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

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

campanian bolivinoides and microfacies from the la luna formation western venezuela abstract tres esquinas the upper member of the la luna formation a 1 3 m thick condensed sequence composed of glauconitic phosphorite signals the commencement of the late cretaceous regression in western venezuela this is the last of a series of thin phosphatic beds the others non glauconitic occurring in the upper la luna formation in the state of merida the presence of bolivinoides culverensis restricts these phosphatic beds to the late santonian early campanian with the tres esquinas member assigned to the globotruncanita elevata globotruncana ventricosa zones bolivinoides sp cf b sirticus is also commonly found in these beds although no bolivinoides have been detected in the tres esquinas member in the state of tachira to the west the non glauconitic phosphate bed informally named capa ii as well as the 15 m thick ftanita de tachira member which underlies the tres esquinas member and separates it from capa ii contain bolivinoides culverensis as well as bolivinoides cf b sirticus this occurrence combined with the assignation of the base of the overlying colon formation to the globotrucana aegyptiaca zone suggests a late campanian age for the member in this area and implies that the member is diachronous on the basis of lithology mineralogy foraminiferal content and degree of bioturbation six microfacies and one sub microfacies are identified the microfacies of the phosphatic limestones containing bolivinoides spp are notably different in the two states

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

anomalously diverse early triassic ichnofossil assemblages in northwest pangea a case for a shallow marine habitable zone early triassic trace fossil assemblages from the northwest margin of pangea record a diverse suite of postextinction infauna these ichnofossil assemblages occurred within well oxygenated shallow marine refuges in a panthalassa ocean otherwise characterized by widespread anoxia we propose an environmentally controlled model for their distribution in which wave aeration enhanced by frequent storms gave rise to an optimal zone for benthic colonization within this habitable zone extinction pressures were ameliorated and postextinction recovery duration was minimized

global coal gap between permian triassic extinction and middle triassic recovery of peat forming plants early triassic coals are unknown and middle triassic coals are rare and thin the early triassic coal gap began with extinction of peat forming plants at the end of the permian ca 250 ma with no coal known anywhere until middle triassic 243 ma permian levels of plant diversity and peat thickness were not recovered until late triassic 230 ma tectonic and climatic explanations for the coal gap fail because deposits of fluctuating sea levels and sedimentary facies and paleosols commonly found in coal bearing sequences are present also in early triassic rocks nor do we favor explanations involving evolutionary advances in the effectiveness of fungal decomposers insects or tetrapod herbivores which became cosmopolitan and much reduced in diversity across the permian triassic boundary instead we favor explanations involving extinction of peat forming plants at the permian triassic boundary followed by a hiatus of some 10 m y until newly evolved peat forming plants developed tolerance to the acidic dysaerobic conditions of wetlands this view is compatible not only with the paleobotanical record of extinction of swamp plants but also with indications of a terminal permian productivity crash from delta sup 13 c sub org and total organic carbon of both nonmarine and shallow marine shales 205 refs 3 figs more 3 tabs less

ultra shallow marine anoxia in an early triassic shallow marine clastic ramp spitsbergen and the suppression of benthic radiation lower triassic marine strata in spitsbergen accumulated on a mid to high latitude ramp in which high energy foreshore and shoreface facies passed offshore into sheet sandstones of probable hyperpycnite origin more distal facies include siltstones shales and dolomitic limestones carbon isotope chemostratigraphy comparison allows improved age dating of the boreal sections and shows a significant hiatus in the upper spathian two major deepening events in earliest griesbachian and late smithian time are separated by shallowing upwards trends that culminated in the dienerian and spathian substages the redox record revealed by changes in bioturbation palaeoecology pyrite framboid content and trace metal concentrations shows anoxic phases alternating with intervals of better ventilation only dienerian early smithian time witnessed persistent oxygenation that was sufficient to support a diverse benthic community the most intensely anoxic usually euxinic conditions are best developed in offshore settings but at times euxinia also developed in upper offshore settings where it is even recorded in hyperpycnite and storm origin sandstone beds an extraordinary facet of spitsbergen s record the euxinic phases do not track relative water depth changes for example the continuous shallowing upwards from the griesbachian to lower dienerian was witness to several euxinic phases separated by intervals of more oxic bioturbated sediments it is likely that the euxinia was controlled by climatic oscillations rather than intra basinal factors it remains to be seen if all the anoxic phases found in spitsbergen are seen elsewhere although the wide spread of anoxic facies in the smithian spathian boundary interval is clearly a global event

the influence of lateral spreading on settlements beneath a fill the discrepancy between calculated consolidation settlements and measured settlements under a 3 8 m high section of an earth embankment is investigated in this paper a conventional one dimensional analysis underestimated the observed settlement by 40 a two dimensional finite element analysis was carried out to assess the effects of lateral spreading on vertical movements and the results were in close agreement with the measured values key words case history consolidation finite element analysis settlement

quasi planar laminated sandstone beds of the lower cretaceous bootlegger member north central montana evidence of combined flow sedimentation abstract lower shoreface to shallow shelf strata of the bootlegger member of the lower cretaceous blackleaf formation are characterized by interbedded sandstone and mudstone sandstone beds are characterized by a peculiar planar lamination showing a subtle although perceptible undulation spacing to height ratios of the undulation are generally 100 or more typically the undulation shows no evidence of lateral accretion but only vertical aggradation and as a result most beds consist of a single laminaset aspects of quasi planar laminated beds indicate single event storm sedimentation and paleocurrent data indicate offshore sediment transport by its sedimentary characteristics and its similarity with a bed configuration generated in un experimental wave duct quasi planar lamination is produced by high energy combined flows this style of stratification should be common in the shallow marine stratigraphic record and its recognition should aid in interpreting high energy combined flow depositional events

sedimentation in deep sea lobe elements implications for the origin of thickening upward sequences the frequency and origin of thickening upward packages in the sediments of deep sea environments has been a topic of much recent debate excellent bed scale exposures in the carboniferous ross formation western ireland allow single surfaces to be traced laterally and the detailed architecture of whole packages to be evaluated using multiple vertical logs the deposits comprise architectural elements including bed sets lobe elements and composite lobes with the lobe elements being arranged in thickening upward depositional packages results show that these packages are the result of the progradation of each lobe element whereby each package records a vertical trend from distal to proximal deposits accompanied by an increasing frequency of megaflutes and ultimately the development of broad erosional surfaces we propose a six stage model for lobe element evolution that documents successive phases of deposition sediment bypass erosion and lobe abandonment this new model provides a mechanism for lobe element switching and explains the development of thickening upward successions this allows the re examination of existing process models for these sedimentary packages in deep sea sediments

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

new early triassic bryozoa trepostomata from spitsbergen with some remarks on the stratigraphy of the investigated horizons new trepostomatous bryozoan species paralioclema winsnesi sp nov paralioclema mariaholmensis sp nov and paralioclema sp cf mariaholmensis are described from the lower triassic succession of spitsbergen the investigated bryozoan faunas are associated with coarse sandstones calcareous siltstones and shelly limestones the bryozoan colonies are mostly well preserved in situ and show limited evidence of transportation some zoarial fragments show bioerosion the conodont species neogondolella elongata ellisonia triassica neospathodus dieneri and neospathodus svalbardensis extracted from the investigated horizons are dienerian smithian in age

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

black shales on the basin margin a model based on examples from the upper jurassic of the boulonnais northern france abstract organic rich shales were deposited during two phases of relative sea level rise in the kimmeridgian late jurassic basin margin sections of the boulonnais n france pyrite framboid analysis indicates that bottom waters were euxinic during substantial periods of organic rich shale formation and th u ratios and degree of pyritisation of fe suggest severe oxygen restriction whilst palaeoecological and sedimentological evidence suggests that seafloor oxygenation events were frequent interbedded hummocky cross stratified sandstones indicate deposition above storm wave base correlation of lateral facies changes reveals that the black shales record deposition beneath a nearshore zone of oxygen poor waters that contracted in lateral extent during parasequence formation the boulonnais black shales are similar to other varieties of transgressive black shale in that they are developed upon surfaces of marine starvation but they differ in that they pass down dip into better oxygenated facies they are therefore classified as transgressive nearshore tn black shales that do not record the feather edge of basinal conditions deposition is interpreted to have occurred beneath a small volume of sub thermocline bottom waters that were readily de oxygenated whilst anoxia was less readily developed in more offshore settings due to the greater volume of sub thermocline water why such conditions should pertain only during initial stages of base level rise remains obscure

a new high resolution stratigraphic and palaeoenvironmental record spanning the end permian mass extinction and its aftermath in central spitsbergen svalbard abstract research on the permian triassic boundary ptb along the northern margins of pangaea exposed today in the arctic region has been heavily reliant on field observations where data resolution was consequently determined by outcrop condition and accessibility core drilling in central spitsbergen allowed for a near complete recovery of two 90 m cores through the ptb analyses of the core and nearby outcrops include stratigraphic logging and sampling xrf scanning petrography biostratigraphy isotope geochemistry and geochronology the first appearance datum fad of h parvus in svalbard places the base of the triassic ca 4 m above the base of the vikinghogda formation and ca 2 50 m above the end permian mass extinction epme and its associated sharp negative 13c the ptb therefore falls within the reduviasporonites chalastus assemblage zone in svalbard precise u pb tims dating of two zircon crystals in a tephra layer just above the first documented hindeodus parvus in svalbard gives an age of 252 13 0 62 ma high resolution palaeoenvironmental proxies including si kcps kilo counts per second zr rb k ti fe k and v cr indicate a transition towards a more arid climate in the earliest triassic contemporaneous with prolonged bottom water dysoxic anoxic conditions following an increase in volcanic activity in the late permian statistical analysis of zr rb k ti and v cr elemental ratios suggests that the system was impacted by long eccentricity 400 kyr cyclicity the 13c excursion in organic carbon 13corg record signals a large negative carbon isotope excursion cie associated with the mass extinction event but also records a second smaller negative cie ca 22 m above this interval this younger 13corg excursion correlates to similar cies in the dienerian late induan records of other sections notably in the tethys ocean which have been interpreted as recording a small biotic crisis during the post extinction recovery evidence of this negative cie in spitsbergen suggests that the dienerian crisis may have been global in extent the negative 13corg values are associated with evidence for dysoxia or anoxia in the core and the occurrence of tephra layers in the same interval suggests a possible connection between the dienerian crisis and a discrete episode of volcanic activity

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

proliferation of early triassic wrinkle structures implications for environmental stress following the end permian mass extinction lower triassic strata in the western united states and northern italy have yielded the first reported occurrence of microbially mediated wrinkle structures in shallow subtidal siliciclastic paleoenvironments since the cambrian we hypothesize that wrinkle structures formed under reduced infaunalization conditions during the aftermath of the end permian mass extinction these wrinkle structures occur in siliciclastic sedimentary rocks in association with hummocky cross stratification and in some cases trace fossils such as asteriacites rhizocorallium planolites and gyrochorte that indicate a subtidal paleoenvironment wrinkle structures were found in the campil member in the werfen formation of northern italy and in the virgin limestone member of the moenkopi formation and the upper member of the thaynes formation exposed in the western united states the presence of wrinkle structures is likely related to a unique taphonomic window that allowed for the preservation of these delicate features on storm dominated siliciclastic shelves wrinkle structures commonly formed in a variety of subtidal paleoenvironments during the proterozoic cambrian but thereafter became restricted to intertidal supratidal and deep sea environments this restriction has been attributed to the increase in infaunalization of metazoans following the cambrian radiation the proliferation of wrinkle structures in subtidal settings during the early triassic suggests that infaunal bioturbation was reduced after the end permian mass extinction and that this reduction lasted for millions of years

the end permian mass extinction and its aftermath on an equatorial carbonate platform insights from ichnology terra nova 22 195 202 2010 abstract a semi quantitative analysis of the endobenthic activity across the permo triassic boundary ptb was carried out on a 445 m thick well core interval from the persian gulf by logging the degree of bioturbation trace fossil distribution and ichnodiversity id this analysis enables for the first time the evaluation of recovery of endobenthic organisms after the end permian mass extinction by direct comparison of post extinction lower triassic with pre extinction upper permian units the results indicate that the studied shallow marine carbonate platform within an equatorial setting acted as oxygenated refugee for the biotic recovery traces of suspension and deposit feeders reappear simultaneously shortly after the extinction event but are reduced in size macroborings so far unknown from the lower triassic occur where suitable firm or hard substrate was available recovery took place in two phases early induan 50 pre extinction id and 20 30 bioturbation and late induan 75 id and almost 90 bioturbation re established

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

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

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

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

high amplitude redox changes in the late early triassic of south china and the smithian spathian extinction abstract the early triassic was a time of remarkably high temperatures large carbon cycle perturbations and episodes of widespread ocean anoxia the sediments in the nanpanjiang basin of south china provide superb opportunities to examine the sedimentary response to these extreme conditions especially during the crisis interval at the smithian spathian s s boundary we have investigated a deep water section at jiarong and a shallower water section at mingtang these contain a range of facies including black shales micritic limestone units and rudaceous carbonate event beds that include flat pebble conglomerates and breccia debrites that bear similarities to the hybrid event beds seen in clastic turbidite successions redox proxies pyrite framboids and trace metals reveal that widespread anoxia in the late smithian persisted into the novispathodus pingdingshanensis zone of the early spathian before a sharp transition to highly oxygenated griotte facies red marine strata in the icriospathodus collinsoni zone that records an oxic rebound benthic faunas are locally common but of low diversity and dominated by thin shelled bivalves and ostracodes with small foraminifers and exceptionally rare fish remains bioturbation was intense only in the early middle spathian i collinsoni conodont zone griotte facies anoxia and extremely high temperatures probably played a role in severely restricting the abundance of fish and the small sizes of marine invertebrates at this time the presence of ooids and seafloor fan cements in our study sections indicates highly saturated conditions rather than acidification at the end of the smithian

pyrite framboid study of marine permian triassic boundary sections a complex anoxic event and its relationship to contemporaneous mass extinction size analysis of pyrite framboids has been undertaken on epicontinental permian triassic boundary sections throughout the world in order to evaluate the intensity and duration of anoxia mid paleolatitude sections from the margins of the boreal spitsbergen greenland and neotethyan oceans western australia reveal intense anoxia throughout the permian triassic boundary interval with euxinic conditions frequently developing and dysoxia encountered even in relatively shallow water settings above storm wave base at equatorial paleolatitudes weakly oxygenated dysoxic conditions are widely developed in a broad range of water depths including those shallow enough to produce oolite deposition although euxinia was rare western and eastern tethyan locations re veal a complex and unstable redox history anoxia in the hindeodus praeparvus zone was replaced by oxygenated facies in the permian triassic boundary interval h changxingensis to h parvus zones oxygen poor deposition returned during the succeeding isarcicella isarcica zone the more persistent and intense development of oxygen restriction in cooler water mid paleolatitude sections argues against warming and dissolved oxygen decline as the key cause of permian triassic bound ary anoxia in higher paleolatitudes the ben thic invertebrate extinctions occurred during a prolonged phase of oxygen poor deposition while in equatorial tethyan locations benthic losses occurred at the end of the fi rst anoxic phase in the late h praeparvus zone

comparison of field consolidation with laboratory and in situ tests settlement calculations for an earth embankment resting on soft compressible fraser river delta sediments were made from laboratory consolidation tests and in situ tests using a piezocone and a flat dilatometer the calculated values were compared with measured settlements there was rather good agreement among the three methods of calculation but the actual settlement was about 60 greater than the average calculated value calculated rates of settlement are also compared with observed values key words consolidation settlements piezocone dilatometer in situ tests constrained modulus pore water pressure settlement rate

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

recurrent early triassic ocean anoxia the early triassic record from the smithian stratotype shows that the organic carbon isotope record from northwest pangea closely corresponds to major fluctuations in the inorganic carbon records from the tethys indicating truly global perturbations of the carbon cycle occurred during this time geochemical proxies for anoxia are strongly correlated with carbon isotopes whereby negative shifts in 13 c org are associated with shifts to more anoxic to euxinic conditions and positive shifts are related to return to more oxic conditions rather than by a delayed or prolonged recovery the early triassic is better characterized by a series of aborted biotic recoveries related to shifts back to ocean anoxia potentially driven by recurrent volcanism

initiation of turbidity currents outcrop evidence for eocene hyperpycnal flow turbidites abstract the most widely used although not as widely documented explanation for initiation of turbidites is the conversion of catastrophic sediment failures into turbidites such instantaneous sediment failures generate short lived surge type flows that deposit turbidite beds described as bouma sequences in this communication we present data from the eocene central basin of spitsbergen that shows turbidite systems that are volumetrically dominated by thick ungraded and laminated sandy turbidite beds deposited by gradual aggradation from sustained flows sustained flows are long lived and more or less continuous they can be generated by a variety of mechanisms e g 1 instability during volcanic eruptions and the consequent remobilisation of unconsolidated material 2 seismically triggered subaerial sliding within the drainage 3 storm surges 4 retrogressive slope failure 5 breaching and 6 hyperpycnal flows our database shows that in the eocene central basin the sustained flows were generated by hyperpycnal flows i e by direct river effluent the hyperpycnal flow turbidites have been recognized on the basis of 1 physical connection between fluvial and turbidite channels at the shelf edge 2 abundance of thick turbidite sandstone beds 3 sand prone nature of the turbidite systems 4 downslope changes of individual thick sandy turbidite beds and their collapsed pinch out segments 5 great abundance of continental material leaves coal fragments in turbidite beds 6 low abundance of associated slumped or debris flow beds and 7 the occurrence of turbidites in systematically accreted shelf margins these features strongly suggest that hyperpycnal flow generated by direct river effluent deposited significant number of turbidite beds in the documented slope and basin floor turbidite successions we also argue that the hyperpycnal flows are preferentially fed into the deepwater slopes beyond the shelf edge during the falling stage and lowstand of relative sea level the turbidite beds were studied in the context of seismic scale 1 15 km dip oriented outcrops by measuring detailed vertical sections following individual beds and packages of beds downslope for distances over 5 km lateral mapping and helicopter taken photomosaics

work as a criterion for determining in situ and yield stresses in clays discussion this is a discussion of a paper by the same title which appeared in vol 24 canadian geotechnical journal pp 549 564 the authors of the original paper are d e becker j h a crooks k been and m g jefferies

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

loss of the sedimentary mixed layer as a result of the end permian extinction abstract the end permian mass extinction resulted in the most dramatic degradation of marine bottom communities during the phanerozoic one result of this extinction was the long recognized extreme reduction in bioturbation of the early triassic seafloor several lines of evidence i e preferential preservation of epifaunal and very shallow tier infaunal trace fossils paucity of mid and deep tier trace fossils absence of mottled bioturbation textures dominance of cohesive substrates widespread occurrence of microbially induced sedimentary structures in open marine environments ecological composition of early triassic communities show that the reduction in bioturbation was so extreme that the sedimentary mixed layer was eradicated at an interregional scale for the only time since it was established in the early palaeozoic the consequences of this for ecosystem function and geochemical cycling must have been profound and yet they have received little consideration biogenic mixing of sediments is fundamental to geochemical cycling in extant marine ecosystems and it also governs ecologically limiting factors such as nutrient fluxes benthic primary production and availability of ecospace the collapse of biogenic sediment mixing during the early triassic must have affected geochemical properties of sediments and the seawater as reflected in the geologic record of the sulphur cycle additionally many of the proxies traditionally used to infer early triassic seawater anoxia may rather reflect poor sediment oxygenation arising from the extinction of bioturbators because of its impact on seawater and sediment chemistry the loss of the mixed layer may have been an important but hitherto little considered constraint on the recovery from the end permian mass extinction