morphology and environment of cold water coral carbonate mounds on the nw european margin cold water coral carbonate mounds owing their presence mainly to the framework building coral lophelia pertusa and the activity of associated organisms are common along the european margin with their spatial distribution allowing them to be divided into a number of mound provinces variation in mound attributes are explored via a series of case studies on mound provinces that have been the most intensely investigated belgica hovland pelagia logachev and norwegian mounds morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the environmental conditions under which mounds are initiated and grow cold water coral carbonate mounds can be divided into those exhibiting inherited morphologies where mound morphology reflects the morphology of the colonised features and developed morphology where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls finer scale surface morphological features mainly reflecting biological growth forms are also discussed

productivity controlled cold water coral growth periods during the last glacial off mauritania abstract article history received 17 june 2010received in revised form 29 october 2010accepted 11 december 2010available online 21 december 2010communicated by g j de langekeywords lopheliacold water coralscarbonate moundsbanda mound provincenw africaprimary productivity cold water corals are widely distributed along the atlantic continental margin with varying growth patternsinrelationtotheirspeci cenvironment here weinvestigatethelong termdevelopmentofcold watercoralsthat once thrived on a low latitude 17 40 n cold water coral mound in the banda mound province offmauritania duringthelastglacial interglacialcycle u thdatesobtained from20specimensofthecold watercoral lophelia pertusa revealed three distinct periods of coral growth during the last glacial at 65 to 57 kyr bp 45 to 32 kyr bp and 14 kyr bp thus comprising the cool periods of marine isotopic stages mis 2 4 thesecoral growth periods occur during periods of increased productivity in the region emphasizing thatproductivity seems to be the major steering factor for coral growth off mauritania which is one of the majorupwelling regions in the world this pattern differs from the well studied coral mounds off ireland where thecurrent regime predominantly in uences the prosperity of the cold water corals moreover coral growth offireland takes place during rather warm interglacial and interstadial periods whereas off mauritania coralgrowth is restricted to glacial and stadial periods however the on mound sedimentation patterns offmauritania largely resemble the observations reported from the irish mounds the bulk of the preservedsediments derives from periods of coral growth whereas during periods without corals hardly any netsedimentation or mound growth took place 2011 elsevier b v all rights reserved

age constraints on the origin and growth history of a deep water coral mound in the northeast atlantic drilled during integrated ocean drilling program expedition 307 sr isotope stratigraphy provides a new age model for the first complete section drilled through a deep water coral mound the 155 m long section from challenger mound in the porcupine sea bight southwest of ireland is on miocene siliciclastics and consists entirely of sediments bearing well preserved cold water coral lophelia pertusa the 87sr 86sr values of 28 coral specimens from the mound show an upward increasing trend correspond to ages from 2 6 to 0 5 ma and identify a significant hiatus from ca 1 7 to 1 0 ma at 23 6 m below seafloor the age of the basal mound sediments coincides with the intensification of northern hemisphere glaciations that set up the modern stratification of the northeast atlantic and enabled coral growth mound growth persisted throughout glacial interglacial fluctuations reached a maximum rate 24 cm k y ca 2 0 ma and ceased at 1 7 ma unlike other buried mounds in porcupine seabight challenger mound was only partly covered during its growth interruption and growth restarted ca 1 0 ma

aeolian dust in europe african sources and european deposits abstract a conceptual model is presented for the provenance and dispersal patterns of small dust that falls on europe generally its sources are in north africa and it is distributed across all europe several key sources can be distinguished sahelian dust comes largely from the old lake chad region this is a clay rich unimodal material saharan dust comes from the great sand sheets it contains small monomineralic particles and may have a bimodal size range three simple deposition zones can be recognised a d1a zone where sufficient dust is deposited to form a discrete soil layer not well classified as a rendoll in the extreme south of europe a d1b zone where the airborne dust simply provided a silty admixture to soil systems across middle europe and a northern zone d1c where the dust is a fugitive cloud but very occasionally forms noticeable deposits two particle formation methods can be noted particle control in sahelian dust is via the sedimentation in the original lake this gives an open structure which can be modelled using a simple monte carlo approach the open structure ensures that only small particles are produced size control is via particle packing a chipping mechanism can produce fine quartz particles from sandy deserts the aeolian energy is by and large not sufficient to cause major impact fracturing but small mineral chips can be produced in the small dust size fine and very fine silt which go into high level suspension and travel to europe and beyond the saharan material can have a wider more variable size distribution than the sahelian material the canary islands loess is largely sahelian material the cape verde islands deposits from the nearby sandy regions are saharan deposits large dust has fallen on europe and produced widespread loess deposits large dust is essentially an in continent deposit small dust comes from outside from africa

cosmogenic nuclides and the dating of lateglacial and early holocene glacier variations the alpine perspective abstract based on cosmogenic 10 be data from four sites in the alps we discuss geological uncertainties associated with the dating of former cirque and small valley glacier margins at the early lateglacial gschnitz site trins austria a 3000 yr spread in 10 be exposure ages points to prolonged boulder instability three out of seven ages are not included in the mean age calculation which yielded 15 400 1000 yr indistinguishable from the oldest boulder age of 16 130 1040 yr as a result of the distinctive morphology at julier pass switzerland site we are able to exposure date the early 12 300 1300 yr and the late 11 300 600 yr egesen stadial glacier advances younger dryas equivalent not just final retreat at the kromer site austria 10 be exposure ages from five clast supported boulders are indistinguishable within the analytical uncertainties mean age 8400 500 yr in addition to moraine age key factors that may lead to too young ages include degree of matrix vs clast support of the boulders post depositional periglacial activity and tree coverage at the nagelisgratli bedrock site near grimsel pass switzerland exposure ages of 10 760 11 720 yr are consistent with early holocene cirque glacier retreat and underline the marked lack of nuclide inheritance in bedrock exposures in the alps

geochemical and physical constraints for the occurrence of living cold water corals cold water coral communities cover a wide range of possible habitats in terms of latitude ocean basins and depth with ongoing studies continually expanding occurrences in various regions of the global ocean a range of factors determines the formation of cold water coral reefs such as physical hydrochemical and biological e g food supply factors recently more and more modeling studies have emerged using a variety of mathematical approaches have emerged including environmental niche factor analysis enfa and predictive habitat suitability models however only few studies have attempted to characterize the underlying suite of hydro biogeochemical and physical constraints of cold water coral reefs and to differentiate between pristine reef growth vs sites with reduced or no coral occurrences this study concentrates on new data and a compilation of existing data sets on the physical and chemical properties in the ne atlantic and the mediterranean it explores the influence of ambient bottom waters and its characteristics on living cold water reefs and mounds formed by lophelia pertusa several questions are addressed 1 what are the physical and geochemical boundary conditions of living cold water corals 2 do these geochemical parameters correlate with proposed physical prerequisites 3 is there a general difference in the signature of living and dead coral sites

growth and erosion of a cold water coral covered carbonate mound in the northeast atlantic during the late pleistocene and holocene the first detailed stratigraphic record from a deep water carbonate mound in the northeast atlantic based on absolute datings u th and ams 14c and stable oxygen isotope records reveals that its top sediment sequences are condensed by numerous hiatuses according to stable isotope data mainly sediments with an intermediate signal are preserved on the mound while almost all fully glacial and interglacial sediments have either not been deposited or have been eroded later the resulting hiatuses reduce the late pleistocene sediment accumulation at propeller mound to amounts smaller than the background sedimentation the hiatuses most likely result due to the sweeping of the mound in turn with the re establishment of vigour interglacial circulation patterns after sluggish current regimes during glacials thus within the discussion if internal fluid driven or external environmentally driven processes control the evolution of such carbonate mounds our findings for propeller mound clearly point to environmental forcing as the dominant mechanism shaping deep water carbonate mounds in the ne atlantic during the late pleistocene and holocene

environmental boundary conditions of cold water coral mound growth over the last 3 million years in the porcupine seabight northeast atlantic iodp expedition 307 made it for the first time possible to investigate the entire body of a cold water coral carbonate mound here we provide new insights into the long term history of challenger mound on the european continental margin off ireland this study is based on age determinations 230th u 87sr 86sr and geochemical signals mg li and ba ca measured in the scleractinian cold water coral lophelia pertusa from iodp site 1317 in the porcupine seabight the paleoceanographic reconstructions reveal that coral growth in the porcupine seabight was restricted to specific oceanographic conditions such as enhanced export of primary production and bottom water temperatures bwt between 8 10 c related to the water mass stratification of the mediterranean outflow water mow and eastern north atlantic water enaw the geochemical signals from the coral skeletons can be explained by the close interaction between cold water coral growth sea surface productivity and the surrounding water masses the boundary layer between mow and enaw enhanced sea surface productivity and the build up of a stable water mass stratification between enaw and mow caused enhanced nutrient supply at intermediate water depths and facilitated a steady mound growth between 3 0 2 1 ma with the decrease in sea surface productivity and related reduced export productivity the food supply was insufficient for rapid coral mound growth between 1 7 1 ma during the late pleistocene over the last 0 5 myr mound growth was restricted to interglacial periods during glacials the water mass boundary between enaw mow probably was below the mound summit and hence food supply was not sufficient for corals to grow

reprint of on and off the beaten track megafaunal sessile life and adriatic cascading processes abstract valuable megafaunal sessile assemblages in the southern adriatic basin present a western eastern asymmetric distribution this is particularly evident when considering cold water coral cwc communities with most diverse and abundant live corals to be found along the western side on the contrary only spotty occurrences are documented in the eastern side and at times only in a sub fossil state we hypothesize that this asymmetry might derive from differential exposure of the adriatic floor to polarized hydrological processes in such a perspective vigorous albeit a periodical flushing of deep sea bottoms at times of cascading processes could be beneficial to sessile deep sea benthic communities by reinforcing the north adriatic dense water naddw contrasting excess silting and by enhancing the trophic web although no experimental evidence has been yet produced to test this hypothesis it gains some support by the observation that cwc are flourishing in the general area of the bari canyon and adjacent bottoms flushed by dense shelf water dsw cascading while they are much less developed on the basin s opposite side unaffected by this phenomenon

sediment dynamics of a sandy contourite the sedimentary context of the darwin cold water coral mounds northern rockall trough grainsize mineralogy and current meter data from the northern rockall trough are presented in order to characterise the sandy contourite that forms the sedimentary environment of the darwin cold water coral mounds and to investigate the impact of this environment on the mound build up large clusters of small cold water coral mounds 75 m across and 5 m high have been found southwest of the wyville thomson ridge at 900 1 100 m water depth their present day sedimentary environment consists of a subtly sorted sandy contourite elongated ne sw roughly parallel to the contours critical erosional and depositional current speeds were calculated and trends in both the quartz feldspar and foraminifera fractions of the sands show a bi directional fining from bedload erosion dominated sands in the ne to suspension deposition dominated sediments in the sw and towards the s downslope this is caused by a gradual reduction in governing current speed linked to a reduction in slope gradient and by the increasing distance from the current core in the downslope direction no specific characteristics were found distinguishing the mound sediments from the surrounding sands they fit in the overall spatial pattern some mound cores show hints of a fining upward trend overall the mound build up process is interpreted as a result of sediment baffling

northeastern atlantic cold water coral reefs and climate u series age patterns obtained on reef framework forming cold water corals collected over a nearly 6000 km long continental margin sector extending from off mauritania 17 degrees n northwest africa to the southwestern barents sea 70 degrees n northeastern europe reveal strong climate influences on the geographical distribution and sustained development of these ecosystems over the past three glacial interglacial cycles framework forming cold water corals lophelia pertusa and madrepora oculata seem to have predominantly populated reefs canyons and patches in the temperate east atlantic and the mediterranean sea above 50 degrees n corals colonize reefs in the northern east atlantic primarily during warm climate periods with the biogeographic limit advancing from similar to 50 degrees n to similar to 70 degrees n we propose that north south oscillations of the biogeographic limit of reef developments are paced by ice ages and may occur synchronously with north south displacement of cold nutrient rich intermediate waters and surface productivity related to changes of the polar front

environmental and biological effects on the stable isotope composition of recent deep sea benthic foraminifera from the western mediterranean sea abstract the influence of microhabitat organic matter flux and metabolism on the stable oxygen and carbon isotope composition of live rose bengal stained and dead empty tests deep sea benthic foraminifera from the gulf of lions western mediterranean sea have been studied the total range of observed foraminiferal isotope values exceeds 1 0 for 18o and 2 2 for 13c demonstrating a wide range of coexisting disequilibria relative to 18o of equilibrium calcite 18oeq and 13c of bottom water dissolved inorganic carbon 13cdic the mean 18o values reveal strongest disequilibria for the studied epifaunal to shallow infaunal species cibicidoides pachydermus uvigerina mediterranea uvigerina peregrina while values approach equilibrium in deep infaunal species globobulimina affinis globobulimina pseudospinescens the mean 13c values decrease with increasing average living depths of the different species thus reflecting a dominant microhabitat pore water signal at the axis of the lacaze duthier canyon a minimum 13cdic pore water gradient of approximately 2 1 is assessed for the upper 6 cm of the surface sediment although live individuals of u mediterranea were found in different depth intervals their mean 13c values are consistent with calcification at an average living depth around 1 cm the deep infaunal occurrence of u mediterranea specimens suggests association with macrofaunal burrows creating a microenvironment with geochemical characteristics similar to the topmost centimeter this also explains the excellent agreement between stable isotope signals of live and dead individuals the ontogenetic enrichment in both 18o and 13c values of u mediterranea suggests a slow down of metabolic rates during test growth similar to that previously observed in planktic foraminifera enhanced organic carbon fluxes and higher proportion of resuspended terrestrial organic material at the canyon axis are reflected by 13c values of u mediterranea on average 0 58 lower than those from the open slope these results demonstrate the general applicability of the 13c signal of this species for the reconstruction of past organic matter fluxes in the mediterranean sea further studies on live specimens are needed for a more quantitative paleoceanographic approach

coccolithophore productivity and surface water dynamics in the alboran sea during the last 25kyr abstract coccolithophore productivity and surface water dynamics for the last 25 kyr in the alboran sea western mediterranean are described in a study of high resolution sedimentary records from two cores her gc t1 and ceuta10pc08 whose locations are currently characterized by different hydrographic conditions fossil coccolithophore assemblages and oxygen isotopes and alkenone and planktonic foraminifera derived sea surface temperature sst records allowed a reconstruction of the properties of the inflowing atlantic water aw which have proved to be a primary control of the variations in productivity in the neighborhood of the strait of gibraltar other local factors such as fluvial discharge wind induced and eddy induced upwelling are proposed to have influenced marine productivity in more distant areas the entrance of cold and less saline aw during the stadials associated with heinrich events 2 and 1 prevented primary productivity which increased along the last glacial maximum probably due to a greater fluvial discharge during terminations 1a and 1b the upper water column was affected by stratification although wind induced upwelling occurred locally the bolling allerod was characterized by a gradual increase in productivity and the development of the organic rich layer two phases of the younger dryas are recognized a first phase which was colder followed by a second phase which was warmer and wetter differences in productivity between both locations during these two phases can be attributed to fluvial discharge and the changing properties of the aw local hydrography such as the dynamics of the western anticyclonic gyre gained greater importance in determining productivity and its variations during the holocene which was the most productive period

genesis and morphology of cold water coral ridges in a unidirectional current regime abstract cold water coral ridges with waveform morphology are commonly observed in mound surfaces in the northeast atlantic ocean and interpreted as sediment waves overgrown by corals this work documents the first cold water coral ridges that are waveform but lack sand dune cores these coral ridges are situated at the base of the miami terrace in the straits of florida depths of 630 to 870 m they are entirely biogenic in origin and are unrelated to antecedent topography five lines of evidence based on 27 km2 of high resolution geophysical oceanographic and ground truthing data support this interpretation first the waveform coral ridges are aligned perpendicular to a southward flowing bottom current and juxtaposed to an active sand dune field devoid of corals both the coral ridges and sand dunes are asymmetric in profile with respect to the current however the ridges have their steep sides facing the current whereas the dunes exhibit a steep leeside second the coral ridge matrix consists of very fine sand to mud particles with no bedload sand transport on the ridge flanks or troughs in contrast active sand ripples superimpose the juxtaposed sand dunes indicating that coarse sand is transported via traction in this domain third bedload sand transport occurs in linear streaks at the shallowest part of the surveyed area these streaks orthogonally crosscut some coral ridges but coral colonies are not aligned along these streaks instead the bedload sand smothers the coral colonies and thereby segments the ridges fourth the sand dune and coral ridge acoustic responses are different below the dunes there is no sub bottom reflection due to energy attenuation in contrast a continuous reflection below the coral ridges proves the absence of attenuating sand cores fifth this continuous sub bottom reflection is not correlated with the coral ridge topography indicating that antecedent topography does not control the waveform morphology and spatial distribution of the ridges the differences in depositional profiles sediment dynamics and features as well as acoustic facies between the coral ridges and the juxtaposed dunes show that the coral ridges are entirely bioconstructional and not a veneer of corals covering paleo sand dunes this field of biogenic ridges at the miami terrace and the distribution of sand streaks as well as active sand dunes provide new insights how the lateral variability of current velocities and sediment transport conditions control the morphology distribution and genesis of cold water coral features

the west melilla cold water coral mounds eastern alboran sea morphological characterization and environmental context a new mound field the west melilla mounds interpreted as being cold water coral mounds has been recently unveiled along the upper slope of the mediterranean moroccan continental margin a few kilometers west of the cape tres forcas this study is based on the integration of high resolution geophysical data swath bathymetry parametric sub bottom profiler ctd casts acoustic doppler current profiler adcp rov video and seafloor sampling acquired during the topomed gassis 2011 and melcor 2012 cruises up to 103 mounds organized in two main clusters have been recognized in a depth range of 299 590 m displaying a high density of 5 mounds km2 mounds 1 48 m high above the surrounding seafloor and on average 260 m wide are actually buried by a 1 12 m thick fine grained sediment blanket seismic data suggest that the west melilla mounds grew throughout the early pleistocene holocene settling on erosive unconformities and mass movement deposits during the last glacial interglacial transition the west melilla mounds may have suffered a drastic change of the local sedimentary regime during the late holocene and unable to stand increasing depositional rates were progressively buried at the present day temperature and salinity values on the west melilla mounds suggest a plausible oceanographic setting suitable for live cwcs nonetheless more data is required to groundtruth the west melilla mounds and better constrain the interplay of sedimentary and oceanographic factors during the evolution of the west melilla mounds

proliferation and demise of deep sea corals in the mediterranean during the younger dryas abstract uranium series and radiocarbon ages are reported for deep sea corals madrepora oculata desmophyllum dianthus lophelia pertusa and caryophyllia smithii from the mediterranean sea u series dating indicates that deep sea corals have persisted in the mediterranean for over 480 000 years especially during cool interstadial periods the most prolific period of growth however appears to have occurred within the younger dryas yd period from 12 900 to 11 700 years bp followed by a short 330 years phase of post yd coral growth from 11 230 to 10 900 years bp this indicates that deep sea corals were prolific in the mediterranean not only during the return to the more glacial like conditions of the yd but also following the rapid deglaciation and transition to warmer conditions that followed the end of the yd surprisingly there is a paucity last glacial maximum lgm coral ages implying they were largely absent during this period when cold water conditions were more prevalent radiocarbon ages show that the intermediate depth waters of the mediterranean generally had 14 c compositions similar to surface waters indicating that these waters were extremely well ventilated the only exception is a narrow period in the yd 12 500 100 years bp when several samples of lophelia pertusa from the ionian sea had 14 c values falling significantly below the marine curve using a refined approach isolation ages isol of 300 years to 500 years are estimated for these intermediate 800 1000 m depth waters relative to surface marine waters indicating a reduction or absence of deep water formation in the ionian and adjacent adriatic seas during the yd contrary to previous findings we find no evidence for widespread intrusion of low 14 c atlantic waters into the mediterranean prolific growth of deep sea corals in the mediterranean ended abruptly at 10 900 years bp with many of the coral bearing mounds on the continental slopes being draped in a thin veneer of mud their demise is attributed to a number of factors including the direct loss of habitat due to high sedimentation that accompanied glacial meltwater pulses together with rising temperatures that would have finally pervaded the deeper water of the mediterranean following the onset of holocene warming

the importance of the permanent thermocline to the cold water coral carbonate mound distribution in the ne atlantic abstract a prominent feature of the nw european continental slope is the presence of numerous cold water coral carbonate mounds that are clustered in a number of provinces these provinces occupy a relatively narrow depth range along the continental slope 95 of all coral carbonate mounds identified on the irish seabed have their mound bases between 500 and 1000 m water depths with a peak in distribution at 650 m water depth the distribution in mound base depths is skewed with a tail extending from the maximum at 650 m to deeper depths this distribution brackets the depth of the permanent thermocline in the ne atlantic 600 1000 m formed below the base of the winter mixed layer it is shown that the permanent thermocline is associated with the strongest residual near seabed current flow with typical residual current speeds up to 2 3 times larger at the thermocline depth compared to other depths the strong vertical density gradient associated with the permanent thermocline together with the steep continental slope at those depths also enhances the energy of certain periodic motions such as internal waves and baroclinic tidal currents these dynamic conditions favour mound growth through the promotion of significant along slope sediment transport and also provide large across slope sediment movement and organic matter fluxes the stability of the thermocline structure is likely the key in providing favourable conditions over long time scales that allow mound growth through sediment baffling processes

changes in the advection of antarctic intermediate water to the northern chilean coast during the last 970 kyr 1 the antarctic intermediate water aaiw is a key player in global scale oceanic overturning processes and an important conduit for heat fresh water and carbon transport the aaiw past variability is poorly understood mainly due to the lack of sedimentary archives at intermediate water depths we present records of benthic stable isotopes from sediments retrieved with the seafloor drill rig marum mebo at 956 m water depth off northern chile geob15016 27 29 48 s 71 07 58 w that extend back to 970 ka the sediments at this site are presently deposited at the boundary between aaiw and pacific deep water pdw for previous peak interglacials our results reveal similar benthic 13c values at site geob15016 and of a newly generated stack of benthic 13c from various deep pacific cores representing the average pdw this suggests unlike today the absence of aaiw at the site and the presence of nearly pure pdw in contrast more positive 13c values at site geob15016 compared to the stack imply a considerable aaiw contribution during cold phases of interglacials and especially during glacials besides we used three short sediment cores to reconstruct benthic 13c values from the aaiw core during the last glacial and found a 13c signature similar to today s assuming that this was the case also for the past 970 kyr we demonstrate that sea level changes and latitudinal migrations of the aaiw formation site can only account for about 50 of the full range of past 13c increases at site geob15016 during cold periods other processes that could explain the remaining of the positive 13c anomalies are increases in glacial aaiw production and or deeper convection of the aaiw with respect to preceding interglacials

large deep water coral banks in the porcupine basin southwest of ireland the porcupine basin southwest of ireland was one of the earliest sites from where the deep water corals lophelia sp and madrepora sp were recovered these deep water corals have since been found all along the atlantic margins of europe in water depths ranging from 50 to more than 2000 m recent geophysical studies have demonstrated the mound building potential of deep water corals available data indicate that three major provinces of coral bank occurrences can be identified in the porcupine basin 1 high relief surface mounds which have a dimension of 1 by 5 km and a height up to 200 m hovland mounds flanked to the north by 2 a swarm of buried mounds somewhat smaller up to 90 m and with more irregular shapes than those recognised in area 1 magellan mounds and 3 outcropping or buried conical mounds single or in elongated clusters up to 150 m high occurring on the southeastern slope of the basin belgica mounds as far as can be inferred from shallow cores the surface lithology predominantly consists of an upper layer rich in foraminiferal sand and terrigenous silty clay with intercalations of biogenic rubble the banks host a remarkable number of colonies of living and dead lophelia pertusa and madrepora oculata the living and dead assemblages are underlain by a significant layer of coral debris in a muddy matrix deep water coral debris together with a living association of the same species covers the surface of the belgica and hovland mounds which may suggest that these corals have played a significant role in the development of the mound structures the capacity for mound formation by scleractinian corals in the aphotic zone has been known for some time examples are found at different locations along the shelves and the continental margins of the north atlantic the role of the corals in these deep water build ups is still a point of debate though the genesis and initial control of mound settings in this basin might be related to hydrocarbon seeps it appears that the major development of the porcupine coral banks in recent geological times has most likely been controlled by oceanic circulation and dynamics in water masses and nutrient supply

paleoproductivity variations related to climatic conditions in the alboran sea western mediterranean during the last glacial interglacial transition the diatom record the present study addresses the analysis of changes in marine primary productivity derived from climatic variability over the last 30 000 yr the study area is the alboran sea this is the westernmost basin of the mediterranean sea and was a very sensitive area to changes in sea levels and atmospheric configuration during the last glacial interglacial transition we report the results from four sediment cores recovered in both the western and eastern alboran basins this allowed us to monitor the w e evolution of the hydrological structures the study is mainly based on the diatom record although total organic carbon toc isotopes and uk 0 37 sst were also used to gain further information paleoceanographic conditions favoured high paleoproductivity rates during the last glacial maximum although this occurred at termination 1a and during the younger dryas event yd increasing towards the easternmost sites during these periods meteorological conditions with increased westerlies intensified the flow to the east driving an eastward migration of the western anticyclonic gyre a possible displacement of the north alboran upwelling system is also considered the major component of the diatom assemblage during the yd are the resting spores of leptocylindrus danicus which suggest the presence of cooler and less saline surface waters the opposite behaviour between planktonic and benthic proxies in addition to the high toc values allows us to infer a phase of reduced deep water renewal between 16 5 and 9 cal ky bp fresh water diatoms and opal phytoliths were used as indicators of aridity and humid land conditions respectively during the glacial period and until 14 cal ky bp we observed a gradual climatic deterioration accompanied by a loss of grass belts climatic conditions were warmer and moister during the bolling allerod while the yd was dry the re establishment of vegetation belts and replenishment of lakes was observed at 8 cal ky bp q 2001 elsevier science b v all rights reserved

formal subdivision of the holocene series epoch a discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommission on quaternary stratigraphy international commission on stratigraphy this discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommision on quaternary stratigraphy sqs of the international commission on stratigraphy ics considers the prospects for a formal subdivision of the holocene series epoch although previous attempts to subdivide the holocene have proved inconclusive recent developments in quaternary stratigraphy notably the definition of the pleistocene holocene boundary and the emergence of formal subdivisions of the pleistocene series epoch mean that it may be timely to revisit this matter the quaternary literature reveals a widespread but variable informal usage of a tripartite division of the holocene early middle or mid and late and we argue that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology we propose an early middle holocene boundary at 8200 a bp and a middle late holocene boundary at 4200 a bp each of which is linked to a global stratotype section and point gssp should the proposal find a broad measure of support from the quaternary community a submission will be made to the international union of geological sciences iugs via the sqs and the ics for formal ratification of this subdivision of the holocene series epoch copyright 2012 john wiley sons ltd

structure and development of giant carbonate mounds at the sw and se rockall trough margins ne atlantic ocean abstract high resolution seismic reflection profiling carried out in 1997 1999 showed that giant carbonate mounds occur between 500 and 1200 m water depth along both the se and sw margins of rockall trough the mounds rise 5 300 m above the surrounding seafloor and have diameters at their bases of up to 5 km buried mounds at relatively shallow depths below the seafloor are also found both individual and complex clusters of mounds can be recognized smaller and individual sometimes buried mounds are found at the upper slope on the sw rockall trough margin higher steeper and individual mounds are found deeper downslope 900 1100 m at the middle slope the mounds merge into a complex structure and form complex clusters with a very irregular upper surface and an apparent lack of internal reflectors 600 1000 m depth initial results of high resolution 3d seismic profiling at 30 m line spacing in august 2000 in two boxes of 750 m 14 5 km covering a small central part of the sw rockall trough mound area indicate two stages of mound development here the latest probably of pliocene holocene age this age based on the presence of a regionally recognizable unconformity below the mounds is also assumed for the mounds of the se rockall trough porcupine bank margin

a 130 000 year record of levantine intermediate water flow variability in the corsica trough western mediterranean sea abstract sortable silt particle size data and stable isotope analyses from the corsica trough western mediterranean sea provide a continuous palaeoceanographic record of the inflow ventilation and vertical fluctuations of the levantine intermediate water liw in the northern tyrrhenian sea for the last 130 000 years the results presented herein reveal that climate changes drive the mediterranean intermediate circulation on milankovitch to millennial time scales intensified intermediate inflow and ventilation in the corsica trough occurred throughout the last glacial interval with a cold faster warm slower pattern existing between the dansgaard oeschger climatic oscillations including heinrich events and the liw variability by contrast a weak intermediate ventilation characterised the holocene and the last interglacial period especially during insolation maxima and the sapropel deposition in the eastern mediterranean this variability probably reflects the changes of the eastern mediterranean net evaporation as well as the propagation to the western mediterranean of the profound hydrographic adjustments of the levantine sea and adjacent areas to climate forcing the implications for the formation and ventilation of the western mediterranean deep water wmdw in the northwestern mediterranean basin as well as for mediterranean atlantic exchange through the strait of gibraltar are discussed

growth and demise of cold water coral ecosystems on mud volcanoes in the west alboran sea the messages from the planktonic and benthic foraminifera the dhaka and maya mud volcanoes mvs located in the mud diapir province in the western alboran basin along the moroccan coasts were cored during the ttr 17 leg 1 cruise cores were taken on the top of the volcanoes at a water depth of 370 m on the dhaka mv core ttr17 ms411g and at 410 m water depth on the maya mv core ttr17 ms419g respectively on both mud volcanoes the extruded mud breccia provides the nucleation point for the colonization and development of cold water corals and associated ecosystems two phases of cold water coral growth are observed 1 between slightly older than 4175 62 years bp and around 2230 59 years bp at dhaka and 2 between slightly older than 15583 185 years bp and around 7613 38 years bp at maya mv on the top of the maya mv only a small patch reef and or isolated corals proliferated whereas a more extended patch reef colonized the top of the dhaka mv at both sites the cold water coral developmentwas triggered by the availability of a suitable substrate for initial coral settling provided either as a firm ground or as single clasts subsequently coral growth was supported by enhanced nutrient flux possibly related to upwelling and or strong currents during the intervals of coral growth planktonic foraminiferal assemblages were dominated by neogloboquadrina incompta the decline of coral ecosystems on the mud volcanoes is accompanied at surface by a shift fromthe n incompta dominated assemblage to a globorotalia inflata dominated assemblage possibly reflecting more oligotrophic conditions this shift is coeval to the passage from wet to arid conditions at the end of the african humid period at mayamv it is interpreted as an effect of an early human impact on a fragile environment which was already stressed by desiccation at the time of the development of complex human society along the mediterranean coasts at dhaka mv

environmental changes and growth history of a cold water carbonate mound propeller mound porcupine seabight on and off mound sediment cores from propeller mound hovland mound province porcupine seabight were analysed to understand better the evolution of a carbonate mound the evaluation of benthic foraminiferal assemblages from the off mound position helps to determine the changes of the environmental controls on propeller mound in glacial and interglacial times two different assemblages describe the holocene and marine isotope stage mis 2 and late mis 3 31 kyr bp the different assemblages are related to changes in oceanographic conditions surface productivity and the waxing and waning of the british irish ice sheet biis during the last glacial stages the interglacial assemblage is related to a higher supply of organic material and stronger current intensities in water depth of recent coral growth during the last glaciation the benthic faunas showed high abundances of cassidulinid species implying cold bottom waters and a reduced availability of organic matter high sedimentation rates and the domination of elphidium excavatum point to shelf erosion related to sea level lowering 50 m and the progradation of the biis onto the shelf a different assemblage described for the on mound core is dominated by discanomalina coronata gavelinopsis translucens planulina ariminensis cibicides lobatulus and to a lower degree by hyrrokkin sarcophaga these species are only found or show significantly higher relative abundances in on mound samples and their maximum contribution in the lower part of the record indicates a higher coral growth density on propeller mound in an earlier period they are less abundant during the holocene however this dataset portrays the boundary conditions of the habitable range for the cold water coral lophelia pertusa which dominates the deep water reefal ecosystem on the upper flanks of propeller mound the growth of this ecosystem occurs during interglacial and interstadial periods whereas a retreat of corals is documented in the absence of glacial sediments on mound glacial conditions with cold intermediate waters a weak current regime and high sedimentation rates provide an unfavourable environmental setting for lophelia corals to grow a late pleistocene decrease is observed in the mound growth for propeller mound which might face its complete burial in the future as it already happened to the buried mounds of the magellan mound province further north

variability of the western mediterranean sea surface temperature during the last 25 000 years and its connection with the northern hemisphere climatic changes sea surface temperature sst profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a w e latitudinal transect encompassing the gulf of cadiz atlantic ocean the alboran sea and the southern tyrrhenian sea western mediterranean the results document the sensitivity of the mediterranean region to the short climatic changes of the north atlantic ocean particularly those involving the latitudinal position of the polar front the amplitude of the sst oscillations increases toward the tyrrhenian sea indicating an amplification effect of the atlantic signal by the climatic regime of the mediterranean region all studied cores show a shorter cooling phase 700 years for the younger dryas yd than that observed in the north atlantic region 1200 years this time diachroneity is related to an intra yd climatic change documented in the european continent minor oscillations in the southward displacement of the north atlantic polar front may also have driven this early warming in the studied area during the holocene a regional diachroneity propagating west to east is observed for the sst maxima 11 5 10 2 kyr b p in the gulf of cadiz 10 9 kyr b p in the alboran sea and 8 9 8 4 kyr b p in the thyrrenian sea a general cooling trend from these sst maxima to present day is observed during this stage which is marked by short cooling oscillations with a periodicity of 730 40 years and its harmonics

synchronisation of palaeoenvironmental events in the north atlantic region during the last termination a revised protocol recommended by the intimate group abstract the north atlantic intimate group of the inqua palaeoclimate commission has previously recommended an event stratigraphy approach for the synchronisation of records of the last termination using the greenland grip isotopic record as the regional stratotype and intcal98 for the calibration of radiocarbon dates lowe j j hoek w intimate group 2001 inter regional correlation of palaeoclimatic records for the last glacial interglacial transition a protocol for improved precision recommended by the intimate project group quaternary science reviews 20 1175 1187 here we present a revised protocol for time stratigraphic correlation in the north atlantic region over a more extended time period 30 8 ka this employs the new ngrip isotopic record and associated greenland ice core chronology 2005 gicc05 as the regional stratotype intcal04 for the calibration of radiocarbon dates bayesian based statistical procedures for the construction of age models and tephrochronology to validate correlations between regional site records

crustal stabilization through the processes of ridge subduction examples from the chugach metamorphic complex southern alaska a tectonic process commonly overlooked in the growth and formation of continental crust is ridge subduction this process can stabilize a forearc accretionary complex through high grade metamorphism anatexis pluton emplacement and underplating of mafic rock an excellent example of the process is in the chugach metamorphic complex cmc southern alaska formed as a result of late cretaceous to paleogene subduction of the kula farallon or kula resurrection ridge ridge subduction subjected the trench fill turbidites of the accretionary prism to greenschist to amphibolite grade metamorphism under high temperature low pressure conditions converting them to a gneissic basement in the core of the cmc and regional near trench plutonism in addition to high grade metamorphism and near trench plutonism the cmc experienced three distinct phases of deformation associated with triple junction position in the process of becoming stabilized continental crust 1 accretionary prism related compression and metamorphism 2 eastward migration of the triple junction and associated ridge subduction producing orogen parallel extension peak metamorphism and mafic underplating and 3 dextral transpression following the migrating triple junction this combination of progressive deformation and tectonic phases produces continental crust effectively becoming a stable tectonic backstop by the time of neogene yakutat terrane collision the present day locus of deformation

cold water coral carbonate mounds as unique palaeo archives the plio pleistocene challenger mound record ne atlantic through the interplay of a stabilising cold water coral framework and a dynamic sedimentary environment cold water coral carbonate mounds create distinctive centres of bio geological accumulation in often complex continental margin settings the iodp expedition 307 drilling of the challenger mound eastern porcupine seabight ne atlantic not only retrieved the first complete developmental history of a coral carbonate mound it also exposed a unique early pleistocene sedimentary sequence of exceptional resolution along the mid latitudinal ne atlantic margin in this study a comprehensive assessment of the challenger mound as an archive of quaternary palaeo environmental change and long term coral carbonate mound development is presented new and existing environmental proxy records including clay mineralogy planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts planktonic foraminifer oxygen isotopes and siliciclastic particle size are thereby discussed within a refined chronostratigraphic and climatic context overall the development of the challenger mound shows a strong affinity to the plio pleistocene evolution of the northern hemisphere climate system albeit not being completely in phase with it the two major oceanographic and climatic transitions of the plio pleistocene the late pliocene early pleistocene intensification of continental ice sheet development and the mid pleistocene transition to the more extremely variable and more extensively glaciated late quaternary mark two major thresholds in challenger mound development its late pliocene 2 74 ma origin and its middle late pleistocene to recent decline distinct surface water perturbations i e water mass polar front migrations productivity changes melt water pulses are identified throughout the sequence which can be linked to the intensity and extent of ice development on the nearby british irish isles since the earliest pleistocene glaciation induced shifts in surface water primary productivity are thereby proposed to fundamentally control cold water coral growth which in turn influences on mound sediment accumulation and hence coral carbonate mound development throughout the pleistocene as local factors such as proximal ice sheet dynamics and on mound changes in cold water coral density significantly affected the development of the challenger mound they can potentially explain the nature of its palaeo record and its offsets with the periodicities of global climate variability on the other hand owing to this unique setting a regionally exceptional high resolution palaeo record of early pleistocene ca 2 6 to 2 1 ma environmental change including early british irish ice sheet development broadly in phase with the 41 ka paced global climate system is preserved in the lower challenger mound all in all the challenger mound record highlights the wider relevance of coral carbonate mound archives and their potential to capture unique records from dynamic continental margin environments

variations in the structure of the anticyclonic gyres found in the alboran sea historical satellite aircraft and in situ data have shown that two anticyclonic gyres the western and eastern alboran gyres are major ocean features of the alboran sea an examination of several years of satellite imagery indicates that large variations in the surface expression of these two gyres occur and that on occasion one or the other gyre disappears the disappearance of both gyres at the same time was not seen the initial disappearance of either gyre occurs on a time scale of a week to 2 weeks whereas the return may take from 3 weeks to 2 months various forcing mechanisms i e winds mass flux inflow through the straits of gibraltar and sicily and or density have been used in numerical ocean circulation models to study the dynamics of the western mediterranean sea various model results show relationships similar to those shown by the satellite imagery however no single forcing mechanism has been positively identified as the source of the disappearances and the events may be a result of a combination of forcing mechanisms

cold water coral mounds in the southern alboran sea western mediterranean sea internal waves as an important driver for mound formation since the last deglaciation abstract cold water corals cwcs are widely distributed in the entire alboran sea western mediterranean sea but only along the moroccan margin they have formed numerous coral mounds which are constrained to the west and the east melilla cwc mound provinces wmcp and emcp while information already exists about the most recent development of the coral mounds in the emcp the temporal evolution of the mounds in the wmcp was unknown up to the present in this study we present for the first time cwc ages obtained from four sediment cores collected from different mounds of the wmcp which allowed to decipher their development since the last deglaciation our results revealed two pronounced periods of coral mound formation the average mound aggradation rates were of 75 176 cm kyr 1 during the bolling allerod interstadial and the early holocene only temporarily interrupted during the younger dryas when aggradation rates decreased to

seafloor characterization and backscatter variability of the almeria margin alboran sea sw mediterranean based on high resolution acoustic data abstract an acoustic study of the almeria margin eastern alboran sea sw mediterranean was carried out by means of an integrated dataset comprising deep towed tobi sidescan sonar swath bathymetry topas high resolution seismics and sediment gravity cores the almeria margin is a complex system dominated by volcanic and tectonic features shaped by recent sedimentary processes in which a regional hemipelagic sedimentation is intercalated by sporadic gravitative events the aim of this work is twofold the first objective is to recognize the sedimentary and tectonic features that shape the almeria margin the main morpho sedimentary and morpho structural elements observed are the almeria canyon channel turbidite system the dalias tributary valley system landslides active faults and folds and volcanic banks the second aim is to explore and quantify the surface and subsurface seafloor parameters that characterize the backscatter of the study area sedimentary geomorphological and biological elements that play a role in the acoustic signature of the almeria margin were detected nevertheless it should be noted that seafloor acoustic backscatter is also affected by geometrical and instrumental factors despite the wide variability of the environments studied a low average acoustic backscatter reflects a diffused draping of hemipelagic sedimentation in the area higher backscatter values were observed at the top of some volcanic banks along the almeria canyon and in the shallower sector of the dalias tributary valley system the influence of subseafloor properties in the acoustic signature of the area was revealed by backscatter grain size correlations which were carried out for different depth intervals in sediment cores collected in the almeria turbidite system a poor relationship was found between backscatter and superficial silty sediments of the area whereas a higher correlation resulted in the upper 50 cm the presence of subsurface turbidites in the cores associated with the higher backscatter values suggests volume interface scattering of these sandy layers as a controlling factor of the acoustic signature obtained in the almeria margin on the other hand in rough settings such as the ones observed in the dalias tributary valley system topographic relief of up to 1 1 5 m strongly interacted with the tobi acoustic pulse this suggests that large scale roughness is an additional parameter that characterizes the acoustic strength of the area extremely high reflective patches distributed along some of the volcanic banks chella and pollux banks for depths ranging from 230 to 470 m coincide with areas where carbonate cold water coral mounds develop in the tobi images coral facies reach the maximum value of acoustic backscatter which is probably related to the rough morphology of coral ecosystems the position of coral mounds in the banks suggests that the occurrence of strong bottom currents and reduced sedimentary inputs are environmental factors that favour their settling and development in the almeria margin

benthic foraminiferal δ13c and accumulation rates of organic carbon uvigerina peregrina group and cibicidoides wuellerstorfi the glacial to interglacial 13c records of the benthic foraminifera cibicidoides wuellerstorfi and the uvigerina peregrina group from deep sea cores cannot be adjusted by a generally valid constant the 13c values of the u peregrina group largely correlate with the accumulation rates of organic carbon suggesting a local habitat effect those of c wuellerstorfi vary independently with respect to the carbon flux and record fluctuations in the 13c of the ambient bottom water isotopic composition

cold water coral growth in the alboran sea related to high productivity during the late pleistocene and holocene abstract cold water corals are common along the moroccan continental margin off melilla in the alboran sea western mediterranean sea where they colonise and largely cover mound and ridge structures radiocarbon ages of the reef forming coral species lophelia pertusa and madrepora oculata sampled from those structures reveal that they were prolific in this area during the last glacial interglacial transition with pronounced growth periods covering the bolling allerod interstadial 13 5 12 8 ka bp and the early holocene 11 3 9 8 ka bp their proliferation during these periods is expressed in vertical accumulation rates for an individual coral ridge of 266 419 cm ka 1 that consists of coral fragments embedded in a hemipelagic sediment matrix following a period of coral absence as noted in the records cold water corals re colonised the area during the mid holocene 5 4 ka bp and underwater photographs indicate that corals currently thrive there it appears that periods of sustained cold water coral growth in the melilla coral province were closely linked to phases of high marine productivity the increased productivity was related to the deglacial formation of the most recent organic rich layer in the western mediterranean sea and to the development of modern circulation patterns in the alboran sea