geology and tectonics of the betic zone se spain abstract the southern margin of the iberian continent comprises a complex geological history which can be traced back into the proterozoic when a gneissic basement was formed a cover of nevado filabride rocks was deposited onto this proterozoic basement during the palaeozoic the permian intrusion of the bedar granite suggests that the palaeozoic sedimentary rocks now exposed in the betic cordilleras have been affected by the hercynian orogeny similar to that of palaeozoic rocks in the adjoining ossa morena zone the hercynian basement was probably covered by alpujarride carbonates in the mesozoic when rifting opened tethys and intruded 140 ma old basic dyke swarms the palaeozoic basement of the betic cordilleras comprises a suture of late cretaceous subduction 80 85 ma b p this can be inferred from hp lt metamorphic facies obducted in coeval thrust slices of nevado filabride rocks the nevado filabride nappes include mesozoic carbonates transformed into marbles macael the suture was probably annnealed after the closure of tethys the mesozoic boundary between africa and europe and the rifting in tethys ceased during the palaeogene when the atlas mountains were formed 36 ma b p subsequently relative movements between africa and europe in the neogene were accommodated by strike slip faults these define the iberian microplate moving eastward by atlantic spreading and possibly subducting under italy neogene deformation of iberia is most intensive in southeastern spain due to emplacement of a mantle diapir under the alboran area this occurred early in the neogene aquitanian and caused nappe spreading involving alpujarride and malaguide rocks the subsequent neogene history has now been studied in great detail and is reviewed here it involves clear examples of calc alkaline volcanism most probably not related to subduction seismic motion along strike slip faults within the iberian microplate and syntectonic deposition in intermontane neogene basins

palaeoclimatic implications of the occurrence of the arcoid bivalve anadara trapezia deshayes in the quaternary of australasia abstract the arcoid bivalve anadara trapezia deshayes 1840 is a eurythermal estuarine mollusc that flourishes at present in eastern australia between port phillip bay victoria and townsville in northern queensland a trapezia first appeared in the australian quaternary fossil record during oxygen isotope stage ois 7 in new zealand where it is now extinct the earliest known occurrences are in the rangitawa fossil beds and in uppermost castlecliffian strata west of wanganui north island ois 11 ca 400 ka the species had an extensive distribution during the last interglacial maximum ois 5e in both australia and new zealand and appears to have had a slightly wider than present geographic range in southeastern australia during the middle holocene as shown by records from tasmania and western victoria where it no longer lives apart from an isolated population inhabiting oyster harbour western australia a trapezia has not been confirmed living in coastal waters west of port phillip bay victoria it became extinct in new zealand sometime after ois 5e the extensive distribution and abundance of a trapezia and other fauna of subtropical affinity during the last interglacial maximum in areas where both are now extinct appears to be associated with an enhanced leeuwin current at that time coinciding with higher less seasonally concentrated levels of precipitation and river discharge the arrival of a trapezia in australasian coastal waters may have been a consequence of planktonic dispersal from southern south america a bravardi del rio from the middle miocene puerto madryn formation on the valdes peninsula argentina may be a possible ancestor for a trapezia

th u disequilibrium dating of middle and late pleistocene wood and shells from banks and victoria islands arctic canada an attempt has been made at dating middle and late pleistocene deposits from banks and victoria islands using the th u disequilibrium method geological correlations are difficult to establish because of the discontinuous nature of the terrestrial units and the relative absence of datable fossil wood and shells the th u geochemical system likely remained closed for extended periods because of the presence of permafrost which implies very limited or absent water circulation the th u age determinations obtained confirmed the previously established stratigraphic framework and provide chronological information in that samples of sangamonian age are differentiated from those that are younger wisconsinan and holocene or older middle pleistocene the th u disequilibrium method carefully used in areas where water circulation is limited can thus provide chronological control for sediments older than those that can be dated by the radiocarbon method

fault generated mountain fronts in southeast spain geomorphologic assessment of tectonic and seismic activity abstract tectonic activity of se spain is evaluated through the application of a general morphometric analysis over 17 different mountain fronts the selected fronts are distributed along the two most prominent crustal scale structures of the mediterranean sector of spain the eastern betic shear zone ebsz and the valencia trough geomorphic indexes used in this study are mountain front sinuosity index smf and valley floor width ratio vf this work is largely based on the smf vf regression analysis of the studied fronts together with previous available data from sw usa the development of mountain fronts in both different lithologies and tectonic contexts enabled characteristic morphometric signatures for different activity scenarios tectonic activity classes to be obtained this study thus indicates that variations of mountain front geomorphology triggered by different styles of faulting can be detected by morphometric analysis it is demonstrated that discrete uplift rates of 0 15 0 08 m ka are sufficient to keep relatively low smf values down to 1 4 in active fronts class 1 taking into account the reported uplift rates and preliminary palaeoseismic data for some of the class 1 studied fronts recurrence periods for surface rupture events can be theoretically bracketed for se spain recurrence periods for class 1 fronts could theoretically range between 10 000 and 12 500 years for maximum slip conditions and 1750 and 2600 years for minimum slip conditions inactive fronts class 3 develop under uplift rates down to 0 03 m ka and tested recurrence intervals for rupture events range between 25 000 and 50 000 years class 2 fronts of intermediate characteristics and activity display uplift rates between 0 07 and 0 03 m ka

th u dating of strombus bubonius bearing marine terraces in southeastern spain single dates obtained on mollusk shells by the u series nuclides method are highly unreliable primarily because of the mobility of uranium isotopes however in several cases a statistical approach was demonstrated to yield coherent chronologies in both continental and marine environments the authors report on 34 new th and u isotope measurements on strombus bubonius and glycymeris glycymeris fossils from raised marine terraces in the almeria area southeastern spain the results yield a coherent chronology that indicates the presence of the warm water s bubonius fauna in the mediterranean basin reconsideration of the tyrrhenian stratigraphy based on the presence of s bubonius is thus required

reply to the comments by mauz b and antonioli f on sea level and climate changes during ois 5e in the western mediterranean we really appreciate the comments by mauz and antonioli on our paper bardaji et al 2009geomorphologic maps are often lacking in studies related to the reconstruction of past sea level changes in most cases these maps would be the only way of reconstructing past sea level oscillations see for example but here we respond to the erroneous statements made in their critical reading of our work we agree with the authors historic review of the problems raised when effects of tectonics and sea level oscillations are observed in the record of relative sea level changes in western mediterranean we should not forget that the mediterranean itself constitutes a collision plate boundary with few stable areas within it therefore the study of the last interglacial shorelines cannot be simply analysed according to altitude as they say what we do not share with mauz and antonioli is that the only solution to this seemed to be determining the age of a coastal deposit using radiometric dosimetric and chemical dating techniques it is obvious that we need a chronological approach to be as accurate as possible first of all however an exhaustive field analysis is needed and this is overlooked by mauz and antonioli at least in the spanish mediterranean sector to begin with field analysis would yield a deeper wider geological knowledge not only of the precise sections but also on a regional scope second a geomorphologic understanding of the selected sections is necessary geomorphology is the best tool that enables us to understand how many different sea level highstands or intervals we are dealing with in terms of their relation to former and younger sea level indicators i e 3d stratigraphic architecture sampling for dating purposes can only be done when the sedimentary sequence is clear and after detailed geomorphologic mapping unfortunately radtke and schellmann 2004

evidence for sea level oscillations by the characteristic thickness of marine deposits from raised terraces of southern calabria italy abstract clastic deposits associated with marine terraces can provide evidence for detecting eustatic oscillations the method is based on the characteristic thickness ct of beach formations which are generally deposited on a wave cut platform between the breakpoint and the swash upper limit on any present day coast ct reflects equilibrium related to current shore processes with a constant sea level it represents a local threshold t cr as when sea level rises ct increases by a value equal to the rise amplitude this amount is reduced in uplifted areas by the magnitude of coeval uplifting the amplitude of sea level variations detected by ct can be calculated knowing ct t cr uplift rate and the duration of an oscillation the method is applied to the clastic deposits of 23 marine terraces stepped between 52 and 172 m and shaped over the mis 5 mis 4 period along the calabria coast of the messina strait not only the great orbital oscillations mis 5 5 mis 5 3 mis 5 1 and mis 3 are recorded but also several rapid and low amplitude events are detected into each substage the most surprising result is the ten small oscillations during mis 5 5 the duration of which ranges between 2 ka and less than 1 ka while sea level oscillates from 0 5 to 12 m in amplitude by calculating initial relative sea level highstands and also lowstands preceding them detailed eustatic oscillations of the curve are drawn

inclusion of topological measurements into analytic estimates of effective permeability in fractured media we demonstrate how topology based measures of connectivity can be used to improve analytical estimates of effective permeability in 2 d fracture networks which is one of the key parameters necessary for fluid flow simulations at the reservoir scale existing methods in this field usually compute fracture connectivity using the average fracture length this approach is valid for ideally shaped randomly distributed fractures but is not immediately applicable to natural fracture networks in particular natural networks tend to be more connected than randomly positioned fractures of comparable lengths since natural fractures often terminate in each other the proposed topological connectivity measure is based on the number of intersections and fracture terminations per sampling area which for statistically stationary networks can be obtained directly from limited outcrop exposures to evaluate the method numerical permeability upscaling was performed on a large number of synthetic and natural fracture networks with varying topology and geometry the proposed method was seen to provide much more reliable permeability estimates than the length based approach across a wide range of fracture patterns we summarize our results in a single explicit formula for the effective permeability

connectivity permeability and channeling in randomly distributed and kinematically defined discrete fracture network models a major use of dfn models for industrial applications is to evaluate permeability and flow structure in hardrock aquifers from geological observations of fracture networks the relationship between the statistical fracture density distributions and permeability has been extensively studied but there has been little interest in the spatial structure of dfn models which is generally assumed to be spatially random i e poisson in this paper we compare the predictions of poisson dfns to new dfn models where fractures result from a growth process defined by simplified kinematic rules for nucleation growth and fracture arrest davy et al 2010 2013 this so called kinematic fracture model is characterized by a large proportion of t intersections and a smaller number of intersections per fracture several kinematic models were tested and compared with poisson dfn models with the same density length and orientation distributions connectivity permeability and flow distribution were calculated for 3d networks with a self similar power law fracture length distribution for the same statistical properties in orientation and density the permeability is systematically and significantly smaller by a factor of 1 5 to 10 for kinematic than for poisson models in both cases the permeability is well described by a linear relationship with the areal density p32 but the threshold of kinematic models is 50 larger than of poisson models flow channeling is also enhanced in kinematic dfn models this analysis demonstrates the importance of choosing an appropriate dfn organization for predicting flow properties from fracture network parameters

climate and vegetation changes 180 000 to 345 000 years ago recorded in a deep sea core off portugal a new high resolution combined marine proxy pollen sequence from the portuguese margin md01 2443 enables direct comparison of ocean and ice volume changes with vegetation development in south west iberia during marine isotope stages mis 7 8 and 9 changes in sea surface conditions on both orbital and millennial time scales are closely mirrored by forest extent indicating a coherence of climate variability between the north atlantic and south west iberia deglacial warming at the start of mis 7 and 9 was interrupted by incursions of subpolar water masses at the site accompanied by reversals in tree population expansion during mis 7e and 9e the close relationship in timing and amplitude between vegetation and offshore conditions broke down early forest collapse points to pronounced cooling and aridification on land which although not accompanied by a change in water masses at the portuguese margin appears to have coincided with abrupt decreases in atmospheric methane concentration recorded in antarctic ice cores the most extreme glacial conditions of mis 8 occurred during the early part followed by an interval of warmer conditions and tree population expansion similar to 263 ka this has sometimes been considered as indicating an early deglaciation but the data presented here show that it was distinct from termination iii which occurred later in line with milankovitch forcing a sub orbital oscillation in both isotopic and pollen records is observed at the end of mis 7 ca 184 ka which appears to be coeval with a recently identified sea level high stand c 2006 elsevier b v all rights reserved

the impact of quaternary sea level and climatic change on coastal alluvial fans in the cabo de gata ranges southeast spain conventionally a fall in base level is seen as stimulating incision into the distal zones of alluvial fans in the cabo de gata ranges of southeast spain evidence exists to the contrary two sets of quaternary coastal alluvial fans demonstrate the interaction between climatically driven variations in the supply of sediment and eustatically driven changes in base level the fans are supplied from miocene volcanic terrain within which no evidence can be found for major tectonic deformation during the period of fan development the evolution of the east coast fans has been affected by variations in sediment supply and changes in sea level the west coast fans were buffered from the effects of changes in sea level by coastal barriers three phases of past sedimentation can be identified on the fans these can be differentiated on the basis of field observations of soil profiles particularly colour of the b horizons and accumulation of caco3 and laboratory analyses of sequential iron oxide extractions and magnetic mineral properties the two earlier major sedimentation phases were coincident with global glacials ca 135 ka and ca 85 10 ka based on the stratigraphy and uranium thorium dating of the coastal sediments high sea levels during the intervening interglacial and during the holocene caused erosion of the distal zones of the east coast fans which led to channel incision into the fan surfaces on the west coast fans no such incision occurred simply proximal incision by small fanhead trenches the youngest relatively minor phase of fan sedimentation has occurred during the holocene these contrasting contexts have produced differing styles of fans with telescopic fan morphology on the east coast and stacked morphology on the west coast fans the differences are reflected in the fan profiles with steeper gradients dominating the east coast fans and extensive lower gradient distal surfaces on the west coast fans fan morphometry based on analysis of the residuals from drainage area to fan area and gradient regressions also differentiates between the fan contexts the fan building phases appear to be controlled proximally by climatically driven pulses of sediment supplied to the fans these occurred during global glacials coincident with low sea levels and caused fan progradation onto the exposed foreshore the intervening global interglacials were times of little fan sedimentation and on the east coast where high sea levels were able to erode the fan toes deep through fan dissection ensued

the penultimate interglaciation of northern russia abstract this paper presents new field and laboratory data combined with previously published materials on interglacial sediments underlying two upper tills of northern european russia and west siberia the emphasis is on the structure and chronometric data of marine strata with shells of boreal molluscs of cyrtodaria genus indicative of the atlantic marine invasion into these sedimentary basins during the late middle pleistocene another line of evidence for this time span is inferred from inter till terrestrial sequences in the european northeast with forest pollen spectra suggesting a climate much warmer than today the decisive correlation signal is provided by optically stimulated luminescence and electron spin resonance dates indicating mis 7 time and by the geological position of two interglacial formations between the first second and third from the surface glacial complexes the collected evidence disagrees with the model of the unique boreal transgression and confirms that saline atlantic water at least twice invaded northern russia during the last 250 kyears the sedimentary formations of the penultimate interglaciation can serve as a new intra regional stratigraphic marker for the northern pleistocene

new evidence for vegetation development and timing of upper middle pleistocene interglacials in northern germany and tentative correlations abstract this paper discusses palynological investigations and new 230th u ages of two upper middle pleistocene sequences of the formerly glaciated northern german lowlands the reinsdorf sequence at the open mine of schoningen lower saxony and the north friesian site of leck new 230th u ages of late interglacial organic layers of the archaeological lake margin site of the reinsdorf sequence ranging from 280 to 343 ka give evidence for a correlation of those deposits with marine isotope stage mis 9 near and long distance correlation by means of palynological investigations of holsteinian and related interglacial continental deposits and their correlation with the mis is discussed isotopic investigations of uranium and thorium from organic rich mud deposits at core leck 8 point to an open system and age estimation by 230th u dating remains therefore unclear compared to other upper middle pleistocene warm periods in north germany correlations of the leck interglacial with the holsteinian and the reinsdorf interglacial can be excluded in comparison with sediment successions from the nachtigall section at hoxter and the section ottostrase at gottingen the leck interglacial is discussed as a correlative of a warm temperate phase of mis 7

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

a calcrete based u th chronology for landform evolution in the sorbas basin southeast spain nodular and massive calcretes from alluvial terraces in the sorbas area of southeast spain have been dated by the u th isochron method to between 8 350 ka alternative approaches have been used to generate the multiple samples for the isochron method for several of the calcretes dates agreed closely when obtained by total dissolution of a number of nodules or by the sequential dissolution in different acids of a single nodule however fractional dissolution of a single nodule in the same acid revealed two stages of precipitation of different age it is considered that the calcretes may not be strictly pedogenic in origin and that groundwater processes linked to the alluvial environment may have been involved also nevertheless their dates provide minimum ages for a chronostratigraphic framework for terrace evolution

ice dammed lakes and rerouting of the drainage of northern eurasia during the last glaciation during the quaternary period ice sheets centred over the barents and kara seas expanded several times onto mainland russia and blocked northflowing rivers such as the yenissei ob pechora and mezen large ice dammed lakes with reversed outlets e g toward the caspian sea formed south of these ice sheets some lakes are reconstructed from shorelines and lacustrine sediments others mainly from ice sheet configuration ice dammed lakes considerably larger than any lake on earth today are reconstructed for the periods 90 80 and 60 50 ka the ages are based on numerous optically stimulated luminescence osl dates during the global last glacial maximum lgm about 20 ka the barents kara ice sheet was too small to block these eastern rivers although in contrast to the 90 80 and 60 50 ka maxima the scandinavian ice sheet grew large enough to divert rivers and meltwater across the drainage divide from the baltic basin to the river volga and that way to the caspian sea climate modelling shows that the lakes caused lower summer temperatures on the continent and on the lower parts of the ice sheet the final drainage of the best mapped lake is modelled and it is concluded that it probably emptied within few months we predict that this catastrophic outburst had considerable impact on sea ice formation in the arctic ocean and on the climate of a much larger area c 2003 elsevier ltd all rights reserved less

autocompaction in holocene coastal back barrier sediments from south devon southwest england uk abstract the present day elevation of superficial horizons situated above a competent basal stratum is likely to be lower than the original height of deposition this is because sediments such as minerogenic fines and peat undergo a post depositional reduction in volume as a result of the weight of overlying sediments the downward movement being due to the cumulative compression of all the sediment below the level in question this autocompaction can affect the palaeoenvironmental interpretation of lithofacies from which a vertical reference is required e g when quantifying the height of a sea level index point geotechnical theory was used to apply a correction to holocene coastal back barrier sediments from north sands and blackpool sands in south devon uk and so to return marker horizons to a level approximating their original height of deposition in this model the total downward movement is calculated by notionally dividing the underlying soil into a number of thin 0 1 to 0 2 m layers and calculating the individual compression in each one the results were then summed to give the total compression this approach can underestimate the full extent of autocompaction notably due to uncertainties arising from the behaviour of organic rich facies and from inadequate knowledge of groundwater history the results must be considered semiquantitative and are usually minimum estimates results of vertical corrections from coastal sedimentary units in south devon range from 1 m at contacts between minerogenic sediments and peat increasing to 2 m in more organic facies

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

an arctic perspective on dating mid late pleistocene environmental history to better understand pleistocene climatic changes in the arctic integrated palaeoenvironmental and palaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologic age control are required not least for correlation to extra arctic records in this paper we discuss from an arctic perspective methods and correlation tools that are commonly used to date arctic pleistocene marine and terrestrial events we review the state of the art of arctic geochronology with focus on factors that affect the possibility and quality of dating and support this overview by examples of application of modern dating methods to arctic terrestrial and marine sequences event stratigraphy and numerical ages are important tools used in the arctic to correlate fragmented terrestrial records and to establish regional stratigraphic schemes age control is commonly provided by radiocarbon luminescence or cosmogenic exposure ages arctic ocean deep sea sediment successions can be correlated over large distances based on geochemical and physical property proxies for sediment composition patterns in palaeomagnetic records and increasingly biostratigraphic data many of these proxies reveal cyclical patterns that provide a basis for astronomical tuning recent advances in dating technology calibration and age modelling allow for measuring smaller quantities of material and to more precisely date previously undatable material i e foraminifera for c 14 and single grain luminescence however for much of the pleistocene there are still limits to the resolution of most dating methods consequently improving the accuracy and precision analytical and geological uncertainty of dating methods through technological advances and better understanding of processes are important tasks for the future another challenge is to better integrate marine and terrestrial records which could be aided by targeting continental shelf and lake records exploring proxies that occur in both settings and by creating joint research networks that promote collaboration between marine and terrestrial geologists and modellers

climatic variability of marine isotope stage 7 direct land sea ice correlation from a multiproxy analysis of a north western iberian margin deep sea core abstract the direct land sea ice correlation performed in the north western iberian margin core md01 2447 shows that marine isotope stage 7 mis 7 is marked by an alternation of five warm and cold periods this climatic variability is in general synchronously detected in marine and terrestrial realms by our record termination iii is marked by three cold episodes the last one interrupts the forest development in north western iberia related to the deglacial climatic amelioration it begins in the middle of termination iii but the maximal cold conditions occur at the beginning of low ice volume conditions mis 7 is characterised by three periods of very low ice volume associated with marine and continental high temperatures in and off north western iberia the correlation of our record with odp site 980 shows that the climatic variability detected in the north western iberian region has also an imprint in northern north atlantic it also highlights that most of the cold periods are associated with iceberg discharges in the north atlantic the comparison of the north western iberian margin sequence with the long european pollen records has allowed refining the correlation of the marine and continental stratigraphy for mis 7

the plio pleistocene boundary in southeast spain a review the plio pleistocene boundary in the mediterranean region has been defined by the entry of the so called northern guests the absence of this characteristic cold fauna in the sedimentary record of littoral marine basins in se spain has led to the local establishment of this boundary by other means most outcropping upper pliocene and pleistocene marine sediments in this area have a very shallow character resulting in the absence of the planktonic foraminiferal assemblages that characterize the upper pliocene as a result the only means of determining this boundary has been through regional correlation detailed mapping and sedimentological analysis as well as palaeomagnetism after studies were carried out in different basins and accepting the age of 1 64 now recalibrated to 1 8 ma for the plio pleistocene boundary aguirre and pasini 1985 we conclude that this boundary does not bear any climatic environmental or tectonic signature the changes in most of these basins seem to occur either before or after this date

late quaternary ice sheet history of northern eurasia the maximum limits of the eurasian ice sheets during four glaciations have been reconstructed 1 the late saalian 140 ka 2 the early weichselian 100 80 ka 3 the middle weichselian 60 50 ka and 4 the late weichselian 25 15 ka the reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in russia and siberia and with marine seismic and sediment core data the barents kara ice sheet got progressively smaller during each glaciation whereas the dimensions of the scandinavian ice sheet increased during the last ice age the barents kara ice sheet attained its maximum size as early as 90 80 000 years ago when the ice front reached far onto the continent a regrowth of the ice sheets occurred during the early middle weichselian culminating about 60 50 000 years ago during the late weichselian the barents kara ice sheet did not reach the mainland east of the kanin peninsula with the exception of the nw fringe of taimyr a numerical ice sheet model forced by global sea level and solar changes was run through the full weichselian glacial cycle the modeling results are roughly compatible with the geological record of ice growth but the model underpredicts the glaciations in the eurasian arctic during the early and middle weichselian one reason for this is that the climate in the eurasian arctic was not as dry then as during the late weichselian glacial maximum

late holocene sea levels in ireland the course of irish sea levels during the late holocene is not well known yet it is an understanding of this period that will prove crucial in the definition and management of future sea level changes the coastline of ireland embraces wide environmental and glacio isostatic contrasts which serve and to some extent control sea level events at both local and regional scales making definitive resolution of relative sea level changes difficult in the southwest the picture is of inexorable relative sea level rise studies in co kerry show a gradual submergence of terrestrial facies by estuarine and in places marine materials pollen and diatom studies together with 14c dates suggest a decreasing rate of relative sea level rise in the last 2500 years often associated with geomorphological changes sites on the south coast of ireland confirm the evidence from the southwest in cork harbour recent relative sea level rise since 2100 bp was responsible for marginal land submergence while elsewhere rising water levels appear to have caused rapid barrier migrations and coast erosion palaeoenvironmental evidence from this region suggests a distinctive pattern of sea level change associated with sedimentary and or crustal dynamics which is not encountered elsewhere in northwest europe the overall rate of relative sea level change on the south and southwest coasts falls between 0 6 and 1 1 mm year over the last 5000 years in the north there is a clear east to west variation in relative sea level trends following an isostatically controlled peak 3 to 1 m od between 6500 bp east and 3500 bp west falling sea levels from 3500 to 1500 bp have been followed by a general slow rise although there are still local anomalies to this pattern most noticeably at malin head where sea level is currently falling at 2 4mm year relative sea level signatures in ireland differ markedly between the north and south coasts furthermore geomorphological and ecological contexts of this rise vary from east to west providing a complex all ireland framework for future investigations

the distribution of carbonate eolianite abstract carbonate eolianite forms distinctive coastal landforms on many mid latitude continents and islands numerous studies of extensive continental and smaller island deposits in both hemispheres have shown the eolianites are predominantly pleistocene in age the coorong coastal plain of south australia contains the world s longest record of eolianite deposition revealing that major phases of carbonate accumulation occurred during interglacial and some interstadial sea level highstands throughout the quaternary similarly the well studied eolianite islands of bermuda and the bahamas record a close match between dune accretion and sea level highstands since the middle pleistocene several other eolianite deposits appear to have formed at least partially during glacial periods the glacial age deposits are eolian reworked relict shelf or coastal sediments or remnants of former highly mobile coastal dunes sourced from low sea level shorelines the distribution and bioclastic composition of large scale eolianite deposits suggests carbonate production on shallow shelves and banks is the ultimate control on the formation of eolianite the bulk of the carbonate comprising those eolianites is heterozoan being produced where there is low terrigenous sediment input in dominantly temperate cool water and subtropical carbonate provinces quaternary cyclical movements of sea level have also controlled the form and rate of coastal carbonate deposition with repeated pulses of sedimentation during highstands forming laterally coalesced vertically stacked or composite dune successions major unconformities within the deposits are marked by paleosols which record hiatuses in coastal sedimentation in several regions major eolianite units overlie coastal deposits of terrigenous sediment those successions suggest that the trend towards aridity and reduction in the supply of terrigenous sediment to shelves during the quaternary has enhanced the production of carbonate and the deposition of eolianite

coastal evolution in south west england united kingdom an enhanced reconstruction using geophysical surveys abstract the coastline of south devon south west england is believed to be subsiding faster than any area in the united kingdom uk current estimates are based however on very limited holocene relative sea level rsl and lithostratigraphic data there is therefore an urgent need for more information to improve our understanding of coastal evolution in the region sediment coring from slapton sands and blackpool sands in south east devon provides material for interpreting land and sea level changes further stratigraphic mapping was carried out using 2d electrical resistivity tomography ert of the near surface this method of geophysical survey ground truthed with borehole data has rarely been used for palaeoenvironmental reconstruction but provided useful results here models of holocene coastline evolution based on those from the eastern usa show that sea level in start bay was 17 m below present rsl ca 9000 cal yr bp a barrier lagoon system was forced landward by seas rising at 5 m ka across substrates comprised of weathered slate and shale thick deposits of minerogenic fines 10 m at slapton sands were identified in cores and mapped using the ert survey method barrier lagoons became choked by sediment when rsl was 5 m below present at ca 4400 cal yr bp and reached their current configuration during the late holocene ert results show that the slapton sands modern day barrier complex is a uniform 9 m thick for a longshore distance of at least 1 5 km

pollen analytical biostratigraphy of the last five climatic cycles from a long continental sequence from the velay region massif central france in the volcanic region of velay massif central france lake sediment sequences derived from maar craters situated close to one another ribains praclaux and lac du bouchet have been correlated on the basis of tephrostratigraphical analyses this has enabled the construction of a sequence 2980 pollen spectra that begins during the glaciation preceding the holsteinian and ends in the present this sequence covers the period from 450 ka i e from the end of marine oxygen isotope stage 12 to the present time and includes five climatic cycles the study of a second core from the praclaux site completed the long velay sequence the biostratigraphy of the whole sequence is described in detail and illustrated by a synthetic and simplified pollen diagram thirteen temperate forest episodes interglacials or interstadials and as many cold periods glacials or stadials are defined each temperate episode is characterised by particular forest development and vegetation dynamics and all of them with the exception of the holocene begin and end with a pinus forest the vegetation dynamics observed during the holocene resemble more closely those recorded during the interstadials than during the interglacials copyright 2000 john wiley sons ltd

sequences of quaternary marine levels in elche basin eastern betic cordillera spain detailed mapping of the coastal areas of the basin of elche revealed complex successions of marine quaternary terraces attached to the tectonically generated positive reliefs of santa pola los arenales del sol and la marina structural data and lateral facies relationships suggest active tectonics in this area since early pleistocene times with e w trending anticlinal folding and n s normal faulting these events strongly influenced both the occurrence of positive levels and the distribution of paleocliffs dug by waves in this way staircased marine terraces were generated following the gentle progressive uplifting of these reliefs the most complete sequence of terraces la marina includes three strombus bubonius bearing tyrrhenian marine units that can be compared to similar units in santa pola where the oldest one contains patella ferruginea only

a petrological and geochemical study of the calcareous sandstone of west african marine pleistocene cap des biches senegal abstract in senegal the marine pleistocene is represented by several outcrops of calcareous sandstone slabs which underly the recent sandy shoreline south of dakar these outcrops show dissolution and recrystallization phenomena increasingly evident as one moves south they disappear at toubab dialao i e approximately 40 km from dakar the outcrop at cap des biches has been studied mainly because of the exceptional preservation of some ostrea calcitic tests which allowed isotopic u th measurements this outcrop of metric thickness was subjected to petrographic and mineralogical examination and to several geochemical analyses trace elements stable isotopes amino acids which lead to the conclusion that the base of the deposit has been preserved two u th apparent ages obtained 178 ka and 240 ka are older than the only age of the isotopic stage 5c obtained in the area a post depositional mobility of u cannot be rejected and ages may not be reliable however a minimal age considerably older than finite 14c ages previously published may be proposed eemian interglacial i e isotopic stage 5 in these environments geochemical analyses show high pleistocene sea levels of either warmer and or more diluted waters than the present levels i e a probable northern extension of guinean waters

fracture size and transmissivity correlations implications for transport simulations in sparse three dimensional discrete fracture networks following a truncated power law distribution of fracture size we characterize how different fracture size transmissivity relationships influence flow and transport simulations through sparse three dimensional discrete fracture networks although it is generally accepted that there is a positive correlation between a fracture s size and its transmissivity aperture the functional form of that relationship remains a matter of debate relationships that assume perfect correlation semi correlation and non correlation between the two have been proposed to study the impact that adopting one of these relationships has on transport properties we generate multiple sparse fracture networks composed of circular fractures whose radii follow a truncated power law distribution the distribution of transmissivities are selected so that the mean transmissivity of the fracture networks are the same and the distributions of aperture and transmissivity in models that include a stochastic term are also the same we observe that adopting a correlation between a fracture size and its transmissivity leads to earlier breakthrough times and higher effective permeability when compared to networks where no correlation is used while fracture network geometry plays the principal role in determining where transport occurs within the network the relationship between size and transmissivity controls the flow speed these observations indicate dfn modelers should be aware that breakthrough times and effective permeabilities can be strongly influenced by such a relationship in addition to fracture and network statistics this article is protected by copyright all rights reserved

holocene coastal evolution and sea level change on the southern coast of england a review data collected recently from select areas within the eastern central and western english channel are used to reconstruct the holocene evolution and sea level history of the southern coast of england rapid sea level rise in the early holocene produced a ubiquitous vertical and lateral expansion in the marine influence from ca 6800 cal calendar yr bp the rate of sea level rise declined and a shift from minerogenic to organogenic sedimentation is also widely recorded a further decline in the rate of sea level rise occurred in the late holocene during which time the eastern and central english channel experienced coastal inundation and a return to minerogenic sedimentation explanations for this apparent contradiction include the effects of this decline on the accumulation of minerotrophic peat and changes in sediment supply sea level index points from the eastern channel generally plot below those from the central and western channel indicating differential crustal movement although sediment compaction and tidal range also may be responsible for apparent altitudinal variation between these areas despite an increase in the quantity and quality of the data available from this region over the past 20 yr these and a number of other important issues require further clarification copyright 2003 john wiley sons ltd

a variable aperture fracture network model for flow and transport in fractured rocks a three dimensional variable aperture fracture network model for flow and transport in fractured rocks was developed the model generates both the network of fractures and the variable aperture distribution of individual fractures in the network before solving for the flow and transport of the whole network a library of single fracture permeabilities and particle transport residence time spectra is first established the spatially varying aperture field within an individual fracture plane is constructed by geostatistical methods then the flow pattern the fracture transmissivity and the residence times for transport of particles through each fracture are calculated the library of transmissivities and frequency distributions of residence times is used for all fractures in the network by a random selection procedure the solution of flow through the fracture network and the particle tracking calculation of solute transport for the whole network are derived from one side of the network to the other the model thus developed can handle flow and transport from the single fracture scale to the multiple fracture scale the single fracture part of the model is consistent with earlier laboratory tests and field observations the multiple fracture aspect of the model was verified in the constant aperture fracture limit with an earlier code the simulated breakthrough curves obtained from the model display dispersion on two different scales as has been reported from field experiments

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

uranium concentration and isotope ratio profiles within mercenaria shells geochronological implications shells of nineteen specimens of mercenaria from unconsolidated sediments of the southeastern usa coast ranging in age from alive to pliocene were each separated into three to six sections parallel to the shell surface the uranium concentration and isotope ratio of each subsample was determined the results confirm those of previous studies that whole fossil shells have about 8 times as much uranium 300 vs 40 ppb and considerably higher 234u 238u ratios than do whole live collected shells however it was also found that uranium concentrations fall very steeply by factors of 300 and 15 in live and fossil shells respectively from the exterior of the shell to about two thirds of the shell thickness between this depth and the interior surface the uranium concentrations of live shells increase by about a factor of 5 while fossils have gradients which vary from moderately positive to moderately negative the most surprising finding of the study is that the interior portions of the shells become closed chemical systems by no more than about 15 ka after their death this is known from the observation that these portions of late pleistocene shells still have oceanic uranium isotope ratios while the exterior portions of the same shells have ratios which reflect an uptake of uranium from continental groundwaters the water the shells have been in contact with for the vast majority of their existence thus the u series ages of the interior portions of mercenaria shells may be valid after a small correction though shells older than about 200 ka seem less promising firm conclusions cannot be drawn regarding them because of the great scatter in the data

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

middle pleistocene glaciations of the russian north abstract geological data on the pre eemian glaciations of northern russia including the latest results by the russian norwegian pechora project are synthesized in order to present evidence for comparison with other early glaciations around the arctic the bulk of evidence indicates that arctic and subarctic regions of european russia of western and central siberia during the middle pleistocene were at least 4 times covered by large ice sheets which advanced mainly from the shelf ice domes partly from fennoscandia and the putorana plateau ice accumulations in the ural mountains were insignificant and did not form any noticeable ice dispersal centres unlike the classical glaciated areas ice sheets of northern russia acted mainly on a soft perennially frozen substrate which was heavily glacitectonised the middle pleistocene ice sheets were much larger than the weichselian ones the fennoscandian ice dispersal centre was most active in northern european russia during the penultimate glaciation ois 6 when shelf centred ice domes were relatively weaker larger continental ice sheets were formed in preceding ice ages when kara sea ice dispersal centre dominated the lowland ice sheets reached their maximum extent at different stages from cromerian don glaciation in european russia to ois 8 in west siberia therefore the maximum ice limit is time transgressive in northern russia

understanding hydraulic fracturing a multi scale problem despite the impact that hydraulic fracturing has had on the energy sector the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres we characterize flow and transport in shale formations across and between these scales using integrated computational theoretical and experimental efforts methods at the field scale we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir at the core scale we use triaxial fracture experiments and a finite discrete element model to study dynamic fracture crack propagation in low permeability shale we use lattice boltzmann pore scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore scale flow and transport phenomena including multi phase flow and fluids mixing a mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs finally we discuss the potential of co2 as an alternative working fluid both in fracturing and re stimulating activities beyond its environmental advantages this article is part of the themed issue energy and the subsurface

glacial history and palaeo environmental change of southern taimyr peninsula arctic russia during the middle and late pleistocene abstract we here reconstruct a glacial and climate history of arctic nw siberia for the last 600 000 years based on the stratigraphy and chronology of 35 studied river sections on the southern taimyr peninsula from this stratigraphic mosaic we have identified four glacial events marked by tills glaciotectonics which are intercalated with mainly marine sediments deposited in proglacial settings during transitions from glacial conditions into subsequent interglacials interstadials the traces of early shelf based kara sea ice sheet ksis glaciations in marine isotope stages mis 12 14 and 8 are sparsely preserved but these ice advances are suggested to have terminated far south into the central siberian uplands as also was the case with the younger taz glaciation mis 6 the inception phase of the latter glaciation was complex with ice advancing into a proglacial marine basin both from the south putorana anabar uplands and the north the deglaciation leading into the karginsky interglacial mis 5e was marked by the development of the southernmost ice marginal zones imzs on the taimyr lowlands the urdakh and sampesa imzs the most recent late pleistocene glacial cycle is recorded by three successively smaller ksis advances from the kara sea shelf onto taimyr of which only the first during early zyryanka mis 5d reached south of the byrranga mountains with its maximum extent marked by the jangoda syntabul severokokorsky imz retreat of the ice margin during mis 5c b was accompanied by deposition of glaciomarine sediment in the proglacial basin and deposition of large successions of delta sediments in the foothills of the byrranga mountains reaching 100 m above present sea level the region north of the byrranga mountains was subjected to two subsequent ksis glaciations during mis 4 and mis 2 while the area south of the byrranga mountains transitioned to a terrestrial environment from the middle into the lower zyryanka as evidenced by deposition of fluvial aeolian and ice complex yedoma sediments

quaternary stratigraphy and paleogeography of the galilee coastal plain israel the quaternary deposits in the galilee coastal plain comprise alternating calcareous sandstone red loam dark clay and uncemented sand the calcareous sandstone in the lower part of the sequence represents a pliocene to early pleistocene marine transgression and is covered unconformably by the late quaternary sequence the base of this sequence has an estimated age of 500 000 yr it is covered unconformably by marine calcareous sandstone in the west which represents the global high sea level stand of isotope stage 7 1 and is known as one of the tyrrhenian events in the mediterranean area the overlying members represent the low sea level stand of stage 6 the first a red paleosol indicating a relatively wet phase and the second an eolianite unit representing a drier phase the eolianite forms longitudinal subparallel ridges that formed contemporaneously the overlying marine sandstone which contains one of the diagnostic fossils of the tyrrhenian events the gastropodstrombus buboniuslmk accumulated during the global high stand of stage 5 5 the last glacial period left no sedimentary record the holocene is represented by a marine clay unit that is covered by sand the present study establishes a complete and detailed chronostratigraphic sequence for an eastern mediterranean beach which contains the gastropods buboniuslmk s buboniuson the galilee coast is attributed to stage 5 5 and therefore establishes an east west mediterranean correlation which can be used for linking mediterranean events to paleo sea levels and global climate changes

luminescence dating of the stratzing loess profile austria testing the potential of an elevated temperature post ir irsl protocol abstract feldspar infrared stimulated luminescence irsl signals saturate at 2000 gy i e 500 700 ka assuming a dose rate of 3 4 gy ka typical for loess and it is therefore theoretically possible to date middle pleistocene loess however the accuracy of age estimates is hampered by anomalous fading which leads to significant age underestimation fading corrections have been proposed but these corrections are reliant on inherent assumptions and in any case are inapplicable at large doses as the growth curve approaches saturation recent studies have identified a post ir irsl signal that shows less fading and is thus less dependent on accurate fading corrections this study builds upon these investigations and applies a post ir irsl sar dating protocol to polymineral fine grain samples of the loess palaeosol sequence in stratzing lower austria after a preheat at 320 c 60 s and an ir bleach at 50 c 200 s irsl was measured at 290 c for 200 s the same set of conditions were used to measure the response to a test dose recycling ratios recuperation and dose recovery tests show that this protocol is suitable for the loess under investigation although finite residual doses of up to 20 gy are observed for the oldest samples the natural signal is in or close to saturation indicating that fading is negligible in nature this observation is inconsistent with the measured laboratory fading rates of 1 1 5 decade and needs further investigation

relative sea level change and postglacial isostatic adjustment along the coast of south devon united kingdom previous sea level studies suggest that southwest britain has the fastest subsiding coastline in the united kingdom but tide gauge data gps and gravity measurements and geophysical models show little evidence of anomalous subsidence in this region in this paper we present 15 new sea level index points from four coastal barrier systems in south devon eight are from compaction free basal sediments and others were corrected for autocompaction our data suggest that relative sea level along the south devon coastline has risen by 21 4 m during the past 9000 years sea level rise slowed during the middle and late holocene and a rise of 8 1 m has occurred since ca 7000 cal yr bp anomalous ages for many rejected points are attributed to sediment reworking during barrier transgression the relative sea level history during the early and middle holocene shows a good fit with geophysical model predictions but the geological and modelled data diverge in the later holocene unlike the geophysical models sea level index points cannot differentiate between late holocene relative sea level histories of south devon and southwest cornwall it is suggested that this discrepancy can be resolved by obtaining additional high quality sea level index points covering the past 4000 years copyright 2008 john wiley sons ltd

the reliability of uranium series mollusc dates from the western mediterranean basin abstract fossil mollusc shells from western mediterranean raised beach deposits have been dated using u series techniques sub sampling has allowed intra shell isotopic variability to be assessed although most of the calculated ages appear plausible and some internal consistency exists closer scrutiny of the data reveals that the shells have behaved as geochemically open systems and all the ages therefore must be considered suspect some previously published u series mollusc data from the same region may also contain evidence of open system behaviour and are considered equally unreliable simple modelling suggests considerable variation in isotopic uptake behaviour both within and between shells

last interglacial stratigraphy in the burg el arab region of the northwestern coast of egypt abstract the northwestern coast of egypt a stable carbonate platform is characterized by the presence of successive coastal ridges that extend parallel to the present shoreline study of marine deposits at the bottom of gebel maryut ridge from the drain cut of bahig together with analyses of core samples raised from four boreholes drilled in the el dekheilla depression to the depths of 10 15 m reveal the presence of two phases of beach boulders the lower older phase b b 1 wedge eolianites e 1 at an elevation of 3 4 m and show an average 18o of 0 82 the upper younger phase b b ii wedge eolianites e 2 at 6 7 m a s l with an average 18o of 1 5 these beach boulders are overlained by thick fossiliferous limestones and geosoils they record the last interglacial high sea level isotope substage 5e and aminozone e with an interpolated age of 125 ka which was globally 6 8 m higher than present sea level with characteristic warm wet tropical climatic conditions a bed composed of marine molluscs and foraminifera shells with ooids and pellets below the loamy calcareous and evaporites of the el dekheilla depression was also examined this bed is located 1 4 m b s l with an average 18o of 0 25 it is related to aminozone c isotope substage 5c 5a with an interpolated age of 110 ka and related to a transgressive sea with a mean sea level possibly equal to or slightly lower than the present one with evidence for less warm climatic conditions

glaciomorphological map of the russian federation abstract this is an overview of glacial features of the russian federation from the western border to the laptev sea in the form of an explanatory note to the map of ice marginal formations and ice limits 600 to 11 ka old attached is a generalized version of glaciomorphological map of the russian federation scale 1 2 500 000 compiled by geological research institute russian geological survey the principal purpose of the mapping is correlation of ice advances in different regions of glaciated russia possible paleogeographic and stratigraphic implications of the map pattern are discussed

comment on sea level and climate changes during ois 5e in the western mediterranean by t bardaji j l goy j l c zazo c hillaire marcel c j dabrio a cabero b ghaleb p g silva j lario geomorphology 104 2009 22 37

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

late quaternary beach deposits and archaeological relicts on the coasts of cyprus and the possible implications of sea level changes and tectonics on the early populations

seismic stratigraphy of the gulf of cadiz continental shelf a model for late quaternary very high resolution sequence stratigraphy and response to sea level fall

eastern mediterranean sea levels through the last interglacial from a coastal marine sequence in northern israel a last interglacial marine isotope stage mis5e marine coastal sequence has been identified along the galilee coast of israel with the type section located at rosh hanikra rh the microtidal regime and tectonic stability along with the detailed stratigraphy of the rh shore make the study region ideally suited for determining relative sea level rsl through the mis5e interval in the eastern mediterranean the sequence contains fossilized microtidal subunits at a few meters above the current sea level unfortunately all fossils were found to be altered so that u th datings cannot be considered to represent initial deposition we contend that u th dating of strombus bubonius shells recrystallized to calcite suffices to indicate a lower limit of 110 8 ka for the time sea level dropped below the rh sedimentary sequence the rh section comprises three main subunits of a previously determined member the yasaf member a a gravelly unit containing the diagnostic gastropod strombus bubonius lamarck persististrombus latus which was deposited in the intertidal to super tidal stormy zone b vermetidae reef domes indicating a shallow water depositional environment and c coarse to medium sized bioclastic sandstone probably deposited in the shallow sub tidal zone the sequence overlies three abrasion platforms that are cut by tidal channels at elevations of 0 8 m 2 6 m and 3 4 m and which are filled with mis5e sediments we present a detailed study of the sequence with emphasis on stratigraphic sedimentological and palaeontological characteristics that indicate sea level changes although without precise absolute dating the stratigraphic sequence of rh through mis5e allows us to identify a time series of rsl positions using the elevations of three stratigraphic subunits reconstructed rsl values range from 1 0 m to 7 m with uncertainly 1 m and most fall within a narrow range of 1 0 to 3 3 m toward the end of mis5e rsl exceeded about 7 m glacial isostatic adjustment gia modelling using multiple ice histories suggests that gia corrections range between about 1 8 m and 5 4 m this implies that global mean sea level resided between 0 8 m and 8 7 m during most of mis5e the absolute gia correction would not be constant through the interglacial and reduces to a range of 1 2 m to 2 4 m towards the end of the interglacial

flandrian sea level changes in the fenland i the geographical setting and evidence of relative sea level changes the flandrian sediments of the fenland record the infilling of the wash embayment on the east coast of england uk since at least 6500 bp changes in sea level have been a major control on the rate and pattern of sediment accumulation new data are presented from the area which together with published information allow the reconstruction of palaeoenvironments from 6500 to 2500 bp the major environmental changes involved alternations between freshwater fen and intertidal marine sedimentation each episode was characterised by transitional changes as vegetation and sediment zones shifted over large areas marine brackish sediments are found up to 45 km inland of the present coast radiocarbon dated sea level index points with relevant stratigraphic and micropalaeontological data ranging from 6415 bp at 8 17m od to 2595 bp at 1 45m od are described

effect of advective flow in fractures and matrix diffusion on natural gas production although hydraulic fracturing has been used for natural gas production for the past couple of decades there are significant uncertainties about the underlying mechanisms behind the production curves that are seen in the field a discrete fracture network based reservoir scale work flow is used to identify the relative effect of flow of gas in fractures and matrix diffusion on the production curve with realistic three dimensional representations of fracture network geometry and aperture variability simulated production decline curves qualitatively resemble observed production decline curves the high initial peak of the production curve is controlled by advective fracture flow of free gas within the network and is sensitive to the fracture aperture variability matrix diffusion does not significantly affect the production decline curve in the first few years but contributes to production after approximately 10 years these results suggest that the initial flushing of gas filled background fractures combined with highly heterogeneous flow paths to the production well are sufficient to explain observed initial production decline lastly these results also suggest that matrix diffusion may support reduced production over longer time frames

reconstructing holocene sea level change from coastal freshwater peat a combined empirical and model based approach this paper presents a novel method to reconstruct sea level change in coastal freshwater back barrier marshes freshwater environments have long been considered to be unsuitable for the reconstruction of holocene sea level changes as they provide limiting rather than precise sea level index points we recorded the stratigraphy of a small beach and back barrier coastal phragmites reed marsh at hallsands south devon southwest england using hand drilled cores and ground penetrating radar and collected five new sea level index points from the base of a holocene peat sequence to refine the regional holocene relative sea level curve we demonstrate that the samples despite their freshwater origin yield accurate sea level index points as determined from the quantifiable relationship between tide levels and groundwater by means of water table monitoring and groundwater modelling we show that the primary controls on the water table in the marsh are 1 stratigraphy 2 peat permeability and 3 recharge rates in the back barrier marsh the five index points document relative sea level positions between 7200 and 2400 cal yr bp three points are in good agreement with previously collected regional data from inter tidal deposits and two points usefully fill gaps in the existing reconstruction an amended holocene relative sea level curve for south devon based on 30 data points is presented we conclude that the combined approach of data collection and modelling used in this paper can be applied to similar coastal settings around the world and allows the collection of sea level index points from locations not previously thought suitable for this purpose

physical and biogenic aspects of backbarrier sedimentary sequences georgia coast u s a abstract configuration of the present georgia coast with its broad expanses of salt marsh and intricate tidal drainages behind pleistocene holocene barrier islands implies the filling of an extensive backbarrier lagoonal system however riverine and salt marsh estuaries dominate the modern depositional setting and reconstructed vertical sequences suggest that backbarrier filling was accomplished by estuarine processes backbarrier sediments exhibit considerable diversity in grain size and physical and biogenic sedimentary structures principal sediment textures include clean to muddy coarse and fine sand mud and to a lesser extent shells pebbles and mud and bedrock clasts physical sedimentary structures many modified by bioturbation include large scale cross bedding trough and planar with graded sets small scale crossbedding ripple lamination and flaser wavy and lenticular bedding laminated to interbedded sand and mud and rare pebble or shell beds ebb oriented structures predominate over flood oriented ones except in upper reaches of riverine estuaries biogenic sedimentary structures typically are diverse and abundant characteristic lebensspuren include polychaete dwelling tubes decapod and polychaete burrows ray holes and bioturbate textures imparted by amphipods ophiuroids bivalves and anemones patterns of bioturbation are controlled to some extent by sediment type salinity levels and rates of deposition and physical reworking of sediments although intensity of bioturbation generally increases seaward bioturbate textures are more readily preservable in the lower energy middle reaches of estuaries because of numerous local pleistocene sediment sources and local variations in hydrographic regimes the stratigraphic record of salt marsh estuaries differs relatively little from that of riverine estuaries the basic sequence in ascending order typically consists of 1 channel lag and or channel fill deposits 2 estuarine accretionary beds 3 point bar tidal flat and shoal sediments and 4 channel margin and salt marsh deposits

comment on the age of late pleistocene shorelines and tectonic activity of taranto area southern italy by g bellouomini m caldara c casini m cerasoli l manfra g mastrronuzzi g palmentola p sanso p tuccimei and p l vesica 6quaternary science reviews 21 525 5479 1

highstands during marine isotope stage 5 evidence from the ironshore formation of grand cayman british west indies abstract the ironshore formation on grand cayman is formed of six unconformity bounded packages units a f units a b c and d known from the subsurface in the northeastern part of grand cayman formed during marine isotope stages mis 11 9 7 and 5e respectively unconformities at the tops of units a b and c are highlighted by terra rossa and or calcrete layers strata in core obtained from wells drilled in george town harbour and exposed on the west part of grand cayman belong to unit d and the newly defined units e and f corals from unit e yielded th u ages of 104 ka whereas conch shells from unit f gave ages of 84 ka unit e equates to mis 5c whereas unit f developed during mis 5a th u dating of corals and conchs from the ironshore formation on the western part of grand cayman shows that unit d formed during the mis 5e highstand whereas units e and f developed in association with highstands at 95 110 ka mis 5c and 73 87 ka mis 5a unit e 5 m thick in the offshore cores is poorly represented in onshore exposures unit f which unconformably overlies unit d at most localities is formed largely of fossil poor cross bedded ooid grainstones the unconformity at the top of unit d a marine erosional surface with up to 2 5 m relief is not characterized by terra rossa or calcrete in the offshore cores or onshore exposures unit d formed with a highstand of 6 m asl whereas units e and f developed when sea level was 2 to 5 asl and 3 to 6 m asl respectively thus the highstands associated with mis 5e 5c and 5a were at similar elevations

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

uranium series dating of quaternary deposits abstract this is a review of u series dating methods as applicable to terrestrial sedimentary materials alpha counting techniques allow the dating of carbonates and phosphates with a precision of 5 to 10 over the time range from 1 ka to 350 ka atom counting methods mass spectrometry and ams substantially increase precision and may increase the range problems of contamination and open system behavior are discussed correction for detrital contaminant is demonstrated in the dating of speleothem from a cave in italy

uranium series ages of fossil corals from mallorca spain the neotyrrhenian high stand of the mediterranean sea revisited abstract the emergent marine deposits of the mediterranean basin have been recognized as an important record of quaternary sea level history for more than a century previous workers identified what have been interpreted to be two separate high stands of sea in the late quaternary namely the eutyrrhenian thought to be 120 ka and the neotyrrhenian thought to be either 100 ka or 80 ka on mallorca spain both of these named deposits lie close to present sea level implying paleo sea levels slightly above present during both marine isotope stages mis 5 5 5e and either 5 3 5c or 5 1 5a if these interpretations are correct they conflict at least in part with sea level records from far field localities we analyzed corals from the neotyrrhenian beds on mallorca which gave u series ages from 126 ka to 118 ka these ages are consistent with previously published amino acid data that show that the neotyrrhenian and eutyrrhenian deposits are not significantly different in age a fossil molluscan fauna from the neotyrrhenian deposits on mallorca has a warm water paleozoogeographic aspect with nine southward ranging species and four extralimital southern species when compared with sea surface temperatures obtained from planktonic foraminifera and alkenones from odp core 977 in the nearby alboran sea the only time period that shows comparable warmth is mis 5 5 5e consistent with the u series ages of corals from the neotyrrhenian deposits we propose that the neotyrrhenian deposits are a beachrock facies of the same age as the eutyrrhenian deposits this interpretation is consistent with the differences in physical sedimentology of the two deposits explains the u series and amino acid data indicating the same age is consistent with the very slight elevation difference of the neotyrrhenian and eutyrrhenian beds and explains the similar though not identical paleozoogeographic aspects of their fossil faunas

on the postglacial isostatic adjustment of the british isles and the shallow viscoelastic structure of the earth summary observations of postglacial relative sea level rsl history at sites beyond the margins of the main accumulations of wu rm wisconsin devensian ice may be invoked to test the accuracy of global models of the glacial isostatic adjustment process the existing database of rsl time series for the british isles forms a continuous network of sites that sample the coasts of scotland england and wales fairly uniformly and which may be especially important in this regard not only are these 14c data for the holocene epoch of very high quality in terms of our knowledge of the coastal environment and relationship to palaeo sea level of each age measurement but they are especially numerous and relate to an island that was itself partly glaciated in the north essentially ice free in the south and located well outboard of the massive ice sheet that covered fennoscandia at the last glacial maximum lgm taken together the time series from 55 distinct locations allow us to perform a fairly stringent test of the recently formulated ice 4g vm2 global model of the isostatic adjustment process even without modification this model has been shown to fit most of the time series in the uk data set rather well in order to satisfy very recently published a priori constraints on the maximum thickness of the scottish ice sheet however we find that the lithospheric thickness the feature of the radial viscoelastic structure to which the rebound data from scotland are most sensitive must be somewhat reduced whereas the assumed thickness of the lithosphere in ice 4g vm2 was near to 120 km best fits to the scottish data require a lithospheric thickness near to 90 km this reduced value for lithospheric thickness agrees exceedingly well with the latest estimates of this earth property based on the inversion of oceanic geoid and topography data as the asymptotic thickness characteristic of the oldest ocean floor this would appear to be the best possible a priori estimate for the thickness of the cratonic lithospheres upon which the largest ice sheets of the late pleistocene are known to have rested we also demonstrate explicitly that inferences of the shallow viscoelastic structure beneath the british isles are strongly influenced by the details of the history of deglaciation at remote locations at antarctica in particular

quaternary development and evolution of the sedimentary environments in the central mediterranean spanish coast abstract the reconstruction of the evolutive phases of the mediterranean spanish central sector during the late quaternary is the aim of this work from geomorphological sedimentological and chronometrical studies different morphostratigraphic units are determined results point out the development of several transgressive phases the older one go back to isotope stage 7 the eemian transgression is broadly recorded and its coastline was near the present one during the flandrian episode the sea surpassed the current coastline in the northern coastal plain while in the meridional littoral erosive notches were formed between 1 and 2 m during the regressive events we find the progradation of the continental sediments with alluvial and colluvial facies we note the terminal phases of the wurmiam glaciation because of their marked climatic aridic characteristics

land sea correlation of middle pleistocene temperate sub stages using high precision uranium series dating of tufa deposits from southern england abstract high precision u series dating allows a direct correlation to be made between terrestrial records of the penultimate interglacial marine oxygen isotope stage 7 mis 7 in britain and sub stage climate forcing in the marine oxygen isotope sequence u series ages of surficial tufa deposits are of sufficient precision to correlate discrete episodes of temperate conditions with individual warm sub stages within mis 7 furthermore detailed biostratigraphy allows periods of faunal turnover to be correlated with cold climates and lowered sea level ecological and environmental conditions in britain during mis 7 are therefore driven by the short lived sub stage climate forcing that is observable in the marine isotope record it is clear that interglacial climates are highly dynamic producing multiple climatic optima and a diverse range of environments within single warm episodes consequently sub stage records of climate forcing are crucial frameworks for reconstructing terrestrial records of environmental change

postglacial relative sea level observations from ireland and their role in glacial rebound modelling the british isles have been the focus of a number of recent modelling studies owing to the existence of a high quality sea level dataset for this region and the suitability of these data for constraining shallow earth viscosity structure local to regional ice sheet histories and the magnitude timing of global meltwater signals until recently the paucity of both glaciological and relative sea level rsl data from ireland has meant that the majority of these glacial isostatic adjustment gia modelling studies of the british isles region have tended to concentrate on reconstructing ice cover over britain however the recent development of a sea level database for ireland along with emergence of new glaciological data on the spatial extent thickness and deglacial chronology of the irish ice sheet means it is now possible to revisit this region of the british isles here we employ these new data to constrain the evolution of the irish ice sheet we find that in order to reconcile differences between model predictions and rsl evidence a thick spatially extensive ice sheet of 600 700 m over much of north and central ireland is required at the lgm with very rapid deglaciation after 21 k cal yr bp copyright 2007 john wiley sons ltd

a new holocene relative sea level curve for western brittany france insights on isostatic dynamics along the atlantic coasts of north western europe abstract this study presents new relative sea level rsl data that were obtained in the finistere region western tip of brittany france and the implications those data have for the understanding of the isostatic dynamics across north western europe and more specifically along the atlantic and channel coasts new stratigraphic sequences were obtained and analyzed to derive 24 new sea level index points in which 6 are basal these new data considerably increase the knowledge we have of the rsl evolution along the coasts of western brittany since the last 8 kyr b p from this new dataset rsl was estimated to rise continuously over the last 8 kyr with a major inflection at ca 6 kyr cal bp our results show large vertical discrepancies between the rsl records of brittany and south western uk with the latter plotting several meters below the new data from this comparison we suggest that the two regions underwent a very different pattern and or amplitude of subsidence during the last 8 kyr which has implications for the spatial and temporal pattern of the peripheral bulge of the european ice sheets we compared our data against predictions from glacio isostatic adjustment models gia models there are large misfits between rsl observations and the predictions of the global ice 5g vm2a peltier 2004 glac1 b tarasov and peltier 2002 tarasov et al 2012 briggs et al 2014 and regional uk models biis bradley et al 2009 bradley et al 2011 kuchar kuchar et al 2012 which can t be resolved through significant changes to the deglaciation history and size of the british irish ice sheet paleo tidal modelling corrections indicate regional changes in the tidal ranges played a negligible role in the data model misfits hence we propose that the misfits are due to some combination of i unaccounted mass loss of far field ice sheets antarctic ice sheet or laurentide ice sheet ii unresolved differences in the deglaciation history and size of the fennoscandian ice sheet or more likely iii significant lateral variations in the earth s structure across the english channel

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

influence of fracture scale heterogeneity on the flow properties of three dimensional discrete fracture networks dfn while permeability scaling of fractured media has been so far studied independently at the fracture and network scales we propose a numerical analysis of the combined effect of fracture scale heterogeneities and the network scale topology the analysis is based on 2 106 discrete fracture network dfns simulations performed with highly robust numerical methods fracture local apertures are distributed according to a truncated gaussian law and exhibit self affine spatial correlations up to a cutoff scale lc network structures range widely over sparse and dense systems of short long or widely distributed fracture sizes and display a large variety of fracture interconnections flow bottlenecks and dead ends at the fracture scale accounting for aperture heterogeneities leads to a reduction of the equivalent fracture transmissivity of up to a factor of 6 as compared to the parallel plate of identical mean aperture at the network scale a significant coupling is observed in most cases between flow heterogeneities at the fracture and at the network scale the upscaling from the fracture to the network scale modifies the impact of fracture roughness on the measured permeability this change can be quantified by the measure a2 which is analogous to the more classical power averaging exponent used with heterogeneous porous media and whose magnitude results from the competition of two effects i the permeability is enhanced by the highly transmissive zones within the fractures that can bridge fracture intersections within a fracture plane ii it is reduced by the closed and low transmissive areas that break up connectivity and flow paths citation de dreuzy j r y meheust and g pichot 2012 influence of fracture scale heterogeneity

identification of a holocene aquifer lagoon system using hydrogeochemical data abstract the hydrogeochemical characteristics of the cabo de gata coastal aquifer southeastern spain were studied in an attempt to explain the anomalous salinity of its groundwater this detritic aquifer is characterised by the presence of waters with highly contrasting salinities in some cases the salinity exceeds that of seawater multivariate analysis of water samples indicates two groups of water g1 and g2 group g1 is represented in the upper part of the aquifer where the proportion of seawater varies between 10 and 60 whilst g2 waters taken from the lower part of the aquifer contain 60 70 seawater in addition hydrogeochemical modelling was applied which reveals that the waters have been subject to evaporation between 25 and 35 there was a good agreement between the modelled results and the observed water chemistry this evaporation would have occurred during the holocene in a coastal lagoon environment the resulting brines would have infiltrated into the aquifer and due to their greater density sunk towards the impermeable base the characteristics of this water enabled us to reconstruct the interactions that must have occurred between the coastal aquifer and the lagoon and to identify the environmental conditions that prevailed in the study area during the middle holocene

transport behavior in three dimensional fracture intersections 1 flow and transport patterns in three dimensional fracture intersections are investigated with emphasis on the occurrence and effects of local flows around each intersection flow and transport simulations indicate that local flow circulations referred to as local flow cells arise because of an interplay between intersection geometry and corresponding boundary conditions for flow along the fracture boundaries local flow cells are thus unique features in three dimensional fracture networks the analysis here suggests that local flow cells have little effect on the overall fluid flow in a fracture network but may constitute an effective mechanism which contributes to the long breakthrough tailing and retardation often observed in transport through discrete fracture networks

stochastic simulation of radionuclide migration in discretely fractured rock near the aspo hard rock laboratory we study the migration of sorbing tracers through crystalline rock by combining relatively simple transport measures with particle tracking in a discrete fracture network the rock volume is on a 1

holocene land and sea level changes in great britain analysis of more than 1200 radiocarbon dated samples that constrain relative sea levels in great britain over the past 16 000 yr provides estimates of current land level changes negative of relative sea level change maximum relative land uplift occurs in central and western scotland ca 1 6 mm yr 1 and maximum subsidence is in southwest england ca 1 2 mm yr 1 sediment consolidation arising from autocompaction as the sediment accumulates and from land drainage increases the subsidence in areas with thick sequences of holocene sediments with an average effect equivalent to at least an extra ca 0 2 mm yr 1 land subsidence but more in parts of southeast england 0 5 1 1 mm yr 1 modelled changes in tidal range during the mid to late holocene in eastern england suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified the effect is most significant for large coastal lowlands the fenland and humber ca 0 5 and 0 6 mm yr 1 that were tidal embayments during the mid to late holocene

holocene relative sea level changes in the inner solway firth abstract bio and lithostratigraphic data from four sites from the inner solway firth allow an accurate reconstruction of holocene rsl changes in the estuary radiocarbon assays give eleven new sea level index points providing a total of 24 reliable index points for the inner solway firth these data show a consistent pattern of rapid rsl rise during the early holocene culminating in a mid holocene sea level maximum then a gradual fall to the present day level detailed analysis of this dataset quantifies for the first time differential crustal movement between the north and south shores of the solway firth these data are used to test the accuracy of quantitative isostatic rebound models of lambeck and peltier and show there is good general agreement between the data and the models especially during the early holocene the models predict the mid holocene sea level peak slightly later than shown by the data c 500 and c 2000 yr this may be partly due to lack of resolution in the models and for the south solway the maximum altitude at this peak is 1 and 2 5 m too high in the two models the data are also compared to the isobase models of the main postglacial shoreline showing slight diachroneity between the north and south shore but otherwise general agreement with the postulated age and indicating that the altitude of this feature is 1 3 m higher than suggested by the models

last interglacial coastal environments in the mediterranean saharan transition zone abstract the coast of tunisia stretches from the western mediterranean climate belt in the north to the saharan desert climate belt in the south the sediments of this coastal strip provide a record of sea level change if an accurate chronology of the coastal deposits is available we have here surveyed and analysed coastal sites and established a chronology based on optical dating techniques the optical ages range from 156 ka to 62 ka 2 level and cluster around the last interglacial period 125 75 ka our study shows that sea level rose after termination ii for about 25 ka leading to a transgressive deposit at 120 ka a disconformity shown by some deposits suggests a brief drop of sea level during this transgressional phase subsequently for around 40 ka the coastal area became covered by soils colluvia and aeolian sediments indicating a slowly falling sea level while the composition of sediments at the north coast did not change the deposits at the central and south coast experienced a drastic change from a quartz to a carbonate dominated sedimentation sometime during the last interglacial littoral sedimentation ceased at 70 ka when the coast became sediment starved in the course of the falling sea level

the lithostratigraphy and biostratigraphy of a holocene coastal sediment sequence in marazion marsh west cornwall u k with reference to relative sea level movements abstract a holocene sedimentary sequence at marazion marsh mount s bay west cornwall u k is examined with reference to coastal evolution and relative sea level change a sample core analyzed in this paper shows the base of the sedimentary sequence rests on weathered bedrock material basal organic rich deposits are overlain by minerogenic materials dominated by sand a sharp contact separates these two sedimentary units changing coastal conditions are reconstructed using lithostratigraphic biostratigraphic and chronometric data from this sequence the lower organic rich unit accumulated between ca 5420 60 and 4380 55 yrs b p substantial changes in the marsh environment involving vegetation succession from initial herb domination to mesophytic woodland and eventually to fen carr reed marsh development is indicated by pollen records from this unit diatom data show increased salinity within the basal sequence as arboreal pollen values decline and fen carr reed marsh becomes established radiocarbon dates from this and other cores from west cornwall are used to construct a local time altitude plot of relative sea level rsl it is concluded that the sediment sequence at marazion marsh appears to have accumulated in an embayed environment the sequence was both indirectly and directly affected by changes in relative sea level position and the influence of protective transgressive coastal morpho sedimentary structures and associated processes of sedimentation during the mid holocene period

vegetation history of the marine isotope stage 7 interglacial complex at ioannina nw greece abstract a new pollen record of the penultimate interglacial complex corresponding approximately to marine isotope stage mis 7 ca 186 000 245 000 years before present has been generated in core i 284 from the ioannina basin in northwest greece it represents the highest resolution terrestrial record for this interval available to date with a mean sampling interval of 200 years the sequence records four forested intervals correlated with mis 7e 7c 7a and a sub orbital scale event following 7a but within mis 7 the longest and most complete warm stage in terms of vegetational succession is mis 7c while the succession in mis 7e appears to be truncated by a shift to colder drier climatic conditions the results of biomisation suggest that during all of these intervals winter temperatures in nw greece remained lower than during the eemian or holocene while smaller populations of sclerophyllous taxa indicate that summers may have been wetter intervening intervals of open vegetation are correlated with mis 7d 7b and an oscillation following 7a low tree pollen percentages during mis 7d are interpreted as reflecting very cold and dry conditions concomitant with a period of low northern hemisphere insolation which resulted from a rare combination of minimum obliquity and maximum precession higher tree pollen percentages throughout mis 7b by contrast are indicative of relatively mild conditions in agreement with marine temperature and ice volume records sub orbital scale oscillations in tree population extent are also recorded in the new i 284 record suggesting that just as in the last climatic cycle nw greece was affected by rapid climatic oscillations that are associated with changes in the north atlantic