millennial scale ocean redox and δ 13 c changes across the permian triassic transition at meishan and implications for the biocrisis the permian triassic extinction was the largest phanerozoic mass extinction event yet its ultimate causes remain unresolved ocean redox conditions global warming and carbon cycle perturbations owing to massive volcanism and their inter relationships are keys to resolve the origins of this event we here assess such relationships using a method to obtain an instantaneous stratigraphic response from high resolution millennial scale records of carbonate 13c and pyrite framboid size distributions across the permian triassic boundary ptb at meishan china we report two gradual long term negative 13c shifts before and after the ptb late permian ocean redox conditions varied through three successive oxic dysoxic dysoxic euxinic and high frequency euxinic stages oxic and high frequency euxinic events occurred in the early griesbachian and middle griesbachian respectively the short term euxinia events were not associated with the negative 13c excursions siberian volcanism could have produced large light carbon inputs global warming and low oxygen conditions at intermediate ocean depths but it may not directly drive high frequency euxinia across the ptb long term dysoxia and occasional euxinia well before the ptb stressed mobile macroorganisms and caused gradual extinction before the major extinction event high frequency latest permian euxinia reduced overall biotic adaptability and caused the initial rapid mass extinction increasing temperatures and other deleterious environment factors then reinforced the extinction process oxic conditions contributed to biotic recovery immediately after the mass extinction in the early griesbachian further millennial scale dysoxic euxinic alternations in the middle griesbachian would have prolonged early triassic biotic recovery

variations in pyrite texture sulfur isotope composition and iron systematics in the black sea evidence for late pleistocene to holocene excursions of the o2 h2s redox transition time dependent variations in the physicochemical properties of pyrite were investigated in four sediment cores from the black sea in the laminated deep basin sediments of unit i and unit ii 86 of pyrite particles are present as fine grained framboidal aggregates in these sediments the dominance of pyrite framboids with a narrow size distribution and maximum size 18 m is evidence of syngenetic water column pyrite formation subjacent to the o2 h2s boundary sediments from the basin margin collected below the impingement of the o2 h2s boundary contain an increased proportion of fine grained euhedral grains of pyrite relative to framboidal aggregates suggesting increased additions of diagenetic pyrite below the sediment water interface the more efficient reduction and sulfidation of iron in the water column of the central region of the basin implies a more reactive source of iron there compared to the basin margins and is tied to increasing pyrite as framboids and greater degrees of pyritization dop in the basin center relative to the basin margins an evaluation of fe s c relations indicates that pyrite formation was limited by sulfate availability during deposition of the oldest lacustrine sediments of unit iii c limited for upper unit iii due to the input of sulfate rich mediterranean seawater and fe limited in the laminated organic carbon rich sediments of units i and ii these changes in pyrite limiting factors occurred within 4 m of compacted burial representing 15 ka sediment fabric and framboid size distributions at a shallow basin margin site suggest that during two extended periods of unit ii deposition the o2 h2s transition retreated to depths below 200 m however during these same intervals the 34s of pyrite remains uniform compared to overlying and underlying laminated sediments implying that this chemical signature may not be uniquely tied to the position of the o2 h2s boundary relative to the sediment water interface but rather is likely related to biogeochemical processes

biogeochemical controls on photic zone euxinia during the end permian mass extinction geochemical biomarker and isotopic evidence suggests that the end permian was characterized by extreme oceanic anoxia that may have led to hydrogen sulfide buildup and mass extinction we use an earth system model to quantify the biogeochemical and physical conditions necessary for widespread oceanic euxinia and hydrogen sulfide release to the atmosphere greater than threefold increases in ocean nutrient content combined with nutrient trapping ocean circulation cause surface water h 2 s accumulation in the paleo tethys ocean and in areas of strong upwelling accounting for the presence of sulfide oxidizing phototrophs in the model suppresses but does not prevent widespread release of h 2 s to the atmosphere evidence from the geologic record is consistent with modeled geochemical distributions of widespread nutrient induced euxinia during the end permian suggesting h 2 s toxicity and hypercapnia may have provided the kill mechanism for extinction

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

two pulses of oceanic environmental disturbance during the permian triassic boundary crisis abstract pyrite morphology iron speciation and pyrite sulfur isotope data from the xiakou section hubei province south china were integrated to explore oceanic environmental variations through the permian triassic transition and their possible relations to the largest mass extinction in earth history high ratios of highly reactive iron to total iron fehr fet 0 6 and pyrite iron to highly reactive iron fepy fehr 0 7 together with a high abundance of small mean diameter 0 6 along with lower values of fepy fehr

development of a largely anoxic stratified ocean and its temporary massive mixing at the permian triassic boundary supported by the sulfur isotopic record systematic sulfur isotope data for whole rock sulfides have been obtained from the chert dominated continuous pelagic sedimentary sequences spanning the permian triassic p tr boundary at tenjinmaru in the chichibu terrane and at sasayama in the tanba terrane in japan the p tr boundary is characterized by the occurrence of siliceous shales in association with a carbonaceous black mudstone which is similar in appearance to the worldwide distributed cretaceous tertiary k t boundary claystone the observed data clearly demonstrate a significant bimodalism the 34s 32s ratios with respect to cdt are generally low throughout the middle permian ca 39 to 25 0 and show a remarkable increase beginning in the lower upper permian and persisting into the lower triassic ca 20 to 2 0 with a temporary and drastic negative shift down to roughly the same isotopic level as in the middle permian just at the suspected p tr boundary ca 41 to 23 0 interestingly the mode of isotopic excursion across the p tr boundary is in striking contrast to that across the k t boundary which was recently described at kawaruppu in hokkado japan the apparent extent of fractionation with respect to contemporaneous seawater sulfate in the high 34s 32s group lies within the range of 25 10 0 which is quantitatively equivalent to the currently confirmed range of kinetic isotope effect during bacterial dissimilatory sulfate reduction and that in the low 34s 32s group mostly exceeds this range giving the values typically in the range of 45 10 0 which is similar to what is generally observed in the present day oceanic sediments the present data would provide strong evidence for the development of a largely stagnant anoxic stratified ocean which presumably began to form in the lower upper permian and persisted into the lower triassic and for a brief episode of its temporary massive mixing just at the suspected p tr boundary such an oceanic oxic anoxic history may account to some extent for the relatively high enrichments of chalcophile elements in basal triassic sediments in the world and add a significant constraint to the current arguments on the cause and consequence of the terminal permian mass extinction

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

evidence for recurrent early triassic massive volcanism from quantitative interpretation of carbon isotope fluctuations abstract carbon cycle disturbance associated with mass extinction at the end of the permian period continued through the early triassic an interval of approximately 5 million years coincidence of carbon cycle stabilization with accelerated middle triassic biotic recovery suggests a link between carbon cycling and biodiversity but the cause of early triassic carbon isotope excursions remains poorly understood previous modeling studies have focused exclusively on the initial negative excursion in 13c across the permian triassic boundary and have not addressed the cycles of positive and negative excursions observed through the early triassic this study uses a simple carbon cycle box model to investigate potential causes underlying the series of early triassic carbon isotope excursions and to assess possible relationships between isotope excursions and coeval patterns of carbonate deposition according to the model introduction of carbon with the isotope composition of volcanic co2 produces small negative carbon isotope excursions followed by larger and more protracted positive excursions positive excursions result because increased pco2 causes warming enhancing marine anoxia and associated regeneration of phosphate and thus allowing greater productivity in addition carbonate weathering is more sensitive than organic carbon weathering to changes in atmospheric pco2 and climate causing an increase in the overall 13c composition of weathered carbon therefore the full early triassic record of negative and positive carbon isotope excursions can only be accounted for within the model by several pulses of carbon release characterized by varying mixtures of organic and mantle isotope compositions thermal metamorphism of coal and carbonate rocks in the crust of the siberian craton during eruption of the siberian traps flood basalts provides the most plausible mechanism for such a carbon release scenario if multiple episodes of co2 release account for early triassic carbon cycle instability regardless of their precise trigger then cessation of co2 release is likely to explain acceleration of biotic recovery early in the middle triassic

palaeokarst influenced depositional and diagenetic patterns in upper permian carbonates and evaporites karstryggen area central east greenland the karstryggen area of eastern greenland represents the western edge of sedimentation in the jameson land basin an arm of the northern zechstein seaway upper permian strata of this area were deposited as two major sequences the first marine incursion transgressed largely peneplaned lower permian strata and deposited thin paralic conglomerates sandstones and shales the huledal formation followed by a thick package of carbonates and evaporites the karstryggen formation although the karstryggen formation represents the transgressive maximum of this sequence it contains only marginal or restricted marine strata including micritic stromatolitic and peloidal carbonates and thick but localized bedded gypsum deposits these lithofacies indicate that relatively arid climates prevailed in this basin as in most of the zechstein region a major regression associated with a change to a more humid climate terminated karstryggen sedimentation pre existing evaporites and carbonates underwent diagenetic alteration including widespread calcitization and dissolution of gypsum more importantly topographic relief in excess of 120 m was generated by fluvial drainage systems and karstic sinkholes a second marine incursion accompanied by a return to a semi arid climate drowned this high relief topography producing a complex sequence of strata the wegener halvo formation in which sedimentation was greatly influenced by the rugged underlying terrain marine cemented algal molluscan grainstones draped pre existing palaeotopography during the initial stages of flooding continued drowning led to differential sedimentation on highs and in lows oolitic and bryozoan brachiopod grainstones formed as shoals on the crests of most prominences whereas shales conglomeratic debris flows evaporites or oolitic turbidites were deposited in the lows more restricted sedimentation took place in the westernmost areas which lay closest to the mainland shoreline and were situated to the west of a palaeotopographic ridge there oolitic stromatolitic and evaporitic strata were deposited under hypersaline conditions indicative of a return to more arid climatic conditions three subcycles mark smaller scale relative changes of sea level that occurred during deposition of the wegener halvo formation they are delimited by regional surfaces with moderate relief 5 20 m developed during subaerial exposure widespread diagenetic changes including leaching of aragonitic grains dissolution collapse brecciation of evaporites and meteoric calcite cementation occurred in association with these smaller scale sequence boundaries again reflecting climatic oscillations relative sea level fluctuations coupled with regional climate changes played a dominant role in determining both depositional and diagenetic relations in these strata these features undoubtedly extend into subsurface parts of this basin as well as into yet unexplored areas of the northern zechstein basin and barents shelf and may have economic significance for the localization of hydrocarbons

geochemistry of post extinction microbialites as a powerful tool to assess the oxygenation of shallow marine water in the immediate aftermath of the end permian mass extinction rapid and profound changes in earth surface environments and biota across the permian triassic boundary are well known and relate to the end permian mass extinction event this major crisis is demonstrated by abrupt facies change and the development of microbialite carbonates on the shallow marine shelves around palaeo tethys and western panthalassa microbialites have been described from a range of sites in end permian and basal triassic marine sedimentary rocks immediately following the end permian mass extinction here we present geochemical data primarily focused on microbialites our geochemical analysis shows that u v mo and ree ce anomaly may be used as robust redox proxies so that the microbialites record the chemistry of the ancient ambient sea water among the three trace metals reputed to be reliable redox proxies one v is correlated here with terrigenous supply the other two elements u and mo do not show any significant authigenic enrichment thereby indicating that oxic conditions prevailed during the growth of microbialites ree profiles show a prominent negative ce anomaly also showing that the shallow marine waters were oxic our geochemical data are consistent with the presence of some benthic organisms ostracods scattered microgastropods microbrachiopods and foraminifers in shallow marine waters that survived the mass extinction event

association of 34s depleted pyrite layers with negative carbonate δ13c excursions at the permian triassic boundary evidence for upwelling of sulfidic deep ocean water masses 1 a marine permian triassic boundary ptb section at nhi tao vietnam contains a series of at least 9 pyritic horizons characterized by concurrent decreases in pyrite s 34spy and carbonate c isotopic compositions 13ccarb the first and largest of the events that precipitated these pyritic horizons was coincident with the late permian mass extinction while subsequent events were generally smaller and occurred at quasiperiodic intervals of 20 to 30 ka a near complete lack of organic carbon to drive bacterial sulfate reduction in sediment pore waters among other considerations argues against a diagenetic control for these relationships rather the covariant patterns documented herein are most easily explained as the product of recurrent upwelling of anoxic deep ocean waters containing 34s depleted hydrogen sulfide and 13c depleted dissolved inorganic carbon the sulfide 34s record of the study section represents a mixture of a small amount of isotopically heavy authigenic pyrite formed via in situ bacterial sulfate reduction with a generally larger quantity of isotopically light syngenetic pyrite precipitated within the water column during upwelling episodes although upwelling of toxic deepwaters has been invoked in earlier studies as a mechanism for the late permian marine mass extinction this is the first study to 1 document patterns of pyrite 13ccarb covariation that strongly support upwelling as a major process at the ptb and 2 provide evidence of multiple quasiperiodic upwelling events that may reflect reinvigoration of global ocean overturn following a prolonged interval of late permian deep ocean stagnation

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

phanerozoic large igneous provinces lips heatt haline euxinic acidic thermal transgression episodes and mass extinctions abstract the phanerozoic consists of three mutually exclusive climate states icehouse greenhouse and hothouse the greenhouse is the default state representing 70 of the phanerozoic it is characterized by a weak thermal mode pole driven deep water formation with little or no continental sea ice and weakly oxic cool water sinking near the poles nitrogen limitation characterizes greenhouse oceans in which ammonium may be the dominant bioavailable form of nitrogen the steady state greenhouse default must be forced to produce either of the other two states continent continent collision produces the intense chemical weathering that draws down atmospheric co2 and results in the icehouse state that comprises 20 25 of the phanerozoic icehouses have ice caps in contact with the ocean that produce icebergs and foster sea ice formation sea ice formation fills the ocean with highly oxic phosphorus limited icewater except for a thin layer of warm surface water in the tropics of the 23 most conspicuous mass extinctions of the phanerozoic including the late ediacaran 4 are associated with ice volume related regressions and 3 are problematic we suggest that the other 16 mass extinctions occurred when greenhouse climate was forced to hothouse climate large igneous provinces lips can trigger the heatt haline euxinic acidic thermal transgression mechanism which can force greenhouse climate to a hothouse climate state the rapid voluminous co2 emissions of lips cause a series of events that result in very slow but pronounced haline mode circulation mid latitude driven deep water formation that produces warm saline bottom water at very dry hot subtropical and middle latitudes this water upwells at the poles causing warm and moist equable climate hothouse development promotes deep sea anoxia that is generated in concert with co2 buildup and warming the spread of anoxia favors reduced nitrogen over nitrate and limited iron dust curtails nitrogen fixation this leads to dominance of primary productivity by primitive green algae and or cyanobacteria progression to euxinia that reaches the photic zone severely curtails primary productivity via poisoning even as availability of usable nitrogen plummets the result is eukaryotic mass extinction we suggest that the 16 phanerozoic mass extinctions referred to above resulted at least in part from the heatt process evidence for this relationship at 11 of the most severe extinctions is convincing data sets for the other 5 are strongly suggestive of heatt related mass extinction but do not yet have enough documentation to reliably characterize them as heatt episodes

geochemistry of late permian to early triassic pelagic cherts from southwest japan implications for an oceanic redox change major trace and rare earth element abundances were determined for the southwestern japanese pelagic chert sequence from the early late permian to early early triassic to investigate a redox change in deep sea pelagic environments before and at the permo triassic boundary ptb 251 ma the sequence was primarily deposited in the deep sea of the superocean panthalassa and then was accreted to japan in the middle jurassic a remarkable lithostratigraphic change from red chert to siliceous carbonaceous claystone through gray chert is observed in this sequence constituent elements for these sedimentary rocks are essentially derived from two sources 1 an ancient seawater via biogenic mainly radiolarian hydrothermal and authigenic materials and 2 an average shale like terrigenous material the present measurement demonstrates significant stratigraphic changes of the ce cenon ter value estimated ce anomaly value of non terrigenous component recalculated by subtraction of terrigenous rees from bulk rees and the mn te sample mn te paas value excess mn component other than terrigenous one te terrigenous elements including ti al nb hf th paas post archean average australian shale in the permian chert the ce cenon ter values increase from 0 2 to 1 and the mn te sample mn te paas values decrease up section suggesting that the redox condition of deep sea open ocean changed from oxic to suboxic in an interval of approximately 10 myr the fe te sample fe te paas and mn te sample mn te paas values of carbonaceous claystone near or at the ptb are less than unity suggesting that reductive dissolution of iron and manganese occurred under an anoxic condition this supports the idea of the ptb oceanic anoxia in the superocean panthalassa the present data suggest that the anoxic condition prevailed in the deep sea pelagic regions for an extremely long period much more than 10 myr from the middle late permian to early early triassic this long term development of widespread oceanic anoxia may have been linked to the greatest mass extinction of the phanerozoic

processes affecting groundwater chemistry in a zone of saline intrusion into an urban sandstone aquifer abstract samples have been collected from inflows into railway tunnels in the triassic sandstone aquifer beneath liverpool and the mersey estuary england u k these provide a profile through a saline freshwater mixing zone analyses were made of major anions and cations 34s and 18o in so4 13c in dissolved inorganic c and 87sr 86sr the data demonstrate that the presence of a low permeability fault exerts a strong control on the local groundwater chemistry on the estuary side of the fault groundwater chemistry is dominated by mixing of intruding estuary water which is modified by so4 reduction and calcite dissolution with fresh groundwater the environment of so4 reduction in the tidal estuary is one of repeated reduction and re oxidation of s in an open system and has resulted in virtually no change in s isotopic composition but an enrichment in residual so4 18o of 1 5 groundwater chemistry on the landward side of the fault is primarily the result of recharge in an urban environment there is also evidence that saline water has been present in this region of the aquifer in the past and that this has now been flushed by fresh groundwaters this saline water was either transported along the landward side of the fault from nearer the estuary or more probably transmitted across the fault both mechanisms would have been driven by large landward head gradients caused by heavy industrial abstraction earlier this century this has produced a zone of groundwaters depleted in ca and radiogenic sr and enriched in na as a result of ion exchange between the fresh groundwaters and the aquifer previously occupied by more saline water sulphur isotopic composition however shows no variation since so4 does not undergo significant ion exchange a tracer test from a borehole to the tunnels showed multiple breakthroughs to some locations indicating a number of different flow paths through the aquifer the maximum flow velocity recorded in this test was 140 m d suggesting flow along fractures

changes in biomarker abundances and sulfur isotopes of pyrite across the permian triassic p tr schuchert dal section east greenland abstract in this study we report on biomarker abundances through parts of the permian triassic boundary ptb of schuchert dal east greenland that contains rich marine faunal records and excellent terrestrial palynological records biomarker abundances and sulfur isotopes are used to correlate the series of events including changes in element cycling and associated redox conditions of the ocean surrounding the collapse of the marine and terrestrial ecosystems through this record of a major crisis of life on earth during a mass extinction episode the upper schuchert dal formation contains a low diversity palynological assemblage ascribed to arborescent cordiaite conifer pteridosperm vegetation samples from this pre collapse interval are characterised by high abundances of dibenzofuran dbf dibenzothiophene dbt and biphenyl since these compounds have similar base structures and show comparable abundance curves it is plausible that they probably derive from a common source we propose that phenolic compounds of lignin of the woody plants present during this period could be the source for dbf dbt and biphenyl the redox conditions during this period of time also support the formation of dbf and dbt just above the extinction interval there is a dramatic decrease in the abundances of dbf and dbt which occurs at the same time as a sudden change in the stable sulfur isotopic composition 34s of pyrite indicating a change in redox conditions from oxic to anoxic euxinic conditions 34s values leading up to the extinction are highly depleted in the heavy sulfur isotope about 40 vs vcdt whilst shortly after the extinction interval much more positive isotope values are observed about 25 an inferred change in the biogeochemical sulfur cycle is supported by facies evidence from similar neighbouring sections it is suggested that two processes are operating closely here 1 changes in redox conditions and 2 extinction and or transgression accounting for the absence of woody material

rapid and synchronous collapse of marine and terrestrial ecosystems during the end permian biotic crisis a newly studied permian triassic p tr boundary section in jameson land east greenland contains an abundant and well preserved marine fauna as well as terrestrial palynomorphs for the first time it is possible to compare the biotic crises of the marine and terrestrial realms using the same samples from the same section the sediments record a negative excursion in 13 c carb values of 8 9 and in 13 c org values of 10 11 the presence of the conodont hindeodus parvus combined with the 13 c carb record enables correlation with the proposed global stratotype section at meishan this shows that the greenland section is the most expanded p tr section known collapse of the marine and terrestrial ecosystems took between 10 and 60 k y it took a further few hundred thousand years for the final disappearance of permian floral elements collapse of the terrestrial and marine ecosystems began at the same stratigraphic level and preceded the sharp negative excursion in the 13 c record

elevated trace element output in urine following acute volcanic gas exposure biological monitoring of exposure to gases and respirable particles is common in industry when urine or blood samples are analysed for elevated levels of various trace elements but this is almost unheard of in volcanology in this work 10 volunteers undertook 20 min of acute gas exposure downwind of fumaroles on white island new zealand pre and post exposure urine samples were analysed for aluminium arsenic rubidium and mercury elements which are known to be present in volcanic gases in order to test if any may be used as markers for gas exposure statistically significant p 0 025 post exposure increases in aluminium and rubidium excretion were seen indicating respiratory absorption during gas exposure no significant changes were observed in the analyses of arsenic and mercury we suggest that aluminium and possibly rubidium may be useful markers of exposure to other more hazardous gases to which volcanologists are exposed when working without respirators near fumaroles lava flows or other sources of volcanic gas

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

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

carbon and oxygen isotope records of permian brachiopods from relatively low and high palaeolatitudes climatic seasonality and evaporation

no abrupt change in redox condition caused the end permian marine ecosystem collapse in the east greenland basin abstract multiple observations have revealed that environmental disturbances may have been linked to the end permian mass extinction and delayed biotic recovery biogeochemical constraints on the temporal and spatial changes of oceanic redox chemistry during the permian triassic interval are essential to evaluate global significance of previous hypotheses and to improve our understanding of extinction and recovery processes to investigate redox ocean chemistry change associated with the end permian extinction and subsequent delayed biotic recovery we examine framboidal pyrites as well as sulfur isotopic compositions of pyrites from the east greenland basin the size distributions of framboidal pyrites in sediments from a continuous section across the permian triassic boundary reveal that sulfidic conditions in water columns were established about 0 7 m above the extinction event in the east greenland basin our detailed examination of framboidal pyrites challenges a leading hypothesis that euxinia in the photic zone caused the end permian ecosystem collapse we identify several positive and negative s isotopic shifts before and after the extinction event and demonstrate that a positive s isotopic shift is not indicative of an abrupt change of redox chemistry in water columns in contrast to previous claims the integration of isotope and framboidal pyrite data provides a nearly continuous record of ocean chemistry evolution and new insights into the end permian extinction and delayed biotic recovery in the east greenland basin

early triassic induan olenekian conodont biostratigraphy global anoxia carbon isotope excursions and environmental perturbations new data from western australian gondwana the early triassic induan olenekian stage boundary dienerian smithian sub stage boundary has been identified at a depth of 2719 25m in the petroleum exploration well senecio 1 located in the northern perth basin western australia conodont faunas represent three conodont zones in ascending order the neospathodus dieneri zone the neospathodus waageni eowaageni zone and the neospathodus waageni waageni zone the induan olenekian dienerian smithian boundary is placed at the base of the neospathodus waageni eowaageni zone equivalent to the first appearance of neospathodus ex gr waageni utilised elsewhere and adopted by the iugs ics triassic subcommission to define the base of the olenekian bulk kerogen 13c carbon isotopes define a positive peak of c 4 per mille that essentially coincides with the induan olenekian boundary as seen in proposed global stratotype sections and points gssps in south china and spiti india demonstrating the global utility of this level for correlation an anoxic zone is recognised in the lower part of the senecio 1 core and the upper limit of this zone is dated as late induan late dienerian temporal and spatial mapping of marine anoxia and dysoxia globally demonstrates that pulses of dysoxia anoxia affected shallow marine zones at different times in different locations dysoxia anoxia in the shallow marine environment appeared in the latest permian at the extinction level later than in the deep marine environment and appears to be largely restricted to the induan griesbachian and dienerian and early olenekian smithian temporally and geographically restricted upwelling of an oxygen minimum zone into the ocean surface layer due to environmental perturbations including extreme global warming increased terrestrial chemical weathering intensity and continental erosion sea level rise and changes in marine nutrient inventories and productivity rates is interpreted as a likely cause of observed variation in shallow marine dysoxia anoxia in the early triassic

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

two distinct episodes of marine anoxia during the permian triassic crisis evidenced by uranium isotopes in marine dolostones abstract the end permian mass extinction epme ca 251 94 ma is the most severe mass extinction in the geological record detailed paleobiological investigations show a very rapid epme event and recently published 238u data show a large negative excursion and thus a massive shift to globally expanded anoxia at the main extinction phase in the latest permian the negative shift in 238u is in correlation with a globally characterized negative 13c excursion near the permian triassic boundary ptb in some highly expanded ptb carbonate sections however there are two distinct negative 13c excursions whereas uranium isotopes 238u from such sections have not yet been examined leaving a gap in the understanding of the global perturbations of marine redox conditions immediately following the epme here we present a new 238u study of syn depositional dolostones from a well characterized and highly expanded drill core which recorded two pronounced negative 13c excursions across the ptb from the carnic alps austria this drill core extends 331 meters across the ptb and provides a unique opportunity to explore the detailed timing duration and extent of marine redox chemistry changes before during and immediately after the epme our new 238u record shows two negative shifts which are correlated with the two negative 13c excursions the first negative 238u excursion preceding the epme confirms the recently published 238u records from across the epme and support that syndepositional marine dolostones can record 238u trends of seawater similar to that of limestones modeling of uranium isotope cycling in the latest permian and earliest triassic oceans suggests two distinct stages of expanded marine anoxia separated by a brief interval 100 kyr of reoxygenation across the ptb the first anoxic episode lasted for 60 kyr while anoxic seafloor area expanded to cover 18 of the entire seafloor coeval with the main epme horizon agreeing with marine anoxia as a proximate kill mechanism for the epme the second anoxic event was less intense compared to the first anoxic pulse but sustained for a longer duration a global modeling of coupled c p and u cycles show that two pulses of volcanic carbon injection that drives global warming and increased phosphorus weathering rate can reasonably reproduce our data to match two phases of anoxia the model also demonstrates that the loss of terrestrial vegetation in the epme is crucial to generating an intervening interval of oxygenated ocean our new study adds to a growing body of evidence that the global marine redox conditions underwent rapid oscillations during the epme event and continued afterward which may have played a central role in delaying the marine ecosystem recovery in the early triassic

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

sulfur isotopic evidence for chemocline upward excursions during the end permian mass extinction the latest permian was a time of major change in ocean chemistry accompanying the greatest mass extinction of the phanerozoic to examine the nature of these changes samples from two well studied marine sections that span the permian triassic boundary have been analyzed the meishan and shangsi sections located in southern china isotopic analysis of the carbonate associated sulfate in these samples provides a detailed record of several isotopic shifts in 34scas approaching and across the ptb ranging from 30 to 15 vcdt with repeated asynchronous fluctuations at the two locations we interpret the patterns of isotopic shifts in conjunction with other data to indicate a shallow unstable chemocline overlying euxinic deep water which periodically upwelled into the photic zone these chemocline upward excursion events introduced sulfide to the photic zone stimulating a bloom of phototrophic sulfur oxidizing bacteria we hypothesize that elemental sulfur globules produced by these organisms and 34s depleted pyrite produced in the euxinic water column were deposited in the sediment later oxidation led to incorporation as cas this created the large changes to the 34scas observed in the latest permian at these locations

the permian triassic boundary at nhi tao vietnam evidence for recurrent influx of sulfidic watermasses to a shallow marine carbonate platform the permian triassic boundary at nhi tao cao bang province vietnam was sampled in a 7 5 m thick outcrop section at high resolution 5 cm intervals for chemostratigraphic and magnetic susceptibility analysis the section consists entirely of slightly argillaceous limestone representing shallow marine facies of the jinxi platform one of several large carbonate platforms within the nanpanjiang basin located on the southern margin of the south china craton upper permian strata beds 1 7 are mainly dark gray cherty fossiliferous wackestones and packstones containing a diverse open marine fauna whereas uppermost permian and lower triassic strata beds 9 and higher are medium gray calcimicrobial framestones containing rare macrofossils these facies are separated by a 12 cm thick oolitic pisolitic grainstone bed 8 that coincides with the disappearance of most late permian faunal elements as well as with the first appearance of various geochemical anomalies that continue into the lower triassic part of the section this late permian event horizon is characterized by 1 an abrupt decline in total organic carbon to near zero values 2 the onset of a sustained decline in carbonate 13c and 3 the first of eight concentration peaks in pyrite sulfur significantly each sulfide peak is associated with lower pyrite 34s values as well as with the onset of a negative carbonate 13c excursion or the acceleration of an excursion already in progress these chemostratigraphic relationships are consistent with multiple episodes of upwelling of sulfidic 34s and 13c depleted deep ocean waters onto the jinxi platform the first upwelling event was the most intense and caused a drastic reduction in primary productivity and the demise of the late permian fauna subsequent episodes were less intense but may have contributed to a delay in recovery of early triassic marine ecosystems a ten fold increase in magnetic susceptibility in bed 9 may record the influx of fine detrital particles following destruction of terrestrial ecosystems and massive soil erosion the terrestrial signal of the end permian catastrophe thus follows the marine signal with a 12 cm lag which may reflect the time of transit of soil derived particles across the nanpanjiang basin suggesting that the marine and terrestrial crises in the nhi tao region occurred more or less synchronously these observations suggest a model in which renewal of global ocean overturn followed a prolonged interval of deep ocean stagnation during the late permian with upwelling intensity modulated by short term 20 kyr climate cyclicity

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

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

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

high frequency fluctuations in redox conditions during the latest permian mass extinction abstract new high resolution geochemical and sedimentological data from fiskegrav east greenland reveal fluctuations in marine redox conditions associated with the final disappearance of bioturbating organisms during the latest permian mass extinction lpme sedimentological observations imply a transgressive episode and associated geochemical evidence for decreasing oxygen availability and the establishment of persistently ferruginous fe 2 rich conditions implies the shoreward migration of oxygen deficient waters the long term decline in dissolved oxygen do availability could have been exacerbated by increasing water temperatures reducing the solubility of oxygen and promoting thermal stratification mixing of the water column could have been further inhibited by freshwater influxes that could have generated salinity contrasts that reinforced thermal stratification enhanced runoff could also have increased the delivery of nutrients to the marine shelf stimulating biological oxygen demand bod during the transition to persistently ferruginous conditions we identify intervals of intermittent benthic meiofaunal recolonization events that we attribute to small transient increases in do availability the mechanism controlling these fluctuations remains speculative but given the possible centennial to millennial scale frequency of these changes we hypothesise that the mid latitude setting of fiskegrav during the late permian was sensitive to changes in atmospheric circulation patterns which may have influenced local precipitation and intermittently modulated some of the processes promoting anoxia

framboidal pyrite evidence for persistent low oxygen levels in shallow marine facies of the nanpanjiang basin during the permian triassic transition abstract previous studies suggested that anoxia was a causal factor in the end permian mass extinction epme marked by abrupt enrichment of pyrite framboids in the post epme microbialites of the earliest triassic on shallow platforms and that this dysoxic anoxic phase followed a time of well oxygenated seafloors here we report persistent dysoxia throughout the latest permian and euxinia just before the epme based on a new redox history reconstruction study using framboidal pyrite size distribution as well as sulfur isotopic compositions of pyrites from the taiping section on the pingguo platform in the nanpanjiang basin in china further we show that the epme was followed here by rapid oxygenation not an anoxic incursion this revised redox history might be an unusual localized phenomenon when compared to other platforms or it could be solid sedimentary evidence for redox oscillations outside the bioclast enriched photic zone which broadens our understanding of terrestrial marine ecosystem interactions before and during the epme

proxy evidence from the gartnerkofel 1 core carnic alps austria for hypoxic conditions in the western tethys during the end permian mass extinction event abstract the most severe mass extinction in the phanerozoic in the latest permian period 251 9 ma has been attributed to environmental effects related to the massive coeval siberian flood basalt eruptions a potential causal link between the eruptions and the marine extinctions arises from lethal global warming from greenhouse gas emissions and the resulting development of widespread hypoxic conditions in the warm oceans the 331 m gartnerkofel 1 core carnic alps austria penetrated the permian triassic boundary interval in a western tethys shallow carbonate ramp setting we calculated u th ratios and element enrichment factors for u cr v co and ni using the previously published raw elemental data from the core these redox sensitive proxy calculations provide evidence for an 60 ky long episode of anoxic to euxinic ocean conditions in the shallow western tethys at the time of the abrupt end permian mass extinction epme subsequent fluctuating dysoxic conditions were coincident with a negative excursion of 13ccarb that is estimated to have lasted 450 ky in the earliest triassic at the gk 1 site these findings in a high deposition rate section support previous reports of widespread anoxia in the western tethys and in the oceans in general coincident with the epme and its aftermath

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