the submerged paleolandscape of the maltese islands morphology evolution and relation to quaternary environmental change after the end of the last glacial maximum 450 km2 of former terrestrial and coastal landscape of the maltese islands was drowned by the ensuing sea level rise in this study we use high resolution seafloor data multibeam echosounder data seismic reflection profiles and remotely operated vehicle imagery and bottom samples to reconstruct 300 km2 of this submerged maltese paleolandscape the observed paleolandscape is exceptionally well preserved and comprises former coastal landforms i fault related escarpments ii paleoshore platforms and associated shorelines iii paleoshoreline deposits and iv mass movement deposits and former terrestrial landforms v river valleys vi alluvial plains vii karstified limestone plateaus and viii sinkholes these elements indicate that the paleolandscape has been primarily shaped by tectonic activity combined with fluvial coastal slope instability and karstic processes these are the same processes the shaped the current terrestrial and coastal landscape by correlating the identified landforms with the timing of known changes in sea level during the last glacial cycle we infer that the alluvial plains and the shallowest limestone plateaus had up to 100 kyr to develop whereas the paleoshoreline deposits are likely to have formed between 28 kyr and 14 kyr the most prominent paleoshore platforms shorelines and river valleys were generated between 60 kyr and 20 kyr fluvial erosion is likely to have been prevalent during periods of low sea level last glacial maximum and stadial conditions during mis 3 whereas karst processes should have been more effective during warm and humid interstadial periods our results have implications for improving the characterization of past environments and climates as well as providing a much needed background for prehistoric and geoarcheological research in the central mediterranean region

geologic structure and neotectonics of the north african continental margin south of sicily abstract marine geological and geophysical data together with drilling information indicate that the north african passive continental margin has been subjected to extension and wrenching after it collided with the northern part of sicily the area of the tripolitania basin jarrafa trough melita and medina bank and the ragusa malta plateau has formed part of a sinking passive margin since the dispersal of gondwanaland at about 180 my ago as observed from geohistory diagrams a record of rifting in a nw se direction accompanied by dextral shear along the southern troughs is observed in seismic reflection data the rifting started during the neocomian and lasted until the eocene when activity became minor a pre middle miocene period of northward subduction of oceanic crust is inferred from the geology in ne sicily uplift of the northern part of the african margin after collision in the middle miocene is seen in wells in southern sicily after the messinian a rift and dextral shear zone established itself across the african margin from the strait of sicily to the medina ridge in the lonian basin the zone is marked by up to 1 7 km deep grabens narrow active wrench faulted channels volcanic fissures and local uplifted keilhorsts such as malta this zone which varies in width from 100 to 35 km forms the southern boundary of a microplate which includes sicily we speculate that the present motion of this microplate is partly due to the eastward movement of the calabrian arc with the sicilian block over the last remaining oceanic lithosphere in the eastern mediterranean

diagenetic barium cycling in black sea sediments a case study for anoxic marine environments high resolution sedimentary records of major and minor elements al ba ca sr ti total organic carbon toc and profiles of pore water constituents view the mathml sourceso42 ch4 ca2 ba2 mg2 alkalinity were obtained for two gravity cores core 755 501 m water depth and core 214 1686 m water depth from the northwestern black sea the records were examined in order to gain insight into the cycling of ba in anoxic marine sediments characterized by a shallow sulfate methane transition smt as well as the applicability of barite as a primary productivity proxy in such a setting the ba records are strongly overprinted by diagenetic barite baso4 precipitation and remobilization authigenic ba enrichments were found at both sites at and slightly above the current smt transport reaction modeling was applied to simulate the migration of the smt during the changing geochemical conditions after the holocene seawater intrusion into the black sea based on this sediment intervals affected by diagenetic ba redistribution were identified results reveal that the intense overprint of ba and baxs ba excess above detrital average strongly limits its correlation to primary productivity these findings have implications for other modern and ancient anoxic basins such as sections covering the oceanic anoxic events which ba is frequently used as a primary productivity indicator our study also demonstrates the limitations concerning the use of baxs as a tracer for downward migrations of the smt due to high sedimentation rates at the investigated sites diagenetic barite fronts are buried below the smt within a relatively short period thus relict barite fronts would only be preserved for a few thousands of years if at all

the calabrian stage pleistocene highstand in malta a new marker for unravelling the late neogene and quaternary history of the islands abstract the late neogene and quaternary sedimentary record within the maltese islands is very fragmentary and has generally been ignored by sedimentologists local stratigraphies for parts of the quaternary have been erected from vertebrate remains contained in quaternary cave and fissure deposits of the islands however no coherent correlation scheme has been proposed in which to encompass them the situation is exacerbated by the absence of datable fossils within the majority of quaternary deposits considerable progress in resolving these problems is however possible if recourse is made to the post messinian late miocene erosion features evidenced in the topography of the islands in particular a hitherto unrecognized marine erosion surface the san leonardo marine abrasion surface is described and dated by reference to the marine deposits san leonardo beds lying directly above it and similarities to contemporaneous se sicily marine deposits this provides an end calabrian stage emilian sub stage base line upon which to hang fragmentary information on later events that have shaped the topography of the maltese islands from this it can be confirmed that a tectonic deformation event spanning latest messinian to mid pliocene times uplifted the islands and reactivated previously incipient graben systems this deformation episode is shown to have ceased within the islands well before the early calabrian before c 1 6 ma subsequent minor regional uplift and eustacy together with subaerial weathering processes have been the principal agents in shaping the islands collectively these processes have prevented terrestrial animal migrations into the maltese islands from north africa since messinian times however the infrequent re establishment of a marine lowstand isthmus virtually linking malta with se sicily has permitted opportunistic animal migrations into the islands and the presence of these greatly aids in dating the sedimentological events

variability in sulfur isotope records of phanerozoic seawater sulfate the s of seawater sulfate reflects processes operating at the nexus of sulfur carbon and oxygen cycles however knowledge of past seawater sulfate s values must be derived from proxy materials that are impacted differently by depositional and post depositional processes we produced new timeseries estimates for the s value of seawater sulfate by combining 6710 published data from three sedimentary archives marine barite evaporites and carbonate associated sulfate with updated age constraints on the deposits robust features in multiple records capture temporal trends in the s value of seawater and its interplay with other phanerozoic geochemical and stratigraphic trends however high frequency discordances indicate that each record is differentially prone to depositional biases and diagenetic overprints the amount of noise quantified from the variograms of each record increases with age for all s proxies indicating that post depositional processes obscure detailed knowledge of seawater sulfate s s value deeper in time

multiproxy assessment of holocene relative sea level changes in the western mediterranean sea level variability and improvements in the definition of the isostatic signal abstract a review of 917 relative sea level rsl data points has resulted in the first quality controlled database constraining the holocene sea level histories of the western mediterranean sea spain france italy slovenia croatia malta and tunisia we reviewed and standardized the geological rsl data points using a new multi proxy methodology based on 1 modern taxa assemblages in mediterranean lagoons and marshes 2 beachrock characteristics cement fabric and chemistry sedimentary structures and 3 the modern distribution of mediterranean fixed biological indicators these rsl data points were coupled with the large number of archaeological rsl indicators available for the western mediterranean we assessed the spatial variability of rsl histories for 22 regions and compared these with the ice 5g vm2 gia model in the western mediterranean rsl rose continuously for the whole holocene with a sudden slowdown at 7 5 ka bp and a further deceleration during the last 4 0 ka bp after which time observed rsl changes are mainly related to variability in isostatic adjustment the sole exception is southern tunisia where data show evidence of a mid holocene high stand compatible with the isostatic impacts of the melting history of the remote antarctic ice sheet our results indicate that late holocene sea level rise was significantly slower than the current one first estimates of gia contribution indicate that at least in the northwestern sector it accounts at least for the 25 30 of the ongoing sea level rise recorded by mediterranean tidal gauges such contribution is less constrained at lower latitudes due to the lower quality of the late holocene index points future applications of spatio temporal statistical techniques are required to better quantify the gradient of the isostatic contribution and to provide improved context for the assessment of 20th century acceleration of mediterranean sea level rise

sulfur isotopes track the global extent and dynamics of euxinia during cretaceous oceanic anoxic event 2 the mesozoic era is characterized by numerous oceanic anoxic events oaes that are diagnostically expressed by widespread marine organic carbon burial and coeval carbon isotope excursions here we present coupled high resolution carbon and sulfur isotope data from four european oae 2 sections spanning the cenomanian turonian boundary that show roughly parallel positive excursions significantly however the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years based on geochemical box modeling of organic carbon and pyrite burial the sulfur isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic i e anoxic and sulfidic water column conditions to replicate the observed isotopic offset the model requires that enhanced levels of organic carbon and pyrite burial continued a few hundred thousand years after peak organic carbon burial but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater the significant inference is that euxinia persisted post oae but with its global extent dwindling over this time period the model further suggests that only 5 of the global seafloor area was overlain by euxinic bottom waters during oae 2 although this figure is 30 greater than the small euxinic fraction present today 0 15 the result challenges previous suggestions that one of the best documented oaes was defined by globally pervasive euxinic deep waters our results place important controls instead on local conditions and point to the difficulty in sustaining whole ocean euxinia

lithofacies and faunal succession faunal phase analysis as a tool in unravelling climatic and tectonic signals in marginal basins messinian miocene sicily many basins are filled under the influence of tectonics and variable climatically driven processes unravelling the relative contributions of these is generally easier in fossiliferous sequences if faunal diversity patterns are considered in conjunction with lithofacies analysis this approach has been successfully applied to late miocene strata of sicily where progressive restriction and desiccation within the sicilian caltanissetta region occurred under a semi arid climate during the messinian stage this restriction was partly due to antarctic cooling which produced palaeo mediterranean sea level oscillations during the early messinian as a prelude to closure of the atlantic connections in addition regions within this afro european plate collision zone were also subjected to syndepositional tectonic deformation associated with progressive perched basin development above foreland south verging thrust sheets the relative impacts of climatic eustatic versus tectonic control on sedimentation patterns within these perched basins has been debated at length however progress towards resolving this problem by a combined approach involving lithofacies analysis and faunal phase analysis provides clues for separating the effects of the controlling factors faunal phase analysis identifies general faunal associations with minimal emphasis on species diversity the resulting phase plots for early messinian strata appear to be transgression skewed when controlled by eustatic cyclicity and regression skewed when driven by regional tectonics associated with perched basin tectonics

a revised seawater sulfate s isotope curve for the eocene abstract the sulfur isotope ratio 34s recorded in marine barite is commonly used to estimate secular changes in the sulfur isotopic composition of seawater sulfate 34sso4 throughout earth s history the cenozoic record demonstrates a drastic 5 increase in seawater 34sso4 during the early eocene however the gradient of this excursion is based on only a few data points taking advantage of a much improved biostratigraphic framework we redefine the eocene 34sso4 data with a new high resolution barite based 34s record between 60 and 30 ma our results show that the rise of 34sso4 starts about 3 million years later 53 ma and lasts about 9 million years longer until 38 ma than previously depicted as such the gradient of the 34s curve is 0 4 myr the radiogenic strontium isotopic ratio in barite suggests that some of the samples used for the original barite record are affected by diagenetic alteration

high resolution record of export production in the eastern equatorial pacific across the eocene oligocene transition and relationships to global climatic records 1 understanding changes in export production through time provides insight into the response of the biological pump to global climate change particularly during periods of rapid climate change in this study we consider what role changes in export production may have had on carbon sequestration and how this may have contributed to the onset of the eocene oligocene transition eot in addition we consider if these export production variations are dominantly controlled by orbitally driven climate variability to accomplish these objectives we report changes in export production in the eastern equatorial pacific eep from site u1333 across the eot reconstructed from a high resolution record of marine barite accumulation rates bar bar fluctuations suggest synchronous declines in export production associated with the two step increases in oxygen isotopes that define the transition the reduction in productivity across the eot suggests that the biological pump did not contribute to carbon sequestration and the cooling over this transition we also report a previously undocumented peak in eep export productivity before the eot onset this peak is consistent with export production proxies from the southern ocean potentially implying a global driver for this precursor event we propose that this enhanced export production and the associated carbon sequestration in the late eocene may have contributed to the pco2 drawdown at the onset of antarctic glaciation

pleistocene mammals of mediterranean islands abstract this paper provides a synthesis and an integration of the current knowledge on pleistocene mammals from the main mediterranean islands new evidence enables us to consider faunal complexes paleobiodiversity degree of endemism and ways of dispersals into a chronological frame the balearic islands developed an endemic fauna from mainland ancestors spreading during the messinian sardinia and corsica have had a pliocene early pleistocene fauna spread from mainland during the messinian the arrivals after this time can be related to occasional spreading during the early pleistocene and early middle pleistocene sicily and malta acted as an archipelago made up of small islands since late middle pleistocene sicily has been a large island with frequent faunal exchanges with the mainland during early pleistocene and early middle pleistocene crete was an archipelago occasionally reached by mammals communications with the mainland have probably been easier since the late middle pleistocene cyprus has been completely isolated and developed a strongly endemic and impoverished fauna

a neogene seawater sulfur isotope age curve from calcareous pelagic microfossils abstract until now our knowledge of the sulfur isotopic composition of seawater through geologic time has depended on stable isotopic analysis of sulfate from evaporites owing to the sporadic occurrence of evaporites through time the secular sulfur isotope age curve contains many gaps with little or no data in order to fill in some of these gaps particularly the neogene we have analyzed the sulfur isotopic composition of carbonate associated sulfate in carbonate tests of planktonic foraminifera other investigators have shown that sulfate may occur in biogenic calcites either lattice bound as micro fluid inclusions in adsorbed phases or as protein polysaccharides whatever the origin the sulfur isotopic composition of this sulfate appears to be representative of that of the water in which the organism lived as shown by results on recent calcareous foraminifera and macrofossils using this approach for study of miocene to recent pelagic marine sediments supplemented by new data for miocene marine evaporites from the gulf of suez we have found that the 34 s of seawater has decreased about 2 5 over the past 25 m y and that most of the decrease has occurred over the past 5 m y parallelling a decrease in the 13 c of dissolved oceanic bicarbonate from the same interval sedimentary redox models based on isotope records suggest that organic carbon and sulfide burial have both decreased over the past 5 m y alternatively an increase in weathering rates over the past 5 m y would not require a decrease in organic carbon or sulfide burial as long as the isotopic effect of the increased river input exceeds the isotopic effect of the burial of the reduced species in either case the net result would be a decrease in atmospheric p o 2

the monte carrubba formation messinian sicily and its correlatives new light on basin wide processes controlling sediment and biota distributions during the palaeomediterranean mediterranean transition abstract a little known marine miocene messinian succession in the hyblean region of south eastern sicily preserves a carbonate ramp sequence which developed on the tectonically stable foreland margins of the african plate pelagian block the ramp monte carrubba formation was distally steepened and contained a shoalwater barrier and lagoonal inner ramp complex the outer ramp is poorly preserved though distal deep water ramp facies tellaro formation in the south hyblean region preserve a full globorotalia mediterranea subzone and major part of the globigerina multiloba subzone succession this ramp sequence faithfully records the subtle interplay between the global eustatic curve and internal palaeomediterranean base level signatures for the late miocene the earliest second order palaeomediterranean lowstand occurred in the late tortonian at about 7 3 ma and a second occurred at about 6 75 ma within the early messinian g mediterranea subzone both were in the order of 40 m and global sea level was probably restored to the palaeomediterranean after the lowstands although the overriding control at the time was the global eustatic curve harmonic discrepencies between it and the palaeomediterranean curve resulted from constriction of the atlantic connection during the latest tortonian from about 6 4 ma until about 5 96 ma increasingly restricted conditions developed across the monte carrubba inner ramp these faithfully reflect many second order constriction driven palaeomediterranean sea level oscillations which were superimposed on to the falling global signal as the connecting atlantic seaways became constricted these oscillations resulted in major reductions in planktonic faunal diversity within the outer ramp followed by total emergence of the inner ramp by about 6 05 ma marine deposition continued until about 5 96 ma in the southern part of the hyblean region however between 6 05 ma and about 5 6 ma the amplitude of successive palaeomediterranean sea level oscillations increased to over 100 m causing prolonged periods of total palaeomediterranean isolation the hyblean carbonate suite also contains post messinian salinity crisis post msc lago mare highstand deposits which are developed unconformably above the monte carrubba formation the widespread distribution of hyposaline to near marine congeria faunas within the lago mare episode argues for high post msc mediterranean water levels in the central mediterranean late messinian in this article we draw together disparate regional evidence from this stable foreland setting and assimilate it with published data from regions lying on the european plate in order to demonstrate that the tectonically stable monte carrubba succession provides an unambiguous record of central palaeomediterranean base level change during the messinian furthermore the post msc sequence demonstrates a prolonged mediterranean base level rise throughout the late messinian leaving little readjustment necessary in order to restore mediterranean base level to global water levels in basal pliocene times

holocene sea level change in malta abstract a multidisciplinary approach has been applied to study sea level changes along the coast of malta using data collected from underwater archaeological remains the elevation of archaeological markers have been compared with predicted sea level curves providing new bodies of evidence that outline the vertical tectonic behaviour of this region allowing estimation of the relative sea level changes that occurred in this area of the mediterranean since the bronze age during the roman age sea level was at 1 36 0 1 m while in the midde age it was at 0 56 0 2 m in agreement with previous estimations for the mediterranean region data indicate that malta was tectonically stable during the studied period the occurrence of the present day notch along the coasts of the island indicates recent vertical stability of the area the lack of mis 5 5 deposits all over the island could simply be due to high rates of erosion as its coasts are highly exposed to storm waves rather than tectonic movements however even very slight vertical movements could completely remove field evidence the relative stability of the maltese islands allowed a first attempt to provide a palaeoenvironmental reconstruction of its coasts at different time windows since the last glacial maximum the results have been used to infer time and mode of mammal dispersal to the island during the pleistocene

syndepositional tectonics affecting cenozoic and mesozoic deposition in the malta and se sicily areas central mediterranean and their bearing on mesozoic reservoir development in the n malta offshore region abstract tertiary sedimentation patterns within the maltese islands and se sicily pelagian block of the central mediterranean reflect subtle depositional control by the concurrent evolution of the malta graben lying to the south west and reactivation of regionally important mesozoic fault systems the visible structural style of the maltese islands is the product of malta graben development and commenced some 24 million years ago however north south oriented structures identified from maltese tertiary facies strike patterns can be closely related to reactivated mesozoic faults in se sicily here synsedimentary tectonogenesis is recognized in both mesozoic and cenozoic strata mesozoic synsedimentary faulting was initiated during a former tectonic regime when the pelagian block african plate lay at the southern side of a wide tethys ocean reactivation of these fractures during the tertiary is believed to be related to subsequent african european plate collision the unsuccessful oil search in maltese territorial waters results from the mistaken significance attached to the young malta graben related tectonic pattern of the maltese islands potential traps are more likely to be associated with a cryptic though formerly dominant mesozoic tectonic pattern the hypothesis presented predicts hydrocarbon prospects in horst traps immediately to the north of the malta shelf these can be expected to show many of the characteristics of the gela and ragusa fields

multiple sulfur isotope constraints on the modern sulfur cycle we present 28 multiple sulfur isotope measurements of seawater sulfate 34sso4 34sso4 and 33sso4 33sso4 from the modern ocean over a range of water depths and sites along the eastern margin of the pacific ocean the average measured 34sso4 34sso4 is 21 24 0 88 2 0 88 2 with a calculated 33sso4 33sso4 of 0 050 0 050 0 014 2 0 014 2 with these values we use a box model to place constraints on the gross fraction of pyrite burial in modern sediments this model presents an improvement on previous estimates of the global pyrite burial flux because it does not rely on the assumed value of 34spyrite 34spyrite which is poorly constrained but instead uses new information about the relationship between 34s 34s and 33s 33s in global marine sulfate our calculations indicate that the pyrite burial flux from the modern ocean is between 10 and 45 of the total sulfur lost from the oceans with a more probable range between 20 and 35

sulfur isotope ratios in co occurring barite and carbonate from eocene sediments a comparison study abstract in order to investigate the utility of bulk carbonate as a recorder of seawater sulfate sulfur isotope ratios 34ssw co existing pelagic barite and bulk carbonate in eocene sediments from the equatorial pacific ocean iodp exp 320 321 sites u1331 to u1333 were analyzed for their sulfur isotope ratios 34s the 34s from both minerals showed parallel fluctuation throughout the eocene with carbonate associated sulfate cas values about 0 8 heavier than those of barite a similar offset was observed in cas 34s obtained using species specific cleaned planktonic foraminifers in a previous study the consistent results from two distinct minerals suggest that the original 34ssw can be derived from bulk cas analysis if post deposition carbonate recrystallization is minimal the combined data set showed a 5 increase of 34ssw during the eocene from 53 ma to 36 ma with the majority of the shift within 7 myr between 53 and 46 ma this change is more gradual than previously reported the timing of this 34ssw shift coincides with extensive pyrite burial in the arctic ocean supporting the hypothesis that the 5 increase in eocene 34ssw has been caused by 34s enriched water outflow from the arctic ocean

global geochemical cycles of carbon sulfur and oxygen time resolved data on the carbon isotopic composition of carbonate minerals and the sulfur isotopic composition or sulfate minerals show a strong negative correlation during the cretaceous carbonate minerals are isotopically heavy during this period while sulfate minerals are isotopically light the implication is that carbon is being transferred from the oxidized carbonate reservoir to the reservoir of isotopically light reduced organic carbon in sedimentary rocks while sulfur is being transferred from the reservoir of isotopically light sedimentary sulfide to the oxidized sulfate reservoir these apparently oppositely directed changes in the oxidation state of average sedimentary carbon and sulfur are surprising because of a well established and easy to understand correlation between the concentrations of reduced organic carbon and sulfide minerals in sedimentary rocks rocks rich in reduced carbon are also rich in reduced sulfur the isotopic and concentration data can be reconciled by a model which invokes a significant flux of hydrothermal sulfide to the deep sea at least during the cretaceous

cenozoic record of δ 34 s in foraminiferal calcite implies an early eocene shift to deep ocean sulfide burial understanding the changes in and drivers of isotopic variability of sulfur in seawater sulfate 34sso4 sw over geological time remains a long standing goal particularly because of the coupling between the biogeochemical sulfur and carbon cycles the early cenozoic has remained enigmatic in this regard as the existing seawater sulfate isotopic records appear to be decoupled from the well defined carbon isotope composition of the ocean here we present a new cenozoic record of sulfur isotopes using carbonate associated sulfate hosted in the calcite lattice of single species foraminifera the vastly improved stratigraphy afforded by this record demonstrates that carbon and sulfur cycles as recorded by their isotopes are not fully decoupled in the early cenozoic with a model driven by partial coupling of the carbon and sulfur cycles we demonstrate that a change in sulfur isotopic fractionation of the pyrite burial flux best explains the large increase in 34sso4 sw 53 million years ago ma and the subsequent long steady state we suggest that the locus of pyrite burial changed from shallow epicontinental seas and shelf environments to more open ocean sediments around 53 ma loss of extensive shelf environments corresponds to cretaceous palaeogene sea level changes and tectonic reorganization occurring as the himalayan arc first collided with asia a cenozoic reconstruction of the 34s of marine sulfate suggests a shift in the locus of pyrite burial from shallow seas to the open ocean during the early eocene

aridity and humidity two aspects of the late miocene climate of north africa and the mediterranean abstract the physiography of north africa is not greatly changed from that of the messinian with the drawdown of the mediterranean in the late messinian the then existing river systems were incised into the landscape and emptied into lake cyrenaica which occupied the substantially drained eastern mediterranean basin the record of incision provides a record of the magnitude of the messinian river systems an analysis of these river systems demonstrates that messinian rainfall a consequence of the zeit wet phase was greatest in east and south central north africa in keeping with the derivation of the water mainly from the indian ocean in central north africa the eosahabi river flowed from messinian lake chad eroding the east tibesti valley and cutting a channel which is especially well preserved near the coast of the gulf of sirt the penetrated sediments of lake cyrenaica and the marginal basins of the messinian transgression are known as the upper evaporites and are generally fine clastics gypsarenites and gypsum anhydrite they were rapidly deposited underlying them is the halite of the lower evaporites this sequence of upper and lower evaporites is much like the lower halite of the tortonian south gharib formation and the overlying clastics and anhydrite of the messinian zeit formation in the gulf of suez red sea area this type of sequence is termed an evaporitic couplet and as has been demonstrated for the gulf of suez red sea is a consequence of a transition from a dry to a more humid climate in a restricted or semirestricted basin this transition occurred at about 7 5 ma in the gulf of suez red sea and at about 5 8 ma in the mediterranean the zeit wet phase manifest in the above events developed in association with the initiation and development of the asian monsoon and the drying of the mediterranean it can be understood in terms of the development of an evolving monsoon desert system the asian monsoon was initiated 8 7 ma in association with the uplift of tibet at this time the north african desert zone was displaced northwards to be over the mediterranean and central and eastern north africa became seasonally humid a concept is advanced in which the early stage of the development of the asian monsoon is seen as having two phases alternating at the precessional ca 21 ka cycle one phase transferred moisture from the indian ocean mainly to southern asia the other phase transferred moisture mainly to north africa with the drawdown of the mediterranean at about 5 8 ma the zeit wet phase intensified a further northward movement of the humid and desert zones occurred at the time of drawdown with the messinian and early pliocene transgressions the wet phase ameliorated but a substantial river system still crossed central north africa at about 4 6 ma north africa became drier probably in response to the developing dominance of the features of the monsoon that transferred moisture mainly to southern asia features of the monsoon that are well recognised today

chronologic model and transgressive regressive signatures in the late neogene siliciclastic foundation long key formation of the florida keys abstract recent drilling of continuous cores in southernmost florida has documented a thick unit of upper neogene siliciclastics subjacent to surficial shallow water quaternary carbonates exposed on islands of the florida keys the siliciclastics comprise the long key formation and were identified in two cores collected from the middle and upper florida keys a chronologic model based on new planktic foraminiferal biochronology and strontium isotope chronology suggests the timing of siliciclastic deposition and provides a basis for regional correlation the chronologic model supplemented by vertical trends in quartz grain size pattern of planktic menardiiform coiling direction and paleoenvironmental interpretations of benthic foraminiferal assemblages shows that the long key formation contains three intervals i iii of varying thickness grain size composition and paleo water depth interval i is uppermost miocene the quartz grains in interval i fine upward from basal very coarse sand to fine and very fine sand benthic foraminifera indicate an upward shift from an outer shelf to inner shelf depositional environment interval ii deposited during the late early to early late pliocene contains reworked upper miocene siliciclastics and faunas in the upper keys quartz grains in interval ii range from very coarse sand that fines upward to very fine sand and then coarsens to very coarse and medium sand in situ benthic faunas indicate an upward shift from outer shelf to inner shelf deposition in the middle keys interval ii is different with the quartz grains ranging primarily from medium to very fine sand in situ benthic taxa indicate deposition on an inner shelf in both the middle and upper keys the upper pliocene siliciclastics of interval iii contain quartz grains ranging from very coarse to very fine sands that were deposited on an inner shelf a sequence boundary between interval i and interval ii is suggested by an abrupt shift in the strontium isotope chemostratigraphy coarsening in quartz grain size above the boundary an abrupt landward shift in depositional facies in the upper keys core and a distinct variation in the predominant coiling direction of the menardiiform planktic foraminifera from fluctuating dextral sinistral to dextral in the upper keys core successive siliciclastic infilling likely associated with eustatic sea level change and current redeposition formed a foundation for subsequent carbonate deposition deep sea biostratigraphic techniques integrated with ages derived from strontium isotope chemostratigraphy can be successfully applied to coastal margin sequences even though a depauperate suite of faunal markers is common

constraints on lithospheric thermal structure for the indian ocean from depth and heat flow data models for the thermal evolution of oceanic lithosphere are primarily constrained by variations in seafloor depth and heat flow with age these models have been largely based on data from the pacific and atlantic ocean basins we construct seafloor age relations for the indian ocean which we combine with bathymetric sediment isopach and heat flow data to derive curves for depth and heat flow versus age comparison of these curves with predictions from three thermal models shows that they are better fit by the shallower depths and higher heat flow for the gdh1 model which is characterized by a thinner and hotter lithosphere than previous models

the sulphur isotopic composition of trace sulphates in carboniferous brachiopods implications for coeval seawater correlation with other geochemical cycles and isotope stratigraphy the carboniferous 34s record based on the analysis of structurally substituted sulphate sss in brachiopod shells is characterized by a significant decline from values around 21 1 in the tournaisian to 12 1 in the gzelian superimposed on this broad evolution is a higher order structure with a relative minimum in the late visean followed by a maximum in the bashkirian on the 107 year time scale 34s is positively correlated with 13ccarb in contrast to the long term negative linkage between sulphur and carbon observed for the entire phanerozoic this indicates that mechanisms other than the redox balance control the carbon and sulphur cycles on this time scale the 87sr 86sr and 34s records display parallel trends during the tournaisian to moscovian this positive correlation suggests that tectonics may be of importance for the evolution of 34s on time scales of 107 years a possible scenario to explain the co evolution of the isotope systems and their linkage to tectonism and palaeoclimate invokes an increased nutrient supply to the oceans during periods of enhanced uplift and continental weathering this nutrient flux may have resulted in increased burial of organic matter and enhanced bacterial sulphate reduction

lithofacies modelling and sequence stratigraphy in microtidal cool water carbonates a case study from the pleistocene of sicily italy quaternary carbonates in se sicily were deposited in seamount and short ramp settings during glacio eustatically driven highstand conditions they provide an excellent opportunity to investigate the depositional and erosional aspects of cool water carbonate sedimentation in a microtidal marine water body the derived ramp facies model differs significantly from modern day open ocean ramp scenarios in projected facies depth ranges and in the preservation of inshore facies a sequence stratigraphic study of the carbonates has confirmed many established aspects of carbonate sedimentation e g production usually only occurred during highstands it has also revealed several new features peculiar to water bodies with little tidal influence including catch up surfaces taking the place of transgressive facies second order sequence boundary events being most important as triggers for initiating resedimentation and a virtual absence of sediment shedding to the basin during the terminal lowstand production in the carbonate factory lasted for about 0 5 myr despite this carbonate production was considerable and included both bioconstructional and bioclastic dominated facies and the production of abundant lime muds a model for eustatically controlled cool water carbonate production and resedimentation in microtidal marine water bodies is presented this is considered to be more applicable to neogene and quaternary strata in the mediterranean region than are current open ocean models

inversion of surface wave data for subsurface shear wave velocity profiles characterized by a thick buried low velocity layer the study formed part of the simit project integrated italy malta cross border system of civil protection b1 2 19 11 part financed by the european union under the italiamalta cross border cooperation programme 2007 2013

the preservation of δsso434 and δoso418 in carbonate associated sulfate during marine diagenesis a 25 myr test case using marine sediments a 25 million year record of the sulfur and oxygen isotope composition of marine carbonate associated sulfate cas was constructed from 55 nannofossil ooze samples at three different locations we tested the impact of early marine diagenesis on cas by comparing the cas extractions to the sulfur and oxygen isotope composition of the associated pore fluid sulfate to determine the degree of pore fluid incorporation during carbonate recrystallization neither the sulfur nor the oxygen isotope composition of cas are completely overprinted by incorporation of pore fluid sulfate we compare our record to the sulfur and oxygen isotope records of coeval barite the sulfur isotope record is in agreement with the barite record within 2 2 except where very young 2 ma sediments are in the presence of highly evolved pore fluid sulfate view the mathml source s34 70 a simple recrystallization model is used to illustrate the sensitivity of cas view the mathml source sso434 to sedimentation rate and to emphasize that careful sample selection along with an analysis of early diagenetic environmental conditions is crucial when interpreting cas sulfur isotopes oxygen isotopes in cas are more complex and do not reproduce similar values to those of coeval barite we conclude that oxygen isotopes in sulfate may remain a useful proxy but merit closer attention in the future

shallow high resolution geophysical investigation along the western segment of the victoria lines fault island of malta abstract the victoria lines fault island of malta is a 15 km long and n260 striking segmented normal fault system which is probably inactive since the late pliocene in the westernmost part the fomm ir rih segment displays comparable geologic throw and escarpment height 150 170 m moreover its hangingwall hosts thin patches of middle pleistocene clastic continental deposits red beds which are poorly preserved elsewhere we acquired two seismic transects by collecting ambient vibration recordings processed by using horizontal to vertical spectral ratios complemented by one high resolution 2 d refraction tomography survey crossing this fault where it is locally covered by red beds and recent colluvial deposits we found a resonance peak at 1 0 hz in the hangingwall block whereas clear peaks in the range 5 0 10 0 hz appear when approaching the subsurface fault and we relate them to the fractured bedrock within the fault zone the best fit tomographic model shows a relatively high vp shallow body vp 2200 2400 m s that we relate to the weathered top of the miocene upper coralline limestone fm bounded on both sides by low vp regions 230 m s above the weathered top bedrock our results depict a clear seismic signature of the victoria lines fault characterized by low seismic velocity and high amplification of ground motion we hypothesize that during the middle pleistocene faulting may have affected the basal part of the red beds so that this part of the investigated complex fault system may be considered inactive since 0 6 myr ago

transient cooling episodes during cretaceous oceanic anoxic events with special reference to oae 1a early aptian the two major oceanic anoxic events of the cretaceous those of the early aptian oae 1a and the cenomanian turonian boundary oae 2 registered some of the highest temperatures reconstructed for the cretaceous period and are thought to be related to the input of volcanically derived carbon dioxide from one or more large igneous provinces widely distributed deposition of marine organic matter the hallmark of oaes and intensified silicate weathering in response to a globally accelerated hydrological cycle and or reaction of seawater with freshly extruded basalt are both potential mechanisms whereby the content of atmospheric carbon dioxide could have been drawn down to promote cooling on the assumption that this potential effect was not offset by increased addition of this volcanically derived greenhouse gas reduction in the supply of such carbon dioxide with deposition of organic matter and silicate weathering continuing at the same rate could also have produced cooling a transient fall in temperature and increase in marine dissolved oxygen levels is well documented for oae 2 in the form of the so called plenus cold event or benthic oxic event associated with southward invasion of certain boreal faunas and an increase in many redox sensitive and or chalcophilic elements in seawater caused by temporary loss of anoxic euxinic sinks as basalt seawater interaction continued apace high resolution studies of oae 1a show at least three cooling episodes of probable global distribution one of which recorded in the stratigraphy of the so called c4 segment is documented at high enough resolution to show correlation with an increase in carbon isotope values that was probably due to a rise in the quantities of organic matter being buried globally with consequent potential drawdown of atmospheric co2 and or reduction in volcanic input of this greenhouse gas both calcium and lithium isotope records suggest an increase in silicate weathering over the oae 1a interval but current relatively low resolution records cannot at present be tied to any one cooling episode although the lowest li isotope values do derive from the c4 segment evidence for reoxygenation of the ocean during the transient cooling episodes of oae 1a is meagre due to the lack of suitable sedimentary archives although a negative sulfur isotope excursion in a pacific shallow water carbonate section which can be interpreted as due to oxidation of pyrite and or sulfur rich organic matter in the global ocean suggests that this phenomenon may also have been a feature of the c4 segment further work is required to elucidate the similarities and differences between oae 2 and oae 1a but both phenomena are demonstrably global in reach and represent major disturbances to the carbon cycle with attendant effects on marine temperatures this article is part of a discussion meeting issue hyperthermals rapid and extreme global warming in our geological past