the schilfsandstein and its flora arguments for a humid mid carnian episode recently intensified research on the mid carnian episode stimulated discussions about the mid carnian climate and a supposed humid climate shift this basin scale study on the schilfsandstein the type example of the mid carnian episode applied sedimentological palynological and palaeobotanical proxies of the palaeoclimate to a large dataset of cored wells and outcrops the results demonstrate the primary control of circum tethyan eustatic cycles on the central european basin where transgressions contributed to basin scale facies shifts the palaeoclimate proxies point to a uniform arid to semi arid carnian climate with low chemical weathering and high evaporation consequently transgressions into the central european basin led to increased evaporation forcing the hydrological cycle the increased runoff from source areas resulted in high groundwater stages on lowlands characterized by hydromorphic palaeosols and intrazonal vegetation with hygrophytic elements during lowstands reduced evaporation and runoff led to increased drainage and desiccation of lowlands characterized by formation of vertisols calcisols and gypsisols and zonal vegetation with xerophytic elements the proposed model of sea level control on the hydrological cycle integrates coeval and subsequent occurrences of wet and dry lowlands hydromorphic and well drained palaeosols and intrazonal and zonal vegetations thus the schilfsandstein does not provide arguments for a humid mid carnian episode supplementary material datasets of palynomorph eco group peg and macroplant eco group meg analyses are available at https doi org 10 6084 m9 figshare c 4182593

a rise in the carbonate compensation depth of western tethys in the carnian late triassic deep water evidence for the carnian pluvial event the upper triassic of the lagonegro basin southern apennines southern italy is represented by hemipelagic cherty limestones of the calcari con selce formation deposited in an oceanic setting two stratigraphic sections petina chiana and pignola 2 representative of the evolution of the lagonegro basin during the carnian have been studied in detail with a multidisciplinary approach in the pignola 2 section within the calcari con selce formation a unique interval composed of green shales and radiolarites has been identified the absence of carbonate deposition within this interval is interpreted as evidence of a contemporaneous shallowing of the carbonate compensation depth conodont and palynomorph biostratigraphy constrain the age of this interval to the julian tuvalian lower carnian upper carnian boundary the age and characteristics of this interval suggest correlation with a putative climatic event known as the carnian pluvial event which has also been recognized in continental and shallow marine successions from different european localities this event is thus now documented also in a deep marine setting like the continental and shallow water settings it is characterized by a sudden input of siliciclastics petina chiana and pignola 2 integrate current knowledge of the carnian distribution of conodonts paragondolella praelindae kozur to date known only from the lower tuvalian has now been documented from the uppermost julian moreover a drastic turnover was recorded between julian and tuvalian conodont assemblages which is clearly associated with the carnian pluvial event thus a biotic crisis oceanographic changes associated with the rise of the carbonate compensation depth increased rainfall and an anomalous siliciclastic input occur contemporaneously at the time of the carnian pluvial event a similar pattern is associated with perturbations of the carbon cycle that occur during the jurassic and cretaceous e g in the early aptian thus it is hypothesized that the carnian pluvial event may have analogous causes

contributions of wind forcing waves and surface heating to sea surface height observations in the pacific ocean the dominant processes affecting sea surface height ssh variability observed by the topex poseidon altimeter vary regionally in the pacific baroclinic rossby waves equatorially trapped kelvin waves steric response to seasonal heating and the response to wind stress curl forcing are all important the steric response to surface heating dominates seasonal ssh variability in the subpolar gyre and the eastern subtropical gyre south of the kuroshio extension and south of 20 n in the eastern pacific the dominant contribution to ssh is from near annual period rossby waves to quantify the wave energy observed ssh was assimilated into a kinematic model of westward propagating waves these waves account for 70 of ssh variance between 10 s and 10 n but only 30 between 10 n and 30 n although wave energy in the eastern pacific is correlated with ssh anomalies at the equator the much larger wave energy in the western pacific is correlated with wind stress curl suggesting that the rossby waves there are locally forced in addition to these planetary waves the ocean response to wind forcing via ekman pumping is observed in several places specifically in the north equatorial current a quasi steady topographic sverdrup balance is detectable over most of the north pacific at latitudes as low as 10 15 n as well as in the south pacific where it is seen north of 50 s the decomposition of the ssh signal into propagating waves an ekman pumping response and sverdrup transport is consistent with the results from an isopycnal numerical model

propagation characteristics of extratropical planetary waves observed in the atsr global sea surface temperature record this paper examines the characteristics of planetary wave signatures that have been found in the along track scanning radiometer averaged sea surface temperature asst record for 1991 1996 longitude time plots for every latitude between 5 and 50 north and south reveal westward propagating wave like patterns at many locations whose speed decreases with latitude like baroclinic rossby waves a two dimensional radon transform method is used to measure the wave speed and its variation with location and time which broadly matches the rossby wave speeds predicted by the most recent theory and those measured by topex altimetry although there are some discrepancies at low latitudes the thermally detected speeds are slower than expected a possible consequence of sampling limitations wave signatures are clearest between 25 and 40 s where the meridional temperature gradient is strongest here observed speeds are 20 30 greater than theoretical predictions planetary wave speed varies considerably with longitude in general it increases toward the west of ocean basins and distinct differences between ocean basins are evident the propagation characteristics of the waves appear to change abruptly at locations consistent with latitudinal variations in seafloor bathymetry particularly midocean ridges in addition eastward propagating signatures are found in the southern ocean the results demonstrate the value of the asst data set as a tool for studying basin scale wave processes as a complement to the use of altimetry by observing the thermal signature of rossby waves the method has the potential to clarify their influence on air sea interaction processes and to contribute to climate modeling studies

do eddies ride on rossby waves both vortices and baroclinic rossby waves show up as westward propagating features in the sea surface height anomaly ssha records when displayed in the form of zonal temporal or hovmoller diagrams a chain of filters was used to separate the ssha into orthogonal components each of the filtered components was then reassembled as a set of maps in the maps of individual components we clearly see westward propagating rossby waves our most striking findings are i limited within their critical latitudes the wave extrema coincide with a significant number of vortices ii eddy wave coincidence occurs at a preferred latitude that depends on the wave period iii among the vortices that at some point of their existence coincide with a wave a relatively large percentage of them remained their whole lifetime with the wave and iv a mechanism is proposed to explain why eddies tend to remain over the wave extrema crests and troughs our answer to the title question is yes they often do

temporal variation of meandering intensity and domain wide lateral oscillations of the gulf stream the path of the gulf stream exhibits two modes of variability wavelike spatial meanders associated with instability processes and large scale lateral shifts of the path presumably due to atmospheric forcing the objectives of this study are to examine the temporal variation of the intensity of spatial meandering in the stream to characterize large scale lateral oscillations in the stream s path and to study the correlation between these two dynamically distinct modes of variability the data used for this analysis are path displacements of the gulf stream between 75 and 60 w obtained from avhrr derived advanced very high resolution radiometer infrared images for the period april 1982 through december 1989 meandering intensity measured by the spatial root mean square displacement of the stream path displays a 9 month dominant periodicity which is persistent through the study period the 9 month fluctuation in meandering intensity may be related to the interaction of rossby waves with the stream interannual variation of meandering intensity is also found to be significant with meandering being much more intense during 1985 than it was in 1987 annual variation however is weak and not well defined the spatially averaged position of the stream which reflects nonmeandering large scale lateral oscillations of the stream path is dominated by an annual cycle on average the mean position is farthest north in november and farthest south in april the first empirical orthogonal function mode of the space time path displacements represents lateral oscillations that are in phase over the entire study domain interannual oscillations are also observed and are found to be weaker than the annual oscillation the eigenvalue of the first mode indicates that about 21 5 of the total space time variability of the stream path can be attributed to domain wide lateral oscillations the correlation between meandering intensity and domain wide lateral oscillations is very weak

late triassic and early jurassic palaeogeography of the world abstract a new version of global and regional palaeogeographic maps is presented for two time intervals these maps depict the plate tectonic configuration palaeoenvironment and lithofacies during the late triassic carnian norian and early jurassic hettangian toarcian time the individual maps illustrate the general conditions present during the maximum marine transgressions of higher frequency cyclicity within the absaroka sequence of sloss during triassic time pangaea began to stretch initiating the rifting and future break up of the supercontinent the continued northward drift of the cimmerian continent corresponded with the progressive closure and consumption of palaeotethys oceanic crust and the opening of the neotethys ocean the most significant late triassic convergent event was the indosinian orogeny occurring as a result of the consolidation of south china and north china blocks also indochina and indonesia were sutured to south china at the same time the qiangtang block approached the eurasian margin the consolidation of the north chinese and amurian blocks left open a large embayment of panthalassa between amuria and laurasia the so called mongol okhotsk ocean active subduction existed along the margin of this ocean dipping cratonwards towards east siberia the last collisional events of the uralian orogeny took place during the triassic and early jurassic time the conclusion of the uralian orogeny was accompanied by uplift of the adjacent areas of eastern europe and western siberia during the early jurassic the palaeotethys ocean was finally closed and the cimmerian continent collided with asia causing the cimmerian orogeny the time around the triassic jurassic boundary marked an important biotic extinction event plate tectonic activity caused palaeogeographic and palaeoclimatic change which may have contributed to the mass extinction from the plate tectonic and palaeogeographic point of view the following events could have influenced the extinction 1 the closure of palaeotethys and assembly of the asian part of pangaea 2 the break up of pangaea in the future central atlantic area and transition from rifting to drifting and 3 the very extensive basaltic volcanism of the central atlantic magmatic province

the aftermath of the cpe and the carnian norian transition in northwestern sichuan basin south china the northwestern sichuan basin south china was a portion of eastern tethys where during the late triassic a sharp lithological transition from oolitic bioclastic limestones and sponge reef mounds to dark grey terrigenous clays siltstones and sandstones is visible in several localities the timing and significance of this major facies transition is still unclear here we report new biostratigraphic and carbon stable isotope data from hanwang and jushui northwestern sichuan basin sporomorphs ammonoids conodonts and halobiid bivalves show that the lithological change is late carnian to early norian in age this amended age determination facilitates recalibration of the magnetostratigraphy in the area allowing correlation between the late triassic of the sichuan basin and the astrochronostratigraphic polarity time scale a carbon stable isotopic perturbation across the carnian norian boundary cnb is missing in our sections or it is concealed because of the mixed organic matter sources our findings pinpoint the position of the cnb to a short stratigraphic interval of c 12 m thickness in the sichuan basin the studied sections greatly extend the palaeogeographical documentation of the cnb and provide novel information on biostratigraphy and chemostratigraphy that should be considered in defining the best position of the norian global stratotype section and point

triassic climates state of the art and perspectives abstract the climate of the triassic period was characterized by a non zonal pattern dictated by a strong global monsoon system with effects that are most evident in the tethys realm this strong monsoonal regime is related to the aggregation of the pangaean supercontinent which by triassic time was already completed climate oscillations existed within this framework the harsh hot house climatic conditions that characterized the late permian and perhaps precipitated the end permian mass extinction were probably maintained during the early triassic and may account for the impoverished but distinctive faunal and floral lower triassic associations although metazoan reef builders were probably the most affected group carbonate production remained high at least in the western tethys realm the middle triassic was characterized locally by humid episodes although their geographical distribution has yet to be clarified the carnian pluvial event marks an episode of increased rainfall documented worldwide was the most distinctive climate change within the triassic different hypotheses have been proposed for its causes changes of atmospheric or ocean circulation driven by plate tectonics a peak of the global monsoon due to maximum continent aggregation or triggering by the eruption of a large igneous province subsequently the late carnian and norian seem to have been climatically stable although minor climatic changes have recently been described even from this time period finally the end triassic extinction event is also associated with climate change specifically warming and increased rainfall but this evidence comes mostly from the northern parts of the central atlantic magmatic province and the global pattern of climate change at the triassic jurassic boundary has still to be resolved many facets of triassic climate are intriguing and deserve further research however palaeoclimate studies on the triassic have so far been carried out only locally with different proxies those proxies will require inter calibration in order to depict correctly the temporal and geographical patterns of triassic climate

on too fast baroclinic planetary waves in the general circulation abstract recent altimetric observations of the ocean surface reveal signatures of long planetary waves near the annual frequency band comparisons of the observed wave speeds and those predicted by standard linear theory suggest that the latter is inadequate as it yields different westward speeds than those measured in the extratropical latitudes the predicted speeds are typically slower than the observations here the problem of long baroclinic wave propagation in a forced stratified ocean is considered theoretically with a view toward explaining these observations of too fast planetary waves from a quasigeostrophic analysis it is argued that baroclinic waves in a sheared environment are accelerated to the west via their interactions with both the mean advective field and the mean potential vorticity field conditions under which the ratio of actual to linear phase speeds matches the observed ratio are computed and found to be typical of the open ocean extensions of these ideas to continuously st

the carnian pluvial event in western europe new data from iberia and correlation with the western neotethys and eastern north america nw africa regions abstract at the beginning of the late triassic a period of increased precipitation occurred over large tracts of central pangea the carnian pluvial event it was a short lived event 1 ma coeval with a marked sea level fall and active rifting new and classical sections of carnian age in the iberian peninsula have been studied and a new correlation scheme is proposed for the iberian domain integrating field data and subsurface electric log data this is the first time that the portuguese and spanish late triassic carnian sediments are correlated the carnian pluvial event is identified in the iberian peninsula as a continental clastic wedge manuel fm and coeval sediments in between marine evaporite formations during a marked sea level drop event its age is considered to be julian early carnian by palynological and paleogeographic considerations a new correlation of the late triassic sediments of the iberian peninsula with coeval sediments of western europe nw africa and eastern north america is proposed and a new paleogeographical map of central eastern pangea for this period is presented in order to demonstrate that the geographical extent of the siliciclastic sediments related to the carnian pluvial event was much larger than accepted before

palaeoenvironmental controls on the clay mineralogy of carnian sections from the transdanubian range hungary abstract the upper triassic sediments both in nw europe and in the mediterranean region imply a generally arid climate regime in the carnian however a humid phase with a high input of siliciclastics is assumed carnian pluvial event but its causes are still highly controversial the carnian marine succession of the transdanubian range tr hungary also shows a significant change in sedimentation pelagic carbonate deposition fured limestone formation was followed by the formation of marly sediments veszprem marl and sandorhegy formations in order to understand the environmental changes the clay mineralogy of 240 carnian samples determined by x ray diffraction is discussed in the present paper additionally this set of clay mineral data from four boreholes from the bakony hills bakonysz cs bszu 1 balaton highland balatonfured bfu 1 mencshely met 1 and zsambek basin zsambek zs 14 allows us to test the reliability of clay minerals as palaeoclimatic proxies for the carnian late triassic by reconstructing spatial and temporal variations the first increase in clay content of the studied carnian succession can be detected in the limestone marl couplets of the cordevolian fured limestone its clay fraction is dominated by illite mixed layer illite smectite is and chlorite without kaolinite a good indicator of landmasses with a hot climate and constant humidity thus this compositional change probably related to a sea level drop subsequently the clay mineral assemblages of the veszprem marl sections in the bakony hills and the balaton highland are composed of illite poorly ordered r 0 is with 60 70 expandable component chlorite and kaolinite on the other hand the clay fraction of the samples from the zsambek basin is composed of illite is with an average of 40 50 expandable component and a transitional r 0 to r 1 type of ordering and kaolinite chlorite does not occur in the early julian kaolinite enrichments 10 20 in the clay fraction can be regarded as a manifestation of the climate shift from the prevailing aridity to the more seasonal climate with enhanced humid season the overall presence of abundant illite and accompanying chlorite can indicate a high rate of erosion of moderately weathered rocks while the large amount of smectitic clay transformed to is could be partly derived from transport of weathering products from a distant source area and subordinately from diagenetic alteration of intermediate to basic volcanic rocks spatial variation in the expandability and ordering of the is at least partially could be caused by different degree of the diagenetic overprint

environmental control on the end of the dolomia principale hauptdolomit depositional system in the central alps coupling sea level and climate changes abstract the norian in the western tethys is characterised by the deposition of early dolomitised inner platform facies dolomia principale hauptdolomit dp hd bordered on the landward side by terrigenous coastal deposits keuper and on the seaward side by calcareous backreef and reefal facies dachstein limestone passing basinward to open sea sediments hallstatt facies the inner carbonate platform is locally lombardy basin carnic alps central austroalpine dissected by normal faults leading to the development of intraplatform troughs close to the norian rhaetian boundary sedimentation records an abrupt environmental change both on platform top and basins all over the western tethys e g western carpathians transdanubian range alps central apennine the top of the dolomia principale locally emerged reflecting a major eustatic sea level fall emersion is recorded in favourable settings by the development of polycyclic paleosols up to 30 m thick in the norian intraplatform basins the succession is capped by 4 to 8 m of thin bedded fine grained limestones yielding abundant remnants of fishes and terrestrial reptiles fossil concentration as well as sedimentological features is indicative of reduced sedimentation rates due to decreased carbonate production induced by the emersion of the platform top the sea level fall was followed by deposition of mixed fine grained siliciclastic carbonate successions e g riva di solto shale kossen beds rhaetavicula contorta beds fatra formation stratigraphic evidence indicates a dry climate in the western tethys during the norian as indicated by the presence of evaporites burano apennine and arid to semi arid coastal to playa settings upper keuper germany in contrast the basal layers of the basinal shales show evidence of wet climate the end of the norian depositional system records two different phenomena 1 an important sea level fall was responsible for the emersion of the platform top and deposition of a condensed horizon in the basins and 2 transition from dry to humid climate the observed evolution is explained with a global cooling which caused the rapid sea level fall responsible for the abrupt end of the dp hd depositional system and the shift of the boundary between arid and temperate climate belts which modified the distribution and amount of rainfall triggering the deposition of shales along the western tethys margin

climate variability during the carnian pluvial phase a quantitative palynological study of the carnian sedimentary succession at lunz am see northern calcareous alps austria abstract the middle and upper triassic prevailing dry climate was interrupted by a global phase of increased humidity during the early carnian the carnian pluvial phase cpp it started at the julian 1 2 boundary and lasted approximately until the latest julian or early tuvalian in the tethys this is reflected by a change from limestone deposits to first organic rich mudstones and then to siliciclastics the cpp occurred along the northern rim of the tethys and is reported from many locations within and surrounding europe in this study samples from lunz am see in austria were analyzed for palynology and for bulk carbon isotope values covering a 450 m thick succession a known 3 bulk organic carbon isotope excursion possibly as a result of the eruption of large amounts of volcanogenic material in the gostling member and the basal reingraben formation has been confirmed a total of five distinctive palynology assemblages were recognized and correlated regionally while the under and overlying formations yield terrestrial and subordinate also marine palynomorphs the palynoflora of the lunz formation is near wholly terrestrial in origin climate trends were inferred from multivariate statistical analysis pca of the palynofloral record palynomorphs show a general trend from a dry climate during the julian 1 to wetter conditions during the julian 2 the wetter conditions were periodically interrupted by shorter periods of dryer climate in terms of temperature trends the climate was warmer during the early julian 2 which corresponds with the deposition of the reingraben formation temperature decreased again and remained fairly stable during most of later part of the julian 2 which corresponds to the deposition of the lunz formation this study correlates with similar observations from other locations from the western tethys region that support the theory of a wide ranging to global carnian pluvial phase

palynology and the eco plant model of peat forming wetlands of the upper triassic haojiagou formation in the junggar basin xinjiang nw china abstract terrestrial deposits of the triassic jurassic transition are well developed in the junggar basin located in the haojiagou valley of urumqi xinjiang uygur autonomous region of northwest china this paper describes the palynology of a 10 m thick lignite bed from the upper triassic haojiagou formation rhaetian with the aim of reconstructing the palaeovegetation and palaeoenvironment of a peat forming wetland near the triassic jurassic boundary the palynoflora contains both eurasian and gondwanan elements and is dominated by the spores and pollen of bennettitales corystospermales ginkgoales and gleicheniales at the triassic jurassic boundary hettangian the palynoflora significantly changes as cyatheales spores become the dominant elements we analyze assemblages in terms of an eco plant model which assigns the parent plants of the palynomorphs into five groups based on humidity and four groups based on temperature and uses multivariate statistical analyses to infer palaeoclimate and palaeoenvironmental conditions results suggest that the palaeoclimate of the rhaetian was generally wet and subtropical with short seasonal drought periods our analysis shows that an eco plant model may be a useful tool to reveal past vegetation patterns and climate changes applicable to other mesozoic assemblages

long period transport changes in the eastern north atlantic and their simulation by propagating waves an analysis is presented of geostrophic volume transport across a zonal line along 28 degrees n in the eastern atlantic the data are from an array of five moorings with 200 km spacing carrying temperature sensors and one current meter each for 1 or 2 years transport changes in the main thermocline relative to a fixed depth level are obtained by the use of temperature salinity relationships the transport variability is simulated by two propagating waves with first order baroclinic mode structure solutions exist with annual and semi annual periods and zonal wavelengths of 100 200 km and 300 km respectively assuming quasi geostrophic dynamics and using results on the reynolds stress the dominating waves of annual and semi annual period are found to propagate to the southwest with 45 degrees 60 degrees and 25 degrees to the south off the westward direction respectively wave solutions with a 90 day period and a zonal wavelength of about 300 km are interpreted as an effect of barotropic waves arising due to horizontal temperature inhomogeneity the propagation is about 25 degrees off the westward direction in general good approximations are obtained with the propagating wave simulations in the western and central part of the array while large differences occur between observation and simulation close to the canary archipelago possible causes for these differences are discussed

changes in the hydrological cycle in tropical east africa during the paleocene eocene thermal maximum the paleocene eocene thermal maximum petm at ca 55 8 ma is one of the most studied instances of past greenhouse gas induced global warming as such it provides a rich opportunity to examine the impact of such global change on local climates the effects of increased continental and sea surface temperatures on local precipitation and humidity during the petm remain poorly constrained and studies reveal complex regional differences whilst some localities appear to experience a net increase in humidity others exhibit the opposite crucially there are few records of hydrological change from tropical regions recent onshore drilling expeditions in tanzania have yielded expanded sedimentary sections deposited in a marine environment that span much of the late cretaceous and paleogene and show exceptionally good preservation of both calcareous microfossils and organic matter the petm interval has previously been constrained by both biostratigraphy and carbon isotopic records and spans ca 7 m of section lipid distributions including various terrestrial marine and bacterial biomarkers and their hydrogen isotopic compositions as well as mineralogy were used to examine east african vegetation and hydrological responses to the global change occurring at the petm although total organic carbon contents decrease the concentrations of both higher plant n alkanes n alkanoic acids and soil bacterial glycerol dialkyl glycerol tetraethers biomarkers increase dramatically at the onset of the petm negative carbon isotope excursion cie suggesting an increased discharge of fluvial sedimentary organic matter similarly mineralogical indicators of terrestrial input including ti al and si al ratios quartz contents and notably the proportion of kaolinite also increase at the onset of the cie however higher plant leaf wax n alkanes c27 c29 and c31 become more deuterium enriched throughout the same interval suggesting a more arid and or hotter rather than a more humid environment this evidence collectively suggests an east african early petm climate characterised by overall hot and arid conditions punctuated by intense perhaps seasonal precipitation events these data match observations from other locations at mid latitudes suggesting that the humid climate often suggested for the petm was not globally widespread

multiple negative carbon isotope excursions during the carnian pluvial episode late triassic abstract the carnian pluvial episode was a phase of global climatic change and biotic turnover that occurred during the early late triassic in marine sedimentary basins the arrival of huge amounts of siliciclastic sediments the establishment of anoxic conditions and a sudden change of the carbonate factory on platforms marked the carnian pluvial episode the sedimentary changes are closely associated with abrupt biological turnover among marine and terrestrial groups as for example an extinction among ammonoids and conodonts in the ocean and a turnover of the vertebrate fauna and the flora on land multiple negative carbon isotope excursions were recorded during the carnian pluvial episode in both organic matter and marine carbonates suggesting repeated injection of 13c depleted co2 into the ocean atmosphere system but their temporal and causal links with the sedimentological and palaeontological changes are poorly understood we here review the existing carbon isotope records and present new data on the carbon isotope composition of organic carbon in selected sections of the western tethys realm that record the entire carnian pluvial episode new ammonoid conodont and sporomorph biostratigraphic data were collected and coupled to an extensive review of the existing biostratigraphy to constrain the age of the sampled sections the results provide biostratigraphically constrained composite organic carbon isotope curves for the carnian which sheds light on the temporal and causal links between the main carbon isotope perturbations and the distinct environmental and biotic changes that mark the carnian pluvial episode the carbon isotope records suggest that a series of carbon cycle perturbations possibly recording multiple phases of volcanic activity during the emplacement of the wrangellia large igneous province disrupted carnian environments and ecosystems repeatedly over a remarkably long time interval of about 1 million years

discovery of a major negative δ13c spike in the carnian late triassic linked to the eruption of wrangellia flood basalts major climate changes and mass extinctions are associated with carbon isotope anomalies in the atmosphere ocean system and have been shown to coincide with the onset of large igneous provinces lips and by association their emissions of greenhouse gases and aerosols however climatic and biological consequences of some known lip eruptions have not yet been explored during the carnian late triassic large volumes of flood basalts were erupted to form the so called wrangellia lip western north america this huge volcanic province is similar in age to a major climatic and biotic change the carnian pluvial event cpe but no evidence of a causal relationship exists other than timing here we report a sharp negative 13 c excursion at the onset of the cpe recorded in organic matter an abrupt carbon isotope excursion of 4 occurs in terrestrial and marine fossil molecules whereas total organic carbon records an 2 shift we propose that this carbon isotope negative shift was caused by an injection of light carbon into the atmosphere ocean system linked to the eruption of wrangellia flood basalts this carbon cycle perturbation occurs slightly before two major evolutionary innovations the origin of dinosaurs and calcareous nannoplankton

the middle carnian wet intermezzo of the stuttgart formation schilfsandstein germanic basin abstract the middle carnian wet intermezzo mcwi of the stuttgart formation schilfsandstein and age equivalent strata of the northwestern tethys occurred entirely within equivalents of the upper subzone of the austrotrachyceras austriacum ammonoid zone of the late julian its duration is estimated to be only about 0 7 0 8 myr in both the germanic basin and the northwestern tethys the warm climate during the mcwi was characterized by a rate of precipitation that exceeded somewhat the evaporation but was not so great as to be pluvial the mcwi was related to the atmospheric circulation of a megamonsoonal system that was characterized by strong moisture laden northwesterly flowing trade winds that rose as they reached the estimated 2000 3000 m high eastern shoulder uplift of a huge rift causing them to drop an extraordinary amount of rain this eastern shoulder uplift lay within the caledonides of modern day western scandinavia this region only between 30 and 50 n palaeolatitude had a truly pluvial climate and the huge amounts of fresh water dropped there transported large amounts of siliciclastics from this rift shoulder uplift southward into the germanic basin before deposition of the siliciclastics an early julian eustatic sea level fall caused widespread erosion in the germanic basin in the later part of late julian a transgression from the eastern gates with the concurrent strong fresh water influx from the north flooded the centre of the northern germanic basin with a shallow brackish sea in which the osterhagen horizon basisschichten of the lower stuttgart formation was deposited in the upper osterhagen horizon the salinity rapidly decreased from mesohaline through mio and oligohaline to fresh water levels in southern germany the basisschichten formed entirely within fresh water or very low salinity brackish environments later a slight subsidence of the southwestern germanic basin shifted the main outflow of fresh water toward the southwestern end of the basin creating local brackish conditions in the northern marginal part of the northwestern tethys e g in the lunz beds during this time interval tidal influence also can be found in the stuttgart formation deposited in palaeoestuaries of the southwestern germanic basin adjacent to the tethys the very strong fresh water influx from the north however prevented these estuaries from developing a strongly elevated salt content so that only fresh water to oligohaline brackish faunas are found there such as the eberstadt bivalve conchostracan fauna at the base of the tuvalian the megamonsoonal system either disintegrated or else the trade winds shifted their principal flow direction this caused the climate within the germanic basin and in the nearby northwestern tethys sea to become arid again as it had been before the deposition of the stuttgart formation these changes in the atmospheric circulation patterns also terminated the pluvial climatic regime to the north along the scandinavian eastern rift shoulder uplift this in turn ended the transport of huge amounts of siliciclastics from this region southward into the germanic basin and ended the deposition of the schilfsandstein after this the hypersaline sabkha and playa sedimentation of the weser formation began which was accompanied by some minor marine ingressions in the southwestern germanic basin

climate variations in the boreal triassic inferred from palynological records from the barents sea this paper presents palynological evidence from the late early triassic late smithian to the late triassic rhaetian of the barents sea area a continuous palynological succession from an exploration well 7228 7 1a in the nordkapp basin sw barents sea and palynological data from a series of shallow cores drilled at the svalis dome central barents sea representing selected triassic intervals these fully marine sediments are independently dated by marine faunas both records show significant shifts in the distribution of the main floral elements changing ratios of spore pollen taxa grouped as hygrophytes versus xerophytes and spores versus pollen reveal major changes of the floras within the studied interval one distinct turnover coincides with the smithian spathian boundary where lycopsid and pteridophyte spores dominated assemblages change to pollen pteridosperms and conifers dominated assemblages lower middle triassic assemblages are again dominated by lycopsid spores while the assemblages from the upper part of the middle triassic and the lower part of the late triassic are characterised by dominance of coniferous pollen and show the decline of pteridosperms in the latest triassic fern spores are abundant and diverse in contrast to the middle triassic the pollen assemblages are characterized by cycadophytes and araucariacites these distribution patterns are interpreted to reflect climatic changes the presented results from norwegian boreal areas confirm the significant differences between quantitative distribution of specific taxa as well as diversity of major groups in plant assemblages from low and mid latitudes the present survey opens new perspectives for more detailed comparisons and climatic interpretations of floras from the triassic period a time during which mesozoic vegetation established the major changes in the dominance of specific floral elements especially the diversification and spreading of the conifers can probably be related to climatic changes

palynological correlation of carnian humid pulses throughout western tethys abstract the carnian pluvial event is an upper triassic swing toward increased rainfall best documented in the tethys tropical belt and mainly recognized on its effects on sedimentary systems as the demise of carbonate platforms and the enhanced siliciclastic supply in some portions of western tethys and particularly in the raibler schichten of the northern calcareous alps and in the dolomites the carnian pluvial event is recorded by four discrete siliciclastic pulses in the raibler schichten three siliciclastic intervals are documented and take the name of first second and third shale in order to correlate these pulses at the basinal scale the study of the palynological assemblages in a section of the raibler schichten near rubland austria and of the classical succession of the lunz nappe have been carried out more than eighty palynomorph species are recorded most of them correspond to typical carnian morphospecies of the carnian pluvial event in europe on the base of their stratigraphic distribution three different palynomorph assemblages are described aulisporites astigmosus assemblage lagenella martinii assemblage and granuloperculatipollis rudis assemblage a fourth older assemblage is also informally defined a palynostratigraphic correlation between the nca the germanic basin and the dolomites has been obtained the four siliciclastic pulses recognized in the raibler schichten and lunz are also found in the dolomites and yield the same palynological associations the base of the schilfsandstein that record the carnian pluvial event in the germanic basin is correlated to the second or third siliciclastic pulse first or second shale of the raibler schichten siliciclastic pulses are thus correlated throughout western tethys and can thus be interpreted as short lived humid climate wiggles within the carnian pluvial event a quantitative analysis of the carnian successions of the nca highlights a shift toward hygrophytic elements in the uppermost julian and an abrupt return to xerophytic associations in the lower tuvalian the palynological hygrophytic associations that characterize the aulisporites astigmosus and lagenella martinii assemblages are present in many other parts of europe and middle east suggesting that the carnian pluvial event determined a humid climate perturbation in a wide area of the northern hemisphere spanning from tropical to high latitudes

a new classification of the turkish terranes and sutures and its implication for the paleotectonic history of the region abstract the turkish part of the tethyan realm is represented by a series of terranes juxtaposed through alpine convergent movements and separated by complex suture zones different terranes can be defined and characterized by their dominant geological background the pontides domain represents a segment of the former active margin of eurasia where back arc basins opened in the triassic and separated the sakarya terrane from neighbouring regions sakarya was re accreted to laurasia through the balkanic mid cretaceous orogenic event that also affected the rhodope and strandja zones the whole region from the balkans to the caucasus was then affected by a reversal of subduction and creation of a late cretaceous arc before collision with the anatolian domain in the eocene if the anatolian terrane underwent an evolution similar to sakarya during the late paleozoic and early triassic times both terranes had a diverging history during and after the eo cimmerian collision north of sakarya the kure back arc was closed during the jurassic whereas north of the anatolian domain the back arc type oceans did not close before the late cretaceous during the cretaceous both domains were affected by ophiolite obduction but in very different ways north directed diachronous middle to late cretaceous melange obduction on the jurassic sakarya passive margin senonian synchronous southward obduction on the triassic passive margin of anatolia from this it appears that the izmir ankara suture currently separating both terranes is composite and that the passive margin of sakarya is not the conjugate margin of anatolia to the south the cimmerian taurus domain together with the beydaglari domain part of the larger greater apulian terrane were detached from north gondwana in the permian during the opening of the neotethys east mediterranean basin the drifting cimmerian blocks entered into a soft collision with the anatolian and related terranes in the eo cimmerian orogenic phase late triassic thus suturing the paleotethys at that time the taurus plate developed foreland type basins filled with flysch molasse deposits that locally overstepped the lower plate taurus terrane and were deposited in the opening neotethys to the south these olistostromal deposits are characterized by pelagic carboniferous and permian material from the paleotethys suture zone found in the mersin melange the latter as well as the antalya and mamonia domains are represented by a series of exotic units now found south of the main taurus range part of the mersin exotic material was clearly derived from the former north anatolian passive margin huglu type series and re displaced during the paleogene this led us to propose a plate tectonic model where the anatolian ophiolitic front is linked up with the samail baer bassit obduction front found along the arabian margin the obduction front was indented by the anatolian promontory whose eastern end was partially subducted continued slab roll back of the neotethys allowed anatolian exotics to continue their course southwestward until their emplacement along the taurus southern margin mersin and up to the beydaglari promontory antaya mamonia in the latest cretaceous paleocene the supra subduction ocean opening at the back of the obduction front troodos type ocean was finally closed by eocene north south shortening between africa and eurasia this brought close to each other cretaceous ophiolites derived from the north of anatolia and those obducted on the arabian promontory the latter were sealed by a maastrichtian platform and locally never affected by alpine tectonism whereas those located on the eastern anatolian plate are strongly deformed and metamorphosed and affected by eocene arc magmatism these observations help to reconstruct the larger frame of the central tethyan realm geodynamic evolution

a new chronology for the end triassic mass extinction article i nfo the transition from the triassic to jurassic period initiating the age of the dinosaurs approximately 200 ma is marked by a profound mass extinction with more than 50 genus loss in both marine and continental realms this event closely coincides with a period of extensive volcanism in the central atlantic magmatic province camp associated with the initial break up of pangaea but a causal relationship is still debated the triassic jurassic t j boundary is recently proposed in the marine record at the first occurrence datum of jurassic ammonites post dating the extinction interval that concurs with two distinct perturbations in the carbon isotope record the continental record shows a major palynological turnover together with a prominent change in tetrapod taxa but a direct link to the marine events is still equivocal here we develop an accurate chronostratigraphic framework for the t j boundary interval and establish detailed trans atlantic and marine continental correlations by integrating astrochronology paleomagnetism basalt geochemistry and geobiology we show that the oldest camp basalts are diachronous by 20 kyr across the atlantic ocean and that these two volcanic pulses coincide with the end triassic extinction interval in the marine realm our results support the hypotheses of phanerozoic mass extinctions resulting from emplacement of large igneous provinces lips and provide crucial time constraints for numerical modelling of triassic jurassic climate change and global carbon cycle perturbations

the loppio oolitic limestone early jurassic southern alps a prograding oolitic body with high original porosity originated by a carbonate platform crisis and recovery abstract the loppio oolitic limestone is a lithostratigraphic unit of the early jurassic trento platform in the southern alps northern italy which deposited over an area of ca 3500 km 2 it appears as a roughly tabular or wedge shaped sedimentary body with thickness gradually increasing from 0 to ca 100 m toward the western platform margin we investigated the sedimentology petrography and bulk carbonate carbon isotope geochemistry of the loppio oolitic limestone in order to shed light on its depositional setting and origin the loppio oolitic limestone is made almost exclusively of oolitic grainstone and can be subdivided in two parts in the lower part ooids are poorly sorted and sedimentary structures are scarce or absent in the upper part sorting becomes good and sedimentary structures are common the vertical succession of sedimentary structures and the upward increase in sorting suggest a shallowing upward trend within the oolite a reddened surface meteoric cements and dinosaur footprints occur at the top of the unit testifying for a subaerial exposure which is also confirmed by carbon and oxygen stable isotopic data in terms of sequence stratigraphy the loppio oolitic limestone represents a highstand systems tract bounded at the top by a subaerial exposure surface bulk carbonate stable carbon isotope curves across the loppio oolitic limestone from 7 stratigraphic sections could be correlated over distances of tens of km on the whole trento platform this correlation suggests that the deposition of ooids was nearly synchronous across the platform a negative excursion of carbon isotopes with magnitude of ca 1 vpdb was identified within a lime mudstone unit nodular lithozone of the monte zugna formation immediately below the loppio oolitic limestone which can be correlated to a global perturbation of the carbon cycle in the mid sinemurian the flooding of a wide area of formerly peritidal carbonate platform below the wave base was interpreted as due to an ecological crisis that caused a drop of carbonate production we suggest that the subsequent recovery of carbonate production is marked by the shallowing upward succession of the loppio oolitic limestone which quickly occupied the accommodation space formed in consequence of the crisis thus preventing the platform drowning the loppio oolitic limestone deposited as an initially highly porous oolitic sand that was then topped by a clayey interval base of the rotzo formation giving origin to a structural and stratigraphic configuration that could be favourable for the accumulation of hydrocarbons in the subsurface the recurrence of similar facies superpositions formed in consequence of perturbations of the carbon cycle with documented climatic effects is discussed with regard to the tethysian record of mesozoic carbonate platforms

synchrony between early jurassic extinction oceanic anoxic event and the karoo ferrar flood basalt volcanism a well known second order mass extinction took place during the pliensbachian and toarcian stages of the early jurassic first recognized as a minor pliensbachian peak in the global extinction rate it has alternatively been interpreted as a regional response to the early toarcian oceanic anoxic event detailed studies established it as a global long term event spanning five successive ammonoid zones here we present a revised time scale based on highprecision u pb ages resolved to the zone level which suggests that elevated extinction rates were sustained for about 4 m y and peak extinction occurred at 183 ma recent isotopic dating of flood basalts from the southern gondwanan karoo and ferrar provinces documents a culmination in volcanic activity ca 183 ma the onset of volcanism is recorded as an inflection and start of a rapid rise of the seawater 87 sr 86 sr curve the synchrony of voluminous flood basalt eruptions and biotic crises as already noted for three of the major mass extinctions permits a causal relationship which in this case may be mediated by widespread oceanic anoxia

mapping mesoscale variability of the azores current using topex poseidon and ers 1 altimetry together with hydrographic and lagrangian measurements the semaphore mesoscale air sea experiment was conducted in the azores madeira region from july to november 1993 topex poseidon tip and ers 1 were flying simultaneously at that time the main purposes of this paper are to evaluate the estimation of the oceanic mesoscale circulation from the two different sets of altimetric data tip and ers 1 and to compare the results with in situ measurements provided by the semaphore hydrographic surveys and smface drifters three expendable bathytermograph conductivity temperature depth surveys in a 500 km2 box and a set of 47 lagrangian surface drifters drogued at 150m comparisons are carried out through the maps obtained by objective analysis ti om the four data sets the mapping accuracy of tip ers i tip and ers 1 combined and in situ data is investigated as weii as the sensitivity of the mapping to the correlation functions used there is a good qualitative agreement between altimetric maps and corresponding drifter and hydrographic maps for the three hydrographic surveys correlations are about 0 8 and the regression fit is about 0 6 0 7 the lower values are clue to the smooth climatology used to reference the altimetric maps the correlation for time differences is better with regression lines not significantly different from i especiaily when ers 1 and tip are combined tip mapping is almost as good as ers 1 mapping which was rather unexpected since the ers 1 space time sampling is better suited for the mesoscale this may reflect the fact that the signal mapped by the hydrography and drifters does not contain the high frequency wavenumber components tip and ers 1 combined provide better results although the improvement is not as large as expected probaply for the same reason

integrated stratigraphy and palaeoclimate history of the carnian pluvial event in the boreal realm new data from the upper triassic kapp toscana group in central spitsbergen norway the late triassic climate is characterized by arid conditions interrupted by a humid phase known as the carnian pluvial event cpe this wet phase is well documented in the tethyan realm but evidence from the boreal realm is scarce here we present evidence from quantitative palynology for the cpe from the kapp toscana group on central spitsbergen integrated with organic carbon isotope data linked to the geomagnetic polarity time scale our data reveal an early to mid julian 1 age for the tschermakfjellet formation the transition to the julian 2 is located in the de geerdalen formation and the isfjorden member is confirmed as mostly tuvalian 3 in age the aulisporites astigmosus pollen assemblage zone that marks the base of the cpe in the tethys realm at the base of the julian 2 is assigned to the julian 1 in the boreal region palaeoclimate proxy data inferred from principal component analysis indicate wetter conditions from the julian 2 onwards which is in agreement with the establishment of local swamp vegetation on top of a delta plain the palaeotemperature curve indicates a period of cooler climate during the early julian 1 followed by warming during the late julian 1 supplementary materials a list of all identified morphotaxa of pollen spores and aquatic palynomorphs is available at http www geolsoc org uk sup18879

cause of upper triassic climate crisis revealed by re os geochemistry of boreal black shales abstract the triassic period is bracketed by two of the big five phanerozoic mass extinctions though long viewed as a period of climatic stability emerging data suggest multiple climatic swings and at least one severe ecological crisis linking these climatic instabilities with probable causes is hampered by poor age control within the triassic time scale here we present new re os ages for shale sections straddling middle upper triassic stage boundaries nominal re os isochron ages of 236 6 and 239 3 ma for the top and base of the ladinian upper middle triassic bring absolute time into the contentious triassic time scale and place the beginning of the late triassic about 12 m y earlier than previously assigned a marked decrease in initial 187os 188os in upper ladinian shale records input from wrangellian flood basalts an instigator in the carnian late triassic pluvial event and accompanying radiation of key fossil groups e g dinosaurs and calcareous nanoplankton an absolute time scale is proposed for the anisian ladinian carnian boundaries based on re os geochronology

climate of the late devonian to triassic abstract remarkable changes are apparent in climate during late devonian triassic times mostly the climate was rather different from the present the faunas and floras offer much evidence for understanding the climate but in turn understanding the palaeogeography of the faunas and floras is dependent on understanding the climate and the changes in climate the late devonian apparently had a warm climate the climate of the early carboniferous was warm and equable no cold climate can be identified and apparently no ice was present at the poles even a cold temperate climate is difficult to identify on the other hand the tropical zone does not appear to have been particularly hot apparently this reflects an ocean current system and a weather system different from the present ones during the late carboniferous the world became colder and the faunas and floras more provincial ice probably mountain ice appeared in boreal and austral regions widespread glaciation occurred in the earliest permian but it had a very assymetrical character whether continental ice sheets like those of the pleistocene were present is not proven during the early permian the world became warmer probably with some fluctuation in climate and with evidence for seasonal ice but not for glaciers during the late permian the warming continued and a new kind of provincialism developed within the broad tropical and subtropical zone by the end of the permian the earth was very warm in the early triassic no equatorial humid zone can be identified and whereas the tropical zone was hotter than at present the polar zones were also warm the early triassic appears to have been almost universally dry the climate remained warm during the middle and late triassic but humid zones can be recognized the climate also showed some apparent assymetry the pecularities of the climate and the change of climate in this interval of time are not readily explainable either on the basis of the present climate or the present or a similar distribution of land and sea nor are they readily explainable on reconstructions commonly accepted such as pangaea formed in the carboniferous as is often claimed probably more basic data are required before any satisfactory explanations are possible and as well as terrestrial effects including a change in the angle of the earth s rotation extra terrestrial planetary and galactic effects require study

synchroneity of climatic change and extinctions in the late triassic although the late triassic was a time of widespread aridity evidence exists for a significant increase in rainfall during the middle to late carnian upper triassic playa lake sediments were interrupted by late carnian fluviatile sandstones with erosive bases and high kao linite illite ratios there was also an increase in the clastic component of marine sequences during this interval middle and upper carnian marine carbonates show an extreme depletion in 13 c values consistent with increased fresh water influx large scale karstic phenomena in limestone areas subaerially exposed during the late triassic are a further indication of increased rainfall important faunal and floral changes occurred during the carnian norian interval marine invertebrate turnover was greatest at the lower middle carnian boundary and terrestrial extinctions were concentrated at the carnian norian boundary the cause of this carnian pluvial episode may have been related to the rifting of pangea through disruption of atmospheric and oceanic circulation patterns eustatic changes or the effects of volcanism associated with rifting a change in surface ocean temperature salinity or ph or habitat loss may have caused the decline of many shallow marine invertebrates at the start of the middle carnian a return to arid conditions at the carnian norian boundary would account for the turnover among terrestrial vertebrates and plants

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

properties of rossby waves in the north atlantic estimated from satellite data this study uses satellite observations of sea surface height ssh to detect westward propagating anomalies presumably baroclinic rossby waves in the north atlantic and to estimate their period wavelength amplitude and phase speed detection involved a nonlinear fit of the theoretical dispersion relation for rossby waves to the time longitude spectrum at a given latitude estimates of period wavelength and phase speed resulted directly from the detection process based on these a filter was designed and applied to extract the rossby wave signal from the data this allowed a mapping of the spatial variability of the rossby wave amplitude for the north atlantic results showed the familiar larger speed of observed rossby waves relative to that expected from theory with the largest differences occurring at shorter periods the data also show that the dominant rossby waves those with periods that are less than annual propagated with almost uniform speed in the western part of the north atlantic between 308 and 408n in agreement with previous studies the amplitude of the rossby wave field was higher in the western part of the north atlantic than in the eastern part this is often attributed to the influence of the mid atlantic ridge by contrast this study through an analysis of the wave spatial structure suggests that the source of the baroclinic rossby waves at midlatitudes in the western north atlantic is located southeast of the grand banks where the gulf stream and the deep western boundary current interact with the newfoundland ridge the spatial structure of the waves in the eastern north atlantic is consistent with the formation of these waves along the basin s eastern boundary

observations on the long period variability of the gulf stream downstream of cape hatteras to examine the long period variability of the gulf stream sea level residuals relative to a 2 year mean sea level in the gulf stream downstream of cape hatteras between 75 w and 60 w longitude are used residuals as derived from geosat altimetry between november 1986 and december 1988 were gridded in space and time at a temporal resolution of 10 days and spatial resolution of 1 4 complex empirical orthogonal function ceof analysis was applied to the data set to extract the spatially correlated signal with the original data sub sampled to 1 2 in addition to determining the space time scales and propagation characteristics of the different modes wavenumber frequency spectral techniques were used to separate the variability into propagating and stationary components the ceof technique applied to the data set indicated that the first four ceof modes accounted for 60 of the variability and were found to be above the noise level 99 of the time ceof 1 was associated with westward propagation at 5 km d at a wavelength of 2000 km and eastward propagation at 1 2 km d centered at a 500 km wavelength this first ceof is in good agreement with thin jet equivalent barotropic models which predict westward propagation for wavelengths greater than 1130 km a deflection of the wavelike pattern at 65 w also indicates a possible topographic effect a simple scaling of the effect of topography indicates that for length scales longer than the internal rossby radius of deformation the topographic term is at least of the same order of magnitude as the beta effect the second ceof was more broadbanded in wavenumber space with eastward propagation occurring in a wavenumber frequency band between 300 and 1400 km and 0 5 and 2 0 cycles yr the third ceof is similar in structure to the first but with less energy ceof 4 was clearly identifiable with higher frequencies than the first three with westward propagation at 4 km d the spatial location of this mode along with the westward propagation indicates possible influences from eddy stream interactions thus topography rossby wave dynamics and eddy stream interactions all appear to have a significant role in determining the space time scales and propagation properties of the long period response of sea level in the gulf stream

generation and propagation of annual rossby waves in the north atlantic abstract results of a nonlinear quasi geostrophic mode model on the plane with topography and coastal geometry of the north atlantic in the area 10 50 n 10 80 w are presented two modes are used in this study the baroclinic one is based on the mean density profile from the levitus dated at 30 n mean and annual variations of the wind stress curl which drive the model were obtained from the bunker climatic atlas annual rossby waves emanating off the eastern coast are strongly influenced by the mid atlantic ridge west of the mar a relative minimum of energy is observed the waves are influenced and modified by variable bottom topography in the western basin two regions are identified where rossby waves are generated the gulf stream and its extension towards the east and the southern flank of the subtropical gyre compared to the north pacific annual rossby waves seem to be less energetic in the north atlantic

a model study of the spectral structure of boundary driven rossby waves and related altimetric implications abstract a two layer primitive equation box model of the north pacific ocean is used to highlight and analyze some general aspects of the linear large scale boundary driven oceanic variability that are detectable through altimeter observations the model is forced by a white noise wind and a spectral analysis of the zonal and meridional barotropic and baroclinic velocity components is carried out several dynamical features are identified in terms of boundary driven rossby waves and their spatial structure and frequency dependence are examined theoretically and discussed in connection with recent studies based on altimeter data in particular the following aspects of the variability are analyzed 1 beta refracted baroclinic rossby waves which are found to be generated along the eastern boundary of the ocean by the passage of coastal kelvin waves originating from the equatorial waveguide and 2 westward intensified barotropic rossby waves which originate from the western boundary of the ocean after

the changing climate framework and depositional dynamics of triassic carbonate platforms from the dolomites abstract the triassic of the dolomites offers a valuable opportunity to investigate the relationships between climate fluctuations and the changing depositional dynamics of carbonate platforms the reconstruction of the large palaeoclimatic modification is based on the synthesis of multiple sedimentological palaeobotanical pedological and geochemical proxies the triassic climate fluctuations were generally fast in nature and were probably associated with a latitudinal shift of the monsoon belts during the triassic the dolomites were placed at an intertropical northern latitude of about 16 18 and were generally dominated by dry climate and elevated temperature at least five pulses toward moister climate are however documented dated to early olenekian middle anisian late ladinian middle carnian and late norian times within this variable climatic scenario the carbonate systems record a global evolutionary trend from late permian early triassic regional shelves rich in loose micrites and bio calcarenites to anisian ladinian synsedimentary cemented steep sided 35 40 high relief platforms and back to carnian low angle ramps moist transgressive episodes were surprisingly prone to the spreading of corals and other colonial reef organisms probably because of the reduced space competition by syndepositional cementation structures the permo triassic boundary extinction dramatically impacted on the calcified organism communities but the carbonate depositional architecture nevertheless stayed almost unaffected through the boundary the early triassic and earliest anisian were commonly associated with hyperhaline sometimes evaporitic conditions intervals of moister climate and efficient river discharge are however documented by earliest induan and early olenekian sediments the latter terrigenous deposits matched a crisis in the carbonate production after a return to arid conditions during the anisian a fluctuation toward moister climate developed associated to a massive continental vegetation cover the anisian tectonic activation of the region fragmented the previous carbonate shelf triggering the development of three generations of fast prograding but globally backstepping isolated platforms recording an increasing role of the synsedimentary cementation a dry climate dominated the late anisian and early ladinian interval at the time a fast subsidence pulse was associated with platform drowning and basinal anoxia only a few aggrading pinnacles were able to survive providing the nuclei for larger prograding platforms during a dry climate interval massive syndepositional cementation generated a major source of carbonate carbonate production stayed active through the ladinian magmatic phase but the onset of volcanism was associated with a large modification in the platform carbonate facies which became dominated by automicrites moist climate phases are well documented again during the late ladinian followed by a return to dry conditions the late ladinian early carnian platforms prograded toward the eastern dolomites depocentre eventually infilling almost the whole of the accommodation space the middle portion of the carnian recorded renewed sharply moist phases associated with the demise of the rimmed platforms and with the return to loose sediment ramps at least four separated humid fluctuations can be identified in this carnian interval alone climate then returned to persistent aridity until the late norian moist phase

long baroclinic rossby waves detected by topex poseidon residual sea surface height anomaly fields are obtained over the north atlantic basin from topex poseidon altimeter data evidence of westward propagating anomalies characterized as first mode baroclinic rossby waves is presented the phase speeds are obtained from the analysis of the autocorrelation matrices of the residual surface height anomaly in three dimensions on a 5 5 grid periods are calculated by least squares fitting a sinusoidal function to the time series at each grid point zonal and meridional wavelengths are obtained from the phase speed and period and are least squares fit to the data as a consistency check zonally averaged westward phase speeds vary between 1 and 27 km d between 50 and 5 n increasing southward phase speeds are directed to the southwest north of approximately 25 n and to the northwest south of this latitude the sea surface height signal is divided into two spectral bands the first with periods between 280 and 450 days and the second with periods between 120 and 280 days for the first band the average of the periods taken over the whole basin is 370 days in the second band a signal of period between 6 and 7 months is evident also throughout the basin the zonally averaged zonal wavelengths associated with the first band are in the range of 400 4600 km between 50 and 5 n and for the second band are in the range 270 2500 km between 45 and 5 n longer wavelengths are found close to the southern boundaries shorter wavelengths are found in the northern portion of the basin comparison with results from numerical models suggests that the baroclinic waves observed at midlatitudes are generated at the eastern boundary by fluctuations of the wind stress curl waves observed south of 20 n support the hypothesis of direct wind forcing

high precision geochronology links the ferrar large igneous province with early jurassic ocean anoxia and biotic crisis abstract apparent synchrony between eruption emplacement of large igneous province lip magmas and mass extinction has led to the implication of magmatism as a primary trigger of global scale environmental change evaluating the efficacy of magmatism as a driver of global change depends on the relative timing of magmatism and environmental change and the magma effusion intrusion rate both of which can be constrained by high precision geochronology early jurassic pliensbachian toarcian global ocean anoxia and acidification carbon isotope perturbations and biotic crisis have been linked to synchronous eruption and emplacement of the karoo and ferrar lips to better constrain the timing and duration of ferrar magmatism we apply the single crystal chemical abrasion u pb id tims method to zircon crystals isolated from twenty ferrar lip sills and lavas and the dufek intrusion dates suggest that both intrusive and extrusive ferrar magmatism occurred over an interval of 349 49 kyr beginning with intrusive magmatism as early as 182 779 0 033 ma lava eruption was synchronous with and in some cases postdates intrusion when coupled with existing geochronology on the karoo province our dates confirm broad synchrony between karoo and ferrar magmatism though karoo magmatism began demonstrably prior to ferrar magmatism starting as early as 183 246 0 045 ma the short lived magmatic history of the ferrar lip makes it a plausible trigger for early jurassic environmental change

ichnological evidence of semi aquatic locomotion in early turtles from eastern iberia during the carnian humid episode late triassic abstract some of the earliest european records of fossil turtle footprints late triassic middle carnian 227 237 ma are interpreted from 46 footprints from three outcrops domeno quesa and cortes de pallas located in the iberian range eastern spain the samples were obtained from upper triassic rocks in keuper facies they are characterized in the studied area by two well defined evaporitic sequences separated by a detrital stratigraphic interval constituting the manuel sandstones formation in which the studied fossil footprints were recorded these fluvial deposits are correlatable with the carnian humid episode the footprints are tridactyl and tetradactyl mainly digitigrade and elongated scratch marks are common the digit traces present triangular and curved claws the morphology of these marks suggests they were produced by the autopodium of a tetrapod animal while swimming near the bottom and they are consistent with the anatomical features of a turtle s manus other footprints were produced by turtles walking in wet medium to coarse grained sand in a subaerial environment a short trackway is identified sharing similarities with both the ichnogenera emydhipus and chelonipu s the observed tracks support a freshwater semi aquatic habit for some stem turtles during the early late triassic these are remarkably ancient turtle tracks close to the origin of the group as indicated by skeletal fossils they confirm that the earliest forms were narrowly related to aquatic fluvial environments

a carbon isotope perturbation at the pliensbachian toarcian boundary evidence from the lias group ne england a perturbation in the carbon isotope record at the time of the pliensbachian toarcian boundary 184 ma in the early jurassic is reported based on new data from yorkshire england two sharp 13 c org negative excursions each with a magnitude of 2 5 and reaching minimum values of 28 5 are recorded in the bulk organic matter record in sediments of latest pliensbachian to earliest toarcian age a similar pattern of negative carbon isotope excursions has been observed at the stage boundary in the sw european section at peniche portugal in 13 c carbonate 13 c wood and 13 c brachiopod records the isotopic excursion is of interest when considering the genesis and development of the later toarcian oceanic anoxic event oae as well as the second order global extinction event that spans the stage boundary furthermore the isotope excursion potentially provides a chemostratigraphic marker for recognition of the stage boundary which is currently achieved on the basis of different ammonite faunas in the nw european and tethyan realms

a continental record of the carnian pluvial episode cpe from the mercia mudstone group uk palynology and climatic implications the generally arid late triassic climate was interrupted by a wet phase during the mid carnian termed the carnian pluvial episode cpe quantitative palynological data from the mercia mudstone group in the wessex basin uk reveal vegetation changes and palaeoclimate trends palynostratigraphy and bulk organic carbon isotope data allow correlation to other carnian successions the palynostratigraphy indicates that the dunscombe mudstone is julian and the lowest part of the overlying branscombe mudstone formation is tuvalian the aulisporites acme characterizing the cpe in tethyan successions and the germanic basin is missing in the uk the quantitative palynological record suggests the predominance of xerophyte floral elements with a few horizons of increased hygrophytes a humidity signal is not seen owing to the dry climate in central pangea also the signal might be masked by the overrepresentation of xerophyte regional pollen and the predominance of xerophyte hinterland flora the bias towards regional pollen rain is enhanced by the potential increase in continental runoff related to seasonally humid conditions and differences in pollen production rates and transport mechanisms the vegetation of british cpe successions suggests a more complex climate history during the carnian indicating that the cpe is not recognized by the same changes everywhere supplementary material a detailed lithological log of the strangman9s cove devon outcrop with the description of the mercia mudstone group lithostratigraphical units a description of the laboratory techniques seven photoplates with selected spores and pollen grains a list of all identified palynomorphs excel sheets with the palynological and palynofacies counts bulk organic carbon isotope ratios and total organic carbon values of the strangman9s cove outcrop are available at https doi org 10 6084 m9 figshare c 4138085

climatic and biotic change in the late triassic generally arid conditions that pervaded much of europe and north america during the late triassic were interrupted by a wet monsoonal climatic phase during middle and late carnian times extensive fluviatile sandstones deposited at this time throughout the region occur within a thick sequence of playa lake mudstones the sandstones occasionally contain kaolinite suggesting a humid climate an extreme 13 c depletion in a shallow marine sequence of this age in israel has been interpreted as evidence for an influx of freshwater a widespread change from carbonates to clastics in marine sequences at this time may also be climate related water course cave systems in limestone areas exposed during the late triassic indicate high levels of runoff during the middle and late carnian the marine invertebrate fauna shows a significant turnover at the end of the early carnian the terrestrial fauna and flora were relatively unaffected at this time but subsequently diversified prior to a major biotic turnover at the carnian norian boundary these periods of biotic change appear to be synchronous with the onset and cessation of a carnian humid phase the change to a monsoonal climate during this interval has been documented over more than 90 of longitude between 5 and 50 north of the triassic equator it may have been caused by rising atmospheric co 2 levels due to volcanism associated with the incipient dispersal of pangaea

palynology of the circum mediterranean triassic phytogeographical and palaeoclimatological implications following a tentative evaluation of palynological information from ladinian and more particularly karnian successions there seems to be every indication that qualitative and quantitative compositional differences of palynological assemblages could well be applied in testing concepts of triassic phytogeography and palaeoclimatology

global carbon cycle perturbations triggered by volatile volcanism and ecosystem responses during the carnian pluvial episode late triassic abstract the carnian pluvial episode cpe was a dramatic climatic event during the early late triassic the cpe has been recognized worldwide and is marked by the termination of carbonate platform successions and by pronounced negative 13c excursions denoted as the cpe excursion the onset of the cpe has been proposed to be linked with the volatile eruption of the wrangellia large igneous province w lip however this extreme climatic event remains disputed in terms of its precise global correlation timing of onset duration and global magnitude we compiled a database of 13 conodont biozone controlled stable isotope reference sections throughout the tethyan region after a reexamination of previously published conodont taxonomy from each section the statistics on the conodont assemblages zones yield a global set of 17 high resolution conodont unitary association zones uazs spanning the entire carnian successions a set of age tie points placed an age model on this global uaz scale we added paired 13ccarb and 13corg data from two sections in south china to other records in this global database and then normalized all carbon isotope datasets a pronounced negative 13ccarb excursion with a magnitude of 2 0 5 from an average of 3 to 1 is evident in these normalized trends and is recognized around the entire tethys realm the cpe excursion coincides with conodont uaz 4 234 ma through uaz 8 within the mazzaella carnica and paragondolella praelindae zones julian2 and has a duration of ca 1 5 myr we note that an apparent delayed onset of the cpe excursion in south china relative to elsewhere in the tethys as suggested by previous studies may have been an artifact caused by incomplete conodont stratigraphic records and or irregularities in taxonomic identification a carbon and phosphorus cycle model highlight the strong relationship between the eruption of the w lip and cpe excursion however the estimated amount of co2volatiles released by the w lip would directly account for only 25 of the total amount of light carbon required to explain the combined magnitude and duration of the global cpe excursion

stetson pit dare county north carolina an integrated chronologic faunal and floral record of subsurface coastal quaternary sediments continuous split spoon samples from a drill hole penetrating 34 m of coastal plain sediments at stetson pit in dare county north carolina were taken for lithologic aminostratigraphic faunal ostracodes and floral pollen analyses three distinct aminozones are recognized in the subsurface section based upon d alloisoleucine l isoleucine a i values in each of the molluscan species mulinia lateralis and mercenaria sp ostracode zonations in the subsurface section are based on percentages of 80 thermophilic and cryophilic species those living today south and north of cape hatteras and the percentages of brackish water species five assemblage zones are delineated six pollen assemblage zones are also delineated within the subsurface section based upon study of 48 sediment samples the subsurface record at stetson pit is interpreted to represent portions of four interglacials based upon the combined faunal floral and aminostratigraphic data the two younger aminozones with amino acid age estimates of 100 000 20 000 yr 7 2 to 11 2 m msl and 300 000 500 000 yr 13 to 14 2 m msl represent portions of middle late pleistocene interglacials the lower aminozone 17 4 to 33 m msl spans an interval that probably includes at least two interglacials based upon faunal and floral records and has an age estimated to be between 800 000 and 1 300 000 yr boundaries delineated by faunal floral and amino acid methods do not always coincide due to sampling constraints and phase lags between the different records one major unconformity at 17 4 m msl in the stetson pit section is easily recognized from lithologic characteristics and may represent a hiatus of as much as 800 000 yr lithologic changes associated with all other zone boundaries are subtle and would probably not be considered significant in the absence of faunal floral or amino acid data

a tethys wide mid carnian upper triassic carbonate productivity crisis evidence for the alpine reingraben event from spiti indian himalaya abstract a significant mid carnian lithological change from carbonatic to siliciclastic sedimentation is described from the spiti himalaya n india the recorded sudden increase of terrigenous influx occurs at the boundary from the chomule to the rama formation it is dated within the late lower carnian uppermost aonoides zone and isochronous all over the tethys himalaya bio and chemostratigraphic data point to a synchrony with changes in carbonate productivity known from on area of wide extent along the nw tethys the reingraben event of the northern calcareous alps austria defines a regional decline in carbonate productivity related to both a platform demise and enhanced siliciclastic input laminated shales found in a distal part of the spiti basin document the onset of anoxic conditions within the deeper shelf synchronous to the reingraben event in austria high resolution biostratigraphy and identical 13ccarb curves are therefore in support of a direct link between the change in spiti and the reingraben event our data combined with a comprehensive review of previously postulated scenarios regarding the reingraben event suggest linking of climatic change with siliciclastic input and a carbonate productivity crisis initiated by onset of a relatively humid megamonsoonal late lower carnian atmospheric system that affected both the southern and northwestern tethys and point to a supra regional trigger of the alpine reingraben event

carbon isotope stratigraphy and palynostratigraphy of the triassic jurassic transition in the tiefengraben section northern calcareous alps austria abstract the end triassic is characterized by enhanced rates of biotic turnover in both the marine and terrestrial realms carbon isotope anomalies have been reported worldwide that may indicate coeval global disturbances in the biogeochemical cycles here we present the results of an integrated study of the palynomorph assemblages and the carbon isotope composition of organic matter in the tiefengraben section near st wolfgang austria carbon isotope values from bulk organic matter show significant fluctuations through the triassic jurassic t j boundary interval with two prominent negative 13 c org excursions an initial negative carbon isotope excursion occurs at the base of the kendlbach formation tiefengraben member pre planorbis beds although triassic ammonoids and conodonts have their highest occurrence at the top of the underlying kossen formation the palynomorph and calcareous microfossil assemblages indicate still a rhaetian age for the lower part of the tiefengraben member high abundance of prasinophytes during the interval of the initial carbon isotope excursion may represent a bloom of green algae that flourished as a result of the disturbance of the marine ecosystems increased spore abundance together with the disappearance of distinctive late triassic pollen types e g ovalipollis rhaetipollis indicate vegetation changes on land that are contemporaneous with the marine biotic crisis a second negative carbon isotope excursion occurs in the middle part of the tiefengraben member based on palynological evidence the t j boundary may be drawn at about this level by the lowest occurrence of cerebropollenites thiergartii the established carbon isotope curve as well as palynostratigraphic and other biostratigraphic events can be correlated with st audrie s bay england

tracking an upper limit of the carnian crisis and or carnian stage in the western carpathians slovakia the late triassic timescale especially the carnian norian boundary is poorly constrained mainly due to a paucity of high precision radio isotopic ages that can be related accurately to contradictions between the biostratigraphic and magnetostratigraphic correlations la icp ms dating of detrital zircons from five samples of the lunz formation the upper triassic siliciclastic sediments from the western carpathians slovakia provided a wide spectrum of ages that vary from late archaean ca 2582 ma to triassic ca 216 ma these marine delta sediments represent a typical product of the carnian crisis a major climate change and biotic turnover that occurred during the carnian stage in the tethys ocean within the carbonate shelf and intrashelf basins in the northern calcareous alps and the western carpathians the supply of clastic material in the studied lunz formation was derived from several sources especially i from the recycled variscan orogen ii from the remote east european platform and iii from the contemporaneous triassic volcanic sources syn sedimentary volcanic zircons with a concordia age of 221 2 1 6 ma calculated from 12 single analyses represent the maximum age of deposition of the lunz formation and demonstrate that the upper limit of the carnian crisis and or the carnian stage in the alpine carpathians realm is younger than the current age of the carnian norian boundary at ca 227 ma listed on the international chronostratigraphic chart international commission on stratigraphy 2016 12 edition

a review of mesozoic climates there is overwhelming evidence based on the distribution of distinctive sediments and fossils and oxygen isotope data that the climate of the mesozoic world was appreciably more equable than that of today with no polar ice caps but precise quantitative data are not available except for an episode of late cretaceous cooling there is no good documentation of any significant change in global temperature distributions through the era the distribution of coals and evaporites together with other criteria indicates a pattern of humid arid and zones appreciably different in important respects from that of today during the triassic and jurassic western pangaea in low to middle latitudes was largely arid but in the early cretaceous the lands on the margin of the newly opening central atlantic and western tethys experienced a humid climate by late cretaceous times arid zones had become very restricted in extent because of insufficient suitable data attempts at climatic modelling have had only modest success and only to a limited extent can the major long term changes in climate between the permian and the present be explained in terms of changing geography the most probable explanation of mesozoic equability is an increased atmospheric co 2 content a number of enigmas remain such as the existence of flourishing forests in polar palaeolatitudes whereas for the late cenozoic short term climatic changes can be related successfully to variations in the geometry and mechanics of the earth sun system there is a long way to go before comparable success can be claimed for the mesozoic

perturbations in the carbon cycle during the carnian humid episode carbonate carbon isotope records from southwestern china and northern oman the carnian humid episode is an interval of prominent climatic changes in the late triassic we studied the carbon isotope 13c geochemistry of carbonates from sections in southwestern china and northern oman 13c records from the yongyue section western guizhou south china show a progressive positive shift from 1 4 to 2 8 in the early to middle julian 1 substage this positive trend is followed by a swift negative shift of c 4 2 from 2 8 to 1 4 in the julian 2 substage 13c from the wadi mayhah section northern oman shows a positive shift from 2 2 to 2 8 in the julian 1 substage followed by a negative shift of c 3 2 from 2 8 to 0 3 in the julian 2 substage the 13c records from the two study sections generally correlate well with each other as well as with published records pointing to a considerable input of isotopically light carbon starting in the late julian 1 substage such a large amount of light carbon probably derived from direct degassing and the sediment sill contact metamorphism of the panthalassan wrangellia large igneous province and contemporary tethyan volcanism the voluminous volcanogenic greenhouse gases probably contributed to the warming pulse in the middle carnian thus the dry wet climatic transition during the carnian humid episode is best interpreted as a warm climate driven intensification of the activities of the atmospheric circulation and hydrological cycle