a microearthquake study of the mygdonian graben northern greece during march and april 1984 a temporary network of 29 portable stations was operated in the region of the mygdonian graben near thessaloniki northern greece where a destructive earthquake ms 6 5 had occurred in the summer of 1978 during a period of six weeks we recorded 540 earthquakes with magnitudes ranging from 0 2 to 3 0 from this set of data 254 events are selected which according to us have a precision in epicenter and depth better than 1 5 km a total of 54 single event focal mechanisms have been determined the seismicity and focal mechanisms show a rather complex pattern there are no clear individual faults but the e w and nw se striking zones show n s extension zones striking nne ssw show dextral strike slip motion but nw se zones with sinistral strike slip are also observed in the center of the graben where the 1978 earthquake was located we observe several thrust mechanisms distributed in two groups showing either nw se or e w compression these earthquakes seem to be located 2 km above the earthquakes showing normal mechanisms the mean direction of the t axes found from the focal mechanisms trends n15 and dips sub horizontal we propose a model for the formation and evolution of a complex graben system comprising several stages in the initial stage the deformation occurs along pre existing nw se or nne ssw faults with normal or strike slip movements in the second stage a new e w trending group of normal faults is formed over the ancient fault network these new faults have a direction perpendicular to the mean t axis and accommodate better the actual state of stress at this stage the initial faults adjust to the deformation produced by the e w trending new faults and may constitute geometric barriers to the evolution of the new normal faults

the lilliput effect in the aftermath of the end permian extinction event early triassic animal body fossils and trace fossils are small relative to those in older and younger intervals size decreases sharply through the end permian extinction event and permian triassic boundary and the smallest sizes are encountered in the parvus and isarcica zones of the earliest induan animals appearing within these two zones are also exceedingly small compared to younger congenerics and conspecifics temporary dramatic size decrease of surviving taxa in the immediate aftermath of the extinction event is an example of the lilliput effect coined by urbanek a 1993 biotic crises in the history of upper silurian graptoloids a palaeobiological model historical biology 7 29 50 body size increases somewhat from the carinata zone mid induan but remains depressed for the duration of the early triassic and pre extinction sizes are not commonly recorded until at least the middle triassic marine and terrestrial faunas appear to be similarly affected the lilliput effect and longer term size reduction could be the result of several factors environmental parameters such as marine anoxia due to low atmospheric concentrations of oxygen at this time coupled with sluggish ocean circulation in a greenhouse world and food shortage are the likely proximal causes for the early triassic lilliput effect no single cause can explain all the observations and a combination of factors are likely to be involved

timing of recovery from the end permian extinction geochronologic and biostratigraphic constraints from south china four volcanic ash beds bracket the early middle triassic boundary as defined by conodont biostratigraphy in a stratigraphic section in south china high precision u pb dates of single zircons allow us to place the early to middle triassic olenekian anisian boundary at 247 2 ma magnetic reversal stratigraphy allows global correlation the new dates constrain the early triassic interval characterized by delayed biotic recovery and carbon cycle instability to 5 m y this time constraint must be considered in any model for the end permian extinction and subsequent recovery

aftershocks of the june 20 1978 greece earthquake a multimode faulting sequence abstract a 10 station portable seismograph network was deployed in northern greece to study aftershocks of the magnitude m b 6 4 earthquake of june 20 1978 the main shock occurred in a graben about 25 km northeast of the city of thessaloniki and caused an east west zone of surface rupturing 14 km long that splayed to 7 km wide at the west end the hypocenters for 116 aftershocks in the magnitude range from 2 5 to 4 5 were determined the epicenters for these events cover an area 30 km east west by 18 km north south and focal depths ranges from 4 to 12 km most of the aftershocks in the east half of the aftershock zone are north of the surface rupture and north of the graben those in the west half are located within the boundaries of the graben composite focalmechanism solutions for selected aftershocks indicate reactivation of geologically mapped normal faults in the area also strike slip and dip slip faults that splay off the western end of the zone of surface ruptures may have been activated the epicenters for four large m 4 8 foreshocks and the main shock were relocated using the method of joint epicenter determination collectively those five epicenters form an arcuate pattern convex southward that is north of and 5 km distant from the surface rupturing the 5 km separation along with a focal depth of 8 km average aftershock depth or 16 km neis main shock depth implies that the fault plane dips northward 58 or 73 respectively a preferred nodal plane dip of 36 was determined by b c papazachos and his colleagues in 1979 from a focal mechanism solution for the main shock if this dip is valid for the causal fault and that fault projects to the zone of surface rupturing a decrease of dip with depth is required

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

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

the environmental seismic intensity scale esi 2007 in greece addition of new events and its relationship with magnitude in greece and the mediterranean preliminary attenuation relationships abstract the environmental seismic intensity esi scale has been officially released in 2007 and is based on the quantification of earthquake environmental effects due to its quantitative nature the scale improves the process of assessing macroseismic intensities particularly in the epicentral area of those cases in which sole traditional intensity scales prove to be ineffective following a large number of publications that applied this relatively newly established scale there is some need for parametrization this is because this intensity scale can offer new insights to seismic hazard assessment and has the potential to reduce the uncertainties that stem from traditional macroseismic scales this study has three main goals firstly to enrich and compile an esi 2007 database from earthquakes in greece by adding 4 new events secondly to extract a relationship between magnitude and the esi 2007 for greece and the mediterranean thirdly to offer a preliminary estimate of how the intensity attenuates with distance after developing a code in python language to assist this process the esi 2007 scale was applied in the 1995 ms 6 6 kozani grevena earthquake the 1978 mw 6 5 thessaloniki earthquake the historic 1894 atalanti earthquake sequence m 6 4 and m 6 8 and the 365ad event in crete m 8 4 these events were selected because they have well documented and extensive co seismic effects including primary and secondary surface ruptures rockfalls landslides and liquefaction phenomena for the kozani earthquake extracted results were correlated with sar interferograms in order to provide a complete and high spatial resolution of the ground deformation both the kozani grevena and the thessaloniki events produced a maximum intensity ix on the esi 2007 scale the atalanti earthquake produced a maximum intensity x and the 365ad crete earthquake a maximum intensity xii overall the esi 2007 scale compares fairly well with the traditional macroseismic scales except for some villages in the kozani grevena epicentral area where due to the poor quality of buildings existing scales overestimated the intensity by one degree compared to the esi 2007 it is interesting to note that both for greece and the mediterranean area a strong correlation exists between mw and the esi 2007 scale in particular the following relationships between the mw and the esi scale have been extracted i for greece io esi 2007 3 1427 exp 0 1643mw and ii for the mediterranean io esi 2007 3 3543exp 0 1557mw however more events and more data regarding the intensity distributions are required to establish the intensity attenuation with distance

early triassic conodonts and carbonate carbon isotope record of the idrija žiri area slovenia the first recovery of the conodont hindeodus parvus from iri slovenia a few years ago highlights this area for early triassic biostratigraphical study systematic sampling of five sections in the idrija iri area has yielded the new species platyvillosus corniger sp nov and neospathodus planus sp nov based on these new species and other conodont elements collected here nine discrete conodont unitary association ua zones are proposed for this area in ascending order they are eurygnathodus costatus zone ua 1 eurygnathodus hamadai zone ua 2 foliella gardenae zone ua 3 neospathodus robustus zone ua 4 platyvillosus corniger zone ua 5 platyvillosus regularis zone ua 6 triassospathodus hungaricus zone ua 7 triassospathodus symmetricus zone ua 8 and neospathodus robustispinus zone ua 9 the conodont and 13c data indicate that these conodonts span the dienerian smithian i e induan olenekian boundary interval to the spathian and they also indicate that triassospathodus hungaricus zone ua 7 does not occur at the base of the spathian these conodont zones are valuable for stratigraphic correlation within central and southern europe and they also promote a better correlation worldwide conodonts in the idrija iri area were adapted to a shallow water environment in an epeiric ramp

size variation of conodonts during the smithian spathian early triassic global warming event the early triassic smithian spathian boundary ssb crisis coincided with an episode of extreme warmth a high resolution stratigraphic framework comprising six conodont zones is provided in the jiarong section nanpanjiang basin in south china detailed size measurements of 441 conodont elements of the closely related genera neospathodus triassospathodus and novispathodus show for the first time that this clade suffered a temporary but significant size reduction during the ssb crisis the size reduction of conodonts was probably caused by an episode of global warming

travel times of pn waves in the aegean and surrounding area summary based on accurately located 23 very shallow earthquakes h 1 14 km in northern and central greece by portable networks of seismic stations and by the joint epicentre method the travel times of the p waves from the foci of these earthquakes to the sites of 54 permanent stations in the balkan region have been determined the travel times of p waves in the central and eastern part of the area eastern greece south eastern yugoslavia the aegean sea bulgaria southern romania western turkey fit a straight line very well with the p velocity equal to 7 9 f 0 1 km s on the contrary the travel times of p waves to stations in the western part of the area albania western greece do not fit this curve because the p waves travelling to these stations are delayed by more than 1 s due to the thicker crust under the dinarides hellenides mountain range time delays for p waves have been calculated for each permanent station in the balkan area with respect to the mean travel time curve of these waves in the central and eastern part of the area corrections of the travel times for these delays contribute very much to the improvement of the accuracy in the location of the shallow earthquakes in the aegean and surrounding area

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

ammonoid recovery after the permian triassic mass extinction a re exploration of morphological and phylogenetic diversity patterns the explosive ammonoid rediversification after the permian triassic mass extinction is now well understood in terms of taxonomic richness and biogeography using an updated dataset of early triassic ammonoids we compare morphological disparity and taxonomic richness patterns at the regional and global scales disparity evolved similarly at both scales suggesting a global influence of abiotic factors morphological diversification occurred early in the smithian and a marked contraction of the morphospace took place during the end smithian extinction we confirm that trends in disparity and richness were decoupled during the griesbachian and dienerian three macroevolutionary processes may be involved 1 a nonselective extinction at the permian triassic boundary 2 a dienerian constrained radiation with several homeomorphic genera 3 a potential deterministic extinction during the end smithian crisis we also demonstrate a superfamily imprint upon disparity for the spathian when most superfamilies occupied a restricted part of the morphospace sphaerocones were the most affected by the dienerian and end smithian extinction but explanations remain elusive on the one hand this may be linked to widespread harsh conditions at those times on the other hand as the sphaerocones occurred episodically during the early triassic this might be explained by a relaxing of ecological constraints or simply by convergent evolution supplementary materials the database including measurements of specimens illustrated in previously published plates and of unpublished specimens from utah south china and spiti as well as the number of genera present in each studied substage of the early triassic are available at www geolsoc org uk sup18571

s wave attenuation in the crust in northern greece abstract the attenuation of shear waves in the crust is estimated for frequencies between 1 5 and 12 0 hz by applying a single station method based on the rate of decay of the s wave to coda wave amplitude ratio with distance the data used come from local earthquakes that occurred in the thessaloniki area northern greece during the period 1983 through 1989 and were recorded by the telemetered network of the geophysical laboratory of the university of thessaloniki the q s values obtained are 115 244 477 and 755 for 1 5 3 0 6 0 and 12 0 hz respectively these values are very close to the coda q values estimated for the same area using the s to s single scattering model for lapse times between 30 and 100 sec but they are higher than the coda q values for lapse times between 10 and 30 sec the estimated q s is found to be strongly frequency dependent proportional to f 0 91 which is very close to the frequency dependence of the coda q

timing of the early triassic carbon cycle perturbations inferred from new u pb ages and ammonoid biochronozones based on analyses of single thermally annealed and chemically abraded zircons a new high precision u pb age of 251 22 0 20 ma is established for a volcanic ash layer within the kashmirites densistriatus beds of early smithian age early triassic from the luolou formation northwestern guangxi south china this new date together with recalculated uncertainties of previous u pb ages from the same section m ovtcharova h bucher u schaltegger t galfetti a brayard j guex new early to middle triassic u pb ages from south china calibration with ammonoid biochronozones and implications for the timing of the triassic biotic recovery earth planet sci lett 243 2006 463 475 allows constraining the time framework of the early triassic and leads to an estimated duration of i ca 0 7 0 6 my for the smithian and ii a maximal duration of ca 1 4 0 4 my for the griesbachian dienerian time interval the new u pb age considerably reduces the absolute age gap comprised between the permian triassic boundary and the spathian late early triassic the new age framework provides the basis for the calibration of a new carbonate carbon isotope and ammonoid records of the early triassic luolou fm which in turn are of high significance for global correlations and for carbon cycle modeling this calibration indicates that the most significant and fastest early triassic carbon isotope perturbations occur between the earliest smithian and the early spathian thus spanning a time interval of about 1 my whatever caused these carbon cycle shifts of high intensity and short duration there is evidence for connections between these fluctuations the pulsate recovery of ammonoids and conodonts as well as climate changes

deterministic ground motion scenarios for engineering applications the case of thessaloniki greece abstract in this article we present a deterministic study to estimate seismic ground motions expected in urban areas located near active faults the purpose was to generate bedrock synthetic time series to be used as seismic input into site effects evaluation analysis and loss estimates for the urban area and infrastructures of thessaloniki northern greece two simulation techniques a full wave method to generate low frequency seismograms 1 hz were used to compute time series associated with four different reference earthquakes having magnitudes from 5 9 to 6 5 and located within 30 km of thessaloniki the propagation medium and different source parameters were tested through the modeling of the 1978 thessaloniki earthquake m 6 5 moreover two different nucleation points were considered for each fault in order to introduce additional variability in the ground motion estimates between the two cases the quasi unilateral rupture propagation toward the city produces both higher median peak ground acceleration pga and peak ground velocity pgv values and higher variability than bilateral ones conversely the low frequency ground motion that is peak ground displacement pgd is slightly influenced by the position of the nucleation point and its variability is related to the final slip distribution on the faults of the reference earthquakes and to the location of the sites with respect to the nodal planes of the radiation pattern to validate our deterministic shaking scenarios we verified that the synthetic peak ground motions pga and pgv and spectral ordinates are within one standard deviation of several ground motion prediction equations valid for the region at specific sites we combined the low and high frequency synthetics to obtain broadband time series that cover the entire frequency band of engineering interest 0 25 hz the use of synthetic seismograms instead of empirical equations in the hazard estimates provides a complete evaluation of the expected ground motions both in frequency and time domains including predictions at short distances from the fault 0 10 km and at periods larger than 2 3 sec

the 1978 earthquake sequence near thessaloniki northern greece summary this paper presents a detailed study of teleseismically and locally recorded foreshocks and aftershocks of the 1978 thessaloniki earthquake sequence and discusses the relations between the locations and mechanisms of these shocks and the three dimensional geometry of faulting in the source region sixteen teleseismically recorded events were relocated using a relative relocation method and positioned geographically using the accurate locally determined location of the largest aftershock all these shocks had depths shallower than 15 km the spatial distribution of the foreshocks showed that the activity was initiated at the central part of the epicentral region progressed westwards and for about 20 days clustered in the region of the imminent mainshock no teleseismically recorded foreshock was located west of the mainshock location in less than 1 hr after the mainshock large aftershocks occurred west of it and in later stages spanned the entire western part of the epicentral region no teleseismically recorded aftershocks were located east of the mainshock locally recorded aftershocks were accurately located and provided a more detailed picture of the seismic deformation they occurred at depths between 3 and 12 km and in three distinct clusters separated by well defined gaps the largest foreshock on may 23 had a moment of 5 6 1024dyne cm and a mean displacement of 31cm the mainshock on june 20 had a moment of 5 2 1025dyne cm a strain drop of 4 0 10 5 static stress drop of 12 bar and a mean displacement of 64 cm these values are for one of the two possible interpretations of the aftershock distribution which suggests that the largest earthquakes of the sequence occurred on two different but adjacent fault segments the first event 1 on may 23 occurred along the central fault segment and was followed 28 days later by the second event 2 on june 20 along a western fault segment finally 61 days later another smaller earthquake event 3 occurred along another fault east of event 1

simulating permian triassic oceanic anoxia distribution implications for species extinction and recovery the biggest mass extinction in the phanerozoic at the end of the permian has been associ ated with oceanic changes but the exact dynamics are still debated intensifi ed stratifi cation widespread anoxia chemocline excursions and large scale ocean overturn events have all been invoked as contributors to the extinction in this study the effects of possible changes in environmental conditions such as an increase in nutrient input or dust fl uxes into the ocean or an intensifi cation of the biological pump on permian triassic ocean chemistry are inves tigated series of sensitivity experiments were performed with a fully coupled climate carbon cycle model none of the forcings alone generates extensive low oxygen conditions in the deep sea these are only simulated by an intense eutrophication in combination with an enhanced biological pump but still confi ned to the central panthalassic tethys and the eastern boreal oceans our fi ndings support the conclusions from a recent geochemical study of a japanese deep panthalassa section that around the permian triassic boundary the oxygen minimum zone expanded considerably while the deep panthalassa remained ventilated the warming induced increase in low oxygen conditions within the water column aggravated adverse exist ing conditions and likely contributed to the extinction peak upwelling of toxic water was probably regionally confi ned and hence not the main cause for the end permian marine and terrestrial mass extinction widespread deep sea anoxia generated by a strong increase in weathering and the related enhanced nutrient input into the oceans is probably closely linked to the delayed recovery of species in the early triassic

temporal evolution of surface rupture deduced from coseismic multi mode secondary fractures insights from the october 8 2005 mw 7 6 kashmir earthquake nw himalaya abstract detailed rupture fracture analyses of some of the well studied earthquakes have revealed that the geometrical arrangement of secondary faults and fractures can be used as a geological tool to understand the temporal evolution of slip produced during the mainshock the october 8 2005 mw 7 6 kashmir earthquake nw himalaya surface rupture provides an opportunity to study a complex network of secondary fractures developed on the hanging wall of the fault scarp the main fault scarp is clearly thrust type rupture length is 75 5 km and the overall trend of the rupture is nw se we present the results of our detailed structural mapping of secondary faults and fractures at 1 100 scale on the hanging wall of the southern end of the rupture in the vicinity of the sar pain secondary ruptures can be broadly classified as two main types 1 normal faults and 2 right lateral strike slip riedel fractures the secondary normal faults are nw se striking with a maximum 3 3 meter vertical displacement and 2 5 meter horizontal displacement estimated total horizontal extension across the secondary normal faults is 3 1 3 5 we propose that the bending moment and coseismic stress relaxation can explain the formation of secondary normal faults on the hanging wall of the thrust fault the strike slip riedel fractures form distinct sets of tension t and shear fractures r r y with right lateral displacement field observations revealed that the riedel fractures t cut the secondary normal faults in addition there is kinematic incompatibility and magnitude mismatch between the secondary normal faults and strike slip riedel fractures the cross cutting relationship geometric and magnitude incoherence implies a temporal evolution of slip from dip to strike slip during the mainshock faulting the interpretation is consistent with the thrust fault plane solution with minor right lateral strike slip component

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

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

the early triassic ammonoid recovery paleoclimatic significance of diversity gradients ammonoids recovered much faster than other marine shelly invertebrates after the end permian mass extinction based on a refined global data set at the basin level we investigate the paleobiogeographical global latitudinal and longitudinal diversity patterns in terms of climatic changes during the early triassic such analysis differs from already published qualitative or quantitative studies in that it estimates faunal patterns and endemicity at an ecologically meaningful level of spatial resolution i e at the basin level during the early triassic the global first order trend in increasing ammonoid diversity was accompanied by a progressive change from cosmopolitan to latitudinally restricted distributions this led to the emergence of a clear latitudinal diversity gradient during most of the smithian and spathian stages which entails increased steepness of the sea surface temperature gradient during the late early triassic however two brief episodes of ammonoid cosmopolitanism combined with low global diversity interrupted the first order increasing trend at the very beginning of the smithian and at its very end the longitudinal analysis of smithian distributions indicates a westward decrease of diversity within the tethys which faded away during the spathian analysis of endemicity indicates a rapid biogeographical maturing and structuring of faunas concomitant with the edification of the latitudinal diversity gradient

site effects in the city of thessaloniki greece estimated from acceleration data and 1d local soil profiles abstract in this study the site effects on seismic ground motion in the city of thessaloniki greece are estimated by applying experimental methods on acceleration data and theoretical modeling the technique of standard spectral ratio ssr is applied to a reference station located on rock while the horizontal to vertical spectral ratio hvsr technique is applied to earthquake records entire record length including p and s waves as well as on noise recordings in addition the ssr method is also applied to the vertical components the results from all methods are compared in terms of resonant frequencies and amplification levels the fundamental resonant frequency is identified by all methods while the average amplification level is generally underestimated when the hvsr technique is used an attempt is made to correlate the site amplifications computed in this study with the observed macroseismic intensities reported at the same sites for the 20 june 1978 earthquake a relation of the form i b log s s f is derived where i is the intensity increment with respect to the intensity of the reference station and ssr is the mean amplification factor obtained at each station using the ssr technique for a certain frequency band in the numerical approach we construct complete strong motion synthetics using the modal summation method for the p sv waves up to frequencies of 10 hz as input four point sources are used located at different distances and azimuths from the stations ratios of response spectra of the local 1d over the regional 1d synthetic seismograms are calculated the obtained mean spectral amplifications are compared with those derived from experimental data and the two sets are found to be consistent at most stations

permian triassic boundary interval in the middle east iran and n oman progressive environmental change from detailed carbonate carbon isotope marine curve and sedimentary evolution abstract the end permian negative 13c excursion is well known but its cause and chronology are still in question in an attempt to decipher the timing and reasons for this strong decrease we established high resolution sedimentological biostratigraphical and carbonate carbon isotopic studies in four sections in iran abadeh shareeza zal and djulfa and two in oman wadi sahtan the position of the sections on two different margins of the neotethys has allowed us to distinguish between local and global signals this high resolution chemostratigraphy tested for isochrony on the basis of an updated high resolution conodont and ammonoid biostratigraphy allows the discrimination of nine successive isotopic events ie 0 8 for the permian triassic boundary interval ptbi the negative excursion of the ptbi has been separated into four distinct parts a first drop ie 0 occurs in the late wuchiapingian with an amplitude of around 1 3 a second decrease begins ie 1 2 at the base of the dzhulfites ammonoid beds changhsingian and continues gradually until the extinction event top jolfensis conodont interval without important second order variations its amplitude varies between 1 5 and 2 8 and its duration has been estimated around 2 2 ma revealing a non catastrophic phenomenon the lower meishanensis praeparvus conodont zone records stationary to slightly increasing values ie 3 the interval of the curve after the extinction event between the upper meishanensis praeparvus zone and the base of the i isarcica zone records numerous second order variations ie 4 7 its amplitude is of 1 2 3 1 these second order variations are correlatable in iran but with some uncertainty with oman poor correlation of these small peaks with others published sections might be due to a higher sensitivity to local perturbations and a lower buffer capacity of the whole ocean we assume that the processes leading to the extinction event also caused the isotopic decrease before the extinction level with a maximal amplitude of only 2 8 this allows consideration of some possible mechanisms that were rejected as unrealistic to cause a 4 6 excursion

conodont diversity and evolution through the latest permian and early triassic upheavals abstract a study of latest permian and early triassic multielement conodonts identifies eight steps in their evolutionary history during an interval when earth s biosphere was highly stressed these steps are 1 gradual decline of families and genera through the changhsingian up to the late griesbachian 2 conodont biofacies change and extinction of tethyan endemic species close to the permian triassic boundary ptb 3 faunal turnover with extinction and origination in the late griesbachian 4 initial radiation in gondolellids and diversification in apparatuses during the dienerian 5 explosive radiation in the early middle smithian 6 major extinction in the late smithian 7 major radiation early in the spathian 8 gradual turnover and decline in the late spathian through early anisian conodontophorids were reduced from five families at the beginning of the changhsingian to three by the ptb and to two late in the griesbachian from the changhsingian to the late griesbachian there was a single multielement apparatus represented in the gondolellidae whereas by the olenekian there were at least twelve given absolute age constraints the conodont recovery in the aftermath of the ptb was extraordinary conodont evolution during the dienerian remains obscure but was very significant in terms of changes in multielement apparatuses in spite of induan extinctions generic diversity generally increased from the ptb up to the late smithian in terms of species genera and multielement apparatuses the acme of triassic conodonts was in the middle smithian and the biggest extinction was in the late smithian after this extinction generic and apparatus diversity quickly returned to high levels marking a significant spathian recovery gradual decline characterized the late spathian and persisted into the early anisian a synthetic summary of the temporal distribution and proposed relationships amongst all known lower triassic conodonts provide an improved foundation for biostratigraphic and biochronologic studies extinction and radiation trends correlate well with sea level changes and sequence boundaries faunal turnovers correspond to lowstands in the late griesbachian late smithian and late spathian and radiations correspond to transgressions in the early griesbachian early smithian and early spathian the trends also correlate with perturbations in the carbon cycle with lower triassic 13c minima corresponding to extinction and faunal turnover and positive values generally occurring during radiations however middle triassic recovery of marine benthos follows a positive maxima and an overall decline in conodont diversity new taxa borinella chowadensis b megacuspa neogondolella griesbachensis and n mongeri are described

geodetic constraints on the fault pattern of the 1978 thessaloniki northern greece earthquake ms 6 4 summary repeated measurement of a 110 km long high precision spirit levelling traverse indicates that between 1958 and 1978 about 25 cm of subsidence occurred along a distance of 30 km in the mygdonian quaternary graben near thessaloniki northern greece observed displacements are significant against random and systematic errors and most are unrelated to near surface effects and can be assigned to the 1978 thessaloniki destructive earthquakes the available data do not permit a formal inversion but an elastic dislocation analysis indicates that the main shock of the seismic sequence ms 6 4 was probably associated with a ne dipping wnw trending blind normal fault marking the southwestern margin of the mygdonian graben in agreement with seismological and structural data there also exists evidence for incipient faulting in the central southern part of the mygdonian graben

large perturbations of the carbon cycle during recovery from the end permian extinction high resolution carbon isotope measurements of multiple stratigraphic sections in south china demonstrate that the pronounced carbon isotopic excursion at the permian triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the early triassic before ending abruptly early in the middle triassic the unusual behavior of the carbon cycle coincides with the delayed recovery from end permian extinction recorded by fossils suggesting a direct relationship between earth system function and biological rediversification in the aftermath of earth s most devastating mass extinction

response to comment on lethally hot temperatures during the early triassic greenhouse goudemand et al replot a subset of our well constrained data using a new early triassic biostratigraphic scheme based on a lower resolution ammonoid zonation scheme and hypothetical ammonoid conodont correlation to produce a less distinct seawater temperature history we dispute their unsubstantiated correlation and consequently their allegations

smithian and spathian early triassic ammonoid assemblages from terranes paleoceanographic and paleogeographic implications early triassic paleobiogeography is characterised by the stable supercontinental assembly of pangea however at that time several terranes such as the south kitakami massif sk south primorye sp and chulitna respectively and presently located in japan eastern russia and alaska straddled the vast oceans surrounding pangea by means of quantitative biogeographical methods including cluster analysis non metric multidimensional scaling and bootstrapped spanning network applied to smithian and spathian early triassic ammonoid assemblages we analyze similarity relationships between faunas and suggest paleopositions for the above cited terranes taxonomic similarities between faunas indicate that primary drivers of the ammonoid distribution were sea surface temperature and currents possible connections due to current controlled faunal exchanges between both sides of the panthalassa are shown and terranes such as sk sp and chulitna played an important role as stepping stones in the dispersal of ammonoids sk and sp terranes show strong sub equatorial affinities during the smithian thus suggesting a location close to south china at the same time the chulitna terrane shows strong affinities with equatorial faunas of the eastern panthalassa this paleoceanographic pattern was markedly altered during the spathian possibly indicating significant modifications of oceanic circulation at that time as illustrated by the development of a marked intertropical faunal belt across tethys and panthalassa

latest permian to middle triassic cyclo magnetostratigraphy from the central european basin germany implications for the geomagnetic polarity timescale in central germany the about 1 km thick mainly clastic germanic lower triassic buntsandstein consists of about 60 sedimentary cycles which are considered to reflect variability in precipitation within the epicontinental central european basin most probably due to solar induced short eccentricity cycles they provide a high resolution cyclostratigraphic framework that constitutes the base for creating a composite geomagnetic polarity record in which this paper presents a middle buntsandstein to lowermost muschelkalk magnetostratigraphy obtained from 6 outcrops and 2 wells where a total of 471 samples was collected combined with recently established records a well documented magnetostratigraphy for the upper zechstein to lowermost muschelkalk latest permian to middle triassic of central germany has been constructed encompassing an overall stratigraphic thickness of about 1 3 km and 22 magnetozones derived from about 2050 paleomagnetic samples along with available biostratigraphy this multi disciplinary study facilitates detailed links to the marine realm in order to directly refer biostratigraphically calibrated triassic stage boundaries as well as radioisotopic ages to the buntsandstein cyclostratigraphy and conversely to contribute to calibrating the geologic timescale 2007 elsevier b v all rights reserved

comment on lethally hot temperatures during the early triassic greenhouse sun et al reports 19 october 2012 p 366 reconstructed permian to middle triassic equatorial seawater temperatures after correct temporal positioning of their data points their presumed trends of temperature changes and hence their assumption of a one to one relationship between putative lethally hot seawater temperatures and a disputable equatorial eclipse of some organisms are no longer supported by their data

thessaloniki s detailed microzoning subsurface structure as basis for site response analysis the city of thessaloniki is located in northern greece close to a large seismogenic area and it has experienced several destructive earthquakes during the present century in this paper we focus on the definition of the subsurface structure of the city from a site response analysis perspective the paper presents together with a summary of geology and seismicity the results of a large scale geophysical and geotechnical survey in order to determine and validate geometry and dynamic properties of the main soil formations the synthesis and combination of recent results regarding the dynamic properties with those obtained from the elaboration of a large database of classical geotechnical tests led to the design of a detail geotechnical map and of various 1 d profiles 2 d cross sections and 3 d thematic maps for the main soil formations these soil profiles and maps are oriented to site effect studies and provide a comprehensive picture easily adapted to geographic information systems gis for planning and design purposes moreover the results of this study were correlated with macroseismic observations reported in many earlier published microzonation studies of thessaloniki these comparative observations revealed the complexity of surface geology of the urban area a fact which is expected to provoke additional amplification with respect to 1 d resonance

thessaloniki gerakarou fault zone tgfz the western extension of the 1978 thessaloniki earthquake fault northern greece and seismic hazard assessment abstract active faulting and seismic properties are re investigated in the eastern precinct of the city of thessaloniki northern greece which was seriously affected by two large earthquakes during the 20th century and severe damage was done by the 1759 event it is suggested that the earthquake fault associated with the occurrence of the latest destructive 1978 thessaloniki earthquake continues westwards to the 20 km long thessaloniki gerakarou fault zone tgfz which extends from the gerakarou village to the city of thessaloniki this fault zone exhibits a constant dip to the n and is characterised by a complicated geometry comprised of inherited 100 trending faults that form multi level branching tree like fault geometry along with nne to ne trending faults the tgfz is compatible with the contemporary regional n s extensional stress field that tends to modify the pre existing nw se tectonic fabric prevailing in the mountainous region of thessaloniki both the 1978 earthquake fault and tgfz belong to a ca 65 km long e w trending rupture fault system that runs through the southern part of the mygdonia graben from the strymonikos gulf to thessaloniki this fault system here called thessaloniki rentina fault system trfs consists of two 17 20 km long left stepping 100 trending main fault strands that form underlapping steps bridged by 8 10 km long ene wsw faults the occurrence of large m 6 0 historical earthquakes in 620 677 and 700 a d demonstrates repeated activation and therefore the possible reactivation of the westernmost segment the tgfz could be a major threat to the city of thessaloniki changes in the coulomb failure function cff due to the occurrence of the 1978 earthquake calculated out in this paper indicate that the tgfz has been brought closer to failure a convincing argument for future seismic hazard along the tgfz

gastropod evidence against the early triassic lilliput effect comment brayard et al 2010 1 assert that their study of late early triassic gastropods provides evidence against the post extinction lilliput effect regrettably their data provide no such evidence the lilliput effect as defined by urbanek 1993 2 is a quantifiable temporary decrease in the

attenuation of coda waves in northern greece the single scattering model has been applied for the estimation of codaq values for local earthquakes that occurred in northern greece during the period 1983 1989 and recorded by the telemetered network of the geophysical laboratory of the university of thessaloniki codaq estimations were made for four frequency bands centered at 1 5 hz 3 0 hz 6 0 hz and 12 0 hz and for the lapse time windows 10 20 sec 15 30 sec 20 45 sec 30 60 sec and 50 100 sec the codaq values obtained show a clear frequency dependence of the formq c q 0 f n whileq 0 andn depend on the lapse time window q 0 was found equal to 33 andn equal to 1 01 for the time window of 10 to 20 sec while for the other windowsq 0 increased from 60 to 129 withn being stable close to 0 75 this lapse time dependence is interpreted as due to a depth dependent attenuation the high attenuation and the strong frequency dependence found are characteristic of an area with high seismicity in agreement with studies in other seismic regions

uranium isotopes distinguish two geochemically distinct stages during the later cambrian spice event a b s t r a c t anoxic marine zones were common in early paleozoic oceans 542 400 ma and present a potential link to atmospheric po2 via feedbacks linking global marine phosphorous recycling primary production and organic carbon burial uranium u isotopes in carbonate rocks track the extent of ocean anoxia whereas carbon c and sulfur s isotopes track the burial of organic carbon and pyrite sulfur primary long term sources of atmospheric oxygen in combination these proxies therefore reveal the comparative dynamics of ocean anoxia and oxygen liberation to the atmosphere over million year time scales here we report high precision uranium isotopic data in marine carbonates deposited during the late cambrian spice event at ca 499 ma documenting a well defined 0 18 negative 238 u excursion that occurs at the onset of the spice event s positive 13

lower triassic conodont sequence in chaohu anhui province china and its global correlation abstract the early triassic paleogeographical setting of the chaohu section in china was in a deep part of the yangtze platform and this has resulted in a rather complete lower triassic sequence with rich ammonoid and conodont successions three lower triassic sections west pingdingshan north pingdingshan and south majiashan have been sampled in detail for a systematic conodont study eight conodont zones are recognized in ascending order these are the zones of hindeodus typicalis neogondolella krystyni neospathodus kummeli neospathodus dieneri neospathodus waageni neospathodus pingdingshanensis neospathodus homeri and neospathodus anhuinensis these are correlated with the sequences in north america and other areas of the world the succession provides a good basis for the definition of the global stratotype of the induan olenekian boundary gssp which has been proposed at the base of the neospathodus waageni zone in west pingdingshan seven new species are introduced neospathodus chaohuensis n chii n concavus n eotriangularis n pingdingshanensis n posterolongatus n tongi a new subspecies n waageni eowaageni and three morphotypes of n dieneri

magnitude versus faults surface parameters quantitative relationships from the aegean region historical and seismotectonic data from the broader aegean region have been collected and all possible information relative to ground deformation associated to earthquakes that hit the area have been re evaluated all events associated to co seismic surface faulting have been selected and further investigated while geomorphologic and geological criteria have been used to recognise and characterise the seismogenic faults associated to these morphogenic earthquakes sensu bull inqua 16 1993 24 in particular in order to perform seismic hazard analyses we compiled a list of all earthquakes where the surface rupture length srl the maximum vertical displacement mvd or the average displacement ad is available we thus obtained reliable values of these source parameters for 36 earthquakes of which 26 occurred during the 20th century 6 in the 19th century and the 3 remaining earlier magnitude versus srl and mvd has been compiled for estimating empirical relationships the calculated regression equations are ms 0 90 log srl 5 48 and ms 0 5 9log mvd 6 75 showing good correlation coefficients equal to 0 84 and 0 82 respectively co seismic fault rupture lengths and especially maximum displacements in the aegean region have systematically lower values than the same parameters worldwide but are similar to those of the eastern mediterranean middle east region the envelopes of our diagrams are also calculated and discussed for estimating the worst case scenario furthermore for all investigated seismogenic structures based on several geological criteria we measured the geological fault length gfl which is the total length of the neotectonic faults showing cumulative recent activity we then compared srl with gfl and their ratio shows a clear bimodal distribution with a major peak at 0 8 1 0 indicating that about 50 of the investigated earthquakes ruptured almost the entire fault length while a second peak around the value of 0 5 is clearly related to a segmentation process of longer neotectonic structures further implications of this distribution are also discussed eventually from the distribution of gfl versus magnitude we also infer an important geological threshold for the occurrence of morphogenic earthquakes at about 5 5 degrees

isotopic evidence for an anomalously low oceanic sulfate concentration following end permian mass extinction abstract the cataclysmic end permian mass extinction was immediately followed by a global expansion of microbial ecosystems as demonstrated by widespread microbialite sequences disaster facies in shallow water settings here we present high resolution carbonate carbon 13 c carb and carbonate associated sulfate sulfur isotope 34 s cas records from the microbialite in the cili permian triassic p tr section in south china a stepwise decline in 13 c carb begins in the underlying skeletal limestone predating the main oceanic mass extinction and the first appearance of microbialite and reaches its nadir in the upper part of the microbialite layer the corresponding 34 s cas in the range of 17 4 to 27 4 is relatively stable in the underlying skeletal limestone and increases gradually from 2 m below the microbialite rising to a peak at the base of the microbialite two episodes of positive and negative shifts occurred within the microbialite layer and exhibit a remarkable co variance of sulfur and carbon isotope composition the large amplitude of the variation in 34 s cas as high as 7 per 100 kiloyears suggests a small oceanic sulfate reservoir size at this time furthermore the 13 c carb and 34 s cas records co vary without phase lag throughout the microbialite interval implying a marine driven c cycle in an anoxic ocean with anomalously low oceanic sulfate concentrations on the basis of a non steady state box model we argue that the oceanic sulfate concentration may have fallen to less than 15 perhaps as low as 3 of that in the modern oceans low oceanic sulfate concentration likely was the consequence of evaporite deposition and widespread anoxic sulfidic conditions prior to the main mass extinction by promoting methanogenesis and a build up of atmospheric ch 4 and co 2 low oceanic sulfate may have intensified global warming exacerbating the inimical environmental conditions of the latest permian

marine anoxia and delayed earth system recovery after the end permian extinction delayed earth system recovery following the end permian mass extinction is often attributed to severe ocean anoxia however the extent and duration of early triassic anoxia remains poorly constrained here we use paired records of uranium concentrations u and 238u 235u isotopic compositions 238u of upper permian upper triassic marine limestones from china and turkey to quantify variations in global seafloor redox conditions we observe abrupt decreases in u and 238u across the end permian extinction horizon from 3 ppm and 0 15 to 0 3 ppm and 0 77 followed by a gradual return to preextinction values over the subsequent 5 million years these trends imply a factor of 100 increase in the extent of seafloor anoxia and suggest the presence of a shallow oxygen minimum zone omz that inhibited the recovery of benthic animal diversity and marine ecosystem function we hypothesize that in the early triassic oceans characterized by prolonged shallow anoxia that may have impinged onto continental shelves global biogeochemical cycles and marine ecosystem structure became more sensitive to variation in the position of the omz under this hypothesis the middle triassic decline in bottom water anoxia stabilization of biogeochemical cycles and diversification of marine animals together reflect the development of a deeper and less extensive omz which regulated earth system recovery following the end permian catastrophe

climatic and biotic upheavals following the end permian mass extinction the recovery from the end permian mass extinction was slow and prolonged a temperature reconstruction shows that further biotic crises during the recovery were associated with extreme warmth

astronomical tuning of the end permian extinction and the early triassic epoch of south china and germany abstract the timing of the end permian mass extinction and subsequent prolonged recovery during the early triassic epoch can be established from astronomically controlled climate cycles recorded in continuous marine sedimentary sections astronomical cycle tuning of spectral gamma ray logs from biostratigraphically constrained cyclic stratigraphy through marine sections at meishan chaohu daxiakou and guandao in south china yields an integrated time scale for the early triassic which is consistent with scaling of magnetostratigraphy from climatic cycles in continental deposits of the germanic basin the main marine mass extinction interval at meishan is constrained to less than 40 of a 100 kyr kilo year cycle i e c 13 is estimated to have lasted c 13 from 2 to 4 across the smithian spathian boundary at chaohu was completed in 50 kyr the earliest marine reptiles in the mesozoic at chaohu that are considered to represent a significant recovery of marine ecosystems did not appear until 4 7 myr million years after the end permian extinction the durations of the griesbachian dienerian smithian and spathian substages including the uncertainty in placement of widely used conodont biostratigraphic datums for their boundaries are 1 4 0 1 0 6 0 1 1 7 0 1 and 1 4 0 1 myr implying a total span for the early triassic of 5 1 0 1 myr therefore relative to an assigned 251 902 0 024 ma for the permian triassic boundary from the meishan gssp the ages for these substage boundaries are 250 5 0 1 ma for base dienerian 249 9 0 1 ma for base smithian base of olenekian stage 248 2 0 1 ma for base spathian and 246 8 0 1 ma for the base of the anisian stage this astronomical calibrated timescale provides rates for the recurrent carbon isotope excursions and for trends in sedimentation accumulation through the early triassic of studied sections in south china

seismotectonic evidence of an active normal fault beneath thessaloniki greece during 3 weeks in 1985 we operated a dense network of portable seismological stations around the city of thessaloniki in northern greece where a destructive earthquake had occurred in 1978 we recorded 282 microearthquakes with magnitudes ranging between 0 2 to 3 0 and we computed 22 fault plane solutions the experiment was designed to map the stress pattern west of the 1978 shock and to study the asvestohorio fault around this fault located near thessaloniki mercier et al 1983 observed a few cracks during the 1978 shock the seismicity shows the same scattered pattern seen through the whole chalkidiki region we observe also a dense cluster around asvestohorio but this cluster is probably related to explosions in nearby mines after filtering the data from possible explosions we found evidence of seismic activity the earthquakes are dipping toward the ne suggesting that the asvestohorion fault is active the fault plane solutions do not help in defining the geometry of the fault but the p and t axes are consistent with the regional stress pattern

irregular glacial interstadials recorded in a new greenland ice core the greenland ice sheet offers the most favourable conditions in the northern hemisphere for obtaining high resolution continuous time series of climate related parameters profiles of 18o 16o ratio along three previous deep greenland ice cores1 3 seemed to reveal irregular but well defined episodes of relatively mild climate conditions interstadials during the mid and late parts of the last glaciation but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate rather than artefacts due to disturbed stratification here we present results from a new deep ice core drilled at the summit of the greenland ice sheet where the depositional environ ment and the flow pattern of the ice are close to ideal for core recovery and analysis the results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt according to a preliminary timescale based on stratigraphic studies the interstadials lasted from 500 to 2 000 years and their irregular occurrence suggests complexity in the behaviour of the north atlantic ocean circulation

terrestrial marine teleconnections in the collapse and rebuilding of early triassic marine ecosystems abstract the latest permian mass extinction lpe just prior to the permian triassic boundary at 252 ma resulted in the disappearance of 90 of skeletonized marine taxa and the replacement of the paleozoic fauna by the modern fauna in the immediate aftermath of the extinction shallow marine ecosystems were dominated by microbial communities and diminutive disaster taxa lilliput faunas and the post crisis period in general was characterized by high abundance low diversity marine communities occupying a reduced ecological space the recovery of marine ecosystems was a protracted process lasting throughout the 5 myr long early triassic some clades failed to recover and subsequently went extinct dead clades walking while others recovered only to suffer secondary crises during the early triassic profound environmental changes accompanied these biotic developments deep oceans experienced sustained hypoxia or anoxia for at least several million years following the boundary event anoxia was also widespread in shallow marine areas especially at the time of the lpe but it was more episodic and abated more rapidly than in the deep ocean making it an unlikely factor in the delayed recovery of early triassic marine ecosystems the development of anoxia was due at least in part to a sharp temperature rise following the lpe but may have been stimulated by changes in marine nutrient inventories and productivity rates as well these conditions may have been the result of a concurrent increase in subaerial weathering rates that was sustained into the early triassic in addition to increasing nutrient fluxes to marine areas rapid weathering caused a massive influx of sediment to shallow marine systems subjecting marine biotas to siltation stress this scenario implies close teleconnections between terrestrial and marine environments during the permian triassic boundary crisis with perturbations of the terrestrial realm contributing to the marine crisis

quantitative biochronology of the permian triassic boundary in south china based on conodont unitary associations abstract the biochronological characterization of the permian triassic boundary ptb is here improved by means of conodont unitary associations zones uazs the selected data set comprises the six best documented sections in south china including the meishan global stratotype section and point of the ptb this new biochronological zonation has a much higher accuracy than previous schemes which were based on continuous interval zones we show how traditional interval zones around the ptb in south china suffer from diachronous boundaries that cross each other as the result of sampling effort intensity and density and of geographical or ecological exclusion of zonal index taxa inclusive of the first occurrence of the base triassic index species hindeodus parvus our quantitative and robust approach produces a discrete sequence comprising six uazs in the closest agreement with the position of the ptb in meishan the ptb falls here in the interval of separation between uaz 2 and uaz 3 in meishan this interval of separation corresponds to the stratigraphic interval above bed 25 and below bed 27 which also includes the formational boundary between the changhsing and the yinkeng formations we provide a new and independent support for this placement by showing that it correlates with the main turnover of conodont species within the analysed time interval as previously documented the main extinction interval ranged from bed 25 to bed 28 in meishan which are here assigned to uaz 2 and to uaz 4 respectively therefore the main extinction episode is not of end permian age but straddles the ptb previous claims for two distinct extinction pulses bracketing the ptb in south china were based on traditional conodont interval zones and are not supported by the new ua zonation the oldest triassic uaz 3 is identified by the characteristic species hindeodus pisai and by any of the ten characteristic pairs of species neogondolella zhejiangensis or neogondolella tulongensis associated with hindeodus changxingensis hindeodus parvus neogondolella planata neogondolella taylorae or isarcicella huckriedei separate analyses of anchignathodontids and neogondolellids sub data sets show that the base of the triassic is unambiguously defined by the occurrences of the characteristic species h changxingensis isarcicella prisca and i huckriedei in shallow water settings and of two characteristic species n planata and n taylorae in deep water settings moreover we document uncoupled diversity trends across the ptb for each of these two clades a substantial diversification phase of anchignathodontids spans the interval from uaz 3 to uaz 5 it is followed by a drastic 50 reduction of the number of species between uaz 5 and uaz 6 on the other hand neogondolellids show a protracted extinction from uaz 4 to uaz 6 in south china correlations are proposed for the microbialite bearing sections and deeper water ptb sections the ua method also highlights which parts of the conodont record are still insufficiently documented for reliable correlations biochronological correlations with meishan and its u pb radio isotopic ages allow inferring a maximal duration of 61 48 ka for the gap at the base of the triassic microbial limestone at dajiang a time interval that also corresponds to the duration of the main extinction episode in meishan

rapid expansion of oceanic anoxia immediately before the end permian mass extinction tive of an expansion of oceanic anoxia and higher th u ratios from 0 06 to 0 42 indicative of drawdown of u concentrations in seawater using a mass balance model we estimate that this isotopic shift represents a sixfold increase in the flux of u to anoxic facies implying a corresponding increase in the extent of oceanic anoxia the intensification of oceanic anoxia coincided with or slightly preceded the eh and persisted for an interval of at least 40 000 to 50 000 y following the eh these findings challenge previous hypotheses of an extended period of whole ocean anoxia prior to the end permian extinction

lilliput effect in late maastrichtian planktic foraminifera response to environmental stress the lilliput effect marks morphologic and intraspecies size reductions in response to environmental stresses commonly associated with the aftermath of mass extinctions this study shows that the lilliput effect is a universal biotic response associated with greenhouse warming mesotrophic or restricted basins shallow marginal settings and volcanically active regions during the late maastrichtian sedimentary sequences analyzed from tunisia egypt texas argentina the south atlantic and indian ocean reveal that the biotic stress response appears uniform regardless of the cause varying only with the degree of biotic stress overall late maastrichtian environments span a continuum from optimum conditions to the catastrophic mass extinctions with a predictable set of biotic responses relative to the degree of stress induced by oxygen salinity temperature and nutrient variations as a result of climate and sea level changes and volcanism early stages of biotic stress result in diversity reduction and the elimination of large specialized species k strategists leading to morphologic size reduction via selective extinction disappearances and intraspecies dwarfing of survivors later stages of biotic stress result in the complete disappearance of k strategists intraspecies dwarfing of r strategists and dominance by low oxygen tolerant small heterohelicids at the extreme end of the biotic response are volcanically influenced environments which cause the same detrimental biotic effects as observed in the aftermath of the k t mass extinction including the disappearance of most species and blooms of the disaster opportunist guembelitria

evidence for end permian ocean acidification from calcium isotopes in biogenic apatite c record of carbonate rocks 13 c carb for the selective extinction of heavily calcifi ed marine animals and for the abrupt transition in carbonate facies across the extinction horizon an additional proxy is necessary to distinguish among these options calcium isotopes hold promise for differentiating between suggested scenarios for change in seawater carbonate chemistry linked with the end permian extinction the calcium cycle is linked to the carbon cycle through the weathering of limestone and the deposition of calcium carbonate sediments calcium isotopes fractionate by 0 6 and 1 3 in calcite and aragonite respectively during the precipitation of modern carbonate minerals meaning carbonate sediments are enriched in the lighter isotope relative to the seawater from which they precipitated skulan et al 1997 tang et al 2008 imbalances between calcium delivery and burial fl uxes and changes in the magnitude of fractionation during carbonate deposition will result in changes in the 44 40 ca of seawater and will be recorded in marine sediments depaolo 2004 farkao et al 2007 therefore variation in the

gastropod evidence against the early triassic lilliput effect reply size reduction in the aftermath of the permian triassic mass extinction event has repeatedly been described for various marine organisms including gastropods the lilliput effect a smithian gastropod assemblage from utah usa reveals numerous large sized specimens of different genera as high as 70 mm the largest ever reported from the early triassic other gastropods reported from serbia and italy are also as large as 35 mm size frequency distributions of the studied assemblages indicate that they were not unusually small when compared with later mesozoic and modern faunas the occurrence of large sized gastropods less than 2 ma after the permian triassic mass extinction refutes the lilliput hypothesis in this clade at least for the last 75 of the early triassic

mercury anomaly deccan volcanism and the end cretaceous mass extinction reply the contribution of the deccan traps west central india volcanism in the cretaceous paleogene kpg crisis is still a matter of debate recent u pb dating of zircons interbedded within the deccan lava flows indicate that the main eruptive phase 1 1 106 km3 of basalts initiated 250 k y before and ended 500 k y after the kpg boundary however the global geochemical effects of deccan volcanism in the marine sedimentary record are still poorly resolved here we investigate the mercury hg content of the bidart france section where an interval of low magnetic susceptibility ms located just below the kpg boundary was hypothesized to result from paleoenvironmental perturbations linked to the paroxysmal deccan phase 2 results show hg concentrations 2 orders of magnitude higher from 80 cm below to 50 cm above the kpg boundary maximum 46 6 ppb and coincident with the low ms interval increase in hg contents shows no correlation with clay or total organic carbon contents suggesting that the hg anomalies resulted from higher input of atmospheric hg species into the marine realm rather than organic matter scavenging and or increased runoff the hg anomalies correlate with high shell fragmentation and dissolution effects in planktic foraminifera suggesting correlative changes in marine biodiversity this discovery represents an unprecedented piece of evidence of the nature and importance of the deccan related environmental changes at the onset of the kpg mass extinction

latest permian mercury anomalies a sedimentary record from the buchanan lake section canadian high arctic shows anomalous high levels of mercury hg during the latest permian extinction lpe on northwest pangea significant influx of hg progressively overwhelmed the marine system major disruption of the organic matter mediated hg drawdown process resulted in accumulation of dissolved hg to maximum levels at the lpe boundary affecting an already stressed global ecosystem a switch to euxinic marine conditions at the lpe boundary led to chemical drawdown of hg sulfides as marked by progressive hg mitigation this allowed self recovery from toxic hg conditions and ultimately led to reestablishment of the internal hg organic matter drawdown process we hypothesize that anomalous hg levels may be attributed to the significant natural atmospheric emissions caused by catastrophic siberian traps volcanic eruptions

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

lilliput effect in freshwater ostracods during the permian triassic extinction abstract the lilliput effect following the permian triassic mass extinction and its aftermath has been documented in a variety of marine animal groups but it is less known in terrestrial and freshwater invertebrates here we present new investigations of the size variations of terrestrial ostracods of the genus darwinula based on fossil records from a permian triassic section on the northern limb of the dalongkou anticline section in northwest china quantitative analyses reveal that ostracod test sizes decreased sharply through the terrestrial permian triassic mass extinction interval the lilliput effect in terrestrial ostracods is characterized by the extinction of large taxa and the rise of small sized and elongate new forms coupled with the dramatic loss of conchostracans charophytes and the blooming of lycopod spores the size decrease in terrestrial ostracods following the biotic crisis through the permian triassic interval was probably triggered by several interacting events including global warming anoxia and enhanced sediment input following acid rain and wildfire

the seismology of greece abstract a review and a bibliography are given of the seismological literature for the area of greece in the period from 1950 up to the present time the aim is to incorporate all aspects of seismology starting with instrumental installations passing on to earthquake catalogues statistics and effects and ending up with structural properties and seismotectonics the purpose is to provide a service to every geophysicist who has an interest in this tectonically complex area and particularly to the numerous researchers engaged in geophysical expeditions to greece

early triassic conodonts of jiarong nanpanjiang basin southern guizhou province south china abstract jiarong huishui county guizhou province south china is a key locality for the study of the early triassic recovery after the end permian mass extinction the size reduction of conodonts at the smithian spathian transition was first documented in jiarong and it is also a locality that contributes to the documentation of the early triassic paleo seawater temperatures in the jiarong sections thirteen conodont zones were identified for the early triassic in ascending order they are hindeodus parvus zone hindeodus sosioensis zone clarkina krystyni zone neoclarkina discreta zone neospathodus cristagalli eurygnathodus costatus assemblage zone novispathodus waageni eowaageni zone novispathodus waageni waageni zone discretella discreta zone pachycladina parachirognathus assemblage zone novispathodus pingdingshanensis zone icriospathodus collinsoni zone triassospathodus homeri zone triassospathodus triangularis zone these conodont zones in the jiarong sections improve the global correlation of early triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction based on the first appearance of nv waageni eowaageni the induan olenekian boundary is recognized at 3 6 m above the base of the jiarong iii section the dominance of blade shaped segminate conodonts was replaced by gondola shaped segminiplanate conodonts twice the first time was in the late griesbachian and the second time was in the early spathian the dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late griesbachian and early spathian for short time intervals as it is believed that the griesbachian segminiplanate conodonts favored deeper oxygenated water habitats a new genus spathogondolella gen nov and a new species spathogondolella jiarongensis sp nov have been recognized

catastrophic soil erosion during the end permian biotic crisis organic geochemical analyses of sedimentary organic matter from a marine permian triassic transition sequence in northeastern italy reveal a significant influx of land derived diagenetic products of polysaccharides this unique event reflects massive soil erosion resulting from destruction of land vegetation due to volcanogenic disturbance of atmospheric chemistry the excessive supply of soil materials to the oceans provides a direct link between terrestrial and marine ecological crises suggesting that ecosystem collapse on land could have contributed to the end permian marine extinctions

seismicity focal mechanisms and tectonics in the last four years there has been a tremendous increase in the detail of tectonic processes reported in the typical seismotectonic study new data from many local and regional networks of seismographs established during the previous four year period plus the now routine application of improved hypocentral location procedures long period body wave modelling and moment tensor inversion using digitally recorded data have increased resolution of both the hypocentral location and the nature of the faulting process consequently research emphasis has been on local tectonics or those aspects of regional and global tectonics requiring high resolution i briefly describe below some of the highlights of these studies

a premonitory pattern of earthquakes in northern greece on 20 june 1978 at 20 h 03 min 23 s an earthquake of surface wave magnitude 6 5 occurred in the migdonian basin between the lagada and volvi lakes and 26 km from thessaloniki the main shock was preceded by a seismic sequence which started on 8 may the largest earthquake of that sequence occurred on 23 may and had a surface wave magnitude of 5 8 the long duration of this sequence before the main shock of 20 june had tremendous psychological effects on the whole country greek seismologists were in a difficult position during that time 8 may 20 june especially after the earthquake of 23 may when pressed to state whether these earthquakes were foreshocks or aftershocks long lasting seismic sequences with earthquakes of magnitude 6 are common in the aegean area because these sequences are sometimes followed by large earthquakes it is important to see whether the latter can be predicted the may june 1978 seismic sequence provided the opportunity for testing hypotheses about statistical properties which it has been suggested could distinguish between foreshocks and aftershocks this particular sequence has been investigated extensively1 4 and more accurate data are available than for any other sequence around greece focal mechanism studies5 6 and field observations2 showed that the largest earthquakes of the sequence were produced by horizontal extension in a nearly north south direction and that the main rupture occurred on a normal fault which strikes almost east west and dips to the north the fault length of the main shock of 20 june was estimated7 to be 32 km accurate determination of earthquake foci using portable seismographs showed that the earthquakes of this sequence were shallow h 17 km while the distribution of the epicentres had a very clear east west elongation4 5 a migration of the seismic activity from east to west has also been observed between 8 may and 14 july we investigate here the time variation of the average magnitude and the frequency of all the shocks with m 3 0 of this sequence the time variations of these seismic parameters are examined in connection with the distribution of well determined epicentres of 38 earthquakes with m 4 3 in order to search for any premonitory pattern of the 23 may and 20 june major earthquakes

shallow structure and recent evolution of the aegean sea a synthesis based on continuous reflection profiles abstract a dense grid of continuous seismic reflection profiles partly calibrated with drilling results has allowed construction of a structural outline of the entire aegean sea in the north aegean we observe a clear difference between the thickly sedimented northern margin basins and the steep slopes of the trough margin of the southern north aegean the trough itself comprises a series of separate tectonic depressions resulting from an apparent transtensional motion the central aegean consists of a complex tectonic puzzle caused by the prevailing extension incipient strike slip faulting sub parallel to the north aegean trough trend may however affect its eastern anatolian domain three main structural areas characterize the southern aegean comparable structural directions cut across this chiefly extensional basin but one fault system may be prevailing over the others depending on the area the central cretan sea results from the interaction of at least two distinct extensions these were superimposed on previous mostly e w structural trends generated during the inception of the southern hellenic subduction and led to the present day predominant sw ne trending extension as a hypothesis we propose that the overall late miocene present evolution of the aegean sea is directly dependent on two geodynamic processes to the southeast of the area collision between arabia and turkey leads to the lateral westward expulsion of the aegean continental crust and to the west hellenic subduction is still active

iterative deconvolution of teleseismic p waves from the thessaloniki n greece earthquake of june 20 1978 teleseismic long period p waves from the june 20 1978 thessaloniki n greece earthquake ms 6 4 were modeled in an attempt to extract information about asperities or barriers on the fault plane the analysis is based on the inversion method of complex p waves developed by kikuchi and kanamori 1982 a far field source time function with a rise time of 2 sec and a process time of 5 sec is inferred corresponding to a source dimension of about 10 km when a rupture velocity of 2 km sec is assumed

a source study of the thessaloniki northern greece 1978 earthquake sequence summary the thessaloniki northern greece earthquake sequence appears to have occurred along faults forming a graben structure this graben situated in the border region between the serbomacedonian massif and the vardar zone is bounded to the south west by clearly exposed north west striking north east dipping normal faults relative hypocentre determinations fault plane solutions surface faulting and the aftershock distribution suggest that some of these faults have been reactivated during the 1978 earthquakes the source parameters of the mainshock mb 6 1 ms 6 4 were determined by computing body wave synthetic seismograms in the time domain and comparing them with the observed this modelling constrained the orientation of faulting determined by the p wave fault plane solution it also constrained the source depth to 6 mp 2 km similar depths were calculated by a relative relocation method for the other three large events of the sequence the dislocation time function required for the far field had a total duration of 9 mp 1 5 s the body wave moment was 5 2 mp 1 8 times 1025 dyne cm for a fault length of 35 km and a fault width of 17 km both estimated from the aftershock distribution the static stress drop was found to be 4 bar an accelerograph record of the mainshock shows two distinct events 3 4 s apart these two events were unresolved by the long period data in the far field but the unusually long duration of the mainshock time function suggests an overall slow energy release which probably occurred as a sequence of events close in space and time seismic energy released in this fashion can account for waveform complexities observed at some stations

spatial variation in sediment fluxes redox conditions and productivity in the permian triassic panthalassic ocean abstract two permian triassic boundary sections in central japan provide a rare window into environmental conditions within the panthalassic ocean which encompassed more than half the earth s surface at 252 ma integration of petrographic geochemical and time series data provides new insights regarding the fluxes of major and trace components to the sediment as well as environmental conditions in both the deep and intermediate water masses at each study site the ubara section was located in a high productivity peri equatorial location whereas the gujo hachiman section was located in a moderate productivity location at some distance from the paleoequator an upward transition from gray organic poor cherts to black siliceous mudstones at both sites occurred in conjunction with increased primary productivity intensified euxinia within the oxygen minimum zone omz and decimation of the radiolarian zooplankton community euxinia in the omz of the equatorial panthalassic ocean developed episodically for a 200 250 kyr interval during the late permian followed by an abrupt intensification and lateral expansion of the omz around the permian triassic boundary throughout the study interval bottom waters at both sites remained mostly suboxic a finding that counters hypotheses of development of a superanoxic permo triassic deep ocean as a consequence of stagnation of oceanic overturning circulation

87sr 86sr stratigraphy from the early triassic of zal iran linking temperature to weathering rates and the tempo of ecosystem recovery recovery from the late permian mass extinction was slowed by continued environmental perturbations during the early triassic rapid fluctuations of the early triassic marine carbonate carbon isotope record indicate instability in the global carbon cycle and recent 18 o apatite studies link elevated temperatures to the prolonged biotic recovery high temperatures potentially caused enhanced continental weathering that was detrimental to marine ecosystems but linking weathering rates to temperature has proven difficult one proxy for weathering is the 87 sr 86 sr of marine carbonate we present here an 87 sr 86 sr record from an upper permian lower triassic succession near zal iran that is coupled to a 13 c carbonate record an increase in the rate of 87 sr 86 sr rise from the dienerian to the smithian may be linked to elevated continental weathering rates caused by warming during the smithian

the triassic timescale new constraints and a review of geochronological data a review of geochronological data underlying the geological time scale for the triassic yields a significantly different time scale calibration than that published in the most recent compi lation geologic time scale 2004 this is partly due to the availability of new radio isotopic data but mostly because strict selection criteria are applied and complications arising from biases both systematic and random are accounted for in this contribution the ages for the base and the top of the triassic are constrained by u pb ages to 252 3 and 201 5 ma respectively these dates also constrain the ages of major extinction events at the permian triassic and triassic jurassic bound aries and are statistically indistinguishable from ages obtained for the siberian traps and volcanic products from the central atlantic magmatic province respectively suggesting a causal link ages for these continental volcanics however are mostly from the k ar 40 ar 39 ar system which requires accounting and correcting for a systematic bias of c 1 between u pb and 40 ar 39 ar isotopic ages the 40 ar 39 ar ages being younger robust age constraints also exist for the induan olenekian boundary 251 2 ma and the early middle triassic olenekian anisian boundary 247 2 ma resulting in a surprisingly short dur ation of the early triassic which has implications for the timing of biotic recovery and major changes in ocean chemistry during this time furthermore the anisian ladinian boundary is con strained to 242 0 ma by new u pb and 40 ar 39 ar ages radio isotopic ages for the late triassic are scarce and the only reliable and biostratigraphically controlled age is from an upper carnian tuff dated to 230 9 ma yielding a duration of more than 35 ma for the late triassic all of these ages are from u pb analyses applied to zircons with uncertainties at the permil level or better the resulting compilation can only serve as a guideline and must be considered a snapshot resolving some of the issues mainly associated with inaccurate and misinterpreted data in previous publi cations however further advances will require revision of some of the data presented here

early triassic gulliver gastropods spatio temporal distribution and significance for biotic recovery after the end permian mass extinction a reduction in body size lilliput effect has been repeatedly proposed for many marine organisms in the aftermath of the permian triassic pt mass extinction specifically reduced maximum sizes of benthic marine invertebrates have been proposed for the entire early triassic this concept was originally based on observations on early triassic gastropods from the western usa basin and the dolomites n italy and it stimulated subsequent studies on other taxonomic groups however only a few studies have tested the validity of the lilliput effect in gastropods to determine whether the paucity of large sized gastropods is a genuine signal or the result of a poor fossil record and insufficient sampling in combination with a review of the literature we document numerous new abundant large sized gastropods from the griesbachian outcrops of greenland and from the smithian early spathian interval in the southwestern usa we show that large sized gulliver gastropods i were present soon after the pt mass extinction ii occurred in various basins sedimentary facies and environmental contexts from shallow to deeper settings and iii belong to diverse higher rank taxa focusing on the western usa basin we investigate areas from which microgastropod shell beds were previously presented as being typical however we show that gulliver gastropods do occur in the very same areas insufficient sampling effort is probably the main reason for the rarity of reports of large early triassic gastropods which is supported by preliminary rarefaction based simulations finally it appears that the recently documented middle to late smithian climate shifts and the severe end smithian extinction of nekto pelagic faunas did not reduce maximum shell sizes of gastropods