atmospheric methane flux from bubbling seeps spatially extrapolated quantification from a black sea shelf area bubble transport of methane from shallow seep sites in the black sea west of the crimea peninsula between 70 and 112 m water depth has been studied by extrapolation of results gained through different hydroacoustic methods and direct sampling ship based hydroacoustic echo sounders can locate bubble releasing seep sites very precisely and facilitate their correlation with geological or other features at the seafloor here the backscatter strength of a multibeam system was integrated with single beam data to estimate the amount of seeps m2 for different backscatter intensities resulting in 2709 vents in total direct flux measurements by submersible revealed methane fluxes from individual vents of 0 32 0 85 l min or 14 5 37 8 mmol min at ambient pressure and temperature conditions a conservative estimate of 30 mmol min per site was used to estimate the flux into the water to be 1219 1355 mmol s the flux to the atmosphere was calculated by applying a bubble dissolution model taking release depth temperature gas composition and bubble size spectra into account the flux into the atmosphere 3930 4533 mol d or into the mixed layer 6186 6899 mol d from the 21 8 km2 large study area is three times higher than independently measured fluxes of dissolved methane for the same area using geochemical methods 1030 2495 mol d the amount of methane dissolving in the mixed layer is 2256 2366 mol d this close match shows that the hydroacoustic approach for extrapolating the number of seeps m2 and the applied bubble dissolution model are suitable to extrapolate methane fluxes over larger areas

a multi model analysis of the role of the ocean on the african and indian monsoon during the mid holocene we investigate the role of the ocean feedback on the climate in response to insolation forcing during the mid holocene 6 000 year bp using results from seven coupled ocean atmosphere general circulation models we examine how the dipole in late summer sea surface temperature sst anomalies in the tropical atlantic increases the length of the african monsoon how this dipole structure is created and maintained and how the late summer sst warming in the northwest indian ocean affects the monsoon retreat in this sector similar mechanisms are found in all of the models including a strong wind evaporation feedback and changes in the mixed layer depth that enhance the insolation forcing as well as increased ekman transport in the atlantic that sharpens the atlantic dipole pattern we also consider changes in interannual variability over west africa and the indian ocean the teleconnection between variations in sst and sahelian precipitation favor a larger impact of the atlantic dipole mode in this region in the indian ocean the strengthening of the indian dipole structure in autumn has a damping effect on the indian dipole mode at the interannual time scale

foraminiferal response to an active methane seep environment a case study from the adriatic sea abstractit has been analysed the taxonomic structure and isotopic composition of the cytoplasm and tests of living rose bengal stained protoplasm full and dead empty tests benthic foraminifera 63 m in surface sediments from sites with and without methaneseepage at water depths of about 25 m water in the northern adriatic sea and compared these data to isotope analyses of carbonaterocks at the same locations foraminiferal density is higher in seep samples than in control ones despite the low oxygen and highsulphide contents in sediments the 13 c values in foraminiferal cytoplasm at the seep sites are lower than those in cytoplasm ofthe same species in control samples suggesting that beggiatoa may be a food source for the foraminifera and explaining thehigher foraminiferal density at the seep site in contrast the 13 c values of tests of living and dead benthic foraminifera at seep siteswere not significantly different from those in tests of the same species collected at the control sites therefore the carbon isotopevalues of foraminiferal tests in this area do not reflect the ones of the methane seepage although the authigenic carbonate incalcareous sandstones of the methane seepage area is significantly negative and indicates the contribution of methane seepage thesimilar carbon isotope values measured in the foraminiferal tests from shallow settings of the north eastern adriatic sea seemtherefore to be independent of methane seepages 2006 elsevier b v all rights reserved

active degassing across the maltese islands mediterranean sea and implications for its neotectonics abstract the maltese islands located in the central mediterranean sea are intersected by two normal fault systems associated with continental rifting to the south due to a lack of evidence for offshore displacement and insignificant historical seismicity the systems are thought to be inactive and the rift related deformation is believed to have ceased in this study we integrate aerial marine and onshore geological geophysical and geochemical data from the maltese islands to demonstrate that the majority of faults offshore the archipelago underwent extensional to transtensional deformation during the last 20 ka we also document an active fluid flow system responsible for degassing of ch4 and co2 the gases migrate through carbonate bedrock and overlying sedimentary layers via focused pathways such as faults and pipe structures and possibly via diffuse pathways such as fractures where the gases seep offshore they form pockmarks and rise through the water column into the atmosphere gas migration and seepage implies that the onshore and offshore faults systems are permeable and that they were active recently and simultaneously the latter can be explained by a transtensional system involving two right stepping right lateral nw se trending faults either binding a pull apart basin between the islands of malta and gozo or associated with minor connecting antitethic structures such a configuration may be responsible for the generation or reactivation of faults onshore and offshore the maltese islands and fits into the modern divergent strain stress regime inferred from geodetic data

a field based classification scheme for gravel beaches a tripartite classification of gravel beaches based upon morphodynamic properties is proposed and demonstrated for 42 new zealand beaches the main advantage of this scheme is that it is based on simple visual classification that can be applied globally in the field and is underpinned by morphodynamic differences between the beach types the three types identified from the results are 1 pure gravel beach 2 mixed sand and gravel beach 3 composite gravel beach pure gravel beaches have steep slopes tan 0 08 0 24 and gravels extending from the storm berm to below mean low water spring tide level mixed sand and gravel beaches have moderate slopes tan 0 04 0 13 with sand and gravel entirely mixed both cross shore and at depth composite gravel beaches have a steep gravel berm fronted by a low angle intertidal terrace with overall beach slopes of tan 0 05 0 14 on composite beaches there is distinct hydrodynamic cross shore sorting of the sand and gravel component these broad types are tested using discriminant analysis and the three classes are shown to be highly significant f 16 24 df 8 p 0 00005 the key discriminating variables are iribarren number beach width average grain size and storm berm height

source rock distribution model of the periadriatic region the periadriatic area is a mosaic of geological provinces comprised of spatially and temporally similar tectonic sedimentary cycles tectonic evolution progressed from a triassic early jurassic liassic continental rifting stage on the northern edge of the african craton through an early jurassic middle liassic late cretaceous eocene oceanic rifting stage and passive margin formation to a final continental collision and active margin deformation stage in the late cretaceous eocene to holocene this evolution occurred in a transtensional and transpressional framework resulting from the oblique separation and convergence of the african and european plates extensive shallow water carbonate platform deposits covered large parts of the periadriatic region in the late triassic platform breakup and development of a platform to basin carbonate shelf morphology began in the late triassic and extended through the cretaceous on the basis of this paleogeographic evolution the regional geology of the periadriatic region can be expressed in terms of three main upper triassic paleogene sedimentary sequences the platform sequence sequence a the platform to basin sequence sequence b and the basin sequence sequence c these sequences developed during the initial rifting and subsequent passive margin formation tectonic stages three distinct episodes of source bed deposition can be identified middle upper triassic to lower jurassic liassic organic rich oil prone and mature source beds generally are structurally controlled and are closely associated with transtensional intraplatform basins formed in the early continental rifting stage the principal triassic source basins and most of the surface hydrocarbon indications and economically important oil fields of the periadriatic region are associated with sequence b areas the second episode of organic rich rocks deposition includes both shallow and deeper water facies of jurassic cretaceous age thin immature deep water epioceanic organic rich marls and shales are generally bathymetrically controlled these units are related to basin wide anoxic events in the tethys ocean and its submerged continental margin and are associated with sequence b areas middle upper cretaceous shallow water oil prone facies occur in isolated anoxic basins within carbonate platforms these source sequences are generally thicker and are associated with sequence a areas no major hydrocarbon accumulation can be directly attributed to the jurassic cretaceous epioceanic and intraplatform source rock sequences the third episode of source bed deposition characterizes the final active margin deformation stage and is represented by upper tertiary organic rich terrigenous units mostly gas prone these are essentially associated with turbiditic and flysch sequences of foredeep basins and have generated the greater part of the commercial biogenic gases of the periadriatic region

mud volcanoes discovered offshore sicily abstract numerous active mud volcanoes have been recognized for the first time from seismic reflection and sidescan surveys carried out in 2002 over the hyblean malta plateau 10 miles from the southern coast of sicily southern italy mediterranean sea along faults adjacent to the scicli fracture zone our geophysical data show clearly the presence of several tens of mud volcanoes at water depths between 70 and 170 m they have scales of order 10 m in diameter and several meters in height gas apparently vents from most of the mud volcanoes and is detected acoustically in the sediments around the cones to distances of about 50 m this discovery represents a new important step in the study of mud volcanism distribution and highlights the potential of the sicilian shelf as a hydrocarbon prone area and a natural source of greenhouse gases

reply to comment by a kopf on methane emission from the mud volcanoes of sicily italy and notice on ch4 flux data from european mud volcanoes

oxygen minimum zone variations in the tropical pacific during the holocene we performed simulations with a global model of ocean biogeochemistry forced with orbitally driven anomalies of oceanic conditions for the mid holocene known as holocene climate optimum to investigate natural variability in the eastern equatorial pacific oxygen minimum zone eep omz while the global mean temperature during the mid holocene was likely slightly higher than the 1961 1990 mean the sea surface temperature in the eep was slightly lower mid holocene oxygen concentrations in the eep omz are generally increased locally by up to 50 and the eep omz volume was depending on definition of the omz threshold at least 6 lower these higher oxygen levels are the combined result of competing physical and biogeochemical processes our results imply that mechanisms for past changes in the eep omz intensity and extension can differ from the global warming driven decline in oxygen levels observed for the recent decades and predicted for the future

modeling tsunami hazards from manila trench to taiwan abstract the 2006 dual pingtung earthquake event and the 2004 south asia tsunami highlighted the potential tsunami hazards from manila trench manila trench is only about 100 km away from taiwan therefore one shall punctuate the importance of thorough study on all possible tsunami scenarios for hazard mitigation based on the faults parameters issued by usgs and the seismic record from global cmt this study creates a hypothetical earthquake tsunami scenario caused by seismic motion at manila trench the magnitude of the earthquake is 9 35 mw the total length is 990 km and the maximum initial free surface height is 9 3 m the initial displacement profile is provided in this paper an open source code comcot is adopted to perform the simulation of the tsunami propagation runup and inundation around taiwan nested grid system and moving boundary technique are adopted to study runup and inundation the result shows that the maximum wave height is 11 m in southern taiwan serious flooding is observed in the southwest coast of taiwan tsunami inundation is able to reach 8 5 km inlandward due to the refraction effect 8 m wave height is noted in the northeast coast of taiwan the detailed tsunami behavior around taiwan is described in the context

recognising biodegradation in gas oil accumulations through the δ13c compositions of gas components a large suite of natural gases 93 from the north west shelf and gippsland and otway basins in australia have been characterised chemically and isotopically resulting in the elucidation of two types of gases about 26 of these gases have anomalous stable carbon isotope compositions in the c1 c4 hydrocarbons and co2 components and are interpreted to have a secondary biogenic history the characteristics include unusually large isotopic separations between successive n alkane homologues up to 29 pdb and isotopically heavy co2 up to 19 5 pdb irrespective of geographic location these anomalous gases are from the shallower accumulations 600 1700 m where temperatures are lower than 75 c the secondary biogenic gases are readily distinguishable from thermogenic gases 74 of this sample suite which should assist in the appraisal of hydrocarbons during exploration where hydrocarbon accumulations are under 2000 m while dissolution effects may have contributed to the high 13c enrichment of the co2 component in the secondary biogenic gases the primary signature of this co2 is attributed to biochemical fractionation associated with anaerobic degradation and methanogenesis correlation between biodegraded oils and biodegraded dry gas supports the concept that gas is formed from the bacterial destruction of oil resulting in secondary biogenic gas furthermore the prominence of methanogenic co2 in these types of accumulations along with some isotopically depleted methane provides evidence that the processes of methanogenesis and oil biodegradation are linked it is further proposed that biodegradation of oil proceeds via a complex anaerobic coupling that is integral to and supports methanogenesis

extremely high energy wave deposits inside the great barrier reef australia determining the cause tsunami or tropical cyclone abstract a hydrodynamic approach is used to determine whether tsunami or cyclone generated waves were responsible for the deposition of fields of well imbricated rock boulders up to 290 tonnes along the coast of cairns inside the great barrier reef australia calculations of the overturning moments show that only tsunami are capable of moving such large boulders in this environment it is hypothesised that large tsunami 11 m have been able to penetrate the great barrier reef through wide 5 10 km 50 70 m deep passages between individual reefs three such passages each approximately 35 km apart and oriented in the same direction exist in the cairns region it is possible that these passages have funnelled and amplified palaeotsunamis the preferential location of eroded coral boulders up to 3 m in length on reef flats alongside these passages and their absence on other reefs throughout the region provide further evidence that extremely high energy waves have been able to penetrate the great barrier reef into the inner channel adjacent to the mainland carbon 14 ages of the coral boulders on these reef flats matches closely the ages of coral fragments pinned below the very large rock boulders along the coast these ages suggest that the cairns region has experienced large tsunami twice over the last millennium

geochemistry and habitat of natural gases in italy abstract systematic chemical and isotopic analyses were carried out on natural gases from 92 fields which represent more than 90 of the original gas reserves of italy a quantitative assessment of the various genetic gas types indicates that most of the gaseous hydrocarbons 80 were generated through bacterial activity and or diagenetic processes while only a minor amount 20 was produced by thermal degradation of organic matter the formation of the gas accumulations was geologically controlled by the neogene tectonic phases and by the sedimentary events associated with the growth of the apennines and southern alps in fact about 80 of italian natural gas reserves have been found in the apennine foredeep while the remaining part is equally distributed in the folded belt and in the foreland furthermore the influence exerted by tectono sedimentary characteristics is emphasized by the fact that thermal degradation of organic matter was the only process responsible for most of the gas generated in the apennine folded belt 97 thermogenic gases on the other hand the high rates of subsidence turbiditic sedimentation and very early compressional tectonics in the foredeep favored processes leading to the accumulation of very large quantities of biogenic gas 82 moreover geochemical and geological data as well as mathematical modelling demonstrate that migration and accumulation of italian natural gases mainly occurred later than 5 my ago and in some cases these phenomena are still active in fact in the multipay zone gas fields of the northern adriatic a kind of steady equilibrium is reached between loss of gas through the thin cap rocks often less than 1 m and continous replenishment from the bacterial fermentation and or low temperature thermochemical reactions

climate and co2 effects on the vegetation of southern tropical africa over the last 37 000 years the savanna vegetation of southern tropical africa is characterized by co dominance of c 4 grasslands and c 3 woodlands long term variations in the tropical savanna vegetation in arid and semi arid climates are commonly considered to be primarily sensitive to precipitation and atmospheric co2 concentrations the sensitivity of tropical vegetation to temperature however is often considered as secondary or negligible particularly in paleostudies due to difficulties of reconstructing terrestrial temperature in the tropics in this study we use the terrestrial vegetation model biome4 which was forced by climate simulations from the kiel climate model kcm for the holocene and by climate reconstructions for the most recent glacial period to understand reconstructed vegetation changes in southern tropical africa of the past 37 000 yr we focus on these two periods because vegetation reconstructions from a marine sediment core near the zambezi river mouth cannot be explained by precipitation changes and changes of atmospheric co2 alone for the holocene we force biome4 simulations with reconstructed atmospheric co2 concentrations and spatial and seasonal climate patterns from the early and mid holocene 9 5 and 6 ka bp simulations with the kcm for the glacial period we analyze idealized experiments based upon reconstructed temperature precipitation and co2 at 31 28 and 21 ka bp our study shows that both holocene and glacial simulations of vegetation cover exhibit good agreement with reconstructed c 4 c 3 ratios when temperature changes are taken into account while both precipitation and temperature control the c 4 c 3 ratio during the holocene atmospheric co2 and temperature variations are major factors controlling vegetation changes during the glacial period in our simulations variations in temperature along with precipitation and atmospheric co2 reconcile the evolution of vegetation observed in the zambezi catchment during the last 37 000 yr in consequence the effect of temperature variations on tropical savanna vegetation should be taken into account with respect to modeling past or future climates c 2014 elsevier b v all rights reserved

methane seeps and mud volcanoes in italy gas origin fractionation and emission to the atmosphere molecular composition ch 4 isotopes and gas flux of all main terrestrial mud volcanoes and other methane seeps in italy are being assessed for the first time whereas 74 of the italian gas reservoirs are biogenic about 80 of the seeps release thermogenic gas dry seep gas generally maintains the reservoir c 1 c 2 c 3 bernard ratio while mud volcanoes show molecular fractionation likely occurring during advective migration accordingly a simple and direct use of the bernard parameter might be misleading when applied to mud volcanoes as it could not always reflect the reservoir composition methane flux into the atmosphere from macro seep areas is in the order of 10 2 10 6 t km 2 y 1 microseepage is widespread throughout large areas and on a regional scale it provides the main methane output a first emission estimate for the total hydrocarbon prone area of italy suggests levels of 105 t y 1 comparable to national sources from fossil fuel industry

foraminifera as indicators of methane rich environments a study of modern methane seeps in santa barbara channel california methane hydrates have been implicated as a possible forcing mechanism for rapid climate change during the late quaternary via the release of methane from marine reservoirs carbon isotopic excursions of foraminifera observed in high resolution sediment records from santa barbara basin odp site 893 have been interpreted as evidence of episodes of methane release during the late quaternary however the potential relationship between methane in the modern environment and its effect on the stable isotopic composition of benthic and planktonic foraminifera is not well understood short cores taken inside a 500 m diameter pockmark with active methane seeps in santa barbara channel ca usa yield information on the effect of high concentrations of environmental methane on foraminiferal assemblages and their stable isotopic composition these seeps reside at 120 m water depth in the eastern portion of the channel associated with faults and fractures in the miocene monterey formation planktonic foraminiferal assemblages and radiocarbon ages show that surface sediments are of late glacial age 25 300 calendar years this finding suggests an absence of holocene and deglacial sedimentation in the seep area likely due the formation of the pockmarks and subsequent winnowing or lack of sedimentation benthic foraminiferal assemblages are marked by high abundance of bolivina tumida a species previously observed during interstadial episodes and the early holocene in santa barbara basin interpreted to include episodes of high methane flux from the basin while oxygen isotopic values of both benthic and planktonic foraminifera appear normal for cool glacial conditions negative carbon isotopic values are seen in benthic foraminifera primarily in the near surface intervals in one interval 1 2 cm below surface both benthic and planktonic species record highly negative carbon isotopic values implying that isotopically light methane influenced the entire water column this spike is of similar or larger magnitude than several earlier observed spikes in the late quaternary record from odp site 893 single specimen isotopic analyses give an indication of the total range of carbon isotopic values recorded 0 01 to 25 23 for benthics 0 07 to 22 22 for planktonics in the spike interval since modern methane seeps are commonly associated with authigenic carbonate precipitation scanning electron microscopy was used to assess the possibility that post depositional alteration may have affected the isotopic composition of the test these experiments indicate that authigenic carbonate is absent and therefore unable to account for the highly negative carbon isotopic signatures these data improve our understanding of methane associated environments by showing that foraminiferal isotopic composition and assemblages may be used to discern the flux of methane from the oceanic reservoir in the geologic record

stable imbrication and delicate unstable settings in coastal boulder deposits indicators for tsunami dislocation abstract medium sized and coarse debris pebbles and boulders can exhibit patterns of setting particularly if they are elongated or tabular these patterns such as imbrication indicate certain transport processes mostly as to direction and character many years of observation and measuring of coarse coastal deposits are the basis for the conclusions presented here on environmental transport processes their character and their energy beside imbrication special emphasis is given to unstable or delicate settings of large boulders that evidently have remained in these positions from hundreds to thousands of years this deserves an explanation to how they arrived at these positions and why they have not changed into a more stable position given an environment of constant energy input along coastlines the discussion lays emphasis on whether both settings of mega boulders can be indicative of tsunami transport processes

the influence of microhabitats on the carbon isotopic composition of deep sea benthic foraminifera we report 13c and 18o values for rose bengal stained benthic foraminifera from a set of box cores from continental margin environments in the atlantic and pacific oceans these isotopic results are compared with foraminiferal distribution data and pore water 13c profiles to evaluate the importance of environmental microhabitat effects on the carbon isotopic composition of benthic foraminifera the 13c values of infaunal taxa are consistently lower than those of epifaunal taxa suggesting that microhabitat effects on test composition do exist the 13c differences between foraminiferal carbonate and bottom water dissolved inorganic carbon are not correlated with the 18o differences between benthic foraminifera tests and equilibrium calcite but they do correlate with variations in the chemistry of sediment pore waters however interspecific 18o differences as well as 13c differences between species with similar vertical distributions in the sediments indicate that taxon specific vital effects also influence test composition

structural setting of the adriatic basin and the main related petroleum exploration plays abstract most of the oil and gas resources located within the adriatic domain are genetically linked to the flexure of the adria continental margin and to the evolution of the apennines fold and thrust belt the source rocks contained in the pre flexure epi continental successions reached the maturity window during the flexural subsidence or alternatively the flexural accommodating siliciclastic flysch themselves generated and stored hydrocarbons the petroleum exploration plays of the adriatic domain are tentatively classified in this paper according to their geological evolution with respect to the apennines fold and thrust belt the description of the geological evolution of these structures and related petroleum plays are described including plays set in undeformed or poorly deformed foreland areas a new isochrones map showing the structural setting of the substratum at the level of the fucoidi fm is presented several different groups of structures can be recognized in the adriatic domain that can be connected to the final phases of deformation of the apennines or to the interaction with the dinarides fold and thrust belt front to the east

a note on orbital control of equator pole heat fluxes we note that orbital milankovitch variations in particular the precession of the equinoxes can lead to profound variations in the flux of heat from the tropics to higher latitudes the mechanism involves changing the intensity of the hadley circulation by varying the maximum displacement from the equator of the zonally averaged surface temperature maximum in summer the precession of the equinoxes causes this quantity to vary by more than a factor of 2 the intensity of the hadley circulation has a major influence on the heat fluxes in the winter hemisphere summer heat fluxes are generally small although the precession cycle is characterized by periods in the neighborhood of 20000 years the variations are modulated by the eccentricity whose variation is dominated by periods in the neighborhood of 100000 years and 400000 years we show how the fact that both small and large heat fluxes lead to low snowfall and hence small glacial accumulation causes the demodulation of the heat flux leading to dominant eccentricity periods in the resulting glaciation

isotopic evidence for the incorporation of methane derived carbon into foraminifera from modern methane seeps hydrate ridge northeast pacific the presence of modern methane seeps at hydrate ridge offshore oregon provide an opportunity to study the influence of methane seeps on the ecology and geochemistry of living foraminifera a series of cores were collected from the southern summit of hydrate ridge in 2002 samples were preserved and stained to determine the 13c composition of three species of live stained and dead benthic foraminifera uvigerina peregrina cibicidoides mckannai and globobulimina auriculata specimens were examined under light and scanning electron microscopy sem and exhibit no evidence of diagenesis or authigenic carbonate precipitation individual living foraminifera from seep sites recorded 13c values from 0 4 to 21 2 indicating the isotopic influence of high methane concentrations average 13c values calculated from single specimens range from 1 28 to 5 64 at seep sites and 0 81 to 0 85 at a control off seep site two distinct seep environments distinguished by the presence of microbial mats or clam fields were studied to determine environmental influences on 13c values individual foraminifera from microbial mat sites exhibited more depleted 13c values than those from clam field sites we interpret these differences as an effect of food source and or symbiotic microbes on foraminiferal carbon isotopic values acting to magnify the negative 13c values recorded via the dic pool no statistical difference was found between 13c values of live vs dead specimens this suggests that authigenic carbonate precipitation did not play a dominant role in the observed isotopic compositions however a few dead specimens with extremely negative 13c composition 12 do indicate potential evidence for an authigenic influence on the recorded 13c composition

terrestrial methane seeps and mud volcanoes a global perspective of gas origin abstract a global database of gas composition and methane stable isotopes of 143 terrestrial mud volcanoes from 12 countries and 60 seeps independent from mud volcanism from eight countries was compiled and examined in order to provide the first worldwide statistics on the origin of methane seeping at the earth s surface sixteen seep data were coupled with their associated subsurface reservoirs the surface seepage data indicate that at least 76 of the mud volcanoes release thermogenic gas with only 4 biogenic and 20 with mixed character the average 201 data of methane concentration and methane carbon isotope ratios 13 c 1 of mud volcanoes are 90 v v and 46 4 respectively the other types of seeps which are independent from mud volcanism have an average 13 c 1 value that is slightly higher 42 9 gases from mud volcanoes are generally lighter more methane less ethane and propane than their associated reservoir gases suggesting a molecular fractionation during advective fluid migration other types of seeps especially dry seeps maintain the reservoir c 1 c 2 c 3 bernard ratio mud volcanoes behave like a natural refinery and the origin of gas more isotopically enriched than 50 and with c 1 c 2 c 3 500 should be attributed to a thermogenic source rather than partial oxidation of biogenic gas some data that appear biogenic in the bernard diagram can be explained by molecular fractionation of mixed gas consequently the bernard parameter may be misleading when applied to mud volcanoes since it does not always reflect the original gas composition the mechanisms of the molecular advective segregation should be studied quantitatively by specific models and experiments

benthic foraminifera associated with cold methane seeps on the northern california margin ecology and stable isotopic composition release of methane from large marine reservoirs has been linked to climate change as a causal mechanism and a consequence of temperature changes during the quaternary and the paleocene these inferred linkages are based primarily on variations in benthic foraminiferal stable isotope signatures few modern analog data exist however to assess the influence of methane flux on the geochemistry or faunal characteristics of benthic foraminiferal assemblages here we present analyses of the ecology and stable isotopic compositions of living rose bengal stained and dead fossil foraminifera 150 mm from cold methane seeps on the slope off of the eel river northern california 500 525 m and discuss potential applications for reconstructions of methane release in the past and present calcareous foraminiferal assemblages associated with calyptogena clam bed seeps were comprised of species that are also found in organic rich environments cosmopolitan paleoceanographically important taxa were abundant these included uvigerina bolivina chilostomella globobulimina a ndnonionella we speculate that seep foraminifera are attracted to the availability of food at cold seeps and require no adaptations beyond those needed for life in organic rich reducing environments oxygen isotopic values of the tests of living foraminiferal assemblages from seeps had a high range up to 0 69 as did carbon isotopic values up to 1 02 many living foraminiferal isotope values were within the range exhibited by the same or similar species in non seep environments carbon isotopic values of fossil foraminifera found deeper in the sediments 18 20 cm however were 4 10 u peregrina and 3 60 b subargentea more negative than living d 13 c values these results suggest that d 13 c values of foraminiferal tests reflect methane seepage and species specific differences in isotopic composition and can indicate temporal variations in seep activity a better understanding of foraminiferal ecology and stable isotopic composition will enhance paleo seep recognition and improve interpretations of climatic and paleoceanographic change 2000 elsevier science b v all rights reserved

a thermogenic hydrocarbon seep in shallow adriatic sea italy gas origin sediment contamination and benthic foraminifera abstract gaseous and liquid hydrocarbons are seeping from sandy sea bottom 10 m deep about 2 4 km nne of civitanova marche harbour in central adriatic sea italy we investigated the origin of the gas the presence of a wide range of aromatic and aliphatic hydrocarbons and trace metals in shallow sediments as well as the stable carbon and oxygen isotope composition of benthic foraminifera in absence of detailed seismic images and subsurface geochemical data we tried to estimate the source rock type and maturity based only on seep gas geochemistry molecular and isotopic composition of gas bubbles showed that the ch4 rich gas is thermogenic 13 c ch 4 55 2 h ch 4 280 c1 c2 c3 13 c co 2 12 fluid seepage might be due to a local fracture zone corresponding to the intersection of nnw sse thrust faults with a ne sw regional transversal deformation belt compared to other shallow marine seeps in europe the amount of methane released into the atmosphere is negligible 102 103 kg of ch4 per year but the seep also releases ethane and propane 103 104 l per year which are photochemical pollutants and are not emitted by microbial gas seeps compared to a reference site one nautical mile far from the seep the seabed sediments show higher concentrations of various classes of chemicals such as benzene toluene and ethylbenzene semivolatile and non volatile aliphatic hydrocarbons c10 c40 and phenols 2 methylphenol and 2 4 dichlorophenol these compounds likely derive from the oil seepage the sediments at the seepage site and those at the reference site have similar concentrations of trace metals arsenic barium cadmium chromium copper iron manganese nickel lead vanadium zinc mercury typical of uncontaminated and shallow coastal areas finally we provided the first data on foraminifera associated to thermogenic hydrocarbons no endemic foraminifera species or authigenic carbonates occur in the sediments carbon isotopic composition of quinqueloculina padana where oil slick prevails is less variable than in the gas bubbling site however thermogenic methane and oil do not apparently decrease the 13c value of foraminifera carbonate shell

global monsoons in the mid holocene and oceanic feedback the response of the six major summer monsoon systems the north american monsoon the northern africa monsoon the asia monsoon the northern australasian monsoon the south america monsoon and the southern africa monsoon to mid holocene orbital forcing has been investigated using a coupled ocean atmosphere general circulation model foam with the focus on the distinct roles of the direct insolation forcing and oceanic feedback the simulation result is also found to compare well with the ncar csm the direct effects of the change in insolation produce an enhancement of the northern hemisphere monsoons and a reduction of the southern hemisphere monsoons ocean feedbacks produce a further enhancement of the northern africa monsoon and the north american monsoon however ocean feedbacks appear to weaken the asia monsoon although the overall effect direct insolation forcing plus ocean feedback remains a strengthened monsoon the impact of ocean feedbacks on the south american and southern african monsoons is relatively small and therefore these regions especially the south america experienced a reduced monsoon regime compared to present however there is a strong ocean feedback on the northern australian monsoon that negates the direct effects of orbital changes and results in a strengthening of austral summer monsoon precipitation in this region a new synthesis is made for mid holocene paleoenvironmental records and is compared with the model simulations overall model simulations produce changes in regional climates that are generally consistent with paleoenvironmental observations

disentangling seasonal signals in holocene climate trends by satellite model proxy integration past sea surface temperatures ssts are routinely estimated from organic and inorganic remains of fossil phytoplankton or zooplankton organisms recovered from sea floor sediments potential seasonal biases of paleo proxies were intensely studied in the past however even for the two most commonly used paleo proxies for sst uk0 37 and mg ca ratios a clear global picture does not yet exist in the present study we combine holocene sst trends derived from uk0 37 and mg ca ratios with results from idealized climate model simulations forced by changes in the orbital conguration which represents the major climate driver over the last 10 kyrs such changes cause a spatio temporal redistribution of incoming solar radiation resulting in a modulation of amplitude and phasing of the seasonal cycle considering that the climate signal recorded by a plankton based paleo proxy may be aected by the seasonal productivity cycle of the respective organism we use the modern relationship between sst and marine net primary production npp both obtained from satellite observations to calculate a seasonality index si as an independent constraint to link modeled sst trends with proxy data although the climate model systematically underestimates holocene sst trends we find that seasonal productivity peaks of the phytoplankton based uk0 37 result in a preferential registering of the warm cold season in high low latitudes as it was expected from the si distribution the overall smoother trends from the zooplankton derived mg ca ssts suggest a more integrated signal over longer time averages which may also carry a seasonal bias but the spatial pattern is less clear based on our ndings careful multi proxy approaches can actually go beyond the reconstruction of average climate trends specifically allowing to resolve the evolution of seasonality

offshore and onshore seepage of thermogenic gas at katakolo bay western greece abstract considerable seepage of natural gas occurs throughout the katakolo bay both at sea and on land along the ionian coast of peloponnesus western greece explosive levels of ch4 and toxic concentrations of h2s accumulating in the ground pose a severe hazard for humans and tourist infrastructures a wide offshore and onshore gas survey including marine remote sensing underwater exploration by a towed instrumented system compositional and isotopic analyses and flux measurements of gas allowed us to assess that a gas seepage takes place along two main normal faults b offshore side scan sonographs recorded at least 823 gas bubble plumes over an area of 94 200 m2 at depths ranging from 5 5 to 16 m c offshore and onshore seeps release the same type of thermogenic gas 13cch4 34 to 36 d offshore gas showed increased stable carbon isotopic ratio of co2 and propane which suggests enhanced biodegradation of hydrocarbons e isotopic data combined with thermogenic gas generation modeling and maturity plots suggest that the gas is related to a deep petroleum system with jurassic carbonate reservoirs triassic source rocks and triassic evaporites f h2s 34s 2 4 is produced by thermochemical sulfate reduction in deep anhydrites in contact with hydrocarbon rich carbonates g due to the shallow depth more than 90 of ch4 released at the seabed enters the atmosphere consistent with theoretical bubble dissolution models with a mean plume output of 0 12 kg d 1 total offshore ch4 output was estimated in the range of 33 to 120 t y 1 and h in the onshore area at least 50 gas vents in the harbor and a large seep on the adjacent faros hill emit in total about 89 t ch4 y 1 katakolo results to be one of the biggest thermogenic gas seepage zones in europe

field observations of sediment transport across the rocky coast of east taiwan impacts of extreme waves on the coastal morphology by typhoon soudelor abstract after the 2015 typhoon soudelor large boulders and mixed sediments deposited extensively across the beach along the east coast of taiwan field measurements of these storm related sediments provide the first hand evidence to document the impacts of extreme waves induced by typhoon soudelor although the maximum inundation distance is only 170 m due to the lack of beach buffer zone the weight of the largest boulder was estimated over 1 t and the maximum run up was estimated up to 11 9 m the clast distribution of the washover and the beach face sediments exhibited reverse directions of coarsening reflecting different stages of wave propagation our field records show that a super typhoon like soudelor can potentially leave footprints of extreme values in the geologic records therefore a comprehensive understanding on the occurrence of the sediments and the depositional environment should be carefully considered to pin down the origin of the archived extreme events in addition the formation of the higher extreme wave berm and the destruction of the lower swell berm at the yen liao beach displayed the power of the storm surges suggesting the important role of the run up on the evolution of the berm

methane emission from the mud volcanoes of sicily italy 1 mud volcanoes represent the largest expression of natural methane release into the atmosphere however the gas flux has never been investigated in detail methane output from vents and diffuse soil degassing is herewith reported for the first time measurements were carried out at 5 mud volcano fields around sicily italy each mud volcano is characterized by tens of vents and bubbling pools in the quiescent phase methane emission from single vents ranges between 0 01 and 6 8 kg day diffuse soil leakage around the vents is in the order of 102 104 mg m 2 d 1 an exceptional flux of 106 mg m 2 d 1 was recorded close to an everlasting fire soil ch4 flux is positive even at large distances from the mud volcano fields suggesting a diffuse microseepage over wider areas a total of at least 400 tons ch4 per year can be estimated over the area investigated alone 1 5 km2

benthic foraminifera of the blake ridge hydrate mound western north atlantic ocean abstract in a 240 m 70 m area at the top of the blake ridge diapir water depth 2150 m the benthic foraminiferal assemblage in surface sediment 0 1 cm consists of about 130 species hydrocarbon seepage is indicated here by the presence of methanotrophic bivalves and white bacterial mats and by present day formation of gas hydrate the foraminiferal assemblage density is generally high indicating an abundance of food bolivina lowmani and globocassidulina subglobosa dominate the assemblage in the silt clay substrate whether at the edge of bathymodiolid mussel beds or under bacterial mats the only notable difference between these two sample groups is in the higher variation of foraminiferal density in the mussel bed samples a control sample at 32 29 654 n and 76 11 324 w taken from bioturbated sediment light grey silt and clay with no visible bacterial or molluscan colonization is comparable to the seep samples in the distribution of calcareous species but shows a much higher diversity and abundance of agglutinated species no segregation of foraminiferal species by substrate geochemistry can be inferred for the seep samples and the possible effect of variable sulfide or methane fluxes on the community cannot be demonstrated by our data

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

tracing seafloor methane emissions with benthic foraminifera results from the ana submarine landslide eivissa channel western mediterranean sea article the hypothesis that benthic foraminifera are useful proxies of local methane emissions from the seafloor has been verified on sediment core ks16 from the headwall of the ana submarine landslide in the eivissa channel western mediterranean sea the core ms312 from a nearby location with no known methane emis sions is utilised as control the core was analysed for biostratigraphy benthic foraminiferal assemblages hyalinea balthica and uvigerina peregrina carbon and oxygen stable isotope composition and sedimentary structures the upper part of the core records post landslide deglacial and holocene normal marine hemipe lagic sediments with highly abundant benthic foraminifera species that are typical of outer neritic to upper bathyal environment in this interval the 13 c composition of benthic foraminifera indicates normal marine environment analogous to those found in the control core below the sedimentary hiatus caused by the em placement of the slide the foraminiferal assemblages are characterised by lower density and higher shannon index markedly negative 13 c shifts in benthic foraminifera are attributed to the release of methane through the seabed the mean values of the 13 c anomaly in u peregrina are 0 951 0 208 in the pre landslide sediments and 0 269 0 152 in post slide reworked sediments deposited immediately above the hiatus the 13

discrimination of boulders deposited by tsunamis and storm waves at ishigaki island japan abstract the ryukyu islands japan where numerous boulders are deposited on the reef and on land might be ideal research fields of boulders deposited by tsunami and storm waves because many typhoons and several tsunamis attacked the same area during its history this study investigates the size position and the long axis orientation of 626 boulders at ibaruma and shiraho reefs at ishigaki island japan to elucidate the sedimentary differences of boulders deposited by tsunamis and storm waves in one area two distinct groups of boulders were found at these reefs boulders on the reef crest group 1 and along the shoreline group 2 boulders in group 1 porites sp of moat origin the group 2 boulders were remarkably heavier 14 c age based on results of this study we infer that tsunami boulders in these islands so called tsunami ishi can be discriminated from boulders of storm wave origin based on their sedimentary differences this sedimentological approach is expected to be applicable to other boulder fields throughout the world our results further suggest that the spatial and grain size distribution of tsunami boulders are very useful to elucidate local flow characteristics of the tsunami for example the group 2 tsunami boulders were deposited below the high tide line irrespective of size some were split into several pieces they were probably deposited below the high tide line by the remarkable reduction of the current velocity of the tsunami because of the local topography the reduction of the current velocity must have been drastic to have made the boulders hit the ground with sufficient force to split them

origin of light hydrocarbons in gases from mud volcanoes and ch4 rich emissions abstract this paper presents new chemical data of hydrocarbon rich gases discharged from mud volcanoes and ch4 rich emissions located in different areas of italy northern apennines and sicily the determination of c5 c10 alkanes cyclics and aromatics was carried out by gc ms while the main gas species and c1 c4 hydrocarbons were analyzed by gc tdc and gc fid respectively methane is by far the most abundant component of all the investigated gas emissions with the exception of part of those discharging close to mt etna volcano which are co2 rich the gas samples collected from the emilia apennine and sicily show d ch4 and 13c ch4 values typical of thermogenic gases most gases from the romagna apennine discharge methane with a biogenic isotopic signature non methane hydrocarbons of biogenic gases are almost exclusively c2 c4 alkanes with minor amounts fraction of mol mol of c4 compounds including few aromatics and cyclics likely deriving from minor thermogenic contribution not evidenced by the 13c ch4 and d ch4 values the etnean gases whose r ra and 13c co2 values indicate a strong contribution from a hydrothermal fluid source related to the nearby volcanic system show a significant enrichment of aromatics compounds up to 36 of the non methane organic gas fraction which is likely produced by catalytic reforming processes such as dehydrocyclization of alkanes the thermogenic gases from the apennines and southwestern sicily are characterized by the presence of more than 20 different cyclic compounds with concentrations up to several mol mol cyclic compounds are likely formed by i thermal cracking and ii uncompleted aromatization of alkanes occurring at depth 3 km and temperatures not exceeding 120 150 c

tropical circulation and hydrological cycle response to orbital forcing the intensity of the two major atmospheric tropical circulations the hadley and walker circulation has been analyzed in simulations with the kiel climate model kcm of the early eemian and the early holocene both warmer climate epochs compared to the late holocene or pre industrial era the kcm was forced by changes in orbital parameters corresponding to the early and late holocene 9 5kyr bp and pre industrial and the early eemian 126kyr bp an intensification of the southern hemisphere sh winter hadley cell and a northward extension of its rising branch the intertropical convergence zone relative to pre industrial are simulated for both warm periods the walker circulation s rising branch is shifted westward towards the indian ocean due to an increased zonal tropical sea surface temperature sst gradient across the indo pacific ocean which drives enhanced easterlies over this region the simulated vertically integrated water vapor transport across the equator shows the strongest response for the sh winter boreal summer hadley cell over the pacific ocean due to an enhanced cross equatorial sst gradient in the tropical pacific during the early holocene and the early eemian the orbitally induced increase of the cross equatorial insolation gradient in the tropical pacific leads to a strengthening weakening of the wind speed and enhanced reduced evaporative cooling over the southern northern tropical pacific which reinforces the initial radiatively forced meridional sst gradient change the increased cross equatorial insolation gradient in combination with the strong wind evaporation sst feedback and changing humidity are important mechanisms to enhance the sh winter hadley circulation response to orbital forcing key points intensification of the sh winter hadley cell for the early holocene and eemian walker circulation s rising branch is shifted westward towards the indian ocean wes feedback plays key role in intensification of the hadley circulation

benthic foraminiferal evidence for the formation of the holocene mud belt and bathymetrical evolution in the central adriatic sea detailed analyses of modern and fossil benthic foraminiferal assemblages collected in the central adriatic sea are used as tools to reconstruct the environmental changes that occurred between the last deglaciation and the present last 14 kyrs in particular we focus on the timing and formation of the mud belt the modern benthic foraminiferal assemblages display a parallel zonation to the italian coast controlled by the interaction between food oxygen availability and water depth cluster analysis of 4 sediment cores separates the fossil foraminiferal assemblages in 6 groups cluster a is dominated by three ammonia species cluster b consists of ammonia papillosa nonionella turgida elphidium advenum and elphidium decipiens cluster c is composed of two taxa hyalinea balthica and trifarina angulosa cluster d is dominated by 5 species cibicides lobatulus buccella granulata reussella spinulosa textularia agglutinans and elphidium crispum cluster e contains bulimina spp gavelinopsis praegeri bolivina spp cassidulina neocarinata and asterigerinata mamilla and cluster f is dominated by bulimina marginata valvulineria bradyana globocassidulina subglobosa and melonis padanum the cluster analysis and contemporary distribution patterns of these taxa are used together with ecological preferences of the most frequent species to reconstruct the spatial and temporal distribution of the different biofacies in the past this reveals information about holocene palaeoenvironmental changes that are related to water depth fluctuations and the installment of the coast parallel mud belt the benthic assemblage records the transition from a infralitoral environment biofacies i to deeper marine condition biofacies iii after that the sea level reached about the modern level biofacies iv the benthic foraminiferal community evidences the development of the mud belt and the subsequent transformation of the ecological niches linked to the trophic evolution of the environment

evidence of subsurface anaerobic biodegradation of hydrocarbons and potential secondary methanogenesis in terrestrial mud volcanoes abstract the assessment of gas origin in mud volcanoes and related petroleum systems must consider post genetic processes which may alter the original molecular and isotopic composition of reservoir gas beyond eventual molecular and isotopic fractionation due to gas migration and microbial oxidation investigated in previous studies we now demonstrate that mud volcanoes can show signals of anaerobic biodegradation of natural gas and oil in the subsurface a large set of gas geochemical data from more than 150 terrestrial mud volcanoes worldwide has been examined due to the very low amount of c 2 in mud volcanoes isotopic ratios of ethane propane and butane generally the best tracers of anaerobic biodegradation are only available in a few cases however it is observed that 13 c enriched propane is always associated with positive 13 c co2 values which are known indicators of secondary methanogenesis following anaerobic biodegradation of petroleum data from carbon isotopic ratio of co 2 are available for 134 onshore mud volcanoes from 9 countries azerbaijan georgia ukraine russia turkmenistan trinidad italy japan and taiwan exactly 50 of mud volcanoes all releasing thermogenic or mixed methane show at least one sample with 13 c co2 5 pdb thermogenic ch 4 associated with positive carbon isotopic ratio of co 2 generally maintains its 13 c enriched signature which is therefore not perturbed by the lighter secondary microbial gas there is however high variability in the 13 c co2 values within the same mud volcanoes so that positive 13 c co2 values can be found in some vents and not in others or not continuously in the same vent this can be due to high sensitivity of 13 c co2 to gas water rock interactions or to the presence of differently biodegraded seepage systems in the same mud volcano however finding a positive 13 c co2 value should be considered highly indicative of anaerobic biodegradation and further analyses should be made especially if mud volcanoes are to be used as pathfinders of the conditions indicative of subsurface hydrocarbon accumulations in unexplored areas

waves coastal boulder deposits and the importance of the pre transport setting the pre transport environment of a coastal boulder along with its shape size and density determines the height of wave required for it to be transported different forces act on sub aerial boulders as opposed to submerged boulders when struck by a wave boulders derived from joint bounded blocks on shore platforms predominantly experience lift force and require a wave of greater height to be transported than boulders in other environments no one equation is applicable to determine the height of palaeo waves responsible for depositing a field or ridge of imbricated coastal boulders a range of equations and their derivation is presented here which can be applied to the respective pre transport environment of a boulder such an approach is necessary when attempting to reconstruct the frequency and magnitude of past coastal wave hazards and for differentiating between tsunami and storm wave deposited boulder fields

concepts in gravel beach dynamics abstract the dominant processes in gravel beach dynamics are reviewed highlighting some common themes which unify the various components of the gravel beach system the repercussions of which impart on how gravel beach dynamics might be understood conceptually in particular gravel beach dynamics are thought to be highly dependent on the temporal and spatial variation in grain size and the continual adjustments made by an active beach step both of which act not only as the expression of changing morphodynamic conditions but also as a controlling influence morphodynamics the notion that the exchanges on beaches between the hydrodynamics sediment transport and morphological change takes the form of reciprocal relationships which are mediated through feedback mechanisms in such a way that they cannot be thought of or studied independently is not a new one yet it appears that for the gravel beach morphodynamics must be re defined to describe conditions where variations in sediment size are thought to deserve parity rather than as merely a sequent entity or boundary condition morpho sedimentary dynamics is a phrase coined to intuit such cause and effect detailing the co evolution of morphology hydro hydraulics and sediment properties whilst acknowledging causative pluralism feedbacks and multiplier effects this is the recommended conceptual framework within which to crystallise thought and organise further research for the gravel beach essentially it increases the minimum number of parameters needed to describe the state of the gravel beach as a physical system therefore it is advised that simplicity will be most expedient in our future modelling efforts if complexity is to be adequately encapsulated

seismogenic sources in the adriatic domain abstract we present an overview of the seismogenic source model of the adriatic domain included in the latest version of the diss database http diss rm ingv it diss and in the european share database http diss rm ingv it share the model consists of composite and individual seismogenic sources located inside and along the margins of the adria plate in order to locate and parameterize the sources we integrated a wide set of geological geophysical seismological and geodynamic data either available from published literature or resulting from our own field work seismic profile interpretations and numerical modelling studies we grouped the sources into five regions based on geometrical and kinematic homogeneity criteria seismogenic sources of the central western adriatic north eastern adriatic eastern adriatic and central adriatic regions belong to the northern apennines external dinarides and offshore domains respectively they are characterized by nw se strike reverse to oblique kinematics and shallow crustal seismogenic depth seismogenic sources of the southern western adriatic region instead are e w striking dextral strike slip faults cutting both the upper and lower crust the fastest moving seismogenic sources are the most southern thrusts of the eastern adriatic and the strike slip sources of the southern western adriatic while the seismogenic sources of the central adriatic exhibit the lowest slip rates estimates of maximum magnitude are generally in good agreement with the historical and instrumental earthquake records except for the north eastern adriatic region where seismogenic sources exhibit a potential for large earthquakes even though no strong events have been reported or registered all sources included in the database are fully geometrically and kinematically parameterized and can be incorportaed in seismic hazard calculations and earthquake or tsunami scenario simulations

relationships between seepage tectonics and subsurface petroleum reserves abstract the relationship between visible petroleum seepage and commercial subsurface reserves has been investigated by a study of the distribution of documented seeps in south east asia this is accompanied and integrated with a broader global study the intensity of flowing seepage is controlled largely by present day tectonics and by the timing of petroleum migration when such influences are reduced by isolating sets of tectonically similar basins correlations are found between numbers of seeps and basin reserves at a sub basinal scale seeps are observed to concentrate over tectonic features such as active diapirs active faults and uplifted basin margins it is relatively rare for seeps to directly overlie major fields although many seeps may be linked to downdip accumulations by long tortuous paths the best seep accumulation relationships are observed in active compressional and diapiric settings particularly those involving shallow reservoirs seeps are rare where traps are buried beneath thick undisturbed overburdens the prime value of visible seeps in most frontier basins lies at the regional level in the clues they give to the nature extent and quantitative hydrocarbon potential of a basin s source system

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

deep seated hydrocarbons in the seep brecciated limestones of the maiella area adriatic foreland basin evaporitic sealing and oil re mobilization effects linked to the drawdown of the messinian salinity crisis abstract the 13c depleted brecciated limestones record a hydrocarbon seep event that occurred between 5 56 and 5 532 ma in the maiella area they unconformably overlie the primary lower gypsum and crop out as carbonate buildups and authigenic patches fed by fluid migration pathways filled with flow mobilized pelites tar occurs as solid bitumen shows corresponding to pore filling tar in the microfacies and as a distinctive brown facies resulting in finely impregnating patterns in thin section geochemical rock characterization confirmed that the measured total organic carbon with values up to 11 07 mostly consists of migrated hydrocarbons in the carbonate buildups and the authigenic patches while the flow mobilized pelites are devoid of oil traces bitumen characterization showed an overall homogeneity among the samples established by their similarities in the tricyclic fraction and their uniform bitumen 13c signals 26 3 28 66 pdb 1 gas chromatography mass spectrometry revealed five distinctive markers indicative of an oil that originated and migrated from a carbonate source rock high c29 c30 hopane ratio low ts tm ratio abundant c24 tetracyclic terpane absence of diasteranes and occurrence of methylsteranes considering the regional source rock setting the carbonate source rock might presumably be upper triassic lower liassic in age we favor a conceptual model that envisages a step wise migration of hydrocarbons which originated from a deep seated source and migrated through a hydrofractured reservoir bolognano fm the primary lower gypsum of the messinian salinity crisis provided an efficient seal until the major evaporative drawdown of the mediterranean sea at 5 55 ma triggered a renewed hydrocarbons migration which occurred first with a vigorous gaseous release and then with a seeping oil flow oil impregnated the early cemented brecciated limestones and partly contributed to their precipitation whereas a self clogging effect supposedly prevented oil impregnation in correspondence with the feeder channels formed during the first gaseous migration phase

late holocene foraminifera of blake ridge diapir assemblage variation and stable isotope record in gas hydrate bearing sediments abstract the presence of gas hydrates on the blake ridge diapir northeastern atlantic ocean offers an opportunity to study the impact of methane seepage on the ecology and geochemistry of benthic foraminifera in the late holocene three push cores covering a time span of 1000 yrs were retrieved from three distinct microhabitats at the top of the diapir at a water depth of 2150 m i sediments away from seepage control core ii sediments overlain by clusters of methanotrophic and thiotrophic bivalves and iii chemoautotrophic microbial mats the foraminiferal assemblages at the two seep sites are marked by a reduction in benthic foraminiferal species diversity coupled with a near absence of agglutinated species however an opportunistic population rise in ch4 or h2s tolerant calcareous species e g globocassidulina subglobosa and cassidulina laevigata that utilize the abundant trophic resources at the seeps has led to an increase in the overall assemblage density there the 18o and 13c values of three species of benthic foraminifera gyroidinoides laevigatus globocassidulina subglobosa and uvigerina peregrina and the planktonic species globorotalia menardii were acquired from all three cores the benthic species from methane seeps yield 13c values of 0 1 to 4 2 vpdb that are distinctly more 13c depleted relative to the 13c of 0 4 to 1 0 vpdb at the control off seep site the species from a mussel bed site exhibit more negative 13c values than those from microbial mats possibly reflecting different food sources and higher rate of anaerobic oxidation of methane the positive 13c values in the paired planktonic species suggest that authigenic carbonate precipitation did not overprint the observed 13c depletions hence the probable cause of negative 13c of benthic foraminifera is primary calcification from dissolved inorganic carbon dic containing mixed carbon fractions from a highly 13c depleted microbially oxidized methane and b a seawater source

paleoenvironmental reconstruction of late quaternary succession by foraminiferal assemblages of three cores from the san benedetto del tronto coast central adriatic sea italy new shelf records based on benthic foraminiferal assemblages allowed reconstruction of the paleoenvironmental evolution of the central adriatic sea during the late quaternary four distinct assemblages related to four different environments were identified based on multivariate analyses cluster analysis and principal component analysis circalittoral shallow water with vegetation deltaic and shallow marine with riverine influence two main phases were recognized by comparing the study area with the northern and southern portion of the adriatic basin the first phase was characterized by the last glacial lowstand or the beginning of the last pleistocene transgression the foraminiferal assemblage distribution was controlled by sea level changes and by the location of the ancient po river delta likely placed at the northern margin of the mid adriatic deep a subsequent deepening from a deltaic to normal marine shallow water environment occurred river supply decreases consistently from the bottom to the top of the cores due to the northern migration of the po delta the second phase which occurred during the holocene was characterized by sea level stabilization and modern water circulation pattern circalittoral foraminiferal assemblage typical of the outer mud belt developed during this second phase

carbon stable isotopic composition of benthic foraminifera from pliocene cold methane seeps cascadia accretionary margin abstract cold methane seep carbonates preserve the distinctive carbon stable isotope signatures of their ambient porewaters thus facilitating the identification of methane sources and fluid migration pathways this study employs an isotopic indicator from microfossils in a diffuse fossil seep for the recognition and characterization of methane seepage in the rock record benthic foraminifera from the pliocene quinault formation western washington state are plentiful and provide a temporal link between modern and more ancient seeps stable carbon isotope analyses of individual foraminiferal tests revealed a clear distinction between seep and non seep foraminifera infaunal species globobulimina pacifica and nonion basispinatum collected from seep samples exhibited 13 c values that were highly variable and often strongly depleted values ranged from 33 1 to 55 3 pdb in g pacifica and from 2 1 to 42 9 pdb in n basispinatum the epifaunal species cibicidoides mckannai though less depleted also showed considerable variability with 13 c values ranging from 1 7 to 3 1 pdb in contrast non seep specimens were much more enriched and less variable non seep specimens of n basispinatum displayed 13 c values clustering between 0 5 and 1 5 pdb while non seep specimens of c mckannai yielded a range of 1 1 to 1 8 pdb sem analyses and oxygen isotope values of foraminiferal tests indicated minimal diagenetic alteration 13 c values from authigenic blebs small nodules with wispy indistinct boundaries ranged from 8 7 to 38 4 pdb by combining these inorganic carbonate data with the foraminiferal values the association of seep specific bivalves and the present day leakage of thermogenic methane from the nearby garfield gas mound we conclude that these foraminifera precipitated their tests in the presence of methane derived carbon thus they record pore water 13 c depletion and syn depositional fluid flow pathways near the sediment water interface in a seep system active 3 4 mya and continuing onshore and offshore today the range and degree of 13 c depletion in the pliocene microfossils is due to the heterogeneity of seepage caused by different methane sources i e thermogenic and biogenic the tortuosity of fluid migration pathways reaching the seafloor sediments and mixing of seep fluids with dissolved inorganic carbon dic and marine organic carbon

holocene changes in biome size and tropical cyclone activity around the northern south china sea abstract the south china sea scs characterized by a large continental shelf is located at the edge of the asian monsoon domain in this study two marine sediment cores from the northern scs nscs continental slope were investigated to construct composite vegetation and precipitation isotopic composition records based on the 13c and d values of plant wax n alkanes throughout the holocene last 11 200 years i e 11 2 ka the composite 13cwax record indicates an overall predominance of c3 vegetation over the last 11 2 ka before 8 ka bp higher 13cwax values are attributed to preferential wax input from grassland and wetland biomes on the exposed continental shelf after the inundation of the shelf by eustatic sea level rise until ca 8 ka bp grassland and wetland biomes suffered a major size reduction and arboreal vegetation became better represented in the 13cwax record the composite temperature corrected dwax t record suggests that moisture source variability drove precipitation isotopic composition changes during the holocene lower dwax t values before 8 3 ka bp are interpreted as a larger moisture contribution by pacific ocean tropical cyclones whereas higher dwax t values after 8 5 ka bp are interpreted as a larger moisture contribution from the indian ocean summer monsoon higher incidence of tropical cyclones in the nscs during the early holocene was related to a temporary westward shift of the western pacific warm pool and enhanced insolation over the northern hemisphere both external and internal forcing mechanisms regulated moisture source changes in east asia during the holocene

tectonically driven mud volcanism since the late pliocene on the calabrian accretionary prism central mediterranean sea abstract mud volcanoes recently discovered on the offshore calabrian arc are investigated at two sites 60 km apart in water depths of 1650 2300 m using swath bathymetry 2d 3d multichannel seismic and cores the seabed and subsurface data provide information on their formation and functioning in relation to tectonic activity during the rapid plio quaternary advance of the accretionary prism fore arc extension and thrust belt compression are seen to have involved two main phases of activity separated by a regional unconformity recording a mid pliocene 3 5 3 0 ma tectonic reorganization the two sites of mud volcanism lie in contrasting tectonic settings inner fore arc basin vs central fold and thrust belt and record differing forms of seabed extrusive activity twin mud cones and a caldera vs a broad mud pie at both sites subsurface data show that mud volcanism took place throughout the second tectonic phase since the late pliocene differing forms of mud extrusion were accompanied by subsidence to form depressions beneath and within extrusive edifices up to 1 5 km thick the basal subsidence depressions point to sources within the succession of thrusts underlying the inner to central arc consistent with microfossils within cored mud breccias from both sites that are derived from strata as old as late cretaceous these results are argued to support a model of mud volcanism in which deeply rooted fluid conduits drive a process of near surface sediment mobilization the onset of extrusive activity is inferred to have been triggered by the mid pliocene tectonic reorganization the change in stress fields which post dates the migration of frontal compression across the area by 4 ma opening pathways for the release of overpressured fluids from deep within the accretionary prism the rising fluids interacted with shallow

gas flux to the atmosphere from mud volcanoes in eastern romania gas flux measurements have for the first time been taken from vents and soil of eastern romania mud volcanoes the largest geological structures in europe releasing methane into the atmosphere in the quiescent phase the methane emission from single vents is up to 28 t yr 1 diffuse soil microseepage is of the order of 10 2 10 5 mg m 2 day 1 a total output of at least 1200 tonnes of ch4 per year can be conservatively estimated over the area investigated alone 2 3 km 2 helium fluxes are up to five orders of magnitude higher than the average flux in a stable continental area pointing to a close link between mud volcanoes and crustal degassing through faults crossing the deep hydrocarbon reservoirs these data represent a key contribution towards refining global ch4 emission estimates which indicate mud volcanoes as a significant and unavoidable source of greenhouse gases for the atmosphere