmental contexts from shallow to deeper settings and iii belong to diverse higher rank taxa focusing on the western usa basin we investigate areas from which microgastropod shell beds were previously presented as being typical however we show that gulliver gastropods do occur in the very same areas insufficient sampling effort is probably the main reason for the rarity of reports of large early triassic gastropods which is supported by preliminary rarefaction based simulations finally it appears that the recently documented middle to late smithian climate shifts and the severe end smithian extinction of nekto pelagic faunas did not reduce maximum shell sizes of gastropods

siberian gas venting and the end permian environmental crisis abstract the end of the permian period is marked by global warming and the biggest known mass extinction on earth the crisis is commonly attributed to the formation of the siberian traps large igneous province although the causal mechanisms remain disputed we show that heating of tunguska basin sediments by the ascending magma played a key role in triggering the crisis our conclusions are based on extensive field work in siberia in 2004 and 2006 heating of organic rich shale and petroleum bearing evaporites around sill intrusions led to greenhouse gas and halocarbon generation in sufficient volumes to cause global warming and atmospheric ozone depletion basin scale gas production potential estimates show that metamorphism of organic matter and petroleum could have generated 100 000 gt co2 the gases were released to the end permian atmosphere partly through spectacular pipe structures with kilometre sized craters dating of a sill intrusion by the u pb method shows that the gas release occurred at 252 0 0 4 million years ago overlapping in time with the end permian global warming and mass extinction heating experiments to 275 c on petroleum bearing rock salt from siberia suggests that methyl chloride and methyl bromide were significant components of the erupted gases the results indicate that global warming and ozone depletion were the two main drivers for the end permian environmental crisis we demonstrate that the composition of the heated sedimentary rocks below the flood basalts is the most important factor in controlling whether a large igneous provinces causes an environmental crisis or not we propose that a similar mechanism could have been responsible for the triassic jurassic 200 ma global warming and mass extinction based on the presence of thick sill intrusions in the evaporite deposits of the amazon basin in brazil

strontium isotope evolution of late permian and triassic seawater the 87sr 86sr values based on brachiopods and conodonts define a nearly continuous record for the late permian and triassic intervals minor gaps in measurements exist only for the uppermost brahmanian lower part of the upper olenekian and middle norian and only sparse data are available for the late permian these 219 measurements include 67 brachiopods and 114 conodont samples from the tethyan realm as well as 37 brachiopods and one conodont sample from the mid european middle triassic muschelkalk sea the late permian lower triassic interval is characterized by a steep 1 3 10 3 rise from 0 7070 at the base of the dzhulfian to 0 7082 in the late olenekian a rate of change comparable to that in the cenozoic in the mid triassic anisian and ladinian the isotope values fall to 0 7075 followed again by a rise to 0 7081 in the middle late norian the 87sr 86sr values decline again in the late norian sevatian and rhaetian to 0 7076 the sharp rise in the 87sr 86sr values during the late permian early triassic was coincident with widespread clastic sedimentation because of the paucity of tectonic uplifts the enhanced erosion may have been due to intermittent humid phases during mainly an arid interval coupled with the absence of a dense protective land plant cover following the mass extinction during the latest permian the apex of the 87sr 86sr curve at the olenekian anisian boundary coincides with cessation of the large scale clastic sedimentation and also marks the final recovery of land vegetation as indicated by the renewed onset of coal formation in the middle triassic the rising 87sr 86sr values from the middle carnian to the late norian coincide with the uplift and erosion of the cimmeride indosinian orogens marking the closure of the palaeotethys the subsequent rhaetian decline that continues into jurassic pliensbachian toarcian boundary on the other hand coincides with the opening of the vardar ocean and its eastern continuation in the izmir ankara ophiolitic belt samples from the upper muschelkalk are more radiogenic than the global trend this may reflect separation of the basin from the open ocean due to strong meteoric influx from a large land mass in the north the germanic basin became increasing brackish up section in the north and east but because of the high evaporation rates the salt content was not much reduced in the southern and central basin where a rich but increasingly endemic marine fauna survived