changes in coral reef structure through the miocene in the mediterranean province adaptive versus environmental influence well documented mediterranean examples of miocene carbonate platforms with complete exposures from shallow water to basinal facies provide evidence for temporal changes in reef building capacity of zooxanthellate corals in pre late tortonian platforms small coralgal patches and mounds occur from platform top to the toe of slope but they did not build to sea level in contrast barrier reefs with unequivocal reef crest structures that reached sea level are documented in late tortonian early messinian platforms we suggest that a change in both calcification rates and bathymetric zonation was the result of coevolution of corals and symbiodinium zooxanthellae coeval to global cooling and at least at a regional scale a geochemical change that supported widespread aragonite precipitation through the late miocene

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

atmospheric pco2 since 60 ma from records of seawater ph calcium and primary carbonate mineralogy a 60 m y record of atmospheric p co2 has been refined from knowledge of 1 secular changes in the major ion composition of seawater particularly ca and mg and 2 oscillations in the mineralogy of primary oceanic carbonate sediments both factors have had a significant impact on the chemistry of the ocean carbonate buffer system calculated atmospheric p co2 oscillated between values of 100 300 ppm and to maxima of 1200 2500 ppm from 60 to 40 ma and varied between 100 and 300 ppm from 25 ma to the present the refined p co2 values are significantly lower than previous estimates made from seawater ph data where total dissolved inorganic carbon was assumed constant and more in line with modeling and stomatal index estimations of atmospheric p co2 for the tertiary

the evolution of mid paleocene early eocene coral communities how to survive during rapid global warming abstract today diverse communities of zooxanthellate corals thrive but do not build reef under a wide range of environmental conditions in these settings they inhabit natural bottom communities sometimes forming patch reefs coral carpets and knobs episodes in the fossil record characterized by limited coral reef development but widespread occurrence of coral bearing carbonates may represent the fossil analogs of these non reef building zooxanthellate coral communities if so the study of these corals could have valuable implications for paleoenvironmental reconstructions here we focus on the evolution of early paleogene corals as a fossil example of coral communities mainly composed by zooxanthellate corals or likely zooxanthellate commonly occurring within carbonate biofacies and with relatively high diversity but with a limited bioconstructional potential as testified by the reduced record of coral reefs we correlate changes of bioconstructional potential and community compositions of these fossil corals with the main ecological environmental conditions at that time the early paleogene greenhouse climate was characterized by relatively short pulses of warming with the most prominent occurring at the paleocene eocene boundary petm event associated with high weathering rates nutrient fluxes and pco 2 levels a synthesis of coral occurrences integrated with our data from the adriatic carbonate platform sw slovenia and the minervois region sw france provides evidence for temporal changes in the reef building capacity of corals associated with a shift in community composition toward forms adapted to tolerate deteriorating sea water conditions during the middle paleocene coral algal patch reefs and barrier reefs occurred from shallow water settings locally with reef crest structures a first shift can be traced from middle paleocene to late paleocene with small coral algal patch reefs and coral bearing mounds development in shallow to intermediate water depths in these mounds corals were highly subordinated as bioconstructors to other groups tolerant to higher levels of trophic resources calcareous red algae encrusting foraminifera microbes and sponges a second shift occurred at the onset of the early eocene with a further reduction of coral framework building capacity these coral communities mainly formed knobs in shallow water turbid settings associated with abundant foraminiferal deposits we suggest that environmental conditions other than high temperature determined a combination of interrelated stressors that limited the coral reef construction a continuous enhancement of sediment load nutrients combined with geochemical changes of ocean waters likely displaced corals as the main bioconstructors during the late paleocene early eocene times nonetheless these conditions did not affect the capacity of some corals to colonize the substrate maintain biodiversity and act as locally important carbonate sediment producers suggesting broad environmental tolerance limits of various species of corals the implications of this study include clues as to how both ancient and modern zooxanthellate corals could respond to changing climate

marked decline in atmospheric carbon dioxide concentrations during the paleogene the relation between the partial pressure of atmospheric carbon dioxide pco2 and paleogene climate is poorly resolved we used stable carbon isotopic values of di unsaturated alkenones extracted from deep sea cores to reconstruct pco2 from the middle eocene to the late oligocene approximately 45 to 25 million years ago our results demonstrate that pco2 ranged between 1000 to 1500 parts per million by volume in the middle to late eocene then decreased in several steps during the oligocene and reached modern levels by the latest oligocene the fall in pco2 likely allowed for a critical expansion of ice sheets on antarctica and promoted conditions that forced the onset of terrestrial c4 photosynthesis

similarities between planktonic and larger foraminiferal evolutionary trends through paleogene paleoceanographic changes abstract the paleogene evolutionary records of planktonic foraminifera and larger benthic foraminifera show parallel patterns in development that may in part reflect changes in nutrient flux to surface waters following the terminal cretaceous extinctions faunas were dominated by a few cosmopolitan opportunistic species more specialized k strategists in both groups diversified during the paleocene dominating into the early eocene consistent with he globally mild climatic regime and probable limited rates of nutrient flux to surface waters high latitude cooling intensified in the middle eocene promoting diversification of less specialized taxa characteristic of cooler and deeper waters higher latitudes meridional upwelling zones and boundary currents geographic ranges of warm water taxa diminished and fragmented yet many species survived thus global diversities during the middle eocene were the highest in the cenozoic as cooling and increased rates of nutrient flux further intensified in the late eocene extinction rates of warm water planktonic and larger benthic species exceeded origination rates of cooler water and less specialized forms so diversity dropped to intermediate levels where it remained through the late eocene and oligocene previous observations that planktonic foraminiferal faunas dominated by warm water taxa are often replaced by cool water faunas even though oxygen isotopes only recorded relatively minor cooling can be reconciled by the explanation that the biotic communities responded to changes in trophic resources and euphotic habitats that accompany the temperature reduction as well as to temperature change itself

paleocene coralgal reefs of the western pyrenean basin northern spain new evidence supporting an earliest paleogene recovery of reefal ecosystems abstract the rate of recovery of photic reefal ecosystems after the cretaceous tertiary crisis is controversial most reports from earlier authors concluded that paleogene reef systems did not completely recover from that crisis at least until oligocene miocene times several other authors however have pointed out that such conclusion was biased by poor preservation and or inaccessibility of many early paleogene successions and that the recovery of reefs might have been a faster process the latter possibility is here strongly supported with data from the pyrenean basin where paleocene shallow water carbonate deposits are thickly developed and outcrop widely five growth phases of reef development have been recognized and age dated with calcareous nannofossils which together define a complete sequence of expansion reduction of reef ecosystems during the paleocene epoch reef growth phase 1 early danian lower middle np3 calcareous nannofossil zone the initial step of that sequence demonstrates that coral dominated reef systems came back into existence less than 2 ma after the k t boundary a comparatively short time considering the magnitude of the end cretaceous biological crisis the climax of the sequence is recorded by growth phase 3 late danian np4 zone when a thick barrier reef complex was developed which was at least 200 km in length but probably much larger and made up by a well diversified coralgal assemblage reef growth phases 4 and 5 early and middle thanetian np6 to np8 zones were characterized by low relief reef banks dominated by encrusting calcareous algae and had less well diversified coral assemblages features that point to a deterioration of environmental conditions tentatively interpreted in terms of a climatic cooling reef bioconstruction almost disappeared in the pyrenean basin during late thanetian times although in all likelihood this is a regional effect of no evolutionary relevance the new data suggest that the cenozoic recovery of reefs was rapid but punctuated with a phase of important reef expansion already in the late danian

impact of carbonate producing biota on platform architecture insights from miocene examples of the mediterranean region abstract different types of carbonate platforms formed in the mediterranean during the miocene low angle homoclinal types of ramp distally steepened ramps flat topped platforms and reef rimmed shelves the critical differences between these platforms result from differences in the capacities of the carbonate systems to accumulate sediments above hydrodynamic base level ecologically controlled accommodation the various depositional profiles and facies belt distributions resulted from the interplay between different sediment production and redistribution processes and the internal architectures resulted from the response of each type of platform to changes in accommodation heterogeneities driven by high frequency sea level cycles are maximized in platforms ruled by shallow water euphotic framework dominated production and minimized in low angle ramps where sediment resulted from aphotic and oligophotic carbonate production in the mediterranean region there is no direct relationship between type of platform and global temperature as shown by the coeval occurrence of different platforms in similar latitudinal settings although temperature is a key limiting factor other paleoceanographic factors such as trophic resources may have also been along with biological evolution important factors influencing different types of carbonate producing biotas

the ainsa fold and thrust oblique zone of the central pyrenees kinematics of a curved contractional system from paleomagnetic and structural data this work was funded by the project intectosal cgl2010 21968 c02 01 and by the grup de recerca de geodinamica i analisi de conques 2009sgr1198 secretaria d universitat i recerca del departament d economia i coneixement de la generalitat de catalunya josep poblet acknowledges financial support by research projects geociencias en iberia estudios integrados de topografia y evolucion 4d topo iberia csd2006 041 and desarrollo de fracturas y venas asociadas al plegamiento fraveple cgl2011 23628 funded by spanish ministries

nearshore temperate carbonate depositional systems lower tortonian agua amarga basin southern spain implications for carbonate sequence stratigraphy abstract the bryozoan rich lower tortonian carbonates of the agua amarga basin in southern spain province of almeria provide an example of sediments formed in a nearshore non tropical depositional setting based on data derived from logging of sections and from field mapping these lower tortonian carbonates form a depositional sequence which is subdivided into several depositional systems a lowstand systems tract which consists of volcaniclastic fan deltas and washover deposits formed on the leeward side of a basement shoal which delimited the basin towards the south a transgressive systems tract which is characterised by a landward encroachment of deposits is represented by submarine bars and dune deposits a highstand systems tract consists of progradational beach deposits owing to strong reworking and re distribution of the particles by currents and waves microfacies differentiation of the deposits in poor these tortonian non tropical carbonates display a style of deposition similar to siliciclastics suggesting that sequence stratigraphic concepts derived from tropical carbonates do not apply to non tropical carbonates

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

paleobiogeography of scleractinian reef corals changing patterns during the oligocene miocene climatic transition in the mediterranean abstract during the oligocene miocene greenhouse to icehouse climatic transition the biogeography of reef corals or zooxanthellate like scleractinian corals was gradually changing from a pan tropical tethyan province in the eocene to three reef coral provinces of the western atlantic caribbean indo pacific and mediterranean our reefcoral database encompasses updated and homogenized data on paleoenvironmental and systematics of scleractinian corals occurring in the oligocene and miocene outcrops from circum mediterranean regions provided by most of relatively recently published data in the literature and by the study of published and unpublished collections of coral specimens from the same area including the important collections housed at the mnhn paris and our own collections as there is no validated direct criterion for the identification of the coral zooxanthellate symbiosis in the fossil record and considering the difficulty to use the biogeochemical approaches in the context of this study the subjectivity of the morphological criteria and the relative recent age of the fossil corals we are dealing with a uniformitarian approach has been used for inferring the symbiotic status of scleractinian genera in reefcoral among the 158 genera included in our database 93 can be considered as zooxanthellate and 10 have a doubtful zooxanthellate status this relatively exhaustive database was used to reconstruct the temporal and spatial distribution of scleractinian corals in the mediterranean during the oligocene miocene time in order to discuss the interplaying effects of the global cooling at that time the re organization of the tethyan realm resulting from the african arabian and eurasian plate collision and the emergence of the alpine chains driving the gradual northward movement of the whole region outside the tropical subtropical belt it is shown that the structure of the mediterranean z coral oligocene miocene paleobiodiversity was characterized by many geographically restricted genera with a moderate to short stratigraphical range and a few long ranging widespread genera a major consequence of this structure is that the extinction pattern has proceeded through the preferential extinction of rare occurrence genera through time the potential rapid long distance dispersal of most coral larvae compared to the size of the oligocene miocene mediterranean explains why no biogeographical subprovinces can be distinguished for the z coral fauna on a local scale ecological processes tend to sort coral taxa by limiting z coral development to geographically restricted and discontinuous areas this accounts for the large amount of geographically restricted taxa forming the mediterranean coral fauna the interaction of plate tectonics alpine orogenesis and climate at local to subregional scales exerts strong controls over the spatio temporal distribution of z coral assemblages within the circum mediterranean realm in particular we suggest that the richness and composition of the eastern atlantic coral fauna are indirectly related to the opening and closure of the eastern seaway connection with the indian ocean which controlled the e w circulation of surface waters and hence the westwards dispersal of pelagic larvae at the scale of the whole region the gradual regional climatic change produced by the northwards migration of the entire area superimposed on the global cooling appears in large part responsible for the extinction pattern of z corals through time in the mediterranean biogeographical province

heterozoan carbonates in oligotrophic tropical waters the attard member of the lower coralline limestone formation upper oligocene malta abstract photozoan and heterozoan skeletal assemblages are controlled by their trophic requirements i e light based photosynthesis versus other sources and temperature photozoan associations tend to dominate tropical and subtropical waters whereas heterozoan carbonate systems tend to occur in cooler waters and in localised areas that are affected by nutrient rich upwelling or terrestrial runoff because of the wide climatic spectrum in which heterozoan carbonates are found their interpretation is often problematic we present a high resolution analysis of the attard member of the lower coralline limestone formation upper oligocene malta the biotic associations and palaeolatitudinal reconstructions suggest that carbonate sedimentation took place in tropical waters under oligotrophic conditions an important factor controlling the spread of heterozoan assemblages in the late oligocene of malta seems to be related to the palaeoecology and evolution of zooxanthellate the limited capacity of corals to thrive in high light conditions and to form a wave resistant reef promoted the diffusion of heterozoan assemblages

record of climatic change in neritic carbonates turnover in biogenic associations and depositional modes late miocene southern spain in order to evaluate the geological record of climatic change in neritic carbonates we studied late miocene rock outcrops in southern spain six episodes of reef growth are documented burdigalian to messinian in neogene basins of the betic cordillera which were located close to the margin of the global reef belt the reefs are characterized by various zooxanthellate corals which decrease in diversity with time andhalimeda the youngest reefs of the latest messinian are characterized by the dominance of the genusporites late miocene coral reefs and reef rimmed platforms alternate over time with non reefal carbonate ramps characterized by skeletal calcirudites or with gypsum such as that formed during the messinian salinity crisis the calcirudites lack reef corals calcified green algae and extensive marine cement but exhibit skeletal components described from both modern and fossil nontropical carbonates these include bryozoans mollusks foraminifers echinoderms and minor balanids as well as coralline algae of a bryomol association the presence of some larger foraminifers indicates high temperatures close to the lower temperature threshold of the reef assemblage sea level lowstands and highstands are documented by wedges of bryomol carbonate and chlorozoan patch reefs or prograding platforms thus temperate climate depositional modes correspond to relatively low sea levels and warm water modes to high sea levels the neogene infill of the agua amarga and sorbas basins documents two of these cycles other climate sea level cycles including messinian gypsum in the cool water depositional mode are well established in adjacent neogene basins in southern spain this type of composite sequence seems to occur only along the margin of the global reef belt and indicates an oscillatory latitudinal movement of the margin which is associated with global climatic change the analysis of turnover in neritic depositional carbonate systems may therefore be considered a sensitive tool for reconstructing climatic change from the fossil record however warm water modes and temperate water modes of carbonate sedimentation and diagenesis differ significantly for this reason the interpretation of composite system sequences by sequence stratigraphy requires an extended concept the particular type of mixed bryomolchlorozoan depositional sequence also bears some potential for drowning because sea level rise may be faster than the net production rate of temperate carbonate systems

from platform to basin the evolution of a paleocene carbonate margin eastern desert egypt in this study progradation and the subsequent retrogradation of a late paleocene isolated carbonate platform galala mountains eastern desert egypt is demonstrated by variations of distinct facies associations from the platform margin in the north to the hemipelagic basin in the south a combination of a sea level drop and tectonic uplift at around 59 ma calcareous nannofossil biozone np5 favored the initiation of the carbonate platform from this time onwards the facies distribution along the platform basin transect can be subdivided into five facies belts comprising nine different facies associations their internal relationships and specific depositional settings are strongly coupled with the maastrichtian paleocene seafloor topography which resulted from local tectonic movements patch reefs and reef debris were deposited at the platform margin and the horizontally bedded limestones on the upper slope slumps and debris flows were stored on the lower slope in the subhorizontal toe of slope facies belt mass flow deposits pass into calciturbidites further southwards in the basin only hemipelagic marls were deposited between 59 and 56 2 ma np5 np8 the overall carbonate platform system prograded in several pulses distinct changes in facies associations from 56 2 to 55 5 ma np9 resulted from rotational block movements they led to increased subsidence at the platform margin and a coeval uplift in the toe of slope areas this resulted in the retrogradation of the carbonate platform furthermore the patch reef and reef debris facies associations were substituted by the larger foraminifera shoal association the retrogradation is also documented by a significant decrease in slump and debris flow deposits on the slope and calciturbidites at the toe of slope

sea level changes across the paleocene eocene interval in the spanish pyrenees and their possible relationship with north atlantic magmatism the issue of whether major and rapid global sea level changes existed on a preglacial earth can be resolved by the detailed study of the paleocene eocene p e interval where a large and rapid carbon isotope excursion linked to an important global warming event the paleocene eocene thermal maximum allows for high resolution correlation between terrestrial coastal and marine settings based primarily on outcrop and borehole information from the tremp graus basin in the southern spanish pyrenees it is shown that a sea level fall of at least 20 m occurred less than 75 kyr prior to the petm this forced a seaward displacement of the shoreline of ca 20 km a widespread incision of valleys in the alluvial plains and the subaerial exposure and excavation of the adjacent marine carbonate platform the subsequent sea level rise caused the infilling of the incised valleys a process completed before the onset of the petm and continued rising during and after the event leading to the aggradation of the alluvial plain and eventually to the transgression of the whole tremp graus basin however the sea level did not regain its pre fall position until near the end of the petm therefore although rising the sea level was comparatively low in the southern pyrenean area during most of the petm the pre petm sea level fall has been reported in other basins of the southern pyrenees in the north sea area the austrian alps and in egypt and the subsequent sea level rise has been documented in widely separated sites around the earth an evidence of their global eustatic scope the causal mechanism s of the pre petm sea level fall is are unresolved although glacioeustasy may have played a role the subsequent sea level rise was most likely caused by tectonomagmatic activity in the north atlantic c 2013 elsevier b v all rights reserved less

crustose algal frameworks from the eocene alpine foreland abstract upper eocene algal limestones of the eastern alpine foreland in austria contain three different types of crustose algal frameworks these reveal several similarities with the present day coralligene de plateau of the mediterranean sea but the framework types differ in the crust forming algal taxa the sedimentary regime and the environmental setting 1 the coralline coral frameworks develop from siliciclastic sediments and show a succession from coverstones to bindstone to cruststone initiation of this framework in a siliciclastic regime is only possible because of the occurrence of neogoniolithon sp a species that is able to grow on fine grained soft substrate the onset of a dense crustose framework was related to the reduced sediment input and the occurrence of lithothamnion sp which is able to form cruststones 2 pure coralline algal frameworks are restricted to cruststones dominated by both lithothamnion sp and neogoniolithon sp they formed on top of maerl megaripples during calm periods and shed crustose fragments towards depressions which allowed framework progradation 3 peyssonneliacean dominated frameworks occur with intercalations of coralline algal crusts they formed in muddy environments interpreted as protected depressions between maerl dunes we found that crustose frameworks are controlled by three factors 1 sediment input low input favors the growth of frameworks while coarser grained siliciclastics cause burial of initial algal crusts terrigenous mud influences water turbidity and thus favors the occurrence of peyssonneliacean algae 2 taxonomic composition framework formation requires the existence of crustose algal taxa which are able to grow directly on fine grained soft substrate neogoniolithon sp polystrata alba or to encrust and stabilize coarse grained particles lithothamnion sp and or to form multiple successions of dense crusts lithothamnion sp p alba phymatolithon sp characteristically encrusts corals but it does not contribute to the frameworks surprisingly algae do never form protuberances within the frameworks even if they show protuberant growth forms in maerl sediment 3 substrate stability as a function of substrate composition and hydrodynamic energy due to their occurrence on maerl bottoms and the lack of evidence for submarine hardgrounds the settlement of crustose buildups requires low tidal current activity and or wave agitation

miocene phosphate rich sediments in salento southern italy abstract the upper middle to lower upper miocene serravallian to tortonian sedimentary succession in salento southern italy includes glauconite and phosphate rich deposits which are associated with pelagic micrite in baia del ciolo and marittima southern salento the succession is composed of shallow water platform carbonates of late oligocene age chattian porto badisco formation which are overlain by a 20 to 30 cm thick level of glauconite rich micrite with abundant reworked particles and fossils of the underlying porto badisco formation this interval is in turn covered by an up to 15 cm thick phosphatic crust livello ad aturia which itself is overlain either by a hemipelagic chalk like carbonate of middle to late miocene age pietra leccese marittima or directly by a micrite of late miocene age messinian novaglie formation baia del ciolo which shallows upwards into a shallow water platform carbonate a large hiatus is present in this succession which likely includes the lower and lower middle miocene in the region of lecce two discrete levels enriched in glauconite and phosphate each associated with a major discontinuity occur within the pietra leccese the strontium isotope ages derived on phosphate nodules and phosphatized and non phosphatized fossils and calcareous nannofossil ages indicate a time interval of phosphogenesis between 13 5 and 7 5 ma with two clusters at 12 and 10 5 ma the glauconite and phosphate rich sediments resulted from a current dominated regime which was characterized by low overall sedimentation rates erosion and sediment reworking and authigenesis this regime was likely related to a generally westward directed bottom current which was forced to upwell once it arrived at the western border of the eastern mediterranean basin the timing of the principal phosphogenic phases can only partly be correlated to those of other occurrences in this part of the mediterranean malta gozo southern sicily matese latium abruzzi platform the partial diachrony in phosphogenesis may express the effect of lateral switching in and or focusing of upwelling zones

studies on settling traction and entrainment of larger benthic foraminiferal tests implications for accumulation in shallow marine sediments settling and traction velocities were measured on optimally preserved tests of larger foraminifera using a settling tube and flume tank within larger foraminifera with porcelaneous tests the peneroplids peneroplis antillarum p planatus p pertusus and dendritina cf d zhengae are distinguished by low test densities ca 1 2 that do not change with growth buoyancy is high because of low reynolds numbers and increases in large individuals because of the allometric change of test shape the fusiform alveolinella quoyi with test densities ca 1 6 is characterized by high reynolds numbers inducing the weakest buoyancy within porcelaneous larger foraminifera the highest buoyancy was recorded for the three soritids parasorites orbitolitoides sorites orbiculus and amphisorus hemprichii because of their low test densities ca 1 25 and the extremely flat biconcave plate like shape flat tests however reduce traction and entrainment from smooth surfaces within hyaline larger foraminiferat the amphisteginids show thick lenticular amphistegina lobifera a radiata to thin lenticular tests a bicirculata a papillosa influencing buoyancy here high test densities ca 1 8 decrease with growth in a lobifera a lessonii and a bicirculata and remain constant in a radiata and a papillosa minimum velocities required for entrainment are lower for thick lenticular tests and higher for thin lenticular tests test densities remain constant with growth in the calcarinid baculogypsina sphaerulata 1 78 and decrease slightly in calcarina gaudichaudii and neorotalia calcar starting at 1 85 all living under extreme hydrodynamic conditions density decreases the most in baculogypsinoides spinosus starting at 1 8 resulting in higher buoyancy through low reynolds numbers traction is promoted in spherical tests of baculogypsina and baculogypsinoides within nummulitids the thick lenticular palaeonummulites venosus test density decreasing with size starting at 1 78 is less buoyant expressed in high reynolds numbers but easily entrained thick lenticular juveniles and extremely flat adults distinguish operculinella cumingii heterostegina depressa and the giant cycloclypeus carpenteri test densities increase during growth starting from ca 1 6 and attaining a maximum of 1 8 buoyancy is low in small tests and high in large tests while entrainment velocities are reduced as the tests flatten high buoyancy is also a characteristic of the entirely flat tests in operculina ammonoides from deeper regions and planostegina operculinoides which is expressed in the lowest reynolds numbers within larger foraminifera

paleocene to eocene benthic foraminiferal isotopes and assemblages implications for deepwater circulation early paleogene warm climates may have been linked to different modes and sources of deepwater formation warm polar temperatures of the paleocene and eocene may have resulted from either increased atmospheric trace gases or increased heat transport through deep and intermediate waters the possibility of increasing ocean heat transport through the production of warm saline deep waters wsdw in the tethyan region has generated considerable interest in addition general circulation model results indicate that deepwater source regions may be highly sensitive to changing basin configurations to decipher deepwater changes we examined detailed benthic foraminiferal faunal and isotopic records of the late paleocene through the early eocene 60 to 50 ma from two critical regions the north atlantic bay of biscay site 401 and the pacific shatsky rise site 577 these records are compared with published data from the southern ocean maud rise site 690 islas orcadas rise site 702 during the late paleocene similar benthic foraminiferal 18o values were recorded at all four sites this indicates uniform deepwater temperatures consistent with a single source of deep water the highest 13c values were recorded in the southern ocean and were 0 5 more positive than those of the pacific we infer that the southern ocean was proximal to a source of nutrient depleted deep water during the late paleocene upper paleocene reflector ab was cut on the western bermuda rise by cyclonically circulating bottom water also suggesting a vigorous source of bottom water in the southern ocean a dramatic negative excursion in both carbon and oxygen isotopes occurred in the latest paleocene in the southern ocean this is a short term 100 kyr globally synchronous event which also is apparent in both the atlantic and pacific records as a carbon isotopic excursion of approximately 1 faunal analyses from the north atlantic and pacific sites indicate that the largest benthic foraminiferal faunal turnover of the cenozoic was synchronous with the isotopic excursion lending support to the hypothesis that the extinctions were caused by a change in deepwater circulation we speculate that the southern ocean deepwater source was reduced or eliminated at the time of the excursion during the early eocene southern ocean 13c values remained enriched relative to the north atlantic and pacific however the southern ocean was also enriched in 18o relative to these basins we interpret that these patterns indicate that although the southern ocean was proximal to a source of cool nutrient depleted water the intermediate to upper deep water sites of the north atlantic and pacific were ventilated by a different source that probably originated in low latitudes i e wsdw

sub wavebase cross bedded grainstones on a distally steepened carbonate ramp upper miocene menorca spain cross bedded grainstones on carbonate ramps and shelves are commonly related to the locus of major wave energy absorption such as shorelines shoals or shelf breaks in contrast on the early tortonian carbonate platform of menorca balearic islands coarse grained cross bedded grainstones are found at a distance from the palaeoshoreline where they were deposited below the wavebase excellent exposures along continuous outcrops on the sea cliffs of menorca reveal the depositional profile and three dimensional distribution of the different facies belts of the tortonian ramp depositional system basinward from the palaeoshoreline fan deltas and beach deposits pass into 5 km wide gently dipping bioturbated dolopackstone inner and middle ramp then into 12 20 dipping dolograinstone rudstone clinobeds ramp slope and finally into subhorizontal fine grained basinal dolowackestone to dolopackstone outer ramp in this miocene example coarse grained grainstones exist in five different settings other than beach deposits 1 on the middle ramp where cross bedded grainstones were deposited by currents roughly parallel to the shoreline at 40 70 m estimated water depth and are interbedded with gently dipping bioturbated dolomitized packstones 2 on the upper slope where clinobeds are composed mostly of in situ rhodoliths and red algae fragments 3 on the lower slope as small scale bedforms small three dimensional subaqueous dunes migrating parallel to the slope 4 at the transition between the lower slope and the outer ramp where mollusc rich and rhodolithic rudstones and grainstones interbedded in dolomitized laminated wackestones containing abundant planktonic foraminifera infill slide slump scars as upslope backstepping bodies backsets 5 at the toe of the slope where coarse skeletal grainstones indicate bedform migration parallel to the platform margin induced by currents at more than 150 m estimated water depth this late miocene example also illustrates how changes in intrabasinal environmental conditions nutrients and or temperature may produce changes in stratal patterns and facies architecture if they affect the biological system two depositional sequences compose the miocene platform on menorca where a reef rimmed platform prograded onto an earlier distally steepened ramp the transition from the ramp to the reef rimmed platform was effected by an increase in accommodation space caused by ecological changes promoting a shift from a grain to a framework producing biota

carbonate ramp depositional systems abstract the classification tectonic settings stratigraphy and early diagenesis of carbonate ramp systems are reviewed carbonate ramps are common in all geological periods but were dominant at times when reef constructing organisms were absent or inhibited ramps can be subdivided into inner mid and outer ramp environments the mid ramp zone extends from fair weather wave base to normal storm wave base although the water depths which these boundaries represent vary an additional outer slope environment occurs on distally steepened ramps as with siliciclastic shelves a range of wave storm and tide dominated ramps can be recognised and this forms the most convenient basis for ramp classification the carbonate productivity profile of ramps differs from that of rimmed shelves with the inner ramp showing lower production rates than comparable shallow water facies on rimmed shelves the zone of greatest organic carbonate sediment production appears to have shifted from the mid ramp to the inner ramp since the late jurassic carbonate ramps occur in most types of sedimentary basin but are best developed where subsidence is flexural and gradients are slight over large areas as in foreland and cratonic interior basins and along passive margins the featureless depositional profiles of many ramps means that sequence geometries are best observed on regional seismic lines some show low angle sigmoidal or shingled clinoforms suggesting that ramps may seldom be homoclinal but possess subtle slope geometries which reflect depositional environments because of their low angle slopes ramps respond differently to rimmed shelves during relative sea level changes although results seem to be strongly dependent on the rate of relative sea level change during a minor fall shallow ramp facies belts will simply shift basinwards in a forced regression in contrast the whole surface of a steep sloped flat topped rimmed shelf may be exposed so that sediment production ceases or is drastically reduced during a major fall shallow ramp bounded basins may empty completely conversely ramps also flood gradually whereas rimmed shelves do so more rapidly homoclinal ramps develop no resedimented lowstand deposits rimmed shelves and distally steepened ramps in contrast may develop lowstand talus or turbiditic wedges distally steepened ramps may behave more like homoclinal ramps during minor base level falls and like rimmed shelves during major base level falls many ramps consist of layered successions of several ramp sequences stacked one upon the other ramp stacks of this sort may show gross vertical accretion but individual ramp sequences seldom appear to develop in a keep up style apart from minor organic buildups as with many rimmed shelves steepening of the outer ramp margin due to tectonism slope inheritance or differential sedimentation may promote the development of a distally steepened ramp or rimmed shelf a wide variety of organisms have constructed buildups in mid and outer ramp environments isolated buildups may seed early in ramp development accrete to wave base or sea level and continue growth by stacking through successive ramp sequences so that depositional and diagenetic features within them are in concert with those of the shallow ramp the location of isolated buildups on ramps is governed by tectonism halokinesis antecedent topography or by the subtle slope geometry of the previous ramp sequence diagenesis on ramps shows some major variations compared with diagenesis on steep sloped flat topped carbonate platforms ramp bounded basins may form prolific petroleum sourcing and reservoiring systems and offer a range of subtle stratigraphic play types and lateral facies variations which determine reservoir quality and distribution isolated buildups in the mid and outer ramp environments represent one of the commonest petroleum reservoirs in ramp systems and tend to have their foundations in transgressive systems tracts grainstone and packstone reservoirs are widespread and range from shoreline carbonate sandbodies to major detached shoal complexes or shoals over offshore highs grainstone sandbodies occur in both highstand systems tracts and in prograding lowstand wedges

estimating mediterranean oligocene miocene sea surface temperatures an approach based on coral taxonomic richness abstract during the oligocene and miocene shallow water carbonates of the mediterranean region were rich in scleractinian corals thriving within various depositional settings including different reef types their diversity patterns although related to a complex interplay between a suite of environmental factors and palaeobiogeography are considered to be strongly controlled by climate variability and changes in sea surface water temperature by using the quantitative relationship between present day coral taxonomic richness and prevailing sea water temperature underlined by the so called energy hypothesis we test zooxanthellate coral generic richness values from a selection of 102 oligocene miocene localities of the mediterranean region as a proxy for relative palaeotemperatures for each oligocene miocene stage generic richness values per z coral site are firstly examined together with variations of the mediterranean z coral generic pool for better testing the method and assessing its potential application patterns of generic richness and inferred palaeotemperatures are then compared with global palaeoclimatic curves based on marine oxygen stable isotopes data or other climate proxies such as palaeoclimatic records from european continental floras and from fossil coral linear extension rate results clearly show that fluctuations of coral richness derived palaeotemperatures correspond relatively well with global changes of sea water temperature especially for the entire oligocene the chattian aquitanian boundary and the late miocene the well known mid miocene climatic optimum however is not recorded suggesting that regional factors acting together with important palaeogeographical changes exerted a strong control on the generic richness of mediterranean z coral communities a remarkable decline of taxonomic richness is recorded after the burdigalian together with a gradual decrease of palaeotemperatures in the region from the middle miocene onwards to the messinian however an increase in the temperature range of z coral localities is clearly visible indicating that z coral communities were able to thrive and adapt to a wider temperature range as the mediterranean was gradually migrating northwards outside the tropical belt the energy hypothesis if used at global or regional scale can be considered a promising and reliable method for estimating cenozoic palaeotemperatures from coral or other suitable fossil assemblages of shallow water carbonates

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

carbonate ramp evolution during the late oligocene chattian salento peninsula southern italy abstract oligocene carbonate ramps and platforms are widespread and though they are important carbonate reservoirs detailed studies on the facies organization platform type and internal architecture are scarce within this context the chattian carbonate units cropping out in salento southern italy allow detailed study of the distribution of skeletal components and facies architecture the lower chattian castro limestone previously considered as a fringing reef is reinterpreted as a distally steepened ramp with a distal talus induced by a paleo escarpment in the substrate epiphytic biota and sediment dweller organisms thriving in seagrass meadows dominated production in the shallow water euphotic zone seawards large rotalid foraminifers dominated a detritic mesophotic zone near the edge of the escarpment also in the mesophotic zone luxurious growth of corals built discrete mounds with no evidences of wave resistant growth fabrics basinward 25 to 30 dipping clinobeds abut against the escarpment where coral rudstone floatstone textures resulted from downfall of corals and sediments the upper chattian porto badisco calcarenite represents a homoclinal ramp dominated by packstone textures in the euphotic inner ramp autochthonous biota suggests the occurrence of extensive seagrass meadows basinward large rotalid packstone and small coral mounds developed in mesophotic conditions and rhodolithic floatstone to rudstone and large lepidocyclinid packstone characterize the sediments of the deeper oligophotic zone comminuted skeletal debris depleted of light dependent organisms typifies deposition in the dysphotic aphotic zone in both examples the middle ramp meso oligophotic zones was the most prolific in terms of carbonate production whereas shallow water seagrass related production euphotic was much less important corals built mounds also in the mesophotic zone but never reached sea level hydrodynamic conditions in the meso oligophotic zone are better explained by breaking of internal waves and their induced up and down slope currents instead of the surface storm waves

components facies and ramps redefining upper oligocene shallow water carbonates using coralline red algae and larger foraminifera venetian area northeast italy abstract chattian mixed carbonate siliciclastic deposits from two palaeogeographic units of southern alps the lessini shelf and venetian foreland basin of northeast italy are studied with respect to facies distributions and controlling ecological factors on dominant biogenic components these ramp depositional systems are located in the western southern alps on the lessini shelf and in the eastern southern alps in the venetian foreland basin the successions show an extensive geographic distribution of at least 150 km 40 km at the southern margin of the southern alps palaeoenvironments are inferred following microfacies characteristics and floral and faunal indicators especially those of coralline red algae and larger foraminifera an inner to middle homoclinal ramp morphology is reconstructed based on facies distributions and taxonomic and coralline algal growth form proxy data the distribution along depositional strike shows variation from thinner carbonate dominated sequence in the west monti berici and monti lessini to a more variable mixed carbonate siliciclastic dominated environment to the east vittorio veneto alpago facies character and occurrence are controlled by local hydrodynamic conditions and varying water turbidity of the studied ramp depositional system the general facies succession shows a transgressive sequence from the proximal inner to proximal middle ramp a shoal belt of trough cross bedded sandstones occurs in a proximal inner ramp position in all of the studied areas in a gentle dipping homoclinal ramp most benthic organisms inhabited the relatively quite environments off these shoals in a distal inner ramp setting basinward environments proximal middle ramp constitute areas of maximal carbonate production and consist primarily of larger foraminiferal facies and rhodolith pavements larger foraminifera represented by two larger foraminiferal assemblages are most diversified in the shallower settings near the fair weather wave base distal inner proximal middle ramp whereas coralline algae predominate in deeper areas proximal middle ramp constructing extensive rhodolith pavements rhodolith pavements are distinguished with respect to rhodolith shape size growth forms and coralline algal taxonomic composition larger foraminifera are interpreted with respect to shell structures shell architectures and comparable recent counterparts the analysed benthic communities thrived in a mesotrophic regime within trophic gradients constrained by fluvial influence coralline algal dominance and a moderately diverse larger foraminiferal assemblage suggest a tropical warm temperate transition the considerable stability imposed on sediments by the rhodolith pavement must also have significantly contributed to the maintenance of a middle ramp profile bulge this study will contribute to a better understanding of oligocene carbonates which have received less attention than their eocene or miocene counterparts

the formation and fate of internal waves in the south china sea internal oceanic waves are subsurface gravity waves that can be enormous and travel thousands of kilometres before breaking but they are difficult to study here observations of such waves in the south china sea reveal their formation mechanism extreme turbulence relationship to the kuroshio current and energy budget internal waves are the underwater version of more familiar surface waves they can be enormous and travel thousands of kilometres before breaking the south china sea is known to be home to the largest internal waves in the world s oceans but their size generation mechanisms and role in the regional energy budget are unknown matthew alford and colleagues now present the results from the iwise observational campaign and reveal that internal waves more than 200 metres high break in the south china sea and create turbulence that is orders of magnitude larger than in the open ocean and that wave formation is influenced by the kuroshio current these results now allow for a complete energy budget of the south china sea and for a more accurate incorporation of internal waves into climate models internal gravity waves the subsurface analogue of the familiar surface gravity waves that break on beaches are ubiquitous in the ocean because of their strong vertical and horizontal currents and the turbulent mixing caused by their breaking they affect a panoply of ocean processes such as the supply of nutrients for photosynthesis1 sediment and pollutant transport2 and acoustic transmission3 they also pose hazards for man made structures in the ocean4 generated primarily by the wind and the tides internal waves can travel thousands of kilometres from their sources before breaking5 making it challenging to observe them and to include them in numerical climate models which are sensitive to their effects6 7 for over a decade studies8 9 10 11 have targeted the south china sea where the oceans most powerful known internal waves are generated in the luzon strait and steepen dramatically as they propagate west confusion has persisted regarding their mechanism of generation variability and energy budget however owing to the lack of in situ data from the luzon strait where extreme flow conditions make measurements difficult here we use new observations and numerical models to 1 show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena 2 reveal the existence of 200 metre high breaking internal waves in the region of generation that give rise to turbulence levels 10 000 times that in the open ocean 3 determine that the kuroshio western boundary current noticeably refracts the internal wave field emanating from the luzon strait and 4 demonstrate a factor of two agreement between modelled and observed energy fluxes which allows us to produce an observationally supported energy budget of the region together these findings give a cradle to grave picture of internal waves on a basin scale which will support further improvements of their representation in numerical climate predictions

carbonate mound development at the sw rockall trough margin based on high resolution tobi and seismic recording abstract in 2002 high resolution sidescan sonar images of a mound area at the sw rockall trough margin were recorded with the tobi deep towed sidescan sonar processed tobi images with a pixel resolution of 6 m provide a unique overview of the carbonate mound distribution and related sedimentary features around the mounds three morphologically distinct areas can be recognised on the tobi mosaic in area i between 500 and 600 m water depth upslope of the mounds giant sediment waves are found with wavelengths up to 500 m with wave crests of more than 10 km long and with an amplitude of up to 30 m reflected with a high backscatter on the tobi image area ii between 600 and 1000 m water depth along the upper margin flank is characterised by clustered and isolated carbonate mounds forming elongated ridges with an orientation perpendicular to the slope sedimentary structures such as flow ridges sediment waves local scouring at the foot of some mounds and draping of sediment around mounds indicate the influence of strong near bed currents oriented in two main current directions parallel to the margin as well as in a similar direction as the mound clusters the mound clusters are several kilometres long can be over 380 m high and are dissected by downslope directed channels on the tobi image the mounds appear as regions of high backscatter caused by the presence of cold water coral colonies on the sediment and by distinct shadows all mounds have their tops at a specific depth level 500 600 m water depth area iii between 900 and 1200 m water depth below the mounds is characterised by disturbed sediments with distinct slump scars and flow ridges 2d high resolution seismic profiling perpendicular and parallel to the slope across the mounds does in general not reveal strong internal reflectors within the mounds in contrast three strong reflectors can be observed in the sedimentary sequence underneath the mounds the upper reflector c10 of early pliocene age is an erosional unconformity above which most of the mounds and sediment waves seem to have developed the second erosional unconformity c20 of middle miocene age is formed by an apparent irregular surface that locally is dissected by some small faults reflectors c10 and c20 have been found in two different mound clusters in the mound area indicating that mound development possibly started after formation of reflector c20 the third reflector forms the acoustic basement which is locally dissected by some small faults that are located below the mounds at least two stages of mound formation are recognised on the seismic profiles

reconstruction of the late miocene climate of spain using rodent palaeocommunity successions an application of end member modelling abstract end member modelling is applied to a data set of relative abundances of 67 upper miocene rodent associations 11 6 ma from spain france austria and greece the analysis results in the robust estimation of relative levels of four climatic parameters humidity temperature seasonality type and predictability in the preparatory stage species are aggregated into nine groups on the basis of ecological criteria humidity preferences and adaptations are based on actualistic and functional morphological interpretations of dentition and locomotion temperature preferences are inferred from palaeobiogeographic distributions levels of adaptation to seasonality type wet dry or cool warm seasonality are assigned on the basis of diversities in present day climate vegetation zones and the ability of extant relatives to hibernate demographic data are used to formulate adaptations to climatic un predictability in the modelling stage the compositions are unmixed into the contributions of four end members these four extreme theoretical rodent compositions are interpreted in climatic terms and their contributions to the samples are used for the estimation of climatic parameters the subset of 44 well dated rodent compositions from the calatayud daroca and teruel basins ne spain is used to construct detailed climatic curves for the late miocene while the geographical dimension in the data set is used to calculate inter basinal differences the model results for spain indicate more humid and cooler conditions between 10 5 and 8 5 ma around 7 and around 6 ma and more arid and warmer conditions before 10 5 between 8 6 and 7 5 ma and around 6 5 ma superimposed on this pattern is a shift from a more predictable cool warm seasonal climate towards a more unpredictable wet dry seasonal climate between 9 4 and 8 2 ma inter basinal comparisons per time slice show that the climate in southern europe was dryer warmer more wet dry seasonal and more unpredictable than in central europe and that the climatic and vegetational boundaries between the two regions were sharp the occurrences of more humid and cooler episodes in spain during the late miocene might be explained by southward migrations of the boundary between a temperate and subtropical dry climatic belt and their associated vegetation types various positive correlations are observed between the rodent based climatic curves for spain and other palaeoclimatic records from the mediterranean and ne atlantic region clay minerals marine fauna stable isotopes the two cooling maxima at 9 4 and 7 ma closely correspond to clusters of marine events which are generally considered to reflect maxima of global ice volume

geographic and temporal patterns in the late neogene 12 3 ma aridification of europe the use of small mammals as paleoprecipitation proxies abstract present day relations between small mammal community structure and rainfall are used to predict late neogene 12 3 ma precipitation patterns in europe and anatolia new proxy methods are developed which include regressions of mean annual and minimum monthly precipitation on diet invertivory index and locomotion habitat arboreality index a series of precipitation maps and a set of regional precipitation curves through time at 1 myr resolution are presented precipitation curves at a higher temporal resolution are constructed for the region of central spain the miocene results show the existence between 12 and 9 ma of a large wet 800 1200 mm yr zone extending from northern spain to the ukraine and characterized by the whole year penetration of large amounts of moisture far into the continent between 10 9 and 5 ma this european temperate wet zone etwz shrinks and or moves northward resulting in diachronous aridification a coeval northward migration of the subtropical high pressure zone shpz is hypothesized which is also consistent with the predicted onset of seasonal summer dryness between 10 and 8 ma the maximum extension of the etwz at 12 9 ma temporally correlates with northern hemisphere cooling suggesting that climate zonation rather than the global amount of atmospheric moisture controlled european climate at this time the main aridification at 9 8 ma could best be explained by a northward extension shifting of the subtropical high pressure zone and a transition towards less zonal circulation processes which ultimately could have been triggered by uplift of the tibetan plateau a temporary increase of precipitation at 7 6 ma is associated with renewed global cooling the lowest precipitation values less than 400 mm yr occur during the pliocene in southern and eastern europe uplift in eastern europe carpathians shrinking of the paratethys could well explain the aridification in this area and the associated sharpening of east west precipitation gradients across the continent

ecological control of sedimentary accommodation evolution from a carbonate ramp to rimmed shelf upper miocene balearic islands abstract stratal patterns and facies architecture develop in response to sediment flux and the available space for sediment accumulation accommodation in siliciclastic systems these two parameters are independent in carbonates however they are highly interdependent 1 sediment input production highly depends on biological systems and consequently on intrabasinal conditions nutrients temperature salinity etc 2 sediment dispersal depends on the production loci and on the interaction between the amount and type of sediment being produced and the hydraulic energy additionally biological processes binding baffling framework construction and even cementation frequently modify it 3 accommodation is not an independent factor with respect to sediment input type efficiency and area of the carbonate factory depend on sea level changes and sea floor morphology the base level for sediment to accumulate accommodation depends on the type and locus of sediment being produced the upper miocene carbonate platforms of the balearic islands illustrate how changes in intrabasinal environmental conditions nutrients and or temperature produce changes in stratal patterns and facies architecture if they affect the biological system during early tortonian carbonate production occurred both in the shallow euphotic zone foramol and in the deeper oligophotic zone rhodalgal originating a distally steepened ramp during late tortonian and early messinian carbonate production mainly occurred in the euphotic zone where framework producing biota coral reefs formed a rimmed platform although deposited under similar conditions of high frequency sea level fluctuations these two types of platforms exhibit different internal facies architecture and distribution of heterogeneities because of differences in base level in carbonates base level for sediment accumulation depends on the type and amount of sediment being produced on the production loci and on the processes controlling sediment dispersal base level for the loose foramol rhodalgal sediment associations of the ramp was controlled by wave and storm base and the associated currents whereas base level for the framework dominated reef complex was sea level furthermore the increase on effective accommodation space to allow the reef rimmed shelf to prograde onto the distally steepened ramp both platforms being depositional sequences resulted from an ecological change rather than significant relative sea level change namely by the shift from grain to framework producing biota the euphotic framework producing biota was able to fill the accommodation space existing between wave and storm base level and sea level that was not previously filled by the loose bioclasts

insights from the paleogene tropical pacific foraminiferal stable isotope and elemental results from site 1209 shatsky rise 1 stable isotope and elemental measurements were conducted on foraminifera from a sequence of calcareous pelagic ooze at ocean drilling program site 1209 to document the thermal evolution of the north pacific water column over shatsky rise and to address long standing questions about the nature of oceanic circulation in the early paleogene a major change in seasonality and water column structure in the early eocene marks a change in tropical pacific climate and circulation just prior to the early eocene climatic optimum subsequent long term cooling is interrupted by a transient positive 18o excursion identified in planktonic and benthic foraminifera during the late early eocene that is interpreted as evidence for ephemeral formation of deep water from a low latitude saline source paired analysis of benthic mg ca and 18o was undertaken to assess the relative contribution of temperature and seawater oxygen isotope composition to the benthic 18o record stratigraphic trends of benthic 18o and mg ca decouple during two intervals in the early eocene and early middle eocene although variable seawater 18o is the most likely candidate to explain decoupling of benthic 18o and mg ca it is difficult to argue for substantial change in continental ice volume during a presumably ice free interval of time

neritic isotope and sedimentary records of the eocene oligocene greenhouse icehouse transition the calcare di nago formation northern italy in a global context abstract from the middle eocene to early oligocene the earth experienced the most significant climatic cooling of the cenozoic era the eocene oligocene transition eot represents the culmination of this climatic cooling leading to the onset of the antarctic glaciation and consequently to the beginning of the present day icehouse world whereas the response of deep sea systems to this climate transition has been widely studied its impact on the shallow water carbonate realm is poorly constrained here the sedimentary expression of the eot in two shallow marine carbonate successions nago and san valentino northern italy belonging to the calcare di nago formation is presented the chronostratigraphic framework was constructed by integrating litho bio and isotope stratigraphic data c and sr isotopes allowing to correlate these shallow marine successions with pelagic sections in central italy massignano tanzania tdp sites 12 and 17 and the indian ocean odp site 744 within several sections in northern italy including nago and san valentino a priabonian late eocene transgression is recorded oxygen isotopes of odp site 744 show a coeval negative shift of 0 4 suggesting a glacio eustatic origin for this transgression in the nago and san valentino sections no prominent sequence boundary has been detected that would indicate a rapid sea level drop occurring together with the positive shift in 18o defining the eot 1 cooling event instead a gradual shallowing of the depositional environment is observed at tdp sites 12 and 17 the eot 1 is followed by a negative shift in 18o of around 0 4 which correlates with a relative deepening of the environment in the studied sections and suggests a melting pulse between eot 1 and the oligocene isotope event 1 oi 1 the positive 18o shift related to the oi 1 translates in san valentino into a change in carbonate factory from a photozoan association dominated by larger benthic foraminifera corals and red algae to a heterozoan association dominated by bryozoans the same bryozoan facies occurs in several italian localities near the eocene oligocene boundary this facies is interpreted to represent an analogue of modern cool water carbonates and results from a cooling pulse of at least regional scale associated to the oi 1 event

nutrients sea level and tectonics constrains for the facies architecture of a miocene carbonate ramp in central italy in the western part of the central apennines lower middle miocene carbonates were deposited on a tropical subtropical carbonate ramp they record two long term cycles the first of which is illustrated in this paper between 21 and 17 5 ma miocene carbonates paraconformably overlying the cretaceous limestones record a transgressive event during a time of global 2nd order sea level lowstand it is postulated that this deviation is related to an increase in tectonic subsidence between 17 5 ma and 16 15 ma with a progressive relative sea level rise the inner middle ramp facies belt stepped back whereas the bryozoan dominated outer ramp facies belt stepped back but simultaneously prograded this bloom of suspension feeding organisms is interpreted to reflect an increased nutrient availability hence a change from oligotrophic to eutrophic conditions strontium isotope dates constrain correlation of the second phase with a eutrophic event possibly linked to the influence of the neighbouring apenninic accretionary wedge and foredeep system

environmental factors influencing skeletal grain sediment associations a critical review of miocene examples from the western mediterranean the presence of foramol rhodalgal and bryomol skeletal grain associations in ancient shallow marine limestones is commonly interpreted as evidence for non tropical palaeoclimate despite temperature being only one of several factors influencing skeletal grain associations such interpretations neglect the multitude of factors other than temperature that influence carbonate producing biota these include nutrients water energy water transparency depth of the sea floor salinity oxygen ca2 and co2 concentrations mg ca ratio alkalinity substrate requirements competitive displacement as well as biological and evolutionary trends this uniformitarian approach also disregards the probability that conditions of present day biological systems may not be representative of past conditions of analogous systems here the importance of considering these other factors is illustrated through two examples of carbonate platforms in the western mediterranean these platforms are dominated by foramol rhodalgal and bryomol associations of miocene age in spite of having formed in tropical conditions the platforms discussed are 1 the lower tortonian ramp on menorca balearic islands and 2 the lower middle miocene ramps of the central apennines italy evidence for tropical conditions in the mediterranean during the period of growth of these platforms is provided by species of red algae and larger foraminifera by data from coeval continental basins and by global oxygen isotope data

reef building and carbonate production modes in the west central tethys during the cenozoic abstract changing components rock textures lithofacies platform types and architecture throughout time are unique characteristics of carbonate rocks characterizing these attributes has been approached by 1 building reference models for specific phanerozoic intervals 2 recognizing the climatic impact in modulating carbonate production and 3 analyzing the influence of changing bio geochemical conditions the reference model approach is mostly based on biological evolution the climatic impact approach emphasizes temperature and the bio geochemical approach considers the changes in mg ca ratios and ca concentrations in the oceans to date however an analysis integrating all of these factors is still missing the analysis presented here includes all these factors but also co 2 which is fundamental for both photosynthesis and caco 3 precipitation here we analyze the waxing and waning of cenozoic reef limestones from the central tethys region through several steps 1 on the basis of rock volume rock textures associated sediments and light dependent skeletal components as records of light penetration and wave energy depth 2 on global environmental conditions 13 c 18 o p co 2 temperature and 3 on the basis of functionality nutritional requirements and available resources through the cenozoic water motion whether induced by surface or internal waves or by currents increased as the thermal gradients strengthened both with depth and with latitude active water motion is essential for plankton catchers such as corals but less so for many larger benthic foraminifers lbf pycnoclines in the meso oligophotic zone would then favor the benthic plankton catchers such as corals but would be detrimental for many lbf warm temperatures favored lbf the eocene lbf families predominated during lowering of atmospheric p co 2 by using respiratory co 2 to enhance the symbiont production of photosynthates under oligotrophic conditions and limited turbulence whereas the miocene families had to adapt to a progressive increase in turbulence the eurythermal coralline red algae however became preponderant producers in the mesophotic zone during times when the 13 c was relatively high this explains two apparent paradoxes 1 corals thrive best when the earth s high latitudes cool and 2 the dominance of corals and lbf is inversely correlated despite they both require tropical conditions and have similar trophic strategies mixotrophy

climatically driven changes in sediment supply on the sw iberian shelf since the last glacial maximum the assemblages of marine sediments on the sw iberian shelf have been controlled by contributions from distinct sources which have varied in response to environmental changes since the last glacial maximum lgm the rapid decadal scale mediterranean overturning circulation permits mixing of suspended particles from the entire mediterranean sea they are entrained into the suspended particulate matter spm carried by mediterranean outflow water mow which enters the eastern north atlantic through the strait of gibraltar and spreads at intermediate depths in the gulf of cadiz and along the portuguese continental margin other major sediment sources that have contributed to the characteristics and budget of spm along the flow path of mow on the sw iberian shelf are north african dust and river transported particles from the iberian peninsula to reconstruct climate and circulation driven changes in the supply of sediments over the past 23 000 cal yr b p radiogenic nd sr and pb isotope records of the clay size sediment fraction were obtained from one gravity core in the gulf of cadiz 577 m water depth and from two gravity cores on the portuguese shelf 1745 m 1974 m water depth these records are supplemented by time series analyses of clay mineral abundances from the same set of samples contrary to expectations the transition from the lgm to the holocene was not accompanied by strong changes in sediment provenance or transport whereas heinrich event 1 h1 and the african humid period ahp were marked by significantly different isotopic signatures reflecting changes in source contributions caused by supply of ice rafted material originating from the north american craton during h1 and diminished supply of saharan dust during the ahp the data also reveal that the timing of variations in the clay mineral abundances was decoupled from that of the radiogenic isotope signatures

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

late cretaceous neogene trends in deep ocean temperature and continental ice volume reconciling records of benthic foraminiferal geochemistry δ18o and mg ca with sea level history 1 we reconstruct trends in ice volume and deep ocean temperature for the past 108 myr resolving variations on timescales of 2 myr and longer we use a sea level record as a proxy for ice volume a benthic foraminiferal mg cabf record as a proxy for temperature and a benthic foraminiferal 18obf record as a proxy for both this allows us to construct dual estimates of temperature and ice volume variations for the interval 10 60 ma extracting temperature from 18obf by using sea level as a proxy for ice volume to constrain the 18osw component and extracting seawater 18osw which reflects ice volume from 18obf by using mg cabf to constrain the temperature component each of these approaches requires numerous assumptions but the range of plausible solutions are concordant on timescales 2 myr and within an uncertainty of 2 c temperature and 0 4 18osw the agreement between the two approaches for the last 50 myr provides empirical justification for the use of 18obf mg cabf and sea level records as robust climate proxies our reconstructions indicate differences between deep ocean cooling and continental ice growth in the late cenozoic cooling occurred gradually in the middle late eocene and late miocene pliocene while ice growth occurred rapidly in the earliest oligocene middle miocene and plio pleistocene these differences are consistent with climate models that imply that temperatures set by the long term co2 equilibrium should change only gradually on timescales 2 myr but growth of continental ice sheets may be rapid in response to climate thresholds due to feedbacks that are not yet fully understood

climate modulates internal wave activity in the northern south china sea 2015 the authors internal waves iws generated in the luzon strait propagate into the northern south china sea nscs enhancing biological productivity and affecting coral reefs by modulating nutrient concentrations and temperature here we use a state of the art ocean data assimilation system to reconstruct water column stratification in the luzon strait as a proxy for iw activity in the nscs and diagnose mechanisms for its variability interannual variability of stratification is driven by intrusions of the kuroshio current into the luzon strait and freshwater fluxes associated with the el nino southern oscillation warming in the upper 100m of the ocean caused a trend of increasing iw activity since 1900 consistent with global climate model experiments that show stratification in the luzon strait increases in response to radiative forcing iw activity is expected to increase in the nscs through the 21st century with implications for mitigating climate change impacts on coastal ecosystems

large amplitude leaky island generated internal waves around palau micronesia three years of temperature data along two transects extending to 90 m depth at palau micronesia show twice a day thermocline vertical displacements of commonly 50 100 m and on one occasion 270 m the internal wave occurred at a number of frequencies there were a number of spectral peaks at diurnal and semi diurnal frequencies as well as intermediate and sub inertial frequencies less so at the inertial frequency at palau the waves generally did not travel around the island because there was no coherence between internal waves on either side of the island the internal waves at a site 30 km offshore were out of phase with those on the island slopes suggesting that the waves were generated on the island slope and then radiated away palau island was thus a source of internal wave energy for the surrounding ocean a numerical model suggests that the tidal and low frequency currents flowing around the island form internal waves with maximum wave amplitude on the island slope and that these waves radiate away from the island the model also suggests that the headland at the southern tip of palau prevents the internal waves to rotate around the island the large temperature fluctuations commonly daily fluctuations 10 c peaking at 20 c appear responsible for generating a thermal stress responsible for a biologically depauperate biological community on the island slopes at depths between 60 and 120 m depth

scleractinian assemblages under sediment input their characteristics and relation to the nutrient input concept abstract in the geological record scleractinian dominated turbid water bioconstructions that accumulated under substantial terrigenous input along with shallow neritic marls rich in well preserved corals are common these occurrences indicate that beyond some threshold the ecologic and taphonomic effects of sedimentation prevail over the effects of nutrification field data and experiments on recent corals show that some taxa cope well with terrigenous turbidity and sedimentation and acclimate to increased heterotrophy colonial corals resilient to sediment input commonly are massive to platy forms of high skeletal plasticity and with large polypars to effectively reject sediment or are branched species providing a very small sedimentation area cleaned by feeble currents or small polyped massive taxa that tolerate intermittent veneering by sediment these corals may comprise siltation assemblages of recent turbid water reefs and level bottoms in siliciclastic environments conversely excess input of even low amounts of dissolved inorganic nutrients into clear waters adversely affects many coral species fossil turbid water bioconstructions twb were situated in inner shelf to shore zone settings or near storm wave base on shelves or ramps did not stack into reef complexes mostly show a cluster to segment fabric are scarce in or devoid of frame pores with marine cement and lacked a high carbonate slope relative to fossil clear water buildups preserved in pure limestone successions fossil twb contain moderately diverse coral assemblages with an increased proportion of sediment resistant forms aside from coral behaviour that is elusive in fossils the sediment resistance of corals was mainly determined by colony shape and polypar size but small polyped sediment tolerant corals became common since the early cretaceous late jurassic to cretaceous turbid water coral assemblages are dominated by plocoid or thamnasterioid forms corresponding cainozoic assemblages consist mainly of cerioid and plocoid taxa in fossil twb bioerosion and encrustation are similar or higher than in contemporaneous clear water buildups under higher sediment input accumulation of discrete twb was quenched and level bottoms of both corals and soft substrate biota formed in the resulting coral marls depending on turbidity sedimentation and substrate stability the coral fauna consists largely of both solitary corals and mainly sediment resistant pseudocolonial colonial forms or is dominated by solitary corals many corals show growth anomalies resulting from partial mortality due to episodic rapid sedimentation and unstable substrate in coral marl environments because of terrigenous input nutrient levels probably were elevated yet macroboring and encrustation are very scarce beyond some threshold of terrigenous sediment input and accumulation the ecologic and taphonomic effects of sedimentation and unstable substrate prevail over the effects of nutrient enrichment during the meso cainozoic evolution of scleractinians increasing photoautotrophy and progressive invasion of oligotrophic environments is in contrast to a late cretaceous to cainozoic increase in the relative number of reefs in marginal marine siliciclastic settings this trend may be explained by second order sea level fall and shrinking of epicontinental carbonate seas and isolated platforms driving corals to more narrow attached shelves and by a wider total trophic range in which distinct coral assemblages can thrive as a result of coral evolution and diversification

sedimentary model and high frequency cyclicity in a mediterranean shallow shelf temperate carbonate environment uppermost miocene agua amarga basin southern spain uppermost tortonian to lower messinian temperate carbonates crop out in the agua amarga basin se spain they consist of four units the lower three units can be tentatively assigned to the lowstand systems tract of a fourth order sequence constituting in turn the lowstand megatrough unit transgressive breccia unit and highstand bedded unit stages of a higher order cycle all these materials were deposited in a small pull apart basin related to the sinistral carboneras strike slip fault system the best represented is the bedded unit up to 25 m thick which consists of bioclastic bryozoan bivalve dominated calcarenites calcirudites with abundant fragments of echinoids barnacles benthic foraminifers coralline algae brachiopods and solitary corals facies trends within this unit are roughly arranged in an e w direction with the coastline to the north of the basin the depositional model is that of a gentle ramp with prograding beaches and shoals in its higher parts seaward of the shoals was the factory area where most organisms lived and maximum carbonate production took place from this area some of the skeletons were washed landwards by waves and or currents during storms and incorporated into the shoals and beaches and others moved downslope along the ramp as mass flows accumulating to form the fan bedded zone the factory area and fan bedded sediments intercalate five well defined thick beds of calcarenites fine grained calcirudites they show bar morphologies single or amalgamated or make up sand waves with very consistent tabular cross bedding pointing landwards these beds formed in a very shallow wave current influenced coastal environment the bars and sand waves in the fan bedded zone developed during lowstands while those located higher up in the ramp interbedded with the factory facies are related to transgressive stages prograding beaches shoals factory facies and fan bedded layers developed during the highstands net skeletal production occurred mainly during the highstands sediment accretion values of these sediments are similar to those of present and ancient shallow marine temperate carbonates considering that the whole bedded unit was deposited in a 100 000 year interval equivalent to the short eccentricity cycle the five cycles inside the bedded unit would therefore correspond to the c 20 000 year precession cycles of the milankovitch band

one thousand seven hundred years of interaction between glacial activity and flood frequency in proglacial lake muzelle western french alps local glacial fluctuations and flood occurrences were investigated in the sediment sequence of proglacial lake muzelle based on geochemical analysis and organic matter content established using loss on ignition and reflectance spectroscopy we identified six periods of increased glacial activity over the last 1700 yr each is in accordance with records from reference glaciers in the alps a total of 255 graded layers were identified and interpreted as flood deposits most of these occurred during glacial advances such as the little ice age period and exhibit thicker deposits characterized by an increase in the fine grain size fraction fine sediment produced by glacial activity is transported to the proglacial lake during heavy rainfall events the excess of glacial flour during these periods seems to increase the watershed s tendency to produce flood deposits in the lake sediment suggesting a strong influence of the glacier on flood reconstruction records thus both flood frequency and intensity which is estimated based on layer thickness as a proxy cannot be used in reconstruction of past extreme events because of their variability there is a need to take into account changes in sediment supply in proglacial areas that could preclude satisfactory interpretation of floods in terms of past climate variability

ocean overturning since the late cretaceous inferences from a new benthic foraminiferal isotope compilation 1 benthic foraminiferal oxygen isotopic d 18 o and carbon isotopic d 13 c trends constructed from compilations of data series from multiple ocean sites provide one of the primary means of reconstructing changes in the ocean interior these records are also widely used as a general climate indicator for comparison with local and more specific marine and terrestrial climate proxy records we present new benthic foraminiferal d 18 o and d 13 c compilations for individual ocean basins that provide a robust estimate of benthic foraminiferal stable isotopic variations to 80ma andtentatively to 110ma first order variations ininterbasinal isotopicgradients delineate transitions from interior ocean heterogeneity during the late cretaceous 65 ma to early paleogene 35 65 ma homogeneity and a return to heterogeneity in the late paleogene early neogene 35 0 ma we propose that these transitions reflect alterations in a first order characteristic of ocean circulation the ability of winds to make water in the deep ocean circulate we document the initiation of large interbasinal d 18 o gradients in the early oligocene and link the variations in interbasinal d 18 o gradients from the middle eocene to oligocene with the increasing influence of wind driven mixing due to the gradual tectonic opening of southern ocean passages and initiation and strengthening of the antarctic circumpolar current the role of wind driven upwelling possibly associated with a tethyan circumequatorial current in controlling late cretaceous interior ocean heterogeneity should be the subject of further research