a paleoslope model of late albian to early turonian foraminifera of the western atlantic margin and north atlantic basin abstract a paleoslope model of albian to turonian benthic foraminifera reveals seven successive biofacies which are associated with increasing paleodepth the paleoslope model indicates that the biofacies occupied inner neritic to abyssal environments of deposition 10 m to 3500 m water depth biofacies 1 and 2 characterize paleodepths of less than 60 m the biofacies contain abundant species of epistomina and gavelinella and exhibit a rapid stratigraphic alternation in response to local sea level change which considerably aids in the identification of depositional sequences species of globorotalites eggerellina and neobulimina characterize biofacies 3 which principally occurs between 60 m and 130 m paleodepth biofacies 3 is the only biofacies to occur in both the new jersey coastal plain and the baltimore canyon trough biofacies 4 is composed of species of gavelinella gyroidinoides and valvulineria and is abundant in outer neritic to middle bathyal paleodepths of 130 m to 600 m it is largely replaced by biofacies 5 during times of maximum flooding during sea level rise a diverse assemblage of species of lingulogavelinella and lenticulina characterize biofacies 5 paleodepths of 600 m to greater than 3500 m contain abundant species of osangularia pleurostomella praebulimina pseudopatellinella and quadrimorphina which define biofacies 6 and 7 in addition four biofacies of much more limited distribution are recognized biofacies 1 characterizes shallow water open marine paleoenvironments of the north atlantic and is composed of spirillinids and species of epistomina turonian dysaerobic environments are indicated by biofacies dsa and dsb which are composed mostly of agglutinated species dysaerobic environments expanded rapidly from middle bathyal to outer neritic depths in the early turonian on the western atlantic margin biofacies daa represents disturbed benthic environments and is dominated by species of psammosphaera and reophax biostratigraphy and species composition of the studied biofacies are similar to previously described european and south atlantic assemblages major speciation events occur among the genera gavelinella lingulogavelinella and valvulineria well defined neritic and bathyal biofacies formed during a rapid late albian species diversification concomitant with the first major cretaceous flooding of continental margins

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

integrated upper carnian to lower norian biochronology and implications for the upper triassic magnetic polarity time scale abstract we summarize the ammonoid conodont and halobiid biochronology of the upper carnian to lower norian based on a discussion of data in the alps sicily balkans turkey himalayas and timor with this integrated biostratigraphic scale the pizzo mondello section sicily can be recalibrated and the carnian norian boundary more precisely located there as a result the magnetostratigraphy of this section is now in good agreement with previous results from turkey although the latter series are more condensed cross correlation of available magnetostratigraphic data from marine tethyan sections allow us to construct a composite upper carnian to upper norian geomagnetic polarity time scale gpts this gpts leads us to question previously proposed magnetobiostratigraphic and chronostratigraphic correlations within the upper triassic newark non marine sedimentary sequence

a model approach to radioactive waste disposal at sellafield one of the great environmental problems of our age is the safe disposal of radioactive waste for geological time periods britain is currently investigating a potential site for underground burial of waste near the sellafield nuclear plant future leakage of radionuclides depends greatly on subsurface water flows these must be understood from the past to predict hydrogeology 104 105 years into the future we have taken information from the present day published by the government company nirex and used a finite element steady state fluid flow computer code to examine water flows in the subsurface we find that flow directions at the planned repository are persistently upwards and that geologically significant flow rates could occur flow rates are particularly sensitive to uncertainties of rock permeability conductivity measurements made from site investigation boreholes the hydrogeology at this site needs longer term investigation before a confident and credible prediction can be made

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

chemical and isotopic characterization of water rock interactions in shales induced by the intrusion of a basaltic dike a natural analogue for radioactive waste disposal abstract disposal of nuclear waste in deep geological formations is expected to induce thermal fluxes for hundreds of years with maximum temperature reaching about 100 150 c in the nearfield argillaceous environment the long term behavior of clays subjected to such thermal gradients needs to be perfectly understood in safety assessment considerations in this respect a toarcian argillaceous unit thermally disturbed by the intrusion of a 1 1 m wide basaltic dike at the perthus pass herault france was studied in detail as a natural analogue the thermal imprint induced by the dike was evaluated by a mineralogical chemical and k ar study of the at the eastern contact with the dike the mineral and chemical compositions of both the shales and the basalt suggest water rock interactions subsequent to the intrusion with precipitation of palagonite and renewed but discrete deposition of carbonate a pencil cleavage developed in the shales during the dike emplacement probably favored water circulation along the contact strontium isotopic data suggest that the fluids of probable meteoric origin reacted with bathonian and bajocian limestones before entering the underlying toarcian shales by analogy with deep geological radioactive waste repositories the results report discrete mineralogical variations of the clays when subjected to temperatures of 100 150 c that are expected in deep storage conditions beyond 150 c significant mineralogical changes may alter the physical and chemical properties of the shales especially of the clay fraction also the development of structural discontinuities in the so called thermally disturbed zone might be of importance as these discontinuities might become zones for preferential fluid circulation finally the study emphasizes the use of rb sr and k ar isotopic systems as tracers of local circulating fluids related to low grade thermal imprints

middle upper triassic carbonate platforms in minorca balearic islands implications for western tethys correlations abstract in order to progress in the knowledge of the middle to upper triassic evolution of the western tethys realm an integrated approach which includes new sedimentological sequence stratigraphic and biostratigraphic data has been accomplished in the carbonate marine successions muschelkalk facies of that age in minorca balearic islands spain the new biostratigraphy which includes six successive ammonoid biozones allowed to assign these carbonate successions to the uppermost anisian lower carnian interval the integration of the new chronostratigraphic framework with the sedimentological analysis allowed to recognize five main successive stages of carbonate platform evolution 1 initial marine transgression and shallow ramp development uppermost anisian 2 carbonate ramp drowning anisian ladinian boundary 3 prevalence of open sea conditions ladinian early carnian 4 abrupt sea level drop intra lower carnian and 5 shallow carbonate ramp and transition to sabkha systems keuper facies furthermore the sequence stratigraphic analysis allowed to divide some of these stages into depositional sequences minorca was located in the westernmost tethys area during the triassic in a key paleogeographic location close to the present day iberia sardinia and the cottian and southern alps the new data have allowed an interregional comparative analysis among these areas with recognition of major suprarregional events and episodes in the framework of the western tethys evolution

carnian late triassic magnetostratigraphy from the germanic basin allowing global correlation of the mid carnian episode abstract the stuttgart formation traditionally called the schilfsandstein in the germanic basin or central european basin is a sand rich episode representing the mid carnian episode within the gypsum rich clayey semi arid keuper facies that regional mid carnian episode is now recognized to be a manifestation of a significant global disruption of earth s climate ocean biological system during the early late triassic in order to provide an accurate time frame and means for high resolution correlations among continental and marine records we obtained a composite magnetostratigraphy spanning the entire carnian from three boreholes in the germanic basin this composite shows a good consistency with earlier published magnetostratigraphy results from south china and enables the construction of a complete carnian polarity time scale the upper carnian tuvalian substage portion implies that 1 the lower quarter of the tuvalian is dominated by a reversed polarity magnetozone 2 the termination of the yangtze platform is coeval with deposition of the stuttgart formation in the germanic basin 3 the radiolarian rich green colored clay horizon of the pignola 2 section in south italy that is below a volcanic ash bed dated as ca 231 ma correlates with the d pulse of siliciclastics in dibona section of north italy in the middle of the tuvalian 4 the upper three fourths of the tuvalian is a major normal polarity dominated magnetozone and this interval correlates with the basal e1 e6 portion of the newark magnetic polarity reference series according to the favored correlation option 5 the base of the arnstadt formation of the germanic basin which had been traditionally assigned as the carnian norian boundary instead begins within the lower portion of newark reversed polarity zone e8r of earliest norian according to the favored age model although pending future verification 6 the polarity patterns of portions of the upper carnian from the western tethys sections of lower trench at silicka brezova in austria and pizzo mondello in italy are verified this carnian composite is an enhanced polarity time scale for calibration of other global carnian successions and events such as the appearance of the earliest dinosaurs in fossiliferous beds of south america

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

atlantic paleobathymetry paleoproductivity and paleocirculation in the late albian the benthic foraminiferal record spatial distribution patterns of benthic foraminifers in upper albian sediments from 25 dsdp odp sites and 31 onshore sections of the north and south atlantic ocean are used to generate paleobathymetric reconstructions and to identify areas of high primary production such as coastal and equatorial upwelling zones new paleobathymetric estimates are provided for dsdp odp sites and onshore locations that are not situated on oceanic crust paleobathymetric reconstructions indicate shallow water exchange between the north and south atlantic but show the existence of a deep water connection between the western and eastern tethys 2500 m through the gibraltar gateway strikingly there is no evidence for a strong latitudinal gradient in deep water benthic foraminiferal distribution during the late albian south atlantic assemblages show close affinity to north atlantic and tethyan assemblages exhibiting only a minor degree of provincialism biogeographic patterns reveal a distinct asymmetry in late albian paleoproductivity for the north atlantic as for the present day the eastern margins of the atlantic were generally more productive than the western margins and a belt of enhanced carbon aux export to the seafloor can be traced around the north african coast which probably corresponded to a zone of vigorous coastal upwelling by contrast assemblage composition in the south atlantic generally reflects mesotrophic to oligotrophic conditions benthic foraminiferal distribution patterns thus provide robust proxy data to test predictions from paleocirculation and paleobathymetric models for the mid cretaceous atlantic ocean and adjacent margins c 2001 elsevier science b v all rights reserved

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

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

unidirectional slip vectors in the western betic cordillera implications for the formation of the gibraltar arc we have investigated the kinematics of deformation in a sector of the gibraltar arc in sw spain by synthesizing lineation data from major faults the variation in structural trends and palaeomagnetically determined vertical axis rotations the kinematic data show that transport directions throughout formation of the arc were consistently wnw regardless of structural trend which varies between 050 and 350 in the study area the data suggest that this part of the gibraltar arc can be explained simply by oblique convergence with a curved indenter taken together with other published data it appears likely that the variation in thrust transport direction within the betic cordillera as a whole may be considerably less than that in the moroccan part of the arc unidirectional convergence combined with the presence of palaeomagnetic rotations implies either eycient overprinting of old rotated lineations and or a convergence rate that is much greater than the rotation rate also required is a low degree of partitioning in the thrust wedge the latter probably increases east of the study area where the structural trend becomes more oblique to the transport direction and major strike slip faults occur

from rifting to passive margin the examples of the red sea central atlantic and alpine tethys abstract evolution of the red sea gulf of suez and the central atlantic rift systems shows that an initial transtensive rifting phase affecting a broad area around the future zone of crustal separation was followed by a pre oceanic rifting phase during which extensional strain was concentrated on the axial rift zone this caused lateral graben systems to become inactive and they evolved into rift rim basins the transtensive phase of diffuse crustal extension is recognized in many intra continental rifts if controlling stress systems relax these rifts abort and develop into palaeorifts if controlling stress systems persist transtensive rift systems can enter the pre oceanic rifting stage during which the rift zone narrows and becomes asymmetric as a consequence of simple shear deformation at shallow crustal levels and pure shear deformation at lower crustal and mantle lithospheric levels preceding crustal separation extensional denudation of the lithospheric mantle is possible progressive lithospheric attenuation entails updoming of the asthenosphere and thermal doming of the rift shoulders their uplift provides a major clastic source for the rift basins and the lateral rift rim basins their stratigraphic record provides a sensitive tool for dating the rift shoulder uplift asymmetric rifting leads to the formation of asymmetric continental margins corresponding in a simple shear model to an upper plate and a conjugate lower plate margin as seen in the central atlantic passive margins of the united states and morocco this rifting model can be successfully applied to the analysis of the alpine tethys palaeo margins such as rif and the western alps

natural radioactivity and radioactive waste disposal abstract the disposal of long lived radioactive wastes by deep burial in suitable rock formations is an emotive issue although disposal is technically not exceptionally demanding the demonstration of long term safety using predictive hydrogeological and geochemical models has proved much more difficult in order to validate the results of such predictions the models and associated computer codes and databases are being tested and calibrated on natural radioactive systems this article looks at how information on natural radiation sources and the distribution and behaviour of radionuclides in geochemical systems is being used to evaluate the performance of deep radioactive waste repositories

wrenching in the external zone of the betic cordilleras southern spain abstract regional structural trends in the caravaca huescar area forming the central part of the external zone in the betic cordilleras indicate that deformation of the area results from right lateral wrenching subparallel to the paleogeographic zonation the structural trends do not fit the nappe interpretation generally used elsewhere in the external zone arguments for wrenching in the area are the structural inverse symmetry with respect to a central transcurrent fault zone the crevillente fault zone the distributional pattern of stratigraphic anomalies and types of deformation and the outcrop pattern of the paleogeographic zones it is argued that certain tectonic units in the area formerly interpreted as klippes in a nappe configuration form centers of flower structures and are vertically squeezed out blocks a theoretical model is sketched illustrating the evolution of a wrench zone under the stratigraphic conditions of the studied area and resulting in its present characteristics many of the features of the caravaca huescar area are also present elsewhere in the external zone and support the idea that wrenching was a major deformational mechanism it is therefore suggested that the external zone should in general not be described in terms of a nappe structure as has been done so far but in terms of a strike slip orogen or a wrenched continental margin

the role of extension in the miocene denudation of the nevado filabride complex betic cordillera se spain the internal zone of the betic cordillera se spain consists of a nappe stack of three complexes the deepest of which is the nevado filabride complex the zone is separated from the overlying alpujarride complex by a crustal scale shear zone that has variously been interpreted as a thrust or an extensional detachment a suite of 74 new apatite and zircon fission track results have been obtained from the nevado filabride complex and these have been used to define regional cooling patterns for the complex rapid cooling 105 c 200 c ma 1 is spatially related to the tectonic contact with the overlying alpujarride complex cooling to near surface temperatures occurred first in the east sierra de los filabres during the mid serravallian 12 1 ma and was completed by the early tortonian 9 8 ma in the west sierra nevada there is no correlation between fission track age and sample elevation these results are consistent with tectonic unroofing of this complex a finding that favors extension as the mechanism by which the two complexes were brought into contact extension spans the middle and earliest upper miocene 12 8 ma in the study area and therefore lasted much longer than previously documented a hypothesis is advanced which links oblique convergence between the iberian plate and the betic internal zones resulting in crustal contraction at depth with orogen parallel extension in the middle and upper crust

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

platform to shelf edge transect triassic of northern israel north arabian plate abstract a transect of the middle to late triassic from the epicontinental belt to the shelf edge of the north arabian margin is presented based on new data from two boreholes in northern israel two sedimentary systems are encountered along this traverse the inland meged 2 borehole represents the seaward extension of the epicontinental belt with shallow to deep water carbonates salina evaporites and basinal shales while ga ash 2 on the levant margin was positioned on an isolated platform separating the internal shelf basin system from the open tethys displaying a shallower range of facies that is free of evaporites proximal distal facies shifts are bundled into five low order lo t r cycles ranging from anisian pelsonian to norian each composed of numerous high order ho shallowing upwards cycles meged 2 paleoenvironments imply an interior basin trapping sediments of the epicontinental belt with numerous ho facies shifts indicating pulses of subsidence ga ash 2 contains lofer like peritidal cycles and a late anisian early carnian hiatus in place of the second lo cycle the two orders of cycling are controlled by extrabasinal regional or eustatic change and synsedimentary vertical movements the divergent sedimentary patterns of the late anisian late carnian can be attributed to nw se trans tensile movements impacting on earlier neotethyan extensional trends synsedimentary movements represented locally by uplift at ga ash 2 and subsidence at meged 2 controlled the influx of sea water into the epicontinental zone and consequently controlled the alternation of evaporite vs carbonate systems in the latest carnian early norian these facies belts become locked together forming a shallow high energy shelf this change reflects broad uplift and shifting of the locus of active differential movement into the levant basin

quantitative analysis of calcareous microfossils across the albian cenomanian boundary oceanic anoxic event at dsdp site 547 north atlantic nannofossil and planktonic and benthic foraminiferal assemblages were studied quantitatively in an expanded albian to cenomanian section at dsdp site 547 in the eastern north atlantic the section spans a 0 5 positive 13c excursion across the albian cenomanian boundary representing one of the mid cretaceous oceanic anoxic events oae1d the base of the carbon excursion at site 547 coincides with a major faunal turnover in planktonic foraminifera including extinctions and first appearances of several species as well as geographic entries in contrast nannofossil assemblage composition which reflects conditions in the photic zone shows little variation related to the carbon excursion arguing against a noticeable change in surface water productivity during the event benthic foraminifera which represent a paleowaterdepth of around 1 km show that there was no change in environmental conditions at that water depth and offer no support for increased deep water anoxia combined with published data microfossils at site 547 suggest that improved preservation of organic matter due to a decrease in oxygen content in a shallow oxygen minimum zone is a more likely cause for the albian cenomanian boundary anoxic event than an increase in productivity

the geologist s dilemma predicting the future behaviour of buried radioactive wastes the last 10 15 years have produced a considerable amount of research into the geological disposal of radioactive wastes this has had some very beneficial spin offs for the geosciences there are however a number of areas where it is difficult for earth scientists to provide quantitative information required for the types of long term safety assessment being performed at present with the likely increased stringency with which we may begin to treat other industrial wastes much is to be learned from the radioactive waste experience this article reviews some of the geological issues in constraining long term predictions discusses how geological data are used and questions exactly what it is that we are trying to achieve in the management of these wastes and in the regulations concerning their disposal

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

phosphorus and the roles of productivity and nutrient recycling during oceanic anoxic event 2 four sections documenting the impact of the late cenomanian oceanic anoxic event oae 2 were studied in basins with different paleoenvironmental regimes accumulation rates of phosphorus p bound to iron organic matter and authigenic phosphate are shown to rise and arrive at a distinct maximum at the onset of oae 2 with an associated increase in 13 c values accumulation rates of p return to preexcursion values in the interval where the 13 c record reaches its fi rst maximum an offset in time between the maximum in p accumulation and peaks in organic carbon burial hydrogen indices and corg preact molar ratios is explained by the evolution of oae 2 in the following steps 1 an increase in productivity increased the fl ux of organic matter and p into the sediments the preservation of organic matter was low and its oxidation released p which was predominantly mineralized 2 enhanced productivity and oxidation of organic matter created dysoxic bottom waters the preservation potential for organic matter increased whereas the sediment retention potential for p decreased 3 the latter effect sustained high primary productivity which led to an increase in the abundance of free oxygen in the ocean and atmosphere system after the sequestration of co 2 in the form of black shales this oxygen helped push the ocean back into equilibrium terminating black shale deposition and removing bioavailable p from the water column

cycle calibrated magnetostratigraphy of middle carnian from south china implications for late triassic time scale and termination of the yangtze platform abstract thick successions from the margins of the triassic yangtze platform of the south china block record a transition from carbonate rich facies zhuganpo formation and equivalents to clastic rich facies xiaowa formation and equivalents during the carnian early late triassic that mark the final phase of termination of this long lived platform cyclostratigraphy derived from spectral gamma ray sgr intensity curves was combined with magnetostratigraphy of two sections in guizhou province wayao transect and its upward extension into the geopark wayao in guanling county and the laishike section in zhenfeng county and one location in sichuan province hanwang section the cyclostratigraphy from all the guizhou sections indicates a persistent suite of ca 34 m 9 m and 1 8 m cycles which are consistent with the ratios of orbital climate oscillations caused by long eccentricity 405 kyr short eccentricity 100 kyr and precession 20 kyr the magnetostratigraphy of all sections is consistent with the cyclicity and characteristic sgr features thereby enabling a cycle tuned magnetic polarity scale spanning 2 4 myr the main feature is a 1 3 myr interval of reversed polarity containing brief normal polarity subchrons and this reversed polarity chron appears to correspond to the significant reversed polarity dominated interval spanning the upper half of the trachyceras aonoides through the lower half of the austrotrachyceras austriacum ammonoid zones of the upper julian the lower substage of carnian this magnetostratigraphic correlation implies that the termination of the yangtze platform is coeval with the beginning of the mid carnian episode of climatic disruption in europe which is locally called the carnian pluvial event or wet intermezzo and with the temporary cessation of the platform carbonates in the dolomites the cycle scaled magnetic polarity time scale supports the short tuvalian long norian age model of the late triassic in which the base of the cycle tuned polarity pattern from the newark group of eastern north america is younger than the end of the julian substage

paleomagnetic rotations and the kinematics of the gibraltar arc paleomagnetic investigations of a mesozoic limestone sequence around the gibraltar arc show that there have been large systematic rotations about a vertical axis and imply that there must have been a significant component of westward motion within the betic rif orogenic belt rotations of the late jurassic and late cretaceous limestones in the betic cordillera of southern spain are clockwise with the exception of the unrotated sierra gorda whereas the jurassic sites in the rif mountains of morocco are rotated counterclockwise except in the area around tetuan these data are generally consistent with formation of the arc either by a westward moving alboran microplate or by extensional collapse of a collisional mountain chain the former model however fails to recognize the nonrigid nonplate like character of the alboran domain and lacks a definable driving mechanism a model of a collapsing east west elongated ridge that takes into account the obliquity of the convergence along the active margin may provide mechanisms both for the observed rotations and for the large westward component of motion and therefore can explain the geometry of the gibraltar are

mathematical modelling of groundwater flow at sellafield uk abstract sellafield in west cumbria was a potential site for the location of the uk s first underground repository for radioactive intermediate level waste ilw the repository was to lie around 650 m beneath the ground surface within rocks of the borrowdale volcanic group bvg a thick suite of sw dipping fractured folded and metamorphosed ordovician meta andesites and ignimbrites these are overlain by an onlapping sequence of carboniferous and permo triassic sediments in situ borehole measurements showed that upward trending fluid pressure gradients exist in the area of the potential repository site and that there are three distinct fluid types in the subsurface fresh saline and brine at depth to the west of the site simulations of fluid flow in the sellafield region were undertaken with a 2d steady state coupled fluid and heat flow simulation code oilgen in both simplified and geologically complex models topographically driven flow dominated the regional hydrogeology fluids trended persistently upwards through the potential repository site the dense brine to the west of the site promoted upward deflection of topographically driven groundwaters the inclusion in hydrogeological models of faults and variably saline sub surface fluids was essential to the accurate reproduction of regional hydraulic head variations sensitivity analyses of geological variables showed that the rate of groundwater flow through the potential repository site was dependent upon the hydraulic conductivity of the bvg and was unaffected by the hydraulic conductivity of other hydrostratigraphic units calibration of the model was achieved by matching simulated subsurface pressures to those measured in situ simulations performed with bvg hydraulic conductivity 100 times the base case median value provided the best fit comparison between the calculated equivalent freshwater head and that measured in situ regardless of the hydraulic conductivity of other hydrostratigraphic units transient mass transport simulations utilising the hydraulic conductivities of this best fit simulation showed that fluids passing through the potential repository site could reach the surface in 15 000 years simple safety case implications drawn from the results of the study showed that the measured bvg hydraulic conductivity must be less than 0 03 m year 1 to be simply declared safe recent bvg hydraulic conductivity measurements showed that the maximum bvg hydraulic conductivity is around 1000 times this safety limit

lower to middle triassic sequence stratigraphy and climatology of the netherlands a model abstract the biostratigraphic framework for the triassic used by the nederlands aarddolie maatschappij in the netherlands has been reviewed and update this resulted in the recognition of 5 palynological zones and 8 subzones northwest european palynological assemblages have been interpreted in terms of xerophytic and hygrophytic flora elements characterising dry and humid climatic conditions the biostratigraphic zonation the climatic fluctuations both in the northwest european basin and on the northwestern margin of the tethys and the cyclic lithostratigraphical development have been integrated this leads to a climatological sequence stratigraphical model for the lower middle triassic of the netherlands during the late scythian smithian early spathian monsoonal activity was responsible for the activation of an ephemeral drainage system on the northern side of the central european highland under the influence of sealevel highstands the position of the monsoon belt shifted northwards and the northward flowing drainage system was most active leading to mass transport of erosional products from the highlands into the germanic basin based on a combination of biostratigraphic data and climatic events the lower triassic sedimentary cycles in the netherlands can be linked indirectly with the standard sequence stratigraphy and to milankovitch orbitally forced cyclicity for the marine middle triassic sediments a more direct link is envisaged

sequence stratigraphic framework of the german triassic abstract the sequence stratigraphic methodology can be readily applied to the cratonic basin fill of the classic german triassic consisting of shallow marine to terrestrial mixed carbonate siliclastic rocks the whole triassic succession represents a second order transgression regression cycle built by third order depositional sequences systems tracts and parasequences many bounding surfaces represent widely used marker beds long used in classical lithostratigraphy using a synthesis of outcrop well log and literature data on stratal geometry facies cycle stacking patterns and paleogeography a regional chart of coastal onlap was constructed within the limitations of the presently available biostratigraphic data the observed cycles appear to correlate fairly well with those in other areas but include a number of additional sequences not included in the haq et al 1988 chart comparative analysis of regional onlap curves from different globally spread triassic basins together with an improved biostratigraphy will be necessary to relate the accommodation changes to eustatic versus tectonic and climatic controls and to produce a refined eustatic chart the german basin could provide a favourable reference point for such an analysis

record of the carnian wet episode in strata of the chinle group western usa the late triassic carnian wet episode was an interval of humid climate evident in the lowermost strata of the upper triassic chinle group in the western usa chinle deposition began with the development of major river systems of the shinarump formation and equivalents laterally equivalent to and or overlain by floodplain deposits containing kaolinitic gleyed to spodic palaeosols and local coal beds the chinle strata immediately above these wet episode strata are deposits of smaller rivers that lack coal or carbonaceous strata and contain non kaolinitic palaeosols that are locally calcareous and vertic indicative of drier but strongly seasonal climates the lowermost chinle strata contain fossil tetrapods palynomorphs and conchostracans that are consistent with other data that indicate that the basal chinle strata are of julian age and immediately overlying lower chinle strata are early tuvalian so these strata are the age of the carnian wet episode identification of a long norian stage places the norian base in the chinle group near the top of the strata of the wet episode which means that norian strata sit directly on early carnian strata but there is no unconformity at this level to support recognition of such a long norian in the chinle section

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

role of strike slip faults in the betic rifian orogeny abstract a new model for the betic rifian orogeny of the western mediterranean spain and north africa is proposed in which four strike slip faults play an important role the faults are not of the same age two faults the left lateral jebha fault to the south in morocco and principally in the mediterranean sea and the right lateral north betic fault southern spain to the north define the boundaries of the alboran block betic and rifian internal zones final movement along these faults was during the burdigalian time two other faults the left lateral nekor fault north africa to the south of the jebha fault and the right lateral crevillente fault somewhat to the north of the north betic fault define a larger alboran block including part of the betic and rifian external zones that was present during the tortonian the following sequence of events is proposed 1 a during the eocene and oligocene the african and european plates converged in a n s sense causing the breakup and overthrusting of the betic rifian and kabyle internal zones and then the movement towards the wsw of the alboran block by slip along the jebha and north betic faults 2 b by the end of burdigalian time movement along the jebha and north betic faults ceased 3 c with continued n s convergence the nekor and crevillente faults which bound a larger alboran block were formed during the mid and late miocene the arc of gibraltar the zone lying between the four major faults seems to be a result of wsw motion of a crustal block being thrust over external zones the model proposed adds to the earlier idea that tectogenesis proceeds from the interior to the exterior of an erogenic belt in the betic rifian orogeny major strike slip fracture zones shifted to the exterior of the orogenic belt as the orogeny progressed in order to relieve the stress caused by locking of the more internal faults

mid cretaceous paleogeography and paleoceanography of the betic seaway betic cordillera spain abstract sedimentary and micropaleontological features of cretaceous formations in the betic seaway have been examined in the external zone of the betic cordillera southern spain planktic and benthic foraminiferal assemblages were studied to establish a biostratigraphic framework and to provide estimates of paleo waterdepth further environmental interpretations are based on the analysis of clay minerals sedimentary petrography and organic geochemistry we suggest the existence of several subbasins with differing subsidence histories created by transform tectonics along the axis of the betic seaway a comparison with mid cretaceous sequences of adjacent dsdp odp holes indicates that the general paleoceanographic conditions within the seaway were similar to the north atlantic our results are integrated in a paleogeographic reconstruction for the western mediterranean during the late albian

the biostratigraphic importance of conchostracans in the continental triassic of the northern hemisphere conchostracans or clam shrimp order conchostraca sars are arthropods with a carapace consisting of two chitinous lateral valves triassic conchostracans range in size from 2 to 12 5 mm long and are common in deposits that formed in fresh water lakes isolated ponds and brackish areas their dessication and freeze resistant eggs can be dispersed by wind over long distances therefore many conchostracan species are distributed throughout the entire north ern hemisphere in the late permian to middle triassic interval several of these forms are also found in gondwana many wide ranging conchostracan species have short stratigraphic ranges making them excellent guide forms for subdivision of triassic time and for long range correlations the stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits this makes con chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits upper triassic gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere in the norian some slight provincialism can be observed even within the northern hemisphere for example the sevatian redondestheria seems to be restricted to north america and acadiestheriella n gen so far has been found only in the sevatian deposits from the fundy basin of southeastern canada here we establish a con chostracan zonation for the changhsingian late permian to hettangian early jurassic of the northernhemispherethat forthemostpart isverywellcorrelatedwiththemarinescale thiszona tion is especially robust for the changhsingian to early anisian late ladinian to cordevolian and rhaetian to hettangian intervals for most of the middle and upper triassic this zonation is still preliminary five new genera six new species and a new subspecies of conchostracans are described that are stratigraphically important half of the eight stage boundaries of the triassic have been defined by a bio event within a marine global stratotype and point gssp locality and these definitions have been accepted by both the international subcommission on triassic stratigra phy and the international commission on stratigra phy the remaining four stage boundaries are nearing final definition in the lower triassic both the base of the induan priority brahmanian stage base of triassic and the base of the next younger olenekian stage have been firmly defined in the middle triassic there is wide agree ment that the defining species for the base of the anisian stage should be chiosella timorensis in the gssp candidate site at desli caira romania but there has not yet been a formal vote on this the base of the overlying ladinian stage however has been firmly defined in the upper triassic the base of the carnian has been firmly likewise defined but there is not yet a final defi nition for the boundaries of the overlying norian and rhaetian stages a consensus has not been reached on a defining species for the base of the norian or its gssp locality but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval for the base of the rhaetian misikella posthernsteini kozur mock has been chosen as the defining species by the international working group on the rhaetian stage and the gssp candidate locality at steinbergkogel austria has been studied in detail by a group under the leadership of l krystyn vienna and presented to the participants of the international conference on upper triassic sub divisions zonations and events in bad goisern in the autumn of 2008 the base of the overlying hettangian stage base of the jurassic has been defined so far only by a working group as the fad first appearance datum of psiloceras spelae guex taylor rakus bucher the final definition of the triassic stages within marine gssp sections will be completed in the near future but more than 50 of known triassic rocks are of continental origin therefore the main task of triassic stratigraphers in thefuture will besubdivid ing and correlating terrestrial strata both between

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

carbonate facies of the upper triassic ojo huelos member san pedro arroyo formation chinle group southern new mexico paleoclimatic implications abstract the upper triassic adamanian lvf ojo huelos member of the san pedro arroyo formation chinle group is a distinctive carbonate rich unit that occurs in the lower chinle section of central new mexico the member consists mainly of micritic lime mudstones ostracodal wackestones to grainstones peloidal grainstones and distinctive pisolitic rudstones interbedded with fine grained siliciclastic mudstones most limestones exhibit some evidence of pedogenic brecciation and root penetration and porous fabrics similar to those of modern limestone tufas occur locally the interbedded mudstones are typically lenticular and commonly display a blocky ped fabric in which subequant peds are separated by sparry calcite veins fossils from the ojo huelos member are freshwater darwinulid ostracodes various freshwater fishes and aquatic amphibious tetrapods metoposaurs and phytosaurs we interpret the carbonate facies as the deposits of carbonate lakes ponds and wetlands that were partly spring fed whereas the interbedded and surrounding mudstones were alluvial in origin the groundwater and overland hydrology of the region was likely controlled by the relative proximity to an upland recharge area in the mogollon highlands to the south but sedimentary fabrics record strong overprinting by desiccation and pedogenic reworking consequently we interpret the ojo huelos member as recording a climate that varied from subhumid to semi arid which caused episodic falls in the hydrologic base level this resulted in landscape degradation exemplified by significant pedogenic and erosional reworking of the carbonate sediments and fluvial incision

provenance of the lunz formation carnian in the western carpathians slovakia heavy mineral study and in situ la icp ms u pb detrital zircon dating abstract the middle carnian julian detritic sediments of the lunz formation were deposited during of the so called carnian pluvial event they are the only siliciclastic sediments embedded in purely carbonatic formations the paper brings the first provenance analysis of this formation from the western carpathians slovakia where it occurs in the hronic fatric and veporic zones sandstones of the lunz formation belong to feldspatic greywackes and less to lithic greywackes modal analyses indicate that the sand material was derived from dissected arc and less from a recycled orogen the heavy mineral assemblage is dominated by zircon and by apatite slightly lesser amount of garnet cr spinels and tourmaline analysis of tourmalines schorl and dravite shows their primary provenance mainly from the metapelites and metapsammites coexisting or not coexisting with an al saturating phase some were also derived from fe3 rich quartz tourmaline rocks calc silicate rocks and metapelites and a slightly smaller group of grains was derived from li poor granitoid rocks and their associated pegmatites and aplites most of the garnet grains belong to almandine less to spessartine all of them have a wide spectrum of potential primary source rocks from low to medium grade metamorphic rocks and magmatites the analysed spinel grains cr rich spinel chromite and magnesiochromite match mostly the podiform chromitites harzburgite and cumulate fields or supra subduction zone peridotites field whereas al depleted spinel best match the arc volcanic field some spinels were affected by alteration or metamorphism the in situ la icp ms isotopic u pb dating shows a wide age interval of detrital zircon crystals in the lunz formation concordant zircon data show a wide interval of late triassic carnian to early proterozoic ages 230 2500 ma majority of zircons shows paleozoic pre variscan and variscan ages whereas neoproterozoic to paleoproterozoic age populations are relatively scarce age populations and chemical composition of zircon reveal their dominant primary provenance from various suites of magmatic rocks including variscan granitic rocks and pre variscan metaigneous lithologies characteristic is big scatter in zircon ages and the dominance of ultrastable minerals as zircon tourmaline rutile and cr spinels and quite a good correlation between zircons and cr spinels this indicates that most of the heavy minerals were not directly derived from some distinct primary magmatic or metamorphic sources but as recycled particles from older sediments or metasediments in the context with the previously published palaeogeographic reconstructions the provenance analysis indicates that the source area was most likely situated outside the alpine carpathian shelf they are most likely related to the coeval mostly fluvial stuttgart formation in the central european basin germanic triassic basin

a multidisciplinary biofacies characterisation of the late triassic late carnian rhaetian kapp toscana group on hopen arctic norway abstract a multidisciplinary study of the kapp toscana group de geerdalen flatsalen and svenskoya formations on hopen svalbard provides an enhanced palaeoenvironmental interpretation for the upper triassic succession on the island the biofacies of the formations were characterised using a combination of palynological palynofacies and micropalaeontological analyses micropalaeontological palynofacies and 13corg data are presented from hopen for the first time six distinct biofacies assemblages were recognised i lower undifferentiated de geerdalen formation characterised by a dominance of fern spores and low abundance assemblages of foraminifera and ostracods interpreted to reflect deposition in a deltaic environment during maximum marine regression ii upper de geerdalen formation hopen member rich in bisaccate gymnosperm pollen and the alga plaesiodictyon mosellaneum consistent with deposition in a brackish marginal marine setting iii lower flatsalen formation characterised by microforaminiferal linings marine phytoplankton and super abundant agglutinated foraminifera considered to reflect deposition in a shallow marine environment iv middle flatsalen formation dominated by dinoflagellate cysts radiolaria and ostracods indicating deposition in a relatively distal dysoxic anoxic marine environment a maximum flooding surface is inferred based on the acme of radiolarians and dominance of dinoflagellate cysts v upper flatsalen formation corresponding to a decrease in marine palynomorphs absence of radiolaria agglutinated foraminifera and ostracods and an increase in terrestrial organic matter and vi svenskoya formation characterised by a dominance of terrestrial palynomorphs and deposited in a fluvio deltaic environment the biofacies units are integrated with the established litho chrono and palynostratigraphic framework for the island and contribute to an enhanced palaeogeographic understanding of the barents sea region during the late triassic

isotope palaeohydrology and the prediction of long term repository behaviour there are considerable well recognized difficulties involved in the investigation of very low permeability rocks by conventional measurements of water potentials and spatial distribution of hydrological parameters such as permeability and effective porosity therefore most studies of predictive behaviour are based on models which when unconstrained by data are often worse than no model at all geochemistry and environmental isotope geochemistry are techniques well suited for hydrological investigations of potential sites of nuclear waste isolation and for constraining predictive models stable isotopes constitutive of the water molecule 2h and 18o may give information on the origin of the water especially 2h which is practically uninvolved in isotope exchange with rock forming minerals variations in stable isotope contents can be related to palaeohydrological and palaeoclimatic conditions whereas 3h is indicative of recent recharge the 13c content of dissolved carbon is related to its origin s and the 14c activity gives a time scale however the initial carbon isotope contents can be modified by various diagenetic effects such as precipitation dissolution of secondary calcite and oxidation of reduced carbon the heavy isotope content of the total dissolved inorganic carbon tdic cannot be interpreted without a detailed knowledge of the carbon chemistry and of the mineralogy and isotope contents of secondary carbonates species of dissolved organic carbon doc with high molecular weights hmw can generally be attributed to soil derived compounds their 14c content may be measured by ams accelerator mass spectrometry thus providing an estimate of the time elapsed since recharge took place chlorine 36 is an interesting potential tool for dating old ground waters because of its long half life 301 kyr and its hydrophilic behaviour it can be also produced in situ in significant amount if the rocks are rich some tens of ppm in u and th in such cases this time dependent build up provides a more systematic radiochronometer of ci residence time in the rock than the decay of cosmic input 36ci provided no cl is leached from the rock the isotopic composition of aqueous sulphur compounds depends on their origin and on their diagenetic evolution the redox reactions of so2 4 reduction or of s2 oxidation are marked by strong isotope effects especially when generated by bacteria sulphate reduction by organic matter is a potential source of dissolved inorganic carbon and may thus interfere with 14c age interpretations after discussion of the possible age and origin of waters and solutes some scenarios of evolution of local and regional palaeohydrological conditions are proposed examples are given with special emphasis on detailed results from the fennoscanian shield stripa project and from northern switzerland

argillization processes at the el berrocal analogue granitic system spain mineralogy isotopic study and implications for the performance assessment of radwaste geological disposal abstract the el berrocal granite u bearing quartz vein uqv system has been studied as a natural analogue of a high level radioactive waste repository the main objective was to understand the geochemical behaviour of natural nuclides under different physicochemical conditions within this framework the argillization processes related to fracturing and formation of the uranium quartz vein were studied from a mineralogical and isotopic standpoint in order to establish their temperatures of formation and thus complete the geothermal history of the system for this purpose 18 o values were determined for pure mineral from the unaltered granite and quartz from the uranium quartz vein as well as for mixture samples from the hydrothermally altered granite sericitised granite and clayey samples from fracture fillings including the clayey walls of the uranium quartz vein the isotopic signature of quartz from the uranium quartz vein and the monophasic nature of its fluid inclusions led us to conclude that the isotopic signature of water in equilibrium with quartz was approximately in the range from 8 3 to 5 7 v smov its temperature of formation being around 85 120 c the 18 o values of pure sericite from the hydrothermally altered granite calculated by means of the oxygen fraction molar method indicate that its temperature of formation in equilibrium with the aforementioned waters is also in the range from 70 c to approximately 120 c clays from fracture fillings and clayey walls of the uranium quartz vein are usually mixtures in different proportions of illite approximately formed between 70 and 125 c two generations of kaolinite formed at approximately 90 130 c and at around 25 c respectively smectite formed at 25 c and occasionally palygorskite formed either between 30 and 45 c or 19 and 32 c depending on the fractionation equation used these data suggest that sericite from the hydrothermally altered granite quartz from the uranium quartz vein illite and the first generation of kaolinite from the fracture fillings resulted from the same hydrothermal process affecting the el berrocal granite in relation to fracturing under certain physicochemical conditions t 100 c ph 8 and log h 4 sio 4 between 4 and 3 illite and kaolinite can be paragenetic as a result of weathering processes smectite was formed from hydrothermal illite and inherited albite under alkaline weathering while the second generation of kaolinite was formed from smectite under acid conditions and close to the sulphide rich uranium quartz vein palygorskite is an occasional mineral formed probably either during the thermal tail of the above described hydrothermal process or during weathering processes in both cases palygorskite must have formed from alkaline si mg rich solutions finally these data and processes are discussed in terms of natural analogue processes drawing some implications for the performance assessment of a deep geological radwaste repository dgrr

iberian plate motions during the mesozoic abstract as more data are collected on the deep parts of the conjugate margins of canada and eurasia models of the early kinematics of iberia become better constrained in order to specify the motions during phases of continental rifting to the west and to the north of iberia we used recent data on the early oceanic spreading in the tagus abyssal plain and added simple assumptions on the geometry the tagus abyssal plain was formed after the end of continental rifting on the southwest portuguese margin in latest jurassic time before chron m 0 118 ma as a first step we close the space adjacent to the m 0 anomaly to keep open only the oldest oceanic part of the tagus plain which is assumed to be latest jurassic to earliest cretaceous in age in a second step we close this space the main results are as follows 1 1 the galicia bank slid along the southern flank of flemish cap this motion is interpreted as a strike slip motion or as a very oblique rifting 2 2 a late jurassic reconstruction of iberia and north america is obtained without considerable overlap and without large motion of microplates such as galicia bank this is possible because a large amount of continental extension occurred over a long time to the north of the grand banks and permitted early motion between north america and eurasia 3 3 a tight initial reconstruction can only be reached if strike slip motion is located between southern eurasia and northern eurasia along a shear zone following the english channel and the transform area between galicia bank and flemish cap

sea level fall carbonate production rainy days how do they relate insight from triassic carbonate platforms western tethys southern alps italy the interplay of sea level fall climate and sedimentological changes is recorded across two sequence boundaries at the top of two triassic carbonate platform systems in the western tethys earliest carnian and norian rhaetian boundary in age paleolatitude 18 25 n the sea level falls caused subaerial exposure of the platform top and decreased carbonate production leading to starvation in the intraplatform basins followed by deposition of shale evidence of freshwater input indicates that the change in sedimentation was driven by increased rainfall on the previously arid european hinterland and tethys coast a uniformitarian approach holocene sea level changes and global warming are coupled with changes in the distribution of precipitation implicates global cooling as the probable cause of the observed sea level climate and sedimentological changes global cooling likely triggered the sea level fall by increased storage of fresh water in continental settings and change in seawater density probably coupled with ephemeral ice sheet development possible even during greenhouse intervals such as the triassic furthermore global cooling caused a shift toward the equator of the poleward boundary of the arid belt this model is supported by the traceability of the sequence boundaries and climate sensitive facies from the tethys shelf up to the european continent the observed association of global climate changes sea level fall sedimentological changes and shift toward humid climate documents how climate sensitive facies record the control exerted by global changes on local sedimentation

fold trends and stress deviation in the alicante fold belt southeastern spain abstract palaeostress orientations derived from analysis of stylolites and small scale faults can be correlated with plate movements however stress deflections up to the kilometre scale occur at large scale faults the regional fold trend in the eastern pre betic alicante region is east northeast which is characteristic of the betic cordilleras in the southern part of the alicante region an anomalous n s fold trend dominates biostratigraphic data and regional structural analysis show no clear difference in the age of the two fold trends although dome and basin structures suggest overprinting the n s folds are interpreted as en echelon folds in a right lateral wrench zone palaeostress analysis supports this interpretation the e w compression which caused the n s folds is a local fault related deviation of the regional betic nw se compression

neotectonic evolution of the central betic cordilleras southern spain abstract paleostress orientations were calculated from fault slip data of 36 sites located along a traverse through the central betic cordilleras southern spain heterogeneous fault sets which are frequent in the area have been divided into homogeneous subsets by cross cutting relationships observed in the field and by a paleostress stratigraphy approach applied on each individual fault population the state of stress was sorted according to main tectonic events and a new chronology is presented of the miocene to recent deformation in the central part of the betic cordilleras the deviatoric stress tensors fall into four distinct groups that are regionally consistent and correlate with three late oligocene aquitanian to recent major tectonic events in the betic cordilleras the new chronology of the neotectonic evolution includes from oldest to youngest the following main tectonic phases 1 late oligocene aquitanian to early tortonian 1 subhorizontal n s partly e w directed 3 subvertical compressional structures thrusting of nappes large scale folding and strike slip faulting in the alboran domain and the external zone of the betic cordilleras 2 early tortonian to pliocene pleistocene 1 subvertical 3 subhorizontal nw se partly n s directed or e w directed radial extension large scale normal faulting in the central betic cordilleras and in the oldest neogene formations of the granada basin related to the gravitational collapse of the betic cordilleras and the exhumation of the intensely metamorphosed rock series of the internal zones at the same time formation of the alboran basin and intramontane basins such as the granada basin 3 pleistocene to recent 3a 1 subvertical 3 subhorizontal ne sw with prominent normal faulting but coevally 3b 1 subhorizontal nw directed 3 ne sw subhorizontal with strike slip faulting extensional structures and strike slip faulting are related to the ongoing convergence of the eurasian and african plates and coeval uplift of the betic cordilleras reactivation of pre existing fractures and faults was frequently observed phase 3 is interpreted as periodic strike slip and normal faulting events due to a permutation of the principal stress axes mainly 1 and 2

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

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

sedimentology clay mineralogy and palaeosols of the mid carnian pluvial episode in eastern spain insights into humidity and sea level variations this study examines rainfall variations of the mid carnian pluvial episode cpe based on the continental fluvial sedimentology palaeosol and clay mineralogy records of the stable meseta e spain in the formation examined manuel fm or k2 fm the cpe is represented by three regressive transgressive sequences r t or subunits k2 1 k2 2 and k2 3 from base to top each subunit broadly consists of a genetic stratigraphic sequence bearing well developed highstand lowstand and transgressive system tracts hst lst and tst hydromorphic features in the palaeosols suggest changes in the activity of both ground and surface waters the clay mineral assemblage is dominated by illite with a minor presence of kaolinite and traces of smectite in some samples after ruling out tectonism in the study area climate and eustatism emerge as the main allogenic controls in the sedimentary record differentiated sedimentary facies and architectural elements in the k2 2 subunit were likely controlled by both a more humid climate and source area while k2 1 and k2 3 were more related to base level changes and eustatic control the presence of more waterlogged pedotypes and of kaolinite and traces of smectite in the clay mineral assemblage of k2 2 also indicates increased humidity notwithstanding our data do not point to intense rainfall periods for the cpe in e spain

active faulting and neotectonics in the baelo claudia area campo de gibraltar southern spain abstract the strait of gibraltar area is part of the western eurasian african convergence zone characterized by a complex pattern of deformation including thrusting and folding and active normal faulting generally the area is of low seismicity only some minor earthquakes have been recorded in the last hundred years archaeoseismological data evidences earthquake destruction occurring twice during roman times a better neotectonic framework and knowledge on the paleostress evolution of the strait of gibraltar area is necessary to find the local sources for those events and to establish an understanding of the recent deformation paleoseismic evidence for one moderate earthquake event around 6000 5000 bp along the normal carrizales fault is described in this paper off shore high resolution seismic investigations structural and paleostress data high resolution gpr and geoelectrical resistivity measurements outcrop investigations and trenching studies are discussed the data reveal that active faulting takes place along n s trending normal faults hence n s directed normal faults in the area are claimed as local candidates for moderate earthquake activity return periods of moderate earthquakes in the order of at least 2000 2500 years in the study area may have to be taken into account structural data such a paleostress data and joints are presented and a deformation history for the strait of gibraltar area in southern spain is developed in this study

development of asymmetric basins along continental transform faults abstract many basins associated with wrench or transform faults are asymmetrical both longitudinally and laterally the sense of basin asymmetry changes along the strike of transform faults geophysical data from the dead sea rift and other transforms indicate that wrench induced asymmetric basins are bounded on only one side by a transform fault this implies that during the evolution of such basins maximum compression was parallel to the transform the direction of extension can change during the geologic evolution of a basin a possible explanation of this observation takes the strength of the fault into into consideration in the case of a weak fault in a strong crust the horizontal principal stresses would probably rotate to orientations parallel and perpendicular to the fault thus minimizing the shear stress on the main fault basins formed by regional extension such as in the east african rift system sometimes show similar features recent studies have shown that these basins often undergo oblique extension this suggests that the asymmetry in these basins may result from simultaneous strike slip motion and fault normal extension similar to the way asymmetry is produced in large transform basins periods of oblique extension can alternate with periods of orthogonal extension the asymmetry formed during periods of oblique extension is often preserved in the stratigraphic record

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

alpine tectonics and rotation pole evolution of iberia abstract the geological evolution of the betic cordilleras and pyrenees reflects the cretaceous and tertiary rotation pole and kinematic evolution of the iberian and african plates new constraints on the alpine tectonic evolution of the iberian plate are provided by p t t data and regionally consistent stretching lineations from the metamorphic parts of the betic cordilleras high pressure low temperature metamorphism in the betic cordilleras resulted from continent continent collision which caused subduction to a maximum depth of 37 km a preliminary 116 10 ma radiometric age for this event corresponds to the initiation of seafloor spreading to the west of iberia which lasted until about 80 ma intracontinental thrusting in the betics between 99 ma and 83 ma took place after subduction ended e w to ese wnw trending stretching lineations indicate the direction of thrusting which resulted in extensional strains of 200 600 the timing of thrusting in the betics coincides with a 95 80 ma tectonic phase in northern africa during which e w stretching lineations were formed the stretching lineations are coincident with the 110 80 ma motion vector of africa iberia with respect to eurasia thrusting in the betics and deformation in northern africa was driven by convergence of africa iberia and eurasia cretaceous deformation is further recorded by terrigeneous sedimentation in the mauritanian flysch and by the tectosedimentary evolution of the malaguide complex crustal thinning magmatism and metamorphism in the pyrenees during the 110 85 ma period is governed by a left lateral strike slip of africa iberia with respect to eurasia around the same rotation pole as thrusting in the betics during the 80 54 ma period the rotation pole was situated west of gibraltar near the previous active collision zone this inhibited large scale overthrusting and related penetrative deformation in northern africa and the betic cordilleras deformation was instead transferred to the northern boundary of iberia now acting as an african promontory from the campanian on wards oblique convergence took place around the combined gibraltar rotation pole deformation culminated in the late eocene corresponding to spreading in the norwegian greenland sea at 55 ma which induced an additional compression in western eurasia during the pyrenean collision high pressure metamorphic rocks in the betic cordilleras were exhumed and they cooled substantially the cooling trend was disturbed by oligocene extensional deformation and introduction of a transient heat source which correlates with the mantle being uplifted during extension heating culminated at the oligocene miocene boundary in the betic cordilleras and in northern africa this evolution agrees with the development of a plate boundary between iberia and africa at 30 ma after completion of the pyrenean collision the new plate boundary was connected to the western european rift system renewal of compression and overthrusting in the betic zone took place after 20 ma overthrusting is succeeded by two phases of wrenching juxtaposing crustal segments with different moho depths inherited from the late oligocene to early miocene extension

structure and kinematics of the south iberian paleomargin and its relationship with the flysch trough units extensional tectonics within the gibraltar arc fold and thrust belt western betics abstract the superposition of structures observed in a selected area of the external zones of the betic orogen situated in the westernmost segment of the peri mediterranean mountain belt reveals an alternation of compressional and extensional events during the overall convergence of the african and eurasian plates that bound the system an early miocene compressional event produced the formation of the so called gibraltar arc fold and thrust belt formed by the units derived from the south iberian paleomargin and the flysch trough this wedge constitutes the footwall of the gibraltar thrust whose hanging wall corresponds to the alboran domain the outward migration of the compressional front w to nwward in the south iberian segment was followed by the outward migration of the extensional locus related to the middle miocene rifting that led to the alboran basin subsidence the tectonic inversion of the gibraltar thrust was accompanied by normal faulting of the innermost part of the paleomargin and the flysch trough units finally the alboran region underwent n s to nw se compression from late miocene onwards which caused the uplift of the gibraltar arc area

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