tectonic evolution of a part of the tethyside orogenic collage the kargi massif northern turkey the central part of the rhodope pontide fragment one of the major tectonic units in turkey provides critical data for evaluating the cimmeride and alpide evolution of the mediterranean tethysides tectonic events that affected the central part of the rhodope pontide fragment since the end of the paleozoic generated east west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes this evolution may be conveniently described in terms of three major episodes 1 two different realms of pre dogger oceanic rocks are present in the area the northern realm coincided with main branch of paleo tethys that was being actively destroyed by south dipping subduction the southern realm the karakaya ocean a back arc basin related to this subduction began opening by rifting of a retroarc carbonate platform during the permo triassic to the west a continental domain with sparse magmatism seperated the two oceanic areas toward the east the two oceans become united by the wedging out of the continental domain these two pre dogger oceans closed during the lias and their remnants were emplaced between the southern margin of laurasia and the fragments of the cimmerian continent 2 the second episode partly overlapped the first with rifting south of the cimmerian continent fragment during the lias this rifting was followed by a transgression which covered the ruins of the cimmeride orogenic belt by the malm this rifting concurrently led to the development of the northern branch of the neo tethys and a south facing atlantic type continental margin a southerly thickening sedimentary prism developed on this margin during the lias to early cretaceous interval 3 the floor of the northern branch of neo tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin this convergent margin generated a magmatic arc to the north and to the south a subduction accretion complex present width of which approaches 80 km to the south of the subduction accretion complex yet another convergent margin is indicated by the presence of the remnants of an ensimatic arc the northern branch of the neo tethys was totally consumed in the late cretaceous to eocene interval

the lost paleosols masked evidence for emergence and soil formation on the kimmeridgian jura platform nw switzerland abstract lagoonal carbonates of kimmeridgian age in nw switzerland formed in a tropical epeiric sea and exhibit indicators of subaerial emergence such as tidal biolaminites desiccation cracks flat pebble conglomerates and fenestral structures additionally 30 dinosaur tracksites from at least six stratigraphic intervals indicate repeated formation of land bridges between the platform and adjacent massifs populations of herbivorous and carnivorous dinosaurs necessitate substantial vegetation and consequently a soil cover but no striking evidence of paleosols have been found within the track bearing sequences however two stratigraphic levels exposed in nine outcrops exhibit distinctive hardgrounds that experienced early meteoric diagenesis during times of emergence initial induration began with the precipitation of thin micritic meniscus cements contemporaneously meteoric waters completely dissolved all aragonite leaving large voids iron hydroxides were precipitated in the uppermost 7 10 cm where they impregnated the porous micrite and constituted a separate cement generation which caused a penetrative dark red staining these aspects are suggestive of the formation of mediterranean type red soils on the emerged platform during transgression the soil was eroded and wave cut hardgrounds were superimposed on the hardgrounds formed during regression erosion is evidenced by micro karst truncated gastrochaenolites isp borings and the physical removal of steinkerns the eroded material including floral remains provided surplus nutrients leading to eutrophication this food rich environment supported the mass occurrence of gastropods in the nerineoid limestones and oysters nanogyra sp in the virgula marls

southward migration of arc magmatism during latest cretaceous associated with slab steepening east pontides n turkey new paleomagnetic data from the amasya region abstract a new paleomagnetic study was carried out on the findikli formation in the amasya region which is to the north of the ankara erzincan neotethyan suture zone in order to better understand the paleogeographic evolution of the pontides tectonic belt during the maastrichtian samples were collected from volcanoclastic sandstones and lavas at 51 sites rock magnetic experiments identified pseudo single domain psd titanomagnetite as the main magnetic carriers at the majority of sites progressive thermal and alternating demagnetization revealed that the characteristic remanent component is removed between 400 and 580 c or 20 100 mt respectively a high temperature component which indicates the presence of titano hematite is found only in some lavas declinations show a systematic dispersion across the study area related to tectonic rotations about vertical axes inclinations are consistent however and yield a mean paleolatitude of 20 0 n 2 5 for the maastrichtian comparison of the results from this study with the reference direction of the east pontides from the turonian campanian is best explained with a model involving slab roll back and marginal basin formation between 90 and 65 ma period

carbon and oxygen isotope records of palaeoenvironmental and carbonate production changes in shallow marine carbonates kimmeridgian swiss jura carbon and oxygen isotope ratios are commonly used to correlate shallow and deep marine successions carbon and oxygen isotope analyses were performed on bulk carbonate samples from two kimmeridgian sections of the swiss jura platform in order to correlate them with biostratigraphically well dated coeval sections in the adjacent basin on the platform a general decrease in 13 c and 18 o values from the base to the top of the studied interval is measured whereas time equivalent pelagic hemipelagic carbonates record an increase in carbon and oxygen isotope ratios moreover the measured 13 c and 18 o values are generally lower than those indicated for the kimmeridgian open ocean and show high frequency variations superimposed on the general trend samples were screened for diagenetic alteration using optical and cathodoluminescence petrography and coupled carbon and oxygen isotope and trace element analyses some observations favour a role for diagenetic alteration but isotopic and elemental trends as well as sedimentological evidence suggest that the more negative values of 13 c and 18 o relative to kimmeridgian seawater are also due to local environmental conditions high frequency changes in 18 o and 13 c values most likely result from variations in salinity and carbonate production and accumulation rates these variations were produced by different water masses that were isolated from the open ocean and developed their own geochemical signatures repeated isolation was induced by high frequency sea level fluctuations and helped by irregular platform morphology consequently carbon and oxygen isotope records in shallow marine carbonates can be used for stratigraphic correlation only if their origin is well known

middle cretaceous calcareous nannofossil biogeography and preservation in the atlantic and indian oceans implications for paleoceanography abstract the quantitative study of calcareous nannofossil preservation and biogeographic distribution puts constraints on paleoceanographic models for the atlantic and indian oceans during the middle cretaceous we establish a dissolution ranking of middle cretaceous calcareous nannofossils based on susceptibility to dissolution a positive correlation of organic carbon content of the sediments and the relative abundance of watznaueria indicates that much of the carbonate dissolution was caused by the release of carbon dioxide during oxidation of organic matter the depth distribution of the most dissolution resistant species watznaueria barnesae shows relative abundance maxima at the deepest sites and a maximum where intermediate waters impinge on slopes this reflects stagnant oxygen poor bottom waters and possibly a mid water oxygen minimum zone with increased deposition and catabolic breakdown of organic matter factor analyses are performed on various data sets for three different time slices ranging in age from late aptian to early albian middle albian and late albian to cenomanian the resulting factors can be related to paleoceanographic conditions such as colder water at high latitudes high fertility upwelling conditions and neritic conditions for all three time intervals a wide tropical to subtropical zone was flanked by boreal and austral zones upwelling conditions probably existed along the north african margin and over the falkland plateau zonal upwelling is tentatively postulated for the northwestern and northeastern margin of the north atlantic in the middle albian and for the eastern margin of the north atlantic off western europe for the late albian to cenomanian we speculate on surface water current patterns location of upwelling regions and haline driven deep circulation for the middle cretaceous

extension tectonics in the wessex basin southern england the permian to cretaceous tectonic evolution of the wessex basin was controlled by horizontal tensional and vertical isostatic forces within the lithosphere the gross morphologies of its constituent structures were governed by the location of variscan thrust and wrench faults in the upper and middle crust which suffered extensional reactivation in tensional stress fields oriented approximately nw se several episodes of crustal extension can be resolved in early permian early triassic early jurassic and late jurassic early cretaceous times these were characterized by the rapid subsidence of fault bounded basins and commonly by erosion of adjacent upfaulted blocks superimposed upon the fault controlled subsidence dominant during periods of fault quiescence and becoming increasingly important with time a component of regional subsidence is considered to have a thermal origin this suggests that crustal extension was accompanied by some form of not necessarily uniform lithospheric thinning subsidence analyses assuming local airey isostasy give cumulative crustal extension factors of 20 28 beneath the grabens a more reasonable assumption of regional airey compensation indicates basinwide crustal extension of 13 17 which is consistent with birps offshore deep seismic reflection data

the indian monsoon and its variability for over 300 years the monsoon has been viewed as a gigantic land sea breeze it is shown in this paper that satellite and conventional observations support an alternative hypothesis which considers the monsoon as a manifestation of seasonal migration of the intertropical convergence zone itcz with the focus on the indian monsoon the mean seasonal pattern is described and why it is difficult to simulate it is discussed some facets of the intraseasonal variation such as active weak cycles break monsoon and a special feature of intraseasonal variation over the region namely poleward propagations of the itcz at intervals of 2 6 weeks are considered vertical moist stability is shown to be a key parameter in the variation of monthly convection over ocean and land as well as poleward propagations special features of the bay of bengal and the monsoon brought out by observations during a national observational experiment in 1999 are briefly described

petrogenesis of the late cretaceous demirkoy igneous complex in the nw turkey implications for magma genesis in the strandja zone abstract the srednogorie zone in bulgaria and its eastern continuation in nw turkey the strandja zone consist of a late cretaceous magmatic belt comprised of plutonic volcanic and associated volcano sedimentary rocks the demirkoy igneous complex is the biggest cretaceous pluton within the strandja zone and its age is between 71 and 84 ma the demirkoy pluton and additional smaller plutons are intruded into triassic and older metamorphic basement rocks a contact metamorphic aureole with hornblende hornfels facies conditions was developed around the demirkoy pluton the wnw trending demirkoy pluton has an elliptical shape and a concentrically zoned internal structure in this structure gabbro diorites and quartz diorites are only seen in the sw corner of the pluton while granodiorites form the main body of the pluton surrounded by a zone of granite the granodiorites contain dioritic mafic microgranular enclaves small quartz monzonite lenses and or bodies and mafic dykes are also observed in the demirkoy igneous complex geochemically the demirkoy igneous complex has calc alkaline metaluminous and medium k characteristics there is a significant correlation between the lree hree ratios and sio 2 values chondrite normalized ree patterns are relatively flat la n lu n 2 in gabbros this ratio ranges from 3 to 11 for the diorite granodiorites and from 14 to 35 for the granites dioritic enclaves have ree patterns similar to those of the main body and have la n lu n values between 3 and 6 relatively enriched lile sr k rb ba and th and relatively depleted hfse ta nb and ti values indicate the classic subduction related origin of the complex the initial isotopic signatures range from e nd i 0 45 to 2 57 and 87 sr 86 sr i 0 7042 0 7064 for gabbros and e nd i 0 43 to 2 67 and 87 sr 86 sr i 0 7048 0 7059 for granodiorites and granites 18 o values range from 6 18 to 7 80 vsmow for gabbros and from 6 86 to 8 89 vsmow for granodiorites and granites based on geochemical and isotopic characteristics this magmatic complex can be subdivided into 4 groups a gabbro b diorite to alkali granite main body c syenite monzonite and d mafic dykes geochemical data and modelling results favour a typical subduction related enriched lithospheric mantle and lower crustal source for the demirkoy igneous complex slab derived fluids and crustal contamination also played a key role in the petrogenesis of this magmatic suite

inferred palaeoproterozoic arc rifting along a consuming plate margin insights from the stratigraphy volcanology and geochemistry of the kangerluluk sequence southeast greenland the 200 to 300 m thick volcano sedimentary sequence in the kangerluluk fjord associated with penecontemporaneous and late tectonic dykes as well as a synvolcanic plutonic suite represents an integral component of the palaeoproterozoic ketilidian mobile belt south greenland the ca 1808 ma kangerluluk supracrustal sequence contains four distinct mappable lithofacies a a conglomerate sandstone lithofacies b a pyroclastic lithofacies c a volcanic lithofacies and d a peperite lithofacies the volcanic lithofacies up to 200 m thick is characterized by shallow water subaqueous brecciated and pillowed flows flows are either a feldspar phyric or b feldspar pyroxene phyric with 0 2 to 3 cm size plagioclase and 0 2 to 3 cm size pyroxene that constitute between 20 and 30 locally up to 50 of the flows mafic dykes intruded wet unconsolidated pyroclastic lithofacies resulting in the formation of peperites geochemically the volcanic and pyroclastic units represent a distinct tholeiitic magmatic suite enriched in incompatible trace elements including th la yb zr and nb and exhibiting la yb n 10 the plutonic suite and associated dykes display a calc alkaline trend with enriched lree and unfractionated flat hree patterns lan ranging between 50 and 100 la yb n ratios between 8 and 22 and negative nb and ti anomalies on the mantle normalized incompatible multi element patterns the pillowed flows lie in the continental flood basalt field on the y nb zr discrimination diagram and display a nb anomaly and k2o enrichment that collectively suggest a crustal component and or a subduction modified mantle source the geology stratigraphy of the kangerluluk area and geochemistry can be used to infer a change in magma genesis from arc to rift volcanism the 1850 to 1800 ma calc alkaline julianehab batholith represents a magmatic arc that rifted during crustal extension allowing for the ascent of mantle derived mafic magma the geochemistry of the mafic volcanic flows synvolcanic dykes and pyroclastic deposits favours a crustal component in magma genesis and offers new insights into the tectonic evolution of the ketilidian mobile belt

platform to basin correlation by high resolution sequence stratigraphy and cyclostratigraphy berriasian switzerland and france based on detailed analyses of facies evolution and stacking pattern of berriasian carbonate dominated sections in the swiss jura mountains the swiss ultrahelvetic and the french vocontian trough a high resolution platform to basin correlation is proposed biostratigraphical tie points are furnished by ammonites dinoflagellates calpionellids and ostracod charophyte assemblages the hierarchical stacking of small scale depositional sequences reflects milankovitch cyclicity sequences corresponding to the 20 100 and locally 400 ka orbital cycles can be identified elementary 20 ka sequences on the platform generally consist of one bed of shallow subtidal to intertidal high or low energy carbonate facies whereas on the slope and in the basin they are commonly developed as limestone marl couplets these elementary sequences group into small scale composite sequences reflecting the first orbital eccentricity cycle 100 ka which in turn build up large scale 3rd order composite sequences one 3rd order sequence has been analysed in detail according to the cyclostratigraphic interpretation it took 2 myr to form which is in accordance with the duration of the corresponding ammonite subzones sequence stratigraphic and cyclostratigraphic platform to basin correlation shows that for about 900 ka the platform was exposed or only partly flooded whereas on the slope and in the basin lowstand deposits with channel fills and slumps accumulated with rising sea level accommodation space gradually increased on the platform and a thickening upward sequential pattern with transgressive facies developed while in the basin the facies still had lowstand characteristics with thick and nodular limestone beds this situation lasted about 700 ka the following 300 ka were characterized by sediment starvation and increased bioturbation on the platform and by more marly transgressive sediments on the slope and in the basin the maximum flooding phase is more or less isochronous on the platform and in the basin although the surface with the best developed maximum flooding features may be displaced by one or two small scale composite sequences because of superimposed high frequency sea level fluctuations and or local variations in substrate morphology and sediment distribution third order highstand conditions prevailed for only about 100 ka the combination of cyclostratigraphy and high resolution sequence stratigraphy constrained by good biostratigraphy is thus a powerful tool for detailed stratigraphical correlation over long distances and from one sedimentary environment to another

cretaceous anoxic oxic changes in the moldavids carpathians romania abstract this study focused on the cretaceous black shale successions followed by red shales that crop out at the outer regions of the romanian carpathians in the moldavids the oldest parts of the black shale units deposited in an abyssal plain during late valanginian late barremian time they are mainly characterized by hemipelagic and pelagic muddy siliciclastic rocks and carbonates commonly intercalated with fine grained turbidites during the sedimentation of the middle part of the black shale units in the late barremian early albian interval the depth of the basin increased as the carbonate hemipelagic sedimentation was replaced by a mainly siliceous one only a few thin turbidite intercalations are present the youngest part albian pro parte of the black shale units is characterized by a turbiditic sedimentation with mainly sandy sequences of middle and lower deep water fans we may assume that the depth of the basin continuously decreased the presence of authigenic glauconite in the albian sandstones suggests a palaeoenvironmental change linked to the occurrence of oxygenated turbidity current circulation a significant shift in the sedimentation regime in the eastern carpathian moldavids took place in the late albian when cretaceous oceanic red beds corb occurred this type of sedimentation lasted up to the coniacian the lower part of the corbs that contains radiolarites intercalated with variegated shales pyroclastic tuffs and thin sandstones is interpreted as a hemipelagic and pelagic sedimentation in the abyssal plain environment where rarely turbidites occurred upwards there are mainly burrowed variegated red and green shales the youngest parts of corbs are characterized by increased thickness and frequency of the turbidites while the main part of the corb is carbonate free or has very low carbonate content the upper part of these strata becomes rich in marl and mudstone strata indicating a decrease of the basin depth the accumulation of black shales in the eastern carpathians during the late valanginian late albian interval is linked to the existence of a small silled basin of the moldavian trough in which restricted circulation led to the density stratification of the water column resulting in the deposition of anoxic lower cretaceous sediments i e the black shales because of the tectonic deformation that took place within the lower upper cretaceous boundary interval the restricted circulation had changed to an open circulation regime in the moldavian trough hence the anoxic regime was progressively replaced by an oxic one across the albian cenomanian boundary interval the beginning and the end of the corbs in the moldavid units depend thus on various palaeogeographic and palaeoenvironmental settings and it was controlled by the regional tectonic activity

quartz silt in mudrocks as a key to sequence stratigraphy kimmeridge clay formation late jurassic wessex basin uk sequence stratigraphic interpretation of mudrocks is often carried out using proxy indicators for grain size or by consideration of other aspects of lithology thought to relate to sea level change such as organic matter content an alternative stratigraphic analysis based on direct estimation of quartz silt content was carried out on a major late jurassic mudrock and oil source rock the kimmeridge clay formation of the wessex basin dorset uk the new data generated by backscatter sem x ray and image analysis show decametrescale stratigraphic patterns that are incompatible with many previous sequence stratigraphic interpretations based on gamma ray logs or visual lithofacies and biofacies description correlation with a basin margin section in the boulonnais northern france indicates that silt rich intervals in basinal facies are coeval within the limits of biostratigraphic resolution with shallow water sand rich packages on the margin variation in silt content in the kimmeridge clay therefore appears to be a record of relative sea level change of at least regional extent it is suggested that analysis of silt content offers the most reliable basis for generation of a regional sequence stratigraphy in basinal mudrocks a revised relative sea level curve for the wessex basin kimmeridgian and early tithonian is presented based on this premise

effects of lithospheric in plane stress on sedimentary basin stratigraphy in plane lithospheric stress though known to exist has generally been ignored in the quantitative modeling of basin stratigraphy however low levels of intraplate lateral stress can induce observable plate deformations 10 100 m of vertical motion if the lithosphere contains a preexisting deformation such as a sedimentary basin the importance of in plane stress in modifying the stratigraphy of a sedimentary basin has been assessed using an elastic plate model for the lithosphere a compressive in plane stress generally induces basin subsidence with peripheral uplift shoreline regression while a tensile in plane stress induces basin uplift and peripheral subsidence shoreline transgression these simple results are complicated by variations in crustal thickness as now two interfaces are involved that is the sediment basement interface of the sedimentary basin and the moho topography the isostatic state of a sedimentary basin therefore ultimately controls the resultant deformation induced by in plane stress the implications of in plane stress modification of basin stratigraphy are profound regionally correlatable transgressions and regressions of basin interiors e g cyclothems and passive continental margins the third order variations of the vail et al 1977a coastal onlap curve may be tectonically produced by the interaction of stress induced base level changes and a basin tectonic driving subsidence in plane stress its generation magnitude and variation is considered a consequence of plate boundary reconfigurations during continental collisions rifting and subduction obduction

cenozoic evolution of the eastern black sea a test of depth dependent stretching models abstract subsidence analysis of the eastern black sea basin suggests that the stratigraphy of this deep extensional basin can be explained by a predominantly pure shear stretching history a strain rate inversion method that assumes pure shear extension obtains good fits between observed and predicted stratigraphy a relatively pure shear strain distribution is also obtained when a strain rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form the timing of opening of the eastern black sea which occupied a back arc position during the closure of the tethys ocean has also been a subject of intense debate competing theories called for basin opening during the jurassic cretaceous or paleocene eocene our work suggests that extension likely continued into the early cenozoic in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism further basin deepening also appears to have occurred in the last 20 myr this anomalous subsidence event is focused in the northern part of the basin and reaches its peak at 15 10 ma we suggest that this comparatively localized shortening is associated with the northward movement of the arabian plate we also explore the effects of paleowater depth and elastic thickness on the results these parameters are controversial particularly for deep water basins and margins but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy

the black sea basins structure and history new model based on new deep penetration regional seismic data part 2 tectonic history and paleogeography abstract a new lithostratigraphy scheme has been compiled for the western black sea basin and a new geological history scheme from middle jurassic till neogene is suggested for the entire black sea region continental rifting manifested itself from the late barremian to the albian while the time of opening of the basins with oceanic crust was from cenomanian till mid santonian origination of the western and eastern black sea basins took place almost simultaneously during cenozoic time numerous compressional and transpressional structures were formed in different part of the black sea basins it is shown that in pleistocene quaternary time turbidities mass transport deposits and leveed channels were being formed in the distal part of the danube delta

relative sea level change climate and sequence boundaries insights from the kimmeridgian to berriasian platform carbonates of mount saleve e france the present study analyses the stratal architecture of the late jurassic kimmeridgian to early cretaceous berriasian sedimentary succession of mount saleve e france and four berriasian stratigraphic intervals containing four sequence boundary zones reflecting lowering trends of the relative sea level evolution massive kimmeridgian limestones characterized by the presence of colonial corals appear to be stacked in an aggrading pattern these non bedded thick deposits which are interpreted to have formed in balance between relative sea level rise and carbonate accumulation suggest a keep up transgressive system above well bedded tithonian to berriasian peritidal carbonates reflect a general loss of accommodation these strata are interpreted as a highstand normal regressive unit during the early phase of this major normal regression the vertical repetition of upper intertidal lower supratidal lithofacies indicates an aggrading depositional system this is in agreement with an early stage of a highstand phase of relative sea level the berriasian sequence boundary zones investigated up to 4 m thick developed under different climatic conditions and correspond to higher frequency forced and normal regressive stages of relative sea level changes according to the classical sequence stratigraphic principles these sequence boundary zones comprise more than one candidate surface for a sequence boundary three sequence boundary zones studied in early berriasian rocks lack coarse siliciclastic grains contain a calcrete crust as well as marly levels with higher abundances of illite with respect to kaolinite and exhibit fossilized algal microbial laminites with desiccation polygons these sedimentary features are consistent with more arid conditions a sequence boundary zone interpreted for the late berriasian corresponds to a coal horizon the strata above and below this coal contain abundant quartz and marly intervals with a higher kaolinite content when compared to the illite content accordingly this late berriasian sequence boundary zone was formed under a more humid climate the major transgressive regressive cycle of relative sea level identified and the climate change from more arid to more humid conditions recognized during the late berriasian have been reported also from other european basins therefore the kimmeridgian to berriasian carbonate succession of mount saleve reflects major oceanographic and climatic changes affecting the northern margin of the alpine tethys ocean and thus constitutes a reliable comparative example for the analysis of other coeval sedimentary records in addition the stratigraphic intervals including sequence boundary zones characterized in this study constitute potential outcrop analogues for sequence boundary reflectors mapped on seismic profiles of subsurface peritidal carbonate successions the detailed sedimentological analyses provided here highlight that on occasions the classical principles of sequence stratigraphy developed on seismic data are difficult to apply in outcrop a sequence boundary reflector when seen in outcrop may present successive subaerial exposure surfaces which formed due to high frequency sea level changes that were superimposed on the longer term trend of relative sea level fall

cyclostratigraphy orbital tuning and inferred productivity for the type kimmeridge clay late jurassic southern england three independently measured variables magnetic susceptibility photoelectric factor and total gamma ray obtained from throughout the type kimmeridge clay fm in dorset southern england were used to identify regular metre scale sedimentary cycles spectral analysis demonstrates that for long stratigraphical intervals the cycles are expressed as large amplitude cycles of 1 87 4 05 m wavelength and smaller amplitude cycles of around half that wavelength these cycles are interpreted to record orbital obliquity and precession respectively the much larger amplitude of the inferred obliquity cycles compared with the precession cycles may indicate a high latitude climatic forcing transferred to lower latitudes via sea level variations orbital tuning indicates that the early kimmeridgian sensu anglico lasted at least 3 6 ma 95 longer wavelength cycles and the late kimmeridgian at least 3 9 ma 103 longer wavelength cycles the first detailed productivity estimates for the kimmeridge clay fm on a cycle by cycle calculation indicate that average productivity of the type kimmeridge clay 220 g m 2 a 1 was less than the average productivity on modern continental shelves the high average organic carbon content of the type kimmeridge clay 3 8 total organic carbon cannot be attributed to high average productivity however the average organic carbon content is consistent with low siliciclastic mineral dilution of organic matter and or elevated preservation linked to reduced bottom water oxygenation

a miocene island arc volcanic seamount the takashibiyama formation shimane peninsula sw japan abstract the miocene volcanic complex of the takashibiyama formation consists largely of subalkali subaqueous basalt to andesite lavas and andesite to dacite subaqueous volcaniclastic flow deposits most of subaqueous lavas are moderately to intensely brecciated with rugged rough surfaces and ramp structures similar to subaerial block lava volcaniclastic flow deposits commonly include basalt to andesite lava fragments and or pyroclastic materials and are similar in internal features to debris flow and turbidite deposits subaqueous block lavas and minor pillow lavas form volcanic piles above the vents being flanked or covered with volcaniclastic flow deposits each volcanic pile is several kilometers wide and several hundred meters thick and overlaps one after another as the major eruptive center migrates from time to time thus the volcanic complex comprises three or more superimposed volcanic piles which are intruded by basalt to andesite dikes and sills and are underlain by mafic to intermediate large hypabyssal to plutonic bodies hydrothermal alteration occurs in places but especially concentrates in the lower part of the volcanic complex after the cessation of opening of the japan sea the volcanic complex started to erupt in a middle bathyal environment on the japan sea side and became emergent as it grew to a thickness over 1500 m during 4 m y under a n s trending horizontal compressional stress it is a volcanic seamount probably in a typical island arc setting

a mesozoic time scale we present an integrated geomagnetic polarity and stratigraphic time scale for the triassic jurassic and cretaceous periods of the mesozoic era with age estimates and uncertainty limits for stage boundaries the time scale uses a suite of 324 radiomenc dates including high resolution 40 ar 39 ar age estimates this framework involves the observed ties between 1 radiometric dates biozones and stage boundaries and 2 between biozones and magnetic reversals on the seafloor and in sediments interpolation techniques include maximum likelihood estimation smoothing cubic spline fitting and magnetochronology

dating of the black sea basin new nannoplankton ages from its inverted margin in the central pontides turkey the eocene uplift and inversion of a part of the black sea margin in the central pontides allows to study the stratigraphic sequence of the western black sea basin the revision of this sequence with 164 nannoplankton ages indicates that subsidence and rifting started in the upper barremian and accelerated during the aptian the rifting of the western black sea basin lasted about 40 myr from late barremian to coniacian in the inner inverted black sea margin the syn rift sequence ends up with shallow marine sands the uppermost albian to turonian was a period of erosion or non deposition this regional mid cretaceous stratigraphical gap might result from rift flank uplift as expected in the case of a thick and cold pre rift lithosphere however coeval collision of the kargi block along the north tethyan subduction zone at the southern margin of the pontides might also have contributed to this uplift a rapid thermal post rift subsidence of the margin occurred during the coniacian santonian collision of the kirsehir continental block commenced in early eocene time zone np12 giving rise to compressional deformation and sedimentation in piggyback basins in the central pontides whereas the eastern black sea was still opening

sequence analytical approach to the upper kimmeridgian lower tithonian storm dominated ramp deposits of the boulonnais northern france a landward time equivalent to offshore marine source rocks an interdisciplinary approach based on high resolution physical stratigraphy biostratigraphy organic matter analysis and clay mineralogy has been applied to the mixed siliciclastic carbonate kimmeridgian tithonian deposits of the boulonnais north western france these rocks are the age equivalents of some of the offshore marine source rocks of the north sea and were deposited in an overall storm dominated homoclinal ramp setting which may represent one of the most shore proximal sediments of this age cropping out in north western europe comparison with data from the yorkshire dorset lorraine and aquitaine areas allows the discrimination of three major transgressive regressive sediment packages with disconformities of interregional extent 1 from the baylei zone to top eudoxus zone 2 from the autissiodorensis zone to base scitulus zone 3 from the upper scitulus zone to the pectinatus zone the lower two regionally correlative disconformities correspond to the sequence boundaries at the top of the eudoxus zone and the top of the autissiodorensis zone formed by high frequency relative sea level variations during the periods of maximum transgression of the platform the latter disconformity the p1 nodule bed reflects a major tectonically induced reorganization of the north west european intrashelf sedimentary basin characterized by a shift in both the location of the main depocentre and the sources of sediment production

palaeostress analysis of tertiary post collisional structures in the western pontides northern turkey fingerprints of the opening of the western black sea basin and collision of pontides and sakarya continent along the intra pontide suture can be traced in the area between cide kastamonu and kurucasile bartin in northern turkey along the southern coast of the black sea the western black sea basin is an oceanic basin opened as a back arc basin of the northward subducting intra pontide ocean basement units related to this opening are represented by lower cretaceous and older units the first arc magmatism related to this subduction began during turonian times coeval with this magmatism back arc extension affected the region and caused development of horst graben topography this extensional period resulted in the break up of continental crust and the oceanic spreading in the western black sea basin during late santonian times during the late campanian early maastrichtian period the sakarya continent and pontides collided and arc magmatism on the pontides ended after this collision the western pontides thickened imbricated and developed a mainly n vergent foreland fold and thrust belt character since late eocene oligocene times the palaeostress directions calculated from thrust faults of this foreland fold and thrust belt are 4 6 156 6 for 1 6 4 66 1 for 2 and 83 2 261 9 for 3 the nature of the imbrica tion indicates that it was a northward prograding foreland system connected to a floor thrust detach ment fault at the bottom field observations on curved slickenfibres support the theory that the thrust faults of this imbricated structure have transformed to oblique thrusts and strike slip faults over time

early diagenetic dolomitization and dedolomitization of late jurassic and earliest cretaceous platform carbonates a case study from the jura mountains nw switzerland e france early diagenetic dolomitization is a common feature in cyclic shallow water carbonates throughout the geologic record after their generation dolomites may be subject to dedolomitization re calcification of dolomites e g by contact with meteoric water during emersion these patterns of dolomitization and subsequent dedolomitization frequently play a key role in unravelling the development and history of a carbonate platform on the basis of excellent outcrops detailed logging and sampling and integrating sedimentological work high resolution sequence stratigraphic interpretations and isotope analyses o c conceptual models on early diagenetic dolomitization and dedolomitization and their underlying mechanisms were developed for the upper jurassic lower cretaceous jura platform in north western switzerland and eastern france three different types of early diagenetic dolomites and two types of dedolomites were observed each is defined by a distinct petrographic isotopic signature and a distinct spatial distribution pattern different types of dolomites are interpreted to have been formed by different mechanisms such as shallow seepage reflux evaporation on tidal flats and microbially mediated selective dolomitization of burrows depending on the type of dolomite sea water with normal marine to slightly enhanced salinities is proposed as dolomitizing fluid based on the data obtained the main volume of dolomite was precipitated by a reflux mechanism that was switched on and off by high frequency sea level changes it appears however that more than one dolomitization mechanism was active pene contemporaneously or several processes alternated in time during early diagenesis percolating meteoric waters obviously played an important role in the dedolomitization of carbonate rocks that underlie exposure surfaces cyclostratigraphic interpretation of the sedimentary succession allows for estimates on the timing of early diagenetic de dolomitization these results are an important step towards a better understanding of the link between high frequency probably orbitally forced sea level oscillations and early dolomitization under mesozoic greenhouse conditions

western versus eastern black sea tectonic evolution pre rift lithospheric controls on basin formation abstract we demonstrate the key role of pre rift rheology on the kinematics of basin formation in the western and eastern black sea basins constraints on modelling results are provided by a large data set based on more than 50 000 km of multichannel seismics offshore and onshore wells regional gravity and magnetic surveys refraction seismics and field studies the model supports the presence of important differences in the thickness and in the thermal state of the lithosphere which rifted to form the western middle barremian and the eastern middle paleocene black sea subbasins a 200 km and a 80 km thick pre rift lithosphere appear to have driven the deformation in the western and in the eastern black sea respectively differences in the geometry and in the mechanical properties of the pre rift lithosphere have a strong control on the depth of necking and thus on the basin morphology the model sheds light on palaeotectonic and palaeogeographic reconstructions duration of rifting events location of subsiding areas and erosional surfaces the western and the eastern parts of the black sea appear to be two distinct basins characterised by different evolutionary paths determined by different pre rift conditions

depositional cycles composite sea level changes cycle stacking patterns and the hierarchy of stratigraphic forcing examples from alpine triassic platform carbonates carbonate platform deposits record a complex interplay of numerous geodynamic variables of which eustasy subsidence and sediment accumulation are prime factors in determining both the kilometer scale depositional sequence scale and meter scale depositional cycle scale stratigraphic packaging in this study we looked particularly at composite eustasy that is superimposed sea level fluctuations with different frequencies defined as orders and different amplitudes and the role it plays in the linkage between meter scale cyclic stratigraphy and kilometer scale sequence stratigraphy specifically we have investigated the relationship between low frequency third order 1 10 m y period depositional cycles and their component high frequency fourth 0 1 1 m y and fifth 0 01 0 1 m y order cycles through detailed stratigraphic analyses of alpine triassic platforms complemented by computer modeling on the basis of our results we suggest that in general there exists a hierarchy of stratigraphic forcing driven by composite eustasy that results in organized stacking patterns thickness subfacies character early diagenetic attributes of high frequency typically fourth and fifth order shallow water carbonate cycles dictated by low frequency third order relative sea level effects we suggest that systematic vertical changes in stacking patterns of high frequency cycles across a larger depositional sequence are due to systematic and predictable differences in depositional space available during the rising and falling stages of a relative third order sea level change we also suggest that these systematic variations in cycle stacking patterns will exist regardless of the mechanism responsible for generating the high frequency cycles be it an autocyclic or allocyclic mechanism this approach has major implications for the use of high frequency fourth and fifth order cycle characteristics to identify third order cycles in outcrops and cores of shallow water carbonates where stratigraphic control may be less than desirable this would constitute a valuable bridge between cyclic stratigraphy at the meter scale and sequence stratigraphy at the seismic scale we present two examples from triassic buildups of the alps the ladinian latemar buildup and the norian dolomia principale where a systematic succession of high frequency cycle stacking patterns and early diagenetic features exists within an overriding third order cycle sequence reflecting the interplay of short term high frequency fourth fifth order eustasy and long term low frequency third order eustasy in accordance with the hierarchy of stratigraphic forcing central to the interpretation of these examples is the demonstration that true eustatic rhythms are recorded in the high frequency cyclicity as verified by time series analyses and the use of fischer plots these examples can be modeled by computer under conditions of lag depth constrained sedimentation uniform subsidence and composite eustasy we also present two examples one from the alpine triassic the norian lofer cyclothems and one from the pleistocene of south florida that lack both a systematic succession of high frequency cycle stacking patterns and identifiable composite rhythms in the stratigraphic record despite the existence of composite high frequency eustasy in these examples we call upon 1 local tectonic forcing in the form of short term deviations in subsidence via faulting lofer example and 2 large differences in the relative amplitudes of different orders of high frequency sea level oscillations pleistocene example to explain the lack of composite rhythms and we present computer simulations to illustrate the concepts an understanding of composite relative sea level changes and the potential for a hierarchy of stratigraphic forcing provides the link between cyclostratigraphy and sequence stratigraphy and also has important implications regarding the stratigraphy of early diagenesis

stratigraphic evolution of the late jurassic hanifa formation along the tuwaiq escarpment saudi arabia evidence for a carbonate ramp system abstract a sequence stratigraphic framework of the late jurassic oxfordian hanifa formation at its exposure in central arabia is presented for the first time this study offers the first high resolution stratigraphic framework of the hanifa along the tuwaiq escarpment by measuring 15 sections 770 m total thickness over an oblique to dip distance of 260 km and collecting 295 samples for petrographic analysis on the basis of these data the hanifa formation can be subdivided into eight facies 1 tabular cross bedded quartz peloidal skeletal grainstone 2 cross bedded skeletal peloidal grainstone 3 bioturbated foraminiferal wackestone mud dominated packstone 4 oncolitic rudstone 5 stromatoporoid coral biostrome bioherm 6 peloidal composite grain grain dominated packstone grainstone 7 bioturbated spiculitic wackestone mud dominated packstone and 8 thinly bedded argillaceous mudstone wackestone the vertical and lateral distributions of these facies along the exposure define their sequence setting using the principals of sequence stratigraphy by recognizing erosional surfaces facies offset and changes in facies proportions five third order sequences with an average duration of 1 1 myr are interpreted for the hanifa formation the correlation of the sequences across the study area shows that only four sequences are preserved in the north where shallow water deposits are well developed facies trends within these sequences are further illustrated in depositional models representing the highstand systems tracts hst and the transgressive systems tracts tst of the hanifa formation these proposed models represent depositional settings of a carbonate ramp with normal open marine conditions the hst depositional model is characterized by a high energy shoreline and depicts the presence of an offshore structurally controlled skeletal peloidal shoal body described here for the first time at the hanifa exposure in the hozwa area this work provides a predictive framework and outcrop analog for applications in hydrocarbon exploration and development furthermore a basinal setting predicted to the south of the study area is a potential site for unconventional plays

intraplate stresses a new tectonic mechanism for fluctuations of relative sea level stress variations in the lithosphere of a few hundred bars can explain the major part of the seismostratigraphic record at passive margins and intracratonic basins however to induce apparent sea level fluctuations with magnitudes greater than 50 m changes in stress level of more than 1 kbar are required these must be related to major reorganizations at convergent plate boundaries fragmentation of plates or collision processes specific rapid falls in the vail et al curves can be associated quantitatively with particular plate tectonic reorganizations of lithospheric stress fields the seismostratigraphic record may provide a new source of information on paleo stress fields to be correlated with results of independent numerical modeling of intraplate stresses

generation of oceanic island basalt type volcanism in the western trans mexican volcanic belt by slab rollback asthenosphere infiltration and variable flux melting mantle plumes or decompression melting of a heterogeneous mantle have been proposed to explain oceanic island basalt oib type lavas found in the western trans mexican volcanic belt we show that mantle plumes cannot account for several geologic observations whereas decompression melting is unrealistic given the low extension rate in the volcanic arc on the basis of new geologic and geochemical studies we propose an alternative model that reconciles geologic data plate tectonic history and petrology since 8 5 ma the volcanic front has migrated trenchward 80 km and oib began to be emplaced in the rear half of the arc after a period of stalled subduction of the rivera plate between 7 2 and 4 8 ma as a whole oib accounts for 5 of the total volume of volcanism their trace element signatures require an enriched mantle source akin to the deep asthenosphere but also indicate a minor involvement of a subduction component we propose that during the period of very low convergence at the end of the miocene the leading edge of the rivera slab started to sink into the mantle and continued rolling back until it reached the present dip of 45 the sinking of the slab may have induced small amounts of asthenosphere to flow laterally into the opening mantle wedge from the gulf of california rift on the west and through the subducted rivera cocos plate boundary on the east this mechanism would produce veins of relatively enriched mantle which would be able to produce melts with an oib composition once the flux of fluids released from the subducted slab resumed

fault activity and sedimentation in a marine rift basin upper jurassic wessex basin uk shallow marine carbonates and siliciclastics of the corallian formation oxfordian early kimmeridgian accumulated on and around an intrabasinal high in the extensional wessex basin four sequences can be recognized sequences 1 3 accumulated under conditions of thermal subsidence on a ramp type margin the initial sequence was siliciclastic highstand sedimentation in this sequence reflects the supply of sandy mud from a recently emergent intrabasinal high during transgression and regression this muddy sediment was reworked into cleaner sandstone bodies by landward or basinward migrating zones of shoreface erosion carbonates dominate the second and third sequences when rising sea level increased the area of carbonate production and reduced siliciclastic input oolite bodies developed as both transgressive barrier bars and highstand sheets the forth sequence formed during the activation of major normal faults this caused the breakdown of the ramp system and patterns of sediment accumulation were strongly controlled by tectonic subsidence patterns

simulation of the tropical thermal domes in the atlantic a seasonal cycle abstract a general ocean circulation model is used to analyze seasonal variations in the guinea dome and angola dome regions the cold guinea dome develops from june through september due to active divergence of heat transport the cooling is related to upwelling generated by the local wind stress curl associated with the northeast trade winds the guinea dome thus provides an active mechanism of absorbing heat from the atmosphere the coastal guinea region experiences semiannual warming in april july and november december due to intrusion of coastal downwelling kelvin waves from the equatorial region the angola dome in the southern hemisphere is found to be cooled from march through august the surface flux plays a major role in the seasonal variation of the heat budget in contrast to the situation of the guinea dome in the northern hemisphere the angola front located at the northern border of the cold angola dome becomes distinguishable particularly during the boreal fall because of the intrusion of w

the cenomanian turonian boundary at eastbourne sussex uk a proposed european reference section the cenomanian turonian boundary ctb section at eastbourne sussex england is the thickest at outcrop in the anglo paris basin is rhythmic throughout rich in macro micro and nanno fossils and shows less diagenetic alteration than other sections in nw europe geochemical and biostratigraphic data are all related to detailed rhythmic lithostratigraphy allowing correlation with the global boundary stratotype section to within 20 000 years and accurate estimates of rates of changes very detailed stable isotope curves for oxygen and carbon are presented and show that the build up phase of the ctb carbon excursion had two portions separated by a trough patterns of occurrence of coarse fraction benthic foraminifera 250 mm show two peaks of extinction corresponding to the two build up phases of the carbon excursion benthic and planktic foraminifera ostracods and calcareous nannofossils all show declines in diversity and abundance across the ctb foraminifera also decline significantly in size key biomarker events for the ctb include first occurrences of the ammonites fagesia catinus and mammites nodosoides the bivalve mytiloides the planktic foraminifera helvetoglobotruncana praehelveticaand marginotruncana renzi and the calcareous nannofossils quadrum intermedium q gartneri and eprolithus octopetalus and last occurrences of the ammonite sciponoceras the planktic foraminifera rotalipora greenhornensis and r cushmani the calcareous nannofossils corolithion kennedyi axopodorhabdus albianus lithraphidites acutus rhagodiscus asperand microstaurus chiastius cyclostratigraphy allows very precise correlation of isotopic and bioevents with other sections in europe and north america eastbourne is recommended as a nw european standard section 1999 elsevier science b v all rights reserved

integrated stratigraphy of the kimmeridge clay formation upper jurassic based on exposures and boreholes in south dorset uk for the purposes of a high resolution multi disciplinary study of the upper jurassic kimmeridge clay formation two boreholes were drilled at swanworth quarry and one at metherhills south dorset uk together the cores represent the first complete section through the entire formation close to the type section we present graphic logs that record the stratigraphy of the cores and outline the complementary geophysical and analytical data sets gamma ray magnetic sus ceptibility total organic carbon carbonate 13 c org of particular note are the new borehole data from the lowermost part of the formation which does not crop out in the type area detailed logs are available for download from the kimmeridge drilling project web site at http kimmeridge earth ox ac uk of further interest is a mid eudoxus zone positive shift in the 13c org record a feature that is also registered in tethyan carbonate successions suggesting that it is a regional event and may therefore be useful for correlation the lithostratigraphy of the cores has been precisely correlated with the nearby cliff section which has also been examined and re described magnetic susceptibility and spectral gamma ray measurements were made at a regular spacing through the succession and facili tate core to exposure correlation the strata of the exposure and core have been subdivided into four main mudrock lithological types a medium dark dark grey marl b medium dark dark grey greenish black shale c dark grey olive black laminated shale d greyish black brownish black mudstone the sections also contain subordinate amounts of siltstone limestone and dolostone comparison of the type section with the cores reveals slight lithological variation and notable thick ness differences between the coeval strata the proximity of the boreholes and different parts of the type section to the purbeck isle of wight disturbance is proposed as a likely control on the thickness changes

interannual variability of the guinea dome and its possible link with the atlantic meridional mode using a high resolution ocean general circulation model forced by ncep ncar reanalysis data the interannual variability of the guinea dome is studied from a new viewpoint of its possible link with the atlantic meridional mode amm which is related to the meridional migration of the intertropical convergence zone itcz the dome develops off dakar seasonally from late spring to late fall owing to the wind induced ekman upwelling its seasonal evolution is associated with the northward migration of the itcz when the itcz is located anomalously northward southward from late spring to early summer as a result of the wind evaporation sea surface temperature sst positive feedback with positive negative sst anomaly over the northern hemisphere the dome becomes unusually strong weak in fall as a result of stronger weaker ekman upwelling this may contribute to the decay of the amm thus the coupled nature between the amm and the guinea dome could be important in understanding modeling and predicting the tropical atlantic variability

cretaceous oceanic red beds corbs different time scales and models of origin abstract the cretaceous oceanic red bed corb is a newly opened window on global oceanic and climate changes during the cretaceous greenhouse world as a result of the international geoscience programmes 463 494 and 555 2002 2010 corbs have been documented in many places by numerous publications the principle goal of this paper is to summarize scientific advances on corbs including chronostratigraphy sedimentology mineralogy elemental and isotopic geochemistry and their relationship to oceanic anoxic events oaes palaeoclimate and palaeoceanography we propose a new geochemical classification of the corbs using cao al 2 o 3 and sio 2 values which lithologically refer to marly clayey and cherty corbs respectively detailed mineralogical studies indicate that hematite goethite and mn 2 bearing calcite are the minerals imparting the red color of corbs hematite clusters of several to tens of nanometers in the calcite structure are the main cause of the red coloring of limestones and the mn 2 bearing calcite gives additional red color goethite was thought to form originally with hematite and was subsequently transformed to hematite during late diagenesis chronostratigraphic data allow the distinction of two groups of corbs by their durations short term corbs are generally less than 1 myr in duration and seem to be on the scale of milankovitch cycles during the deposition of cretaceous reddish intervals from odp cores 1049 and 1050 low primary productivity and relatively high surface temperature resulted in low organic carbon flux into the sediments which reduced oxygen demand and produced oxidizing early diagenetic conditions in such an oxic environment iron oxides formed imparting the reddish color the long term corbs depositional events lasted longer than 4 myr and may be a possible consequence of the oaes enhanced amounts of organic carbon and pyrite burial during and after the oaes would have resulted in a large and abrupt fall in atmospheric co 2 concentration which probably induced significant global climatic cooling during and after the oaes global cooling would have enhanced formation of cold deep water increasing its oxidizing capacity due to the greater content of dissolved oxygen and would promote formation of oceanic red beds sedimentological mineralogical and geochemical data indicate that corbs were deposited under highly oxic oligotrophic conditions probably at a low sedimentation rate the cretaceous red and white limestones from italy have similar compositions of terrestrial input sensitive elements al ti k mg rb zr higher contents of fe 2 o 3 and depleted redox sensitive elements v cr ni and u and micronutrient elements cu zn indicating similar provenance sources but red limestones were deposited under more oxic conditions at the sediment water interface than white limestones the cretaceous red shales such as those from the north atlantic and tibet have similar mineralogy and geochemistry as the late cenozoic red clays in the pacific ocean and the environment where both are formed was well oxidizing at a very low sedimentation rate we compiled seventeen published stratigraphic examples of phanerozoic oceanic red beds including the late cenozoic red clays in the pacific different hypotheses explain the origin of red pigmentation of limestones and shales including 1 detrital origin of iron derived from continental weathering 2 iron bacterial mediation at the time of sedimentation and 3 iron oxidation in oligotrophic highly oxic environment additional research on phanerozoic oceanic red beds is needed in order to better document their origin and palaeoceanographic and palaeoclimatic significance

test of the concepts of sequence stratigraphy in the kimmeridgian late jurassic of england and northern france abstract three distinct models are available for the prediction of sediment accumulation patterns the sequence stratigraphic models of both galloway 1989 and exxon are derived from passive margins whereas the model of einsele 1985 is based on marginal sedimentation in epicontinental seas the models are tested on the marine mudrocks and minor sandstones of the kimmeridgian epicontinental seas of england and northern france a total of ten hiatus bounded sedimentary packages sequences can be delimited and aspects of both the exxon and galloway models are applicable however only a few of the sequence boundaries correspond to the eustatic sea level chart of haq et al 1989 the sequence boundaries appear to be caused by falls in a base level controlled by a storm wave base and the transgressive regressive cycles appear symmetrical as predicted by the einsele model in both the exxon and galloway models condensed sections are predicted to form in distal basin settings beyond the reach of terrigenous sediments but they are not developed in the relatively small kimmeridgian half grabens which were infilled with non progradational packages of sediment thus the basin centres such as the kimmeridge bay type locality contain the thickest and most complete sequences

on the dynamics of the sri lanka dome in the bay of bengal east of sri lanka in the northern indian ocean a cold dome known as the sri lanka dome sld develops during southwest monsoon season june september the sld first forms around may matures in july and decays around september in association with the strong cyclonic wind stress curl in this study the structure and dynamics of sld in response to the climatic events such as the indian ocean dipole iod are examined our results reveal that these climatic events modulated the subsurface temperature variability in the thermocline at 100 m depth whose signature was also evident in the satellite derived sea surface height ssh anomaly in the sld region we find that the mechanisms for the formation of sld are consistent with previous research and there is year to year variability in the sld dynamics this study also reveals that the atmospheric parameters including vertical wind shear and mid tropospheric relative humidity are high over the sld region and adjacent southern bay of bengal and show an upward increasing trend over the decades this has impacted the atmospheric parameters over the northern bay of bengal over the decades and as a consequence the total number of monsoon depressions june september decreased over the decades from 1980 to 2015 as reported by the india meteorological department new delhi thus the new insight emerged from this study is the variability in the cyclogenesis and the occurrence of total number of monsoon depressions over northern bay of bengal over the decades are much related to the sld dynamics

abrupt transition from magma starved to magma rich rifting in the eastern black sea the amount of magmatism that accompanies the extension and rupture of the continental lithosphere varies dramatically at rifts and margins around the world based on widely spaced geophysical transects some margins are known to preserve a transition from magmatically robust to magmatically starved rifting along strike but the nature of the transition is unknown wide angle seismic data from the black sea provide the first direct observations of such a transition and show that it is abrupt occurring over only 20 30 km and coincides with a transform fault this abrupt transition cannot be explained solely by gradual along margin variations in mantle properties since these would be expected to result in a smooth transition from magma poor to magma rich rifting over hundreds of kilometers we suggest that the abruptness of the transition results from the development of three dimensional 3 d melt migration due to along strike variations in extension and thus the thickness of the lithosphere at the time of rifting localized magmatic addition attributed to melt focusing has been observed in modern mid ocean ridges and active rift environments but here we show that such processes can also produce abrupt along strike changes from magma poor to magma rich rifting

a u pb and 40ar 39ar time scale for the jurassic published time scales provide discrepant age estimates for jurassic stage boundaries and carry large uncer tainties the u pb or 40 ar 39 ar dating of volcaniclastic rocks with precisely known stratigraphic age is the preferred method to improve the calibration a radiometric age database consisting of fifty u pb and 40 ar 39 ar ages was com piled to construct a revised jurassic time scale accepted ages have a precision of 5 ma 2 or better and are con fined to no more than two adjacent stages the majority of these calibration points result from integrated bio and geochronologic dating in the western north american cordillera and have not been previously used in time scales di rect dates are available only for the triassic jurassic boundary and the initial boundary of the crassicosta chron and the callovian stage the chronogram method was used to estimate all early and early middle jurassic zone boundaries attempted here for the first time late middle jurassic substage boundaries and late jurassic stage boundaries signif icant improvement is achieved for the pliensbachian and toarcian where six consecutive zone boundaries are deter mined the derived zonal durations are disparate varying between 0 4 and 1 6 ma the latest jurassic isotopic database remains too sparse therefore chronogram estimates are improved using interpolation based on magnetochronology the initial boundaries of jurassic stages are proposed as follows berriasian jurassic cretaceous 1418 18

the kapanbogazi formation a key unit for understanding late cretaceous evolution of the pontides n turkey abstract the pontides forming the south western continental margin of the black sea consist of two tectonic units the istanbul zone in the west and the sakarya zone in the central and eastern parts the sinop basin in the sakarya zone is filled from base to top by hauterivian to albian turbidites cenomanian turonian red pelagic sediments turonian campanian magmatic arc and related deposits and by the uppermost campanian to middle eocene post magmatic units developed on the southern passive margin of the black sea based on nannofossil dinoflagellate foraminifera and radiolaria data we describe the kapanbogazi formation a cenomanian turonian unit in the sinop basin represented by red calcareous siliceous pelagic shales limestones and cherts passing gradually from the albian black shales these sediments possibly represent deepest depositional conditions of the basin during the cenomanian turonian interval and also reflect the transition from an anoxic to an oxic palaeoenvironmental setting the istanbul zone to the west was emerged during the deposition of the kapanbogazi formation in the sakarya zone in the pontides red pelagic sediments were deposited at different times during the cenomanian maastrichtian interval because the kapanbogazi formation was deposited only in the sakarya zone and because it is present in limited outcrops due to structural reorganization and thick overlying volcanoclastic pile most previous authors assumed cenomanian turonian hiatus herein we describe detailed palaeontological data from this unit and discuss their importance to the interpretation of depositional history and tectonics of the black sea region as well as climatic and eustatic implications

3 geochronology and geodynamics of late cretaceous magmatism and cu au mineralization in the panagyurishte region of the apuseni banat timok srednogorie belt bulgaria abstract the apuseni banat timok srednogorie abts belt europe s most extensive belt of calc alkaline magmatism and cu au mineralization is related to the subduction of the tethys ocean beneath the european continental margin during the late cretaceous phase of the alpine himalayan orogeny economic deposits are restricted to certain segments along the belt and all major porphyry style and high sulphidation ore deposits in bulgaria are aligned on the panagyurishte corridor a narrow zone obliquely crossing the abts belt this paper reviews the geology geochemistry and geochronology of igneous and hydrothermal events along this corridor in a profile extending from the european continental basement in the north to the accretionary complex of the rhodopes in the south extensive u pb dating of zircons from subvolcanic intrusions and major plutons supplemented by published age data for magmatic rocks and hydrothermal ore deposits obtained by other methods reveals a general younging of magmatism from ca 92 ma in the north elatsite to ca 78 ma in the south capitan dimitrievo cu au deposits are restricted to the northern and central parts of the profile ranging in age from 92 to 86 ma while the southernmost part exposes more deeply eroded mid crustal plutons devoid of economic mineralization the age progression correlates with a north to south geochemical trend of decreasing crustal input into mantle derived magmas magmatism and ore formation in individual magmatic hydrothermal complexes along the profile is much shorter lived for example subvolcanic intrusions and porphyry cu au mineralization at the elatsite deposit and andesitic volcanism and high sulphidation au as cu mineralization at chelopech all occurred within a time span of about 1 million years the age progression of calc alkaline magmatism within the panagyurishte region bulgaria from north to south is explained as a consequence of slab retreat during oblique subduction this led to transtensional block faulting and subsidence and thus to the preservation of near surface magmatic hydrothermal products including economic cu au deposits accretion of continental fragments in the rhodopes south of the abts belt led to greater uplift of the youngest late cretaceous intrusions this removed any ore deposits that might have been formed in this area

a sequence stratigraphy of the kimmeridgian and bolonian stages late jurassic wessex weald basin southern england a sequence stratigraphic framework for the late jurassic kimmeridgian and bolonian stages of the wessex weald basin southern england is proposed based on the integration of sedimentological geophysical and geochemical data the nerc funded rapid global geological events rgge boreholes of swanworth quarry 1 and 2 and metherhills 1 are used as reference sections eleven complete depositional sequences and their component systems tracts are recognized within the kimmeridge clay formation bounded by 12 sequence boundaries km1 12 seventy four boreholes have been used in this study during the kimmeridgian a major transgression associated with tectonic movements led to a marked change in basin geometry major deepening of the sea during the late kimmeridgian eudoxus zone led to a change from unconformities of basinwide extent to those confined to the basin margins the progressive deepening of the basin towards a highstand in the mid bolonian wheatleyensis to pectinatus zones was associated with a broad scale change in sedimentary faunal and geochemical characters the layer cake basin architecture and thickening of the kimmeridge clay formation towards the basin centre suggests a dominantly aggradational system the partially enclosed nature of the kimmeridgian and bolonian seas generated basin dynamics more analogous to those of modern day meromictic lakes consequently sequence stratigraphic approaches derived from continental shelf margins are inappropriate in epicontinental basins of this type

the black sea back arc basin insights to its origin from geodynamic models of modern analogues the black sea is generally thought to be a back arc basin with active extension rifting beginning in late early cretaceous times although some fundamental issues such as the presence or absence of a related magmatic arc and the orientation of the related driving subduction zone remain vaguely defined at best however as shown here the regional structure of the black sea is consistent with that predicted by geodynamic models of modern back arc basin formation in which extension is driven by slab roll back this includes an asymmetric distribution of horst and graben structures in the back arc basin the distribution and spacing of which is related to the strength of the underlying lithosphere which forms the hanging wall of the subduction zone by analogy the intrabasinal structure of the black sea as a whole is explicable as the consequence of a single phase of asymmetric back arc basin formation not two separate phases independently responsible for its western and eastern segments and its underlying lithosphere is rheologically strong as predicted by recent models of precambrian europe and present day tomography

obduction subduction and collision as reflected in the upper cretaceous lower eocene sedimentary record of western turkey late cretaceous early eocene tethyan evolution of western turkey is characterized by ophiolite obduction high pressure low temperature metamorphism subduction arc magmatism and continent continent collision the imprints of these events in the upper cretaceous lower eocene sedimentary record of western anatolia are studied in thirty eight well described stratigraphic sections during the late cretaceous period western turkey consisted of two continents the pontides in the north and the anatolide taurides in the south these continental masses were separated by the izmir ankara neo tethyan ocean during the convergence the pontides formed the upper plate the anatolide taurides the lower plate the arc magmatism in the pontides along the black sea coast is biostratigraphically tightly constrained in time between the late turonian and latest campanian ophiolite obduction over the passive margin of the anatolide tauride block started in the santonian soon after the inception of subduction in the turonian as a result large areas of the anatolide tauride block subsided and became a region of pelagic carbonate sedimentation during the campanian the leading margin of the anatolide tauride block was buried deeply and was deformed and metamorphosed to blueschist facies during campanian times the campanian arc volcanic rocks in the pontides are conformably overlain by shaley limestone of maastrichtian palaeocene age however maastrichtian sedimentary sequences north of the tethyan suture are of fore arc type suggesting that although arc magmatism ceased by the end of the campanian age continent continent collision was delayed until palaeocene time when there was a change from marine to continental sedimentation in the fore arc basins the interval between the end of the arc magmatism and continent continent collision may have been related to a northward jump of the subduction zone at the end of campanian time or to continued obduction during the maastrichtian

depositional sequences in shallow carbonate dominated sedimentary systems concepts for a high resolution analysis abstract oxfordian and berriasian sections representing shallow water carbonate dominated sedimentary systems have been studied in the swiss and french jura in spain and in normandy they all display a hierarchical stacking of depositional sequences facies evolution and stacking pattern allow to define elementary small scale medium scale and large scale sequences some depositional sequences display well marked sequence boundaries others are limited by transgressive or maximum flooding surfaces the hierarchical organisation of such sequence stratigraphic elements implies that sea level fluctuations were an important factor in their formation and that these fluctuations had different frequencies the superposition of high frequency sea level changes on a long term sea level trend leads to repetition of diagnostic surfaces defining sequence boundary and maximum flooding zones wherein the corresponding high frequency surfaces are well developed chronostratigraphic tie points permit us to estimate the duration of large scale sequences this time control and the observed hierarchical stacking suggest that the high frequency sea level changes were controlled by climatic cycles in the milankovitch frequency band the variability of stacking pattern and facies evolution between sections illustrates the complexity of the studied environments furthermore because of the minimal accommodation space available in these shallow water settings much of the geologic time is not recorded nevertheless detailed analysis of the depositional sequences allows the interpretation of the evolution of the sedimentary system with a high time resolution thus there is a potential to monitor sedimentological ecological and diagenetic processes on a time scale of 20 to 100 ka

contemporaneous ascent of within plate type and island arc type magmas in the beppu shimabara graben system kyushu island japan abstract within plate wp type and island arc ia type magmas have erupted in north kyushu and south kyushu respectively during quaternary time the former is related to the eastern end of the east asian extensional province and the latter to the subduction zone of the philippine sea plate the beppu shimabara graben system in the central part of kyushu island is located in the area of overlap between them quaternary volcanic rock samples from the graben system can be chemically classified as wp and ia types by their multi element patterns and positions on a zr nb y discrimination diagram rocks of both type and of similar ages occur throughout the graben system furthermore the rocks of wp type give systematically higher 87sr 86sr ratios 0 7048 0 7049 than those of the associated ia type around 0 7040 the relations between 87sr 86sr and nb y ratios of the former are clearly distinguished from those of the latter these results demonstrate that this graben system is characterized by the contemporaneous ascents of wp and ia type magmas to the same quaternary volcanic areas such rivalrous ascents of wp and ia type magmas seem to be a common feature of magmatism associated with graben in extensional provinces related to subduction zones of island arcs and their boundary areas

seasonal and interannual variations of oceanic conditions in the angola dome using outputs from a high resolution ogcm seasonal and interannual variations of the angola dome ad are revisited although the ad was previously considered to be one large cold tongue extending from the west african coast it is shown that two cold domes exist these two domes have remarkably different mechanisms for their seasonal variation the weak dome whose center is located at 6 s 1 e develops from may to september owing to the divergence of heat transport associated with upwelling the strong dome on the other hand extends from the west coast of africa between 20 and 15 s and develops from april to august by the surface heat flux the interannual variation of the weak dome is strongly influenced by the atlantic nino an unusual relaxation of easterly wind stress in the central equatorial atlantic ocean associated with the atlantic nino triggers second baroclinic downwelling equatorial kelvin waves which propagate eastward along the equator and poleward along the coast after reaching the african coast as coastal kelvin waves then downwelling rossby waves radiate away from the coast and cause significant warming in the weak dome region the interannual variation of the south equatorial undercurrent may be associated with that of the ad its transport decreases by 0 6 sv and its core shifts equatorward by 0 2 when the ad is anomalously weak

black pebble occurrence and genesis in holocene carbonate sediments florida keys bahamas and tunisia abstract black carbonate lithoclasts along with blackened peloids ooids skeletal fragments and entire limestone beds are found in the shallow subtidal intertidal and supratidal zones of modern and ancient carbonate environments they are often associated with pedogenic features such as root traces or caliche the blackening is due to impregnation of the sediment by dissolved colloidal or finely particulate organic substances in an anoxic and alkaline environment or microenvironment the organic matter is derived from decayed algae and or decayed or burnt higher terrestrial plants iron sulfides contribute to the blackening especially in samples containing algal matter a complex interplay of adsorption of organic matter on carbonate crystal surfaces neomorphism and microcrystalline cementation in the vadose or freshwater phreatic zones is thought to fix the organic matter and make the black coloration relatively resistant to oxidation black pebbles form through reworking of the preferentially cemented and blackened sediment by coastal erosion they are mostly relics because the less consolidated host sediment is washed away black pebbles may thus be valuable indicators of ancient coastal and terrestrial environments

the black sea basins structure and history new model based on new deep penetration regional seismic data part 1 basins structure and fill abstract this work is based upon results of interpretation of about 8872 km long regional seismic lines acquired in 2011 within the international project geology without limits in the black sea the seismic lines cover nearly the entire black sea basins including russia turkey ukraine romania and bulgaria sectors a new map of acoustic basement relief and a new tectonic structure scheme are constructed for the black sea basins the basement of the black sea includes areas with oceanic crust and areas with highly rifted continental crust a chain of buried seamounts which were interpreted as submarine volcanoes of late cretaceous santonian to campanian age has been identified to the north of the turkish coast on the shatsky ridge probable volcanoes of albian age have also been recognized synorogenic turbidite sequences of paleocene eocene and oligocene ages have been mapped in the cenozoic numerous compressional and transpressional structures were formed in different parts of the black sea basin during the pleistocene quaternary turbidites mass transport deposits and leveed channels were formed in the distal part of the danube delta

deep water facies succession around the cenomanian turonian boundary in the outer carpathian basin sedimentary biotic and chemical records in the silesian nappe poland abstract facies succession organic carbon stable isotopes and chemical data together with benthic foraminiferal records from the barnasiowka trzeme nia composite section silesian nappe poland reflect changing oceanographic conditions across the cenomanian turonian transition in one of the largest basins of the outer carpathians whose floor was situated beneath the calcium compensation depth the sediments consist of non calcareous radiolarian shales turbidite intercalations rich in foraminifers and sponge spicules as well as siliciclastics and black shales with marine type of organic matter toc up to 6 5 wt corresponding to global oceanic anoxic event 2 the base of oae 2 has been identified on the basis of organic carbon isotope data as a positive excursion from 26 0 to the peak of 23 2 in the latest cenomanian the top of the oae 2 lies within a succession of oxidized siliceous manganiferous sediments including a fe mn layer with macronodules the organic rich sedimentation continued for about 400 kyr at a rate of ca 5 5 mm kyr and finished before the start of the turonian deep water agglutinated foraminiferal diversification and extinction of several taxa occurred during the early part of the oae 2 due to expanding bottom water anoxia chemical indices and benthic foraminiferal assemblages reveal periodic intervals of intensification and expansion of oxygen minimum zone at the basin floor before and after the oae 2 two early diagenetic ferromanganese layers with macronodules and siliceous manganiferous red and green shales directly overlying the organic rich facies reflect changes in oxygenation of the bottom water related to changes in their dynamics which took place near the c t boundary and in the earliest turonian this condensed fe mn succession records the maximum flooding of the late cenomanian early turonian transgression

third order depositional sequences reflecting milankovitch cyclicity the origin of third order depositional sequences remains debatable and in many cases it is not clear whether they were controlled by tectonic activity and or by eustatic sea level changes in oxfordian and berriasian valanginian carbonate dominated sections of switzerland france germany and spain high resolution sequence stratigraphic and cyclostratigraphic analyses show that the sedimentary record reflects milankovitch cyclicity orbitally induced insolation changes translated into sea level fluctuations which in turn controlled accommodation changes beds and bedsets formed in rhythm with the precession and 100 kyr eccentricity cycles whereas the 400 kyr eccentricity cycle contributed to the creation of major depositional sequences biostratigraphical data allow the correlation of many of the 400 kyr sequence boundaries with third order sequence boundaries recognized in european basins this implies that climatically controlled sea level changes contributed to the formation of third order sequences furthermore this cyclostratigraphical approach improves the relative dating of stratigraphic intervals

deciphering the history of climate and sea level in the kimmeridgian deposits of bure eastern paris basin abstract an integrated stratigraphic study was conducted on a kimmeridgian succession of 3rd order cycles including marls and limestones in a shelf context at bure paris basin the study was possible due to the exceptional opportunity provided by well boring activities related to the construction of an underground laboratory of the french national agency for radioactive waste management andra studies of macrofossils microfossils sedimentology clay mineralogy isotopic composition c o of shells and organic molecular geochemistry lead to a detailed description of the stratigraphic column which allows us to address the history of sea level and climate changes six transgressive regressive cycles are recognised in the studied kimmeridgian succession in these 3rd order cycles the deepest environments are systematically represented by marls and organic rich sediments whilst the shallowest are represented by limestones these cycles do not correspond to changes in temperatures or carbonate production rates at a regional or global scale on the contrary long term palaeontological sedimentological and geochemical changes during the early kimmeridgian are interpreted as climatically induced these climatic changes are considered as responsible for bringing significant granular carbonate production to an end in contrast to carbonate mud that was deposited in alternation with marls throughout the late kimmeridgian

genesis of collision volcanism in eastern anatolia turkey late cenozoic volcanism in eastern anatolia extends in a broad sw ne trending belt across the arabia eurasia collision zone from the arabian foreland basin in the southwest and to the kars plateau and lesser caucasus in the northeast foreland volcanism is dominated by basaltic shield and fissure eruptions of transitional tholeiitic alkaline composition volcanism on the thickened crust north of the bitlis thrust zone varies from the mildly alkaline volcano nemrut and older mus volcanics in the south through the transitional calc alkaline alkaline volcanoes bingol and suphan and the alkaline volcano tendurek to the calc alkaline volcano ararat and older kars plateau volcanics in the north isotope sr nd and trace element systematics indicate that the lavas from the foreland were derived from the mantle lithosphere of the arabian continent which had been enriched by small volumes of asthenospheric melts over a period of time and that lavas from the alkaline volcanic area around mus and the volcanoes nemrut and tendurek north of the bitlis thrust zone were derived from a lithospheric source of similar composition either from the same underthrust arabian continent or from the bitlis massif microcontinent by contrast the transitional lavas from bingol and suphan and the calc alkaline lavas from ararat and kars were derived from lithosphere carrying a distinct subduction signature inherited from pre collision subduction events positive correlations between 87sr 86sr and sio2 and rb nb and sio2 in the alkaline and transitional lavas suggest that combined assimilation and fractional crystallization was an important process within at least part of the thickened crust of the collision zone trace element covariation diagrams such as y rb indicate the importance of hornblende crystallization at depth and orthopyroxene at shallow levels within the calc alkaline provinces in contrast to the consistently anhydrous crystallization sequences of the alkaline lavas trace element diagrams based on the covariation of compatible and incompatible elements point to moderate low degrees of partial melting with residual clinopyroxene throughout and residual garnet in the foreland province consideration of mineral stabilities mantle solidi and geothermal gradients before and after collision suggest that lithospheric thickening should both increase the thickness of metasomatized lithosphere and depress the metasomatized zone to greater depths probably beneath the amphibole and dolomite breakdown curves perturbation of the thickened lithosphere by delamination of the thermal boundary layer perhaps coupled with local stretching associated with pull apart basins on strike slip fault systems is then sufficient to generate melt the composition of that melt being largely dependent on the enrichment history of the lithosphere in question in eastern anatolia volcanism appears to have started between about 8 and 6 ma ago some 5 ma after the start of rapid uplift of the east anatolian plateau

astrochronology of the late jurassic kimmeridge clay dorset england and implications for earth system processes the late jurassic kimmeridge clay formation kcf is an economically important organic rich source rock of kimmeridgian early tithonian age the main rock types of the kcf in dorset uk include grey to black laminated shale marl coccolithic limestone and dolostone which occur with an obvious cyclicity at astronomical timescales in this study we examine two high resolution borehole records swanworth quarry i and metherhills 1 obtained as part of a rapid global geological events rgge sediment drilling project datasets examined were total organic carbon toc and borehole wall microconductivity by formation microscanner fms our intent is to assess the rhythmicity of the kcf with respect to the astronomical timescale and to discuss the results with respect to other key late jurassic geological processes power spectra of the untuned data reveal a hierarchy of cycles throughout the kcf with similar to 167 m similar to 40 m 9 1 m 3 8 m and 1 6 m wavelengths tuning the similar to 40 m cycles to the 405 kyr eccentricity cycle shows the presence of all the astronomical parameters eccentricity obliquity and precession index in particular similar to 100 kyr and 405 kyr eccentricity cycles are strongly expressed in both records the 405 kyr eccentricity cycle corresponds to relative sea level changes inferred from sequence stratigraphy intervals with elevated toc are associated with strong obliquity forcing the 405 kyr tuned duration of the lower kcf kimmeridgian stage is 3 47 myr and the upper kcf early part of the tithonian stage elegans to fittoni ammonite zones is 3 32 myr two other chronologies test the consistency of this age model by tuning similar to 8 10 m cycles to 100 kyr short eccentricity and similar to 3 5 m cycles to 36 kyr jurassic obliquity the obliquity tuned chronology resolves an accumulation history for the kcf with a variation that strongly resembles that of earth s orbital eccentricity predicted for 147 2 ma to 153 8 ma there is evidence for significant non deposition up to i million years in the lowermost kcf baylei mutabilis zones which would indicate a kimmeridgian oxfordian boundary age of 154 8 ma this absolute calibration allows assignment of precise numerical ages to zonal boundaries sequence surfaces and polarity chrons of the lower m sequence c 2009 elsevier b v all rights reserved

accommodation of transpressional strain in the arabia eurasia collision zone new constraints from u th he thermochronology in the alborz mountains north iran the alborz range of n iran provides key information on the spatiotemporal evolution and characteristics of the arabia eurasia continental collision zone the southwestern alborz range constitutes a transpressional duplex which accommodates oblique shortening between central iran and the south caspian basin the duplex comprises nw striking frontal ramps that are kinematically linked to inherited e w striking right stepping lateral to obliquely oriented ramps new zircon and apatite u th he data provide a high resolution framework to unravel the evolution of collisional tectonics in this region our data record two pulses of fast cooling associated with sw directed thrusting across the frontal ramps at 18 14 and 9 5 7 5 ma resulting in the tectonic repetition of a fossil zircon partial retention zone and a cooling pattern with a half u shaped geometry uniform cooling ages of 7 6 ma along the southernmost e w striking oblique ramp and across its associated nw striking frontal ramps suggests that the ramp was reactivated as a master throughgoing n dipping thrust we interpret this major change in fault kinematics and deformation style to be related to a change in the shortening direction from ne to n nne the reduction in the obliquity of thrusting may indicate the termination of strike slip faulting and possibly thrusting across the iranian plateau which could have been triggered by an increase in elevation furthermore we suggest that 7 6 m y old s directed thrusting predated inception of the westward motion of the south caspian basin

tethyan to boreal correlation in the kimmeridgian using high resolution sequence stratigraphy vocontian basin swiss jura boulonnais dorset ammonite biostratigraphy plays a central role in the definition of jurassic stratigraphy nevertheless the strong provincialism of european ammonite species during the kimmeridgian is a long standing problem in correlation attempts between the boreal and tethyan faunal realms moreover the sequence stratigraphic interpretations for northern and southern europe given in the jurassic chronostratigraphic chart of hardenbol et al in sepm publ 60 chart 1998 are different the present study aims to resolve this correlation problem in order to better understand the connections between the boreal and the tethyan realms during the kimmeridgian a sedimentological and high resolution sequence stratigraphic interpretation is presented for two unpublished sections cras d hermont and roche de mars in the northern swiss jura where recently discovered ammonites display both boreal and tethyan influences then these sections are correlated with the same time interval in the central swiss jura and vocontian basin which belong to the tethyan realm lastly a long distance transect is constructed between the vocontian basin swiss jura northern france and southern england the last two areas being part of the sub boreal realm the main results of this work are that 1 third order depositional sequences and also higher frequency sequences can be correlated from the tethyan to the boreal realm 2 the sequence stratigraphic interpretation given by hardenbol et al in sepm publ 60 chart 1998 for northern europe seems to be accurate and agrees with the sequence stratigraphic framework established in the swiss jura 3 the late kimmeridgian of the swiss jura displays boreal influences 4 integrated high resolution sequence stratigraphic and cyclostratigraphic studies are a valuable approach for bridging the correlation gap between northern and southern europe

stratigraphic comparisons along the pontides turkey based on new nannoplankton age determinations in the eastern pontides geodynamic implications we compared the stratigraphic formations along the southern margin of the black sea using 196 nannoplankton ages determined in the western and central pontides and 112 new samples from the eastern pontides we inferred that the istanbul and sakarya zones were amalgamated prior to the early cretaceous extensional subsidence migrated eastwards along the pontides from the barremian to the palaeocene an eastwards younging of the cretaceous magmatism suggested that the eastern black sea basin is younger locally angular unconformities and a stratigraphic gap testify to the late albian uplift of the central pontides as the consequence of the collision of an oceanic edifice cretaceous oceanic red beds are marker beds of santonian age along the much of the pontides and are of mainly campanian age within the eastern pontides the middle campanian paleocene was a non volcanic period characterized by extensional subsidence mainly along the eastern black sea basin the end of cretaceous volcanism can be correlated with a southwards subduction jump syn compressional basins show that contraction started during the ypresian along the entire pontide belt eocene volcanism started earlier in the north lutetian than in the south bartonian of the eastern pontides this propagation of syn collisional volcanism could have resulted from slab steepening under the eastern pontides

seasonality and interannual variability of the sri lanka dome abstract located in the southwest bay of bengal the sri lanka dome sld is an upwelling tropical thermal dome that forms in a region of positive wind stress curl within the southwest monsoon current smc system here we quantify variability in the sld s sea surface slope area amplitude and position using a 22 year record of absolute dynamic topography we observe a seasonal cycle in the evolution of the sld and its relationship to wind stress curl the sld typically forms in early june in a region of positive wind stress curl associated with the wind jet off sri lanka for the first two months after formation the magnitude of the sld s sea surface slope strongly correlates with the strength of the wind stress curl later in the southwest monsoon the sld s position shifts northward moving out of the region of strong wind stress curl before dissipating in typically september the amplitude and area of the sld vary together and both are linked to the strength of the smc on weekly timescales decadal variability in both the sld and wind stress curl is reflected in the dipole mode index which reflects an integrated measure of regional forcing these results suggest alignment between the smc and the region of wind stress curl may play a pivotal role in controlling the strength of the sld on seasonal and interannual timescales

sequence stratigraphy and bedding rhythms of an outer ramp limestone succession late kimmeridgian northeast spain facies stratal and spectral analyses of an outer ramp lime mudstone succession aguilon north iberian ranges spain are presented in this work the studied succession is late kimmeridgian eudoxus and beckeri zones in age and comprises the transgressive and highstand deposits of a third order depositional sequence a number of higher order sequences bundles and sets of bundles have been identified based on the comparative analysis of the bedding planes the bundles and sets of bundles show a well defined stratal pattern spectral analysis has provided further independent confirmation of the cyclical nature of the bundles and sets of bundles defined from field analysis the bundles have variable thickness from 1 to 2 m and are formed by up to 10 micritic beds they have been related to sea level changes controlled by the orbital precession cycle affecting the shallow productivity area a significant amount of the lime mudstones accumulated in outer ramp settings were derived from resedimentation of the shallow carbonate production areas many of the bundles show a lower interval with a thinning and fining up trend indicating a progressive decrease of the carbonate production and carbonate export during periods of high frequency sea level rise the late transgressive and highstand deposits show sets of bundles groups of five bundles from 5 to 8 m probably related to sea level changes controlled by the short eccentricity cycle the overall thickness and the stacking pattern observed in the sets of bundles are controlled by the long term sea level variation the sets of bundles located in the late transgressive deposits show thinner micritic beds in their lower or middle part the sets of bundles found in the highstand deposits are thinner and show a thickening up and thinning up trend on the studied carbonate ramp during periods of long term sea level rise the overall carbonate production and carbonate export is high although the superposition of the high frequency sea level rises may result in episodic flooding and drowning of the shallow ramp areas during periods of long term early highstand of sea level the overall carbonate production and carbonate export is more reduced but it has maximum peaks during the transgressive and early highstand intervals of the high frequency sea level cycles sedimentation during the long term sea level fall late highstand was scarce and discontinuous in the outer ramp area and resulted in the overall thickness reduction of the sets of bundles d 2003 elsevier science b v all rights reserved

late cretaceous stratigraphy in the mudurnu goynuk basin turkey and inferences on sea level change in the late campanian to early maastrichtian upper cretaceous strata at goynuk northwestern anatolia turkey provide a geological record of the campanian maastrichtian from the sakarya terrane along the active neotethys margin shales and shaly marls with siliciclastic and volcaniclastic intercalations indicate a pelagic palaeoenvironment rich in planktonic and benthonic foraminifera and calcareous nannofossil assemblages a composite record from the campanian to the maastrichtian records nannofossil standard zones uc15c cc21 to uc20a cc26 as well as the globotrunanella havanensis planktonic foraminifera zone to the racemiguembelina fructicosa planktonic foraminifera zone the complete mid campanian to early maastrichtian composite section can be correlated to other western tethyan sections the campanian maastrichtian boundary is positioned between the first occurrence of the planktonic foraminifera gansserina gansseri and the last occurrence of the nannofossil uniplanarius trifidus clastic input and higher sedimentation rates constrain regional sea level lowstands around the late campanian calcarata zone and the campanian maastrichtian boundary corresponding to the campanian maastrichtian boundary event

cyclostratigraphy and sequence boundaries of inner platform mixed carbonate siliciclastic successions barremian aptian zonguldak nw turkey abstract barremian aptian shallow marine mixed carbonate siliciclastic successions of the zonguldak area nw turkey have been studied in detail along three measured stratigraphic sections field and laboratory analysis of microfacies and sedimentary structures have demonstrated that sections are composed of meter scale shallowing upward cycles cyclicity of shallow water mixed carbonate siliciclastic successions are generally observed in the form of alternating sandstone siltstone or sandy limestone and limestone a prominent level of charophyte packstone within the successions of zonguldak and kozlu is interpreted as a sequence boundary in the cengellidere section cyclicity is generally represented by an alternation of sandstone conglomerate and bioclastic limestone the first level of conglomerate within the section is interpreted as a sequence boundary smaller scale cyclic arrangements are also recorded within meter scale cycles 4th 5th and 6th order cycles are superimposed and create a hierarchical stacking however 6th order cycles present a relatively random distribution and termed as episodic thickness variation of cycles along the section and frequency of sand and or silt rich cycle types are used to interpret systems tracts within the sequences

petroleum geology of the black sea abstract the black sea comprises two extensional basins formed in a back arc setting above the northward subducting tethys ocean close to the southern margin of eurasia the two basins coalesced late in their post rift phases in the pliocene forming the present single depocentre the western black sea was initiated in the aptian when a part of the moesian platform now the western pontides of turkey began to rift and move away to the south east the eastern black sea probably formed by separation of the mid black sea high from the shatsky ridge during the palaeocene to eocene subsequent to rifting the basins were the sites of mainly deep water deposition only during the late miocene was there a major sea level fall leading to the development of a relatively shallow lake most of the margins of the black sea have been extensively modified by late eocene to recent compression associated with closure of the tethys ocean gas chromatography mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the black sea can be explained by generation from an oil prone source rock of most probably late eocene age although a wider age range is possible in the basin centres burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post rift basin a palaeozoic source rock may have generated gas condensate in the gulf of odessa in bulgarian waters the main plays are associated with the development of an eocene foreland basin kamchia trough and in extensional structures related to western black sea rifting the latter continue into the romanian shelf where there is also potential in rollover anticlines due to gravity sliding of neogene sediments in the gulf of odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures small gas and oil discoveries around the sea of azov point to further potential offshore around the central azov high in offshore russia and georgia there are large culminations on the shatsky ridge but these are mainly in deep water and may have poor reservoirs there are small compressional structures off the northern turkish coast related to the pontide deformation these may include eocene turbidite reservoirs the extensional fault blocks of the andrusov ridge mid black sea high are seen as having the best potential for large hydrocarbon volumes but in 2200 m of water

low frequency currents from deep moorings in the southern bay of bengal abstracthigh resolution currents and hydrographic fields were measured at six deep water moorings in the southern bay of bengal bob by the naval research laboratory as part of an international effort focused on the dynamics of the indian ocean currents temperature and salinity were sampled over the upper 500 m for 20 months between december 2013 and august 2015 one of the major goals is to understand the space time scales of the currents and physical processes that contribute to the exchange of water between the bob and the arabian sea the observations captured southwest and northeast monsoon currents seasonally varying large eddies including a cyclonic eddy the sri lanka dome sld and an anticyclonic eddy southeast of the sld the observations further showed intraseasonal oscillations with periods of 30 70 days near inertial currents and tides monthly averaged velocities commonly exceeded 50 cm s 1 near the surface and extreme velocities exceeded 150 cm s 1 during the southwest monsoon ti

facies cycles and controls on the evolution of a keep up carbonate platform kimmeridgian swiss jura during the late jurassic accelerated ocean floor spreading and associated sealevel rise were responsible for a worldwide transgression which reached its maximum in the late kimmeridgian in many western european basins this major sea level rise led to the formation of marly and condensed sections in the swiss jura however a shallow carbonate platform kept growing and only subtle changes in the stratigraphic record suggest an increasingly open marine influence field observations and thin section analyses reveal that the central swiss jura was at that time occupied by tidal flats and by more or less open marine lagoons where shoals and bioherms developed the evolution through time of sedimentary facies and bed thicknesses permits the definition of small medium and large scale depositional sequences the diagnostic features of these sequences are independent of scale and seem largely controlled by the kimmeridgian second order transgression a high resolution sequencestratigraphic correlation with biostratigraphically well dated hemipelagic and pelagic sections in the vocontian basin in france reveals that i the most important increase in accommodation recorded in the kimmeridgian of the central swiss jura occurs in the eudoxus ammonite zone late kimmeridgian and corresponds to the second order maximum flooding recognized in many sedimentary basins ii the small and medium scale sequences have time durations corresponding to the first and second orbital eccentricity cycle i e 100 and 400 ka respectively suggesting that sedimentation on the platform and in the basin was at least partly controlled by cyclic environmental changes induced by insolation variations in the milankovitch frequency band the comparison of the high resolution temporal framework defined in the swiss jura and vocontian basin with the sequencestratigraphic interpretation realized in other western european basins shows that the large scale sequence boundaries defined in the kimmeridgian of the swiss jura appear in comparable biostratigraphic positions in most western european basins discrepancies that occur are probably because of local or regional tectonics

tectonic and eustatic control on a mixed siliciclastic carbonate platform during the late oxfordian kimmeridgian la rochelle platform western france boreal and tethyan realms of western europe present significant sedimentological paleontological and stratigraphic differences the purpose of this study is to constrain regional versus global controls on the dynamics of a sedimentary system located at the interface of these two realms in order to better understand the origin of their differences detailed sedimentological palynofacies and calcareous nannofossil analyses were performed on two sections from the la rochelle platform western france the pas section includes part of the late oxfordian and early kimmeridgian and the rocher d yves section is assigned to the late kimmeridgian they correspond to monotonous marl argillaceous limestone alternations limestones are essentially mudstones with echinoderms bivalves and foraminifera that suggest low energy open marine conditions highly bioclastic and or peloidal deposits occur commonly and show wackestones to wacke pack grainstones textures these deposits indicate frequent high energy events and are interpreted as storm deposits marls dominate in the most proximal depositional environments while calcareous deposits are more important in more distal environments the rocher d yves section is globally more marly than the pas section suggesting a more proximal setting palynofacies are dominated by woody particles suggesting shallow water proximal depositional environments calcareous nannofossils are ascidian spicules coccoliths and schizospheres watznaueria britannica dominate calcareous nannofossil assemblages in the pas section the rocher d yves assemblages are quasi exclusively composed of cyclagelosphaera margerelii and indicate more proximal paleoenvironments than those of the pas section different orders of depositional sequences are defined with sequence boundaries corresponding to the most rapid relative sea level falls they are hierarchically stacked and correlate on the basis of ammonite zones with the sequences of contemporaneous sections from tethyan and boreal realms the stacking pattern of these sequences suggests an orbital control on sedimentation small medium and large scale sequences correspond to precession 20 ky cycles and to 100 ky and 400 ky eccentricity cycles respectively the elementary sequences have durations shorter than 20 ky the kimmeridgian was a period of global sea level rise that ended in the late kimmeridgian more proximal depositional environments in the rocher d yves section late kimmeridgian than in the pas section early kimmeridgian imply a progradation of the la rochelle platform during the kimmeridgian this progradation resulted from a slowdown of the subsidence in the aquitaine basin during the kimmeridgian corresponding to the first steps of atlantic ocean opening high frequency cycles on the la rochelle platform formed in sync with milankovitch orbital cycles while tectonics controlled the formation of the low frequency cycles

source mechanism of the bartin earthquake of september 3 1968 in northwestern turkey evidence for active thrust faulting at the southern black sea margin abstract the bartin earthquake of september 3 1968 is the strongest instrumentally recorded earthquake to occur along the black sea margin in northwestern turkey the source mechanism of the bartin earthquake as determined in this study from long period p wave first motions and from the inversion of p and sh waves indicates thrust faulting with a strike of 28 dip of 38 and rake of 80 the average centroid depth is 4 km and the seismic moment is 3 9 10 25 dyn cm the bartin earthquake provides the first evidence for active thrust faulting at the southern margin of the black sea the black sea has probably evolved as a back arc basin resulting from the northward subduction of tethys seismicity fault plane solutions and other geophysical data suggest that at the present time the black sea is closing under north south compression