marine geology of sohm basin canadian atlantic margin multichannel seismic reflection seismic refraction and magnetic anomaly data are used to interpret the mesozoic sea floor spreading history and subsequent sedimentary evolution of the sohm basin southeast of nova scotia observed m series mesozoic magnetic anomalies show that oceanic crust in the sohm basin was generated at very slow rates of sea floor spreading 5 15 mm yr half rates the slow spreading created very rough crustal topography but the crustal thickness and seismic velocity structure are typical of normal oceanic basement basement depths corrected for sediment loading fall below the predicted age depth curve in the anomaly m25 m4 interval these depth anomalies and an associated regional negative geoid anomaly suggest that the sohm basin is underlai by asthenosphere denser and possibly colder than normal correlation of seismic reflection profiles in the basin to regional seismic stratigraphy together with age constraints from reflection pinch outs on dated oceanic crust provides a chronology for interpreting the seismic sequences the jurassic to lower cretaceous sequences are similar in thickness and acoustic character to sequences observed along the united states atlantic margin suggesting that the new england seamount chain had little effect on sediment distribution patterns within the early western north atlantic basin upper cretaceous sediments in the sohm basin are thin probably because seaward transport of sediment was restricted by eustatic sea level rise and by a sedimentary ridge uplifted because of salt tectonics along the central and upper continental rise progradati nal sedimentary wedges and erosional unconformities characterize the tertiary and quaternary sedimentary record along the lower continental rise the prograding sequences generally correlate to sea level lowstands repeated episodes of erosion by abyssal currents are marked by seismic unconformities horizon au lower oligocene lm lower miocene mm middle miocene and l upper pliocene the deep currents also controlled local patterns of deposition and modified cross slope sediment transport and accumulation patterns thick supra horizon l sediments cover the sohm basin and reflect rapid sediment influx caused by glacio eustatic fluctuations in sea level during the quaternary

open system coral ages reveal persistent suborbital sea level cycles sea level is a sensitive index of global climate that has been linked to earth s orbital variations with a minimum periodicity of about 21 000 years although there is ample evidence for climate oscillations that are too frequent to be explained by orbital forcing suborbital frequency sea level change has been difficult to resolve primarily because of problems with uranium thorium coral dating here we use a new approach that corrects coral ages for the frequently observed open system behavior of uranium series nuclides substantially improving the resolution of sea level reconstruction this curve reveals persistent sea level oscillations that are too frequent to be explained exclusively by orbital forcing

macroevolutionary history of the planktic foraminifera planktic foraminifera are an abundant component of deep sea sediment and are critical to geohistorical research primarily because as a biological and geochemical system they are sensitive to coupled bio hydro lithosphere interactions they are also well sampled and studied throughout their evolutionary history here we combine a synoptic global compilation of planktic foraminifera with a stochastic null model of taxonomic turnover to identify statistically significant increases in macroevolutionary rates there are three taxonomic diversifications and two distinct extinctions in the history of the group the well known cretaceous paleogene extinction is of unprecedented magnitude and abruptness and is linked to rapid environmental perturbations associated with bolide impact the eocene oligocene boundary extinction occurs due to a combination of factors related to a major reorganization of the global climate system changes in ocean stratification seawater chemistry and global climate recur as primary

sea level change along the italian coast during the holocene and projections for the future published and new sea level data are used to provide projections of sea level change in italy for the year 2100 by adding new isostatic and tectonic component to the ipcc and rahmstorf projections comparison of the observations from more than 130 sites with different geomorphological and archaeological sea level markers with the predicted sea level curves provides estimates of the vertical tectonic contribution to the relative sea level change the results are based on the most recent anu model for the ice sheets of both hemispheres including an alpine deglaciation model on the basis of the eustatic tectonic and isostatic components to the sea level change projections are provided for marine inundation scenarios for the italian coastal plains for the year 2100 that today are at elevations close to current sea level

anatomy of a late quaternary carbonate island constraints on timing and magnitude of sea level fluctuations west caicos turks and caicos islands bwi abstract the data set of the island of west caicos consists of a combination of high resolution lidar and digital imagery radiometric data and amino acid racemization aar d l values as well as extraordinary preservation of sedimentary and bio constructed deposits on the island together with a well established regional stratigraphic framework from the neighboring bahamian island chain and detailed field mapping the west caicos data set provides an opportunity to advance our understanding of the link between carbonate stratigraphy and the controlling parameters of sea level sediment supply tectonics and climate the exceptionally well preserved stratigraphic record of the mid late pleistocene from west caicos allows recognition of marine isotope stages mis 9 11 5e and holocene the west coast of the island provides a continuous 8 4 km exposure of the mis 5e record that enhances our understanding of the intra mis 5e bipartite succession in this region and supports a sea level lowering that occurred during the last interglacial lig west caicos accreted as a series of eolian foreshore shoreface barrier reef and fringing reef facies shoreline positions for all but the mis 7 and mis 5a c deposits are now captured in the sub meter geodetic quality topobathy lidar survey the star town unit of mis 9 11 age forms the southern margin of the island as well as the central karst modified spine with uranium thorium u th coral ages of between 368 and 365 thousand years ago ka and a d l glu average of 0 60 early mis 5e strata include the railroad ridge unit in the center of the island which was previously identified as one of the older units the railroad ridge unit is a north south linear dune ridge that has a d l glu average of 0 52 and indicates the onset of sediment sources from the east associated with a flooded central caicos platform approximately synchronously the early mis 5e south reef unit 3 75 4 m sea level elevation nucleated on the western coast of west caicos attached to the middle pleistocene star town unit the south reef corals yield an average coral u th age of 126 5 ka with an average d l glu from skeletal matrix of 0 46 this transitional barrier fringing reef is unconformably overlain by the late mis 5e boat cove unit corals in the basal transgressive phase of this upper mis 5e boat cove unit yield an average 120 6 ka u th and average d l glu of 0 45 shallow marine foreshore and eolian facies of the late mis 5e rest on a wave cut terrace that cuts the early mis 5e south reef unit by as much as 3 m down to a 0 5 m above present sea level elevation the upper mis 5e boat cove unit displays a maximum of 4 5 m elevation above present day sea level measured from the middle of the foreshore this estimate may be a minimum value as the exposures on the west coast are part of a forced regressive foreshore sequence last stages of the upper mis 5e deposition are seen in a series of regressive dune beach ridge deposits referred to as the northeast ridges unit with sea level positions ranging from 4 5 m early in the central part of west caicos to 0 5 m on the far northeast coast eventually building down below present day sea level this sea level history fits well with previously documented records in the bahamas and globally and the extensive erosion supports a short lived between 126 and 120 ka intra mis 5e relative sea level fall holocene deposition on west caicos is restricted to northern and eastern margins of the island as a combination of strandplain and dune ridge mixed skeletal oolitic units using the high resolution digital elevation model dem and linked digital geologic map makes it possible to compare areas of the different pleistocene and holocene units quantitatively and to constrain volumetric assessments and accumulation rates on the island for different units the peak sediment volume production accumulation rate between 6 5 and 8 106 m3 or between 2 2 and 2 7 106 m3 per ka is observed in the upper mis 5e unit this rate is 5 times greater than the 0 5 106 m3 per ka estimated for the holocene ooid dune ridge strandplain complex suggesting that the combination of higher sea level greater wave and wind energy and warmer ocean temperatures may have fostered the higher rate of chemically precipitated sediment supply

late pleistocene coastal evolution of san giovanni di sinis west sardinia western mediterranean abstract the upper pleistocene succession of coastal deposits outcropping at san giovanni di sinis west sardinia has been studied since the 1960s however the absence of consistent radiometric ages has allowed the production of competing stratigraphic subdivisions of these deposits with different isotopic stage ois mis attributions the succession is composed of sandy to gravelly shallow marine coastal aeolian and alluvial fan plain deposits facies analysis and log correlations show the presence of three unconformities t1 t2 t3 always overlain by shallow marine deposits cutting through the substrate alluvial fan or aeolian sediments we have collected three samples for optically stimulated luminescence osl dating at the top of each shallow marine deposit the succession is composed of four unconformity bounded units u1 u2 u3 u4 and the new osl dates indicate the presence of three different sea level highstands the first unit u1 which is composed of shallow marine to aeolian deposits and overlies transgressive surface t1 is related to a marine transgression during ois 7 186 13 ky unit 2 is composed of continental deposits and formed during ois 6 unit 3 represents ois 5 and overlies a transgressive surface t2 more precisely subunit u3a is related to ois 5e 120 10 ky eu tyrrhenian or eemian sensu strictu and is characterized by shallow marine to aeolian deposits developed during both transgressive and highstand phases the following bay deposits of subunit 3b are associated with ois 5c 100 5 ky and record a second transgressive event t3 and highstand phase occurred during the neo tyrrhenian the succession of san giovanni di sinis ends with continental deposits of unit 4 associated to a sea level fall that took place at the beginning of the last glacial phase ois 4

geomorphology stratigraphy and facies analysis of some late pleistocene and holocene key deposits along the coast of sardinia italy and geochronology for some key sites along the coast of sardinia italy a note from the editor in chief

nannoplankton origination events and environmental changes in the late paleocene and early eocene the origination of six nannoplankton species in the late paleocene to middle eocene involves significant change in the entire nannofossil assemblage the change began at the first occurrence and accelerates at the increase in abundance of the new species the changes in the environment generally reflect the preferred ecology of the originating species the species that originated in the late paleocene to early eocene outside of the paleocene eocene thermal maximum petm are generally thought to be oligotrophic taxa adapted to warm water conditions during this long interval temperatures were generally increasing and nutrient availability was decreasing conditions that would have been advantageous for the originating taxa conversely the species that originated in the middle eocene are generally thought to be mesotrophs adapted to colder water conditions these taxa were selected for during a time of generally increasing nutrient availability and decreasing temperature orbital stratigraphy indicates that the first occurrences of three paleocene taxa are time transgressive by up to 400 kyr the only event that appears to be synchronous is the abundance increase of zygrhablithus bijugatus during the petm this species is thought to be mesotrophic and replaces the genus fasciculithus at a time when nutrient availability was likely increasing rapidly

mis 5e at san giovanni di sinis sardinia italy stratigraphy u th dating and eustatic inferences the most representative late pleistocene tyrrhenian outcrop in sardinia san giovanni di sinis was re visited based on detailed sedimentological and stratigraphical analysis supported by u series dating of fossil corals the stratigraphy shows shorefaceebackshore sandstones overlying an erosional surface cut on vertebrate bearing layers facies analysis and sequence stratigraphic approaches suggest eustatic changes during the overall depositional interval of the marine sequence disconformities distinguish two coastal units suggesting a lateral shifts of the depositional environments driven by millennial scale frequency sea level fluctuations never exceeding a maximum height 1t o 3 m and by a subsequent rise to 5 o 5 5 m asl these deposits have historically been assigned to mis 5 on the basis of i their palaeontological content warm senegalese fauna ii lithostratigraphic interpretations and iii amino acid geochronological data and generally attributed to the high sea level episode of mis 5e sub stage through sequential interpretation u series measurements in colonies of cladocora caespitosa from the main outcrop of san giovanni di sinis and other minor deposits from the eastern side of the isthmus and from

middle pleistocene to holocene coastal evolution of nw sardinia mediterranean sea italy abstract the middle pleistocene holocene sardinian stratigraphy has been revised to identify the roles played by sea and climate changes in controlling sedimentation the succession dated through optically stimulated luminescence quartz k feldspar and 14 c the most recent was grouped into eight major stratigraphic units mainly represented by coastal dunes shallow marine and alluvial systems these units range in age from mis 8 300 ka to mis1 6 ka little information is available for the period between mis 8 and 6 the available data however allow some comments on climate changes over the last 125 ka the last interglacial mis 5 is subdivided into five substages e a mis5e eemian is considered the climate optimum of this interglacial sea level was 4 6 m higher than today and climate conditions were warmer and more humid mis 5c is the second high stand peak sea level was about 1 5 m above the modern level and paleoclimatic and paleogeographic conditions were similar to the present during mis 4 at the beginning of the glacial phase a climatic deterioration occurred temperatures dropped by 6c relative to mis 5e in about 5 ka and sea level fell about 60 m this led to a progressive disruption of inland vegetation cover and to repeated valley slope denudation the sea level fall created the accommodation space for fan development in sheltered and cliffed areas where debris flows developed and filled almost completely the terminal parts of the narrow coastal valleys coves in wider areas however coastal dune fields developed contemporaneous presence of alluvial fan and dune systems is associated with the local morphology that could mitigate or amplify moist conditions within a generally arid environment during mis 3 several climate fluctuations occurred wet arid d o h events however the shallow sardinian shelf was continuously sufficiently exposed to become the source area of bioclastic sands these sands were blown inland and formed extensive dunefield systems dunes dominated the west coasts of sardinia under cold and relatively dry conditions in some areas these dunefield systems were eventually almost completely dismantled and reworked into water flow dominated alluvial fans by catastrophic rainfall events thus the local climate quickly switched from arid to humid conditions no record of the last glacial maximum deposits mis 2 was observed along the nw sardinian coast during the holocene transgression mis1 coastal dune systems developed and progressively migrated inland and temperature rose to reach the present day condition

uplifted flank margin caves in telogenetic limestones in the gulf of orosei central east sardinia italy and their palaeogeographic significance abstract this work reports the results of geomorphological observations carried out in the coastal fico cave and surrounding areas baunei central east sardinia in the gulf of orosei a tidal notch generally believed to be of eemian mis 5e age is barely visible at 8 5 above present sea level asl some metres below the main entrance of the cave old cave passages now partially opened by cliff retreat and parallel to the coastline are clearly visible at around 14 m asl and correspond to the main level of fico cave two more notches are located higher at 22 and 50 m asl fico cave itself is composed of at least 6 clearly distinguished more or less horizontal levels 10 m below present sea level bsl and 14 22 40 50 and 63 m asl independent of the stratal dip arguing for a sea level and hence fresh water lens control cave passages develop along main fractures more or less parallel to the coastline and never extend landward for more than 150 m mostly ending blindly or diminishing in their dimensions progressively landward most passages only contain clay deposits lacking fluvial or marine sediments or typical fluvial erosion morphologies i e scallops it is suggested from this body of evidence that fico cave was formed in the coastal mixing zone along major discontinuities during several quaternary interglacial periods when sea level was high and relatively stable for enough time to develop large dissolutional voids the geomorphological observations indicate the main 14 m asl level of the cave to have formed during mis 9 and was heavily reworked during mis 5 while the higher levels are relative to older interglacial highstands that occurred between 1 ma and 325 ka the small active branch developed below present sea level has formed during mis 7 225 ka these observations shed new light on the position of the mis 5e highstand markers in this area of the coast much higher than previously thought

size patterns of the coccolith watznaueria barnesiae in the lower cretaceous biotic versus abiotic forcing abstract body size is a major trait allowing the assessment of the respective control of evolution vs palaeo environment on unicellular micro organisms size patterns can be retraced for fossilisable micro organisms especially for coccolithophores over geological time spans here we present coccolith size patterns of watznaueria barnesiae which was a dominant and ubiquitous taxon in the mesozoic measurements were conducted at two sites spanning the upper berriasian to lower hauterivian namely the vergol la charce section in the epicontinental vocontian basin and the odp leg 185 hole 1149b located in the nadezhda basin in the pacific ocean the obtained results were treated using multivariate analysis in order to detect significant trends of the measured parameters size values of coccoliths from both sites are remarkably similar and display comparable patterns namely a statistically significant increase in the lower valanginian until maximum sizes recorded in the aftermath of the weissert event upper valanginian although w barnesiae coccolith size fluctuations in the short term might be related to environmental changes the observed long term size patterns are interpreted as the result of directional selection in which a single phenotype is favored through time comparison with data available in the literature shows a return to a smaller size after the turonian

size variation of conodonts during the smithian spathian early triassic global warming event the early triassic smithian spathian boundary ssb crisis coincided with an episode of extreme warmth a high resolution stratigraphic framework comprising six conodont zones is provided in the jiarong section nanpanjiang basin in south china detailed size measurements of 441 conodont elements of the closely related genera neospathodus triassospathodus and novispathodus show for the first time that this clade suffered a temporary but significant size reduction during the ssb crisis the size reduction of conodonts was probably caused by an episode of global warming

taxonomic evolution of neogene planktonic foraminifera and paleoceanographic relations the taxonomic evolution of neogene 24 ma to present day planktonic foraminiferal species are described using four indices rate of speciation rate of extinction rate of diversification and rate of turnover the evolution of neogene planktonic foraminifera is marked by three principal stages 1 a diversification stage 24 to 16 ma early miocene 2 an equilibrium stage 16 to 5 ma middle and late miocene and 3 a declining stage 5 ma to recent pliocene and quaternary the early miocene diversification was in response to an increase in polar to equatorial thermal gradients and related subdivision of surface water masses during the middle and late miocene the assemblages remained close to their equilibria with relatively low diversification rates the decline in diversity during the pliocene and quaternary probably resulted from adverse effects imposed by both large scale paleoceanographic fluctuations that began about 6 ma and high frequency climatic oscillations related to northern hemisphere glaciations and deglaciations that began at about 2 5 ma bursts of evolutionary activity marked by higher rates of turnover coincided with major paleoceanographic changes average evolutionary rates appear to be similar for tropical transitional and temperate assemblages although the actual numbers of extinctions and speciations are higher in tropical assemblages because of higher standing diversity contemporaneity of turnover peaks in the three climatic regimes indicates global control of paleoceanographic perturbations upon planktonic foraminiferal evolution the observed evolutionary pattern supports the stationary model of stenseth and maynard smith 1984

seismic stratigraphic framework and depositional history of a large upper cretaceous and cenozoic depocenter off southwest nova scotia canada abstract interpretations of the late cretaceous to quaternary geological history of the north american basin rely on a seismic and lithostratigraphic framework developed predominantly from data along the northeastern united states margin prior to this study attempts to extend this framework northward to the nova scotia margin were hindered by correlation issues across seamounts limitations in data coverage and significant complications caused by widespread canyon erosion and shallow salt structures these challenges are overcome using modern seismic reflection data along the southwestern nova scotia margin in the shelburne sub basin where upper cretaceous through quaternary sequences manifest four distinct phases in the interplay between down slope and along slope depositional and erosional processes the first phase spanning the late cretaceous to late eocene is characterized by widespread periods of gully erosion interspersed with periods of pelagic and hemipelagic carbonate rich sedimentation extensive failure of upper slope regions related to the montagnais meteorite impact also occurred during this time the second phase spanning the oligocene to late miocene is dominated by widespread erosion deposition by gravity flow processes and sediment re working by bottom currents marked erosion and or non deposition along the mid to lower slope is attributed both to down slope and along slope processes the third phase spanning the late miocene to late pliocene is dominated by bottom current deposition including stacked sequences of giant sediment waves and large contourite drifts along the slope the final phase from the late pliocene to present exhibits a return to predominance of down slope gravity flows with deposition focused below the upper slope this four phase history of depositional and erosional processes is similar to that documented south of the study area along the u s margin

sea level changes and past vegetation in the punic period 5th 4th century bc archaeological geomorphological and palaeobotanical indicators south sardinia west mediterranean sea abstract the ancient shorelines and main differences in the vegetational landscape of s sardinia during the punic period 5th 4th century bc have been recognized by an interdisciplinary archaeological paleobotanical and geomorphological approach sixteen trading amphoras and one olla of punic manufacture brought to light during underwater exploration in santa gilla lagoon s sardinia w mediterranean provide data on relative sea level changes the infilling mud of each retrieved amphora is representative of the ages lasting for about 200 300 years the macro archaebotanical contents document the use of seeds and fruits of vitis sorbus ficus olea and prunus during punic trading and suggest the occurrence of agro pastoral practices in the surrounding plains or the area behind the lagoon system the palynological analysis documents the presence of holm and cork oak forests a widespread mediterranean forest with juniper and pinus and a developed stagnant coastal system and reveals a climate induced past vegetation change that is likely to have been emphasized by anthropogenic pressure and agriculture activity during the 4th century bc the gps localization of the amphoras shows a distribution according to curved alignments that probably correspond to the shorelines 5th 4th century bc at 1 95 10 m and 1 70 10 m geomorphological data reveal a sea level rise of about 25 cm during a century corresponding to 300 m of shoreline regression towards the alluvial plain with these rapid processes of drowning of the coastal plain the presence of punic settlements along the lagoon borders documents the reorganization of commercial and economic activities this shows the great adaptability of the ancient population to the sea level rise slr and fast flooding processes of the coastline in a lagoonal area vulnerable to subsidence phenomena

global climatic forcing of deep sea benthic foraminiferal test size during the past 120 m y stratigraphic distribution of the maximum diameter of the largest deep water 1500 m water depths calcareous trochospiral benthic foraminiferal tests in samples representing the past 120 m y shows that average values of the maximum diameter have doubled since early cretaceous time fluctuations in test size show six minima and six maxima it is significant that the fluctuations correspond to changes in global climate and in deep water dissolved oxygen conditions this latter synchronism indicates that deep sea foraminiferal test size was likely controlled by fluctuations in the level of dissolved oxygen or related factors in the deep ocean caused by global climatic changes

approximate paleomagnetic poles for some of the new england seamounts abstract paleomagnetic pole positions were estimated for several of the new england seamounts by a simple dipole method computer poles are in agreement with poles determined by others for several seamounts in the chain using three dimensional modeling collectively the poles plot in a swath which follows the late mesozoic polar wander path across northern siberia to the bering strait it is shown that for relatively simple seamount geometries and dipole like magnetic anomalies inclinations and declinations determined by the dipole method agree within a few degrees with those found by three dimensional methods paleopole determinations by either method may be degraded by interfering neighboring anomalies and other effects but the five poles considered best determined are consistent with the overall distribution of poles the distribution is not consistent with a model involving a hot spot origin or with geologic evidence suggesting origin during a brief time within the cretaceous normal interval statistically the poles are in much better agreement with the hypothesis that the seamounts are the same age as the sea floor underlying them

sea level and climate changes during ois 5e in the western mediterranean palaeontological geomorphological and sedimentological data supported by isotopic dating on oxygen isotopic stage ois 5e deposits from the spanish mediterranean coast are interpreted with the aim of reconstructing climatic instability in the northern hemisphere data point to marked climatic instability during the last interglacial ois 5e with a change in meteorological conditions and consequently in the sedimentary environment the oolitic facies generated during the first part of ois 5e ca 135 kyr shift into reddish conglomeratic facies during the second part ca 117 kyr sea surface temperature sst and salinity are interpreted mainly on the basis of warm senegalese fauna which show chronological and spatial differential distribution throughout the western mediterranean present hydrological and meteorological conditions are used also as modern analogues to reconstruct climatic variability throughout the last interglacial and this variability is interpreted within the wider framework of the north atlantic record all the available data indicate an increase in storminess induced by an increase in the influence of northwesterlies a slight drop of sst in the northern western mediterranean and an important change in meteorological conditions at the end of ois 5e 117 kyr these changes correlate well with the decrease in summer insolation and with the climatic instability recorded in north atlantic high latitudes

a new conceptual model for the structural evolution of a regional salt detachment on the northeast scotian margin offshore eastern canada in this study we examine using seismic data in conjunction with numerical modeling a regional scale salt detachment and associated synkinematic sediments from the scotian margin offshore eastern canada this part of the scotian margin is characterized by an up to 4 5 km 2 8 mi thick and approximately 175 km 108 mi long synkinematic wedge of jurassic sediments with internal sigmoidal landward dipping reflectors the synkinematic wedge is laterally extensive encompassing an area of approximately 30 000 km2 11 600 mi2 and soles into an interpreted salt detachment the jurassic synkinematic wedge which is interpreted to have formed as an open ended allochthonous salt nappe was loaded by prograding sediments during the jurassic this loading squeezed the salt seaward and caused the overlying sediments to undergo extension and gravity spreading and gliding detaching on the salt sheet the open ended nappe model provides a mechanism for producing a large amount of extension with very little compensating contraction numerical model results indicate that high rates of extension detaching on even a thin salt layer can result in similar sigmoidal landward dipping strata based on the numerical modeling and seismic interpretation results we propose a new conceptual model for the jurassic paleogene structural evolution of the study area this model may also have implications for other passive margin salt basins with regional salt detachments

u series measurements in tyrrhenian deposits from mallorca further evidence for two last interglacial high sea levels in the balearic islands the campo de tiro type section for the tyrrhenian ecostratigraphic beds of the balearic islands shows four indurated littoral conglomerates and beach rocks unconformably superimposed the lower two units 1 and 2 are separated by a thin layer of reddish continental silts both contain a typical eutyrrhenian fauna whereas a neotyrrhenian fauna characterizes the overlying units 3 and 4 thu measurements by thermal ionisation mass spectrometry on mollusk shells from these deposits yielded ages of 135 ka unit 1 117 ka units 2 and 3 and a scatter of ages around 100 ka unit 4 the stratigraphic relationships and thu data indicate i that uranium was uptaken by mollusks shells but arca sp each time during a relatively short early diagenetic interval before cementation ensured a fair closure of the radioactive system ii two high sea stands characterized the last interglacial isotopic substage 5e of the balearic islands area iii the duration of this episode was 17 ka and iv the change in faunal assemblages and disconformity observed between units 2 and 3 are due to fluctuations in sea level and surface water conditions which occurred during the second high sea level episode of the last interglacial

chronostratigraphic confirmation of mis 5 age of a baymouth bar at is arenas cagliari italy in 2005 the national geological survey of italy released the new sheet 557 cagliari 1 50 000 scale a coastal barrier marine formation at is arenas cagliari sardinia italy containing strombus bubonius was reassigned a holocene age in contradiction with extensive literature published over the past century indicating an mis 5 5 age in 2007 spurred by this controversy a short note was published in il quaternario demonstrating the stratigraphic difficulties in attributing the age of this formation to the holocene later another paper signed by numerous italian geologists was published in il quaternario criticizing the holocene attribution the tectonic consequences of assigning a holocene age to these deposits are of great significance as their elevation could only be explained by strong uplift over the past few thousand years such a tectonic setting would imply a radical change in the recent geodynamic history of sardinia which is considered to be among the most stable areas of the mediterranean basin this paper provides further geochronological data for a mis 5 age for the deposits at is arenas electron spin resonance esr analyses were performed on 4 fossil shells sampled along the fossil baymouth bar the results established an mis 5 age the amino acid racemization aar and u series data that first determined a correlation with the last interglacial tyrrhenian age of this ancient shoreline is reviewed with additional documentation provided by the fossil marker s bubonius

tyrrhenian coastal deposits from sardinia italy a petrographic record of high sea levels and shifting climate belts during the last interglacial isotopic substage 5e abstract detailed petrographic and sedimentological analysis of tyrrhenian coastal deposits from four sites in sardinia provides new data about climate and sea level changes during the early part of the last interglacial isotopic substage 5e and shows that facies analysis is not only useful for the identification of ancient depositional environments but also represents a powerful tool for evaluating past climatic conditions and sea level forcing mechanisms two shallowing upward sequences sensu ward w c brady m j 1979 strandline sedimentation of carbonate grainstones upper pleistocene yucatan peninsula mexico am assoc pet geol bull 63 362 369 commonly separated by an erosion surface and displaying complex geometric relationships occur above modern sea level at several locations along the shorelines of sardinia these sequences include upper shoreface to backshore deposits and were formed during separate sea level highstands attributed to isotopic substage 5e our recent revision of these deposits indicates that each sequence presents distinctive petrographic characteristics the older succession essentially contains mixed calcarenites rich in quartz grains and lithic fragments whereas the younger sediments are dominated by carbonate bioclasts such as red algae coral and mollusk fragments both units apparently accumulated in a similar depositional setting but during different climatic regimes the petrography of the lower unit reflects a temperate humid period characterized by increased weathering and continental erosion whereas the composition of the upper one suggests a dryer and possibly warmer climate favoring active carbonate production the disparity in petrographic composition between sequences probably records the migration of atmospheric circulation cells i e a shift of climate belts before and after the 128 ka insolation maximum our climatic data are coherent with the calculated insolation curves for isotopic substage 5e and thus support the milankovitch hypothesis for the origin of pleistocene climates in contrast our sedimentological data clearly show the occurrence of two distinctive highstands of sea level during this time period which does not agree with the hypothesis it follows that the relation between orbitally induced insolation variations climate and sea level is not necessarily straightforward

geomorphic evidence of major sea level fluctuations during marine isotope substage 5e cape cuvier western australia abstract a detailed geomorphologic and morphostratigraphic investigation of raised marine terraces at cape cuvier western australia reveals two morphologically distinct units a lower well developed accretional reef terrace between 3 and 5 5 m above mlws mean low water springs hereafter denoted as represents an extended interval of stable sea level an upper erosional terrace and incipient coralgal rim between 8 5 to 10 5 m represents a brief sea level stillstand at this higher elevation these features suggest the lower and upper terraces developed during discrete sea level events in an attempt to better define the timing of emplacement of each marine unit 20 coral samples collected along vertical and lateral reef growth axis from both terraces were analysed with u series dating unfortunately all coral samples exhibited elevated 234 u initial values suggesting that pervasive uptake of 234 u enriched uranium and 230 th thorium had occurred despite the shortcomings of absolute dating a succession of events can be resolved though morphostratigraphic relationships comparison of the facies relationships coral growth and morphostratigraphic features between the lower and upper terraces indicates that an early to mid mis 5e stillstand at 3 to 5 m was followed by a late rise to 8 5 to 10 5 m this agrees with an emerging global view of mis 5e sea level history derived from stable carbonate platforms rejecting the hypothesis that these higher sea level benchmarks are an artefact of localized tectonic processes

geochronology for some key sites along the coast of sardinia italy recent stratigraphic surveys and facies analyses have questioned long held interpretations of the development and furthermore the age of quaternary sediments along the coast of sardinia the matter of debate is whether the investigated sediments were deposited during the late wurmian and holocene or during marine isotope stage mis 5 and older stages optically stimulated luminescence standard blue optically stimulated luminescence osl post infrared ir pulsed blue osl and post ir infrared stimulated luminescence irsl dating was applied to shallow marine and aeolian deposits as well as radiocarbon dating to bulk organic material in palaeosols radiocarbon dates suggest sedimentation during the late wurmian and holocene whilst the luminescence results for both quartz and potassium feldspar indicate a depositional age for most of the investigated sites prior to and during mis 5 from a geochronological point of view the luminescence ages are considered reliable because they passed all quality tests furthermore there is good agreement of two dosimeters with different bleaching and luminescence properties the radiocarbon ages might suffer from underestimation due to some contamination with young carbon which however cannot be large enough to yield such young ages

a probabilistic assessment of sea level variations within the last interglacial stage robert e kopp 1 frederik j simons 2 jerry x mitrovica 3 adam c maloof2 and michael oppenheimer2 4 1department of earth and planetary sciences and rutgers energy institute rutgers university piscataway nj 08854 usa e mail robert kopp rutgers edu 2department of geosciences princeton university princeton nj 08544 usa 3department of earth and planetary sciences harvard university cambridge ma 02138 usa 4woodrow wilson school of public and international affairs princeton university princeton nj 08544 usa

a reappraisal of the dwarfed mammoth mammuthus lamarmorai major 1883 from gonnesa south western sardinia italy the gonnesa quaternary deposits have been cited since the end of the 19th century due to the discovery during the construction of a railway of an incomplete postcranial skeleton belonging to an endemic dwarfed elephant afterward described by major as a new species elephas lamarmorae major 1883 although the remains have since been reported in the literature as coming from the aeolian deposits outcropping at funtana morimenta the precise provenance of the findings and their chronostratigraphical setting remained uncertain taking into account the route of the now disused railway the stratigraphical successions of the morimenta area and the fact that the elephant bones were actually collected during a number of excavations spanning several decades the location of the fossiliferous site is most likely on the northeast end slope of guardia pisano hill gonnesa where aeolianites correlate with the funtana morimenta formation fmf outcrop the fmf is supposed to predate the onset of the mis 5e climatic event and the tyrrhenian panchina overlies equivalent deposits cropping out along the gonnesa gulf coast therefore the hypothesis that the elephant remains found in the morimenta area were retrieved from late middle pleistocene deposits cannot be ruled out the anatomical features of the bones suggest they represent a single individual perhaps partially exposed and damaged before the discovery new evidence including a thus far unpublished tusk fragment from the guardia pisano hill gonnesa whose schreger angles fall within the range of mammuthus supports the systematic attribution of the incomplete morimenta skeleton to a dwarfed mammoth the size reduction of this sardinian dwarfed mammoth is discussed in light of body mass changes undergone by insular endemic elephants

luminescence dating of interglacial coastal depositional systems recent developments and future avenues of research abstract luminescence dating offers new opportunities to explore the evolution of quaternary marine coastal facies and landforms this review highlights the main advances in luminescence geochronology of interglacial coastal sediments through the analysis of 547 luminescence ages most of which were published during the last decade the majority of these reported luminescence investigations have been carried out along passive margin coasts since the turn of the century the discovery of a normalization procedure known as single aliquot regeneration sar has drastically reduced data scatter and improved precision with the consequence that quartz sar optically stimulated luminescence osl has become the dating protocol of choice for the last interglacial lig period a more complex technique known as thermally transferred osl tt osl is presumably proposed for dating older interglacials of the mid pleistocene and beyond feldspar luminescence is increasingly being applied to dating pleistocene sea level high stands due to a much higher dose saturation level than quartz osl the use of feldspar irsl infrared stimulated luminescence is limited by the occurrence of variable but ubiquitous anomalous fading af following the advent of af correction methods several middle pleistocene sites have been amenable to dating albeit with significant related uncertainties recently new protocols involving the measurement of post ir irsl at elevated temperatures have yielded relatively coherent ages for interglacial sediments up to ca 300 ka quartz osl tt osl af corrected irsl and post ir irsl ages are generally correlated with periods of sea level high stands a few ages are reported from the early and middle part of the middle pleistocene as mis11 9 and more commonly mis7 high stands are documented in strongly uplifting active margin coasts however by far the most obvious age peak corresponds to the end of the lig the mis5e shoreline is probably the most studied and luminescence dated coastal feature of all as the chronology of the sea level markers is crucial to assess global eustatic sea level variations through the course of the last interglacial nevertheless the observed abundance of young 100 120 ka luminescence ages for presumed mis5e sediments may underline methodological issues and or reflect the higher preservation potential of late regressive sequences on the other hand the occurrence of geographically distant reports of mis5a high stand might reflect a true eustatic origin for this event age analysis supports the impression of general reliability of luminescence for the timing of former sea level high stands there is a clear need to address issues in dose rate variability in the phenomenology of fading in feldspar and in the behaviour of luminescence growth with dose both in laboratory and natural conditions these could be addressed and properly evaluated by dating different minerals as multiple or single grains with consequent variable internal dose rates more robust practices in the application of luminescence dating techniques could eventually constrain the age uncertainties to no better than 2 3 therefore the strength of luminescence as a dating tool is more in terms of its extended age range and the ubiquity of datable material

thirteen thousand years of southeastern mediterranean climate variability inferred from an integrative planktic foraminiferal based approach over the past 13 ka the hydrology for the southeastern mediterranean was mainly regulated by nile river runoff which in turn was controlled by climate forcing being affected by orbital forcing and the position of the intertropical convergence zone itcz planktic foraminiferal data assemblages stable isotopes and size properties indicate three major periods 1 from 13 0 to 11 5 ka the upper water column was well mixed cold and productive 2 from 11 5 to 6 4 ka hydrology and foraminifers were affected by intensified monsoonal circulation the enhanced size of globigerinoides ruber is interpreted as a response to environmental stress caused by low saline waters 3 after 6 4 ka the southward retreat of the itcz caused a decrease in freshwater discharge and hence a return to ecological equilibrium a drop in foraminifer diversity from 2 9 to 1 1 ka was related to more arid conditions and limited supply of nutrients from the nile river we suggest a link to a negative north atlantic oscillation nao marking the roman humid period in the western mediterranean and in anti phase with the southeastern mediterranean aridity because nile river runoff exerted major control on surface hydrology a connection to indian and pacific climate systems partially controlling precipitation over the nile catchment area is hypothesized from 1 1 to 0 54 ka high foraminifer diversity indicates humid conditions synchronous to the medieval climate anomaly under a positive nao state over the past 0 54 ka encompassing the little ice age another arid period is indicated by a drop in foraminifer diversity

climate changes and human impact on the mistras coastal barrier system w sardinia italy abstract integrated archaeological and geological studies conducted on mistras coastal barrier system of central sardinia showed that it developed as transgressive systems during the final stages of the holocene sea level rise final stage of the holocene climate optimum about 6300 6000 cal y bp and become regressive prograding from about 2500 cal y bp when sea level reached the present elevation the regression of the coast was however not continuous but characterized by distinct transgressive regressive phases t r associated to precise climatic fluctuations tied with global eustatic and climatic phases the first regression occurred between 2500 and 1900 cal y bp this time interval known as roman warm coincides with the phoenician punic and roman attendance of the west sardinia coast at that time areas close to the coastal cities had to host landings and perhaps ports probably located at short distance from the shoreline archaeological excavations and findings have documented that in the mistras area punic constructed a long boulder structure probably dated from the 4th century bce to better protect an incipient lagoon used as the harbour of the city of tharros this had the effect to modify the normal behaviour of the beach system that transformed from spit to barrier lagoon during the second regressive phase the well established beach lagoon system developed quasi continuously for 1200 y 650 and 1850 ce this progradation started during a new warm period medieval and continued favoured by gentle sea level fall occurred during the cold little ice age time during this time after the abandonment of the city of tharros and of the sinis peninsula the mistras area was poorly populated as consequence there was no more an active harbour and large sandy dunes developed and nourished the shore allowing a no man influence progradation of the coast the third stage is the current one and begun about 165 y ago post 1850 ce after the relative sea level rise occurred after the end of the little ice age geological and archaeological data of western sardinia barrier lagoon systems revealed that the mistras barrier lagoon evolution was human influenced since the punic time the study pointed that little human activities on the coast could influence its natural behaviour and landscape and that little climatic changes both positive and negative can induce progradation or erosion of the system as well

millennial submillennial scale sea level fluctuations in western mediterranean during the second highstand of mis 5e abstract thispaperinvestigatesaseriesofsmall scale short lived uctuationsofsealevelregisteredinaprogradingbarrierspit thatgrew during the mis 5e this interglacial includes threehighstands zazoet al 2003 andwe focus on the second highstand of assumed duration 10 2 ka given that ueth ages do not providemoreaccuratedata geometryand3darchitectureofbeachfacies andthin sectionpetrographywereusedto investigate eight exposed of apping subunits separated by seven conspicuous erosion surfaces allinterpreted as the result of repeated small scale uctuations of sea level each subunit records a relatively rapid rise of sea level that generated a gravelly shoreface with algalbioherms and a sandy uppermost shoreface and foreshore where most sand accumulated a secondrange of still smaller scaled oscillations of sea level has been deduced in this phase of sea level uctu ation from lateral and vertical shifts of the foreshore plunge step uppermost shoreface facies eventually progradation with gently falling sea level took place and foreshore deposits underwentsuccessive vadose cementation and subaerial dissolution owing to relatively prolonged exposure laterrecovery of sea level re established the highstand with sea level at approximately the same elevation and there began deposition of a new subunit the minimum sea level variation fall and subsequent rise required to generate the observed features is 4 m the time span available for the whole succession ofevents and comparison with the holocene prograding beach ridge complex in the nearby roquetas almeria were used to calculate the periodicity of events a millennial suborbital time scale is suggestedfor uctuations separating subunits and a decadal scale for the minor oscillations inside each subunit 2010 elsevier ltd all rights reserved

late cretaceous cenozoic development of outer continental margin southwestern nova scotia the growth pattern for the outer continental margin of nova scotia during the late cretaceous and cenozoic was studied using seismic stratigraphy and well data sediment accumulation was broadly controlled by temporal changes in relative sea level but significant spatial and temporal changes in accumulation patterns were caused by changes in sediment supply rate morphology erosion by abyssal currents and salt tectonics a jurassic early cretaceous carbonate platform remained exposed until the late cretaceous and controlled the location and steepness of the paleoslope until the late miocene local erosion of the outer shelf and slope in the late paleocene early eocene produced chalky fans on the upper rise the relationship between erosion of the shelf in the late eoce e and early oligocene and abyssal current erosion of the upper rise in the oligocene is unclear seaward extensions of tertiary shelf edge canyons are poorly defined except for the eocene fans in the miocene abyssal currents eroded a bench on the upper continental rise subsequently sediments lapped onto and buried the paleoslope the lower rise above horizon au oligocene is composed of fans and olistostromes shed from halo kinetic uplift of the upper rise current eroded unconformities are common in the rise sequence but the only current deposit is a pliocene interval 300 m restricted to the lowermost rise pleistocene turbidity currents eroded the present canyon morphology

raised marine sequences of lanzarote and fuerteventura revisited a reappraisal of relative sea level changes and vertical movements in the eastern canary islands during the quaternary abstract systematic mapping and morphosedimentary analysis of fuerteventura and lanzarote islands supported by laboratory techniques u series mostly by tims 14c analysis and allo isoleucine measurements on biogenic carbonates from raised marine deposits paleomagnetic and a few k ar measurements on volcanic formations related to marine deposits provide a basis for constraining the age of late cainozoic marine units the most complete sequences of raised marine terraces are found at similar elevations in both islands they include up to 12 marine terraces episodes at elevations between 0 m and 70 m above mean sea level asl at least six terraces should be of quaternary age and more recent than 1 2 myr throughout the whole marine sequence with the exception of the holocene terrace the warm fauna assemblage is characterized by the presence of ostrea virleti nerita emiliana and strombus s cf coronatus s cf bubonius however there is a major change highlighted by the disappearance of the first two species below the 8 10 m terrace that could possibly correspond to mis 11 k ar measurements allow an estimate for mean uplift rate of 1 7 cm ka during the last million years the present elevation of the last interglacial deposits about 1 and 2 m asl shows discontinuous vertical movements with possibly a reverse trend since mis 9 in eastern canary islands

mis 5a and mis 3 relatively high sea level stands on the hatay samandag coast eastern mediterranean turkey abstract the coastal belt of hatay samandag in the east mediterranean is marked by the intersection of the african arabian and eurasian anatolian platelet plates where several quaternary shorelines related to relative sea level changes can be seen above the current sea level in this study the most common and best preserved high sea level markers of the marine isotope stage mis 5 and mis 3 shorelines were dated for the first time using the mollusc based electron spin resonance esr method as a result of this research the age of the late mis 5 and mis 3 sea level highstands in the eastern mediterranean the elevation of the corresponding shoreline at samandag coast and the vertical component of the late quaternary tectonic movements which has an impact on shoreline were determined the shorelines at 48 43 m elevations between cevlik and samandag at 58 6 m in tekebasi and at 21 m at keldag have been dated to approximately 72 ka and therefore are correlated with mis 5a the shoreline at 40 39 m elevations between cevlik and samandag has been dated to approximately 53 ka and therefore is correlated with mis 3 according to the position of the mis 5a shorelines the uplift rate over the last 72 ka was 0 88 mm y between cevlik and samandag 1 08 mm y in tekebasi and 0 56 mm y in keldag yielding a 0 84 mm y average this rather fast uplift appears to be related to the vertical component of the strike slip active faults in the samandag antakya fault zone

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

pleistocene raised marine terraces of the spanish mediterranean and atlantic coasts records of coastal uplift sea level highstands and climate changes detailed geological mapping morphostratigraphic palaeontological and geochronological uranium series analyses were undertaken on the raised marine terraces and interbedded terrestrial deposits along the spanish peninsular and insular atlantic and mediterranean coasts several sets of pleistocene shallow marine to coastal deposits exposed in a staircase arrangement are interpreted as being emplaced during sea level highstands coeval with interglacials or interstadials correlating with marine oxygen isotopic stages ois 5a 5c 5e 7 9 11 and older up to three highstands have been identified in deposits formed during ois 5e close to the end of ois 5e there is a record of sudden changes in sea surface conditions and climate marked by the disappearance of a major proportion of the warm senegalese fauna switches from oolitic to non oolitic facies and accumulation of boulder beaches dating of the coral cladocora caespitosa found in a layer that also contains strombus bubonius confirms the occurrence of warm fauna in the mediterranean basin during ois 7 as previously suggested by hillaire marcel et al 1986 goy et al 1986a b zazo and goy 1989 also the occurrence of warm faunas in deposits corresponding to an older interglacial probably ois 9 or 11 in the balearic islands suggests similar oceanographic conditions sea surface temperature assuming constant salinity during the last interglacial and at least two interglacials of the middle pleistocene in the western mediterranean a 2002 elsevier science b v all rights reserved

a review of possible eustatic isostatic and tectonic contributions in eight late holocene relative sea level histories from the mediterranean area abstract this paper consists of a comparison between eight late holocene sea level histories investigated by the author in different mediterranean areas and sea level predictions in the same areas made by global isostatic models the areas include three regions that are generally considered as tectonically relatively stable 1 the southern coast of france 2 sardinia and 3 the southern coasts of tunisia where late holocene evidence may be either of submergence or of emergence also considered are 4 a subsidence region in the northern adriatic and actively uplifting areas 5 in calabria and 6 in nisyros island greece lastly case studies in areas affected by repeated coseismic vertical displacements include 7 western crete and antikythira island in the hellenic arc and 8 the levant coasts of turkey syria and the lebanon in each case the question of whether the evidence available may or may not be consistent with gradual isostatic or eustatic displacements has been explored it appears that in non tectonic areas the hydro isostatic effects have been overestimated sardinia or underestimated southern tunisia by the same models in the northern adriatic the closest mediterranean area to the former scandinavian ice sheet glacio eustatic effects are suspected to be almost absent our analysis failed to quantify isostatic effects in areas of rapid tectonic uplift calabria and nisyros but rejected predictions of significant isostatic subsidence in the hellenic arc and on the levant coast finally several data from tectonic and non tectonic areas are consistent with nearly stable global eustasy since 6000 bp thus challenging the assertion of significant additional melting of antarctica after the complete melting of the former northern hemisphere ice caps

mass failure of the north atlantic margin triggered by the cretaceous paleogene bolide impact the 65 ma chicxulub impact is known to have triggered large submarine slope failures near the crater in the gulf of mexico and caribbean here we show that the impact also precipitated massive submarine failure of the continental margin around the western north atlantic we have identified mass flow deposits containing impact ejecta of cretaceous paleogene boundary age in two deep sea cores more than 700 km from the continental margin the mass flows must have originated from the continental margin because they contain microfossils typical of shallow water environments and sedimentary features indicative of deposition by gravity currents geophysical data suggest that the mass wasting deposits may be present over the entire western north atlantic from puerto rico to the grand banks of canada and that much of the eastern margin of north america catastrophically failed during the cretaceous paleogene impact

a revised morpho and chronostratigraphy of the late and middle pleistocene coral reef terraces on southern barbados west indies the barbados coral reef terraces are one of the few type localities worldwide that provide insights into interglacial sea level change during the late and middle pleistocene several sea level estimates have been established since the late 1960s and each has contributed to the barbados model of sea level change this paper presents new morpho and chonostratigraphic data from the barbados coral reef terraces developed over the last 12 years the work is based on significant advances in electron spin resonance esr dating of fossil coral air photo interpretation and a greatly improved geomorphic map of preserved fossil beach formations and reef terraces above present sea level the need for a revision of past published morpho and chronostratigraphies is best demonstrated on the southern part of the island the morpho and chronostratigraphic sequence in this region is both more complex and diverse than has been assumed so far the revised morphostratigraphy presented here includes a differentiation of coral reef terraces wave cut platforms and other erosive features such as notches and cliffs our study of these geomorphic features combined with new numeric dating results esr u th enable a revised estimate of the spatial and temporal variation in tectonic uplift rate within south barbados these new rates are an essential requirement for more precise glacio eustatic sea level reconstructions during the late and middle pleistocene from this region

seismic stratigraphic correlation across the new england seamounts western north atlantic ocean correlation in the western north atlantic basin of deep water seismic stratigraphy across a basement high within the new england seamounts shows that the seismic sequence of the nova scotian rise is broadly similar to that off the united states time of seamount volcanism inferred from stratigraphic relations around the basement high is consistent with a hot spot origin but nearby stratigraphic data indicate that earlier and later eruptions occurred suggesting lithospheric weakness that predisposed this area to volcanism patterns of tertiary abyssal current erosion and sediment deposition were controlled by sea floor morphology around the seamounts and interaction of abyssal currents with the gulf stream

radiolarians decreased silicification as an evolutionary response to reduced cenozoic ocean silica availability it has been hypothesized that increased water column stratification has been an abiotic universal driver affecting average cell size in cenozoic marine plankton gradually decreasing cenozoic radiolarian shell weight by contrast suggests that competition for dissolved silica a shared nutrient resulted in biologic coevolution between radiolaria and marine diatoms which expanded dramatically in the cenozoic we present data on the 2 components of shell weight change size and silicification of cenozoic radiolarians in low latitudes increasing cenozoic export of silica to deep waters by diatoms and decreasing nutrient upwelling from increased water column stratification have created modern silica poor surface waters here radiolarian silicification decreases significantly r 0 91 p 0 001 from 0 18 shell volume fraction in the basal cenozoic to modern values of 0 06 a third of the total change occurred rapidly at 35 ma in correlation to major increases in water column stratification and abundance of diatoms in high southern latitudes southern ocean circulation present since the late eocene maintains significant surface water silica availability here radiolarian silicification decreased insignificantly r 0 58 p 0 1 from 0 13 at 35 ma to 0 11 today trends in shell size in both time series are statistically insignificant and are not correlated with each other we conclude that there is no universal driver changing cell size in cenozoic marine plankton furthermore biologic and physical factors have in concert by reducing silica availability in surface waters forced macroevolutionary changes in cenozoic low latitude radiolarians

a highly resolved record of relative sea level in the western mediterranean sea during the last interglacial period the magnitude and trajectory of sea level change during marine isotope stage mis 5e of the last interglacial period is uncertain in general sea level may have been 6 9 m above present sea level with one or more oscillations of up to several metres superimposed here we present a well dated relative sea level record from the island of mallorca in the western mediterranean sea for mis 5e based on the occurrence of phreatic overgrowths on speleothems forming near sea level we find that relative sea level in this region was within a range of 2 15 0 75 m above present levels between 126 600 400 and 116 000 800 years ago although centennial scale excursions cannot be excluded due to some gaps in the speleothem record we corrected our relative sea level record for glacio isostatic adjustment using nine different glacial isostatic models together these models suggest that ice equivalent sea level in mallorca peaked at the start of mis 5e then gradually decreased and stabilized by 122 000 years ago until the highstand termination 116 000 years ago our sea level record does not support the hypothesis of rapid sea level fluctuations within mis 5e instead we suggest that melting of the polar ice sheets occurred early in the interglacial period followed by gradual ice sheet growth a sea level record from mallorca shows no evidence of large millennial scale oscillations during the last interglacial

sea level changes and geoarchaeology between the bay of capo malfatano and piscinni bay sw sardinia in the last 4 kys abstract the bay of malfatano cape is the berthing home to one of the most important maritime structures from the punic roman times in the mediterranean two opposing monumental structures have been preserved between 7 and 2 m due to rising sea level recent studies have identified the paleo sea level relating the eustatic component to the glacio hydroisostatic deformations this paper through stratigraphic palaeontological and geochronological data aims to trace the bay of capo malfatano s evolution in relation to the sea level rise during the last 4 kys based on data derived from geophysical surveys paleoshore lines have been redrawn and compared with data derived from coring in the inner part of the creek finally we evaluated the relationship between changes in palaeogeography and human settlements from the bronze age the breakwaters have been surveyed in detail using d gps techniques correlated to the geodesic 0 level through this data the shape of the breakwaters has been reconsidered and consequently the palaeo sea level has been re evaluated

the evolutionary history of size variation of planktic foraminiferal assemblages in the cenozoic abstract the iterative evolutionary radiation of planktic foraminifers is a well documented macroevolutionary process here we document the accompanying size changes in entire planktic foraminiferal assemblages for the past 70 my and their relationship to paleoenvironmental changes after the size decrease at the cretaceous paleogene k p boundary high latitude assemblages remained consistently small size evolution in low latitudes can be divided into three major phases the first is characterized by dwarfs 65 42 ma the second shows moderate size fluctuations 42 14 ma and in the third phase planktic foraminifers have grown to the unprecedented sizes observed today our analyses of size variability with paleoproxy records indicate that periods of size increase coincided with phases of global cooling eocene and neogene these periods were characterized by enhanced latitudinal and vertical temperature gradients in the oceans and high diversity polytaxy in the paleocene and during the oligocene the observed minor size changes of the largely low diversity oligotaxic assemblages seem to correlate with productivity changes however polytaxy per se was not responsible for larger test sizes

global coccolith size variability in holocene deep sea sediments abstract we report on the size variability of coccoliths calcite platelets produced by planktic marine haptophyte algae in globally distributed holocene surface sediments the sizes of 400 600 coccoliths in 51 holocene deep sea carbonate ooze samples were measured using automated scanning electron microscopy and image analysis processes the resulting coccolith size histograms are highly variable but the largest 10 in each sample showed a size increase from the tropics to subpolar regions this is the opposite trend from the one observed in planktic foraminifera which have their largest tests in tropical regions in a subset of 13 samples which cover the major environmental gradients of today s surface waters coccolith sizes of the nine most common genera were analyzed these show that the observed macroecological size variability which is related to a complex mixture of environmental parameters is mostly the result of changing species occurrence and abundance biogeography rather than size changes within genera and species this holocene calibration will help to test evolutionary hypotheses of environmental selection in marine phytoplankton and can serve as a useful benchmark for analyses of coccolith size variability in older deep sea sediments

monteregian hotspot track a long lived mantle plume the monteregian hills the younger white mountains and the new england seamounts constitute a well defined hotspot track the evolution of the plume through time is obtained from the marine track the buoyancy flux of the plume when it made the new england seamounts was about 2 mg s 1 which would make it the seventh or eighth most active plume today the hotspot declined in activity after it made nashville seamount the buoyancy flux when it made corner seamounts and today is less than 0 5 mg s 1 the changes in the flux of the marine hotspot limit how far the marine flux can be extrapolated to the west onto the continental track and what can be learned in general about vulnerability of the continental lithosphere to hotspots the lack of an obvious track west of montreal may be due either to failure of the plume to penetrate the canadian shield to the lack of recognizable intrusions or to strengthening of the plume when it approached montreal

seismic stratigraphy of the shatsky rise sediment cap northwest pacific and implications for pelagic sedimentation atop submarine plateaus abstract pelagic sediments accumulated atop shatsky rise since early cretaceous time provide a valuable record of pacific paleoceanography the accepted sedimentation model invokes relatively continuous pelagic sediment accumulation punctuated by four regional hiatuses caused by changes in oceanic chemistry that framework was proposed more than two decades in the past and based on low quality single channel seismic profiles it was developed at the center of tamu massif the main topographic high of shatsky rise and extended to other highs with uncertainty owing to sparse data the availability of high quality seismic data and additional coring by the ocean drilling program and integrated ocean drilling program allows a re examination seismic and core data indicate that sedimentation atop shatsky rise has been complex with regional and local variability four major hiatuses were previously defined and tentatively correlated to nearby topographic highs these breaks occurred approximately during the aptian barremian and cenomanian coniacian ages of the cretaceous and during the paleocene and oligocene epochs of the cenozoic they are of variable length and tend to be of shorter duration at the summit of tamu massif but of longer durations elsewhere all produced erosional unconformities that may be related to mass wasting of the sediment cap edges each hiatus is approximately correlated with global falls of sea level suggesting a connection perhaps to intensified bottom currents at those times local variability is observed in the form of discontinuous layering non uniform sedimentation thinning of the sediment caps at their edges and local erosion near topographic highs these variations are likely the result of shifting bottom currents possibly resulting from interactions of internal tides with topography shatsky rise sedimentation is inherently punctuated and non uniform and the sedimentary record includes significant lateral variability other large oceanic plateaus are likely to exhibit similar sedimentary cap complexities

planktonic foraminifera as recorders of past surface water stratification the 18 o difference between shallow and deep living planktonic foraminifera is a proxy for the stratification of surface waters in holocene sediments from the atlantic this difference increases from about 0 in subpolar regions to 3 in the tropics the 18 o values of the shallow dwellers globigerinoides sacculifer and neogloboquadrina pachyderma mainly reflect surface water conditions the calcification depth of the deep living species globorotalia truncatulinoides right coiling is affected by the stratification of the water column in the subtropics shell formation of g truncatulinoides right coiling begins in weakly stratified surface waters in the tropics the initial shell is secreted below the mixed layer this hydrographically induced difference in calcification depth allows the use of the isotopic difference between g truncatulinoides and the shallow species as a proxy for the stratification of surface waters the 18 o between g truncatulinoides and g sacculifer from tropical gravity core geob 1523 1 was significantly lower during isotope stage 2 this suggests that the glacial temperature stratification of western equatorial atlantic surface waters was significantly reduced relative to the holocene

sea level change during the holocene in sardinia and in the northeastern adriatic central mediterranean sea from archaeological and geomorphological data abstract we provide new data on relative sea level change from the late holocene for two locations in the central mediterranean sardinia and ne adriatico they are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea level elevation twelve submerged archaeological sites were studied six aged between 2 5 and 1 6 ka bp located along the sardinia coast and a further six dated 2 0 ka bp located along the ne adriatic coast italy slovenia and croatia for sardinia we also use beach rock and core data that can be related to holocene sea level the elevations of selected significant archaeological markers were measured with respect to the present sea level applying corrections for tide and atmospheric pressure values at the time of surveys the interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea these data are compared with predictions derived from a new glacio hydro isostatic model associated with the last glacial cycle sardinia is tectonically relatively stable and we use the sea level data from this island to calibrate our models for eustatic and glacio hydro isostatic change the results are consistent with those from another tectonically stable site the versilia plain of italy the northeast adriatic italy slovenia and croatia is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions this indicates that the adriatic coast from the gulf of trieste to the southern end of istria has tectonically subsided by 1 5 m since roman times

u series evidence for two high last interglacial sea levels in southeastern tunisia abstract pleistocene raised marine deposits in southeastern tunisia consist of a siliciclastic unit that culminates at 3 m asl overlain by a carbonate rich unit with strombus bubonius that culminates at 5 m asl 234 u 238 u ratios on fossil ostraea shells from both units are compatible with a marine origin from the uranium incorporated into the shells and show narrowly clustered 230 th ages respectively between 147 and 110 ka and 141 and 100 ka the two units were therefore developed during marine isotopic substage 5e miss 5e last interglacial their heights are comparable to those of contemporaneous marine deposits found in many tectonically stable areas of the world such as in the bahamas and in bermuda and can therefore be used as indicators of eustatic changes during the last interglacial it is argued that on the basis of this evidence the last interglacial was characterised by two eustatic maxima

modern planktic foraminifers in the high latitude ocean abstract planktic foraminifers can be sensitive indicators of the changing environment including both the arctic ocean and southern ocean due to variability in their ecology biology test characteristics and fossil preservation in marine sediments they serve as valuable archives in paleoceanography and climate geochemistry over the geologic time scale foraminifers are sensitive to and can therefore provide proxy data on ambient water temperature salinity carbonate chemistry and trophic conditions through shifts in assemblage species composition and the shell chemistry of individual specimens production and dissolution of the calcareous shell as well as growth and remineralization of the cytoplasm affect the carbonate counter pump and to a lesser extent the soft tissue pump at varying regional and temporal scales diversity of planktic foraminifers in polar waters is low in comparison to lower latitudes and is limited to three native species neogloboquadrina pachyderma turborotalita quinqueloba and globigerina bulloides of which n pachyderma is best adapted to polar conditions in the surface ocean neogloboquadrina pachyderma hibernates in brine channels in the lower layers of the antarctic sea ice a strategy that is presently undescribed in the arctic in open antarctic and arctic surface waters t quinqueloba and g bulloides increase in abundance at lower polar to subpolar latitudes and globigerinita uvula turborotalita humilis globigerinita glutinata globorotalia inflata and globorotalia crassaformis complement the assemblages over the past two to three decades there has been a marked increase in the abundance of orcadia riedeli and g uvula in the subpolar and polar indian ocean as well as in the northern north atlantic this paper presents a review of the knowledge of polar and subpolar planktic foraminifers particular emphasis is placed on the response of foraminifers to modern warming and ocean acidification at high latitudes and the implications for data interpretation in paleoceanography and paleoclimate research

diversification patterns of planktic foraminifera in the fossil record abstract theories of taxonomic diversification dispute whether global diversity has an upper limit set by the strength of biological interactions or grows in unlimited fashion until catastrophic events reset the system we analyzed a global compendium of fossil planktic foraminifera from the early cretaceous to the present after correcting for temporal differences in sampling effort our results show that their morphological diversity has increased exponentially through time in two different phases the first phase collapsed at the cretaceous paleogene boundary transition the second phase developed through the cenozoic era and declined during the pliocene pleistocene interval a period of time that was dominated by enhanced climatic and oceanographic instability in none of these phases diversity reached an equilibrium level cenozoic faunas evolved faster than those inhabiting cretaceous oceans perhaps as a result of a higher environmental variability our results indicate that planktic foraminifera conform to an exponential diversification model however because catastrophic events have repeatedly reset the level of biological diversity and have kept it below the maximum we cannot confirm whether the level of diversity is potentially unlimited

quaternary marine terraces on sal island cape verde archipelago abstract the quaternary sedimentary record of sal island includes marine and related aeolian and alluvial fan deposits the substratum of the island is volcanic with ages between 25 and 0 6 ma quaternary marine units generally occur as raised marine terraces forming a broad staircase between elevations of 55 60 m and present sea level terraces include a basal conglomerate overlaid by calcarenite both host corals algae and molluscs a chronostratigraphic framework for the middle pleistocene to holocene units has been generated based on a geomorphologic map of the quaternary landforms and associated deposits and morphosedimentary analysis with support of laboratory dating u series by tims in corals 14 c analyses palaeomagnetic measurements and k ar ages from other literature u series dating of corals from marine terraces provides benchmarks for the last interglacial oxygen isotope substage 5e and holocene deposits the present elevation of the marine terraces and their staircase arrangement suggest a change in vertical movement trend around 330 ka from an uplift to either subsidence or stabilization

anomalous shifts in tropical pacific planktonic and benthic foraminiferal test size during the paleocene eocene thermal maximum paleocene eocene warming and changes in oceanic hydrography should have significantly impacted the ecology of marine microorganisms both at the surface and on the seafloor we analyzed several key characteristics of foraminifera from two shatsky rise odp leg 198 cores spanning the p e boundary including the maximum test diameters of the largest calcareous trochospiral benthic foraminifera and largest shallow dwelling planktonic foraminifera and the stable carbon and oxygen isotope ratios of benthic foraminifera and bulk samples we also qualitatively constrained changes in bottom water dissolved oxygen concentrations by quantifying changes in benthic species abundances we find warming synchronous with an unusual increase in the size of surface water planktonic in contrast to deep water benthic foraminifera which decrease in size we suggest that a decline in bottom water dissolved oxygen is the primary mechanism responsible for the size reduction of pacific deep sea benthic foraminifera whereas the contemporaneous size increase of surface water planktonic foraminifera is attributed to an increase in thermal stratification and decrease in local nutrient supply

widespread erosion and mass failure from the 51 ma montagnais marine bolide impact off southwestern nova scotia canada12 1this article is one of a series of papers published in this cjes special issue on the theme of mesozoic cenozoic geology of the scotian basin 2earth sciences sector contribution 20120241 the 51 ma montagnais impact crater on the outer scotian shelf is well known but the potential effects from the impact event on the slope and rise seaward of the crater have until now remained poorly understood through detailed seismic stratigraphic correlation and ties to available wells we define a threefold seismic stratigraphic subdivision for upper cretaceous to eocene strata on the shelf and slope calibrated to the most recent biostratigraphic results using this framework we identify a number of depositional and erosional products that are temporally consistent with a late ypresian impact event within the limits of seismic and biostratigraphic resolution we link a series of prominent failure scarps on the outer shelf and upper slope to a single widespread mass transport deposit mtd on the lower continental slope rise and abyssal plain failed material amassed in a large debris field referred to here as the montagnais mtd it covers an area of 93 000 km2 and travelled up to 580 km f

abiotic forcing of plankton evolution in the cenozoic we characterize the evolutionary radiation of planktic foraminifera by the test size distributions of entire assemblages in more than 500 cenozoic marine sediment samples including more than 1 million tests calibration of holocene size patterns with environmental parameters and comparisons with cenozoic paleoproxy data show a consistently positive correlation between test size and surface water stratification intensity we infer that the observed macroevolutionary increase in test size of planktic foraminifera through the cenozoic was an adaptive response to intensifying surface water stratification in low latitudes which was driven by polar cooling

interspecies variation in stable isotopic signals of maastrichtian planktonic foraminifera we measured stable isotopic signals of the largest specimens of all abundant species of planktonic foraminifera in late maastrichtian samples from three atlantic mid latitude and high latitude sites each sample is marked by a relatively small interspecies range of 18o values 1 2 to 0 8 each also exhibits an interspecies range of 13c values that resembles those of modern assemblages at similar latitudes 2 8 to 0 9 with greater ranges at lower latitudes these results indicate that late cretaceous planktonic foraminifera inhabited water masses characterized by a relatively narrow range of temperatures but may have occupied an array of niches as ecologically diverse as that of modern taxa maastrichtian taxa exhibit more complex relationships between skeletal morphology and vertical and seasonal paleohabitat affinities than previous paleoecologic models have assumed for example keeled taxa were not limited to cold or deep habitats and serial taxa appear to have occupied both warm near surface niches and the coolest or most saline habitats the isotopic differences between species indicate that apparent variation in maastrichtian stable isotopic signals strongly depends on the taxa analyzed narrowly constrained size fractions of rugoglobigerina species may provide a good estimate of relative variation in isotopic equilibria of near surface summer paleoconditions at low and middle latitudes gublerina species laeviheterohelix species and planoglobulina multicamerata appear the likeliest candidates for consistently tracking relative variation in isotopic equilibria of the coldest or most saline paleohabitats of maastrichtian planktonic foraminifera these isotopic results suggest that upper water column thermal gradients may have been only 3 to 5 c in mid latitude and high latitude regions they also suggest that the western and central atlantic mid latitude summer seasurface may have been much cooler or saltier in the maastrichtian than it is today finally they corroborate previous estimates of 10 c surface water at southern high latitudes

retracing the quaternary history of sea level changes in the spanish mediterranean atlantic coasts geomorphological and sedimentological approach abstract this study analyses coastal geomorphic responses to the various sea level changes that occurred throughout the quaternary period in the mediterranean and atlantic coasts of spain particular emphasis is paid to the geomorphic and stratigraphic record of the changes in amplitude duration and frequency associated with the major gradual climate changes observed in marine cores and ice oxygen isotope records during the early and middle pleistocene ca 2 6 myr ca 1 4 0 8 myr ca 0 4 0 2 myr and also with the rapid and abrupt late pleistocene and holocene climate changes with this aim the best preserved and most complete sedimentary sequences known in the spanish mediterranean and atlantic coasts covering diverse geodynamic and climatic contexts were selected and analyses this study is mainly based on field investigation of geomorphic sedimentologic and stratigraphic features of mapped morphosedimentary units combined with reliable chronological data the analyses include the interpretation of sedimentary environments the 3 d reconstruction of facies and morphosedimentary unit arrangement paying special attention to the lateral geomorphic relationships between marine and terrestrial morphosedimentary units developed during interglacials under sea level highstand scenarios the interglacials occurred during four key quaternary periods might be related with major gradual changes associated with glacial climate cycles reported from marine and ice oxygen isotope records almost coeval changes in geomorphological styles are reported from all studied areas regardless of their specific geodynamic context results from the mediterranean realm suggest that this area is more sensitive to climatic and sea level variability than the spanish atlantic coast particularly in the case of rapid and abrupt changes

coastal uplift in continental collision plate boundaries data from the last interglacial marine terraces of the gibraltar strait area south spain abstract the spatial height analyses of deposits belonging to isotopic substages 5e and 5c indicate the occurrence of differential uplift in the gibraltar strait area maximum mean uplift rates do not reach values of 0 2 mm year displaying a gentle deceleration from 0 15 to 0 10 mm year for the last 128 ka maximum estimated rates are recorded in the central sector of the gibraltar strait the combined analysis of the accumulated vertical movements before and after iss 5c indicates that differential uplift is accommodated along ne sw sinistral and nw se dextral mostly inherited strike slip fault systems separating coastal segments of contrasting uplifting subsiding behaviour the occurrence of inversions in the relative vertical offsets along some of these faults arises when this combined analysis is performed a model of asymmetric pure shear defined by these two fault systems generated in response to the roughly n s convergence between the african and eurasian plates can explain the recorded uplift patterns in this transpressive setting generated by the africa eurasia continental collision the recent convergence 4 mm year is mostly released by shear processes and subsidiary e w horizontal extension whilst the recorded coastal uplift only represents a low percentage of the recent convergence rates

geomorphology stratigraphy and facies analysis of some late pleistocene and holocene key deposits along the coast of sardinia italy abstract two major synthems have been recognised along the coasts of sardinia the older one is composed of two sub synthems the oldest of which was formed in high energy boulder beaches and is a thin condensed transgressive sequence usually located at the foot of a marine cliff the overlying sub synthem was generated by aeolian slope interdunal ponds and alluvial depositional environments it is widespread and terraces and relict dune fields are usually deeply dissected its deposition is associated with a cold and arid climate the aeolian and alluvial deposition was interrupted by the evolution of steppe prairie soils a more evolved reddish brown bt paleosol is locally found at the top of the sequence the younger synthem is made of beach and coastal lagoon and swamps it is more variable in thickness rests unconformably over the older one and has no sedimentary cover it is laterally correlated to the present day depositional environments such as alluvial plains and beaches unfortunately because beach deposits of this synthem are found up to 6 m asl and a marine notch is present at 5 6 m capo san marco the widespread idea that sardinia is a stable area and that marine sea level during the holocene was never higher than nowadays led to their previous attribution to mis 5e however all the stratigraphic geomorphic and pedological evidence indicates that only the older sub synthem can be correlated with the mis 5e high stand the younger sub synthems made of aeolian lacustrine and alluvial deposits at cala gonone santa reparata capo s marco and s giovanni di sinis were deposited during the rest of the late pleistocene the younger synthem evolved during the holocene and this is the chronological setting of the beach deposits at is arenas scala e croccas santa reparata and capo san marco radiocarbon dating confirms these attributions unfortunately osl dating suggests an older chronology for these deposits and therefore it seems that further investigations are needed

planktic foraminiferal dissolution in the twilight zone abstract calcite dissolution of planktic foraminifers that settle from the surface ocean to depths has been assessed using the weight size relationship of tests and correlated to carbonate ion concentration co 3 2 of ambient sea water globigerina bulloides and globigerinita glutinata were sampled from the north atlantic and the arabian sea during different seasons spring and fall and the monsoons respectively test weight has been determined for single tests from narrow size classes 250 8 m and 300 7 m minimum test diameter initial test weight of both species in surface waters differs between regions and seasons weight loss of settling tests in the twilight zone between 100 and 1000 m water depths averaged 19 below the twilight zone 1000 2500 m no weight loss occurs on average and tests may even gain weight remineralization of settling planktic foraminiferal tests is most pronounced at maximum co 3 2 accordingly strong dissolution occurs in the twilight zone at the depth of maximum decrease in co 3 2 it is assumed that dissolution of planktic foraminiferal calcite is caused by co 3 2 under saturation inside the test buffered by diffusive exchange of co 3 2 ions with the ambient sea water through the pores and aperture consequently reconstruction of small scale differences in seawater co 3 2 from test weight alone is not feasible and systematic correlation between test weight and co 3 2 of the ambient sea water is statistically not significant at constant co 3 2 remineralization cannot be deduced from test weight neither at high nor low co 3 2 saturation in total our data suggest that the global vertical planktic foraminiferal caco 3 flux is about 19 lower than calculated by schiebel 2002 planktic foraminiferal sedimentation and the marine calcite budget global biogeochemical cycles 16 4 1065 doi 10 1029 2001gb001459

history of seawater carbonate chemistry atmospheric co 2 and ocean acidification humans are continuing to add vast amounts of carbon dioxide co2 to the atmosphere through fossil fuel burning and other activities a large fraction of the co2 is taken up by the oceans in a process that lowers ocean ph and carbonate mineral saturation state this effect has potentially serious consequences for marine life which are however difficult to predict one approach to address the issue is to study the geologic record which may provide clues about what the future holds for ocean chemistry and marine organisms this article reviews basic controls on ocean carbonate chemistry on different timescales and examines past ocean chemistry changes and ocean acidification events during various geologic eras the results allow evaluation of the current anthropogenic perturbation in the context of earth s history it appears that the ocean acidification event that humans are expected to cause is unprecedented in the geologic past for which sufficiently well preserved records are available

a pronounced dry event recorded around 4 2 ka in brine sediments from the northern red sea partly laminated sediments were sampled from the brine filled anoxic shaban deep basin in the northern red sea at about 4200 cal yr bp more than two millennia of anoxic sedimentation is replaced by a sub oxic facies strongly suggesting the episodic absence of the brine at the same time stable oxygen isotopes from surface dwelling foraminifera show a sharp increase within less than 100 yr pointing to a strong positive salinity anomaly at the sea surface this major evaporation event significantly enhanced the renewal of deep water and the subsequent ventilation of the small shaban deep basin the timing and strength of the reconstructed environmental changes around 4200 cal yr bp suggest that this event is the regional expression of a major drought event which is widely observed in the neighboring regions and which strongly affected middle east agricultural civilizations

sequence of events from the onset to the demise of the last interglacial evaluating strengths and limitations of chronologies used in climatic archives the last interglacial lig represents an invaluable case study to investigate the response of components of the earth system to global warming however the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies this feature sets limitations to the accuracy of the stratigraphic assignment of the climatic sequence of events across the globe during the lig here we review the strengths and limitations of the methods that are commonly used to date or develop chronologies in various climatic archives for the time span 140 100 ka encompassing the penultimate deglaciation the lig and the glacial inception climatic hypotheses underlying record alignment strategies and the interpretation of tracers are explicitly described quantitative estimates of the associated absolute and relative age uncertainties are provided recommendations are subsequently formulated on how best to define absolute and relative chronologies future climato stratigraphic alignments should provide 1 a clear statement of climate hypotheses involved 2 a detailed understanding of environmental parameters controlling selected tracers and 3 a careful evaluation of the synchronicity of aligned paleoclimatic records we underscore the need to 1 systematically report quantitative estimates of relative and absolute age uncertainties 2 assess the coherence of chronologies when comparing different records and 3 integrate these uncertainties in paleoclimatic interpretations and comparisons with climate simulations finally we provide a sequence of major climatic events with associated age uncertainties for the period 140 105 ka which should serve as a new benchmark to disentangle mechanisms of the earth system s response to orbital forcing and evaluate transient climate simulations

palaeoenvironmental vs evolutionary control on size variation of coccoliths across the lower middle jurassic size is an easily quantifiable trait probing the respective influence of evolution and palaeoenvironment on organisms through time after the stressed period that spanned across western tethys epicontinental seas during the early toarcian the following rebuilding of a restored water column ecosystem is coeval with the size increase of the lotharingius genus coccoliths one of the main pelagic producers at that time in order to quantitatively assess the coccolith size evolution during a time span of 10 myr measurements of seven morphospecies of lotharingius across the toarcian and early aalenian were performed this study was carried out on a total of 5500 specimens from samples retrieved from two distinctive palaeoenvironmental settings in the western mediterranean tethys three sections from the lusitanian basin in portugal and one section from the causses basin in southern france for each specimen coccolith length width and central area length and width were measured using specific measurement software statistical and data analysis tools were used in order to evaluate significant resemblances and or differences between different size groups and samples two main clusters are acknowledged from this study small sized lotharingius is 4 m in addition to common evolutionary processes changes in palaeoenvironmental conditions were taken into account to explain such a size distribution although background evolution pushed the lotharingius genus toward larger sizes palaeoenvironmental conditions seemed to play an important role in the toarcian early aalenian morphological evolution of this taxon the production of larger coccoliths profited from stable environmental conditions whereas smaller morphotypes dominated during periods marked by stress the transition from small to large lotharingius was synchronous in the two investigated western tethys basins at the bifrons gradata or variabilis ammonite zone boundary middle toarcian thus representing an important event for the lower jurassic calcareous nannofossil biostratigraphy

maastrichtian foraminiferal and paleoceanographic changes on milankovitch timescales milankovitch scale alternations in maastrichtian hemipelagic strata from ocean drilling program hole 1050c blake nose provide a natural experiment of paleoceanography and foraminiferal paleoecology in a tropical subtropical greenhouse ocean cycles are 30 50 cm thick and thought to reflect the 21 kyr precessional cycle high planktic 18o values are correlated with high planktic but low benthic 13c values indicating that cooler and or more saline surface waters were associated with higher productivity high productivity intervals are also characterized by high ca concentrations enrichment in feldspar and kaolinite and high relative abundance of heterohelix spp globigerinelloides spp and laeviheterohelix glabrans conversely low productivity intervals have low planktic 18o values high fe and ti concentrations enrichment in quartz illite and chlorite and relative increases in globotruncana spp and pseudoguembelina spp potential forcing mechanisms for observed covariation include cyclic variation in water column stratification variation in continental nutrient fluxes and changes in the intensity of upwelling

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

late neogene planktonic foraminifera of the cibao valley northern dominican republic biostratigraphy and paleoceanography abstract an assemblage of planktonic foraminifera is described from 125 samples taken from the cercado gurabo and mao formations in the cibao valley northern dominican republic the primary objectives of this study are to establish a biochronologic model for the late neogene of the dominican republic and to examine sea surface conditions within the cibao basin during this interval the cercado formation is loosely confined to zones n17 and n18 7 0 5 9 ma the gurabo formation spans zones n18 and n19 5 9 4 5 ma the mao formation is placed in zone n19 4 5 3 6 ma changes in the relative abundances of indicator species are used to reconstruct sea surface conditions within the basin increasing relative abundances of globigerinoides sacculifer and globigerinoides ruber in conjunction with a decreasing relative abundance of globigerina bulloides suggests the onset of increasing sea surface temperature and salinity in conjunction with diminishing primary productivity at 6 0 ma abrupt increases in the relative abundances of g sacculifer and g ruber at 4 8 ma suggest a major increase in sea surface temperature and salinity in the early pliocene the most likely mechanism for these changes is isolation of the caribbean ocean through progressive restriction of pacific caribbean transfer via the central american seaway periods of high productivity associated with upwelling events are recorded in the upper cercado formation 6 1 ma and in the middle mao formation 4 2 ma by spikes in g bulloides and neogloboquadrina spp respectively the timing of major increases in sea surface salinity and temperature as well as decreasing productivity 4 8 ma and periods of upwelling 6 1and 4 2 ma in the cibao basin generally corroborate previously suggested caribbean oceanographic changes related to the uplift of panama changes in sea surface conditions depicted by paleobiogeographic distributions in the cibao basin suggest that shoaling along the isthmus of panama had implications in a shallow caribbean basin as early as 6 0 ma major paleobiologic changes between 4 8 and 4 2 ma likely represent the period of final closure of the cas and a nearly complete disconnection between pacific and caribbean water masses this study illustrates the use of planktonic foraminifera in establishing some paleoceanographic conditions salinity temperature productivity and upwelling within a shallow water basin outlining the connection between regional and localized oceanographic changes

palaeo shorelines of the historic period sant antioco island south western sardinia italy abstract this article illustrates the results of the recent multidisciplinary studies carried out in the southern part of sardinia western mediterranean sea on the last 2 5 ka palaeo sea level the survey has specifically investigated some geo archaeological sea level markers related to two submerged structures the first represents a near port building of punic roman age 2300 100 bp and is located in the sant antioco lagoon the second structure is a road of roman age 1030 20 bp in the near coastal area of palmas gulf a bone and ceramics fragment rich pericoastal beach rock chronologically referable to the imperial roman age between tiberius and claudius 1940 20 bp has been studied the results of this study fit the new predicted glacio hydro isostatic model of lambeck et al and agree with similar data from other sardinian sites that show almost no vertical tectonic mobility during the late holocene the study of a new stratigraphic section along the western coast of sant antioco island has identified the inner margin of a wave cut platform with fossils referred to mis 5 5 at 7 5 m highlighting a relative tectonic stability since the upper pleistocene for this area the geomorphological context of palmas gulf continental shelf shows a buried palaeo riverbed referred to mis 2 and a coastal palaeo system related to the holocene sea level change between 15 and 25 m these features are typical of the conservative style of low tectonic mobility areas

global sea level fluctuations during the last interglaciation mis 5e the geomorphology and morphostratigraphy of numerous worldwide sites reveal the relative movements of sea level during the peak of the last interglaciation marine isotope stage mis 5e assumed average duration between 13072 and 11972 ka because sea level was higher than present deposits are emergent exposed and widespread on many stable coastlines correlation with mis 5e is facilitated by similar morphostratigraphic relationships a low degree of diagenesis uranium thorium u th ages and a global set of amino acid racemization aar data this study integrates information from a large number of sites from tectonically stable areas including bermuda bahamas and western australia and some that have experienced minor uplift 2 5 m 100 ka including selected sites from the mediterranean and hawaii significant fluctuations during the highstand are evident at many mis 5e sites revealed from morphological stratigraphic and sedimentological evidence rounded and flat topped curves derived only from reef tracts are incomplete and not representative of the entire interglacial story despite predictions of much different sea level histories in bermuda the bahamas and western australia due to glacio and hydro isostatic effects the rocks from these sites reveal a nearly identical record during the last interglaciation the last interglacial highstand is characterized by several defined sea level intervals slis that include sli 1 post glacial mis 6 5e termination ii rise to above present before 130 ka sli 2 stability at 2 to 3 m for the initial several thousand years 130 to 125 ka during which fringing reefs were established and terrace morphology was imprinted along the coastlines sli 3 a brief fall to near or below present around 125 ka sli 4 a secondary rise to and through 3 4 m 124 to 122 ka followed by sli 5 a brief period of instability 120 ka characterized by a rapid rise to between 6 to 9 m during which multiple notches and benches were developed and sli 6 an apparently rapid descent of sea level into mis 5d after 119 ka u th ages are used to confirm the last interglacial age of the deposits but unfortunately in only two cases was it possible to corroborate the highstand subdivisions using radiometric ages sea levels above or at present were relatively stable during much of early mis 5e and the last 6 7 ka of mis 1 encouraging a comparison between them the geological evidence suggests that significant oceanographic and climatic changes occurred thereafter midway through and continuing through the end of mis 5e fluctuating sea levels and a catastrophic termination of mis 5e are linked to the instability of grounded and marine based ice sheets with the greenland gis and west antarctic wais ice sheets being the most likely contributors late mis 5e ice volume changes were accompanied by oceanographic reorganization and global ecological shifts and provide one ominous scenario for a greenhouse world r 2007 elsevier ltd all rights reserved