seasonal variation in the flux of planktonic foraminifera time series sediment trap results from the panama basin abstract a mooring array with three automated sediment traps capable of collecting time series samples was deployed in the panama basin for one year beginning in december 1979 a series of six consecutive two month long samples was collected at each of three depths 890 2590 and 3560 m in order to examine seasonal variation in the flux of planktonic foraminifera and evaluate the contribution of foraminifera to the total carbonate flux the flux of the larger planktonic foraminifera 250 500 m and 500 1000 m is greatest during february march when upwelling is most intense in the panama basin in contrast the maximum flux of the smaller foraminifera 125 250 m is associated with a phytoplankton bloom during the summer months june through september this size dependent flux pattern appears to be a species specific effect the flux of the larger foraminifera is dominated by non spinose forms i e neogloboquadrina dutertrei and globorotalia theyeri while the flux of the smaller foraminifera consists predominantly of spinose species i e globigerinoides ruber g sacculifer and g conglobatus although the magnitude of the flux varied throughout the year the average weight of individual foraminiferal tests in different size fractions showed no seasonal variability with the exception of the june july period when there was a major coccolith bloom planktonic foraminifera greater than 125 m account for between 28 and 34 of the total carbonate flux at this location during the coccolith bloom planktonic foraminifera accounted for less than 2 of the total carbonate flux planktonic foraminifera in the 250 500 m size range are the most significant contributors to the overall particulate flux accounting for roughly 70 80 of the total foraminiferal fluxes measured at the three trap depths

changes in planktonic assemblages during sapropel s5 deposition evidence from urania basin area eastern mediterranean 1 a micropaleontological study of planktonic assemblages on the partially laminated sapropel s5 late pleistocene marine isotope stage mis 5e was performed in two piston cores from urania basin area eastern mediterranean west of crete um94pc16 and um94pc31 recovered during a paleoflux project cruise the abundance of florisphaera profunda indicates the development of a deep chlorophyll maximum dcm before the anoxic condition at bottom were established whereas patterns of upper photic zone coccoliths suggest extreme oligotrophy in surface water the short appearance of globorotalia scitula and the presence of globigerinoides ruber in the lower part of sapropel testify to a thermal stratification also recorded by changes in primary producers during g scitula occurrence diatoms mainly represented by pseudosolenia calcar avis appear and bloom because of their capability in using nutrients from dcm scanning electron microscope analyses performed on selected intervals from um94pc16 show that the sapropel is organized in microlaminae mostly composed by siliceous microfossils in particular sapropel s5 could be related to an enhanced nutrient availability in the lower middle part of the photic zone stratified conditions and a higher continental input

distribution patterns of live planktic foraminifers as related to regional hydrography and productive systems of the mediterranean sea abstract distribution patterns of live planktic foraminifers are examined at two times of the year late summer and late winter through horizontal plankton towing along a nw se transect across the west and east mediterranean basins and in the alboran sea french oceanographic cruises vicomed i ii and iii respectively foraminiferal production is significantly different in the two sampling periods and across the west and east mediterranean foraminiferal density is higher in winter than summer e g in the western basin 3700 specimens 1000 m3 in winter against 200 600 specimens 1000 m3 in summer the production averaged for the two sampling sets is higher in the western basin than in the eastern one however in late summer peaks of maximal production are observed in the central mediterranean strait of sicily and ionian basin 1000 to 2000 specimens 1000 m3 where the assemblages are dominated by globigerinoides ruber rosea and g ruber alba in the mediterranean sea frontal regions and semipermanent eddies which are essentially controlled by regional hydrography represent a significant portion of the regional production they also elicit a higher diversity of species their influence is observed in summer as well as in winter at the end of summer the rather shallow mixed layer hosts spinose symbiont bearing species such as g ruber alba g ruber rosea o universa and g trilobus at that season in the western basin the nutrient content of the mixed layer is generally low and the surface layer is rapidly nutrient depleted summer foraminiferal production remains low at the surface with respect to the winter production in the eastern basin late summer and autumn correspond to the biological spring summer foraminiferal production in surface waters is higher than in winter but standing crops are lower than in the western basin for the same species at the same period in summer however frontal structures and eddies are generally better developed than in winter in some particular cases frontal boundaries in the western basin eddies south of cyprus nutrients from intermediate layers can be upwelled through isopycnal or diapycnal mixing to the photic zone and allow for secondary blooms in the western basin these blooms favour the development of grazers at depth globorotalia truncatulinoides g inflata south of cyprus in the eastern basin oligotrophic conditions promote the development of heterotrophic organisms and predatory foraminifers have higher standing stocks g ruber alba g ruber rosea in winter the break down of the thermocline combined with deep turbulent mixing in the northwestern basin and the deepening of the mixed layer in the alboran sea and along the north african coast result in increased phytoplankton biomass and favour reproduction and proliferation of species such as g truncatulinoides or g inflata our observations indicate that the geographic and depth distribution of live foraminiferal species cannot be entirely explained by the general temperature and salinity differences among the different mediterranean basins but that they are strongly related to regional hydrographic patterns hydrography controls the seasonality and depth of the turbulent mixing which differ between the western and the eastern basins the depth of the mixed layer and its seasonal stratification and the strength of the pycnocline nutrient supply and primary production are mostly regulated by these dynamics one may therefore expect that the species assemblages on the sea floor and in deep sea cores will also correlate to the various hydrographic parameters of the overlying water masses

the surface circulation of the balearic sea until recently the surface circulation of the balearic sea has been viewed as largely cyclonic with a fairly quiescent central dome however recent studies involving ship data tracked drifters current meter moorings and satellite imagery indicate that this sea has strong mesoscale variability and a more complex general circulation these studies together with an examination of registered satellite imagery collected during the western mediterranean circulation experiment wmce indicate that the surface circulation is strong year round and characterized by two permanent density fronts located on the continental shelf slope the catalan front and the balearic islands shelf slope the balearic front the catalan front is the more active of the two fronts in the northern area a plume of cold water is frequently observed moving southward along the continental slope region shedding dipole eddies along the leading edge of the plume in addition the catalan front continuously spawns energetic filaments that appear to be associated with the plume of cool water the likely mechanism of formation of these filaments is the deflection of the cold water by the regional submarine canyons

characterization of cavities using the gpr lidar and gnss techniques the study of the many types of natural and manmade cavities in different parts of the world is important to the fields of geology geophysics engineering architectures agriculture heritages and landscape ground penetrating radar gpr is a noninvasive geodetection and geolocation technique suitable for accurately determining buried structures this technique requires knowing the propagation velocity of electromagnetic waves em velocity in the medium we propose a method for calibrating the em velocity using the integration of laser imaging detection and ranging lidar and gpr techniques using the global navigation satellite system gnss as support for geolocation once the em velocity is known and the gpr profiles have been properly processed and migrated they will also show the hidden cavities and the old hidden structures from the cellar in this article we present a complete study of the joint use of the gpr lidar and gnss techniques in the characterization of cavities we apply this methodology to study underground cavities in a group of wine cellars located in atauta soria spain the results serve to identify construction elements that form the cavity and group of cavities or cellars the described methodology could be applied to other shallow underground structures with surface connection where lidar and gpr profiles could be joined as for example in archaeological cavities sewerage systems drainpipes etc

paleoenvironmental changes at the lower pleistocene montalbano jonico section southern italy global versus regional signals abstract integrated high resolution data from calcareous plankton assemblages foraminifera and nannofossils together with geochemical and mineralogical investigations have been collected at the on land montalbano jonico section southern italy in order to reconstruct the paleoenvironmental changes through marine isotope stages mis 23 37 time series analysis on globigerina bulloides and cassidulina carinata 18o records and on selected calcareous plankton proxies mainly revealed the occurrence of precession and obliquity forcing the deposition of sapropel layers which are interbedded in the montalbano jonico section was driven by water column stratification insolation cycle i 104 and enhanced sea surface water productivity insolation cycle i 112 i 102 and i 86 different paleoenvironmental conditions mark the sedimentary evolution of the section from 1240 to 1082 ka mis 37 mis 32 high percentage abundances of warm and oligotrophic planktonic foraminifera and calcareous nannofossil taxa indicate the establishment of oligotrophic and stratified surface water conditions a key paleoenvironmental change occurred during mis 31 from about 1080 to 1065 ka which was a very warm interglacial characterized by an increase of tropical subtropical globigerinoides ruber group and globigerinoides trilobus and low salinity braarudosphaera bigelowii sea surface water taxa during this interval more humid climate conditions coupled with changes in local paleomorphology may have triggered a higher and unusual freshwater input and the creation of a new entry point for sediment supply into the basin from a different drainage area from about 1065 to 1010 ka mis 30 mis 29 a cool and dry climate prevailed in the circum mediterranean area during a time of precession maxima this favored lowered sea surface temperatures and an increase of polar water neogloboquadrina pachyderma left coiling there are also indications of a reduction of the terrigenous input from the new source area from 1010 ka upward mis 28 mis 23 the higher abundances of globigerina bulloides turborotalita quinqueloba and calciosolenia spp indicate enhanced productivity conditions probably related to high turbidity of sea surface waters triggered by a more conspicuous sediment input from land analysis of the long term trends in the multiproxy patterns suggests that the major paleoenvironmental changes occurred as a consequence of the combined effect of orbitally controlled global climate and regional processes

organic rich layers in the metochia section gavdos greece evidence for a single mechanism of sapropel formation during the past 10 my abstract three well developed 10 ma old sapropels from the island of gavdos greece were selected for a detailed geochemical micropaleontological and sedimentological study the sapropels are characterized by a high organic carbon and a low carbonate content productivity was higher during sapropel formation as indicated by increased ba contents and higher percentages of the planktonic foraminiferal species neogloboquadrina acostaensis enrichment of mo and v in the sapropels indicates less oxygenated bottom water conditions which is supported by the flourishing of low oxygen tolerant benthic foraminifera variation in grainsize and the ti al ratio point to an alternating dominance of fluvial sapropels and eolian derived homogeneous intervals terrigenous clastics evidence for a local origin of the enhanced fluvial input comes from the gradual replacement of the sapropels by cyclic turbidite sequences which were fed by bed load type rivers the increased fluvial input during sapropel formation increased the sedimentation rate and caused the observed carbonate depletion the results obtained for the gavdos sapropels are consistent with those of previous studies of younger sapropels and related caco 3 cycles in the mediterranean the consistency in most of the geochemical and micropaleontological characteristics indicates that all sapropels and related layers are the result of a single mechanism for at least the past 10 my namely precession induced dry wet oscillations in the mediterranean climate still the effect of this mechanism on the intensity of surface water productivity dilution and diagenetic signals may differ from site to site depending on location depositional environment and intensity of the astronomical forcing

speleothem u th age constraints for the last glacial conditions in the apuan alps northwestern italy abstract during the quaternary several glaciations occurred in the mountain regions around the mediterranean and in recent years new ages have better constrained their timing however this is not the case for the apuan alps a high rainfall mountain chain adjacent to the mediterranean sea here in spite of the widespread evidence for glaciers the complete lack of geochronological information hinders our understanding of glaciation history in this paper we utilize speleothem ages to better constrain the timing of these glacial features we re examine 293 uranium thorium ages from 19 speleothems collected in five caves at different elevations after a period of very low growth between 160 and 132 ka the analysed speleothems grew almost continuously to 75 ka this period was followed by intermittent growth with lower deposition rate and presence of hiatuses until 12 5 12 ka this is consistent with an ice coverage persisting over the apuan alps inhibiting or interrupting the growth of speleothems via the limited availability of groundwater and the scarcity absence of soils this interval is much greater than the time interval that has previously been attributed to the existence of glaciers on the apuan alps which has been assumed to be restricted to marine isotope stage mis 2 instead ice cover probably also appeared in the apuan alps during mis 4 the phase of restarting of growth which may implies the definitive or substantial glacier melts seem to predate the holocene

incidence of obliquity and precession forced milankovitch cycles in the western mediterranean early messinian sedimentation in the sorbas basin almeria southern spain spectral analysis of the messinian abad marls in the cariatiz section sorbas basin south eastern spain reveals three relevant orders of cyclicity the most significant cycle is in the lowest frequency average thickness of 365 cm 4 5 cycles in the section it is recorded in the composition of planktic foraminiferal assemblages indicative of surface water temperature planktic and benthic stable isotope signals and carbonate proportions the planktic assemblages isotope values and carbonate proportions also record a middle frequency cycle with an average of 177 cm 9 10 cycles in the section the highest frequency cycle average of 132 cm 12 13 cycles in the section is mainly reflected in siliciclastic and calcite proportions age constraints and cycle patterns suggest that the lowest frequency cycle was forced by orbital obliquity whereas the two higher frequency ones are related to precession obliquity seems to have controlled major changes in surface water temperature in the sorbas basin during the early messinian surface water temperature was also affected by precession with changes in weathering and run off spectral analysis has also been applied to vertical shifts of reef facies throughout the progradation of the cariatiz reef this reef is coeval with the cariatiz section vertical shifts of reef talus breccias point to the existence of 4 5 major cycles of sea level change whereas 7 9 higher frequency cycles are reflected in the repeated occurrence of lowstand non reefal deposits correlation with the cycles observed at the cariatiz section suggests that obliquity forced glacio eustatic sea level oscillations in the western mediterranean during the late miocene

sedimentary stable isotope and micropaleontological records of paleoceanographic change in the messinian tripoli formation sicily italy abstract the tripoli formation 6 96 5 98 ma of the central sicilian basin provides a good record of the paleoceanographical changes that affected the mediterranean during the transition from slightly restricted conditions to the onset of the messinian salinity crisis the falconara gibliscemi section has been selected for an integrated approach at a high resolution scale using sedimentology stable isotopes of the carbonates and microfossils the sedimentary succession includes 46 precession controlled cycles resulting from the periodical increase in biosiliceous productivity diatomites that followed the deposition of marls and pinkish laminites which appear as sapropel type deposits induced by the oceanic fertilization by terrestrial nutrients during wet periods higher scale environmental changes are superimposed to this precession forced rhythmicity there is a general trend of increasing basin restriction from near marine conditions at the base of the tripoli to semi closed settings in its uppermost part which are the prelude of the salinity crisis this pattern reflects the hydrological response of the mediterranean to the progressive decrease of the atlantic inputs and an enhanced influence of the climate on depositional conditions however this evolution is not linear and shows successive phases of different duration during the first period until 6 71 ma open atlantic mediterranean exchanges maintained relatively stable marine conditions the second period 6 71 6 29 ma marks an important step in the basin restriction with a wider range of salinity fluctuations and an increased bottom stagnation the 6 71 ma event which is correlated at a mediterranean scale may have resulted from shallowing of the mediterranean gateway under a tectonic control this shallowing reduced the oceanic inputs resulting in an increased climatic constraint of the mediterranean hydrology during the third period 6 29 6 03 ma an increase of the surface water salinity resulted in stressful conditions for the marine microfauna the 6 29 ma change is a major step in the restriction that may be correlated with the intensification of the glaciation recorded in the atlantic which could have enhanced the effects of the tectonic closure the last two cycles 48 and 49 that underlie the calcare di base witnessed the rapid transition to a semi closed mediterranean setting characterized by large variations of salinity from diluted to hypersaline conditions under a dominant climatic control and by the nearly complete disappearance of the marine organisms long trend environmental changes recognized within the tripoli formation resulted from a complex set of interfering factors controlling the water fluxes exchanged between the mediterranean and the world ocean most of the rapid changes identified in falconara gibliscemi at 7 16 6 71 and 6 29 ma that occurred simultaneously in the western and eastern mediterranean were mainly controlled by the stepwise tectonic closure of the atlantic connections although a glacio eustatic overprint cannot be completely excluded

delta growth and river valleys the influence of climate and sea level changes on the south adriatic shelf mediterranean sea abstract incised valleys across continental margins represent the response of fluvial systems to changes in their equilibrium dynamics mainly driven by base level fall forced by glacial eustatic cycles the manfredonia incised valley formed during the last glacial sea level lowstand when most of the southern adriatic shelf was sub aerially exposed but the outer shelf remained under water the pronounced upstream deepening of the valley is ascribed to river incision of the mis5e highstand coastal prism and related subaqueous clinoform under the influence of mis5 4 sea level fluctuations while the downstream shallowing and narrowing mainly reflects the impact of increased rates of sea level fall at the mis3 2 transition on a flatter mid outer shelf until 15 ka bp the valley fed an asymmetric delta confined to the mid outer shelf testifying that continental and deep marine systems remained disconnected during the lowstand sea level rise reached the inner shelf during the early holocene drowning the valley and leading to the formation of a sheltered embayment confined toward the land at this time part of the incision remained underfilled with a marked bathymetric expression this mini basin was rapidly filled by sandy bayhead deltas prograding from both the northern and southern sides of the valley in this environment protected by marine reworking and where sediment dispersal was less effective the accommodation space was reduced and autogenic processes forced the formation of multiple and coalescing delta lobes bayhead delta progradations occurred in few centuries between 8 and 7 2 ka cal bp confirming the recent hypothesis that in this area the valley was filled during the formation of sapropel s1 this proximal valley fill representing the very shallow water equivalent of the cm thick sapropel layers accumulated offshore in the deeper southern adriatic basin is of key importance in following the signature of the sapropel in a facies tract ideally from the shoreline to the abyss

seasonal changes in species composition numbers mass size and isotopic composition of planktonic foraminifera settling into the deep sargasso sea abstract planktonic foraminifera recovered from six successive sediment trap samples collected over fourteen months at a depth of 3200 m near bermuda show varied responses to seasonal changes in the near surface hydrography these include changes in species composition and within species changes in number of individuals collected per unit time average size and weight of individuals and in oxygen and carbon isotopic composition a total of seventeen species were identified and eleven were sufficiently abundant for isotopic analysis in at least some of the samples the accumulations on the sea floor of some of these species can be expected to contain a strong seasonal component in their oxygen isotopic composition which may be utilized in paleoclimatic and paleo oceanographic reconstructions best suited to this purpose are those species which form their tests in isotopic equilibrium with surface water and whose abundance is confined to a portion of the year only the best examples are pulleniatina o bliguiloculata globigerinoides conglobatus and neogloboquadrina dutertrei globigerinoides ruber is a good estimator of the average surface water temperature because it occurs in rather even abundance throughout the year hastigerina pelagica though very abundant in surface water is practically eliminated even before arrival on the sea floor by partial resorption and structural weakening of the tests during gametogenesis orbulina universa globorotalia truncaltulinoides and globorotalia hirsuta show morphological and istopic evidence for contibnued calcification in deeper water after initial test formation near ther surface globigerina bulloides represents the most striking example of oxygen isotopic disequilibrium with sea water

surface and deep water variability in the western mediterranean odp site 975 during insolation cycle 74 high resolution calcareous plankton and molecular biomarker signals abstract we reconstructed changes in productivity and surface subsurface and deep water dynamics in the western mediterranean through a multi proxy study of ocean drilling program site 975 between late marine isotope stage mis 20 and early interglacial mis 19 our high resolution study down to 200 year resolution combines calcareous plankton assemblages coccolithophores and foraminifera biomarkers c37 alkenones n alkanes n alcohols and elemental proxies total organic carbon total nitrogen calcium carbonate surface water conditions are derived i from high resolution 18o and 13c records obtained from the planktonic foraminifer globigerina bulloides and ii from summer and winter foraminifera based sea surface temperature reconstructions sstjas foram sstjfm foram achieved through transfer function the integration of the whole dataset makes it possible to identify in the balearic sea and to accurately characterize for the first time an organic rich layer orl during latest mis 20 early mis 19 close to i cycle 74 its presence is marked firstly by higher values of total nitrogen tn and an increase of total c37 alkenone and total organic carbon toc preserved in the sediments the multi proxy approach reveals that the deglacial phase played a prominent role for orl formation that was characterized by centennial scale phases the alcohol preservation index api suggests that the shoaling of the circulation which boosted marine productivity started in the deglaciation and in combination with freshening by atlantic water inflow riverine input and surface water buoyancy during sea level rising culminated during the orl event at this time calcareous plankton proliferated on subsurface surface waters benefiting from ameliorating conditions which promoted maximum marine productivity and higher organic matter preservation on the seafloor

marine and terrestrial climate variability in the western mediterranean sea during marine isotope stages 20 and 19 abstract the climate variability within late marine isotope stage mis 20 and mis 19 is examined with particular reference to the response of marine and terrestrial realms in the area surrounding the alboran sea western mediterranean sea sediment samples from the ocean drilling program site 976 were used to derive high temporal resolution average resolution of 450 years palynological pollen and spores and calcareous plankton coccolithophores and foraminifera records these data together with the new 18og bulloides make it possible to discuss the paleoenvironmental changes within a well constrained chronological frame cooler phases including late mis 20 and several cold spells during mis 19b a are marked on land by the expansion of open vegetation formations dominated by steppe and semi desert taxa at the same time the western mediterranean sea is marked by the incursion of north atlantic polar water planktonic taxa mis 19c and interstadials of mis 19b a are characterized by the spread of prevalent temperate forest taxa that parallel the expansion of warm water calcareous plankton taxa during periods of lighter 18o climate variations at both precessional and millennial to sub millennial time scales expressed by on land and marine signals highlight the sensitivity of the western mediterranean area to both orbital forcing and rapid internal oscillations of the climate systems involving remote connections with north hemisphere high latitudes the correlation within the central western mediterranean and north atlantic climate dynamics including the time spatial gradients related to regional and global climate processes contributes to the reconstruction of the earth climate dynamics and marine vs land responses in full early middle pleistocene transition these new evidences also provide an opportunity to improve knowledge of mis 19c now considered due to its orbital geometry the best orbital analogue to the holocene

global climate instability reflected by eastern mediterranean marine records during the late holocene abstract extremely high sediment accumulation rates in the southeastern se mediterranean off israel make this region ideal for high resolution paleoceanographic reconstructions two cores were examined and foraminiferal oxygen and carbon isotope composition as well as physical and geochemical properties of the sediments were used to reconstruct the climatic and environmental changes of the se mediterranean basin during the late holocene 3 6 ka the 18o values of globigerinoides ruber suggest that the freshwater balance changed several times during this time interval humid phases took place between 3 5 3 0 ka bp and 1 7 1 0 ka bp the later was accompanied by enhanced preservation of terrestrial organic matter within the sediment ors event relatively more arid conditions prevailed in this area between 3 0 and 1 7 ka bp during the last millennia at ca 0 8 and 0 27 ka two climatic events occurred which are probably correlative to both the medieval warm period and the cooling global event known as the little ice age respectively a long term slight increase in planktonic foraminiferal 18o values occurs together with a gradual decrease in the 13c values of both g ruber and the benthic foraminifera uvigerina mediterranea this trend is associated with an increase in sedimentation rates ti al ratio magnetic susceptibility and color index of the sediments we suggest that this trend shown by various independent proxies seems to be related to the aridification process that started ca 7 0 ka in the mid low latitude desert belt and the se mediterranean region and continuous until the present the long term 13c decrease shown by surface and bottom water foraminifera reflects a gradual change in the 13c of the dissolved co2 of the entire se mediterranean water column this follows the global co2 rise in the late holocene as a result of the terrestrial biomass destruction during the aridification process moreover the gradual reduction of the vegetation cover in east africa led to an increased erratic flood related sediment flux via the nile river up to the present this is reflected by the general change in the local sediment composition at 3 6 ka the saharan eolian input reached 65 whereas at about 0 3 ka 70 of the se mediterranean sediment was composed of nile particulate matter

foraminiferal ecozones a high resolution proxy for the late quaternary biochronology in the central mediterranean sea the planktic foraminiferal distribution identified in 60 cores collected in different basins of the mediterranean sea allowed to establish an ecostratigraphical scheme which provides a very important tool for the biochronological subdivision of the uppermost quaternary we identified a succession of ten ecozones during the last 23 ka in the tyrrhenian basin and eight ecozones in the adriatic sea during the last 15 ka the ecozones boundaries have been calibrated by 14c ams radiometric data and by the stable oxygen isotope record the chronological framework defined by the successive bioevents shows a very high resolution millenary scale and evidences that the changes in the planktic microfauna occurred more or less synchronously throughout the central mediterranean sea differences due to different oceanographic settings of the basins do not affect the general distributional pattern of planktic foraminifera

seasonal variability in the δ18o and δ13c of planktonic foraminifera from an upwelling environment sediment trap results from the san pedro basin southern california bight stable isotopic analyses 18o and 13crpar on four species of planktonic foraminifera collected from high resolution time series sediment trap sampling indicate that rapid and significant seasonal variability occurred in response to rapid changes in both the hydrographic environment and the isotopic composition of ambient seawater specimens were collected at a depth of 500 m for 28 consecutive 1 week periods in the san pedro basin within the southern california bight a region seasonally influenced by upwelling hydrographic monitoring of the study area revealed a 6 week period late april to mid june during which pulses of upwelling occurred causing significant increases in the oxygen isotopic composition of surrounding waters while decreasing the carbon isotopic composition analyses of globigerina bulloides orbulina universa neogloboquadrina dutertrei and neogloboquadrina pachyderma right coiling indicate that during the upwelling period these species live respectively at the surface in the surface mixed layer within the thermocline and below the thermocline globigerina bulloides ascends from well below the thermocline to the surface at the onset of upwelling and increases production to its maximum simultaneously as its morphology changes to less calcified open forms both n dutertrei and n pachyderma follow isothermal ranges migrating to shallower waters during upwelling and subsequently descending after upwelling ceases neogloboquadrina dutertrei appears to inhabit the region associated with both the thermocline base and chlorophyll maximum when it is most abundant following upwelling orbulina universa increases its depth habitat as solar irradiance increases but this species decreases in abundance during upwelling the 18o signal of o universa appears to be a useful indicator of seasonal temperature variations above the thermocline whereas the 18o of g bulloides documents near surface temperatures during upwelling the 13c signal of both n dutertrei and n pachyderma appears to record the 13c of equilibrium calcite for the regions of the thermocline and just below the thermocline respectively due to the relative preservation potentials of the four species analyzed only n dutertrei and n pachyderma are likely to be preserved in the sedimentary record in regions of oxygenated bottom waters thus an actual record of hydrographic conditions during upwelling as would be found in tests of g bulloides is not preserved instead conditions before n pachyderma and just after n dutertrei are more likely recorded

orbital variations in planktonic foraminifera assemblages from the ionian sea during the middle pleistocene transition abstract the middle pleistocene transition 1 2 0 7 ma is the most recent re organization of the global climate system which includes variations in the frequency and amplitude of glacial interglacial cycles increased ice sheet volume sea surface temperature cooling and a significant drop in the co 2 atmospheric levels here we present high resolution planktonic foraminifera data mean sampling resolution of about 780 years from core lc10 recovered in the ionian sea eastern mediterranean between 1 2 and 0 9 ma selected taxa among them g ruber t quinqueloba and g bulloides show significant periodicities that can be associated to orbital cycles mainly precession and obliquity the planktonic foraminifera based paleoclimatic curve exhibits a cooling linear trend that can be associated to similar phenomena observed in the north atlantic on the other hand we refer to the influence of the north african monsoon the occurrence of two peaks of the low salinity tolerant species g quadrilobatus that fall in coincidence of sapropel layers finally we discuss the distribution pattern of n pachyderma sinistral coiling with peaks up to about 20 between mis 30 and 28 and compare it to middle late quaternary records of the sicily channel and western mediterranean

messinian productivity changes in the northeastern atlantic and their relationship to the closure of the atlantic mediterranean gateway implications for neogene palaeoclimate and palaeoceanography the stable isotope composition of planktic and benthic foraminifera and the distribution of selected benthic foraminiferal species from a messinian record of the lower guadalquivir basin northeastern atlantic ocean show that regional productivity changes were linked to glacioeustatic fluctuations glacial periods were characterized by poorly ventilated bottom waters as a result of weak atlantic meridional overturning circulation amoc and by phases of high productivity related to intensified upwelling in contrast well ventilated bottom waters owing to strong amoc the presence of degraded organic matter in the upper slope and high input of degraded terrestrial organic matter derived from fluvial discharge to the outer shelf were recorded during interglacial periods before closure of the adjacent guadalhorce corridor at 6 18 ma which was the final active betic atlantic mediterranean gateway the study area was alternately influenced by well ventilated mediterranean outflow water mow and poorly ventilated atlantic upwelled water auw following closure of the corridor cessation of the mow reduced the amoc and promoted glacial conditions in the northern hemisphere resulting in the establishment of local upwelling cells

the oxygen and carbon isotope distribution in the mediterranean water masses abstract the oxygen and carbon stable isotope compositions of the present day mediterranean waters have been measured in order to evaluate their variability which is related to the specific climatic and hydrological conditions within the basin the experimental equation between the 18 o value and the salinity of water based on 300 measurements on surface intermediate and deep waters sampled during the vicomed 2 and 3 cruises in the western central and eastern mediterranean has a slope of 0 27 a value which is significantly lower than the slope of 0 45 as defined in the northeast atlantic ocean this difference in the 18 o salinity relationship which occurs immediately in the alboran basin is basically a characteristic of the climatic regime of the mediterranean i e of an excess evaporation over fresh water input the largest variations of these two parameters 18 o of water and 13 c of co 2 are observed in the surface waters mostly in the western mediterranean this evolution mirrors the progressive eastward restriction which separates the less evaporated and more productive western basins from the more evaporated and less productive eastern basins the intermediate waters constitute a homogeneous layer however their 18 o values decrease eastward by 0 35 at maximum due to progressive dilution by mixing with overlying and underlying water masses their 13 c values decrease also eastward by 0 35 at maximum due to an increasing input of nutrients issued from the regeneration of sinking organic particles the deep waters have similar 18 o values but slightly higher 13 c values often by less than 0 1 than the overlying intermediate waters indicating generally well ventilated conditions due to active winter convection

abrupt cold spells in the northwest mediterranean hitherto unknown abundance peaks of left coiling l c neogloboquadrina pachyderma from a gulf of lions piston core indicate that abrupt cold spells associated with atlantic heinrich events affected the mediterranean n pachyderma l c is typical of sub polar waters in the open ocean the southern edge of its glacial north atlantic bioprovince reached south portugal only trace abundances of n pachyderma l c are known from quaternary mediterranean sediments suggesting that no significant invasions occured via the strait of gibraltar the gulf of lions abundance peaks therefore seem to reflect area specific thriving of a normally rare but indigenous taxon in the western mediterranean through local favorable habitat development the general planktonic foraminiferal record suggests that the basic hydrographic regime in the gulf of lions with wintertime deep convective overturn was relatively stable over the past 60 kyr under these conditions high abundances of n pachyderma l c would essentially imply temperature reductions of the order of 5 8 relative to the present

further constraints on the diagenetic influences and salinity effect on globigerinoides ruber white mg ca thermometry implications in the mediterranean sea we analyzed mg ca ratios of the planktonic species globigerinoides ruber white picked from 49 box core samples covering the whole mediterranean sea and 2 core tops from the atlantic ocean over the entire data set we found no significant correlation between mg ca and 18o derived calcification temperatures this lack of correlation is chiefly due to the presence of an early diagenetic mg rich calcite coating which can constitute up to 20 of the total shell calcite in the central and eastern mediterranean basin and result in anomalously high mg ca values and a high scattering in the western mediterranean sea however g ruber mg ca scattering shows smaller amplitude and mg rich calcite remains under the xrd detection limit sem observations indicate that only a few samples are affected by trace amounts of post mortem calcite overgrowths most of this calcite being likely removed during the chemical cleaning for mg ca analyses using core top sediments from the western mediterranean sea we performed an empirical calibration exercise which confirms that g ruber mg ca is not only related to temperature but it is also significantly affected by sea surface salinity this salinity effect is not specific to high salinity environments such as the mediterranean sea since it appears to be coherent with recent results obtained on indo pacific and atlantic surface sediments which suggest that a 1 psu change in sss results in a 1 7 c mg ca temperature bias this sensitivity to salinity is significantly higher than those deduced from culture experiments

western versus eastern mediterranean paleoceanographic response to astronomical forcing a high resolution microplankton study of precession controlled sedimentary cycles during the messinian abstract planktic foraminifera and stable isotopes were analyzed in samples from four precession controlled sedimentary cycles from southeastern spain and the island of gavdos greece to reconstruct the paleobiologic and paleoceanographic response of the western and eastern mediterranean to astronomically driven climate variability during the messinian although the lithological succession in the western mediterranean cycles sapropel homogeneous marl diatomite homogeneous marl is different from that in the eastern mediterranean sapropel diatomite homogeneous marl the pelagic biological succession is similar four stages were recognized in both environments characterized by the dominance of warm oligotrophic foraminifera stage 1 neogloboquadrinids and globorotaliids stage 2 globigerina bulloides stage 3 and globigerinita glutinata stage 4 the first stage occurs during deposition of the upper part of the sapropels in spain and the sapropels and part of the diatomites on gavdos this stage is inferred to relate to high summer insolation and strong surface water stratification with winter temperatures not high enough to allow eutrophic foraminifera growth stage 2 occurs during the deposition of the lower homogeneous marls in spain and the middle upper part of the diatomites in greece most likely indicating stratification with colder winter temperatures and a nutricline above the euphotic layer the end of surface water stratification is indicated during stage 3 by the replacement of the neogloboquadrinids by g bulloides which occurs at the base of the diatomites in spain and near the top of the diatomites in greece we link this event to the appearance of dryer climates in the mediterranean at times of relatively low summer insolation in the northern hemisphere which would result in higher surface salinities deep water convection and deep water ventilation stage 4 defined by the dominance of g glutinata and low concentrations of planktic foraminifera appears linked to the base of the sapropels both in the western and eastern mediterranean the onset of sapropel deposition occurred at a time of relatively high surface water salinities as suggested by the heavy 18o in orbulina universa and prior to the development of surface water stratification evident in the subsequent increase in warm oligotrophic foraminifera gavdos diatomites were deposited under anoxic conditions whereas sorbas diatomites were formed in an oxygenated environment the difference between western and eastern mediterranean diatomites would be due to differences in hydrographic conditions between the two studied settings

field based validation of a diagenetic effect on g ruber mg ca paleothermometry core top results from the aegean sea eastern mediterranean recent work across the mediterranean sea has illustrated the salinity and overgrowth effects on planktonic foraminiferal mg ca which potentially confound the use of this as a temperature proxy for paleoceanographic reconstructions to test and verify these effects we present new aegean sea results which reveal mg ca values that were unreasonably high to be explained by temperature or salinity variations alone confirming that foraminiferal mg ca is affected by diagenesis we have specifically targeted globigerinoides ruber w sensu stricto from a series of modern core tops spanning a strong sea surface salinity gradient and a minor sea surface temperature range along a north south aegean sea transect scanning electron microscopy analyses show that g ruber specimens were covered by microscale euhedral crystallites of inorganic precipitates this secondary calcite phase seems to be responsible for the anomalously high mg ca ratios and likely formed near the sediment water interface from caco3 supersaturated interstitial seawater we also have clear evidence of diagenetic alteration in a north south direction along the aegean sea possibly depending on salinity and calcite saturation state gradients these observations illustrate the necessity of alternative techniques e g flow through time resolved analysis or laser ablation inductively coupled plasma mass spectrometry to potentially overcome these diagenetic issues and develop a more reliable and sensitive temperature proxy in similar subtropical settings characterized by high salinity excessive evaporation and restricted circulation

circulation changes and nutrient concentrations in the late quaternary aegean sea a nonsteady state concept for sapropel formation sapropel forming conditions we identify the start of seasonal stratification and highlight a lag in d 18 o response of the planktonic foraminifer n pachyderma to termination t1b as identified in the d 18 o record of g ruber by use of a simple model we determine that this offset cannot be a function of bioturbation effects the lag is of the order of 1 kyr and suggests that isolation of intermediate deep water preceded the start of sapropel formation by up to 1 5 kyr using this discovery we propose an explanation for the major unresolved problem in sapropel studies namely the source of nutrient supply required for export productivity to reach levels needed for sustained sapropel deposition we suggest that nutrients had been accumulating in astagnant basin for 1 1 5 kyr and that these accumulated resources wereutilized duringthe deposition of s1 in addition we provide a first quantitative estimate of the diffusive 1 e mixing timescale for the eastern mediterranean in its stratified sapropel mode which is of the order of 450 years index terms 1050 geochemistry marine geochemistry 4835 4850 3030 marine geology and geophysics micropaleontology 3339 meteorology and atmospheric dynamics ocean atmosphere interactions 0312 4504 4267 oceanography general paleoceanography 4870 oceanography biological and chemical stable isotopes keywords sapropel mediterranean holocene foraminifera climate variability

vertical distribution and isotopic fractionation of living planktonic foraminifera from the panama basin a model1 2 which explains the vertical and seasonal distribution of planktonic foraminifera was developed using data from the western north atlantic and is comprised of three tenets 1 the conditions in the photic zone upper 80 100 m exclusively dictate planktonic foraminifera species composition and abundance throughout the water column 2 species are vertically stratified within the photic zone according to their temperature preference depth distribution according to temperature preference has been proposed by several authors3 based on isotope analyses of sediments due to seasonal temperature variations seasonal variations in the 18o composition of seawater and species specific isotope fractionation rigorous proof of this hypothesis cannot be provided from sediment analyses alone 3 the chlorophyll maximum is a major food source zone which is preferentially exploited by foraminifera our data from the panama basin which are presented here are confirmation of this model the panama basin in the eastern equatorial pacific which has a shallow and steep thermocline was sampled for living planktonic foraminifera a multiple opening closing net and environmental sensing system mocness 4 was used to collect 13 sets of eight vertically stratified oblique samples we report here the quantitative distribution and stable isotopic composition of planktonic foraminifera from four mocness tows taken over 5 days during august 1979 rv knorr cruise 73 at 5 20 n 8 50 w each tow consisted of eight samples which integrated 12 5 m intervals from 0 to 100 m for moc 126 25 m intervals from 0 to 200 m for moc 127 100 150 m intervals from 0 to 1 000 m on moc 128 and 250 m intervals from 0 to 2 000 m on moc 131

impact of climate and sea level changes on the ventilation of intermediate water and benthic foraminifer assemblages in the gulf of lions off south france during mis 6 and 7 abstract benthic and planktic foraminifer assemblages together with oxygen stable isotope were studied in the prgl1 borehole promess1 drilled on the upper slope of the gulf of lions with a view to reconstruct the impact of climate changes on surface and bottom waters between mis7 and mis6 foraminifer species were grouped by r mode principal components analysis we obtained 3 factors in benthic assemblages that were related to eutrophic mesotrophic and oxygenated environments in the planktic foraminifer assemblages four factors were considered that explained the changes of sea surface temperature productivity and turbulence in the water column variations in the terrestrial organic carbon supply associated with eustatic sea level changes mainly controlled oxygen consumption and the benthic communities during mis7 the benthic communities were mainly mesotrophic owing to the low supply of terrestrial organic carbon because the coastline was distant from the slope however during mis6 the sea level drop caused a rapid progradation of the river rhone prodelta and dramatically increased the supply of terrestrial organic carbon resulting in a pronounced increase in eutrophic foraminifers apart from the effect of the river discharge which contributed to the reduced oxygen content we recognized periods of intense bottom ventilation during mis 6 and to a lesser extent in the substadial stages of mis 7 the ventilation events are well matched by higher turbulence and convection in the water column during cold episodes associated with an intensification of the northwesterlies in contrast during the short millennial scale warming events of mis6 the stratification of the water column rapidly reduced bottom ventilation these results are consistent with those reported in previous studies that point to enhanced dense water formation in the gulf of lions during cold stages

the western mediterranean during the last glacial attacking a no analog problem abstract assemblages of planktic foraminifera from the western mediterranean during the last world ice volume maximum 18 000 yrs b p are presented for two rapid sedimentation rate deep sea cores one from the northern and one from the western part of the basin the locations permit monitoring of hydrography in the alboran sea where exchange occurs with the atlantic and in the northern balearic sea where the warm mediterranean out flow to the world ocean is generated by a unique vertical mixing process this latter makes a significant contribution to the heat budget of the global deep sea thus the assemblages reflect western mediterranean oceanography and interaction with the atlantic during the last ice age quantitative empirical paleo oceanographic interpretation of the faunas is not possible because they occur in relative abundances not seen in the north atlantic or mediterranean of today however some more general deductions of paleohydrography are possible the faunas indicate that the western mediterranean was considerably colder 18 000 yrs b p and highly seasonal large annual thermal contrast reflecting the seas nearly land locked position climate surrounding the basin appears to have been quite variable over periods of less than 500 years the faunas also indicate that interchange between the eastern and western mediterranean seas was much altered during the glacial and that the character of the water returned to the atlantic from the mediterranean was quite different probably colder from that of the present the deep world ocean would then have been lacking a significant heat source 18 000 yrs b p

are productivity and stratification important to sapropel deposition microfossil evidence from late pliocene insolation cycle 180 at vrica calabria we present the results of a micropaleontological study performed on the sapropel sequence associated with insolation cycle 180 from the plio pleistocene vrica sequence calabria italy we performed a high resolution study on the 3 38 m thick layer c from a core drilled close to the classical outcrop section in which we analyze fluctuations in the abundance and composition of calcareous nannofossils and planktic and benthic foraminifera changes in the fossil assemblages reveal at least three major paleoenvironmental phases in layer c the base of the sapropel contains an abrupt decrease in benthic fauna that continues through all of layer c it also has an increase of the coccolithophorids species coccolithus pelagicus planktic foraminifera show at the same depth a peak of the cold species globorotalia scitula these changes are followed by decreases in the carbonate preservation index and in abundances of globigerinita glutinata globigerinita uvula and neogloboquadrina pachyderma sinistral which suggest cold and highly productive upwelling waters a short interval in the middle of the sapropel is characterized by low values of c pelagicus a fluctuating increase of pseudoemiliania lacunosa and among the foraminifera an increase of globigerinoides ruber together with the presence although decreased of g glutinata g uvula and n pachyderma sinistral we interpret these features as suggesting high seasonality with warm stratified and probably oligotrophic waters during summer and relatively cold conditions during winter finally the topmost interval of the vrica layer c exhibits the re appearance of p lacunosa together with abundant siliceous phytoplankton planktic microfauna show the disappearance of the cold species g glutinata g uvula and n pachyderma sinistral thus this interval appears to be characterized by warmer temperature the transition from the laminated to the massive sediment displays a sequence of events including a decrease of the carbonate preservation index and peaks of globorotalia inflata and g scitula suggesting again upwelling and mixing of the whole water column and thus transition to the oxygenated conditions characterizing the massive layer neither increased productivity nor stratification appear to characterize the whole sapropel interval which is however always dysoxic

calcareous dinoflagellate cysts in surface sediments from the mediterranean sea distribution patterns and influence of main environmental gradients abstract the distribution of calcareous dinoflagellate cysts in surface sediments from the mediterranean sea was quantitatively analysed the samples contain 11 cyst species and the vegetative coccoid thoracosphaera heimii cyst abundance increases towards the deeper parts of the basins and is generally higher in the eastern mediterranean sea three major distribution characteristics exist 1 different assemblages in oceanic and neritic regions 2 little agreement with the associations of areas studied so far like the atlantic ocean and 3 a unique oceanic assemblage in the eastern mediterranean sea a gradual change in cyst assemblages from the western to the eastern mediterranean sea was observed and statistically compared with the main environmental gradients in the upper water column temperature nitrate concentration and possibly salinity appear to be the most important factors controlling cyst production three groups containing cysts with similar environmental preferences can be distinguished 1 an eastern mediterranean group related to relatively high temperature and salinity but low nitrate concentration 2 a group of more or less consistently abundant cosmopolitan species tolerating or even preferring relatively low temperature and salinity but high nitrate concentration and 3 a group containing species that are possibly adapted to neritic environments and have probably been transported from coastal areas into the studied regions in contrast to other calcareous plankton calcareous dinoflagellate cysts correlate strongly with the main environmental gradients in the mediterranean sea bearing a high potential for palaeoenvironmental reconstructions

integral view of holocene precipitation and vegetation changes in the nile catchment area as inferred from its delta sediments we compare geochemical and pollen data of several well dated high resolution cores to provide an integral holocene overview of nile outflow sedimentation and vegetation in and around the nile delta we show that the focus point of the nile plume varied considerably as indicated by planktonic foraminifer globigerinoides ruber oxygen isotopes tracing nile discharge differences in an east west delta transect at 13 11 5 cal kyr bp nile discharge was low and runoff was predominantly directed to the western part of the delta sediment arriving in the delta during that period was dominated by ethiopian highland similar to blue nile material shown by high ti al values of the bulk sediment indicating dry conditions in the source area of the blue nile nile discharge increased from similar to 11 5 cal kyr bp and was high across the whole delta from similar to 10 6 5 cal kyr bp during this time the ti al values decreased within most nile delta sediments suggesting that the relative contribution of blue nile sediment decreased this was likely due to an increased vegetation cover causing diminished erosion in the ethiopian highlands nile discharge gradually decreased from similar to 6 5 cal kyr bp to present this decrease was more abrupt in the western province of the delta and became more gradual towards the east as the shrinking nile runoff was directed there the gradual decrease in precipitation in the nile catchment area seems not to be matched by a gradual response in vegetation growing around the river plain in the lower nile catchment our findings suggest a nonlinear response of northeast african vegetation to precipitation from the middle to late holocene c 2015 elsevier ltd all rights reserved

an onshore bathyal record of tectonics and climate cycles at the onset of the early middle pleistocene transition in the eastern mediterranean early pleistocene calabrian clays of the lindos bay formation have been uplifted and are exposed today on the eastern coast of rhodes hellenic forearc greece the hemipelagic origin of these sediments and the excellent preservation of the microfossils they contain make the lindos bay formation a unique element in the eastern mediterranean which has the potential to constitute a paleoclimate referential framework of the region for the early middle pleistocene transition empt in this context 98 samples were collected in the type locality section of the lindos bay formation stable isotope 18o 13c analyses were carried out on benthic uvigerina peregrina and planktonic globigerina bulloides foraminifera for the interval between 1100 ka and 858 ka we identify and continuously reconstruct the climate cycles that occurred between marine isotope stages mis 32 and 21 counts of planktonic foraminifera were further carried out and allow connecting the conditions occurring locally in the surface waters with the glacial interglacial cycles during the onset of the empt while sub tropical taxa dominate the assemblages glacials were associated with short term 10 kyr influxes of temperate to subpolar species suggesting cooling and or increasing productivity in the surface waters correlating with the deposition of sapropels in the eastern mediterranean deep sea finally planktonic benthic foraminiferal ratios show that the section deposited at upper bathyal depths between 450 m and 150 m during the late early pleistocene the eastern coast of rhodes has locally undergone repeated transient and possibly very rapid vertical motions which are overprinted on a regional tectonically forced regressive trend

chronology of the middle upper pliocene succession in the strongoli area constraints on the geological evolution of the crotone basin southern italy the aim of this study is to reconstruct the evolution of the strongoli area a critical sector of the crotone basin calabria southern italy where a thick middle upper pliocene marine succession is present the strongoli succession shows prominent changes in the sedimentary environment that are partly forced by tectonics major tectonostratigraphic events have been recognized that might correlate with spreading pulses in the back arc tyrrhenian sea in particular we demonstrate that a dramatic basinal collapse at c 2 3 ma correlates with the so called calabrian transgression auctorum and is close in age to the oceanization of the marsili basin

mg ca in the planktonic foraminifera globorotalia inflata and globigerinoides bulloides from western mediterranean plankton tow and core top samples abstract due to its strong gradient in salinity and small temperature gradient the mediterranean provides an ideal setting to study the impact of salinity on the incorporation of mg into foraminiferal tests we have investigated tests of globorotalia inflata and globigerina bulloides in plankton tow and core top samples from the western mediterranean using icp oes for bulk analyses and la icp ms for analyses of individual chambers in single specimens mg ca observed in g inflata are consistent with existing calibrations whereas g bulloides had significantly higher mg ca than predicted particularly in core top samples from the easterly stations scanning electron microscopy and laser ablation icp ms revealed secondary overgrowths on some tests which could explain the observed high core top mg ca we suggest that the mediterranean intermediate and deep water supersaturated with respect to calcite cause these overgrowths and therefore increased bulk mg ca however the different species are influenced by diagenesis to different degrees probably due to different test morphologies our results provide new perspectives on reported anomalously high mg ca in sedimentary foraminifera and the applicability of the mg ca paleothermometry in high salinity settings by showing that 1 part of the signal is generated by precipitation of inorganic calcite on the foraminifer test due to increased calcite saturation state of the water and 2 species with high surface to volume shell surfaces are potentially more affected by secondary mg rich calcite encrustation

holocene atmosphere ocean interactions records from greenland and the aegean sea we compare paleoclimate proxy records from central greenland and the aegean sea to offer new insights into the causes timing and mechanisms of holocene atmosphere ocean interactions a direct atmospheric link is revealed between aegean sea surface temperature sst and high latitude climate the major holocene events in our proxies of aegean sst and winter spring intensity of the siberian high gisp2 k record follow an 2300 year spacing recognised also in the 14c record and in worldwide holocene glacier advance phases suggesting a solar modulation of climate we argue that the primary atmospheric response involved decadal centennial fluctuations in the meridional pressure gradient driving aegean sst events via changes in the strength duration and or frequency of northerly polar continental air outbreaks over the basin the observed natural variability should be accounted for in predictions of future climate change and our timeframe for the aegean climate events in addition provides an independent chronostratigraphic argument to middle eastern archaeological studies

late quaternary changes in mediterranean intermediate water density and formation rate three recently acquired eastern mediterranean cores containing late quaternary sediments display a marked faunal contrast between the holocene and older sapropels it is suggested that the absence of neogloboquadrinids in the holocene sapropel and their abundance in older sapropels reflect differences in food availability related to the extent of development of a deep chlorophyll maximum layer dcm and the intensity of new primary production associated with this layer the depth of such a layer which consists of phytoplankton with a characteristic taxonomic composition is determined by the vertical hydrodynamical structure during deposition of the older sapropels the pycnocline was apparently positioned well above the base of the euphotic layer a situation that favors a pronounced dcm and an associated relatively high rate of new production shallowing of the pycnocline implies a relatively low density of the mediterranean intermediate water miw on the other hand during deposition of the holocene sapropel the pycnocline had apparently vanished due to termination of miw formation

some features of the algerian current an analysis of infrared images leads to a new conception of the dynamics of the atlantic water in the algerian basin in situ current measurements are not yet available but coherent hypotheses are presented with the aim to initiate further experimental and theoretical works the algerian current flows steadily along the coast near 0 and becomes unstable near 1 2 e eddies of both signs are generated that are advected by the mean current but only the anticyclonic eddies increase in size diameter about 100 km as they extract more energy from the mean current they are advected more slowly and they may detach from the coast and drift for several weeks in the algerian basin they grow as deep as 1000m at least and they are able to pull lenses of intermediate water seaward from the sardinian continental slope coastal upwelling cells are generated near 1 2 e between the cyclonic and the anticyclonic eddies they are also advected by the mean current and are definitively not wind induced these turbulent structures create intense mixing between the atlantic and mediterranean waters which account for the large eastward gradient of salinity encountered in the surface layer therefore the algerian basin is characterized by a large mesoscale variability mainly due to the instability of the algerian current it appears to be a reservoir in which the water of atlantic origin is amassed and it forms a buffer zone which disconnects the flow of atlantic water coming in at gibraltar from the flow of hygly modified atlantic water exiting the basin through the strait of sardinia and into the ligurian sea

integrated stratigraphic reconstruction for the last 80 kyr in a deep sector of the sardinia channel western mediterranean abstract a quantitative analysis of planktonic foraminifera coupled with petrophysical and paleomagnetic measurements and 14 c ams calibrations was carried out on a deep core recovered in the sardinia channel western mediterranean sea during the ciesm sub2 survey providing an integrated stratigraphic time framework over the last 80 kyr significant changes in the quantitative distribution of planktonic foraminifera allowed the identification of several eco bioevents useful to accurately mark the boundaries of the eco biozones widely recognized in the western mediterranean records and used for large scale correlations namely 10 eco biozones were identified based on the relative abundance of selected climate sensitive planktonic foraminiferal species sixteen codified eco bioevents were correlated with alboran sea planktonic foraminiferal data and several climatic global events sapropel s1 younger dryas greenland isotope interstadial 1 greenland isotope stadial 2 heinrich event h1 h6 were recognized the eco bioevents together with the 14 c ams calibrations allowed us to define an accurate age model spanning between 2 and 83 kyr the reliability of the age model was confirmed by comparing the colour reflectance 550 nm data of the studied record with the astronomically tuned record from the ionian sea odp site 964 a mean sedimentation rate of about 7 cm kyr included three turbidite event beds that were chronologically constrained within the relative low stand and regressive sea level phases of mis 4 and 3 the deep sea sedimentary record includes a distinct tephra occurring at the base of the core that dates 78 ka cal bp the paleomagnetic data provide a well defined record of the characteristic remanent magnetization that may be used to reconstruct the geomagnetic paleosecular variation for the mediterranean back to 83 kyr

the origin and characteristics of the algerian current satellite and ship data collected between may 1 and 22 1986 show that the algerian current originates in the almeria oran front and remains within 30 km of the algerian coast for over 300 km between oran and algiers the differences between the water masses of the current and the resident regional waters are clearly observed in the chlorophyll concentrations and optical characteristics thus permitting the resulting patterns to be used as tracers of the circulation during this field period the algerian current begins as an extension of the almeria oran front which is found at the western periphery of the eastern alboran gyre this major oceanographic salinity front s 1 km delineates the boundary of the algerian current which has average surface velocities of 40 cm s and maximum speeds reaching 80 cm s the current which has a volume transport between 0 4 and 0 5 sv is confined to the upper 150 m and is in geostrophic balance a sequence of coastal zone color scanner czcs and advanced very high resolution radiometer avhrr satellite imagery showing the rapidly evolving surface circulation features is augmented with in situ ship data of current and water mass characteristics rapid undulations and frontal movements of the current were observed during the study period however the flow remained unbroken between 1 and 3 e current instability increased eastward as the undulations were sharper and the current appeared to depart from the coast near algiers

the miocene pliocene boundary in the mediterranean area new insights from a high resolution micropalaeontological and cyclostratigraphical study cava serredi section central italy abstract tuscany central italy is a key area for studying the messinian salinity crisis and overlying lower pliocene deposits due to the high number and excellence of the outcrops although the miocene pliocene transition is well exposed and suitable for detailed analyses a high resolution integrated stratigraphic study of such a crucial time span for the geological history of the mediterranean has never been attempted in the fine basin central tuscany the cava serredi section is one of the best exposures of the upper messinian lower pliocene transition of the northern apennines the miocene pliocene boundary corresponds to a surface separating thinly laminated lacustrine lago mare marls from homogeneous circalittoral to upper bathyal marly clays detailed quantitative micropalaeontological analyses have been performed on 111 samples from the 22 m thick lower pliocene succession they resulted in the improvement of the biostratigraphic resolution of the basal zanclean interval due to the recognition of several chronologically constrained bioevents typical of the mediterranean region and based on benthic and planktonic foraminifera and calcareous nannofossils moreover to unravel cyclical patterns of deposition and given that the investigated succession shows no evident lithological pattern micropalaeontological analyses have been coupled with calcium carbonate content variations the latter revealed more regular fluctuations which are especially evident if the exclusive contribution of the planktonic foraminifer fraction p caco 3 is considered spectral analysis of the caco 3 curve indicates that sedimentation occurred under the control of earth s precession this datum is also confirmed by the cyclical patterns of neogloboquadrina acostaensis and sphenolithus spp among foraminifers and nannofossils respectively according to the proposed cyclostratigraphic and astrochronological reconstruction the lower pliocene interval of the cava serredi section consists of eight precession controlled cycles ranging from the i cycle 510 5 33 ma to the i cycle 494 5 16 ma finally the comparison with other astronomically calibrated sections including the zanclean gssp eraclea minoa sicily allowed us to prove the completeness of the basal zanclean interval of the study section and to state that pliocene re flooding after the messinian salinity crisis occurred synchronously with respect to other deeper sectors of the mediterranean basin

geochemical and micropaleontological characterisation of a mediterranean sapropel s5 a case study from core ban89gc09 south of crete several geochemical and micropaleontological proxies were studied in a well developed sapropel s5 from a core collected south of crete to investigate the causes and the mechanisms of its deposition to reconstruct the paleoenvironmental and paleoceanographical conditions at time of its formation and to detect the roles played by productivity and anoxia the geochemical proxies are also used to unravel the sediment provenance and therefore to help tracing water circulation patterns and freshwater sources the multiproxy approach reveals that the sapropel layer has high internal variability and five different depositional phases can be identified four within the visible sapropel layer an increase in temperature and the development of a deep chlorophyll maximum characterise the onset of the sapropel phase 1 with enhanced productivity being favoured by local riverine input not clearly ascribable to nile river freshwater discharge and by the shoaling of the pycnocline nutricline surface water stratification and productivity develop together with strong seafloor dysoxia anoxia phase 2 is characterised by lower stratification slightly lower temperature and or higher seasonal contrast and still high productivity phase 3 records high productivity high temperature and high stratification probably more sustained by the nile input a sudden partial re oxygenation takes place at the end of this phase changing the main features of the sapropel in the fourth phase productivity starts to decrease water stratification seems to be partially broken down and sediment oxygenation increases a transitional phase phase 5 occurs between the end of the visible sapropel and the normal pelagic post sapropel sedimentation where productivity is still high and oxygenation improves compared to the visible sapropel layer the massive occurrence of polysphaeridium zoharyi cyst of a red tide forming dinoflagellate also characterises this phase the geochemical proxies indicate that pre sapropel and post sapropel sediments are quite different from each other and the provenance shifts from a more mixed to a more markedly southern origin of sediments

increasing seasonal upwelling in the subtropical south atlantic over the past 700 000 yrs evidence from deep living planktonic foraminifera abstract the distribution and character of deep living planktonic foraminifera such asgloborotalia truncatulinoides andg hirsuta are particularly sensitive to the structure of the upper ocean because of the wide range of water depths over which their life cycles extend like other planktonic foraminifera the deep living species begin growing in shallow surface waters but unlike the other species they continue growing while sinking into much deeper water their reproduction is synchronized with the seasonal deep mixing and upwelling of nutrient rich waters that precedes spring bloom where deep mixing is curtailed the abundances of the deeper dwelling species g hirsuta the deeper dwelling varieties e g left coilingg truncatulinoides and the larger presumably faster sinking shells are reduced leading to an apparent acceleration in shell development these changes are observed today in transects from the seasonally deep mixed subtropical gyres to the seasonally stable surface waters equatorward of the subtropical convergences past changes in the abundance and character of these deep living planktonic foraminifera have been measured in a late pleistocene record from the subtropical western south atlantic ocean over the past 700 kyrs abundances of these species have increased g truncatulinoides has changed from the predominantly shallower dwelling right coiling to the deeper dwelling left coiling variety and the accelerated shell development characteristic of shallow mixing has shifted toward the rates normally associated with deep mixing all this indicates that the structure of the upper ocean in the subtropical south atlantic before 700 kyrs ago was more like that nearer the equator today where mixing is limited to the upper 100 200 m since that time the scale of mixing has gradually increased to more than 400 m this implies a gradual increase through the late pleistocene in the seasonal upwelling of nutrients in the subtropical south atlantic and consequently in the intensity of the seasonal maximum in organic productivity

lithospheric structure of the aegean obtained from p and s receiver functions combined p and s receiver functions from seismograms of teleseismic events recorded at 65 temporary and permanent stations in the aegean region are used to map the geometry of the subducted african and the overriding aegean plates we image the moho of the subducting african plate at depths ranging from 40 km beneath southern crete and the western peloponnesus to 160 km beneath the volcanic arc and 220 km beneath northern greece however the dip of the moho of the subducting african plate is shallower beneath the peloponnesus than beneath crete and rhodes and flattens out beneath the northern aegean observed p to s conversions at stations located in the forearc indicate a reversed velocity contrast at the moho boundary of the aegean plate whereas this boundary is observed as a normal velocity contrast by the s to p conversions our modeling suggests that the presence of a large amount of serpentinite more than 30 in the forearc mantle wedge which generally occurs in the subduction zones may be the reason for the reverse sign of the p to s conversion coefficient moho depths for the aegean plate show that the southern part of the aegean crustal thickness of 20 22 km has been strongly influenced by extension while the northern aegean sea which at present undergoes the highest crustal deformation shows a relatively thicker crust 25 28 km this may imply a recent initiation of the present kinematics in the aegean western greece crustal thickness of 32 40 km is unaffected by the recent extension but underwent crustal thickening during the hellenides mountains building event the depths of the aegean moho beneath the margin of the peloponnesus and crete 25 28 and 25 33 km respectively show that these areas are also likely to be affected by the aegean extension even though the cyclades crustal thickness of 26 30 km were not significantly involved in this episode the aegean lithosphere asthenosphere boundary lab mapped with s receiver functions is about 150 km deep beneath mainland greece whereas the lab of the subducted african plate dips from 100 km beneath crete and the southern aegean sea to about 225 km under the volcanic arc this implies a thickness of 60 65 km for the subducted african lithosphere suggesting that the aegean lithosphere was not significantly affected by the extensional process associated with the exhumation of metamorphic core complexes in the cyclades

foraminiferal record and environmental changes during the deposition of the early middle pleistocene sapropels in southern italy a foraminiferal investigation documents the palaeoenvironmental changes across the sapropel units associated with insolation cycles 90 and 86 in the early middle pleistocene im fosso 5 agosto section basilicata southern italy three benthic foraminiferal fossil associations associations a b and c identified by performing hierarchical cluster analysis on the quantitative data can be considered diagnostic of the palaeoenvironmental conditions before during and after the sapropel intervals they indicate a gradual decrease of bottom water oxygenation prior to the onset of sapropel deposition and a rapid return to stable environmental conditions at the end of the sapropel events the constant presence of benthic foraminifera throughout the sapropels implies that the bottom environment was not totally anoxic the high resolution distributional pattern of planktonic and benthic foraminifera within the sapropel associated with i cycle 90 documents a surface water cooling with consequent rapid re oxygenation of bottom waters that subdivides this interval in two phases both of them are characterized by an early subphase with warm climate conditions a decrease of salinity in surficial water layers and dominated by the low oxygen tolerant benthic species globobulimina affinis the late subphase shows thermal stratification during summer and a relatively deep and oxygenated mixed layer during winter in this subphase the contemporaneous replacement of g affinis the bless opportunistic but more resistant to low oxygen conditionsq species with bolivina alata bolivina dilatata and brizalina spathulata the bless resistant to low oxygen conditionsq species indicates the relative oxygen improvement in sediment pore water the frequent changes detected in the sapropel associated faunal composition underline the unstable nature of bottom water oxygen content d 2004 elsevier b v all rights reserved

high frequency climate fluctuations over the last deglaciation in the alboran sea western mediterranean evidence from calcareous plankton assemblages abstract a high resolution study with a centennial scale resolution has been performed on the calcareous plankton assemblage coccolithophores and planktonic foraminifera at ocean drilling program site 976 alboran sea western mediterranean focusing on the interval between 20 and 9 ka in order to reconstruct changes in surface and subsurface water dynamics and productivity the biotic surface water proxies integrate the extremely detailed multi decadal scale geochemical data set and the pollen record already available at the core thus providing a complete paleoenvironmental paleoceanographic reconstruction the results highlight the sensitivity of the calcareous plankton in recording stadial interstadial phases and higher frequency climatic events that produced changes in sea water features wind induced upwelling and river discharge during the last glacial period favored nutrient availability and moderate productivity during heinrich stadial 1 hs1 the arrival of cold and fresher waters from iceberg melting in the north atlantic significantly hampered productivity at its lowest values of the whole investigated interval calcareous plankton behavior supports the hypothesis that hs1 is a composite event marked by three phases hs1a characterized by the coldest sst polar atlantic water inflow into the basin and a first step toward a dry climate on the continent hs1b recording enhanced freshwater inflow and drought on land and hs1c indicating reduced polar water influx the bolling allerod ba interstadial sees the highest rate of productivity in the entire interval and accompanies the deposition of organic rich layer 1 during the ba coccolithophore assemblage also marks higher frequency changes in hydrographic conditions apparently in relation with greenland interstadial i gi i high variability the younger dryas stadial yd is characterized by refunding cold and dry conditions although not as severe as during hs1 and by enhanced detrital input in surface water during drier conditions on land the holocene onset records climate amelioration both in the marine and continental environment although coccolithophore productivity is not as high as during the ba the rapid shifts in climate sensitive taxa support the hypothesis that each of the climate phases subphases is characterized by a complex pattern forced by strong interaction between ice sheet instability meltwater discharge entering the gibraltar strait north atlantic westerlies and moisture availability clearly impacting over surface water temperature productivity and land masses

sediment trap and deep sea coretop sediments as tracers of recent changes in planktonic foraminifera assemblages in the southeastern ultra oligotrophic levantine basin abstract sediment trap and core top sediments were used to study the seasonal and longer term variability in the distribution and assemblage composition of planktonic foraminifera pf in the ultra oligotrophic eastern mediterranean levantine basin lb a continuous time series of particulate flux sampled every 11 12 days were retrieved from a sediment trap deployed at 1300 m between may 2017 and may 2018 the core top sediments were collected close to the sediment trap mooring site at 1500 m water depth the average annual planktonic foraminiferal pf flux was 93 shells m 2 d 1 the lowest value yet recorded among traps located in tropical subtropical oligotrophic regions a bimodal increase in pf flux is observed with highest numbers of 452 shells m 2 d 1 occurring in winter february responding directly to maxima in particulate mass flux a lower flux occurs in late summer from mid august to mid september with up to 197 shells m 2 d 1 ten species were found in the trap the majority were symbiont bearing spinose species that contribute 96 of the total flux globigerinoides ruber white predominate the assemblage composition during the winter peak together with globoturborotalita rubsecens and globigerinella calida during the subordinate summer peak the dominating species were g ruber white orbulina universa and globigerinoides ruber pink the relative abundance of g bulloides and g ruber pink is much lower in the sediment trap samples compared to their abundance in nearby coretop sediments this trend seems to indicate a recent drop in their numbers at the same time g rubescens and globoturborotalita tenella occur in higher numbers in the sediment trap compared with the coretop samples these opposite trends may reflect the current adjustment of certain pf species to the ongoing sea surface warming and decrease in food availability in the lb

temperature and salinity records of the tyrrhenian sea during the last 18 000 years abstract we have used the modern analogue technique to derive sea surface temperature sst records of the last 18 000 years from two well dated deep sea cores recovered in the tyrrhenian sea results show two major cooling events synchronous with the european and north atlantic oldest and younger dryas events a later cooling of lower amplitude is observed between about 8000 and 4500 yr bp tyrrhenian ssts were similar to those of the upper holocene only during the bolling allerod event and at the beginning of the holocene we compared the sst and the planktonic foraminiferal oxygen isotope records to estimate the surface salinity variations our reconstruction shows that salinity decreased in the tyrrhenian sea during the three cold events whereas high ssts correlate with high salinities during most of the last 18 000 years tyrrhenian sea salinity variations were similar to those of the north atlantic ocean near the entrance of the mediterranean sea the salinity gradient between the two basins was thus constant indicating that the western mediterranean circulation pattern and the freshwater budget were not significantly different from the modern one the case was however different during the middle holocene when the strong salinity decrease associated with the sapropel deposit in the eastern mediterranean basin had no equivalent in the north atlantic ocean this peculiar event can only be explained by a local climatic change and an increase of precipitation

palaeoceanography of the last deglaciation in the alboran sea western mediterranean stable isotopes and planktonic foraminiferal records abstract oxygen isotope changes of the foraminiferal species globigerina bulloides and uvigerina peregrina eleven radiocarbon dates on the sediment fraction above 50 m and 13 biostratigraphical events allow us to correlate and to date the sediment record of the last climatic cycle in four cores from the alboran sea nine ecozones are recognized which differ from those previously established for atlantic sediments cored immediately west of gibraltar these ecozones can be grouped into two broad phases from the last glacial maximum up to near 9 500 yr b p cold north atlantic microfaunas are the major component of the assemblages during this interval dominant species replace each other according to the varying temperature and density stratification of the water masses from 9 500 yr b p up to the present time subtropical forms from the central atlantic dominate the northern atlantic forms an abrupt increase in the percentages of g inflata occurred near 7 000 b p this event was diachronous within the mediterranean during the last glacial g inflata was endemic inside the mediterranean and its abrupt increase near the end of the deglaciation did not result from replenishment from the atlantic between 4 000 and 5 000 yr b p percentages of g bulloides also increased abruptly warming conditions associated with the onset of a seasonal thermal stratification and a contrasting winter vertical convection are strongly suggested

planktonic foraminiferal flux to the deep ocean sediment trap results from the tropical atlantic and the central pacific abstract the flux of planktonic foraminifera between 100 m and 1 mm to the seafloor has been estimated for the central pacific abyssal plain east of hawaii and the tropical atlantic demerara abyssal plain based on sediment trap samples collected from various water depths the faunas in each region are quite similar with 4 to 5 species generally accounting for 70 80 of the total assemblage at both study sites the total foraminiferal flux and the carbonate flux tend to decrease with depth in addition the flux of individual species of planktonic foraminifera varies significantly with depth with the number of small solution susceptible species decreasing with increasing water depth these results suggest that there is significant dissolution of small m foraminifera as they settle through the water column material collected from the sediment water interface directly below the pacific sediment trap array contains no planktonic foraminifera suggesting that the residence time of an individual on the seafloor before it dissolves is extremely short

precession related sapropelites of the messinian sorbas basin south spain paleoenvironmental significance abstract the sorbas basin southern spain is a narrow and elongated basin located in the betic corridor that formed the northern connection between the atlantic and the paleomediterranean during the late miocene in the centre of the basin about 120 m of well preserved cyclic marine sediments crop out ranging in age from 7 2 to 6 myr these cycles make up the abad member and are an excellent example of precession control over sedimentation in the upper part of the sequence upper abad member the cycles include organic rich laminated brown marls sapropelites alternating with homogeneous marls displaying diatomite layers the om rich laminated marls are the westernmost sapropelites of the mediterranean this paper is a geochemical mineralogical sedimentological and micropaleontological analysis of three cycles with sapropelites the data enable us to distinguish two main climatic scenarios the climate which dominated each of these scenarios regulated the sedimentology and the physico chemistry of the water column resulting in the sapropelite homogeneous marl cyclic alternations the sapropelites developed during a climate characterised by a long period of temperate and humid conditions that occur at times of precession minima these climatic conditions changed progressively to a subarid and drier weather during which homogeneous sediments were deposited the changes between these scenarios were gradual as expected from precession dynamics our data suggest that the change from the subarid to the humid climate transition from homogeneous marls to laminated sapropelites took place at a faster rate or at least was recorded more rapidly by the sediments than the transition from the humid interval to the sub arid period

short term climate changes in the southern aegean sea over the last 48 000 years abstract high resolution palaeoenvironmental changes corresponding to a mean time interval of 450 years covering the last 48 000 years were examined in a core from the cretan basin in the southern aegean sea the intensity and duration of the climatic and oceanographic events were determined by examining the compositional changes in the planktonic foraminifera and pollen assemblages along with the 18o signal of globigerinoides ruber a reconstruction of sea surface temperatures was attempted using the modern analogue technique mat in total 10 stadials and 6 interstadials occurred over the last 48 000 years these fluctuations in climatic conditions coincide with fluctuations documented in the western and central mediterranean and seem to be associated with dansgaard oeschger events some of these climatic fluctuations are correlated with changes in the vegetation in the surrounding land between 48 and 10 cal kyr bp the most pronounced stadials occurred at 41 cal kyr bp c69 st10 and at 13 cal kyr bp c69 st4 these events are characterized by i high positive 18o values of globigerinoides ruber ii drops in sst and iii increases in aridity these events may be correlated with the heinrich h4 event and the younger dryas event respectively two other stadials at 23 cal kyr bp c69 st6 and at 16 cal kyr bp c69 st5 which are characterized by increases in the abundance of the cold plaktonic foraminifera species and increases in aridity may be correlated with the h2 and h1 events respectively the dominant planktonic foraminiferal species during the stadials witch are correlated with the heinrich events were turborotalita quinqueloba and globorotalia scitula the most pronounced interstadials occurred between 39 5 and 38 5 cal kyr bp c69 ist6 and between 25 and 24 cal kyr bp c69 ist3 and are characterized by depletion in 18o values increases in sst and increases in humidity the former event coincides with the formation of the sapropelitic layer s2 in the holocene the most pronounced stadial occurred between 8 and 6 5 cal kyr bp c69 st2 during the interruption of s1 and is characterized by a reduction in sst and an increase in aridity the most pronounced interstadials of holocene occurred during the formation of s1a and s1b between 9 and 8 cal kyr bp c69 ist1 and between 6 5 and 5 5 cal kyr bp c69 ist2 respectively these events are characterized by depletion in 18o values increased sst and an increase in humidity as is indicated by the expansion of temperate evergreen and mediterranean taxa in the pollen record

the valle di manche section calabria southern italy a high resolution record of the early middle pleistocene transition mis 21 mis 19 in the central mediterranean abstract the on land marine valle di manche section crotone basin calabria southern italy one of the candidates to host the gssp of the middle pleistocene ionian stage preserves a manifold record of independent chronological paleoclimatic and stratigraphic proxies that permit a straightforward correlation with marine and terrestrial reference records at the global scale in particular the section holds an excellent record of the matuyama brunhes magnetic reversal which occurs in the midst of marine isotope stage mis 19 we report on a complete revision of the section that improves dramatically the available dataset especially in the stratigraphic interval straddling the lower middle pleistocene boundary our benthic 18o record provides evidence that the matuyama brunhes transition the stratigraphic position of which is marked by a prominent tephra the pitagora ash occurred during full mis 19 in agreement with many records worldwide we obtained an age of 786 9 5 ka for the matuyama brunhes magnetic reversal and pinpointed the paleomagnetic transition of to a 3 cm thick interval indicating that the event was very fast since the section fulfills all the requirements to host the gssp of the ionian stage we propose that the boundary should be placed at the base of the pitagora ash ca 12 5 cm below the midpoint of the matuyama brunhes reversal

surface and deep water conditions in the sicily channel central mediterranean at the time of sapropel s5 deposition abstract new centennial scale data of benthic foraminifera assemblages and of stable isotopes of foraminifera shells from the sicily channel representative of surface and bottom waters over the interval between about 140 and 110 kyr bp are presented during this period anoxia developed on the eastern mediterranean basin and sapropel s5 deposited although anoxic sediments have not been deposited in the sicily channel this area is strategic to study the character of intermediate waters whose chemical physical properties strongly precondition the eastern mediterranean deep water formation so far no data from these water masses have been obtained apart from the isotopic composition of shells of the planktonic foraminifera species neogloboquadrina pachyderma which lives at about 200 m depth thus quite far from the intermediate water core we conclude that although with a reduced rate the flowing of intermediate waters coming from the eastern basin together with the surface water masses with a clear western affinity implies the maintenance of an anti estuarine circulation pattern across the sicily channel and in the mediterranean sea also during one of the most severe episodes of anoxia of the late pleistocene

response of the pelagic environment to palaeoclimatic changes in the central mediterranean sea during the late quaternary abstract three central mediterranean deep sea cores have been studied to reconstruct the palaeoclimatic history of the basin over the time interval 34 0 kyr bp the intensity and duration of the climatic events that occurred in the mediterranean sea during the last glacial postglacial transition were estimated by observing compositional changes in the planktonic foraminifera and calcareous nannoplankton coccolithophores assemblages together with a reconstruction of sea surface temperatures using the modern analogue technique and u 37 k index the 18 o signal and pteropod fluxes the application of two independent and well established techniques for the determination of the past sst led to a number of considerations about the accuracy and efficacy of the use of such methodologies in the mediterranean sea notoriously dominated by local factors and characterised by a number of independent environments the recognition of millennial to centennial climatic instabilities in both the sst and microfossil records was possible because of the high resolution of the study a succession of nine main biozones and six sub zones based on the major changes in the planktonic foraminifera records has been recognised and compared with grip and gisp2 ice cores 18 o values and with records from four other studies from the central mediterranean sea during the early phase of the holocene a period characterised by relatively higher temperatures and lighter 18 o values has been recognised as being coeval with the climatic optimum between 10 5 and 6 1 kyr bp calendar age this interval was characterised by an abrupt drop in the pteropods relative abundances and fluxes the pteropodal fossil assemblage may have been affected by a possible event of selective dissolution of the aragonite driven by the shoaling of the acd a coeval change in the position of the pycnocline may have been responsible for a strong relative increase in abundance of neogloboquadrina pachyderma r c and a decrease in the abundance of globorotalia inflata in the western sector of the mediterranean sea

composition and temporal variability of particle fluxes in an insular canyon of the northwestern mediterranean sea abstract particle fluxes have been widely studied in canyons located in continental margins conversely particle fluxes in canyons in sediment starved margins incising small island margins have received very little attention and remain poorly understood the menorca canyon is the largest canyon system in the balearic archipelago despite the high oligotrophic conditions of the balearic archipelago the canyon and surrounding areas host diverse communities dominated by benthic suspension feeders understanding the magnitude and variability of environmental factors influencing these communities thus remain crucial in order to characterize the temporal variability of particle fluxes analyze its geochemical and macroscopic composition and identify the main processes that modulate particle fluxes in the menorca canyon one instrumented line with a sediment trap and a current meter was deployed at 430 m water depth from september 2010 to october 2012 particle fluxes ranged between 190 and 2300 mg m2 d 1 being one of the lowest ever registered in a mediterranean submarine canyon s head the caco3 fraction was the major constituent contrasting with the general trend observed in other mediterranean canyons macroscopic constituents fecal pellets posidonia oceanica detritus and pelagic and benthic foraminifera presented a wide variability throughout the sampling period and were not significantly correlated with the total mass flux the low magnitude of the registered fluxes and the lack of correlation with the observed environmental variables e g currents winds wave height chlorophyll a biomass suggest that there is no evident controlling mechanism however we could infer that resuspension processes and the presence of different hydrodynamic features e g eddies interchange of water masses condition the magnitude and composition of particle fluxes

population dynamics of living planktic foraminifers in the hemipelagic southeastern bay of biscay abstract population dynamics of planktic foraminifer species are discussed in relation to environmental factors across the continental slope onto the shelf of the southeastern bay of biscay along a bathymetric transect from 2000 m to 145 m water depth 154 vertical plankton tows were obtained during different seasons on five cruises between june 2006 and july 2008 the distribution of live specimens 100 m sampled at distinct intervals down to 700 m water depth is compared to changes in temperature salinity and chlorophyll a concentration the overall seasonal variability and depth distribution of species in the hemipelagic southeastern bay of biscay has been similar to open ocean faunas in the pelagic north atlantic each species examined occurred at considerable variability in habitat depth and seasonal distribution the vertical distribution of planktic foraminifer species was mainly driven by the depth of the deep chlorophyll maximum dcm and hence linked to the development of the thermocline the seasonal variation of river discharge could have had differential effects on the distribution of planktic foraminifers and may have inhibited or triggered the production of species low standing stocks at onshore stations in spring and high standing stocks in july both in low saline waters indicate that salinity in itself did not control the distribution of planktic foraminifers instead factors which co vary with salinity such as turbidity and organic matter possibly affected the distribution of planktic foraminifers on a species specific scale in general the distribution of planktic foraminifer species on a seasonal vertical and regional scale along the offshore onshore transect was related to surface water salinity and turbidity and to the availability of food

a study of an intense density front in the eastern alboran sea the almeria oran front abstract studies of satellite imagery and space shuttle photographs of the western mediterranean have indicated that the main path of inflowing atlantic water is around two large anticyclonic gyres in the alboran sea and along the algerian coast these studies have also shown that a strong ocean front is present between almeria spain and oran algeria which is part of the easternmost segment of the eastern alboran gyre based on these satellite studies the first in situ investigation of the front called here the almeria oran front was conducted in march 1986 as part of the winter campaign of the western mediterranean circulation experiment wmce analyses of the resulting data show that the almeria oran front is a large scale density front formed by the convergence of two distinct water masses and controlled by the geographic position and strength of the eastern alboran gyre physical and biochemical data indicate that the front is limited to the upper 300 m with a strong southward baroclinic jet

geographical and bathymetric distribution of foraminiferal assemblages from the alboran sea western mediterranean a total of 176 surface sediment samples recovered in the alboran sea by the oceanographic vessel vizconde de eza during the 2002 and 2003 campaigns were analysed for their foraminiferal content planktonic and benthic foraminifera were picked up studied and classified in addition a series of diversity indices were calculated an attempt was made to correlate diversity fisher alpha index with longitude latitude and depth planktonic assemblages are strongly dominated by the species globorotalia inflata d orbigny together with globigerina bulloides d orbigny correlation analysis show only a weak relation between planktonic foraminiferal diversity and both longitude and distance to the coast which in the alboran sea are strongly related with depth benthic assemblage diversity is correlated with longitude thus reflecting a west to east diversity increase pattern and with depth latitude and distance to the coast suggesting a diversity decrease with depth no significant correlation has been found between average chlorophyll concentration and either planktonic or benthic foraminiferal diversities a q mode hierarchical cluster analysis hca recognised four clusters with different bathymetric and geographical distribution cluster a mostly in the easternmost part of the studied area in the almeria gulf is composed of shallow highly diverse samples dominated by cibicidoides lobatulus walker jacob and textularia agglutinans d orbigny indicating current influenced environments with close algal or vegetation covered areas cluster b includes the deepest less diverse assemblages strongly dominated by the low oxygen tolerant species uvigerina mediterranea hofker and uvigerina peregrina cushman cluster c groups many outer shelf upper bathyal samples along the malaga and almeria coast with opportunistic species like u peregrina cassidulina laevigata d orbigny bulimina marginata d orbigny and u mediterranea that reflect abundant organic supply in an upwelling area and finally cluster d representing shallow relatively diverse samples mainly located on the alboran ridge and with predominating dorothia pseudoturris cushman textularia pseudorugosa lacroix elphidium crispum linne and c lobatulus related with coarse grained current influenced sediments and nearby vegetation covered areas

plankton ecology and the paleoceanographic climatic record the paleoceanographic climatic record represented by deep sea microfossils reflects conditions for only certain times of the year also the relative abundances of microfossil species in deep sea sediments do not usually reflect only one paleoceanographic variable such as temperature rather species distributions represent the integration of many factors that control biological production in the oceans this influences the information on past climates that can be extracted from fossil material the seasonal limitation is due to the cyclic nature of biological production in the open ocean case studies of the sediment record in the atlantic for two species of planktonic foraminifera left coiling neogloboquadrina pachyderma ehrenberg and globigerinoides ruber d orbigny illustrate seasonal bias in environmental data reported by the relative abundances of species in deep sea sediments in addition the study of g ruber illustrates the operation of two oceanographic parameters in controlling a species distribution these examples demonstrate that the environmental signal in the sediments is the result of the interplay of the ecological tolerance of the plankton species with seasonally variable biological and physical properties of the upper ocean

mediterranean pluvial periods and sapropel formation over the last 200 000 years abstract three mediterranean deep sea cores have been studied to reconstruct the hydrological conditions at the time of deposition of interglacial and glacial sapropels during the time interval 200 60 kyr bp the isotopic and sea surface temperature records of planktonic foraminifera were used to estimate the oxygen isotopic composition of surface water w in the tyrrhenian sea and levantine basin our results show a strong w salinity decrease in both basins associated with each sapropel these w decreases reflect a drastic change in the local freshwater budget and were comparable to that observed during the last sapropel s 1 centred at ca 8 kyr bp a strong precipitation increase transformed the whole mediterranean sea into a non concentration basin the low surface salinity was responsible for the water column stratification while nutrients brought in by the runoff enhanced productivity it resulted in a significant reduction in the rate of deep water oxygenation and sapropel formation in the eastern basin in addition the mediterranean sea 18 o record is very similar to that of the bay of bengal as the latter is very sensitive to the summer monsoon rain this similarity suggests that both glacial and interglacial sapropels result from enhanced monsoon like precipitation due to an increase in summer insolation driven by precession variations

central mediterranean mid pleistocene paleoclimatic variability and its association with global climate abstract planktonic foraminiferal assemblages were studied at high resolution in core kc01b from the ionian sea quantitative analysis allowed us to distinguish the main climatic features and associated paleoceanographic changes that occurred between marine isotopic stages mis 13 and 9 500 300 ka mis 12 and mis 10 are characterized by relatively temperate conditions and an oligotrophic oceanographic regime in the early part and by colder conditions and nutrient supply in the sub surface water masses in the upper part during these intervals small but distinct peaks of neogloboquadrina pachyderma sinistral sin are detected at times of extremely negative values of the planktonic foraminifera paleoclimatic curve their co occurrence with similar episodes in the atlantic suggests that the climate in the central mediterranean was associated with north atlantic millennial scale climate instability mis 11 and mis 9 are dominated by surficial warm water taxa the climate optimum is reached in the middle part of each of these stages as denoted by the presence of globigerinoides sacculifer and persists for approximately 20 and 6 ka during mis 11 and mis 9 respectively this warming is not constant but is characterized by three distinct intervals with elevated winter temperatures and or weak winter mixing distribution of globigerina bulloides turborotalita quinqueloba and n pachyderma dextral dex indicates that significant environmental changes occur across the transitions from glacial to interglacial mis 12 mis 11 termination v and mis 10 mis 9 termination iv the studied record documents a close linkage between mediterranean climate evolution and higher and lower latitude climate change throughout mis 13 9