terrestrial and marine extinction at the triassic jurassic boundary synchronized with major carbon cycle perturbation a link to initiation of massive volcanism mass extinction at the triassic jurassic tr j boundary occurred about the same time 200 ma as one of the largest volcanic eruptive events known that which characterized the central atlantic magmatic province organic carbon isotope data from the uk and greenland demonstrate that changes in flora and fauna from terrestrial and marine environments occurred synchronously with a light carbon isotope excursion and that this happened earlier than the tr j boundary marked by ammonites in the uk the results also point toward synchronicity between extinctions and eruption of the first central atlantic magmatic province lavas suggesting a causal link between loss of taxa and the very earliest eruptive phases the initial isotopic excursion potentially provides a widely correlatable marker for the base of the jurassic a temporary return to heavier values followed but relatively light carbon dominated the shallow oceanic and atmospheric reservoirs for at least 600 k y

anomalies in global carbon cycling and extinction at the triassic jurassic boundary evidence from a marine c isotope record this study investigates whether the end triassic biotic crisis was coupled with a perturbation of the marine c isotope budget the marine c isotope signature serves as a proxy of the marine carbon reservoir and ultimately of the global c cycle a continuous shallow water marine limestone succession from the western southern alps bergamasc alps northern italy provides information on the end triassic biotic crisis and on the evolution of the marine carbon reservoir across the triassic jurassic t j boundary the established carbonate c isotope curve is marked by a negative c isotope pulse coinciding with the disappearance of the end triassic benthic faunal assemblage and a widespread rhaetian carbonate platform drowning event the negative spike is followed by a positive c isotope excursion starting at the palynological t j transition the negative c isotope pulse may have resulted from the sudden release of gas hydrates the positive isotope excursion records a global change in organic carbon burial rates probably in response to elevated atmospheric co2 levels at a time of massive volcanic activity in the central atlantic magmatic province high co2 levels were responsible for the end triassic biocalcification crisis carbonate platform collapse and possibly the sudden release of methane from gas hydrate

testing the terrestrial δ13c cretaceous paleogene k pg chemostratigraphic marker abstract multiple 1 13 c isotopic excursions measured across the cretaceous paleogene k pg boundary in an iridium bearing stratigraphic section from mud buttes north dakota usa fail to demonstrate an unambiguous chemostratigraphic signal for the extinction results of two sample kolmogorov smirnov tests using 13 c records for the mud buttes section as well as five other published k pg sections from montana north dakota wyoming and canada all of which report a 1 0 to 2 8 chemostratigraphic marker at or just above the extinction demonstrate that it may not be possible to distinguish a statistically meaningful isotopic shift to lower 13 c values at the boundary in the context of background variations carbon isotopes as terrestrial chemostratigraphic markers of the k pg extinction boundary are thus of limited utility

duration of and decoupling between carbon isotope excursions during the end triassic mass extinction and central atlantic magmatic province emplacement abstract changes in 13 c carb and 13 c org from marine strata occur globally in association with the end triassic mass extinction and the emplacement of the central atlantic magmatic province camp during the break up of pangea as is typical in deep time the timing and duration of these isotopic excursions has remained elusive hampering attempts to link carbon cycle perturbations to specific processes here we report 13 c carb and 13 c org from late triassic and early jurassic strata near levanto peru where intercalated dated ash beds permit temporal calibration of the carbon isotope record both 13 c carb and 13 c org exhibit a broad positive excursion through the latest triassic into the earliest jurassic the first order positive excursion in 13 c org is interrupted by a negative shift noted in many sections around the world coincident with the extinction horizon our data indicate that the negative excursion lasts 85 25 kyrs longer than inferred by previous studies based on cyclostratigraphy a 260 80 kyr positive 13 c org shift follows during which the first jurassic ammonites appear the overall excursion culminates in a return to pre perturbation carbon isotopic values over the next 1090 70 kyrs via chronologic isotopic and biostratigraphic correlation to other successions we find that 13 c carb and 13 c org return to pre perturbation values as camp volcanism ceases and in association with the recovery of pelagic and benthic biota however the initiation of the carbon isotope excursion at levanto predates the well dated camp sills from north america indicating that camp may have started earlier than thought based on these exposures or that the onset of carbon cycle perturbations was not related to camp

no causal link between terrestrial ecosystem change and methane release during the end triassic mass extinction profound changes in both marine and terrestrial biota during the end triassic mass extinction event and associated successive carbon cycle perturbations across the triassic jurassic boundary t j 201 3 ma have primarily been attributed to volcanic emissions from the central atlantic magmatic province and or injection of methane here we present a new extended organic carbon isotope record from a cored t j boundary succession in the danish basin dated by high resolution palynostratigraphy and supplemented by a marine faunal record correlated with reference c isotope and biotic records from the uk it provides new evidence that the major biotic changes both on land and in the oceans commenced prior to the most prominent negative c isotope excursion if massive methane release was involved it did not trigger the end triassic mass extinction instead this negative c isotope excursion is contemporaneous with the onset of floral recovery on land whereas marine ecosystems remained perturbed the decoupling between ecosystem recovery on land and in the sea is more likely explained by long term flood basalt volcanism releasing both so2 and co2 with short and long term effects respectively

oceanic primary productivity and dissolved oxygen levels at the cretaceous tertiary boundary their decrease subsequent warming and recovery thirty six different geochemical and foraminiferal analyses were conducted on samples collected at closely spaced intervals across the cretaceous tertiary k t boundary exposed at caravaca spain a rapid reduction in the gradient between 13c values in fine fraction carbonate and benthic foraminiferal calcite and a decrease in the abundance of phosphorus a proxy for organic carbon and calcium were recorded in sediments 0 0 5 cm above the k t boundary these trends imply that an abrupt mass mortality occurred among pelagic organisms leading to a significant reduction in the flux of organic carbon to the seafloor in addition variations in sulfur isotope ratios the hydrocarbon generating potential of kerogen measured as the hydrogen index and foraminiferal indices of dissolved oxygen level all imply that a rapid decrease in dissolved oxygen was coincident with the 13c event evidence of the low oxygen event has also been recognized in japan and new zealand suggesting that intermediate water oxygen minima were widely developed during earliest danian time a threefold increase in the kaolinite illite ratio and a 1 2 decrease in 18o carbonate fine fraction were recorded in the basal 0 1 2 cm of danian age sediments these trends suggest that atmospheric warming and an increase in surface water temperature occurred 0 3 kyr after the 13c event recovery in the difference between 13c values in the carbonate fine fraction and in benthic foraminiferal calcite as well as increases in phosphorus and calcium contents occur at the base of planktonic foraminiferal zone pla implying that an increase in primary productivity commenced some 13 kyr after the k t boundary tables a1 a3 are available on diskette or via anonymous ftp from kosmos agu org directory apeno username anonymous password guest diskette may be ordered from american geophysical union 2000 florida avenue n w washington dc 20009 or by phone at 800 966 2481 15 00 payment must accompany order

development of an equatorial carbonate platform across the triassic jurassic boundary and links to global palaeoenvironmental changes musandam peninsula uae oman abstract the triassic jurassic boundary is marked by one of the big five mass extinctions of the phanerozoic this boundary event was accompanied by several carbon cycle perturbations potentially induced by the opening of the central atlantic and associated volcanism and accompanied by an ocean acidification event continuous carbonate successions covering this interval of environmental change are however rare here data from a shallow marine equatorial mixed carbonate siliciclastic succession is presented that was studied on a regional scale four sections that are 48 km apart were examined on the musandam peninsula united arab emirates and sultanate of oman the system was analysed for its sedimentology vertical and lateral facies changes and stable carbon and oxygen isotopes strontium isotope analysis was used to determine the position of the triassic jurassic boundary horizon the studied ramp experienced an episode of demise during the late triassic followed by a restricted microbialite dominated ramp containing large amounts of siliciclastic facies during the latest triassic the diverse carbonate factory revived and flourished across the triassic jurassic boundary no clear evidence for a biocalcification crisis or an ocean acidification event across the triassic jurassic boundary is visible lateral facies heterogeneities can be observed across the studied interval attributed to hydrodynamic activity including tropical storms crossing the extensive shelf area although evidence for synsedimentary tectonic activity is present the vertical stacking pattern is largely controlled by changes in relative sea level the refined chronostratigraphy accompanied by the detailed environment of deposition analysis allows for a refinement of the regional palaeogeography the neritic equatorial carbonate ramp has archived a negative carbon isotope excursion preceding the triassic jurassic boundary that has also been reported from other study sites the lack of evidence for a biocalcification crisis across the equatorial triassic jurassic boundary indicates that the tethys did not experience a distinct global acidification event

the triassic isotope record a variety of stable isotope measurements have been found useful in studying processes of environmental change measurements of d 13 c d 18 o d 34 s and 87 sr 86 sr all can provide infor mation about the conditions of the water column in which sediment deposition occurred but the most widely applied of these is d 13 c the carbon isotope record for the triassic system is a complex one a pronounced negative excursion begins below the base of the triassic system and continues into the basal triassic the succeeding 4 to 6 ma lower triassic interval is marked by isotopic instability with positive and negative excursions continuing through the basal middle triassic in contrast to the lower triassic most of the middle and upper triassic display relative isotopic stability with rising values of d 13 c likely reflecting environmental recov ery and increasing storage of organic carbon in terrestrial environments the uppermost triassic is marked by a pronounced negative excursion near the system boundary that has been linked to significant biotic turnover the causes of the various excursions remain under investigation particularly those at the system boundaries with outgassing during volcanic activity changes in productivity ocean anoxia and seafloor methane releases all suggested as mechanisms both for perturbing the global carbon cycle and for forcing biotic extinction

sudden productivity collapse associated with the triassic jurassic boundary mass extinction the end triassic mass extinction is one of the five most catastrophic in phanerozoic earth history here we report carbon isotope evidence of a pronounced productivity collapse at the boundary coincident with a sudden extinction among marine plankton from stratigraphic sections on the queen charlotte islands british columbia canada this signal is similar to though smaller than the carbon isotope excursions associated with the permian triassic and cretaceous tertiary events

the organic carbon isotopic and paleontological record across the triassic jurassic boundary at the candidate gssp section at ferguson hill muller canyon nevada usa we present new litho bio and chemostratigraphic data from the triassic jurassic t j boundary section at ferguson hill muller canyon nevada usa this section is a candidate for the base of the hettangian stage and thus the t j boundary our measurements yield a 19 m thickness for the muller canyon member of the gabbs formation we recognize the triassic jurassic boundary using the first appearance of agerchlamys and place it 9 6 m above the boundary between the muller canyon member and the subjacent mount hyatt member with the first occurrence of the ammonite psiloceras tilmanni occurring 0 9 m above this our organic carbon isotope record from this section shows two excursions toward lighter values one at the t j boundary and the second in the lower parts of the jurassic sunrise formation these results are significantly different from a prior report on light stable isotopes from this section

palaeontology slowed by sulphide the triassic jurassic period extinction marked a rapid turnover in the marine realm biomarkers in marine rocks suggest that the development of sulphidic conditions in the early jurassic delayed marine recovery

multiple sulfur isotopic evidence for a shallowly stratified ocean following the triassic jurassic boundary mass extinction the cause of the triassic jurassic tr j boundary biotic crisis one of the big five mass extinctions of the phanerozoic remains controversial in this study we analyzed multiple sulfur isotope compositions 33s 34s and 36s of pyrite and spy toc ratios in two tr j successions mariental mingolsheim from the european epicontinental seaway ees in order to better document ocean redox variations during the tr j transition our results show that upper rhaetian strata are characterized by 34s enriched pyrite low spy toc ratios and values of 33spy i e the deviation from the mass dependent array lower than that estimated for contemporaneous seawater sulfate suggesting an oxic suboxic depositional environment punctuated by brief anoxic events the overlying hettangian strata exhibit relatively 34s depleted pyrite high 33spy and spy toc values and the presence of green sulfur bacterial biomarkers indicate a shift toward to euxinic conditions the local development of intense marine anoxia thus postdated the tr j mass extinction which does not provide support for the hypothesis that euxinia was the main killing agent at the tr j transition sulfur and organic carbon isotopic records that reveal a water depth gradient i e more 34s 13c depleted with depth in combination with spy toc data suggest that the earliest jurassic ees was strongly stratified with a chemocline located at shallow depths just below storm wave base shallow oceanic stratification may have been a factor for widespread deposition of black shales a large positive shift in carbonate 13c values and a delay in the recovery of marine ecosystems following the tr j boundary crisis

a new rhaetian δ13corg record carbon cycle disturbances volcanism end triassic mass extinction ete abstract the links between large scale volcanism carbon cycle perturbations and the biotic crises at the end triassic extinction event ete are not well understood the ete seems to be marked by three carbon isotope excursions cies likely triggered by different eruptive phases of the central atlantic magmatic province camp these three cies appear to occur during the late rhaetian close to the triassic jurassic boundary tjb but the relative timing connecting the volcanism carbon perturbations and extinctions is still subject to debate resulting from i the difficulties in long distance biostratigraphic correlations of rhaetian successions due to the step like extinction pattern characterizing the ete and to the lack of globally correlatable key fossil group s across the system boundary ii the limit of coverage of available 13c profiles to the system boundary interval rather than the entire rhaetian iii the inherent difficulties in correlating cies without clear biostratigraphic markers here we present a 13corg curve from the lombardy basin which covers for the first time the entire rhaetian using this chemostratigraphy we propose two possible correlations option 1 and option 2 with other late rhaetian to early hettangian successions worldwide these two possible correlations rely on a combination of paleontological ammonoids pollens conodonts lithostratigraphic and geochemical constraints option 2 in particular has important implications for the causality and geochronology of the ete events by suggesting that the sharp negative peak usually considered to be the initial cie in the lombardy might represent a carbon perturbation within the negative trend of the main cie this implies that a reconsideration of the succession of biotic events occurring during this time interval is required

the late triassic extinction at the norian rhaetian boundary biotic evidence and geochemical signature abstract the latest triassic was an interval of prolonged biotic extinction culminating in the end triassic extinction ete the ete is now associated with a perturbation of the global carbon cycle just before the end of the triassic that has been attributed to the extensive volcanism of the circum atlantic magmatic province camp however we attribute the onset of declining latest triassic diversity to an older perturbation of the carbon cycle 13corg of global extent at or very close to the norian rhaetian boundary nrb the nrb appears to be the culmination of stepwise biotic turnovers that characterize the latest triassic and includes global extinctions of significant marine and terrestrial fossil groups these biotic events across the nrb have been largely under appreciated yet together with a coeval disturbance of the carbon cycle were pivotal in the history of the late triassic here we present new and published 13corg data from widespread sections italy greece odp australia new zealand usa canada these sections document a previously unknown perturbation in the carbon cycle of global extent that spanned the nrb the disturbance extended across the panthalassa ocean to both sides of the pangaean supercontinent and is recorded in both the northern and southern hemispheres the onset of stepwise late triassic extinctions coincides with carbon perturbation 13corg at the nrb indicating that a combination of climatic and environmental changes impacted the biota at a global scale the nrb event may have been triggered either by gas emissions from the eruption of a large igneous province pre dating the nrb by a bolide impact of significant size or by some alternative source of greenhouse gas emissions as yet it has not been possible to clearly determine which of these trigger scenarios was responsible the evidence is insufficient to decisively identify the causal mechanism and merits further study

sedimentary organic matter characterization of the triassic jurassic boundary gssp at kuhjoch austria abstract the triassic jurassic t j boundary interval coincides with enhanced extinction rates in the marine realm and pronounced changes in terrestrial ecosystems on the continents it is further marked by distinct negative excursions in the 13corg and 13ccarb signature that may represent strong perturbations of the global carbon cycle we present integrated geochemical stable isotope and palynological data from the kuhjoch section the global boundary stratotype section and point gssp for the base of the jurassic northern calcareous alps austria we show that the initial carbon isotope excursion cie coinciding with the marine extinction interval and the formation of black shales in the western tethys eiberg basin is marked by only minor changes in kerogen type which is mainly of terrestrial origin increased total organic carbon toc concentrations of 9 at the first half of the initial cie coincide with hydrogen index hi values of over 600 mg hc g toc the high correlation with r2 0 93 between hi values and terrestrial cheirolepidiaceaen conifer pollen suggests a terrestrial source for the hydrogen enriched organic compounds the lack of major changes in source of the sedimentary organic matter suggests that changes in the 13corg composition are genuine and represent true disturbances of the global c cycle the sudden decrease in total inorganic carbon tic concentrations likely represents the onset of a biocalcification crisis it coincides with a 4 5 negative shift in 13corg values and possibly corresponds to the onset of camp related volcanic activity the second half of the initial cie is marked by the dramatic increase of green algae remains in the sediment the simultaneous increase of the corg ntot ratio suggests increased marine primary production at the final stage of black shale formation

assessing the record and causes of late triassic extinctions accelerated biotic turnover during the late triassic has led to the perception of an end triassic mass extinction event now regarded as one of the big five extinctions close examination of the fossil record reveals that many groups thought to be affected severely by this event such as ammonoids bivalves and conodonts instead were in decline throughout the late triassic and that other groups were relatively unaffected or subject to only regional effects explanations for the biotic turnover have included both gradualistic and catastrophic mechanisms regression during the rhaetian with consequent habitat loss is compatible with the disappearance of some marine faunal groups but may be regional not global in scale and cannot explain apparent synchronous decline in the terrestrial realm gradual widespread aridification of the pangaean supercontinent could explain a decline in terrestrial diversity during the late triassic although evidence for an impact precisely at the boundary is lacking the presence of impact structures with late triassic ages suggests the possibility of bolide impact induced environmental degradation prior to the end triassic widespread eruptions of flood basalts of the central atlantic magmatic province camp were synchronous with or slightly postdate the system boundary emissions of co2 and so2 during these eruptions were substantial but the contradictory evidence for the environmental effects of outgassing of these lavas remains to be resolved a substantial excursion in the marine carbon isotope record of both carbonate and organic matter suggests a significant disturbance of the global carbon cycle at the system boundary release of methane hydrates from seafloor sediments is a possible cause for this isotope excursion although the triggering mechanism and climatic effects of such a release remain uncertain d 2003 elsevier b v all rights reserved

volcanism and deep ocean acidification across the end triassic extinction event abstract the end triassic extinction event marks one of the big five mass extinction events of the phanerozoic the ultimate cause of the extinction is considered to be volcanic activity at the central atlantic magmatic province camp yet the underlying nature of global environmental changes that accompanied the biotic turnover remains elusive here we present chemical and mineralogical studies across the end triassic extinction level of the deep sea chert sequence inuyama japan depleted hematite content normalized by terrigenous material predated the end triassic extinction level with significant rock color change from brick red to purple which is consistent with the rock magnetic records of hematite reported this suggests the loss of authigenic hematite possibly due to the acidification of bottom water and the underlying sediment pore water this timing is consistent with the initial eruption of camp volcanism suggesting a catastrophic release of greenhouse gases as a cause of deep ocean acidification across the end triassic extinction interval mgo al2o3 fe2o3 al2o3 and al2o3 sio2 increased with change in color from purple to dusty red this trend became close to those of weathered camp basalts in arid area implying that it became the considerable source of aeolian dust in cherts after the end triassic extinction event these temporal relations support the synchrony among the initial eruption of camp deep ocean acidification and the end triassic extinction similar rock color changes of cherts might have potential information for the volcanisms and deep ocean acidification in other geologic events

biogeochemical constraints on the triassic jurassic boundary carbon cycle event 1 the end triassic mass extinctions represent one of the five most severe biotic crises in earth history yet remain one of the most enigmatic ongoing debate concerns the environmental effects of the central atlantic magmatic province camp eruptions and their linkage with the mass extinction event across the triassic jurassic boundary there is conflicting paleo evidence for changes in atmospheric pco2 during the extrusion of the camp basalts studies on sediments from european and pacific localities have however identified a substantial negative isotopic anomaly up to 3 5 across the tr j boundary providing an important indicator of changes in the operation of the ancient global carbon cycle we sought to explain the paleo evidence by utilizing a carbon cycle model for the hothouse world of the end triassic that emphasizes the chemical weathering of silicate and carbonate rocks and the ocean carbonate chemistry we find that volcanic co2 outgassing fails to fully account for either a sufficient rise in atmospheric pco2 indicated by the stomata of fossil leaves or the sedimentary isotopic fingerprint instead the scenario that best fits all of the geologic evidence is a positive feedback loop in which warming due to a buildup of volcanically derived co2 triggers destabilization of seafloor methane hydrates and the catastrophic release of ch4 palfy et al 2001 we calculate that this carbon cycle perturbation was huge involving the release of 8000 9000 gt c as co2 during the camp basaltic eruptions and 5000 gt c as ch4 in the model the initial isotopic excursion is assumed to take place over 70 kyr while complete reequilibration of the ocean atmosphere system with respect to co2 is accomplished over 700 1000 kyr our results thus provide a preliminary theoretical explanation for the bioevents estimated pco2 changes and isotopic excursions observed in marine and continental sediments at this time

a new correlation of triassic jurassic boundary successions in nw europe nevada and peru and the central atlantic magmatic province a time line for the end triassic mass extinction abstract understanding the end triassic mass extinction event 201 36 ma requires a clear insight into the stratigraphy of boundary sections which allows for long distance correlations and correct distinction of the sequence of events however even after the ratification of a global stratotype section and point global correlations of tjb successions are hampered by the fact that many of the traditionally used fossil groups were severely affected by the crisis here a new correlation of key tjb successions in europe u s a and peru based on a combination of biotic palynology and ammonites geochemical 13 c org and radiometric u pb ages constraints is presented this new correlation has an impact on the causality and temporal development during the end triassic event it challenges the hitherto used standard correlation which has formed the basis for a hypothesis that the extinction was caused by more or less instantaneous release of large quantities of light carbon methane to the atmosphere with catastrophic global warming as a consequence the new correlation instead advocates a more prolonged scenario with a series of feedback mechanisms as it indicates that the bulk of the hitherto dated high titanium quartz normalized volcanism of the central atlantic magmatic province camp preceded or was contemporaneous to the onset of the mass extinction in addition the maximum phase of the mass extinction which affected both the terrestrial and marine ecosystems was associated with a major regression and repeated enhanced earthquake activity in europe a subsequent transgression resulted in the formation of hiati or condensed successions in many areas in europe later phases of volcanic activity of the camp producing low titanium quartz normalized and high iron quartz normalized basaltic rocks continued close to the first occurrence of jurassic ammonites and the defined tjb during this time the terrestrial ecosystem had begun to recover but the marine ecosystem remained disturbed

late triassic to early jurassic palaeogeography and eustatic history in the nw tethyan realm new insights from sedimentary and organic facies of the csővar basin hungary abstract sedimentary and organic facies of a continuous late triassic early jurassic toe of slope to basin succession of the ne transdanubian range n hungary was studied in order to reconstruct the palaeogeographical and eustatic evolution of the cs var basin an intraplatform basin of the nw neotethys margin characteristic facies successions point to sea level changes of different hierarchies cyclic patterns inferred to result from orbital eccentricity forcing are also reflected in the stratigraphical distribution of sedimentary organic matter furthermore both palaeontological and isotope data document drastic climatic changes around the triassic jurassic boundary detecting sea level changes leads to a more accurate interpretation of the late triassic palaeogeographic setting and evolution of the transdanubian range s carbonate platform our integrated sedimentological and palynological data suggest a complex topography and dynamic sea level history which contradicts a previous model of broad uniform platform setting and lack of any major drowning and emersion events during the late triassic

palaeoenvironmental significance of carbon and oxygen isotope stratigraphy of marine triassic jurassic boundary sections in sw britain abstract carbon isotope stratigraphy is a useful tool for stratigraphic correlation especially for strata deposited during major perturbations of the carbon cycle that affected the marine terrestrial and atmospheric reservoirs for the triassic jurassic boundary effectively defined by a first order mass extinction major fluctuations in carbon isotope values have been well documented but these datasets have generally been derived from bulk rock samples hence the extent to which features of the isotopic curve reflect diagenetic alteration or changing proportions of constituent materials is unconstrained here carbon and oxygen isotope data are presented from well preserved oyster shells liostrea comprising low magnesium calcite a mineral species relatively resistant to diagenetic alteration samples were obtained from lavernock point glamorgan wales a coastal section close to a candidate stratotype for the base of the jurassic at st audrie9s bay somerset england the carbon isotope signature from st audrie9s bay previously defined on the basis of analysis of bulk organic matter is confirmed by our new data major features are 1 the upper part of an initial9 negative isotope excursion in the lowest part of the section followed by 2 a pronounced positive excursion and 3 an extended main9 negative isotope excursion in the highest part of the section the data confirm that the carbon isotope stratigraphy previously documented from bulk organic matter in sw england records the chemical composition of the contemporaneous seawater bulk carbonates sampled over the same interval near lyme regis england show similar trends to those from oyster calcite in the lower part of the study section but there are more 13 c depleted values up section these lower values probably result from an admixture of primary and diagenetic carbonate palaeotemperatures calculated from oxygen isotope values from lavernock point oyster shells are relatively cool at the beginning of the positive carbon isotope excursion and increased by up to 10 c during the main negative carbon isotope excursion the new results are compatible with the view that positive carbon isotope excursions correspond to times of low atmospheric carbon dioxide content whereas negative carbon isotope excursions correspond to times of high atmospheric carbon dioxide content as is also found to be the case during the early jurassic toarcian oceanic anoxic event the mg ca and sr ca ratios and 18 o of investigated liostrea hisingeri show no correlation supporting data from modern bivalves that indicate that incorporation of mg and sr is controlled mainly by factors other than temperature

discussion on palaeoecology of the late triassic extinction event in the sw ukjournal vol 165 2008 pp 319 332 jonathan radley writes the penarth group of late triassic and possibly ranging to early jurassic age of the southern uk marks a marine transgression and the establishment of a shallow epicontinental seaway hallam el shaarawy 1982 warrington ivimey cook 1992 influenced by regressive transgressive pulses and characterized by rapid facies changes hallam wignall 2004 hesselbo et al 2004 a well documented invertebrate macrofauna includes corals brachiopods molluscs and echinoderms swift martill 1999 facies developments range from storm influenced shallow marine mudrocks westbury formation upwards into calcareous mudstones siltstones and essentially fine grained carbonates lilstock formation demonstrating extremely shallow water conditions wave ripples storm beds desiccation and omission surfaces swift 1999 a wignall 2001 hallam wignall 2004 the low diversity macrofauna of the lilstock formation has frequently been attributed to salinities deviating from that of normal seawater within shallow water partly landlocked settings isolated from the open sea hallam el shaarawy 1982 swift 1995 allison wright 2005 however widespread occurrences of stenohaline marine macrofossils such as corals and echinoderms swift martill 1999 suggest that salinity fluctuations were at most slight wignall 2001 mander et al 2008 have presented high resolution benthic macrofaunal data principally from molluscan macrofossils for significant palaeoecological change within the penarth group of two key sections in the sw uk their detailed results demonstrate loss of taxonomic richness within the uppermost westbury formation lower lilstock formation cotham member interval latest rhaetian followed by a poorly fossiliferous interval represented by the latest rhaetian or early hettangian upper lilstock formation upper cotham member lower langport member they attributed this pattern to an extinction event followed by a post extinction dead zone the latter coinciding with the onset of a negative organic carbon isotope excursion and an extinction event recorded in the terrestrial palynoflora the relatively diverse shelly

an organic record of terrestrial ecosystem collapse and recovery at the triassic jurassic boundary in east greenland abstract terrestrial ecosystem collapse at the end of the triassic period coincided with a major mass extinction in the marine realm and has been linked to increasing atmospheric carbon dioxide global warming and fire activity extractable hydrocarbons in samples from the fluvial triassic jurassic boundary section at astartekloft east greenland were analyzed to investigate the molecular and isotopic organic record of biotic and environmental change during this event carbon isotopic compositions of individual plant wax lipids show a 4 negative excursion coinciding with peak extinction and a further decrease of 2 coinciding with peak p co 2 as estimated from the stomatal indices of fossil gingkoales an increase of 30 in the hydrogen isotopic compositions of the same plant wax lipids coincides with ecosystem collapse suggesting that the biotic crisis was accompanied by strong hydrologic change concentrations of polycyclic aromatic hydrocarbons related to combustion also increase together with abrupt plant diversity loss and peak with fossil charcoal abundance and maximum plant turnover supporting the role of fire in terrestrial extinctions anomalously high concentrations of a monoaromatic diterpenoid related to gymnosperm resin derivatives and similar to dehydroabietane occur uniquely in samples from the boundary bed indicating that environmental stress factors leading to peak plant extinction stimulated increased resin production and that plant resin derivatives may be effective biomarkers of terrestrial ecosystem stress

nitrogen isotope record of a perturbed paleoecosystem in the aftermath of the end triassic crisis doniford section sw england 1 the triassic jurassic transition tj is characterized by successive perturbations of the carbon cycle during a time of biotic disruption as recorded by the carbon isotopic composition of organic matter 13corg the nitrogen isotopic composition of sedimentary organic matter 15norg constitutes a key parameter to explore the functioning of the ecosystem during carbon cycle perturbations and biological crises because it provide information on seawater redox conditions and or nutrient cycling here we report the first continuous 15norg record across the tj transition at the doniford bay section bristol channel basin uk combined with 13corg kerogen typology and carbon 13cmin and oxygen 18omin isotopic composition of bulk carbonates the end triassic is characterized by a major negative excursion both in 13corg and 13cmin very low toc total organic carbon wt and high 15norg values associated with a sea level lowstand a second 13corg negative excursion occurs during the lower hettangian this interval is characterized by phases of carbonate production increase alternated with phases of exceptional accumulations of type i organic matter up to 12 associated with lower 15norg and 13corg this alternation likely reflects a succession of nutrient input increase to the basin leading to enhanced productivity and eutrophication which promoted a primary production driven by organic walled prokaryotic organisms the following om export increase generates anaerobic conditions within the basin these events occur between periods of relatively good seawater column ventilation and nutrient recycling boosting the carbonate producer recovery ecosystems remain perturbed in the bristol channel basin during the aftermath of the end triassic crisis

marine osmium isotope record across the triassic jurassic boundary from a pacific pelagic site the triassic jurassic t j boundary ca 200 ma represents one of the major mass extinction events of the phanerozoic however the cause of this event remains controversial because of a paucity of geological evidence in this study we present an isotopic record of osmium extracted from a bedded chert succession across the t j boundary in the kurusu section of japan deposited within a paleo pacific panthalassa deep basin the data show a gradual decrease in seawater 187 os 188 os values during the rhaetian followed by a sharp increase in the latest rhaetian and a subsequent stable phase across the t j boundary the decreasing trend of 187 os 188 os values during the rhaetian indicates a gradual increase in the relative supply rate of unradiogenic os from the mantle associated with emplacement of the central atlantic magmatic province the subsequent shift toward radiogenic values reflects an increased supply of radiogenic os due to enhanced continental weathering this interval marks more negative isotopic values of organic carbon the onset of radiolarian faunal turnover and conodont extinctions indicating that the rapid increase in continental weathering rate was closely linked to the perturbation of the carbon cycle and the t j biotic crisis

holocene coastal dune development and environmental changes in apulia southern italy abstract the coastal area of southern apulia is characterised by marine deposits of pleistocene and holocene ages it shows the effects of different phases of coastal morphology evolution during the middle and upper pleistocene a number of marine terraces were shaped in some places they are characterised by thin beach deposits along with a dune belt and relative back dune deposits two important morphogenetic phases occurred during the holocene the former was characterised by deposition of beach deposits placed slightly above present mean sea level and by formation of dune belts which were radiometrically aged about 6000 years bp this event marks the end of the rapid postglacial transgression that occurred during the holocene climatic optimum during the younger phase dated at about 2500 years bp deposition of aeolian sands occurred archaeological and morphological evidences suggest that this phase should be related to a low sea level stand followed by a slow sea level rise up to the present position and by humid temperate climatic conditions the collected data about the holocene dune belts occurring along the apulian coastline suggest that main phases of dune development could be related to the effects of sea level changes climatic conditions and in a subordinate way to human activity

the nonmarine triassic jurassic boundary in the newark supergroup of eastern north america abstract for the last three decades the position of the triassic jurassic boundary tjb in nonmarine strata has largely been based on its palynostratigraphic placement just below the oldest basalts of the central atlantic magmatic province camp in the newark supergroup of eastern north america this boundary however is demonstrably older than the tjb as it is defined in marine strata thus the palynostratigraphic change used to place this tjb in the newark most resembles a late norian change in the european section and does not correspond to any palynological event at the marine defined tjb conchostracan biostratigraphy suggests that the tjb is in the newark extrusive zone above the oldest camp basalt and vertebrate biostratigraphy is consistent with this placement of the tjb radioisotopic ages indicate that the tjb defined in marine strata is no older than 200 ma but the oldest camp basalts of the newark supergroup consistently yield ages averaging about 201 ma magnetostratigraphic correlation of the newark section to the tjb section at st audrie s bay in england also indicates that the onset of camp volcanism in the newark supergroup is older than the marine tjb correlations based on carbon and osmium isotopes are also consistent with this correlation thus all data indicate that the tjb in the newark supergroup is above the lowest camp basalt in the newark extrusive zone correct placement of the tjb in the newark supergroup allows key nonmarine and marine events to be sequenced across the tjb indicating the following succession of events crurotarsan thecodont extinction the palynofloral turnover in the newark the first camp eruptions the extinctions of rhaetian ammonites and conodonts and the first appearance of jurassic psiloceratid ammonites

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

redox conditions and nitrogen cycling during the triassic jurassic transition a new perspective from the mid panthalassa abstract we determined redox sensitive element concentrations along with 15ntn values from the triassic jurassic shales interbedded within deep sea cherts at the katsuyama section sw japan to clarify the redox and related nitrogen cycle conditions in mid panthalassa during the tjb biotic crisis focusing particularly on the linkages with camp volcanism slight enrichments of mn and mo across the tjb suggest a vertically expanded mid panthalassic omz above a well oxygenated deep ocean moreover high resolution 15ntn records during the triassic jurassic transition exhibit a negative nitrogen isotope excursion nnie just above the tjb relative to the previously reported negative carbon isotope excursion ncie across the tjb the nnie can be divided into two intervals negative interval 1 ni 1 during the ncie and ni 2 after the ncie the nnie can be explained as an interval of nitrate rich conditions reflecting an oxic panthalassic ocean during the triassic jurassic transition our geochemical dataset provides new insights into environmental perturbations in mid panthalassia during the tjb biotic crisis 1 a vertically expanded omz and decreased primary productivity owing to global warming caused by camp volcanism across the tjb resulted in an increased nitrate concentration during the ni 1 and 2 eutrophic nitrate rich conditions developed in mid panthalassa during the ni 2 due to the enhanced continental weathering and deep water upwelling significantly our results are the first to demonstrate that the omzs were expanded not only in the shallow marine regions but also in pelagic sites across the tjb suggesting that the globally expanded omzs can be regarded as a crucial driver for the tjb biotic crisis

global perturbations of carbon cycle during the triassic jurassic transition recorded in the mid panthalassa abstract to examine environmental changes in the biosphere during the triassic jurassic transition with a particular focus on the global carbon cycle related to central atlantic magmatic provinces camp volcanism in the mid panthalassa we established stratigraphic 13 c org variations using rhaetian late triassic to hettangian early jurassic shales interbedded within deep sea cherts in the katsuyama section in the mino tanba belt sw japan high resolution record of rhaetian to hettangian 13 c org values in the mid panthalassa contain three distinct negative carbon isotopic excursions ncies before and across the triassic jurassic boundary tjb the rhaetian ncie1 and ncie2 show a deviation of 5 0 from ca 24 0 to ca 29 0 whereas ncie3 across the tjb shows a 3 5 deviation from ca 23 5 to ca 27 0 our newly obtained ncies in the deep mid panthalassa can be correlated with the 13 c org records in the shallow marine tethyan regions i e precursor initial and main cies suggesting that three ncies in the tethys and mid panthalassa likely reflected the global perturbations of the carbon cycle three ncies before and across the tjb can be interpreted as the consequence of the multiple camp volcanic episodes i e the release of thermogenic methane from organic rich sediments by camp intrusive rocks for ncie1 and large scale volcanically derived carbon species for ncie2 and ncie3 in addition progressive increase of atmospheric p co 2 throughout three ncies was possibly attributed to accumulation of volcanically derived co 2 from multiple camp eruptions which resulted in the development of ocean acidification across the tjb on the other hand in view of the oxic conditions in the deep mid panthalassa during three ncies the development of coeval oceanic anoxic euxinic conditions was restricted solely to shallow marine regions therefore ocean acidification together with localized shallow marine anoxia acted as environmental stresses on the biosphere which eventually resulted in the severe biotic crisis at the end of the triassic

major perturbation in sulfur cycling at the triassic jurassic boundary stable sulfur isotopes from the reduced sulfur fraction of late triassic early jurassic marine sediments at kennecott point in british columbia canada show evidence for a major perturbation in sulfur cycling coincident with a major carbon cycle perturbation in the wake of a mass extinction event at the triassic jurassic boundary the 34 s of reduced sulfur shifts from values consistent with open system bacterial sulfate reduction 30 to values higher than any previously reported for early jurassic sulfates 20 and consistent with complete utilization of sulfate and rayleigh fractionation in a closed system we suggest that this isotopic shift was initiated by declining seawater sulfate concentration due to evaporite deposition in nascent atlantic rift zones and enhanced by a local mechanism such as a decoupling of the zone of sulfate reduction from the sulfate supply due to a catastrophic increase in the flux of land derived sediments reaching the sea in the wake of massive terrestrial plant die off during the triassic jurassic mass extinction

biostratigraphy of the late middle pleistocene middle neopleistocene of the southern urals region abstract a summary of published and unpublished materials on the stratigraphy of the late middle pleistocene middle neopleistocene according to the russian stratigraphic scheme of the southern urals region is given deposits of different origin in the regional stratigraphic units are characterized the results of mammalian investigations provide the basis for the stratigraphical subdivision mollusca and palynology are used for the reconstruction of the palaeoenvironments the stratigraphical positions of the main middle neopleistocene localities and precise definitions of the stratigraphical scheme of the southern urals region are discussed the southern urals subdivisions are correlated with the western european stratigraphical schemes holsteinian saalian interval

testing the limits in a greenhouse ocean did low nitrogen availability limit marine productivity during the end triassic mass extinction abstract the end triassic mass extinction has been characterized as a greenhouse extinction related to rapid atmospheric warming and associated changes in ocean circulation and oxygenation the response of the marine nitrogen cycle to these oceanographic changes and the extent to which mass extinction intervals represent a deviation in nitrogen cycling from other ice free greenhouse periods of earth history remain poorly understood the well studied kennecott point section in haida gwaii british columbia canada was deposited in the open panthalassic ocean and is used here as a test case to better understand changes in the nitrogen cycle and marine productivity from the pre crisis greenhouse of the rhaetian to the latest rhaetian crisis interval we estimated marine productivity from the late norian to the early hettangian using toc and p based paleoproductivity transform equations and then compared these estimates to records of sedimentary nitrogen isotopes redox sensitive trace elements and biomarker data major negative excursions in 15 n to 0 correspond to periods of depressed marine productivity during these episodes the development of a stable pycnocline below the base of the photic zone suppressed vertical mixing and limited n availability in surface waters leading to low productivity and increased nitrogen fixation as well as ecological stresses in the photic zone the subsequent shoaling of euxinic waters into the ocean surface layer was fatal for most triassic marine fauna although the introduction of regenerated nh 4 into the photic zone may have allowed phytoplankton productivity to recover these results indicate that the open ocean nitrogen cycle was influenced by climatic changes during the latest triassic despite having existed in a greenhouse state for over 50 million years previously and that low n availability limited marine productivity for hundreds of thousands of years during the end triassic crisis

disentangling the hettangian carbon isotope record implications for the aftermath of the end triassic mass extinction 1 this study provides an organic carbon stable isotope 13corg record calibrated with detailed ammonite biostratigraphy following the end triassic biological crisis precise correlation between this crucial fossil group and the 13corg record is key to understanding feedbacks between biological and environmental events following mass extinction the latest triassic and hettangian 13corg record shows several negative and positive excursions the end triassic negative shift coinciding with the mass extinction interval is followed by a positive excursion in the earliest hettangian psiloceras spelae beds which marks the onset of recovery in the marine ecosystem this positive trend is interrupted by a second negative 13corg excursion in the p pacificum beds related to a minor ammonite extinction event this pattern of the 13corg curve culminates in the uppermost hettangian angulata zone major positive excursion this indicates that both the ecosystem and the carbon cycle remained in a state of perturbation for at least 2 ma although the recovery of some pelagic taxa already began at the base of jurassic the early and late hettangian positive 13corg excursions have been confused in several recent papers here we show that during the hettangian there are indeed two distinct positive 13corg excursions phases of anoxia and further pulses of central atlantic magmatic province volcanism during the hettangian might have inhibited the full recovery for that interval of time the main liasicus angulata organic positive cie carbon isotope excursion during the late hettangian might be related to gradual decreasing of pco2 due to protracted high organic burial and coincides with a second phase of recovery as indicated by a pulse of ammonoid diversification

the asynchronous disappearance of conodonts new constraints from triassic jurassic boundary sections in the tethys and panthalassa abstract the end triassic extinction event ete has been recognized in numerous sections worldwide and it is usually marked by three negative carbon isotope excursions ncies named precursor p ncie initial i ncie and main m ncie negative carbon isotope excursions these three ncies are significant characteristics of this time interval and they are likely related to the emplacement of the central atlantic magmatic province camp that is considered the main trigger of the ete stable carbon isotope excursions commonly related to biotic turnovers and extinctions play an important role in stratigraphic correlations particularly around the triassic jurassic boundary tjb this time interval records the disappearance of conodonts elements of a feeding apparatus belonging to marine organisms that populated the paleozoic early mesozoic seas and which became extinct across the tjb so far the interpretation of conodont extinction has remained ambiguous as the timing of its last occurrence was debated which in turn hindered our understanding of the main cause s that could have led to their disappearance here we present and compare integrated data of nine tjb sections from different areas tethys and panthalassa and different depositional environments i e shallow vs deep water or proximal vs distal shelf each of these sections record both the last occurrences of latest triassic conodont taxa and pronounced changes in the carbon isotopic composition of organic matter across the tjb interval our analysis of chemo and integrated biostratigraphic correlation suggests that the final extinction of the taxon conodonta was asynchronous

triassic jurassic organic carbon isotope stratigraphy of key sections in the western tethys realm austria the late triassic period is recognized as one of the five major mass extinctions in the fossil record all these important intervals in earth history are associated with excursions in c isotope records thought to have been caused by perturbations in the global carbon cycle the nature and causes of c isotopic events across the triassic jurassic t j transition however are poorly understood we present several new high resolution organic c isotope records from the eiberg basin austria including the proposed global boundary stratotype section and point gssp for the base of the jurassic the triassic jurassic boundary interval in these records is characterized by the initial and main negative organic carbon isotope excursions cie of up to 8 the initial and main cies are biostratigraphically constrained by first and last occurrences of boundary defining macro and microfossils e g ammonites high resolution c isotope records appear to be an excellent correlation proxy for this period in the eiberg basin pyrolysis analysis demonstrates increased hydrogen index hi values for organic matter coinciding with the initial cie terrestrial organic matter influx and mass occurrences of green algae remains may have influenced the c isotope composition of the sedimentary organic matter this may have contributed to the extreme amplitude of the initial cie in the eiberg basin

the quest for chron e23r at partridge island bay of fundy canada camp emplacement postdates the end triassic extinction event at the north american craton the partridge island stratigraphic section at the bay of fundy maritime canada reveals a continental sedimen tary succession with the end triassic mass extinction level closely followed by basalts of the central atlantic magmatic province camp new paleomagnetic data show that a short reverse magnetic polarity chron correlative to e23r of the newark geomagnetic polarity time scale gpts is present below the extinction event organic carbon isotope data and basalt geochemistry further indicate that the onset of camp emplacement in the bay of fundy was roughly synchronous with emplacement in the newark basin but slightly postdates the oldest camp volcanism in morocco by 20 ka these re sults confirm the potential for long distance camp correlations based on geochemical trace elements indicate substantiate provincialism of latest triassic palynoflora and suggest a very concise period 100 ka of camp emplacement in the northern atlantic region resume la section stratigraphique de l ile partridge dans la baie de fundy maritimes canada revele une succession se dimentaire continentale dans laquelle le niveau d extinction massive de la fin du trias est suivi de pres par des basaltes de la province magmatique centre atlantique camp de nouvelles donnees paleomagnetiques montrent qu un chrone de breve inversion de polarite magnetique correle a e23r de l echelle de temps geomagnetique de polarite de newark est present sous l evenement d extinction des donnees d isotopes du carbone organique et la geochimie des basaltes indiquent de plus que le debut de la mise en place de la camp dans la baie de fundy a ete passablement contemporain avec la mise en place du bassin newark mais cette mise en place a eu lieu peu de temps apres le plus ancien volcanisme camp au maroc soit environ 20 ka ces resultats confirment le potentiel de correler la camp sur de longues distances en se basant sur des ele ments traces geochimiques ils indiquent et valident le provincialisme de la plus recente palynoflore du trias et suggerent une tres courte periode 100 ka pour la mise en place de la camp dans la region de l atlantique nord traduit par la redaction

isotopic evidence bearing on late triassic extinction events queen charlotte islands british columbia and implications for the duration and cause of the triassic jurassic mass extinction stable isotope analyses of late triassic to earliest jurassic strata from kennecott point in the queen charlotte islands british columbia canada shows the presence of two distinct and different organic carbon isotope anomalies at the norian rhaetian and rhaetian hettangian triassic jurassic stage boundaries at the older of these boundaries which is marked by the disappearance of the bivalve monotis the isotope record shows a series of short lived positive excursions toward heavier values strata approaching this boundary show evidence of increasing anoxia at the higher boundary marked by the disappearance of the last remaining triassic ammonites and over 50 species of radiolarians the isotopic pattern consists of a series of short duration negative anomalies the two events separated by the duration of the rhaetian age comprise the endtriassic mass extinction while there is no definitive evidence as to cause the isotopic record does not appear similar to that of the impact caused cretaceous tertiary boundary extinction d 2004 published by elsevier b v

major environmental change and bonebed genesis prior to the triassic jurassic mass extinction we present new geochemical and sedimentological data from marginal marine strata of penarth bay south wales uk to elucidate the origin of widespread but enigmatic concentrations of vertebrate hard parts bonebeds in marine successions of rhaetian age late triassic sedimentological evidence shows that the phosphatic constituents of the bonebeds were subjected to intense phosphatization in shallow current dominated settings and subsequently reworked and transported basinward by storms interbedded organic rich strata deposited under quiescent and poorly oxygenated conditions record enhanced phosphorus regeneration from sedimentary organic matter into the water column and probably provided the main source of phosphate required for heavy bonebed clast phosphatization the stratigraphically limited interval showing evidence for oxygen depletion and accelerated p cycling coincides with a negative 4 organic carbon isotope excursion which possibly reflects supra regional changes in carbon cycling and clearly predates the initial isotope excursion characterizing many triassic jurassic boundary strata our data indicate that rhaetian bonebeds are the lithological signature of profound climatically driven changes in carbon cycling and redox conditions and support the idea of a multi pulsed environmental crisis at the end of the triassic possibly linked to successive episodes of igneous activity in the central atlantic magmatic province supplementary material sample positions data table and a detailed stratigraphic log from the upper triassic of penarth bay south wales uk are available at http www geolsoc org uk sup18510

vegetation dynamics and climate during the deglaciation in the south adriatic basin from a marine record the pollen record of a marine core in the south adriatic basin that is radiometrically dated and correlated to the global climate variation by the oxygen isotope curve documents the vegetation changes which occurred around that basin since 17 ka thousands year bp during the end of the last glacial maximum at 16 7 15 ka the altitudinal range is occupied at low and high elevations by a desert and a semi desert dominated by the shrubby sage brush artemisia and at middle elevation by a grass steppe with stands of pine trees where soil conditions are favourable during the deglaciation between 15 and 10 ka a steppe forest with a succession of deciduous trees appears at middle elevation within the grass steppe but its development is interrupted by a set back a re expansion of the semi desert which is coeval with the younger dryas of higher european latitude the holocene is identified by the spread of the mixed deciduous and mediterranean forests which culminates between 8 6 and 6 ka during the end of the boreal and the atlantic chronozones while the most recent sapropel is formed in the deep marine basins of the eastern mediterranean including the south adriatic one between the cold and arid glacial maximum and the warmest and wettest climate optimum during the atlantic chronozone this vegetation dynamics is constrained by the availability of moisture at low elevation by temperature at high elevation and by a combination of both at middle elevation

a biocalcification crisis at the triassic jurassic boundary recorded in the budva basin dinarides montenegro volcanic activity in the central atlantic magmatic province resulting in an increased flux of co 2 so 2 and ch 4 into the oceans and atmosphere has been proposed as one of the mechanisms causing the biotic crisis at the triassic jurassic boundary oceanic uptake of co 2 due to extreme greenhouse conditions should have had an impact on ocean chemistry and the position of the calcite compensation depth in this study we chose two pelagic sections from the budva basin as archives for paleoceanographic change across the triassic jurassic boundary in deep water settings our record represents the first documentation of a sudden termination of carbonate deposition across the triassic jurassic boundary in a pelagic deep water environment based on radiolarian biostratigraphy the system boundary is placed at the sharp lithological contact between two pelagic formations the upper triassic limestones and lower jurassic siliceous limestones alternating with shales a rapid drop of carbonate content from 90 to less than 10 occurred contemporaneous with a negative anomaly in the stable carbon isotope record measured in both bulk carbonate 1 3 and bulk organic matter 1 1 the abrupt reduction of carbonate content in the budva basin was the result of either increased carbonate dissolution causing shoaling of the calcite compensation depth or reduced carbonate input due to biocalcification crisis both nonexclusive scenarios support the hypothesis of decreased ocean saturation with respect to calcium carbonate which could be a direct consequence of increased co 2 so 2 and ch 4 fluxes

human induced hydrogeological changes and sinkholes in the coastal gypsum karst of lesina marina area foggia province italy abstract in 1930 a canal was excavated to connect the lesina lagoon with the adriatic sea modifying the track of the previous existing acquarotta canal the 1100 m long stretch of the canal situated next to the coast exposed unknown highly cavernous gypsum bedrock underlying a loose sandy cover during the last two decades a large number of cover collapse and cover suffosion sinkholes have formed along two bands situated next to the canal impinging the adjacent lesina marina residential area the area affected by subsidence has increased exponentially from 1999 to 2009 the tight spatial correlation between the sinkholes and the canal reveals that the subsidence phenomenon has been induced by the local hydrogeological changes caused by the canal in the coastal evaporite aquifer 1 local lowering of the average water table 2 deflection of the groundwater flow lines towards the canal and increase in flow velocity 3 amplification of the groundwater level oscillations largely controlled by the tidal regime 4 local reversals in the groundwater flow changing the canal temporarily from effluent to influent these changes in the hydrogeological functioning of the system have favoured both internal erosion and karstification processes hydrochemical evidence reveals that gypsum dissolution is a currently active process favoured by fresh water and sea water mixing and cation exchange processes most likely the partial replacement of a concrete lining in the canal by pervious gabions in 1993 provided more adequate conditions for the evacuation of the sediments filling the karst conduits accelerating internal erosion and sinkhole development

carbon isotope anomaly and other geochemical changes at the triassic jurassic boundary from a marine section in hungary most mass extinctions are linked with carbon isotope excursions implying that biotic crises are coupled with changes in the global carbon cycle the isotopic evolution during the end triassic extinction is far less documented than that for the other major phanerozoic extinctions here we report a sharp and short lived 23 5 excursion in carbon isotope values for carbonate d 13 ccarb corresponding to a 22 excursion in the isotopic composition of marine organic matter d 13 corg and other geochemical

environmental controls on marine ecosystem recovery following mass extinctions with an example from the early triassic abstract the recovery of marine ecosystems following a mass extinction event involves an extended interval of increasing biotic diversity and ecosystem complexity the pace of recovery may be controlled by intrinsic ecosystem or extrinsic environmental factors here we present an analysis of changes in marine conditions following the end permian mass extinction with the objective of evaluating the role of environmental factors in the protracted 5 myr long recovery of marine ecosystems during the early triassic specifically our study examines changes in weathering productivity and redox proxies in three sections in south china chaohu daxiakou and zuodeng and one in northern india mud our results reveal 1 recurrent environmental perturbations during the early triassic 2 a general pattern of high terrestrial weathering rates and more intensely reducing marine redox conditions during the early griesbachian late griesbachian mid smithian and more weakly the mid spathian 3 increases in marine productivity during the aforementioned intervals except for the early griesbachian and 4 stronger and more temporally discrete intervals of environmental change in deepwater sections chaohu and daxiakou relative to shallow and intermediate sections zuodeng and mud our analysis reveals a close relationship between episodes of marine environmental deterioration and a slowing or reversal of ecosystem recovery based on metrics of biodiversity within community alpha diversity infaunal burrowing and ecosystem tiering we infer that the pattern and pace of marine ecosystem recovery was strongly modulated by recurrent environmental perturbations during the early triassic these perturbations were associated with elevated weathering and productivity fluxes implying that nutrient and energy flows were key influences on recovery more regular secular variation in deepwater relative to shallow water environmental conditions implies that perturbations originated at depth i e within the oceanic thermocline and influenced the ocean surface layer irregularly finally we compared patterns of environmental disturbance and ecosystem recovery following the other four big five phanerozoic mass extinctions to evaluate whether commonalities exist in general the pace of ecosystem recovery depends on the degree of stability of the post crisis marine environment

abrupt and gradual extinction among late permian land vertebrates in the karoo basin south africa the karoo basin of south africa exposes a succession of upper permian to lower triassic terrestrial strata containing abundant terrestrial vertebrate fossils paleomagnetic magnetostratigraphic and carbon isotope data allow sections to be correlated across the basin with this stratigraphy the vertebrate fossil data show a gradual extinction in the upper permian punctuated by an enhanced extinction pulse at the permian triassic boundary interval particularly among the dicynodont therapsids coinciding with negative carbon isotope anomalies

multiple phases of carbon cycle disturbance from large igneous province formation at the triassic jurassic transition the end triassic mass extinction ca 201 4 ma coincided with a major carbon cycle perturbation based on an 5 6 negative excursion in 13 c toc total organic carbon records both events coincided directly with the onset of massive flood basalt volcanism in the central atlantic magmatic province camp organic carbon isotope data from the western tethys ocean austria and the germanic basin uk and germany however demonstrate earlier disruption of the global carbon cycle preceding camp eruptions a 2 3 late rhaetian precursor negative excursion in marine and continental 13 c toc records is matched by a negative perturbation in 13 c leaf data suggesting multiple events of rhaetian atmospheric 13 c depletion intruding dike and sill systems preceding camp eruptive volcanic activity may have released 3000 7000 gt of isotopically light carbon as thermogenic methane from subsurface organic rich strata this possibly caused an end triassic atmospheric p co 2 increase and reduced ecosystem stability before the actual onset of eruptive volcanic activity in the camp region we present a model that identifies three phases of disturbances in global biogeochemical cycles related to the formation of this large igneous province

an extended organic carbon isotope record across the triassic jurassic boundary in the queen charlotte islands british columbia canada abstract new lithologic and organic carbon isotope data are presented for the triassic jurassic boundary section at kennecott point queen charlotte islands british columbia canada the previously reported late norian to earliest hettangian record is extended by over 130 m and three new isotopic features are revealed the record now shows a negative offset in baseline carbon isotope values from approximately 29 in the late norian to 31 in the hettangian this offset is accompanied by the previously reported 2 negative excursion at the triassic jurassic boundary and a 5 positive excursion in the early hettangian there is a significant long term negative isotopic trend in the hettangian interval of the section which may be due to camp volcanism the positive excursion is attributed to a decline in bio calcification as well as changes in microbial ecology both related to the mass extinction at the triassic jurassic boundary

the pliensbachian toarcian early jurassic extinction a global multi phased event abstract during the pliensbachian toarcian interval of the early jurassic there is a well known second order marine extinction that is observable at the species and genus levels ammonite diversity data from successions throughout europe and parts of the arctic suggest that this extinction may have been multi phased with diversity declining over six separate intervals the main phase of decline begins at the pliensbachian toarcian boundary and extends into the lower toarcian to a level that is correlative with the tenuicostatum serpentinum zone boundary to date only the main phase of extinction has been demonstrated as being global in extent and affecting multiple taxonomic groups this multi phased extinction has been attributed to regional and global controlling mechanisms that are associated with the volcanic greenhouse scenario which links the eruption of the karoo ferrar large igneous province lip to global warming and mass extinction we compare stratigraphic ranges of ammonite and foraminiferal species in pliensbachian toarcian successions of western north america to the record in europe and parts of the arctic in order to test the geographic extent of the multiple phases of extinction our results show six intervals of species level decline that correlate with those recognized in europe 1 middle of the lower pliensbachian middle whiteavesi middle freboldi zones 2 middle of the upper pliensbachian upper kunae lower carlottense zone 3 pliensbachian toarcian boundary into the lower toarcian upper carlottense middle kanense zones 4 middle toarcian upper planulata lower crassicosta zones 5 upper middle lower upper toarcian middle crassicosta hillebrandti zones and 6 upper toarcian lower yakounensis zone recognition of this multi phased event in three separate ocean basins paleo pacific paleo arctic and tethys oceans in at least two taxonomic groups greatly expands the known geographic extent of this multi phased event and argues for a controlling mechanism that is global in its reach in relation to the volcanic greenhouse scenario our study shows that four of the six pulses of extinction occur within the main phase of karoo magmatism the decline in the early pliensbachian previously thought to be separate from this event occurs within error range of the onset of karoo magmatism and the decline in the late toarcian coincides with the later stages of magmatism these observations extend the known duration of this multi phased extinction event to the early pliensbachian and support the volcanic greenhouse scenario specifically the eruption of the karoo ferrar lip as a preeminent factor driving the multi phased extinction of the pliensbachian toarcian

the triassic jurassic boundary event from an equatorial carbonate platform ghalilah formation united arab emirates the ghalilah formation uae provides a complete and continuous equatorial shallow water carbonate sequence through the upper triassic to lower jurassic interval in higher latitudes this interval is frequently associated with widespread ocean acidification evidenced by a lack of carbonates or a hiatus in deposition the data presented here in contrast show evidence for aragonite supersaturation at the triassic jurassic boundary in the equatorial tethys 13 c carb shows a characteristic negative excursion with values as low as 2 8 just below the boundary deposition of fossiliferous limestones in this location persisted into the latest rhaetian through the initial negative carbon isotope excursion supplementary material 13 c carb data from bulk rock and a detailed stratigraphic log with sample locations are available at https doi org 10 6084 m9 figshare c 3277283

foraminiferal biostratigraphy and sequence stratigraphy of peritidal carbonates at the triassic jurassic boundary karaburun peninsula western turkey abstract continuous shallow marine carbonates spanning the triassic jurassic boundary are exposed in the karaburun peninsula western turkey the studied section tahtaiskele section consists of upper triassic cyclic shallow marine carbonates intercalated with clastics overlain by lower liassic carbonates based on the microfacies stacking patterns three main types of shallowing upward cycles have been recognized cycles are mostly composed of subtidal facies at the bottom intertidal supratidal facies and or subaerial exposure structures at the top the duration of the cycles suggests that cycles were driven by the precessional milankovitch rhytmicity in the sequence stratigraphic frame of the tahtaiskele section 4 sequence boundaries were detected and globally correlated the first sequence boundary is located at the alaunian sevatian boundary nearly coinciding with the first appearance of triasina hantkeni the second falls in the rhaetian corresponding to a major sea level fall which led to the invasion of forced regressive siliciclastic deposits over the peritidal carbonates the third occurs close to the t j boundary and the fourth lies slightly above the base of the jurassic in the studied section extinction survival and recovery intervals have been recognized based on the stratigraphic occurrence patterns of benthic foraminifera and algae foraminifers became nearly totally extinct in the inner carbonate shelves at the triassic jurassic boundary and an interval of approximately 0 5 my passed before the begining of the recovery of jurassic foraminifera

a 70 million year astronomical time scale for the deep sea bedded chert sequence inuyama japan implications for triassic jurassic geochronology abstract the astronomical time scale ats has provided high resolution geochronology however the early mesozoic ats is still under construction partly due to the lack of continuous pelagic sequences of the early mesozoic here we present ca 70 myr long ats constructed from the early mesozoic deep sea bedded chert sequence exposed in the inuyama area central japan the sedimentary rhythms of bedded chert display a full range of climatic precession related cycles 20 kyr cycle as a chert shale couplet and 100 405 2000 to 4000 and 10 000 kyr cycles as chert bed thickness variation the newly established ats inuyama ats is tuned by 405 kyr eccentricity cycle and is anchored at the end triassic radiolarian extinction level as 201 4 0 2 ma this inuyama ats gives ages consistent with the radiometric ages projected to the inuyama deep sea sequence using biostratigraphy and carbon isotope stratigraphy the inuyama ats provides the age constraints for the triassic and jurassic stage boundaries which support the long norian option of muttoni et al 2004 because the deep sea bedded chert sequence covers a long time interval before the cretaceous the ats for the bedded chert will serve as a template for the astrochronology of mesozoic and older ages

on the onset of central atlantic magmatic province camp volcanism and environmental and carbon cycle change at the triassic jurassic transition neuquen basin argentina abstract the triassic jurassic transition is characterized by the end triassic mass extinction approximately synchronous with the onset of emplacement of the central atlantic magmatic province camp and associated with a major negative carbon isotope excursion cie affecting the ocean atmosphere system here we present new data total organic carbon pyrolysis analysis carbon isotopes from bulk organic matter elemental mercury and other elemental contents from a southern hemisphere triassic jurassic boundary succession in the neuquen basin argentina the end triassic mass extinction there coincides with a relatively small 2 3 negative cie in bulk organic matter and we present a model that suggests that extreme aridity across the western pangaean landmass may have resulted in rather limited terrestrial organic matter flux to the sedimentary realm in eastern panthalassic marine basins hypothetically reducing the magnitude of the observed negative cie in 13ctoc increased deposition of sedimentary hg and hg toc and hg zr in the marine neuquen basin began stratigraphically before the negative cie associated with the end triassic mass extinction and thus before the commencement in north america and africa of camp related basaltic volcanism but possibly coinciding with the early emplacement of camp associated intrusives dykes and sills this relative chronology suggests thermal alteration of intruded country rocks and or intrusive magmatic degassing of hg as potential major sources of elevated hg fluxes to the atmosphere at this time the neuquen basin experienced the development of dysoxic anoxic marine conditions across the triassic jurassic transition enabling increased preservation of organic matter simple mass balance calculations show that enhanced carbon burial rates can explain the inferred evolution of the global exogenic carbon cycle across this time interval

sedimentological palynological and geochemical studies of the terrestrial triassic jurassic boundary in northwestern poland the kamien pomorski ig 1 borehole pomerania nw poland yields a profile through the triassic jurassic t j transition in continental deposits an integrated study of the sedimentology sequence stratigraphy palynology biostratigraphy and geochemistry of these deposits has been carried out on the boundary interval which represents a time of major environmental change two lithological units within the transitional section are distinguished the lower middle rhaetian wielichowo beds of alluvial plain facies which shows evidence of a semi arid climate and the upper rhaetian to lower hettangian zagaje formation lying above a marked erosional sequence boundary composed of mudstone claystone and sandstone deposited in a fluvial lacustrine environment carbon isotope values obtained from palynomaceral separates and thus reflecting isotopic changes in atmospheric co 2 show significant fluctuations through the rhaetian the most conspicuous negative 13 c org excursion is correlated with the rhaetian initial excursion and shows two sub peaks pointing to short term carbon cycle disturbances of lesser magnitude above the initial negative excursion there is a positive excursion followed again by more negative values representing subordinate fluctuation within a positive excursion and is correlated with the t j boundary seventy two miospore taxa have been determined from the studied t j transitional section two major palynological assemblages have been distinguished the lower one typically rhaetian named the cingulizonates rhaeticus limbosporites lundblandii association which corresponds to the rhaetipollis ricciisporites rhaetipollis limbosporites zone and the upper one typically hettangian named the conbaculatisporites mesozoicus dictyophyllidites mortoni cerebropollenites thiergartii association with the age diagnostic pollen c thiergartii which corresponds to the pinuspollenites trachysporites trachysporites heliosporites zone the t j palynofloral turnover occurred in a humid period and is more conspicuous then palynofloral changes observed in greenland the tethyan domain or other parts of ne europe the osmium isotope system is studied herein for the first time from t j continental deposits and shows marked disturbances similar to those measured in marine deposits and attributed to volcanic fallout carbon and osmium isotope correlation and coeval increase in polycyclic aromatic hydrocarbon pah content and darkening of miospores confirm that eruptions of the central atlantic magmatic province camp contributed to the perturbances in climate and crisis in the terrestrial biosphere a series of periodical atmospheric loading by co 2 ch 4 or alternatively by so 2 sulphate aerosols and toxic compounds is inferred to have caused a series of rapid climatic reversals directly influencing the ecosystem and causing the triassic floral crisis a floral turnover period commenced at the initial 13 c excursion with the onset of camp volcanism obtained values of initial 187 os 186 os between 2 905 and 4 873 and very low iridium content about 5 ppt lend no support to a role for an extraterrestrial impact at the t j boundary event the position of the initial negative carbon isotope excursion about 12 m below the t j boundary position of sequence boundaries emergence surfaces and other isotope excursions allow reliable correlation with marine profiles including st audrie9s bay uk csovar hungary and the gssp profile at kuhjoch austria

high resolution ammonite and carbon isotope stratigraphy across the triassic jurassic boundary at new york canyon nevada the triassic jurassic boundary is generally considered as one of the major extinctions in the history of phanerozoic the high resolution ammonite correlations and carbon isotope marine record in the new york canyon area allow to distinguish two negative carbon excursions across this boundary with different paleoenvironmental meanings the late rhaetian negative excursion is related to the extinction and regressive phase the early hettangian 13corg negative excursion is associated with a major floristic turnover and major ammonite and radiolarian radiation the end triassic extinction early jurassic recovery is fully compatible with a volcanism triggered crisis probably related to the central atlantic magmatic province the main environmental stress might have been generated by repeated release of so2 gas heavy metals emissions darkening and subsequent cooling this phase was followed by a major long term co2 accumulation during the early hettangian with development of nutrient rich marine waters favouring the recovery of productivity and deposition of black shales

carbon cycle dynamics following the end triassic mass extinction constraints from paired δ13ccarb and δ13corg records 1 constraining the carbon isotopic changes associated with the end triassic mass extinction is key to understanding the causes of the extinction and dynamics of recovery from it yet the pattern and timing of 13c variation surrounding the extinction remain poorly constrained here we present close to 1000 new 13c measurements from six newly sampled sections in italy we observe a sharp negative excursion in 13ccarb coincident with the disappearance of the triassic fauna and two positive excursions above it the negative 13ccarb excursion in these sections does not occur in 13corg suggesting a possible diagenetic origin in contrast the interval of elevated 13c occurs in both carbonate and organic carbon suggesting that it is likely to be a primary feature the positive excursions in the lombardy basin southern alps and mt cefalo southern apennines appear to be time correlative on the basis of their position above the disappearance of characteristically triassic biota however it is less certain that they are time correlative with positive excursions in other sections worldwide as few options exist that honor both bio and chemostratigraphy nonetheless similarity to other events that are interpreted as global as well as carbon cycle considerations suggest that the isotopic enrichment is best interpreted to reflect a shift in the isotope composition of the global surface carbon reservoir our data indicate that perturbation of the global carbon cycle was not confined to the immediate vicinity of the extinction interval but rather persisted for substantial length of geologic time afterwards

the last 140 ka in the afro asian arid semi arid transitional zone abstract during the last ten years a great number of geological or other proxy records provided radiocarbon u th or tl dated information on the past climatic oscillations in the arid semi arid zones extending between the atlantic and the pacific comparisons and a synthetic view of these results can now be attempted for the last 140 ka and compared with global changes as registered in oceanic or ice cores and with palaeomonsson models for this purpose wide spatial and time scales have to be used on the whole arid humid alternations roughly fit global changes cold phases corresponding to an extension of the arid areas to the south warm phases corresponding to the shrinking of the same to the north the last interglacial is associated with an increase of precipitation throughout the area considered isotopic stage 4 brings no evidence whatsoever of humid conditions two wetter episodes are registrated during stage 3 a major rainfall decrease is everywhere associated with the last glacial maximum 21 15 ka in most regions the arid or semi arid zones extending several hundred kilometers southwards relative to the present day pattern the two abrupt deglaciation steps and the younger dryas are recorded in all of the most sensitive regions at the margins of the present day monsoonal range during the holocene the precipitation increases everywhere by 100 400 mn relative to the present day values the optimum being at 8 5 6 5 ka a climatic deterioration follows with an irregular pattern of dry wet episodes according to the different geographic conditions the humid phase terminates at 3 5 3 ka in the whole transitional zone the major southward shift of the monsoonal precipitation range since its optimum some 8000 years ago fits the astronomical neoglacial trend and may possibly be correlated with past stage 5d although its rapidity and spatial importance may just reflect one of the sharp successive cold warm variations registered by grip during the whole stage 5

carbon cycle perturbation and stabilization in the wake of the triassic jurassic boundary mass extinction event 1 the triassic jurassic boundary mass extinction event t j 199 6 ma is associated with major perturbations in the carbon cycle recorded in stable carbon isotopes two rapid negative isotope excursions in bulk organic carbon 13corg occur within the immediate boundary interval at multiple locations and have been linked to the outgassing of 12c enriched co2 from the central atlantic magmatic province in british columbia a positive 13corg excursion of 5 vienna peedee belemnite v pdb spans part or all of the subsequent hettangian stage here we examine the significance of these carbon isotope excursions as records of global carbon cycle dynamics across the t j boundary and test the link between carbon cycle perturbation stabilization and biotic extinction recovery patterns a combination of 13corg and palynological analyses from the late triassic to early jurassic in the mingolsheim core germany suggests that organic carbon isotope variations are best explained as the result of both compositional changes in terrestrial versus marine input and disturbance and recovery patterns of major terrestrial plant groups across the t j boundary a new high resolution 13ccarb record from the val adrara section in the southern alps italy spanning from the uppermost rhaetian through lower sinemurian does not exhibit a negative excursion at the t j boundary but does record a large positive 13ccarb excursion of 4 v pdb in bulk carbonate that begins at the t j boundary and reaches a local maximum at the early late hettangian boundary values then gradually decrease reaching 0 5 at the hettangian sinemurian boundary and remain relatively constant into the early sinemurian complementary 13ccarb data from 4 more sections that span the hettangian sinemurian boundary support carbon cycle stabilization within the upper hettangian our analyses suggest that isotope changes in organic carbon reservoirs do not necessarily require a shift in the global exogenic carbon reservoir and that the positive excursion in the carbonate carbon isotope record is best explained as the combined result of an increase in atmospheric pco2 leading to accelerated carbon cycling decreased skeletal carbonate production and increased organic carbon burial lasting several hundred thousand years the termination of the positive inorganic carbon isotope excursion coincides with the recovery of marine skeletal carbonate producers and coeval changes in terrestrial vegetation and reflects the gradual reduction in pco2 and the stabilization of the global carbon cycle during the sinemurian

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

geochemistry of the end permian extinction event in austria and italy no evidence for an extraterrestrial component the end permian mass extinction 251 ma was the largest in earth s history and the great extent of biospheric perturbation is recorded as dramatic shifts in carbon isotope ratios of sedimentary materials both terrestrial and extraterrestrial events are commonly invoked as causative mechanisms for the crisis and the primary reason for the event remains the subject of controversy geochemical indicators sensitive to the influence of extraterrestrial material involve platinum group elements and osmium and helium isotope ratios analyses of extinction levels in two sections from austria and italy reveal no evidence of an extraterrestrial impact the end permian crisis it appears was a homegrown catastrophe

episodic photic zone euxinia in the northeastern panthalassic ocean during the end triassic extinction severe changes in ocean redox nutrient cycling and marine productivity accompanied most phanerozoic mass extinctions however evidence for marine photic zone euxinia pze as a globally important extinction mechanism for the end triassic extinction ete is currently lacking fossil molecular biomarker and nitrogen isotopic records from a sedimentary sequence in western canada provide the first conclusive evidence of pze and disrupted biogeochemistry in neritic waters of the panthalassic ocean during the end triassic increasing water column stratification and deoxygenation across the ete led to pze in the early jurassic paralleled by a perturbed nitrogen cycle and ecological turnovers among noncalcifying groups including eukaryotic algae and prokaryotic plankton if such conditions developed widely in the panthalassic ocean pze might have been a potent mechanism for the ete

climate change driven black shale deposition during the end triassic in the western tethys abstract several new triassic jurassic boundary sections from the eiberg basin northern calcareous alps austria have been studied at high resolution we present integrated geochemical and biological proxy data from this western tethys shelf basin high resolution correlation of kuhjoch the global boundary stratotype section and point gssp for the base of the jurassic hochalplgraben and tiefengraben shows that the initial and main carbon isotope excursions cie are contemporaneous with first and last occurrences of boundary defining macro and microfossils we focus on the end triassic initial cie at the transition from the limestones of the kossen formation to the marls of the kendlbach formation this change coincides with a dramatically increased influx of conifer cheirolepidiaceae pollen and increased total organic carbon toc values succeeded by an acme of green algae cymatiosphaera we present a model in which increased terrestrial organic matter influx is related to enhanced seasonality and increased erosion of the hinterland reduced salinity of the surface waters led to the mass occurrence of green algae stratification of the water column may have caused anoxic bottom water conditions and black shale deposition during the initial cie at the base of the kendlbach fm