high resolution record of environmental changes and tephrochronological markers of the last glacial holocene transition at lake lautrey jura france this paper presents the results of a multiproxy investigation including volume magnetic susceptibility mineral and pollen analyses of late glacial sediments from lake lautrey jura france small scale lithological variations have been identified with high stratigraphic resolution in order to establish lithostratigraphic correlations between cores measurements combined with mineralogical analyses provide information on past sedimentary processes this combined approach reflects major changes in terrestrial habitats and soil processes which may relate to the climatic events characterising the late glacial climatic warming and cooling phases during warm intervals the record indicates increased lake productivity via carbonate precipitation and decreased input of detrital material in contrast cooler intervals show reduced lake productivity catchment area instability and increased detrital inputs several short interruptions in reforestation and in soil stabilisation can be identified and linked with abrupt colder events occurring through the bolling a general trend of warming is recorded from the coldest part of the younger dryas three tephra layers were also detected the mineral composition analyses show that the upper tephra layer corresponds to the laacher see eruption eifel germany while the lower ones may relate to the volcanic activity of the chaine des puys massif central france around 13 000 cal yr bp these two events recognised for the first time outside the massif central region may provide additional chronostratigraphic markers for the late glacial sedimentary records of the jura mountains and northern alps copyright 2004 john wiley sons ltd

ocean wave integral parameter measurements using envisat asar wave mode data an empirical algorithm to retrieve integral ocean wave parameters such as significant wave height swh mean wave period and wave height of waves with period larger than 12 s h12 from synthetic aperture radar sar images over sea surface is presented the algorithm is an extension to the envisat advanced sar asar wave mode data based on the cwave approach developed for ers 2 sar wave mode data and is thus called cwave env cwave for envisat calibrated asar images are used as the only source of input without needing prior information from an ocean wave model wam as the standard algorithms used in weather centers this algorithm makes sar an independent instrument measuring integrated wave parameters like swh and mean wave period to altimeter quality a global data set of 25 000 pairs of asar wave mode images and collocated reanalysis wam results from the european centre for medium range weather forecasts ecmwf is used to tune cwave env model coefficients validation conducted by comparing the retrieved swh to in situ buoy measurements shows a scatter index of 0 24 and 0 16 when compared to the ecmwf reanalysis wam two case studies are presented to evaluate the performance of the cwave env algorithm for high sea state a north atlantic storm during which swh is above 18 m as observed by sar and radar altimeter simultaneously is analyzed for an extreme swell case that occurred in the indian ocean the potential of using swh measurements from asar wave mode data derived by the cwave env algorithm is demonstrated

structural grain mud volcanoes and other features on the barbados ridge complex revealed by gloria long range side scan sonar abstract a long range side scan sonar survey of the broad band of deformed sediments east of the antilles volcanic arc has revealed the detailed structural trends of folds and reverse faults or thrusts in plan view for the first time the prevalent trend lies substantially parallel with the arc and is simplest near to the deformation front at the eastern edge of these deformed sediments these trends are interrupted locally by more or less transverse zones of disturbance associated with ridges in the oceanic basement that are obstructing the relative eastward movement of the deformation front local rough surfaced mounds interpreted as mud volcanoes underlain by diapirs are common and occur much further to the north than the mud diapir field already described near trinidad only one large sediment slide has been identified

modelling waves and surges during the 1953 storm waves and sea levels have been modelled for the storm of 31 january 1 february 1953 problems in modelling this event are associated with the difficulty of reconstructing wind fields and validating the model results with the limited data available from 50 years ago the reconstruction of appropriate wind fields for surge and wave models is examined the surges and waves are reproduced reasonably well on the basis of tide gauge observations and the sparse observational information on wave heights the maximum surge coincided closely in time with tidal high water producing very high water levels along the coasts of the southern north sea the statistics of the 1953 event and the likelihood of recurrence are also discussed both surge and wave components were estimated to be approximately 1 in 50 year events the maximum water level also occurred when the offshore waves were close to their maximum the estimation of return period for the total water level is more problematic and is dependent on location a scenario with the 1953 storm occurring in 2075 accounting for the effects of sea level rise and land movements is also constructed suggesting that sea level relative to the land could be 0 4 0 5 m higher than in 1953 in the southern north sea assuming a rise in mean sea level of 0 4 m

tectonic controls of the right lateral burro negro tear fault on paleogene structure and stratigraphy northeastern maracaibo basin the northeastern maracaibo basin in western venezuela was deformed by paleogene thrusting and an associated tear fault burro negro right lateral strike slip fault zone related to paleogene oblique collision between the caribbean and south american plates two different tectonic models have been previously proposed for the thick paleogene depocenter located along the northeastern margin of the maracaibo basin the first model proposes that the depocenter is a foreland basin controlled by southwestward directed overthrusting during a late paleocene middle eocene oblique collision between the caribbean and south american plates the second model supported by data presented in this study proposes that the asymmetric paleogene maracaibo sedimentary wedge was controlled by strike slip displacement along a right lateral tear fault separating southeast directed thrust sheets to the east lara nappes from a more stable platform area to the west maracaibo basin regional seismic lines recorded to 5 s two way traveltime reveal the structure of the asymmetric paleogene depocenter in the northeastern part of the maracaibo basin the approximately 100 km 62 mi long burro negro fault is a right lateral strike slip fault separating less deformed inner to outer shelf rocks of the western maracaibo basin from highly deformed deep marine rocks of the eastern maracaibo basin seismic lines northeast of the burro negro fault zone show elongate subsurface basins bounded by partially inverted reverse and strike slip faults filled with about 3 km 1 8 mi of oligocene and miocene clastic marine sedimentary rocks structural highs of eocene rocks are characterized at depth on seismic reflection lines by chaotic seismic reflections that underlie the more coherently stratified oligocene and miocene subbasins we interpret these structural highs as steeply dipping fault zones and shale diapirs activated during eocene oligocene oblique plate convergence the geology and overall structural configuration of the northeastern maracaibo basin and the burro negro fault zone support its origin as a right lateral tear fault in our model the burro negro fault zone accommodated southeastward migration of the thrust front in the deep water area east of the fault in the present day falcn region the paleogene clastic wedge of the maracaibo basin exhibits many common features of a classic foreland basin including onlap onto an arch or forebulge located near the center of the present day lake maracaibo this paleogeographic coincidence of the burro negro fault zone and the maracaibo shelf edge suggests that the paleotrend of the south american passive margin prior to collision was serrated in map view west to east migration of the caribbean south america oblique collision formed progressively younger parallel tear faults to the east of the maracaibo basin that may have formed by the same tectonic process as the burro negro fault zone

a genetic model of hydrocarbon derived carbonate chimneys in shelfal fine grained sediments the enza river field northern apennines italy abstract methane derived authigenic carbonate mdac concretions have been recently exposed in the pleistocene argille azzurre fm outcropping along the enza riverbanks northern apennines foothills italy the relations between the sediment deposition the coeval tectonic deformation and the mdac concretions have been investigated to unravel the mechanism of methane migration through the sediments and the processes leading to mdac occurrence the biogenic methane responsible for the formation of mdac chimneys and slabs has been generated in the organic rich pliocene sediments located in the po plain subsurface the gas migrated up dip towards the northern apennines foothills the mdac cements are mainly composed of dolomite whose precipitation requires thousand years and the absence of so 4 in the pore fluids according with the sedimentation rates of the mdac hosting pleistocene succession the sulphate methane transition zone migrated upwards faster than time required for dolomite precipitation therefore the connate water migrating together with the methane could have acted as second dic source allowing the mdac formation also in the methane rich zone

identification and significance of a visible basalt rich vedde ash layer in a late glacial sequence on the isle of skye inner hebrides scotland this paper reports the discovery of a visible tephra horizon of late glacial age from the site of loch ashik in the isle of skye the inner hebrides scotland although the tephra shards have a bimodal geochemical composition identical to that of the vedde ash a well known marker horizon within late glacial sequences the horizon at ashik is dominated by basaltic shards and devitrified tephra shards giving the layer its characteristic black colour only rhyolitic shards have previously been reported from vedde ash horizons in the british isles this new evidence raises some important questions about the factors that govern the distribution and accumulation of basaltic tephra and about the methods used to detect ash shards in basins distal to centres of volcanic activity copyright 2001 john wiley sons ltd

a new estimate of global methane flux from onshore and shallow submarine mud volcanoes to the atmosphere a new estimate of global methane emission into the atmosphere from mud volcanoes mvs on land and shallow seafloor is presented the estimate considered a lower limit is based on 1 new direct measurements of flux including both venting of methane and diffuse microseepage around craters and vents and 2 a classification of mv sizes in terms of area km2 based on a compilation of data from 120 mvs the methane flux to the atmosphere is conservatively estimated between 6 and 9 mt y 1 this emission from mvs is 3 6 of the natural methane sources and is comparable with ocean and hydrate sources officially considered in the atmospheric methane budget the total geologic source including mvs seepage from seafloor microseepage in hydrocarbon prone areas and geothermal sources would amount to 35 45 mt y 1 the authors believe it is time to add this parameter in the intergovernmental panel on climate change official tables of atmospheric methane sources

a 7000 year environmental history and soil erosion record inferred from the deep sediments of lake pavin massif central france a 14 m long sedimentary sequence core pav12 was collected in the deepest part of lake pavin a maar lake located in the french massif central the pav12 sedimentary sequence documents the lake s environmental evolution since its formation 7000 years ago the relationships between the catchment s vegetation cover erosion processes and changes in trophic status were shown using a multi proxy characterization of mineral and organic fractions supported by palynological data the record shows a succession of lithological units starting at the base with volcanoclastic material corresponding to the early stage of lake pavin the deposition of organic rich and diatomaceous sedimentary units above volcanoclastic material indicates an evolution toward a pristine lacustrine state the late holocene environmental history of this lake is marked by two tipping points reflecting major environmental disturbances at ca 4000 cal bp and after the deposition of erosive mass wasting deposits mwds at 1350 cal bp ce 600 and 650 cal bp ce 1300 the upper unit of core pav12 which corresponds to the past 700 years indicates that one of these mwds was likely the driving force behind a major limnological change marked by a shift in redox sensitive elements i e current meromictic lacustrine state the palynological diagram indicates a forested catchment where woodland clearances and agro pastoral activities have remained limited except over the last 700 years these findings suggest restricted human impact within the watershed compared to other regional archives the reconstruction of the lake pavin erosion record determined from titanium and red amorphous particle fluxes highlights phases of enhanced erosion at ca 6 5 5 5 4 1 3 8 3 5 2 8 2 6 1 6 1 4 cal kyr bp and during the little ice age lia a comparison between this erosion record palaeoenvironmental archives from western europe and palaeoclimatic data supports an atlantic signal driving precipitation patterns over lake pavin at centennial to millennial timescales the influence of local human activities even on a small scale cannot be completely discounted as their impact on erosional processes may be amplified in a steep catchment such as that found in lake pavin

regional controls on geomorphology hydrology and ecosystem integrity in the orinoco delta venezuela interacting river discharge tidal oscillation and tropical rainfall across the 22 000 km2 orinoco delta plain support diverse fresh and brackish water ecosystems to develop environmental baseline information for this largely unpopulated region we evaluate major coastal plain shallow marine and river systems of northeastern south america which serves to identify principal sources and controls of water and sediment flow into through and out of the orinoco delta the regional analysis includes a summary of the geology hydrodynamics sediment dynamics and geomorphic characteristics of the orinoco drainage basin river and delta system because the amazon river is a major source of sediment deposited along the orinoco coast we summarize amazon water and sediment input to the northeastern south american littoral zone we investigate sediment dynamics and geomorphology of the guiana coast where marine processes and holocene history are similar to the orinoco coast major factors controlling orinoco delta water and sediment dynamics include the pronounced annual flood discharge the uneven distribution of water and sediment discharge across the delta plain discharge of large volumes of water with low sediment concentrations through the rio grande and araguao distributaries water and sediment dynamics associated with the guayana littoral current along the northeastern south american coast inflow of large volumes of amazon sediment to the orinoco coast development of a fresh water plume seaward of boca grande disruption of the guayana current by trinidad boca de serpientes and gulf of paria and the constriction at boca de serpientes

yangtze delta eastern china 2 late quaternary subsidence and deformation abstract late quaternary deposits examined on high resolution seismic profiles provide evidence of recent subsidence of the outer yangtze delta in the east china sea deformed late pleistocene strata and mud diapirs tilted bedding and gas deformed structures in holocene sequences record remobilization of underconsolidated sediment within and adjacent to the yangtze depocenter deformation types and their specific position relative to the depocenter record displacement of sediment as a result of quaternary overburden and probable compaction and deep seated tectonic motion the configuration of depositional sequences demonstrates that subsidence in the outer yangtze delta has continued from the late pleistocene to the present

teleconnection pattern influence on sea wave climate in the bay of biscay the potential modification of hydrodynamic factors such as waves is a source of concern for many coastal communities because of its potential effect on shoreline evolution in the northern atlantic swell is created by storm winds that cross the atlantic following west east tracks these tracks are shifted more southward or northward depending on the season and on recurring large scale atmospheric pressure anomalies also called teleconnection patterns this study investigates the trends of sea wave patterns in the bay of biscay and relates their interannual variability to teleconnection patterns sea wave parameter time series from the 40 yr european centre for medium range weather forecasts

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

structure and deformation history of the northern range of trinidad and adjacent areas conflicting models have been proposed for both the evolution of northern south america and the neotectonics of the south caribbean plate boundary zone the trinidadian portion of the margin is particularly controversial but surprisingly it has been little studied we present a structural analysis of trinidad s northern range pertinent updates of the island s stratigraphy and sedimentology and new zircon fission track age determinations and use them to constrain trinidad s geologic history and to better understand the controlling tectonic processes in our interpretation trinidad s three e ene striking ranges which are separated by late neogene recent depocenters expose 1 the northern range group generally greenschist metamorphosed upper jurassic to cretaceous north facing continental slope sediments of the northern range deposited on the northern south american passive margin 200 400 km to the wnw and 2 the trinidad group cretaceous paleogene shelf slope sediments of the central and southern trinidad deposited less than 100 km wnw of their present location a small allochthon composing the sans souci group cretaceous tholeiitic volcaniclastic basaltic and gabbroic rocks sans souci formation and sediments toco formation now in the northeastern northern range has been transported hundreds of kilometers from the west with the caribbean plate despite earlier references to cretaceous orogenesis all deformation in trinidad is of cenozoic age the first deformation in the northern range d1 formed north vergent nappes and induced greenschist metamorphism probably in the late eocene or oligocene the nappes developed either by the underthrusting of the proto caribbean crust beneath south america due to convergence between north and south america or as gravity slides caused by oversteepening induced by this convergence and or the passage of the caribbean plate s peripheral bulge and arrival of its foredeep northern range d2 deformation is south vergent and represents the incorporation of northern range metasediments into the caribbean accretionary prism the transition to d3 brittle transpressive right lateral strike slip faulting is interpreted to be due to the uplift and east southeastward transpressive emplacement of northern range caribbean prism rocks onto the south american stepped shelf this emplacement formed the miocene transpressive thrust belts and foreland basin in central and southern trinidad in the final phase of northern range deformation d4 e w normal faults and shear zones and conjugate nnw sse and ne sw normal faults developed and displacement on preexisting e w right lateral strike slip faults continued the 11 ma northern range zircon fission track ages suggest rapid uplift from the late miocene to recent late miocene subsidence of the tobago platform immediately to the north of the northern range and greater than 3 km of normal down to the north displacement indicated for the north coast fault zone separating the northern range and tobago platform leads us to postulate that the rapid uplift of the northern range was in response to the northward detachment of the tobago platform from above the northern range along the north dipping transtensional north coast fault zone this late miocene change in deformation style can be explained by a change from caribbean south american right lateral transpression to right lateral strike slip generally striking 080 this has generally induced a component of extension on pre existing faults striking at greater than 080 and a component of compression on faults striking at less than 080

the recent increase in north atlantic wave heights the nature and causes of the recent increase in north atlantic wave heights are explored by combining a numerical hindcast with a statistical analysis the numerical hindcast incorporates a 10 yr history 1980 89 of north atlantic twice daily wind analyses to generate a monthly averaged significant wave height swh history the hindcast compares favorably with published monthly averaged swh observations the link between modelgenerated wintertime monthly swh and monthly averaged sea level pressure slp data is determined by means of a canonical correlation analysis cca within the analysis domain most of the variance in swh and slp is captured by two pairs of joint patterns the leading pair consists of a slp dipole resembling the north atlantic oscillation nao and a swh dipole in spatial quadrature relation to it using the cca results an extended statistical hindcast of monthly wave fields is generated from sea level pressure data and used to quantitatively estimate the systematic increase in wave heights since the 1960s it is shown that an increasing trend in swh at several northeast atlantic locations since 1960 or so is related to the systematic deepening of the icelandic low and intensification of the azores high over the last three decades the analysis suggests that wave height south of 408n has decreased during the same period

environmental and climatic changes in the jura mountains eastern france during the lateglacial holocene transition a multi proxy record from lake lautrey this paper presents a multi proxy reconstruction of the climatic and environmental changes during the last glacial interglacial transition as recorded by a sediment sequence from lake lautrey jura eastern france this reconstruction is based on analysis of pollen chironomid organic matter oxygen isotope mineralogical magnetic susceptibility and inferred lake level data at a high temporal resolution the chronology is derived using ams radiocarbon dates the position of the laacher see tephra lst and of correlation between the lautrey and grip oxygen isotope records this data set reveals a detailed sequence of environmental changes in the jura mountains from greenland stadial 2a to the early holocene biotic and abiotic indicators allow the recognition of major abrupt changes associated with the gs 2a gi 1e gi 1a gs 1 and gs 1 preboreal transitions and other minor fluctuations related to the cold events gi 1d gi 1b and the preboreal oscillation pbo they also suggest additional cooling spells at ca 14 550 and 14 350 cal yr bp intra bolling cold periods at ca 13 500 and ca 12 700 cal yr bp just before the gs 1 onset and at ca 11 350 cal yr bp just before the pbo as well as an intriguing brief warming episode within gs 1 at ca 12 080 cal yr bp summer temperature increased by ca 5 c at the start of gi 1e and by 1 5 3 c at the holocene onset while it decreased by ca 3 4 c at the beginning of gs 1 major changes in local hydrology and in seasonality appear to be also associated with the gs 2a gi 1e gi 1a gs 1 and gs 1 preboreal transitions pollen and abiotic indicators suggest a greater sensitivity of the vegetation cover to climatic oscillations during the first part of the lateglacial interstadial than during the second part after ca 13 700 cal yr bp when a closed forest had been restored in this area by contrast the restoration of forest cover took less than 300 yr after the end of gs 1 at the beginning of gi 1e and gs 1 no lag occurs within the sampling resolution of 20 50 yr in the responses of aquatic chironomids and terrestrial pollen ecosystems while at the onset of the holocene the response of the vegetation appears slightly delayed in comparison with that of the chironomid community finally the recognition of two successive tephra layers which were deposited just before the lst at ca 12 950 cal yr bp and which originated from le puy de la nugere massif central france provides an additional tephrochronological tool for correlation between lateglacial european sequences

feldspar composition as an efficient tool for tephra identification a case study from holocene and lateglacial lacustrine sequences jura france four volcanic ash layers have been identified in lateglacial and holocene sediments from three lakes in the jura mountains the vasset tephra and the nugere tephra chaine des puys the vedde ash icelandic and the laacher see tephra lst eifel some of these are invisible to the naked eye and have been detected by magnetic susceptibility measurements and x ray fluorescence analysis these layers are composed of rare glass shards in association with feldspars and pyroxenes in lacustrine carbonated sediment formations where glass shards are scarce and altered the geochemical analysis of feldspar composition appears to be an effective substitute tool for characterization of the tephra the identification of the middle lst c phase in our sites modifies the currently known spatial distribution of the lst eifel germany the identification of two tephras from the chaine des puys volcanic sources in jurassian sites the trachytic vasset tephra and the trachy andesitic nugere tephra provides new time markers for the early holocene and late allerod respectively thereby enhancing our knowledge of their distribution throughout western europe more generally these results confirm the major scientific value of lacustrine sequences from the jura region for cryptotephra research especially within late quaternary palaeoenvironmental studies

measurements of the offshore wave climate around the british isles by satellite altimeter satellite altimetry gives a new perspective on ocean wave climate measurements around the british isles show a strong seasonality with exceptionally large average wave heights to the west and north of the british isles in the winter furthermore the interannual variability of winter wave climate is very high most of this variability can be described by a strong linear dependence on the north atlantic oscillation nao index this relationship may largely explain observations of increasing wave heights in the northeastern atlantic and northern north sea during the latter decades of the 20th century coincident with a long term rise in the nao

role of wave forcing storms and nao in outer bar dynamics on a high energy macro tidal beach abstract outer sand bar dynamics on a high energy macro tidal beach were investigated using long term multi year field datasets of intertidal morphology and offshore bathymetry utilising a 15 year time series of argus video images five distinct outer bar types were identified mega rip longshore crescentic crescentic attached and welded the most common classification was crescentic attached with the outer bar oscillations being out of phase with the inner bar oscillations as would be expected for the shore normal wave approach at this site the outer bar had a typical amplitude of 0 5 1 m and a longshore wavelength of 600 m changes in outer bar morphology were related to measured and modelled nearshore wave data however the outer bar morphology changed over a much longer timescale monthly to annual than the daily to weekly variations in wave height and period an extended duration of energetic wave action was required to bring about an upstate bar transition to the longshore or mega rip state where the bar then remained arrested for a significant amount of time requiring several months of low wave conditions to induce a down state transition through crescentic to welded this slow morphological response is explained by extended relaxation times attributed to the large tidal range at the study site where the outer bar morphology is only active for part of the tidal cycle several hours around low tide the configuration and position of the outer bar were related the more upstate downstate bar types being associated with a more offshore onshore bar position the detrended outer bar position was significantly related to a forcing term based on wave power and disequilibrium of the dimensionless fall velocity with offshore onshore bar migration occurring when wave conditions were more less energetic that the antecedent conditions the upstate end member longshore or mega rip was attained sometime during the winter months for 14 out of the 16 years of monitoring the outer bar remained attached to the low tide shoreline over the winter 2005 2006 and 2010 2011 these two winters with incomplete upstate cycles were characterised by the lowest winter wave conditions and negative winter north atlantic oscillation nao indices suggesting that the winter nao is correlated with both beach state and nearshore bar configuration

waves and climate change in the north east atlantic wave height in the north atlantic has been observed to increase over the last quarter century based on monthly mean data derived from observations empirical models have linked a large part of this increase in wave height with the north atlantic oscillation wave models provide a tool to study impacts of various climate change scenarios and investigate physical explanations of statistical results in this case we use a wave model of the ne atlantic model tests were carried out using synthetic wind fields varying the strength of the prevailing westerly winds and the frequency and intensity of storms the location of storm tracks and the storm propagation speed the strength of the westerly winds is most effective at increasing mean and maximum monthly wave height the frequency intensity track and speed of storms have little effect on the mean wave height but intensity track and speed significantly affect maximum wave height

mud volcanism on the mediterranean ridge initial results of ocean drilling program leg 160 drilling during ocean drilling program leg 160 april may 1995 revealed important new evidence concerning the internal composition depositional processes and age of two mud volcanoes within the mediterranean ridge accretionary complex holes were drilled at ca 2000 m water depth on the crest areas across the flanks of the mud volcanoes and onto adjacent deep sea sediments the main depositional units forming the flanks of both mud volcanoes are debris flows mud breccias composed of a volumetrically dominant mud matrix containing clasts of mainly clay mudstone siltstone sandstone and limestone more variable muddy silty and sandy sediments were recovered from the crestal areas of both volcanoes the lowest mud volcano units drilled include well sorted medium to coarse grained sediments mainly composed of clay that were deposited partly by turbidity currents the mud volcano sediments are associated with background deep sea sediments that allow dating by using microfossils the milano mud volcano is at least 1 75 ma and is apparently now dormant and the napoli mud volcano started prior to or during 1 5 1 2 ma and is currently active pore fluids at napoli and to a lesser extent at milano indicate the presence of halite of presumed latest miocene age beneath the volcanoes hydrocarbon gas is venting from the crest of the napoli mud volcano and gas was also detected on the crest of the milano mud volcano methane hydrates clathrates are also inferred to exist beneath the crest of the milano mud volcano the mud volcanoes are located above a shallowly dipping subduction zone in an area where the accretionary complex is apparently being thrust northward over a backstop of continental crust related to initial collision of the african and eurasian plates mud volcanism may have begun when backthrusting punctured a seal of latest miocene evaporites allowing the escape of overpressured materials

mesoscale evolution of a headland bay beach rotation processes abstract the morphology change of a headland bay beach tenby west wales gr 212200 198599 has been analysed over a mesoscale timeframe 1830 2009 gis cross shore profiles off shore wave climate have been utilised to assess the role of atmospheric variability on long term shoreline change previous studies have suggested that plan form change seen in recent times has been caused by closure of ritec valley estuary circa 1855 and whilst admittedly closure did have an initial effect with northerly dune field migration and reductions in inter tidal and nearshore estuary flushing this study suggests that climatic variations also contribute to evolution of this bay mesoscale analysis qualitatively highlights two distinct time periods of plan form evolution characterised by total reversals in trend that take place around 1919 more recent bay rotation about a stable central sector is shown quantitatively the southern sector shows progressive retreat r2 0 93 whilst the northern sector is shown to advance r2 0 56 points of rotation show steady migration northwards as retreat is encountered within the south sector r2 0 79 which confirms that the bay is still evolving on a decadal level correlation can be found between positive nao index values and beach level and volume reductions based on a visually active beach profile r2 0 44 and 0 53 respectively whilst normalised wave height variability is also closely linked with index change t 0 952 df 82 p 0 05 over a similar timeframe positive index values result in stormier south westerly winds 180 270 where it is found that 54 of high winds emanate from this quadrant further correlation is found between these winds and nao index r2 0 47 winds from this direction produce waves that diffract and refract around giltar headland and off shore caldey island that induce a south to north movement of sediment increasing southerly shoreline retreat and conversely northerly advance qualitative observations of hind casts produced using decadal analysis regression equations and mesoscale nao data suggest that the atmospheric variation is a contributory factor in bay evolution similar scenarios are likely to exist at other locations therefore assessments should be repeated more widely to develop appropriate management strategies

interpretation of recent antarctic sea ice variability 1 trends in the satellite derived antarctic sea ice concentrations 1979 2002 show pronounced increase decrease in the central pacific sector bellingshausen western weddell sector by 4 10 per decade confidence levels for these regional trends exceed 95 positive polarities of the antarctic oscillation aao lead to more less ice in the eastern ross amundsen sector bellingshausen northern weddell sector which are qualitatively opposite to the impacts of positive polarities of the el nino southern oscillation enso the mechanisms responsible for the covariability between the ice and the a aao and b enso are demonstrated over the last 24 years a positive aao trend and a slightly negative enso trend produce a spatial pattern of ice changes similar to the regional ice trends however the magnitude of the ice changes associated with the aao and enso is much smaller than the regional ice trends more local or less understood large scale processes should be investigated for the explanations

two faces of enso induced surface waves during the tropical cyclone season abstract the response of the wave climate to tropical cyclones tcs is investigated using the significant wave height swh observed from satellites and the wavewatch iii ww3 model tropical cyclone wind generates local waves wind seas under the tc and longer period waves swells that propagate long distances the genesis location intensity and frequency of tropical cyclones over the global ocean are strongly affected by the phases of the el nino southern oscillation enso it is shown that the interannual variation of global ocean surface waves in the subtropics during summer is dominated by enso related tc activity in particular in the subtropical western north pacific the wind power is stronger in the tc season before an el nino and weaker before a la nina these enso related tc variations are shown through composite and empirical orthogonal function analyses as well as modeling to dominate the spatial distribution and temporal variation of the swh over the western north pacific the model confirms that longer period waves swells are driven into northern south china sea toward japan in mid latitudes and toward the central pacific along the equator due to enso related tc activities the wind power and swh over the subtropical western north pacific lead and regress well with the enso index suggesting that they may potentially serve as useful enso predictors

varve microfacies and varve preservation record of climate change and human impact for the last 6000 years at lake tiefer see ne germany the holocene sediment record of lake tiefer see exhibits striking alternations between well varved and non varved intervals here we present a high resolution multi proxy record for the past 6000

mud volcanoes in the alboran sea evidence from micropaleontological and geophysical data during the basacalb ttr9 cruise of the r v professor logachev 1999 two mud volcanoes called marrakech and granada were discovered in the southern sector of the mud diapir province in the west alboran basin wab this paper presents micropaleontological and geophysical data on these mud volcanoes from gravity core samples sidescan sonar okean images and high resolution seismic lines mud breccia recovered from the granada mud volcano is matrix supported with well consolidated clasts of limestone marlstone claystone siltstone sandstone and mudstone whereas mud breccia from the marrakech mud volcano contains unconsolidated clasts the mud breccia matrix contains abundant miocene calcareous nannofossils cn together with pliocene pleistocene species and reworked late cretaceous and paleocene eocene species cn dating indicates that clasts in the mud breccia derive from late cretaceous paleocene eocene and probable miocene sediments these data suggest that the mud diapirs and mud volcanoes in the wab can be derived from the olistostromes of unit vi the basal stratigraphic sequence in the alboran sea basin unit viconsists of lower miocene sediments that incorporated late cretaceous and paleocene eocene materials and basement derived rock fragments the mud volcanic deposits are covered by a thin drape of pelagic marls suggesting that these two volcanoes are currently inactive structures determined on highresolution seismic profiles across mud volcanoes and surrounding diapirs correspond to the late stage pliocene toquaternary diapir development this stage is thought to have developed during a compressional tectonic setting that produced folding and wrench tectonics throughout the basin mud ascent at that time resulted in active diapirism and mud volcanoes on the seafloor 2002 elsevier science b v all rights reserved

tephrochronology and the extended intimate integration of ice core marine and terrestrial records event stratigraphy 8 128 ka b2k the comparison of palaeoclimate records on their own independent timescales is central to the work of the intimate integrating ice core marine and terrestrial records network for the north atlantic region an event stratigraphy has been established from the high precision greenland ice core records and the integrated gicc05 chronology this stratotype provides a palaeoclimate signal to which the timing and nature of palaeoenvironmental change recorded in marine and terrestrial archives can be compared to facilitate this wider comparison without assuming synchroneity of climatic change proxy response intimate has also focussed on the development of tools to achieve this in particular the use of time parallel marker horizons e g tephra layers volcanic ash coupled with the recent temporal extension of the greenland stratotype as part of this special issue we present an updated intimate event stratigraphy highlighting key tephra horizons used for correlation across europe and the north atlantic we discuss the advantages of such an approach and the key challenges for the further integration of terrestrial palaeoenvironmental records with those from ice cores and the marine realm

a 150 year record of coastline dynamics within a sediment cell eastern england abstract coastal sediment cells reflect processes operating at a range of scales but it is the medium spatial and temporal scales decades to centuries that are of greatest interest for coastal management this paper focuses on coastline position change within a single sediment cell over 150 years where the geomorphology includes cliffs beaches and saltmarshes the focus is the east coast of england from flamborough head to gibraltar point although the updrift sector of this sediment cell has been studied for well over a century the downdrift sector has attracted significantly less attention using topographic profiles bathymetric profiles aerial photographs and historical maps we mapped coastline erosion and accretion using the digital shoreline analysis system dsas and calculated volumetric changes for different morphometric units rapid erosion of the updrift holderness cliffs has been counterbalanced with accretion on beaches along the downdrift lincolnshire coast the amount of accretion in lincolnshire corresponds to around 29 of the volume of sediment eroded from holderness much of the eroded cliff material is likely to be deposited temporarily into nearshore and offshore sand banks before being redistributed by cross shore currents an exploration of storm surge impact on long term erosion and accretion rates showed no clear relationship between storm surge frequency and change in coastline position however this may be in part due to the relative timing of storm occurrence and data acquisition the jenkinson daily weather type classification was found to be a reasonable proxy for the occurrence of strong onshore winds which may offer scope for further investigation of the role of forcing factors over time periods beyond the length of the meteorological and tidal station records winter north atlantic oscillation phase was not a good indicator of storminess on the east coast of england but may be a useful proxy for quiescence

decadal wave power variability in the north east atlantic and north sea 2015 american geophysical union all rights reserved estimation of the long term behavior of wave climate is crucial for harnessing wave energy in a cost effective way previous studies have linked wave heights to the north south atmospheric pressure anomalies in the north atlantic suggesting that the wave climate fluctuates as a response to changes in zonal circulation in the atmosphere we identify changes in wave power in the north east atlantic that are strongly correlated to the dominant pressure anomalies the north atlantic oscillation nao and other modes we present a reconstructed wave power climate for 1665 2005 using a combination of known and proxy indices for the nao and other modes our reconstruction shows high interannual and multidecadal variability which makes wave energy prediction challenging this variability should be considered in any long term reliability analysis for wave energy devices and in power scheme economics

extreme wave climate variability in southern europe using satellite data 1 a time dependent generalized extreme value gev model for monthly significant wave height maxima from satellite databases is used to model the seasonal and interannual variability of the extreme wave climate throughout southern europe in order to avoid a misleading use of the maxima time series the classical extreme value model has been modified to cope with nonhomogeneous monthly observations seasonality is represented using intraannual harmonic functions in the model while interannual variability is modeled including north atlantic and mediterranean regional scale sea level pressure predictors such as the north atlantic oscillation nao the east atlantic ea or the east atlantic western russian ea wr patterns the results quantify the strong spatial variability detected in the seasonal location and scale gev parameters in general prominent zonal west east and meridional north south gradients of these location and scale parameters reveal the predominance of low pressure centers located in the nao region e g a gradient of 4 m for the location parameter and 1 5 units for the scale parameter between north south is shown in the month of september the model also quantifies the influence of regional climate patterns on extreme wave climate results show a great influence of nao and ea on the atlantic basin e g every unit of the monthly nao index explains 25 cm of the extreme wave height in the gulf of biscay and the ea index explains 20 cm while the negative phases of ea wr contribute greatly to the western mediterranean basin

trends of atlantic wave extremes as simulated in a 40 yr wave hindcast using kinematically reanalyzed wind fields abstract in this study seasonal extremes of wave height in the north atlantic are analyzed the analysis is based on a 40 yr 1958 97 numerical wave hindcast using an intensive kinematic reanalysis of wind fields changes in the ocean wave extremes are identified by performing the mann kendall test and are further related to changes in the atmospheric circulation sea level pressure by means of redundancy analysis the relationship between sea level pressure and ocean wave extremes is also used to reconstruct the seasonal wave statistics for the last century back to 1899 consistent with previous studies this high resolution atlantic wave hindcast also shows that the northeast north atlantic ocean has experienced significant multidecadal variations in the last century and it has indeed roughened in winters of the last four decades the winter wave height increases are closely related to changes in the north atlantic oscillation during the last four decades while showing trend patterns similar to

last century changes in ocean wind wave height from global visual wave data 1 centennial time series of visually observed wave height were derived from the international comprehensive ocean atmosphere data set along the major ship routes in the world ocean and homogenized they demonstrate positive trends in significant wave height over the north pacific with a maximum of 8 10 cm decade in the northeast pacific in the north atlantic and other basins significant upward changes up to 14 cm decade are observed only for the last 50 years and not for centennial records long term changes in wind wave height are closely associated with the north atlantic oscillation in the atlantic and with north pacific oscillation and el nino southern oscillation in the pacific

influence of the pacific south american modes on the global spectral wind wave climate in this study we analyse the influence of the pacific south american modes psa 1 and psa 2 on the global wind wave climate using wave data derived from a wavewatch iii global wave hindcast we apply an empirical orthogonal function analysis to daily averaged directional wave spectra to extract the two main patterns of interannual wave spectral variability these are related to changes in the wave spectral density levels variability in the wave heights and to rotations of the wave signal variability in wave direction the psa 1 mode is positively correlated with the wave height variability in the southeast pacific and negatively correlated in the indian ocean sector of the southern ocean the psa 2 mode presents a strong negative correlation with wave heights in the central south pacific moreover the psa modes are significantly correlated with changes in modelled wave direction in the south pacific region composite maps of wind anomalies during positive stages of psa 1 and psa 2 provide a compelling explanation for the observed correlation patterns the methodology applied in this study is also used to assess the influence of other climate modes on the global wind wave climate namely the southern annular mode arctic oscillation north atlantic oscillation el nino southern oscillation and the pacific north american mode while our results are consistent with previous studies we provide more clarity as to how different atmospheric modes influence the variability of specific components of the wave spectrum importantly we assess the how these climate modes would modulate the interannual variability of wave direction

variability of the winter wind waves and swell in the north atlantic and north pacific as revealed by the voluntary observing ship data this paper analyses secular changes and interannual variability in the wind wave swell and significant wave height swh characteristics over the north atlantic and north pacific on the basis of wind wave climatology derived from the visual wave observations of voluntary observing ship vos officers these data are available from the international comprehensive ocean atmosphere data set icoads collection of surface meteorological observations for 1958 2002 but require much more complicated preprocessing than standard meteorological variables such as sea level pressure temperature and wind visual vos data allow for separate analysis of changes in wind sea and swell as well as in significant wave height which has been derived from wind sea and swell estimates in both north atlantic and north pacific midlatitudes winter significant wave height shows a secular increase from 10 to 40 cm decade 1 during the last 45 yr however in the north atlantic the patterns of trend changes for wind sea and swell are quite different from each other showing opposite signs of changes in the northeast atlantic trend patterns of wind sea swell and swh in the north pacific are more consistent with each other qualitatively the same conclusions hold for the analysis of interannual variability whose leading modes demonstrate noticeable differences for wind sea and swell statistical analysis shows that variability in wind sea is closely associated with the local wind speed while swell changes can be driven by the variations in the cyclone counts implying the importance of forcing frequency for the resulting changes in significant wave height this mechanism of differences in variability patterns of wind sea and swell is likely more realistic than the northeastward propagation of swells from the regions from which the wind sea signal originates

present wave climate in the bay of biscay spatiotemporal variability and trends from 1958 to 2001 abstractclimate change impacts on wave conditions can increase the risk of offshore and coastal hazards the present paper investigates wave climate multidecadal trends and interannual variability in the bay of biscay during the past decades 1958 2001 wave fields are computed with a wave modeling system based on the wavewatch iii code and forced by 40 yr european centre for medium range weather forecasts re analysis era 40 wind fields it provides both an extended spatiotemporal domain and a refined spatial resolution over the bay of biscay the validation of the wave model is based on 11 buoys allowing for the use of computed wave fields in the analysis of mean and extreme wave height trends and variability wave height period and direction are examined for a large array of wave conditions by seasons high percentiles of wave heights different periods several trends for recent periods are identified notably an increase of summer significant wave height a southerly shift of autumn extreme wa

medium timescale beach rotation gale climate and offshore island influences abstract beach profile surveys gale climate and atmospheric variations were utilized to assess medium timescale morphological change at south sands tenby west wales due to beach aspect in relation to offshore islands gale wave height decreased as wave direction rotated eastwards r 0 83 and westwards r 0 88 similarly wave heights were in attuned to variations in positive r 0 68 and negative r 0 72 nao index showing a wave height reduction occurred during weakly negative positive or transitory phases morphological change was attuned to atmospheric variation at a 2 year timelag shelter from offshore islands is given to waves from the predominant southwesterly direction and was confirmed by negligible correlation with south sands morphology however outside the shelter of these offshore islands correlation was found between south eastward rotating wave directions 135 180 and morphological change which resulted in southern and central beach erosion and accretion to the north with a southwesterly rotation 243 256 the opposite was true beach rotation expressed by volume change within the sub aerial zone had a negative phased relationship between beach extremities r 0 94 and a timelagged association within the intertidal zone r 0 55 analyses resulted in the development of two medium timescale rotation models based on incident wave direction and climatic variability results have global implications for headland bays in the lee of offshore islands as well as macro tidal beach areas and consequently similar models could inform local regional and national beach management strategies

ocean waves and teleconnection patterns in the northern hemisphere abstractunderstanding long term ocean wave climate variability is important to assess climate change impacts on coastal and ocean physics and engineering teleconnection patterns can represent wave climate variability in the context of climate change the objective of this study is to identify how large scale spatial distributions of wave heights vary on a monthly basis and how they are influenced by various teleconnection patterns using reanalysis datasets the wave height climate responses to teleconnection patterns in the eastern part of the north pacific and north atlantic are more sensible than in the corresponding western parts the dominant spatial patterns of monthly averaged wave height variability in winter were obtained by empirical orthogonal function analysis the three dominant patterns in the north pacific and north atlantic are similar it is remarkable that one of the three dominant patterns a band shaped pattern exhibits a strong relation to the teleconnection pattern in each ocean t

relationship between foredune profile morphology and aeolian and marine dynamics a conceptual model abstract foredunes are highly dynamic coastal features that are intrinsically connected with their adjacent beaches correlations among parameters representative of aeolian and marine dynamics and the size and location of foredunes were carried out the results indicate that foredune steady state location depends mainly on marine dynamics given that foredune toe level was positively correlated with the total water level of 10 year return period which guarantees that the foredune is only eroded by waves occasionally and therefore will have time to recover and return to its long term morphological state foredune steady state size was characterized by its volume which was positively correlated with aeolian sediment drift potential and exponentially related to the total water level with a 10 year return period aeolian sediment drift potential is indicative of the total amount of sand that potentially reaches the foredune and therefore the foredune size is directly related to it higher total water level with a 10 year return period leads to a foredune located further from the shoreline and at a higher altitude higher toe level as mentioned above consequently the beach is wider and the presence of moisture is expected to be lower this wider and dryer beach allows the aeolian sediment transport to approximate to its maximum value increasing its potential to build a bigger foredune data confirmed that the total water level with a 10 year return period and the foredune volume are exponentially related the correlations found show that foredune steady state size is related to both aeolian sediment drift potential and marine dynamics based on these results a long term conceptual model is proposed to explain the different morphological characteristics of the steady state shape of foredunes as a function of the joint action of marine and wind dynamics

an assessment of geosat wave height and wind speed measurements an assessment is made of the significant wave height and wind speed measurements obtained by the geosat radar altimeter in comparison with buoy data it is found that geosat underestimated the significant wave height by 13 throughout the range of measurements an attempt to compare the wave measurements made by seasat and geosat reveals problems with both data sets for the geosat wind speed measurements it is found that the smoothed brown algorithm usually employed to convert backscattered power to wind speed does not give good results in comparison with buoy measurements a simple linear relationship between backscattered power and wind speed is derived which is in close agreement with the algorithm recently proposed by witter and chelton for wind speeds above 3 m s 1 the implications of these results for deriving wind and wave climatologies from altimeter data are discussed

response of wave dominated and mixed energy barriers to storms wave dominated and mixed energy barriers are extremely dynamic landforms responding to processes operating over a spectrum of time scales ranging from daily to monthly fluctuations related to storm and post storm conditions to century to millennium scale evolution driven by relative sea level change two types of storms are of particular relevance warm core tropical and cold core extratropical cyclones both are responsible for generating very large waves highly energetic surf zone dynamics and sediment transport elevated inshore water levels and extensive morphological responses all cyclones are affected by climate change which governs their frequency intensity and tracks barrier storm response is primarily governed by maximum storm runup and barrier morphology as conceptualised in abby sallenger s storm impact scale model sallenger 2000 this model defines four storm impact regimes and includes erosive as well as accretionary responses on the erosion side the swash regime drives bar and berm flattening the collision regime is marked by dune scarping and beach lowe the overwash regime leads to dune scouring and channel incision and the inundation regime may result in barrier destruction on the deposition side storm berms and beach ridges may form and accrete in the swash and collision regimes localised vertical beach and barrier accretion are associated with the collision and overwash regimes and washover deposition takes place in the overwash and inundation regimes site specific factors play a key role in moderating the morphological response and include storm characteristics type duration and track longshore sediment supply upwelling downwelling currents coastal setting and inner shelf topography the response of a barrier to a tropical or extratropical cyclone can however not be considered in isolation and has to be appreciated in a longer temporal context involving morphological preconditioning due to antecedent wave and water level conditions additionally a simple process response approach of the cause and effect type is inappropriate and a more complex conceptual framework involving thresholds feedbacks resilience and vulnerability will need to be adopted a useful way to visualise and conceptualise more complex storm behaviours and the longer term vulnerability of barriers is the resilience trajectory which maps out the changes in barrier geometry elevation and width over various time scales from weeks to years or even longer and under varying forcing conditions including changes in storminess and sea level rise an increased understanding of barrier response to storms and sequences of storms is required to better quantify long term barrier response to climate change high resolution and comprehensive decadal records of barrier response to storms are a prerequisite to achieve this ambition linking site specific coastal settings hydrodynamic drivers and morphological responses and allowing the recognition of recovery and impact dominated phases the enhanced insights in barrier response to extreme events must then be incorporated into improved coastal response models to help predict the impacts of future climate change on wave dominated and mixed energy barriers around the world 2013 elsevier b v

submarine sedimentation processes in the southeastern terceira rift sao miguel region azores abstract most case studies dealing with the evolution of volcanic islands concentrate on the onshore domain in contrast the interplay of constructional and destructive processes in the offshore domain is often paid less attention although they commonly represent most part of the edifice combining bathymetric and multi channel seismic data this study focuses on the impact of volcanism erosion tectonics time variant sediment supply and climatic oceanographic conditions on the submarine sedimentation processes in the southeastern terceira rift azores plateau where the major onshore volcanic systems at sao miguel island the largest volcanic edifice in the southeastern terceira rift evolved between the last and the previous glacio eustatic sea level minimum an average depth value of 142 m of the corresponding shelf segments indicates a formation during the last glacial maximum and a long term subsidence of approximately 0 6 mm a below the shelf edge the western flank is characterized by submarine volcanism while the northern slope is mostly affected by strong turbidity events favored by the north coast s exposure to north atlantic storm swell these turbidity currents pass the shelf break by retrogressive canyons gullies and follow a widespread system of channels towards the deep sea where gullies are not connected to channel systems or where turbidity currents overspill the channel walls stacked lobe deposits are formed at the southern slope a more constant downslope sediment transport leads to the formation of cyclic steps chutes and pools and further distal turbidity lobes turbidity currents follow morphological features and enter the basins via structural bottlenecks in the basins bottom currents are controlled deviated by volcanic highs or fault scarps where they cause the deposition of drift bodies high local accumulations of sediments caused by a channelized sediment flux bottom currents or onshore volcanism were partly remobilized resulting in slumping sliding and a volcanic ridge partly collapsed due to tectonic stress and or gravity spreading

historical seismicity of the mont dore volcanic province auvergne france unraveled by a regional lacustrine investigation new insights about lake sensitivity to earthquakes lake sediments are relevant natural seismographs over long time scale however because tectonic events are not systematically recorded in lake sediments one forthcoming challenge for paleoseismology is to better assess lake sensitivity to earthquakes to this end a limnogeological investigation including hydroacoustic mapping techniques core sampling and multi proxy sediment analyses has been conducted within four small volcanic lakes located in the mont dore province auvergne france an area with a moderate seismo tectonic activity results show the existence of several gravity reworking processes in the lakes over the last millennium around ad 1300 the occurrence of synchronous events in lakes pavin chauvet montcineyre and guery 100 km 2 area highlights an undocumented earthquake as a common trigger for slope failures in disconnected basins at regional scale the record of this tectonic event may have been favored by human induced increase in sediment load chauvet and montcineyre and or after an abrupt lake level drop pavin affecting the sediment stability in addition synchronous turbidites and mass wasting deposits mwd recorded in lakes pavin and guery provide evidence for a seismic activity during the xix th century potential triggers are historical earthquakes that occurred either in the mont dore area or in the southern part of the limagne fault at this time despite moderate seismic activity in this intraplate volcanic domain these results highlight the role of tectonics as a major trigger in the sedimentary processes dominating these lacustrine infills within the diversity of studied sites it appears that lake sensitivity to earthquakes was not constant over time this sensitivity can be expressed as a combination of external factors namely earthquake magnitude and lake epicenter distance and internal factors such as lake morphology nature of sediment lake level fluctuations and human induced changes in catchment sedimentary load

long term variability of supratidal coastal boulder activation in brittany france abstract high energy supratidal coastal boulder deposit scbd dynamics were investigated on vierge island and pors carn point north and south of western brittany france respectively morphological changes induced by boulder transport and quarrying were quantified using high resolution topographic survey data taken between 2012 and 2017 additional in situ wave parameters and water levels were also recorded over this period 2014 2017 in order to compute the maximum water levels and assess the relationship between scbd morphological changes and specific hydrodynamic conditions during extreme water levels for maximum water levels exceeding a one in ten year event scbds were broadly reworked up to 40 of the total volume during lower intensity events for which maximum water levels were still very high morphological changes represented 1 to 5 of the total volume these morphological and hydrodynamic observations were then used to calibrate a chronology of scbd activation events based on 70 years of hindcast winter maximum water levels these long term time series showed great interannual variability in scbd activation but no significant long term trend winter frequency scbd activation was better correlated to the wepa index r 0 46 than the nao index r 0 1 therefore the wepa index can be considered to be a more significant climate proxy for assessing storm related geomorphic changes in the temperate latitudes of the n e atlantic basin 36 52 n including the brittany coast the potential of scbds as a morphological storm proxy for macrotidal high energy rocky coasts is addressed

a comprehensive pollen and tephra based chronostratigraphic model for the late glacial and holocene period in the french massif central this paper discusses about 250 conventional c 14 ages obtained on peat and gyttja samples that apply to pollen features or tephra beds in the massif central region of france a method to estimate the migration periods of eight late glacial to holocene pollen features typical of the massif central is described a review of all c 14 ages pertaining to tephras of this region enabled the most appropriate age or age range of the tephras to be estimated the chronostratigraphic relationships between pollen features and tephras are discussed and a new comprehensive stratigraphic model is presented the model shows that pollen features are diachronous and should not be used therefore as proxy stratigraphic markers copyright c 1996 inqua elsevier science ltd

towards a european tephrochronological framework for termination 1 and the early holocene the record of deposition of tephras in europe and the north atlantic during the period 18 5 8 0 14 c ka bp the last termination and early holocene is reviewed altogether 34 tephras originating from four main volcanic provinces iceland the eifel district the massif central and italy have been identi ed so far in geological sequences spanning this time interval most of the records have been based until very recently on observations of visible layers of tephras here we report on the potential for extending the areas over which some of the tephras can be traced by the search for layers of micro tephra which are not visible to the naked eye and on the use of geochemical methods to correlate them with known tephra horizons this approach has greatly extended the area in northern europe over which the vedde ash can be traced the same potential exists in southern europe which is demonstrated for the rst time by the discovery of a distinct layer of micro tephra of the neapolitan yellow tu in a site in the northern apennines in italy far to the north of the occurrences of visible records of this tephra the paper closes by considering the potential for developing a robust european tephrostratigraphy to underpin the chronology of records of the last termination and early holocene thereby promoting a better understanding of the nature timing and environmental e ects of the abrupt climatic changes that characterized this period

twentieth century sea ice variability in the weddell sea and its effect on moisture transport evidence from a coastal east antarctic ice core record high resolution study of deuterium excess d excess sea salt sodium ss na and methane sulfonic acid msa in an ice core from coastal dronning maud land cdml east antarctica revealed the

the tectonic fabric of the barbados ridge accretionary complex abstract a map showing near surface structure and other surficial geological features on the barbados ridge accretionary complex has been constructed from gloria long range side scan sonographs detailed bathymetric surveys using seabeam and single and multichannel seismic reflection sections the map shows major variations in the size orientation and style of structures across the accretionary complex that are principally related to the increasing thickness of the complex and the sediment drape upon it and variations along the complex that derive from the northward thinning of sediment accreted from the ocean floor and the effects of ridges in the oceanic basement the development of crossfaulting is mainly associated with basement ridges mud diapirism is abundant in the southern part of the complex and is characteristic of that part of the complex into which turbidites from the orinoco submarine fan are accreted slumping on a variety of scales is another feature of the complex the map is presented at a scale of 1 1063415 4 inches per degree of longitude and also shows bathymetry at 200 m contour intervals

holocene evolution of the western orinoco delta venezuela the pristine nature of the orinoco delta of eastern venezuela provides unique opportunities to study the geologic processes and environments of a major tropical delta remote sensing images shallow cores and radiocarbon dating of organic remains form the basis for describing deltaic environments and interpreting the holocene history of the delta the orinoco delta can be subdivided into two major sectors the southeast sector is dominated by the rio grande the principal distributary and complex networks of anastomosing fluvial and tidal channels the abundance of siliciclastic deposits suggests that fluvial processes such as overbank flooding strongly influence this part of the delta in contrast the northwest sector is represented by few major distributaries and overbank sedimentation is less widespread relative to the southeast sector peat is abundant and occurs in herbaceous and forested swamps that are individually up to 200 km 2 in area northwest directed littoral currents transport large volumes of suspended sediment and produce prominent mudcapes along the northwest coast mapping of surface sediments vegetation and major landforms identified four principal geomorphic systems within the western delta plain 1 distributary channels 2 interdistributary flood basins 3 fluvial marine transitional environments and 4 marine influenced coastal environments coring and radiocarbon dating of deltaic deposits show that the northern delta shoreline has prograded 20 30 km during the late holocene sea level highstand progradation has been accomplished by a combination of distributary avulsion and mudcape progradation this style of deltaic progradation differs markedly from other deltas such as the mississippi where distributary avulsion leads to coastal land loss rather than shoreline progradation the key difference is that the orinoco delta coastal zone receives prodigious amounts of sediment from northwest moving littoral currents that transport sediment from as far away as the amazon system 1600 km late holocene progradation of the delta has decreased delta plain gradients increased water levels and minimized overbank flooding and siliciclastic sedimentation in the northwest sector these conditions coupled with large amounts of direct precipitation have led to widespread peat accumulation in interdistributary basins because peat forming environments cover up to 5000 km 2 of the delta plain the orinoco may be an excellent analogue for interpreting ancient deltaic peat deposits

patterns of low frequency monthly sea level pressure variability 1899 1986 and associated wave cyclone frequencies abstract spatial patterns of low frequency sea level pressure slp variability are identified by performing rotated principal component analysis rpca on a long term 1899 1986 northern hemisphere gridded dataset the analysis is limited to the region 160 e eastward to 40 e due to missing data early in the century the objective is to identify a comprehensive set of highly recurrent slp teleconnection patterns to examine some aspects of their seasonality and to identify the associated mean winter pressure fields and cyclone frequencies occurring at times of opposite eigenvector polarity the results are further described in the context of the southern oscillation and known midtropospheric teleconnection patterns four low frequency variability patterns are identified over the atlantic european sector including i the north atlantic 0scillation nao and spatial patterns with slp variability centers over ii the eastern atlantic eatl iii southern europe and the northern mediterranean basin s

decadal changes in north atlantic atmospheric circulation patterns recorded by sand spits since 1800 ce abstract present day coastal barriers represent around 15 of the world s oceanic shorelines and play an important role as early warning indicators of environmental change among them wave dominated barriers are dynamic landforms that tend to migrate landward in response to storms and sea level change high rates of sediment supply can locally offset the global retrogradation trend providing valuable records of past environmental change occurring on transgressive coasts however geochronological control limits the temporal resolution of such records to millennial or centennial timescales and the decadal or even faster response of wave built barriers to historical climate changes is therefore poorly understood in this study we show that shoreline dynamics of sand spits reconstructed from old cartographic documents has been synchronous on both margins of the north atlantic ocean since about 1800 ce spit growth accelerated drastically during three periods lasting about 15 years characterised by positive north atlantic oscillation nao and negative east atlantic west russia ea wr atmospheric circulation patterns these changes are in phase with periods of increased volcanic activity we use a high resolution wave hindcast 1948 2014 ce in a reference area to confirm the association between nao and ea wr as a proxy for offshore and nearshore wave height and for associated longshore sediment transport lst involved in spit growth a 24 month lagged correlation between sediment transport and volcanic aerosol optical thickness concentration of ashes in the atmosphere is observed suggesting that spit shoreline dynamics at the decadal timescale is partially forced by external climate drivers via cascading effects on atmospheric circulation patterns and wave climate our results imply that nao variability alone is not sufficient to understand the evolution of wave built coastal environments the associated sediment record can be used to reconstruct multi decadal variability of other climate patterns

mud volcanoes of the orinoco delta eastern venezuela abstract mud volcanoes along the northwest margin of the orinoco delta are part of a regional belt of soft sediment deformation and diapirism that formed in response to rapid foredeep sedimentation and subsequent tectonic compression along the caribbean south american plate boundary field studies of five mud volcanoes show that such structures consist of a central mound covered by active and inactive vents inactive vents and mud flows are densely vegetated whereas active vents are sparsely vegetated four out of the five mud volcanoes studied are currently active orinoco mud flows consist of mud and clayey silt matrix surrounding lithic clasts of varying composition preliminary analysis suggests that the mud volcano sediment is derived from underlying miocene and pliocene strata hydrocarbon seeps are associated with several of the active mud volcanoes orinoco mud volcanoes overlie the crest of a mud diapir cored anticline located along the axis of the eastern venezuelan basin faulting along the flank of the pedernales mud volcano suggests that fluidized sediment and hydrocarbons migrate to the surface along faults produced by tensional stresses along the crest of the anticline orinoco mud volcanoes highlight the proximity of this major delta to an active plate margin and the importance of tectonic influences on its development evaluation of the orinoco delta mud volcanoes and those elsewhere indicates that these features are important indicators of compressional tectonism along deformation fronts of plate margins

multibeam bathymetric survey and high resolution seismic investigations on the barbados ridge complex eastern caribbean a key to the knowledge and interpretation of an accretionary wedge abstract an important problem of active margin processes is the way accretionary wedges form in response to oceanic crust subduction new data have been obtained along the barbados ridge in front of the lesser antilles tertiary island arc they include high resolution multichannel seismic data and accurate sea beam bathymetric maps both have been used to propose a 3 dimensional interpretation of tectonic and sedimentary processes related to subduction such as oceanic off scraping ductile folding relative uplift and subsidence fore arc basin evolution and mud diapirism they all improved our knowledge of the evolution of accretionary prisms and more specifically of the barbados ridge development in plio quaternary time previous tectonic events are deduced from recently published geological data from barbados and the lesser antilles islands

morphometric characterization of foredunes along the coast of northern spain abstract foredunes are defined as the first shore parallel dune ridges adjacent to stable and prograding beaches formed on the backshore by aeolian sand deposition influenced by vegetation foredunes have the important functions for mitigating impacts caused by extreme events providing sediment to the beaches during storm and accumulating sediment again under fair weather wave conditions mainly for this reason there is currently great interest in preserving building or recovering foredunes on a long term timescale decades foredunes are recognized as exhibiting possible equilibrium conditions the identification of this condition is of interest to projects involving the recovery and creation of foredune beach systems therefore the main objective of this work is to identify the morphometric characteristics of equilibrium foredunes and the interrelations between the morphometric parameters of height width volume and maximum slope allometric relationships to reach this objective 193 foredune subaerial beach profiles from along the northern coast of spain that have characteristics close to equilibrium conditions were evaluated the results indicate that foredune size can vary significantly however strong correlations between morphometric parameters have been verified and allometric relationships between foredune volume height width and maximum slope are proposed

melange production and the importance of shale diapirism in accretionary terrains although melanges are widely believed to form in subduction zones there is little agreement as to the mechanism by which the characteristic chaotic aspect of a melange develops1 2 debate centres on the relative effects of gravity sliding down the inner trench slope and shearing along thrust faults during offscraping or underplating2 3 the results of deep sea drilling and mapping of modern accretionary terrains4 combined with geophysical investigation of outer arc regions favour the thrust or fold packet model1 4 8 of accretion although some melange deposits exposed on land appear to fit an olistostrome model better1 9 shale diapirs and mud volcanoes are abundant in many modern accretionary terrains10 12 and probably form as a result of rapid overloading caused by tectonic thickening4 13 an investigation of extensive melange zones in northern irian jaya has now shown that they are the product of shale diapirism which suggests that shale diapirism is an important process in the tectonic mixing of accretionary terrains

active mud volcanism observed with landsat 7 etm abstract mud volcanoes are relatively small spatter cones that erupt water laden mud and gases and occur throughout the world for many mud volcanoes the eruption of warm mud 10 40 c can be detected with high resolution thermal satellite imagery we demonstrate the utility of landsat 7 enhanced thematic mapper plus etm imagery for thermal monitoring of active mud volcanism we constrain the temperature and area of active mud discharge and estimate surface heat flux for two isolated mud volcanoes in the copper river basin alaska using band 6 10 4 12 5 m the heat flux results span a wide range due to uncertainties in the environmental conditions at the time of image acquisition but can be constrained to be less than 0 24 mw for each of the two mud volcanoes considering previously published field measurements with this higher resolution band 6 on the etm sensor as well as the high resolution thermal bands on the aster sensor reliable monitoring of mud volcanism on this scale is possible for the first time

variability and predictability of the north atlantic wave climate wave climate across the ocean basins can be described using satellite altimetry here we concentrate on the north atlantic region waves in the north atlantic are strongly seasonal and peak in the winter season the northeastern sector of the atlantic and adjoining shelf seas also exhibit exceptionally high interannual variability in the winter with monthly average significant wave height varying by up to a factor of 2 from one year to the next the strength and geographical distribution of variability is broadly consistent throughout the winter months december march a large fraction of these wave height anomalies is associated with a single pattern of pressure anomalies that resembles the north atlantic oscillation nao a predictor based on nao dependence is trained from relatively recent satellite data and then tested against earlier satellite and in situ data the predictor is successful in large areas of the north atlantic confirming a robust relationship between wave height anomalies and the nao over the last few decades a substantial rise up to 0 6 m in monthly mean wave heights on the northeastern atlantic during the latter part of the twentieth century is attributable to changes in the nao substantial residual anomalies in wave heights exist after the influence of the nao has been subtracted these are partly explained by a second pair of north atlantic patterns in wave height anomalies and sea level pressure anomalies this east atlantic pattern is particularly influential in midwinter and affects the southern part of the northeastern sector including the region of seven stones light vessel

origin of the mud volcanoes in the south east caspian basin iran abstract the gorgan plain se caspian basin contains several mud volcanoes the gharenyaregh neftlijeh sofikam and inche mud volcanoes are active and erupting mud and gas mud volcanoes occur in an area characterized by seismic activity the sofikam mud volcano consists of five craters that define a ne directed 60 linear arrangement which coincides with a subsurface anticline of the western kopeh dagh fold thrust belt the main craters of the inche and neftlijeh mud volcanoes are submerged the gharenyaregh mud volcano is an active mud volcano whose crater is nearly 500 m in diameter clasts collected from the gharenyaregh mud volcano gmv mainly consist of glauconite sandstone limestone ammonite marl and fossiliferous limestone lumachelle with bioclasts ranging in size from millimeters to centimeters x ray diffraction xrd analyses revealed quartz calcite feldspar chlorite illite glauconite halite and gypsum minerals in the clasts and soft materials of the gmv the clasts are comparable with rock fragments originating from the underlying kopeh dagh related formations and the uppermost caspian basin sediments regression of the south caspian sea shoreline from east to west across modern day golestan province seismic activity and buried folds indicate that the south east caspian basin mud volcanoes are located in a tectonically active area and generated from deeper parts of the gorgan plain some large conical hills with a record of historical human activity located between the kopeh dagh zone and the south caspian sea seem to be inactive mud volcanoes