87sr86sr in late proterozoic carbonates evidence for a mantle event at 900 ma ago abstract strontium isotopic measurements were made on late proterozoic carbonates from west african craton comparison of samples with acceptable trace element patterns with coeval data from southern africa and with the published australian results suggests that the 87 sr 86 sr ratio of the late proterozoic sea water evolved in the following manner about 0 7075 at 1000 50 ma 0 7056 to 0 7074 at 900 50 ma 0 7068 to 0 7091 0 7106 at 800 50 ma 0 7074 to 0 7077 at 700 50 ma and 0 7076 to 0 7089 0 7096 at 600 50 ma ago the variations are comparable in magnitude and frequency to those described previously for the phanerozoic strontium isotopic values in the radiogenic part of this range suggest that the continental river flux of sr into late proterozoic oceans was of comparable isotopic composition to its present day counterpart 0 711 consequently the non radiogenic 87 sr 86 sr value at 900 50 ma ago signifies a large flux of mantle strontium into the ocean at this time because the present time resolution is only about 75 25ma additional sampling as well as better stratigraphie resolution and more definite selection criteria are required for construction of a more detailed late proterozoic sea water curve

geophysical evidence for the east antarctic plate boundary in the weddell sea an improved gondwanaland reconstruction compatible with geological and geophysical information from the surrounding oceans and continents seems to require microplates to solve the enigmatic pre early mesozoic tectonic relation between west and east antarctica1 new multi channel seismic reflection data from the southeastern weddell sea acquired during the 1984 85 norwegian antarctic research expedition nare have outlined a linear wsw ene trending basement ridge buried below the continental slope over a distance of 700 km this structural high truncates the trend of the large sedimentary basins below the filchner and ronne ice shelves and may continue to within a few hundred kilometres of the antarctic penninsula we interpret the basement ridge as part of the east antarctic plate boundary during the break up of gondwana the morphology and structure of this boundary show greater apparent similarity to a rifted or obliquely rifted margin than to the sheared margin which is predicted by current reconstructions2 3 a linear east antarctic plate margin extending to the vicinity of the antarctic peninsula makes any post rift micro plate motion in the weddell embayment unlikely

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

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

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

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

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

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

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

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

burrow mediated carbonate dissolution in rudist biostromes aurisina italy implications for taphonomy in tropical shallow subtidal carbonate environments abstract in upper cretaceous rudist biostromes at aurisina italy marked taphonomic loss of radiolitids by burrow mediated dissolution and mechanical disintegration illustrates the relation between synecology and early diagenesis in the fossilization of tropical shallow water bioconstructions the studied platform succession accumulated in a prevalently open lagoon with bioturbated carbonate sand rudist thickets bioclastic dunes and areas with shelly lime ooze rudist biostromes consist of radiolitids and hippuritids or of radiolitids only and have an open parautochthonous rudist fabric with a matrix of bioclastic bioturbated wackestone swirly disorientation of bioclasts records early softground bioturbation later firmground burrows comprise an irregular network of tunnels and chambers filled with bioclastic packstone to grainstone the size geometry and sediment fill of the firmground burrows suggest that they were produced by crustaceans radiolitid preservation ranges from complete to relictic radiolitid relicts formed by a spalling and or dissolution of the cellular boxwork ostracum of the attached valve leaving calcite tubes built by a distinct thin ostracal shell layer or b dissolution of the entire shell leaving the sedimentary fills of the intertabular spaces of the attached valve as a diagnostic vestige or c shell dissolution within the firm sediment with subsequent filling of the biomould by bioclastic wackestone to packstone to grainstone loss of radiolitids produced a taphonomic bias towards rudists with non cellular ostracum locally taphonomic loss produced ghost biostromes composed nearly entirely of faint radiolitid relicts shell dissolution resulted from chemical gradients in the sediment within and near the burrows and from enhanced microboring and microbial infestation dissolution of radiolitids was favoured by the combined effects of chemical instability of hypostracal aragonite and by the structure of the calcitic boxwork ostracum of thin walled cells some biostromes are intercalated with or are capped or overlain within a short vertical distance by a hardly recognizable emersion surface as a consequence of the shallow depth of biostrome accumulation taphonomic loss by dissolution is widespread in open parautochthonous rudist fabrics and confirms actuogeological results of other authors that bioturbation mediates carbonate dissolution also under shallow tropical waters supersaturated for calcium carbonate the amount of carbonate dissolved upon burrowing of the biostrome matrix is hardly quantifiable but by analogy to recent carbonate environments may have been large within bioconstructions deep tiered burrowing occurred at least since the carboniferous taphonomic loss by dissolution thus may have been active in the fossilization of tropical shallow water mounds and biostromes over much of phanerozoic times

the sedimentary structure in the western weddell sea abstract the western weddell sea was one of the regions where breakup of gondwana was initiated about 180 ma the perennial ice coverage makes it difficult to obtain knowledge about the thickness and structure of the sediments that might reveal information about the break up process and the evolution of the weddell sea basin seismic investigations south of 66 s provide a first detailed view of the sediment structure of the westernmost weddell sea in addition four wide angle seismic measurements with offsets up to 31 km were undertaken the sediment thickness ranges from 4 8 0 3 to 7 3 0 3 km but seems to be relatively uniform in the area between the eastern continental margin of the antarctic peninsula at 52 w and 35 w three out of four measurements of the sediment thickness in this area are between 4 8 and 5 7 km the depth of the acoustic basement is constrained by both the wide angle data and by seismic reflection profiles acquired at the same time a comparison of the two western wide angle seismic measurements with estimates for the non magnetic overburden derived from aeromagnetic data show a deviation of more than 1 km the depth velocity functions reveal that the sediments of the western weddell sea are divided into two sequences that are separated by a broad transition zone at a depth of 6 7 km

geochemical indicators of depositional and early diagenetic facies in holocene carbonate muds and their preservation potential during stabilisation holocene carbonate muds 63 m fraction and macro organic matter were collected from marine subtidal mudbanks and supralittoral mud islands of florida bay and freshwater marshes of the florida everglades u s a geochemistry sedimentology and mineralogy were used to determine whether carbonate mud formation in specific marine and freshwater environments was geochemically distinct and to assess the importance of early diagenetic reactions on mud chemistry and mineralogy significant variations were found in the relative amounts of carbonate minerals not just between the marine and freshwater environments but also within florida bay in particular mg calcite is enriched in crane key muds by 10 relative to nearby cross bank the mg calcite appears to precipitate in the surface living cyanobacterial mats of the key and seems to be linked to mg chelation by the cyanobacterial organic matter this mg calcite has a distinct 13c around 4 6 lighter than mg calcite derived from thalassia epibionts in the cross bank muds dolomite was found just below the cyanobacterial mats forming in the only part of the core where reactive organic carbon has been completely removed by sulphate reducing bacteria the 13c values of this dolomite at least 4 are consistent with previously published 13c values of dissolved inorganic carbon in pore waters at this horizon which support dolomite formation in situ mg supply for dolomite formation may be from dissolution of the overlying cyanobacterial mat mg calcite the various types of organic matter have distinctive 13c values ranging from 25 mangrove and sawgrass to 10 cyanobacterial mats and 8 thalassia seagrass values intermediate between these end members record mixing of the organic matter types which shows particularly the time when the bank muds became dominated by thalassia organic matter i e were relatively removed from mangrove vegetation five holocene mud suites bank key cyanobacterial mats mangrove swamp and freshwater everglades swamp show distinct chemical signatures in their mean 13c 18o mgco3 and sr values na distinguishes between seawater and non seawater influenced environments but fe mn and p are mainly controlled by non carbonate materials comparison with published stable isotope and elemental data for pleistocene limestones in the south florida area suggests that only the facies diagnostic signatures of 13c and mg will be resolvable once the muds have been stabilised to micrite alteration of the 18o and sr values during stabilisation will probably be more severe to the extent that original facies variations are destroyed

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

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

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

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

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

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

airborne gravity measurement over sea ice the western weddell sea an airborne gravity study of the western weddel sea east of the antarctic peninsula has shown that floating pack ice provides a useful radar altimetric reference surface for altitude and vertical acceleration corrections surface for alititude and vertical acceleration corrections to airborne gravimetry airborne gravimetry provides an important alternative to satellite altimetry for the sea ice covered regions of the world since satellite alimeters are not designed or intended to provide accurate geoidal heights in areas where significant sea ice is present within the radar footprint errors in radar corrected airborne gravimetry are primarily sensitive to the variations in the second derivative of the sea ice reference surface in the frequency pass band of interest with the exception of imbedded icebergs the second derivative of the pack ice surface closely approximates that of the mean sea level surface at wavelengths 10 20 km with the airborne method the percentage of ice coverage the mixture of first and multi year ice and the existence of leads and pressure ridges prove to be unimportant in determining gravity anomalies at scales of geophysical and geodetic interest provided that the ice is floating and not grounded in the weddell study an analysis of 85 crosstrack miss ties distributed over 25 data tracks yieldsmore an rms error of 2 2 mgals significant structural anomalies including the continental shelf and offsets and lineations interpreted as fracture zones recording the early spreading directions within the weddell sea are observed in the gravity map less

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

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

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

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

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

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

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

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

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

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

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

bathymetry depth to magnetic basement and sediment thickness estimates from aerogeophysical data over the western weddell basin we estimated the bathymetry and sediment thickness of a remote and difficult to access portion of the antarctic continental margin using aerogeophysical surveying techniques the u s argentina chile aerogeophysical survey collected magnetic and gravity data over the basins surrounding the antarctic peninsula thirty seven of these flight lines were used to estimate bathymetry and depth to magnetic basement for the western weddell basin a wavenumber technique was applied to individual magnetic anomaly profiles in an automated fashion to obtain estimates of the depth to magnetic basement the bathymetric estimates were obtained by admittance inversions of the gravity field the results were then gridded at a 40 km interval for the region 64 w 44 w 73 s and 62 s bathymetric estimates and depth to magnetic basement estimates were differenced at each grid point to obtain a regional estimate of the thickness of nonmagnetic overburden assumed to be sediment subsequent spot measurements of topography in the estimated region of the continental margin generally agree to about 52 m the estimated magnetic basement deepens from the antarctic peninsula margin eastward to a maximum of 10 12 km near 54 w we also postulate the existence of two moderately large basins flanking the eastward continuation of the jason peninsula farther east the basement steps upward with a correspondent thinning of the sedimentary layer along the east coast of the peninsula results agree well with seismic studies on james ross island and magnetotelluric studies on marambio island and the larsen nunatak as well as the british antarctic survey basement estimates from aeromagnetic data this study further demonstrates the utility of combined application of airborne and satellite geophysical techniques in the study of structure and tectonic evolution of continental margins and marine basins

the age of the weddell basin the deep oceanic basin occupied by the weddell sea separates the east antarctic craton from the antarctic peninsula a largely post palaeozoic orogenic belt an understanding of the tectonic evolution of the basin would resolve most of the remaining problems of gondwanaland reconstruction which revolve around the relative positions of these two fragments and south america norton and sclater1 conclude that indian ocean marine geophysical data essentially support the smith and hallam fit2 but the unacceptable overlap ofundoubtedly old continental crust3 5 on the antarctic peninsula and falkland plateau implies relative motion between the peninsula and east antarctica such motion is not required by the reconstruction of barron and others7 8 which however can be criticized on other grounds9 10 the marine geophysical observations within the intervening ocean basins have proved useful in formulating plate tectonic reconstructions fracture zone trends seafloor spreading type magnetic anomalies crustal heat flux and crustal depth all provide clues to the timing and direction of the continental motions the acquisition of geophysical data from the weddell sea region has been slow11 13 however the combined interpretation of the two largest data sets extant12 13 now being undertaken seems likely to provide a more tightly constrained gondwanaland solution as a first step we report here an estimated age for the weddell sea floor in the area bounded by 60 and 73 s 5 and 35 w shown in fig 1

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

geodynamic evolution of the antarctic peninsula during mesozoic times and its bearing on weddell sea history this review of the tectonic evolution of the antarctic peninsula during mesozoic times highlights four main events 1 late triassic late jurassic extension 2 late jurassic early cretaceous dextral transpression 3 early cretaceous extension and 4 mid cretaceous compression magmatism was virtually continuous during much of this period with the exception of possible breaks in the known record in early jurassic and late jurassic early cretaceous times the second of these breaks corresponded to the first compressional event there was no apparent hiatus in the magmatic record during the mid cretaceous compressional event although there was a significant change in the pattern of sedimentation in the larsen basin on the eastern margin of the weddell sea at about that time the tectonic evolution of the peninsula is compared to and puts some constraints on existing weddell sea models the late triassic late jurassic arc extension correlates with initial rifting in the weddell sea region during sinistral motion between east and west gondwana however there is no known record of large scale pre mid jurassic transcurrent deformation in the antarctic peninsula that would have been consistent with rotation of west antarctic crustal blocks in the initial rifting period the peninsula wide late jurassic early cretaceous compressional event may correlate with the major change in gondwana plate motions from e w to n s african reference frame separation of east and west gondwana this change probably resulted in formation of an ocean continent boundary along the northern margin of the weddell sea embayment and initial seafloor spreading geological data do not seem to support subduction of southwestern proto weddell sea oceanic lithosphere beneath the eastern margin of the peninsula at that time cretaceous arc extension was coeval with the initial seafloor spreading phase in the weddell sea mid cretaceous arc compression linked to a global increase in ocean floor spreading rates and a superplume event correlates with a change from ne sw to nw se spreading in the weddell sea

aeromagnetic data from the southern weddell sea embayment and adjacent areas synthesis and interpretation a new regional aeromagnetic anomaly map covering the southern weddell sea and surrounding areas was produced by combining russian and british magnetic anomaly data acquired between 1973 and 1989 the map is divided into four zones on the basis of characteristic anomaly wavelength antarctic peninsula weddell sea embayment haag nunataks and the western coast of east antarctica over the southern weddell sea and the ronne and filchner ice shelves the magnetic field is relatively smooth indicating a thick sedimentary cover although there are some distinctive anomalies a broad positive anomaly is clearly visible running w e across the north of the area which is interpreted as representing the continent ocean boundary the most prominent magnetic feature is the elongate explora anomaly which runs parallel to the coast of east antarctica and continues over berkner island terminating at the dufek massif we interpret the source of this anomaly as rift related volcanic rocks probably emplaced around the same time as the dufek intrusion the rift itself is interpreted as running south between the andenes escarpment and east antarctica and terminating south of berkner island russian gravity profiles show that berkner island does not have an associated bouguer anomaly although a large positive anomaly approx 80 mgal is seen to the east of the island over the filchner ice shelf suggesting the presence of a second rift structure gravity modelling across these features shows thinned crust below the ronne and filchner ice shelves indicating that the whole area has undergone significant extension a gravity model across the flanks of berkner island is used to estimate the ratio of unstretched to stretched crustal thickness the resulting value of approximately 2 7 indicates that enough extension has taken place to induce melting supporting the idea that the source of the magnetic anomaly over berkner island is rift related volcanic rocks

microseismicity of the ultraslow spreading gakkel ridge arctic ocean a pilot study summary the active mid ocean ridge of the arctic ocean named gakkel ridge is the slowest spreading ridge of the global system of mid oceanic ridges with full spreading rates declining from about 12 5 to 6 mm yr 1 from west to east geological models of seafloor spreading predict a decreasing intensity of magmatic processes with decreasing spreading rate in summer 2001 the multidisciplinary arctic mid ocean ridge expedition amore2001 discovered robust magmatism at western gakkel ridge an amagmatic section further east and pronounced volcanic centres at eastern gakkel ridge during amore2001 an attempt was made at recording the microearthquake activity of the ridge which allows important insights into the character and dynamics of active crustal accretion at the ridge axis due to the permanent ice cover of the arctic ocean the use of ocean bottom seismometers bears the risk of instrument and data loss in this pilot study we used for the first time drifting ice floes as platforms for small seismological arrays the arrays consisted of four three component seismometers equipped with gps devices and arranged as a triangle with a central seismometer and a side length of about 1 km three such arrays were deployed in different rift segments and recorded the seismic activity continuously for 5 11 days at a sampling rate of 100 hz the array technique allowed to distinguish clearly between icequakes and earthquakes and to localize the earthquake source to within few kilometres or less depending on epicentral distance we intensively discuss the detection capabilities and the location accuracy of this single array on a drifting ice floe earthquake magnitudes could not be calculated in our pilot study but are estimated to be significantly smaller than magnitude 2 by comparison with a regional earthquake of known magnitude furthermore we analyse the characteristics of the recorded seismic events ranging from long waveforms of regional events to short local events with reverberations in the water column all of the arrays recorded numerous microearthquakes in the central rift valley and on its flanks which we interpret as tectonic earthquakes a swarm of microearthquakes was localized with high accuracy underneath the crest of a volcanic ridge in the rift valley and is proposed to have magmatic origin the pilot study was thus successful in detecting localizing and interpreting microearthquakes below magnitude 2 at gakkel ridge however we suggest improvements of the method for a comprehensive microearthquake survey of gakkel ridge which should aim at an understanding of active magmatism and faulting at ultraslow spreading ridges

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

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

antarctic topography at the eocene oligocene boundary we present a reconstruction of the antarctic topography at the eocene oligocene ca 34 ma climate transition this provides a realistic key boundary condition for modeling the first big antarctic ice sheets at this time instead of using the present day bedrock topography which has changed significantly from millions of years of tectonism and erosion we reconstruct topography using a set of tools including ice sheet erosion models models of thermal subsidence and plate movement erosion estimates are constrained with offshore sediment volumes estimated from seismic stratigraphy maximum and minimum topographic reconstructions are presented as indicators of the range of uncertainty our results point to a significant upland area in the ross sea marie byrd land and weddell sea sectors in addition east antarctic coastal troughs are much shallower than today due to the restoration of material that has been selectively eroded by the evolving ice sheets parts of east antarctica have not changed since the e o boundary because they were protected under non erosive cold based ice the reconstructions provide a better defined boundary condition for modeling that seeks to understand interaction between the antarctic ice sheet and climate along with more robust estimates of past ice volumes under a range of orbital settings and greenhouse gas concentrations

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

deep sea pre glacial to glacial sedimentation in the weddell sea and southern scotia sea from a cross basin seismic transect abstract identification of the pre glacial transitional and full glacial components in the deep sea sedimentary record is necessary to understand the ice sheet development of antarctica and to build circum antarctic sediment thickness grids for palaeotopography bathymetry reconstructions which constrain palaeoclimate models a 3300 km long weddell sea to scotia sea multichannel seismic reflection data transect was constructed to define the first basin wide seismostratigraphy and to identify the pre glacial to glacial components seven main seismic units were mapped of these ws s1 ws s2 and ws s3 comprise the inferred cretaceous palaeocene pre glacial regime 27 ma in our age model ws s4 the eocene oligocene transitional regime 27 11 ma and ws s5 ws s6 ws s7 the miocene pleistocene full glacial climate regime 11 1 ma sparse borehole data from odp leg 113 and shaldril constrain the ages of the upper three seismic units and seafloor spreading magnetic anomalies compiled from literature constrain the basement ages in the presented age model the new horizons and stratigraphy often contradict local studies and show an increase in age from southeast to the northwest the up to 1130 m thick pre glacial seismic units form a mound in the central weddell sea basin and in conjunction with the eroded flank geometry allow the interpretation of a cretaceous proto weddell gyre bottom current the base reflector of the transitional seismic unit has a model age of 26 6 15 5 ma from southeast to northwest suggesting similar southeast to northwest initial ice sheet propagation to the outer shelf we interpret an eocene east antarctic ice sheet expansion oligocene grounding of the west antarctic ice sheet and early miocene grounding of the antarctic peninsula ice sheet the transitional regime sedimentation rates in the central and northwestern weddell sea 6 10 cm ky are higher than in the pre glacial 1 3 cm ky and full glacial regimes 4 8 cm ky the pre glacial to glacial rates are highest in the jane and powell basins 10 12 cm ky total sediment volume in the weddell sea deep sea basin is estimated at 3 3 3 9 106 km3

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

the role of diffusion during carbonate diagenesis abstract the dissolution reprecipitation process which characterizes the early mineralogical stabilization of carbonate sediments takes place in a somewhat open chemical system studies of the trace element chemistries and isotopic compositions of carbonate grains before and after stabilization have documented the exchange of ions between the diagenetic site and the aquifer solution if the pores at reaction zone and in the immediate neighborhood of the diagenetic site are of insufficient diameter to allow effective solution flow the exchange of ions between the diagenetic site and the aquifer solution the large volume of water which flows through the macropores of the carbonate sediment takes place by aqueous diffusion this paper examines diffusion applied specifically to the conditions of carbonate diagenesis the diffusion equation modified to these circumstances serves as a guide to understanding the diffusion process at a given temperature three variables determine the efficacy of diffusion the diffusion coefficient the pore path and geometry and the concentration gradient the diffusion coefficient may be considered a measure of the inherent velocity at which a given ion travels under standard conditions the double positive cations common in carbonates ca2 sr2 ba2 zn2 mg2 etc and the carbonate anion all have similar diffusion coefficients thus this term of the equation exerts little influence during normal carbo ate diagenesis the pore path and geometry refer to the distance from aquifer to reaction zone and the diameter shape and directness of the pore passage this term is difficult to quantify in diagenetic systems but is constant for different ions at a single diagenetic site the longer and the more complex the path the less effective diffusion is there is a general facies dependence to this term grainstones have short paths from reaction zone to aquifer due to their permeability whereas mudstones and wackestones are characterized by long and torturous paths through the mud grains to the aquifer solution exchange of ions in the fast situation is more effective than in the second the concentration gradient the difference between the concentration of an ion in th reaction zone and in the proximal aquifer solution is the most variable parameter in diffusion the sign of the gradient which may be positive or negative indicates the direction of diffusion transport of the ions toward the region of lower concentration one cation may diffuse from the reaction zone while simultaneously a second cation diffuses toward the reaction zone this two way traffic has been documented in diagenetic calcite corals sr2 diffuses away from and mg2 diffuses toward the diagenetic site additionally one cation may diffuse effectively whereas a second diffuses ineffectively the latter species being characterized by a weaker concentration gradient thus a given diagenetic site may be chemically open for one cation and simultaneously somewhat closed for another application of diffusion principles to the aragonite calcite transformation during early diagenesis indicates the compositions of solutions and diagenetic calcites undergo temporal changes early on with few active diagenetic sites sr2 diffuses effectively from the reaction zone to the aquifer since there is a steep concentration gradient diagenetic calcites are relatively low in sr2 because of its effective removal from the diagenetic site as the number of active diagenetic sites increases so much sr2 may be delivered to the aquifer that sr2 builds up in the aquifer solution and the concentration gradient shallows diffusion from individual sites becomes less effective sr2 concentrates in the reaction zone and diagene ic calcites enriched in sr2 are produced as more and more aragonite is consumed a final phase is reached in which less total sr2 is delivered to the aquifer and the system returns to the conditions characteristic of the early phase