end permian catastrophe by a bolide impact evidence of a gigantic release of sulfur from the mantle our studies in southern china have revealed a remarkable sulfur and strontium isotope excursion at the end of the permian along with a coincident concentration of impact metamorphosed grains and kaolinite and a significant decrease in manganese phosphorous calcium and microfossils foraminifera these data suggest that an asteroid or a comet hit the ocean at the end of permian time and caused a rapid and massive release of sulfur from the mantle to the ocean atmosphere system leading to significant oxygen consumption acid rain and the most severe biotic crisis in the history of life on earth

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

nile damming as plausible cause of extinction and drop in abundance of deep sea shrimp in the western mediterranean over broad spatial scales abstract greatly increased retention of flow in nile river reservoirs was initiated in 1964 after completion of the aswan high dam which induced important oceanographic changes in the mediterranean sea including deep waters below a depth of 150 m based on an analysis of data series starting in the 1940s 1950s the giant red shrimp aristaeomorpha foliacea has become locally extinct off of the catalonian coasts and elsewhere in the northwestern mediterranean at depths of 400 900 m with a simultaneous and significant drop in the catches of red shrimp aristeus antennatus in the second half of the 1960s the extinction and sharp decline of deep shrimp populations off catalonian coast at ca 3200 km westwards from nile delta followed the 1964 drop in nile discharge with a delay of ca 3 5 yrs breakpoint analysis applied to data series the breakpoints detected in the second half of 1960s both in nile runoff and shrimps abundance were independent of climatic events in the study area e g changes in nao and occurred before the increase in fishing effort off catalonian coasts breakpoint in 1973 1974 the levantine intermediate water liw inhabited by a foliacea in the western basin had significant temperature t and salinity s increases in the 1950 1970 period and nile damming has contributed about 45 of the total s increase of western mediterranean deep water masses from the 1960s to the late 1990s skliris and lascaratos 2004 this had to increase for instance liw salinity at its formation site in the eastern mediterranean nile damming was probably a triggering factor for the extinction drop in abundance of deep sea shrimp off catalonian coasts

pyrite framboid evidence for oxygen poor deposition during the permian triassic crisis in kashmir abstract the khunamuh formation of the guryul ravine section in kashmir provides one of the most detailed deep water records of the end permian mass extinction in perigondwanan palaeolatitudes examination of pyrite framboid size distributions and sediment microfabric reveals a distinct change in the uppermost permian strata from nonlaminated pyrite free silty mudstones to finely laminated silty shales rich in framboidal pyrite around 1 m above the base of the formation the size frequency distribution of the framboids is identical to populations from severely oxygen restricted modern depositional environments this change to dysoxic benthic conditions coincides with the rapid demise of diverse permian brachiopod and bryozoan assemblages thus the link between extinction and anoxia is clearly seen at guryul ravine and it provides an interesting contrast to other perigondwanan sections developed in shallower water where both the onset of anoxia and the extinction occurred somewhat later in the earliest triassic

u pb zircon geochronology and tempo of the end permian mass extinction the mass extinction at the end of the permian was the most profound in the history of life fundamental to understanding its cause is determining the tempo and duration of the extinction uranium lead zircon data from late permian and early triassic rocks from south china place the permian triassic boundary at 251 4 0 3 million years ago biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the changhsingian pulse of the end permian extinction corresponding to the disappearance of about 85 percent of marine species lasted less than 1 million years at meishan a negative excursion in 13 c at the boundary had a duration of 165 000 years or less suggesting a catastrophic addition of light carbon

reply to comment on mantle plume the invisible serial killer application to the permian triassic boundary mass extinction by e heydari n arzani and j hassanzadeh palaeogeography palaeoclimatology palaeoecology 264 2008 147 162 abstract in a recent paper heydari e arzani n hassanzadeh j 2008 mantle plume the invisible serial killer application to the permian triassic boundary mass extinction palaeogeography palaeoclimatology palaeoecology 264 147 162 the cause of the end permian mass extinction was once again associated with the eruption of the siberian traps however this work considered the vast outpouring of flood basalts to be an incidental sideshow to the main event the catastrophic release of huge volumes of methane to the atmosphere this was attributed to a selection of sources marine gas hydrates thermogenic methane and methane from permafrost that have been proposed by many authors previously uniquely they suggest that the mantle plume envisaged to have sourced the flood basalts impinged beneath oceanic crust to the north of the siberian flood basalts and that feeder dykes in the continental slope to the south heated sediments and released methane there is no evidence for either of these two new proposed facets to end permian volcanism the paper invokes an oceanic acid bath kill mechanism and dismisses claims for ocean anoxia at this time instead suggesting that end permian oceans were as well ventilated as those pertaining today this latter claim simply ignores a vast body of sedimentological palaeoecological and geochemical evidence for widespread anoxia in ocean and shelf settings at this time the former claim for ocean acidity is equally suspect and based on the notion that a transition from calcite to aragonite precipitating seas occurred at the permian triassic boundary however previous studies have suggested that this interval occurs within a phase of aragonite seas and it is significant that most of the principal contributors to carbonate sediment in the late permian calcareous algae and foraminifera secreted aragonite

enhanced framboidal pyrite formation related to anaerobic oxidation of methane in the sulfate methane transition zone of the northern south china sea abstract many studies have confirmed that size distributions of framboidal pyrite can be an effective indicator of bottom water redox conditions in modern as well as ancient sedimentary environments however one environment in which production of framboidal pyrite has not been sufficiently studied to date is the sulfate methane transition zone smtz in which anaerobic oxidation of methane aom is coupled with microbial sulfate reduction msr to enhance iron sulfide mineral precipitation e g fes2 fes and fe3s4 here we document for the first time size distributions for pyrite framboids from the smtz based on data from two sites in the methane hydrate bearing region of the northern south china sea on the basis of framboid size pyrite concentration and sulfur isotope data we propose new insights into the formation process of authigenic pyrite framboids within the smtz we conclude that 1 enhanced anaerobic oxidation of methane aom not only plays a dominant role in the accumulation of 34s enriched pyrite but also is responsible for formation of highly variable and sometimes exceptionally large pyrite framboids in the smtz 2 most framboids occur in framboid clusters which commonly exhibit rod like shapes secondary overgrowths heavier 34s values and unusual size distributions e g mean size 20 m and standard deviation 3 0 m in the smtz 3 pyrite framboids formed in the smtz which have characteristics different from those formed in the sulfate reduction zone srz do not comment on redox conditions of the overlying water column and 4 framboid occurrences with similar characteristics in ancient marine deposits may be considered indicators of enhanced aom and mark the former position of the smtz in the paleo marine system in addition significant quantities of elemental sulfur were observed in the smtz possibly related to anaerobic oxidation of hydrogen sulfide and fluctuations of the smtz

end permian 252 mya deforestation wildfires and flooding an ancient biotic crisis with lessons for the present abstract current large scale deforestation poses a threat to ecosystems globally and imposes substantial and prolonged changes on the hydrological and carbon cycles the tropical forests of the amazon and indonesia are currently undergoing deforestation with catastrophic ecological consequences but widespread deforestation events have occurred several times in earth s history and these provide lessons for the future the end permian mass extinction event epe 252 ma provides a global deep time analogue for modern deforestation and diversity loss we undertook centimeter resolution palynological sedimentological carbon stable isotope and paleobotanical investigations of strata spanning the end permian event at the frazer beach and snapper point localities in the sydney basin australia we show that the typical permian temperate coal forming forest communities disappeared abruptly followed by the accumulation of a 1 m thick mudstone poor in organic matter that in effect represents a dead zone hosting degraded wood fragments charcoal and fungal spores this signals a catastrophic scenario of vegetation die off and extinction in southern high latitude terrestrial settings lake systems expressed by laterally extensive but generally less than a few metres thick laminated siltstones generally lacking bioturbation hosting assemblages of algal cysts and freshwater acritarchs developed soon after the vegetation die off the first traces of vascular plant recovery occur 1 6 m above the extinction horizon based on analogies with modern deforestation we propose that the global fungal and acritarch events of the permo triassic transition resulted directly from inundation of basinal areas following water table rise as a response to the abrupt disappearance of complex vegetation from the landscape the 13 corg values reveal a significant excursion toward low isotopic values down to 31 a shift of 4 across the end permian event the magnitude of the shift at that time records a combination of changes in the global carbon cycle that were enhanced by the local increase in microbial activity possibly also involving cyanobacterial proliferation we envisage that elevated levels of organic and mineral nutrients delivered from inundated dead forests enhanced weathering and erosion of extra basinal areas together with local contributions of volcanic ash led to eutrophication and increased salinity of basinal lacustrine lagoonal environments we propose that the change in acritarch communities recorded globally in nearshore marine settings across the end permian event is to a great extent a consequence of the influx of freshwater algae and nutrients from the continents although this event coincides with the siberian trap volcanic activity we note that felsic intermediate volcanism was extensively developed along the convergent panthalassan margin of pangea at that time and might also have contributed to environmental perturbations at the close of the permian

age of the emeishan flood magmatism and relations to permian triassic boundary events the permian triassic p t mass extinction the greatest biological mortality event in the earth s history was probably caused by dramatic and global forcing mechanisms such as the siberian flood volcanism here we present the first set of high precision 40 ar 39 ar dating results of volcanic and intrusive rocks from the emeishan traps south china which define a main stage of the flood magmatism at v251 253 ma and a subordinate precursory activity at v255 ma this time span is generally coeval with or slightly older than the age of the p t boundary estimated by the ash beds in the meishan stratotype section and the main eruption of the siberian traps our data reinforces the notion that the eruption of the emeishan traps rather than eruption of the siberian traps accounted for the formation of the p t boundary ash beds in south china the emeishan flood magmatism which occurred in the continental margin comprising thick marine limestone formations moreover may have triggered rapid release of large volumes of methane and carbon dioxide that could have been responsible for the global n 13 c excursion and associated environmental crisis leading to the mass extinction at the p t boundary fl 2002 elsevier science b v all rights reserved

quantitative integration of seismic and gpr reflections to derive unique estimates for water saturation and porosity in subsoil for shallow subsoil the estimates of in situ porosity and water saturation are important but until now it has been difficult to estimate them reliably we relate seismic and gpr reflection coefficients to porosity and water saturation using a shared earth model using this model we propose a method to integrate quantitatively seismic and gpr angle dependent reflection coefficients the new approach has been tested through numerical simulations the results clearly show that from either seismic or gpr data alone it is impossible to obtain unique estimates for porosity and water saturation however a correct integration of those two data types leads to unique and stable estimates at a subsoil layer boundary potential applications of this approach exist in hydrogeology and environmental agricultural and geotechnical engineering

coupled δ44 40ca δ88 86sr and 87sr 86sr geochemistry across the end permian mass extinction event abstract we report high resolution high precision 44 40ca 88 86sr and 87sr 86sr records spanning the permian triassic boundary ptb from the meishan and dajiang carbonate successions in south china the goal of the study was to understand the behavior of ca and sr isotopes during a time period in earth history characterized by severe biological and environmental perturbations including a major mass extinction flood basalt volcanism ocean acidification and sea level fluctuations dajiang displays negative 44 40ca and 88 86sr excursions and invariant 87sr 86sr ratios in the

an extensive anoxic event in the triassic of the south china block a pyrite framboid study from dajiang and its implications for the cause s of oxygen depletion water column oxygen deficiency has been considered as a potent driver of the extinction of marine benthos and is a main feature of marine environments in the aftermath of the end permian mass extinction the record of permian triassic anoxia is more complex than previously thought and is seen to vary between different palaeogeographic settings but a full understanding is hindered by a paucity of evidence during the permian triassic interval the south china block was located equatorially with palaeotethys to the north and western panthalassa to the south this specific configuration provides a unique opportunity to compare the extent and duration of oxygen deficiency in palaeotethys and panthalassa under broadly similar climatic conditions sedimentary facies and pyrite framboid size frequency distributions suggest that the oxygen poor conditions became widespread across the shallow marine carbonate platform of the south china block immediately above the permian triassic boundary and mass extinction level oxygen deficiency was most intense at the southern margin of the block where it met panthalassa proposed drivers of the expansion of oxygen minimum zones into platform settings include enhanced terrigenous input and or ocean stratification or alternatively the upwelling of nutrient rich deep ocean water the former mechanisms are theoretically more likely to have operated in the relatively restricted palaeotethys which was surrounded by ancient lands in contrast panthalassa would likely have experienced stronger oceanic circulation and therefore be more susceptible to the effects of upwelling although variations in the record of the south china block anoxic event might reflect local factors the greater intensity of oxygen deficiency and a concomitant larger negative shift in carbonate carbon isotopes on its panthalassan margin point to a key role for upwelling this mechanism was likely a major driver of the permian triassic global oceanic anoxic event which itself was at least partly responsible for the ongoing inhospitable conditions and delayed recovery following the end permian extinction

geochemical evidence from bio apatite for multiple oceanic anoxic events during permian triassic transition and the link with end permian extinction and recovery abstract a detailed 20 myr redox history of permian to triassic oceans changhsingian to carnian stages has been constructed using ce anomaly ce and th u ratios from conodont albid crown apatite material the results show that the well established phenomenon of intense ocean anoxia coincident with the end permian mass extinction is faithfully recorded in conodont ce and th u data extending this conodont redox record shows that end permian anoxia persisted possibly into the earliest dienerian stage and that two intense oceanic anoxic events also occurred later in the early triassic earliest smithian earliest spathian and middle spathian followed by a weaker manifestation of anoxia in the anisian stage seen in ce data marine benthic radiation following the end permian mass extinction began after the smithian earliest spathian anoxic event suggesting a suppression of evolution prior to this due to these inimical conditions the failure of the middle spathian anoxic event to retard the evolutionary rebound implies shallow shelf seas remained well ventilated at this time even if the oceans did not other attributes of the early triassic record also closely coincide with redox fluctuations phases of anoxia intensification saw the proliferation of microbial carbonates and major negative carbon isotope swings that can be attributed to chemocline shallowing causing alkalinity pulses and enrichment in light remineralised carbon and or indicate a trigger meachnaims related to increased fluxes of light c from siberian volcanic sources

global oolite deposits across the permian triassic boundary a synthesis and implications for palaeoceanography immediately after the end permian biocrisis abstract the permian triassic mass extinction ptme is not only a dramatic loss in biodiversity and major change in ecosystem structures but also coincided with the formation of abundant unusual sedimentary structures of these ooids were widespread in shallow marine carbonate settings during the permian triassic p tr transition and giant ooids occurred more frequently at this critical period than any time during the phanerozoic global review of 43 oolite bearing permian triassic boundary ptb sections with reliable biostratigraphic controls indicates that ooids occurred mostly in coincidence with the latest permian extinction lpe and its immediate aftermath ooids became widespread over extensive regions just after the lpe during the interval corresponding to the conodont hindeodus changxingensis zone they persisted into the earliest triassic until the conodont isarcicella isarcica zone in addition oolites are often found in association with microbialites in low latitude shallow marine settings proliferation of ooids over the p tr transition indicates an extensive range of warm waters with high level of carbonate saturation state that prevailed in the oceans during that time the latest permian ooids were usually small 0 3 to 0 7 mm in diameter aragonitic poorly preserved and recrystallized while moderately to well preserved morphology bimineralic and oversized forms usually occurred in the i isarcica zone of the earliest triassic and afterwards widespread aragonitic ooids in the end of the permian reinforce the scenario that an aragonite sea period may have resulted in the dramatic losses of skeletal organisms that precipitated low mg calcite and hampered their recovery in the aftermath the anomalous primary mineralogy of lower triassic ooids implies that previously assumed stable seawater composition during the early triassic needs to be revaluated

chondritic meteorite fragments associated with the permian triassic boundary in antarctica multiple chondritic meteorite fragments have been found in two sedimentary rock samples from an end permian bed at graphite peak in antarctica the ni fe co ni and p fe ratios in metal grains the fe mg and mn fe ratios in olivine and pyroxene and the chemistry of fe ni p and s bearing oxide in the meteorite fragments are typical of cm type chondritic meteorites in one sample the meteoritic fragments are accompanied by more abundant discrete metal grains which are also found in an end permian bed at meishan southern china we discuss the implications of this finding for a suggested global impact event at the permian triassic boundary

shallow marine dysoxia across the permian triassic boundary evidence from pyrite framboids in the microbialite in south china abstract the end permian mass extinction resulted in the collapse of reef ecosystems and the subsequent formation of microbialites in shallow carbonate platforms in south china large quantities of pyrite framboids are preserved in the microbialites but absent in the underlying skeletal limestone indicating an abrupt shift in water column redox conditions in association with the shallow marine faunal mass extinction detailed study of size distributions of 1374 pyrite framboids found in 9 horizons in laolongdong section in chongqing municipality south china were performed to evaluate this shift in paleo redox condition of the shallow marine environment pyrite framboids in the microbialite average 8 41 m in size comparable with those from modern sediments underlying dysoxic water columns this infers that dysoxic waters in the latest permian might have expanded to reach the shallow marine environments in south china mean diameters of pyrite framboids from mudstones overlying the microbialite are 7 63 m 7 68 m likely indicating continuing intensification of oxygen deficiency in the bottom waters microgastropods ostracods and some foraminifers which survived and flourished in the microbialite almost disappeared during the mudstone deposition possibly reflecting a consequence of oxygen depletion

catastrophic environmental transition at the permian triassic neo tethyan margin of gondwanaland geochemical isotopic and sedimentological evidence in the spiti valley india abstract interpreting global consequences of the permian triassic p tr extinction requires examination across paleogeographic realms of pangaea the spiti valley in india remnant of the peri gondwanan shelf preserved trails of this environmental catastrophe in the neo tethys ocean we document new sedimentological observations and high resolution trace element concentrations and carbon oxygen lead isotope data across the p tr boundary in spiti framboidal pyrites fossils and laminated lithology of the late permian shales indicate deeper anoxic depositional environment while 13 c org excursions of 2 4 and 3 1 in atargu and guling outcrops respectively identify the p tr transition across a clayey partly gypsiferous ferruginous layer sedimentological similarities of this layer to other neo tethyan sections from transcaucasia and iran indicate subaqueous oxidation of shallow marine sediments on a regional scale light rare earth element enriched late permian shales with conspicuous ce eu anomalies reflect their source from the adjacent panjal trap basalts ca 289 ma of kashmir continental crustal nb ta and zr hf anomalies appear at the p tr boundary sediments and prevail through the overlying early triassic carbonates original pb isotope ratios along with an increasing pb abundance closer to the p tr boundary distinguish the volcanic source of the late permian shales from the continental crustal siliciclastic signature of the early triassic carbonates our 13 c org trace element and pb isotope record from spiti indicate catastrophic changes in sediment sources and facies with effects on carbon cycle and are consistent with an abrupt episode of marine regression and erosional forcing also observed elsewhere along northern gondwanaland simultaneous eruption of siberian volcanics and bolide impacts in parana basin of brazil and elsewhere implicating impact triggered volcanism left catastrophic regional global imprints on sea level climate marine anoxia and tectonic stability that connected the p tr crisis across terrestrial and marine realms worlwide

a tale of two extinctions converging end permian and end triassic scenarios the end permian c 252 ma and end triassic c 201 ma mass extinction events are commonly linked to the emplacement of the large igneous provinces of the siberia traps and central atlantic magmatic province respectively accordingly scenarios for both extinctions are increasingly convergent and cross fertilization of ideas has become important here we present a synthesis of extinction scenarios based on a critical assessment of the available palaeontological sedimentological geochemical and geophysical evidence how similar were the extinction events what gaps exist in our understanding and how can a comparison of the events enhance our understanding of each event individually our focus is on the most important proximate kill mechanisms including climate change and atmospheric pollution increased soil erosion weathering and runoff forest dieback and the spread of pathogens and ocean temperature changes anoxia and acidification there is substantial evidence to suggest that very similar kill mechanisms acted upon late permian as well as late triassic ecosystems strengthening the hypothesis that the ultimate causes of the mass extinction events were similar

evidence for wildfire in the meishan section and implications for permian triassic events polynuclear aromatic hydrocarbons pahs and black carbon bc in sediments are powerful tools in the identification of the combustion process throughout geologic history in this study combustion derived pahs and bc were carefully investigated in sediments from the global stratotype section and point of the permian triassic p tr boundary in meishan china quantitative analyses of combustion derived pahs and bc demonstrate anomalously high concentrations in the boundary event beds that coincide with the mass extinction horizon the prevalence of parent polynuclear aromatics e g phenanthrene in pahs together with non metric multidimensional scaling analysis confirms that the pahs are mainly derived from vegetation burning instead of having a coal and or oil origin bc detected in sediment occurs in various forms from large irregular charcoal particles to fine aciniform soot with an equivalent reflectance of up to 3 5 the results strongly suggest that a wildfire occurred during the p tr boundary which served as one of the possible triggers of mass extinction on land the wildfire occurrence indicates that the o2 concentration of the atmosphere during or before the p tr mass extinction was probably 17 the temporal coincidence of the mass extinction with intensive volcanic eruption marine anoxia and wildfire events in the region of the meishan section provides new insight into the mechanisms of the p tr biotic crisis our results show that wildfires could have played an important role in the collapse of the ecosystem in the meishan p tr events

isotopic signatures of mercury contamination in latest permian oceans sedimentary records from the northwest margin of pangea and the tethys show anomalously high hg levels at the latest permian extinction boundary background 202 hg values are consistent with normal marine conditions but exhibit negative shifts coincident with increased hg concentrations hg isotope mass independent fractionation 199 hg trends are consistent with volcanic input in deep water marine environments in contrast nearshore environments have 199 hg signatures consistent with enhanced soil and or biomass input we hypothesize that the deep water signature represents an overall global increase in volcanic hg input and that this isotope signature is overwhelmed in nearshore locations due to hg from terrestrial sources high productivity nearshore regions may have experienced stressed marine ecosystems due to enhanced hg loading

a permian triassic boundary microbialite deposit from the eastern yangtze platform jiangxi province south china geobiologic features ecosystem composition and redox conditions abstract a permian triassic p tr boundary microbialite ptb microbialite deposit occurs near xiushui on the southern margin of the eastern yangtze platform south china this 2 m thick microbialite overlies uppermost permian bioclastic limestone with a 5 cm thick oolite like grainstone layer at the contact this ptb microbialite consists of lower thrombolite 1 5 m thick and an upper dendrolite 0 5 m thick the thrombolite interval is characterized by a clotted texture of reddish sparitic patches embedded in a gray micritic matrix whereas the dendrolite texture consists of brownish sparitic patches embedded within a yellow micritic matrix abundant calcified microbes occur in both the thrombolite and the dendrolite including 1 columnar and clustered fabrics which are especially rich in the thrombolite assigned as products of gakhumella or related microorganisms and 2 microspheroids 40 60 m in diameter with different interior structures these calcimicrobes are considered to have played an important role in constructing the xiushui ptb microbialite the demise of the microbialite was likely due to a sea level fall during the early griesbachian lowermost triassic which resulted in a lowering of the wave base thereby destroying the microbialite frameworks and facilitating the deposition of winnowed skeletal grainstone metazoan community structures within the microbialite changed sharply across the end permian extinction horizon which is placed at a sharp negative shift in 13 c carb quantitative analyses show that the xiushui microbialite community is similar to that of chongyang and cili microbialites this is probably because all of these microbialites grew along the margins of the lower yangtze region during the p tr transition however unlike other ptb microbialites the xiushui ecosystem contains fairly abundant metazoans which are dominated by ostracods with minor occurrences of foraminifers microgastropods and microconchids both the ostracod assemblage and the pyrite framboid analyses indicate an upper dysoxic zone to a well oxygenated condition for the xiushui microbialite this implies that some ptb microbialite ecosystems developed in conditions that were not always harsh instead some were hospitable for some metazoans to survive immediately after the end permian crisis considering that the redox conditions indicated by ptb microbialites are quite variable we infer that oxygen levels probably were not the crucial factor affecting the growth of the ptb microbialites

pyrite framboids in the permian triassic boundary section at meishan china evidence for dysoxic deposition pyrite framboid evidence from the permian triassic global stratotype at meishan china indicates the late permian mass extinction is closely associated with a dramatic decline of benthic oxygen levels sizes and abundances of the framboids were determined from acid residues and in situ on polished sections of the samples the framboids are abundant in the thin pyrite lamina on the top of bed 24e the upper layer of bed 24 and beds 25 26 and 29 rare in bed 24e and bed 28 but absent in bed 27 they have narrow size distributions with average diameters from 4 6 mu m to 8 7 mu m which are similar to those formed under anoxic dysoxic conditions the abundances and mean diameters of the pyrite framboids indicate redox conditions of deposition changing from upper dysoxia bed 24e and lower dysoxia pyrite lamina beds 25 and 26 to oxygenation bed 27 and again to upper dysoxia bed 28 and lower dysoxia bed 29 our discovery confirms a worldwide dysoxic marine event during the permian triassic transition suggestive of a direct relationship with the permian triassic marine mass extinction c 2007 elsevier b v all rights reserved

basaltic volcanism and mass extinction at the permo triassic boundary environmental impact and modeling of the global carbon cycle the siberian traps represent one of the most voluminous continental flood basalt provinces on earth the mass extinction at the end of the permian was the most severe in the history of life in the present paper these two major concurrent events that occurred are analysed and a geochemical model coupled with an energy balance model is used to calculate their environmental impact on atmospheric co2 oceanic 13c and marine anoxia the latitudinal temperature gradient is reduced relative to today resulting in warmer temperatures at high latitudes the warmer climate and the presence of fresh basaltic provinces increase the weatherability of the continental surfaces resulting in an enhanced consumption of atmospheric co2 through weathering first the eruption of the siberian traps is accompanied by a massive volume of 13c depleted co2 degassed from the mantle and added to the ocean through silicate weathering thus lowering marine 13c second the rapid collapse in productivity induces a strong decrease in the global organic carbon burial this too tends to increase the proportion of light carbon in the ocean these two effects can explain the low 13c values across the pt boundary and methane release need not be invoked to explain the 13c fluctuations it is proposed that the phosphorus cycle which drives primary production in the model plays an important role on the recovery of productivity and the 13c variations

pattern of marine mass extinction near the permian triassic boundary in south china the meishan section across the permian triassic boundary in south china is the most thoroughly investigated in the world a statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251 4 million years ago coincident with a dramatic depletion of 13ccarbonate and an increase in microspherules

evolutionary dynamics of the permian triassic foraminifer size evidence for lilliput effect in the end permian mass extinction and its aftermath abstract there is growing evidence of the lilliput effect in the end permian mass extinction and its aftermath however very little has been published on assessing the lilliput effect on protozoans in the early triassic based on quantitative analysis of a great quantity of samples from outcrop sections this study investigates foraminiferal test size variations through the changhsingian to the olenekian based on fossil records from three outcrop sections in south china the sharp reduction in foraminifer sizes coincides with the first or main episode of the end permian mass extinction foraminifers remained small in sizes in the early induan their body sizes increased slowly in the late induan to olenekian but never recovered to the pre extinction test size levels the lilliput effect on foraminifera in the aftermath of the end permian crisis is indicated by the extinction of large taxa decrease in size for surviving taxa and rise of small sized new forms physiological reactions of various foraminifer groups reveal that several defaunation events such as anoxia ocean acidification and global warming that prevailed through the permian triassic interval may be responsible for both the end permian crisis and the lilliput effect

platinum group elements of the meishan permian triassic boundary section evidence for flood basaltic volcanism abstract permian triassic boundary sections record the most severe mass extinction event in geological history however there is a long standing controversy of whether bolide impact and or basaltic flood volcanism triggered the mass extinction platinum group elements pges are enriched in most extraterrestrial materials but highly depleted in the terrestrial crust materials we analyzed ir ru rh pt and pd in a set of samples from the global stratotype section and point gssp of the permian triassic boundary at meishan china using isotope dilution inductively coupled plasma mass spectrometry id icp ms and nickel sulfide fire assay nis fa combined with te coprecipitation the samples have no ir anomaly 5 53 pg g and their pge patterns normalized to chondrites are highly fractionated with ir pd ratios of 0 02 0 03 ci distinct from most extraterrestrial materials in contrast these patterns are closely parallel to those of the siberian and probably emeishan flood basalts suggestive of possible sources of pges from the basalts the abundances of pges increase in order of the pyrite lamina on the top of bed 24 bed 25 and bed 26 and then decrease to bed 28 probably indicative of a maximum eruption of the flood basalts during deposition of bed 26 the new data favor massive volcanism rather than extraterrestrial impact as a major cause of the permian triassic boundary mass extinction

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

carbon isotope and iridium event markers near the permian triassic boundary in the meishan section zhejiang province china abstract systematic investigations for carbon isotopes and iridium of the meishan section were carried out using very narrow sampling intervals the high resolution results demonstrate the following characteristics 1 a large drop in 13c 7 cm above the base of the triassic with a magnitude of about 6 2 a sharp ir peak of 2 02 ppb 10 cm above the base of the triassic whereas the ir mean of six samples equals 0 4 ppb the large negative carbon isotope shift the ir anomaly within a thin sublayer and microspherules all occur within a 20 cm thick section above the base of the triassic which has been defined to coincide with an abrupt facies change from carbonate to clay the geochemical results and the microspherules suggest that the permian triassic boundary event was catastrophic and probably caused by an extraterrestrial impact

photic zone euxinia during the permian triassic superanoxic event carbon and sulfur isotopic data together with biomarker and iron speciation analyses of the hovea 3 core that was drilled in the perth basin western australia indicate that euxinic conditions prevailed in the paleowater column during the permian triassic superanoxic event biomarkers diagnostic for anoxygenic photosynthesis by chlorobiaceae are particularly abundant at the boundary and into the early triassic similar conditions prevailed in the contemporaneous seas off south china our evidence for widespread photiczone euxinic conditions suggests that sulfide toxicity was a driver of the extinction and a factor in the protracted recovery

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

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

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

extent and duration of marine anoxia during the frasnian famennian late devonian mass extinction in poland germany austria and france the intensity and extent of anoxia during the two kellwasser anoxic events has been investigatedinarangeofeuropeanlocalitiesusingamultidisciplinaryapproach pyriteframboidassay gamma ray spectrometry and sediment fabric analysis the results reveal that the development of the lower kellwasser horizon in the early late rhenana zone frasnian stage in german type sections does not always coincide with anoxic events elsewhere in europe and in some locations seafloor oxygenation improves during this interval thus this anoxic event is not universally developed in contrast the upper kellwasser horizon developed in the late linguiformis zone frasnian stage in germany correlates with a european wide anoxic event that is manifest as an intensification of anoxia inbasinallocationstothepointthatstableeuxinicconditionsweredeveloped forexample inthebasins of the holy cross mountains poland the interval also saw the spread of dysoxic waters into very shallow water for instance reefal locations and it seems reasonable to link the contemporaneous demise of many marine taxa to this phase of intense and widespread anoxia in basinal locations euxinic conditions persisted into the earliest famennian with little change of depositional conditions only in the continental margin location of austria was anoxia not developed at any time in the late devonian consequently it appears that the upper kellwasser anoxic event was an epicontinental seaway phenomenon caused by the upward expansion of anoxia from deep basinal locales rather than an oceanic anoxic event that has spilled laterally into epicontinental settings

search for evidence of impact at the permian triassic boundary in antarctica and australia life on earth was almost destroyed some 250 m y ago in the most profound of all known mass extinction events we investigated the possible role of impact by an extraterrestrial bolide through chemical and mineralogical characterization of boundary breccias search for shocked quartz and analysis for iridium in permian triassic boundary sections at graphite peak and mount crean antarctica and wybung head australia thin claystone breccias at the isotopically and paleobotanically defined boundary at all three locations are interpreted as redeposited soil rather than impact ejecta the breccias at all three locations also yielded shocked quartz but it is an order of magnitude less abundant 0 2 vol and smaller only as much as 176 micrometers m diameter than shocked quartz at some cretaceous tertiary boundary sites faint iridium anomalies were detected up to 134 pg g 1 these values are an order of magnitude less than iridium anomalies at some cretaceous tertiary boundary sites furthermore peak iridium values are as much as 1 m below the isotopically and paleobotanically defined boundary the idea that impact caused the extinctions thus remains to be demonstrated convincingly