climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

assessing the reliability of magnesium in foraminiferal calcite as a proxy for water mass temperatures though many studies on the mg contents in the calcitic tests of foraminifers exist the processes controlling its uptake are still a matter of debate laboratory cultures offer an excellent opportunity to reveal these mechanisms the mg concentrations within single chambers of the planktic foraminifer globigerinoides sacculifer brady maintained under controlled laboratory conditions were measured 1 at variable temperatures 19 5 29 5 c and constant salinity and 2 at variable salinity 22 45 and constant temperature the experimental results suggest that under natural conditions temperature is the leading mechanism controlling the mg ca ratio temperature and magnesium are related proportionally a temperature increase of ca 10 c gives rise to an increase of the magnesium concentrations of ca 130 drastic unnatural salinity changes dominate the effects of temperature a 110 change in the mg ca ratio was observed when salinity was elevated or reduced by more than ca 10 specimens which underwent gametogenesis reveal significantly higher mg concentrations than specimens that did not release gametes partition coefficients for mg in foraminiferal calcite are orders of magnitude lower than values from inorganically precipitated calcite when comparing observed mg ca ratios of foraminiferal tests with predicted mg ca ratios calculated according to empirical equations it becomes evident that foraminiferal tests are undersaturated with respect to mg for the water temperature they have experienced apparently foraminifers are capable of controlling their mg concentration the physiological processes presumably responsible for such depressed mg ca ratios appear to be temperature controlled as deduced from the close relationship of the observed mg ca ratios and water temperature this study demonstrates that variations in temperature and salinity are definitely reflected in the mg content of foraminiferal tests magnesium may thus serve as a paleo proxy for past surface water temperatures as long as postdepositional changes and salinity variations are of subordinate importance or can be excluded

stress tensor determination from the study of e twins in calcite a linear programming method abstract a new method for the determination of the stress tensor from calcite e twin lamellae has been discovered all e planes twinned and untwinned are taken into account to enable derivation of tensor characteristics the basic assumption is that the resolved shear stress a linear function of the unknown stress tensor components is greater respectively lower than the critical resolved shear stress for the twinned respectively untwinned planes the relevant inequality constraints can be solved using linear programming algorithms the application to experimental carrara marble and natural samples a goniatite from morocco has come up against one major difficulty polyphase deformation thus before applying this method it is necessary to operate some selection of the data one procedure based upon linear programming is proposed the results are consistent with those expected both for the experimental and natural cases for the carrara marble an estimate of the critical resolved shear stress t c for twinning gave a value around 300 400 bar the method can give in principle the stress tensor orientation and the relative magnitude of principal stresses simultaneously

surface and subsurface seawater temperature reconstruction using mg ca microanalysis of planktonic foraminifera globigerinoides ruber globigerinoides sacculifer and pulleniatina obliquiloculata laser ablation inductively coupled plasma mass spectrometry microanalyses of mg ca across individual final chambers of three planktonic foraminifera species globigerinoides ruber g sacculifer and pulleniatina obliquiloculata reveal significant interspecies differences in test mg concentrations whereas these three species have similar mg ca values at low sea surface temperatures similar to 22 degrees c they diverge markedly at high sea surface temperatures similar to 29 degrees c explanations for these differences in species mg ca values based on detailed comparison of species intratest mg ca distributions suggest that compositional variability within tests cannot account for the observed deviation of species mg ca values in warm water equatorial regions multiple regression modeling and delta o 18 analysis of globigerinoides sacculifer tests indicate that interspecies differences in mg ca values result from different depth habitats the average mg ca values of g ruber final chambers reflect the temperature of the surface mixed layer 0 25 m whereas those of g sacculifer and pulleniatina obliquiloculata correlate best with subsurface temperatures at 50 75 m and 100 125 m water depths respectively mg ca calibration to the temperatures at these depths reveals a similar temperature control on mg test composition in all species combining our results with mg ca values from published culturing experiments we derive a generalized equation for the effect of temperature and seawater salinity on foraminiferal mg ca we also show that the mg ca composition of specific calcite layers within foraminiferal tests including the low mg ca layers of globigerinoides ruber and g sacculifer and the cortex layer of pulleniatina obliquiloculata correlates with seawater temperature and can be used as an additional proxy for seawater temperature

a study of cleaning procedures used for foraminiferal mg ca paleothermometry the various cleaning steps required for preparation of foraminiferal samples for mg ca and sr ca analysis are evaluated for their relative importance and effects on measured elemental ratios it is shown that the removal of silicate contamination is the most important step for the measurement of mg ca ratios in an example bulk sample mg ca decreases from 10 5 to 2 5 mmol mol 1 during clay removal oxidation of organic material causes a lowering of sample mg ca in the order of 10 or approximately 1 c when converted to temperature use of dilute acid leaching to remove adsorbed contaminants causes partial dissolution of the sample carbonate and a corresponding decrease in mg ca reductive treatment also causes dissolution of the sample and a decrease in the mg ca ratio of up to 10 15 sample preparation for sr ca analysis does not require the same degree of rigor as is necessary for mg ca work the within run reproducibility of the method described here for g ruber in a core top sample from the arabian sea was 1 8 mean sample ratio was 4 72 mmol mol 1 when converted to temperature this becomes 28 0 2 c the equivalent result for sr ca was 0 5 mean ratio 1 44 mmol mol 1

pleistocene chronostratigraphy in estonia southeastern sector of the scandinavian glaciation abstract pleistocene chronostratigraphy in estonia is based on 29 studied sites sections the dating of which covers a span from approximately 200 ka bp to the pleistocene holocene chronostratigraphic boundary and a local varved clay chronology for eastern estonia which enables tentative correlation of lateglacial lg events to finnish and swedish varve chronologies analysis of existing and unpublished data was used to review the current pleistocene chronostratigraphy and particularly the history of weichselian cold stage in estonia osl ages from fluvial deposits that included the korvekula holsteinian or rongu eemian continental interglacial deposits revealed that the pre weichselian interglacial deposits were glacially dislocated during the weichselian available osl tl and 14 c dates and new 14 c ams ages of mammoth bones indicate ice free conditions between 105 and 68 ka bp and a comparatively mild middle weichselian between 43 and 22 ka bp the lg chronology indicates in general rapid average 110 m yr deglaciation of the territory between ca 14 7 and 12 7 ka bp the duration of the late weichselian glaciation in estonia ranged between 7 3 and 9 3 ka

eemian and early weichselian environments in southern sweden a multi proxy study of till covered organic deposits from the smaland peneplain based on their luminescence and infinite radiocarbon ages organic deposits beneath till at two sites on the smaland peneplain southern sweden nybygget and stora gaddevik are concluded to have formed before the middle weichselian applied palaeoecological methods include analyses of pollen diatoms charcoal fragments macroscopic remains of vascular plants and mosses and insect remains pollen stratigraphical correlations with previously studied interglacial interstadial sites in southern sweden denmark and northern germany suggest that the peat at nybygget dates from the brorup interstadial or the final stage of the eemian interglacial whereas the lake sediments at stora gaddevik probably were emplaced during the middle eemian we conclude that the peat was formed in a wetland characterized by both wood swamp and open mire vegetation and surrounded by semi open woodlands dominated by pine birch and hazel the middle eemian sequence at the stora gaddevik site provides evidence of a moderately nutrient rich to nutrient rich lake environment with relatively diverse aquatic vegetation regional vegetation as reconstructed using the reveals model was spruce woodland mixed with pine alder and birch but also included more open environments with hazel oak grasslands and sedge dominated wetlands water shield brasenia schreberi now extinct in europe was identified in the eemian lake deposits from both pollen and macroscopic remains

the last interglacial glacial cycle in ne fennoscandia a nearly continuous record from sokli finnish lapland abstract boreholes from the sokli basin in finnish lapland have recovered a unique sequence of diamicts interlayered with fine grained sediments that are rich in fossils the diamicts are interpreted as till beds deposited by the fennoscandian ice sheet the fine grained intercalations seem to represent a series of warm stages that include one interglacial and three interstadials the interglacial is characterized by a mixed taiga pollen assemblage and corresponds to a distinct diatom gyttja bed the interstadials show progressively colder floras from open birch forest to arctic forest limit to shrub tundra their sediments comprise gyttja interlayered with wood and sand interstadial 1 sands grading into sandy gyttja interstadial 2 and sands overlain by laminated silt and clay interstadial 3 the interstadial 2 and 3 deposits are underlain by diamict and are interpreted as deglaciation sequences silts with a tundra pollen assemblage separate the interglacial and interstadial 1 deposits luminescence dating evidence indicates that the interglacial bed most probably represents the nw european mainland eemian interglacial marine isotope stage mis 5e the interstadial 1 2 and 3 deposits are tentatively correlated with the early weichselian brorup and odderade interstadials and an interstadial of middle weichselian age respectively mis 5c 5a and 3 respectively the correlation implies that the easternmost part of the ice divide zone of the fennoscandian continental ice sheet was deglaciated during part of mis 3

present day temperatures in northern scandinavia during the last glaciation scandinavia is generally considered to have been covered extensively with ice throughout marine isotope stages mis 4 2 between 75 and 10 ka here we present evidence for ice free warm conditions in the central area of the scandinavian glaciations during mis 3 our multiproxy data obtained from a lacustrine sequence in northern fin land reveal not only significant response in the northeastern sector of the scandinavian ice sheet to warming during the early part of mis 3 but also indicate rapid climate warming to present day temperatures in this ice free period new climate model simulations for interstadial conditions in mis 3 confirm the high mean july temperatures northeast of the scandinavian ice sheet in response to the high insolation values and the presence of the ice sheet during mis 3

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

southwest scandinavia 40 15 kyr bp palaeogeography and environmental change twelve palaeogeographical reconstructions illustrate environmental changes at the southwest rim of the scandinavian ice sheet 40 15 kyr bp synchronised land sea and glacier configurations are based on the lithostratigraphy of tills and intertill sediments dating is provided by optically stimulated luminescence and calibrated accelerator mass spectrometry radiocarbon an interstadial sequence ca 40 30 kyr bp with boreo arctic proglacial fjords and subarctic flora and occasional glaciation in the baltic was succeeded by a last glacial maximum sequence ca 3020 kyr bp with the closure of fjords and subsequent ice streams in glacial lake basins in kattegat and the baltic steadily flowing ice from sweden bordered the norwegian channel ice stream a deglaciation sequence ca 20 15 kyr bp indicates the transgression of arctic waters retreat of the swedish ice and advance of baltic ice streams succeeded by a return to interstadial conditions when ameliorated ice free conditions prevailed in maritime regions glaciers advanced through the baltic and when interstadial regimes dominated the baltic glaciers expanded off the norwegian coast the largest glacier extent was reached in the north sea around 29 kyr bp about 22 kyr bp in denmark and ca 18 kyr bp in the baltic our model provides new data for future numerical and qualitative landform based models copyright c 2003 john wiley sons ltd less

a late pleistocene marine clay succession at kriegers flak westernmost baltic southern scandinavia in the baltic sea south of skane county in southern sweden an over consolidated marine clay succession on the northeastern slope of kriegers flak was observed in shallow seismic data as a unit overlain by younger weichselian sediments two cores were taken from the clay succession the foraminifera present were predominantly of two species elphidium excavatum and elphidium albiumbilicatum reflecting deposition under arctic boreal conditions stable oxygen isotope analyses were performed on foraminiferal tests and the results show extremely light 18o values ranging between 11 and 12 the cause of these extreme values is uncertain but may result from the high influence of meltwater brackish conditions are also indicated by the tolerance for low salinity shown by the foraminifera radiocarbon dating shows an infinite age 40000 yr bp the pollen flora seems mainly to have been redeposited which makes interpretation difficult the sea may have entered the baltic basin during periods with high eustatic levels an isostatic downloading of the crust or a combination of both it is suggested that the deposition of the overconsolidated marine clay succession occurred in the late saalian early eemian or early weichselian 1998 john wiley sons ltd

analysis of a gradual change in stress regime example from the eastern iberian chain spain abstract the compression extension passage in the eastern iberian chain during the miocene is analyzed structural data suggest that it is a gradual change in stress regime which does not involve rotation but interchange of 1 and 2 axes one of them remaining always vertical the gradual stress evolution is interpreted by a numerical graphic method y r diagram which optimizes combinations of y azimuth of the maximum horizontal axis and r stress ratio explaining groups of fault movements the y r diagrams of some fault populations measured in the castellon region provide optimum tensors appearing within a continuous cloud of solutions from the compressional field to the extensional one movement sequences obtained from superimposed striations indicate a systematic stress change between these two regimes

a middle weichselian interstadial lake deposit on sejero denmark macrofossil studies and dating studies of lake sediments on sejero in southern kattegat indicate a treeless arctic environment with the dwarf shrub salix polaris herbs and wetland mosses the mean july temperature was around 8 to 10 c an ams radiocarbon age determination of a salix twig yielded an age of around 36 000 14c yr bp which is in accordance with previous conventional dating of bulk sediment samples copyright 2006 john wiley sons ltd

systematic change of foraminiferal mg ca ratios across a strong salinity gradient abstract the mg ca ratio of foraminiferal calcite is an important proxy for estimating past ocean temperatures used in conjunction with 18 o of foraminiferal calcite it allows deconvolution of temperature and ice volume signals to infer past ocean temperatures and salinities assuming the relationship between seawater 18 o and salinity is known such work assumes that temperature is the only or at least the dominant environmental controller of foraminiferal mg ca the semi enclosed mediterranean sea where salinity varies from 36 to 40 psu over a seasonal temperature range of between only 5 c to 8 c provides a relevant setting to test this assumption outside the laboratory in this study planktonic foraminifera o universa g siphonifera g bulloides and g ruber white and pink were picked from 11 box core tops spanning the mediterranean salinity gradient and analysed for their trace element concentrations mg ca ratios are higher for the associated calcification temperatures than in other regions where calibrations have been conducted and correlate poorly with calcification temperature mg ca ratios are particularly high for samples from the eastern mediterranean where salinity is unusually high correlations of mg ca with the calcification salinity are statistically significant with mg ca changing by 15 59 per psu suggesting that salinity may act as a control on mg ca ratios in addition to the dominant temperature control we show that contamination by non carbonate material and diagenetic high mg carbonate overgrowths cannot account for the observed trend of increasing mg ca with salinity a relationship between mg ca and salinity is also suggested by re analysis of calibrations from open ocean settings these new mediterranean results are from a region with unusually high salinity but suggest that the effects of salinity on the mg ca palaeothermometer should be considered even in open ocean settings particularly where large salinity changes occurred in the past

mis 3 mammoth remains from sweden implications for faunal history palaeoclimate and glaciation chronology the distribution of low arctic megafaunal remains in time and space from the area previously covered by the scandinavian ice sheet sis suggests the presence of breeding mammoth populations in the circum baltic region during the time interval from 44 to 26 ka ago the transport history of 30 mammoth teeth and bones from southern and north central sweden was estimated and the remains were subjected to osteological analyses and 14c dating oxygen isotope analyses of tooth enamel indicate a palaeoclimate considerably more homogenous than that experienced in sweden today showing moderate north south gradients in the d18o value of precipitation and temperature in general the results support the model of restricted ice sheet distribution during the second half of the middle weichselian the clear discrepancy in the inferred absence of glaciation in the central swedish uplands and the baltic basin as evidenced by the swedish mammoth data versus the danish osl based glaciation chronology in the period from 40 to 30 ka ago is discussed in the light of radiocarbon calibration and glacial dynamics r 2007 published by elsevier ltd less

a multi disciplinary macrofossil study of middle weichselian sediments at kobbelgard mon denmark abstract multi proxy studies of radiocarbon and luminescence dated middle weichselian sediments and allochthonous plant and animal macrofossils from kobbelgaard mon point to a lacustrine environment with shallow mesotrophic fresh water the lake was surrounded by mires rich in mosses and carex while the vegetation on the uplands was tree less and herb dominated but with scattered shrubs the climate was considerably colder than at the present day with average july temperatures around 11 c about 6 c below those for the region today probably normal for the later part of the middle weichselian the sediments contain the first remains of lemmings dicrostonyx torquatus and lemmus lemmus found in denmark

patterns of total and incremental strain in subsiding troughs experimental centrifuged models of inter diapir synclines the experimental technique of centrifuge modelling has been used to elucidate patterns of total strain and progressive deformation associated with troughs that form by gravitational subsidence of a dense cover into a less dense basement model structures are analogous to synclines found between mantled gneiss domes and the models provide data with which to test the hypothesis that archean greenstone belts are products of vertical gravity tectonics experimental results include the following 1 strain within the main body of subsiding belts is dominated by strong horizontal contraction and vertical extension in natural structures this strain pattern would produce vertical foliation and steeply plunging mineral lineation 2 within cover units near trough margins the flattening plane trends parallel with or at a low angle to the cover basement interface at all levels in the trough 3 patterns of strain within subsiding troughs at least as expressed in surface deformation reflect the geometry of the

on the fidelity of shell derived δ18oseawater estimates article i nfo 18 oseawater a robustproxyforsurfacesalinity we assessthe fidelity of shell derived 18 oseawater estimates for the surface dwelling foraminifer globigerinoides ruber white using an atlantic meridional coretop transect spanning basin scale temperature and salinity gradients shell derived and observed 18 oseawater values are well correlated r 2 0 77 but a large systematic bias is observed shell mg ca ratios are significantly elevated above values expected from observed and isotopic calcification temperatures in the saline subtropical gyres of both hemispheres this temperature independent shell mg ca ratio variability termed excess mg ca i s highly correlated with surface salinity r 2 0 77 and the observed salinity dependence 27 4 is much higher than indicated by culture studies 6 2 our coretop data are used to develop new atlantic basin temperature and salinity calibration equations that are accurate 1 1 c and 0 20 respectively precise r 2 0 82 and 0 81 respectively and verifiable using previously published data these results are valid for the relatively high salinities of the subtropical atlantic 35 5 37 3 we discover that inclusion of other published data from lower salinity regions b35 indicates little or no excess mg ca taken together these results point to a strongly non linear positive salinity effect on shell mg ca ratios that significantly affects the accuracy of sst and 18

new spatial mg ca temperature calibrations for three arctic benthic foraminifera and reconstruction of north iceland shelf temperature for the past 4000 years 1 we have developed cold end mg ca temperature calibrations for three common arctic benthic foraminifera islandiella norcrossi helenae melonis barleeanus and cassidulina neoteretis and compare the three calibrations in a late holocene downcore record 0 4000 cal yr b p the calibration and downcore trends for the three arctic species extend the observation that mg incorporation into benthic foraminifera is species specific for the calibration we use a set of ctd casts bottom water 18oseawater measurements and surface grab samples collected from the iceland margin cruise b997 and the greenland margin cruise bs1191 water depth of sites used ranges from 165 to 656 m while spatial bottom temperature ranges from 0 to 7 c mg ca values ranged from 1 02 to 1 47 for i norcrossi helenae 0 64 to 2 21 for m barleeanus and 0 93 to 1 38 mmol mol for c neoteretis we calibrated mg ca content against isotopic calcification temperature calculated using t 16 9 4 0 18ocalcite corrected for vital effect 18oseawater exponential calibrations for the three species are as follows i norcrossi helenae mg ca 1 051 0 03 exp 0 060 0 011 t m barleeanus mg ca 0 658 0 07 exp 0 137 0 020 t and c neoteretis mg ca 0 864 0 07 exp 0 082 0 020 t on the basis of mg ca in these benthic species the downcore record from core md99 2269 is reconstructed bottom temperature values are interpreted to reflect variable inflow of atlantic and arctic water to the north iceland shelf during the last 4000 cal yr b p all three reconstructions show a decline by 0 1 c per century from circa 1500 0 cal yr b p which coincides with an increase in arctic benthic foraminifera abundances and a rise in sea ice proxies in the same core intriguingly c neoteretis diverges periodically to higher average temperature atlantic water conditions than shown by m barleeanus or i norcrossi helenae which both show arctic water temperature circa 1500 4000 cal yr b p

palaeoenvironments in the southern baltic sea basin during marine isotope stage 3 a multi proxy reconstruction abstract sediment cores from kriegers flak in the southwestern baltic sea provide a unique possibility to study the middle weichselian history of the baltic basin three weichselian interstadial units have been identified and are attributed to marine isotope stage 3 mis 3 60 25 ka the oldest unit a is characterized by a deglaciation sequence gradually turning into brackish water clay the low diversity benthic foraminiferal fauna stable oxygen isotope values and mg ca ratios indicate low temperature and salinity for unit a a hiatus separates unit a from the overlying unit b which was deposited in wetlands and shallow lakes between 42 and 36 cal ka bp macrofossil and pollen analyses indicate deposition of unit b in an area dominated by a tree less open tundra environment possibly with some birch and pine in sheltered positions the uppermost unit c is characterized by clay deposition including redeposition of material from older sediments unit b optically stimulated luminescence osl ages indicate deposition of unit c between 26 and 28 5 ka radiocarbon ages of 39 and 40 cal ka bp for unit c are considered to be too old the following depositional model is suggested i isostatic depression of the region after an advance of the scandinavian ice sheet sis most likely the ristinge ice advance previously dated to c 55 50 ka enabled an inflow of marine waters into the baltic basin during the deposition of unit a ii isostatic rebound caused a regression at kriegers flak and a hiatus between units a and b iii wetlands and smaller lakes formed in the uplifted area between 42 and 36 cal ka bp unit b iv deposition of glaciolacustrine clays at kriegers flak demonstrates that a growing sis dammed kattegat and the baltic basin c 28 5 to 26 ka the new evidence from kriegers flak provides a solid framework for future mis 3 palaeoenvironmental reconstructions in the circum baltic area

determination of deviatoric stress tensors based on inversion of calcite twin data from experimentally deformed monophase samples preliminary results abstract following previous successful paleo stress determinations from numerically generated aggregates and naturally deformed samples preliminary results about stress reconstructions based on inversion of calcite twin data from experimentally deformed monophase samples are reported this new study carried out on samples of carrara marble and crinoidic limestone from eastern france provides a test of the validity of stress reconstructions using inverse methods which had not been properly calibrated before the percentages of correlated twins are discussed for each stress tesnor and the range of uncertainties on the determination of stress orientations and differential stress magnitudes is evaluated

palaeostress estimation using calcite twinning experimental calibration and application to nature abstract by means of high temperature deformation experiments on calcite rocks of different grain sizes we have established the relationships between differential stress and twinning incidence twin density and volume fraction and the way that these relationships depend on grain size both twinning incidence and volume fraction increase with grain size at a constant level of differential stress log twin density is proportional to stress but is independent of grain size at a given grain size volume fraction of twinning increases non linearly with differential stress twinning activity measured by twinning incidence increases linearly with stress the behaviour of each of these parameters is independent of temperature strain and strain rate these relationships can be used as a basis for the estimation of palaeostress values in naturally deformed calcite rocks this is illustrated by a study of twinning activity in limestones close to thrust faults in the cantabrian zone of the variscan orogenic belt in northwestern spain high peak differential stresses were measured ranging from 150 to 250 mpa using the turner dynamic analysis technique however it is clear that shear stresses resolved parallel to the fault planes were very low the attainment of high stress differences when the resistance to faulting was low is attributed either to bending forces induced during the motion of the non planar surfaces relative to each other or to the stress peak being attained prior to the localization of deformation onto the fault surfaces

controls on shell mg ca and sr ca in cultured planktonic foraminiferan globigerinoides ruber white mg ca and sr ca ratios were determined on a single species of planktonic foraminiferan globigerinoides ruber white collected from the gulf of eilat and cultured in seawater at five different salinities 32 to 44 five temperatures 18 to 30 c and four ph values 7 9 to 8 4 the mg ca temperature calibration of cultured g ruber with an exponential slope of 8 3 c agrees well with previously published calibrations from core tops and sediment traps however the dependence of mg ca on salinity with an exponential slope of 5 3 psu is also significant and should be included in the calibration equation with this purpose we calculated a calibration equation for g ruber dependent on both temperature and salinity within the 95 confidence limits mg ca mmol mol exp 0 06 0 02 s psu 0 08 0 02 t c 2 8 1 0 r2 0 95 the influence of ph on mg ca ratios is negligible at ambient seawater ph 8 1 to 8 3 however we observe a dominating ph control on shell mg ca when the ph of seawater is lower than 8 0 sr ca in g ruber shows a significant positive correlation with average growth rate presumably part of the variability in shell sr ca in the geological record is linked to changes in growth rates of foraminifera as a response to changing environmental conditions

middle weichselian palaeolacustrine basin in the venta river valley and vicinity northwest lithuania exemplified by the purviai outcrop abstract investigations of the middle weichselian sequences in the baltic region are of great importance for determination of the extent of the middle weichselian glaciation especially during mis 4 and palaeogeography of mis 3 an extensive area of distribution of palaeolacustrine sediments sand clay silt with humus and interlayers of peat ca 80 km 2 occurring under the relief forming upper weichselian till was determined in the vicinity of venta northwest lithuania in the course of geological mapping the investigations of the purviai outcrop in the venta river valley included pollen analysis lithology determination of mollusca and radiocarbon dating the sequence of the purviai outcrop reflects the presence of nonglacial palaeoenvironments before the late weichselian ice advance two intervals containing pollen and spores lpaz i and lpaz ii were identified and interpreted as two separate climatostratigraphic events lpaz i showing severe conditions cryomer and lpaz ii showing slight climatic improvement thermomer during the deposition of the lpaz i the main composition of the local vegetation included cyperaceae and artemisia the pollen record of lpaz 1 shows cold wet severe periglacial conditions with an open landscape and sedge communities during the formation of lpaz ii the surrounding territory was covered by park tundra with birch pine and some admixture of scattered spruce dwarf birch and juniper two radiocarbon dates from the sediments containing pollen and spores were obtained 33 540 370 calbp and 33 800 460 calbp the cryomer i lpaz and the thermomer ii lpaz of the purviai outcrop are tentatively correlated respectively with the nemunas 2d cryomer and the mickunai 3 thermomer in south east lithuania where these units form a middle weichselian interstadial complex tentatively the purviai units are correlated with the denekamp interstadial complex the presence of the venta palaeolacustrine basin implies that north lithuania was ice free 33 ka bp

mg ca paleothermometry in high salinity environments planktonic foraminiferal mg ca ratios have become a fundamental temperature proxy in past climate reconstructions however in the highly evaporative seas of the tropics and subtropics anomalously high planktonic foraminiferal mg ca ratios arise possibly linked to high salinities the extent to which salinity affects mg uptake into foraminiferal calcite remains disputed some studies suggest only minor salinity effects whereas others suggest a dominant role here we present new data from the highly saline 40 red sea which separate pure foraminiferal calcite from other phases the results show that high mg ca ratios 7 to 13 mmol mol found by conventional analysis of planktonic foraminifera from a red sea sediment core are not caused by increased mg uptake into foraminiferal calcite in a high salinity setting e g beyond those predicted by culturing studies but instead result from secondary high mg calcite overgrowths the overgrowths likely formed near the sediment seawater interface from caco3 supersaturated interstitial seawater

marginal marine environments of the skagerrak and kattegat a baseline study of living stained benthic foraminiferal ecology this is the first detailed investigation of the distribution and ecology of living stained shallow water 0 6 m foraminifera along the skagerrak kattegat coast eastern north sea a total of 25 species 13 agglutinated 12 calcareous are common in the 169 sediment surface samples which were collected from 27 geographic areas the sediment grain size and total organic carbon toc content are strongly variable and the salinity and temperature ranges were 10 31 and 9 30 c respectively at the time of sampling july to october but temperatures down to freezing occur during the winter the species are divided into six environmental categories of which the first five comprise euryhaline and the sixth essentially stenohaline taxa 1 species associated only with marsh plants 2 species basically but not entirely associated with marsh plants 3 species basically but not entirely restricted to non marsh areas 4 species solely recorded in non marsh intertidal to subtidal environments 5 species restricted to subtidal areas 6 species basically living in the most open marine areas in this region marshes have a patchy distribution and they are small and compressed due to low tidal ranges 80 mud ammoscalaria runiana is common only in coarse grained sediments 20 mud with low toc 0 7 there are no marked biogeographic boundaries within the skagerrak kattegat area but 10 of the 25 commonly occurring species have not been reported from the adjacent baltic sea probably partly due to the brackish character of the water there the southern limits of distribution of the northern species elphidium albiumbilicatum ammotium cassis and ophthalmina kilianensis are in the kattegat baltic sea

calcite twins from microveins as indicators of deformation history abstract in order to investigate whether the evidence of the deformation history is preserved in the microvein calcite twinning microstructures several families of calcite veins have been studied from weakly deformed mesozoic limestones of the western iberian chain eastern iberian peninsula the maximum shortening directions established with this method correspond to the previously established paleostress evolution of this chain the reconstructed stress regimes evolve from predominantly compressional four compressional episodes with the maximum shortening direction oriented successively nw se n s ne sw and e w to extensional the established orientations of maximum shortening axes are consistent with the directions of paleostrains that have been independently deduced from stylolites and fault striations in the same region moreover the results clearly show that the e twins record some paleostress orientations that are not registered in the studied area by fault population analysis in this sense the e twins record older paleostress orientations than the small faults probably because the faults were reactivated several times and the twins were not modified since their formation the calculated values of twin strains 1 differential stress magnitudes 62 mpa and the existence of type i twins formed below 200 c confirm that this region was slightly deformed under low p t conditions

drumlinised glaciofluvial and glaciolacustrine sediments on the smaland peneplain south sweden new information on the growth and decay history of the fennoscandian ice sheets during mis 3 abstract dug trenches in sediment cored drumlins on the smaland peneplain southern sweden occurring intermixed with rock cored drumlins revealed sedimentary successions and facies suggesting that the core sediments were primarily deposited proglacially both in glaciolacustrine settings as delta front and more distal deeper water sediments and as glaciofluvial braidplain sediments from the relationship between the drumlin sorted sediment cores and their surficial drape by a till carapace it is concluded that erosion was the main drumlin forming process here reshaping the original sediment morphology into streamlined landforms after which a more or less thick traction till was deposited over the eroded and or deformed ice bed interface drumlin formation probably took place during the last deglaciation over the area the drumlin core sediments in 14 excavated trenches were dated by optically stimulated luminescence osl most retrieved ages fall into two distinct groups both within marine isotope stage 3 c 60 30 ka when plotted as mean osl ages for each site all but two sites fall either into an older age group c 48 56 ka seven sites or into a younger age group c 28 38 ka five sites these age intervals correlate well with the suggested time spans for the ristinge and klintholm ice advances in denmark by ice flowing from the baltic basin westwards terminating in fan shaped patterns these interstadial ice advances in the southwestern sector of the fennoscandian ice sheet give rise to enigmatic questions on the physics and mechanics of ice sheet build up and decay especially as palaeoenvironmental data for northern fennoscandia suggest widespread ice free conditions within roughly the same time fame as the recorded ice advances in the south

benthic foraminiferal mg ca paleothermometry a revised core top calibration core top samples from different ocean basins have been analyzed to refine our current understanding of the sensitivity of benthic foraminiferal calcite magnesium calcium mg ca to bottom water temperatures bwt benthic foraminifera collected from hawaii little bahama bank sea of okhotsk gulf of california ne atlantic ceara rise sierra leone rise the ontong java plateau and the southern ocean covering a temperature range of 0 8 to 18 c were used to revise the cibicidoides mg ca temperature calibration the mg ca bwt relationship of three common cibicidoides species is described by an exponential equation mg ca 0 867 0 049 exp 0 109 0 007 bwt stated errors are 95 ci the temperature sensitivity is very similar to a previously published calibration however the revised calibration has a significantly different preexponential constant resulting in different predicted absolute temperatures we attribute this difference in the preexponential constant to an analytical issue of accuracy some genera notably uvigerina show apparently lower temperature sensitivity than others suggesting that the use of constant offsets to account for vital effects in mg ca may not be appropriate downcore mg ca reproducibility as determined on replicate foraminiferal samples is typically better than 0 1 mmol mol 1 2 s e thus considering the errors associated with the cibicidoides calibration and the downcore reproducibility bwt may be estimated to within 1 c application of the revised core top mg ca bwt data to cenozoic foraminiferal mg ca suggests that seawater mg ca was not more than 35 lower than today in the ice free ocean at 50 ma

osl dating of middle weichselian age shallow basin sediments in western latvia eastern baltic abstract this paper presents the results of the first attempt to date the quaternary sediments of western latvia in the southeast baltic region using luminescence the analyses have been carried out on sandy sediments of the jurkalne formation that are located between upper and lower scandinavian sourced tills previous publications on the origin of the quaternary sediments in the region are reviewed and it is found that there are a wide range of explanations for their processes of formation and their age of formation it is concluded that although the sandy sediments were deposited in freshwater environment although they contain both marine and freshwater fauna and flora a property that is explained by derivation and glaciotectonic deformation and mixing the samples used for dating were collected from surface exposures and boreholes and yield results that range in age from 52 10 ka bp to 26 4 1 ka bp as a result of this study it is suggested that the dated sediments were deposited in a freshwater basin during mis 3 and are overlain by a till deposited by scandinavian ice during the late weichselian mis 2 lgm the underlying till is attributed to a middle weichselian glaciation and tentative suggestions are presented for the age of other deposits that underlie the dated sediment

foraminiferal mg ca increase in the caribbean during the pliocene western atlantic warm pool formation salinity influence or diagenetic overprint we constructed a high resolution mg ca record on the planktonic foraminifer globigerinoides sacculifer in order to explore the change in sea surface temperature sst due to the shoaling of the isthmus of panama as well as the impact of secondary factors like diagenesis and large salinity fluctuations the study covers the latest miocene and the early pliocene 5 6 3 9 ma and was combined with 18o to isolate changes in sea surface salinity sss before 4 5 ma sstmg ca and sss show moderate fluctuations indicating a free exchange of surface ocean water masses between the pacific and the atlantic the increase in 18o after 4 5 ma represents increasing salinities in the caribbean due to the progressive closure of the panamanian gateway the increase in mg ca toward values of maximum 7 mmol mol suggests that secondary influences have played a significant role evidence of crystalline overgrowths on the foraminiferal tests in correlation with aragonite sr ca and productivity cyclicities indicates a diagenetic overprint on the foraminiferal tests laser ablation inductively coupled plasma mass spectrometry analyses however do not show significantly increased mg ca ratios in the crystalline overgrowths and neither do calculations based on pore water data conclusively result in significantly elevated mg ca ratios in the crystalline overgrowths alternatively the elevated mg ca ratios might have been caused by salinity as the 18o record of site 1000 has been interpreted to represent large fluctuations in sss and cultivating experiments have shown an increase in mg ca with increasing salinity we conclude that the mg ca record 4 5 ma can only reliably be considered for paleoceanographical purposes when the minimum values not showing any evidence of secondary influences are used resulting in a warming of central caribbean surface water masses after 4 5 ma of 2 c

woolly mammoth mammuthus primigenius blum and its environment in northern europe during the last glaciation abstract woolly mammoths were large herbivorous cold adapted mammals of the late pleistocene the diet and habitat requirements of the species set certain constraints on the palaeoenvironments it could occupy the relationship between the mammoth s shifting range and changing environments can be explored using independent data on ice sheet configuration temperature and vegetation provided the locality and age of the fossil remains can be validated here we present a comprehensive record of occurrence of the woolly mammoth in the circum baltic region of northern europe during the last glaciation based on a compilation of radiocarbon dated remains the record shows that the mammoth was widespread in northern and north eastern europe during marine isotope stage 3 mis 3 at 50 000 30 000 calibrated years ago 50 30 ka the presence of the species up to 65 n latitude supports the restriction of the scandinavian ice sheet sis during mis 3 the widest distribution range round 30 ka was followed by a decline that led to the disappearance of mammoths from the area during the maximum extent of the sis from 22 to 18 ka the woolly mammoth re colonized the baltic region and southern scandinavia after the onset of the late glacial deglaciation at 17 ka the late glacial record suggests a markedly fluctuating population changing its range in tune with the rapid environmental changes the last appearance of mammoth in our study region was in estonia during the younger dryas greenland stadial 1 gs1 at about 12 ka the two major periods of occurrence during mis 3 and the late glacial stadial suggest that mammoth had a wide tolerance of open to semi open tundra and steppe tundra habitats with intermediately cold climate whereas the 22 18 ka disappearance suggests a major southward and or eastward retreat in response to extremely cold glacial conditions near the sis margin the final regional extinction correlates with the re forestation during the rapid warming at the younger dryas holocene boundary

a review of the history of the baltic sea 13 0 8 0 ka bp abstract the dynamic history of the baltic sea during the millennia following the last deglaciation has been one of the main topics for many generations of quaternary geologists around the baltic sea based on the present state of knowledge and certain hypotheses a model for the development during the baltic ice lake yoldia sea and ancylus lake stages are presented the oresund strait was the threshold of the initial stage of the baltic ice lake and was eroded down to bedrock as a result of the isostatic uplift the emerging threshold forced the baltic ice lake to rise above sea level at ca 12 0 ka bp this gradual up damming ended at ca 11 2 ka bp when the large glacial lake was lowered 5 10m by possible subglacial drainage at mt billingen a glacial readvance during the younger dryas ended a ca 400 year long land bridge between sweden and the continent by blocking the former drainage route once again the baltic ice lake had to rise above sea level to be drained over the oresund strait at ca 10 5 ka bp a gradual ice recession began and 200 years later when the receding ice sheet could not withhold the up dammed water masses the final drainage of the baltic ice lake occurred which rapidly lowered the water level within the baltic basin with ca 25 m and ended the baltic ice lake stage the next stage the yoldia sea was characterized by a complex pattern of relative sea level changes with large differences within the baltic basin a very restricted baltic sea in the south and thus an extensive landbridge at ca 9 9 ka bp a short 100 200 years saline ingression is seen in the baltic sediment records from stockholm in the north to the southernmost parts of the yoldia sea the gradually shallower strait in south central sweden the narke strait ended the saline influence 300 400 years later the two remaining outlets west of lake vanern gota alv and otteid steinselva had become too shallow to swallow the outflowing yoldia sea waters at this stage the baltic lake vanern level could thus not fall in pace with the relative sea level fall outside the outlet areas this was the isolation of lake vanern and the baltic from the sea and the beginning of the ancylus lake since the water depth of the larger gota alv outlet had to be more or less maintained the ancylus lake level had to rise in pace with the uplift of the outlet region this caused a significant and rapid transgression 10 30 m in ca 300 years in the southern baltic which flooded large areas with recently immigrated pine forests since the oresund strait during the yoldia sea stage had been uplifted more than southerly areas the ancylus transgression ended with a new drainage pathway at ca 9 2 ka bp through the darss sill area in the southern baltic and northwards through the store belt strait this so called dana river had cut off the former large land bridge the quaternary deposits of this new threshold were eroded and a fairly rapid regression set in at ca 9 0 ka bp the dana river had eroded down to the sea level which isolated lake vanern from the ancylus lake and created a land bridge between southern sweden and northwards ca 800 years later when the sea level rose above the oresund threshold marine water could enter the baltic and at ca 8 0 ka bp brackish water characterized the southern baltic this marks the end of the ancylus lake

the impact of salinity on the mg ca and sr ca ratio in the benthic foraminifera ammonia tepida results from culture experiments abstract over the last decade sea surface temperature sst reconstructed from the mg ca ratio of foraminiferal calcite has increasingly been used in combination with the 18o signal measured on the same material to calculate the 18ow a proxy for sea surface salinity sss a number of studies however have shown that the mg ca ratio is also sensitive to other parameters such as ph or co 3 2 and salinity to increase the reliability of foraminiferal mg ca ratios as temperature proxies these effects should be quantified in isolation individuals of the benthic foraminifera ammonia tepida were cultured at three different salinities 20 33 and 40 psu and two temperatures 10 15 c the mg ca and sr ca ratios of newly formed calcite were analyzed by laser ablation icp ms and demonstrate that the mg concentration in a tepida is overall relatively low mean value per experimental condition between 0 5 and 1 3 mmol mol when compared to other foraminiferal species sr being similar to other foraminiferal species the mg and sr incorporation are both enhanced with increasing temperatures however the temperature dependency for sr disappears when the distribution factor dsr is plotted as a function of calcite saturation state this suggests that a kinetic process related to is responsible for the observed dependency of sr incorporation on sea water temperature the inferred relative increase in dmg per unit salinity is 2 8 at 10 c and 3 3 at 15 c for the salinity interval 20 40 psu this implies that a salinity increase of 2 psu results in enhanced mg incorporation equivalent to 1 c temperature increase the dsr increase per unit salinity is 0 8 at 10 c and 1 3 at 15 c for the salinity interval 20 40 psu

an absolute chronology for the raised beach and associated deposits at sewerby east yorkshire england the raised beach sediments revealed in the cliffs at sewerby east yorkshire are widely regarded as ipswichian in age previously reported evidence for this dating is reviewed and new results from a range of luminescence dating techniques applied to the blown sand deposit overlying the raised beach are reported these provide the first absolute date for the sewerby site of 120 84 11 82 ka which places the blown sand at the boundary between oxygen isotope stages ois 5e and 5d as the underlying raised beach is little older than the blown sand it probably formed during ois stage 5e as suggested by the faunal evidence

critical re evaluation of differential stress estimates from calcite twins in coarse grained limestone abstract comparison of two techniques to estimate differential stress magnitude based on calcite twinning reveals significantly different calculated values of differential stress for limestone experimentally and naturally deformed at low temperature this inequality may be due to fundamental differences between the rock type marble versus limestone and deformation temperatures above and below 200 c for samples used in technique calibration versus samples used in testing and application a technique that was empirically derived from marble experimentally deformed at 200 800 c yields values of differential stress that are factors of 2 to 9 times larger than maximum differential stress measured during experimental deformation of limestone at low temperature

rapid sea level fall and deep ocean temperature change since the last interglacial period we have dated huon peninsula papua new guinea and barbados corals that formed at times since the last interglacial period applying both 230 th and 231 pa dating techniques as a test of age accuracy we show that marine isotope stage mis 5e ended prior to 113 1 8 0 7 kyr when sea level was 319 m during mis 5b sea level was 357 m at 92 6 8 0 5 kyr having dropped about 40 m in approximately 10 kyr during the mis 5c 5b transition sea level then rose more than 40 m during the mis 5b 5a transition also in about 10 kyr mis 5a lasted until at least 76 2 8 0 4 kyr at a level of 324 m at that time combined with earlier data that places mis 4 sea level at 381 m at 70 8 kyr our late mis 5a data indicate that sea level fell almost 60 m in less than 6 kyr 10 6 m kyr during the mis 5 4 transition the magnitude of the drop is half that of the glacial interglacial amplitude and approximatelyequivalent to the volume of the present dayantarctic ice sheet during this interval the minimum average rate of net continental ice accumulation was 18 cm yr likely facilitated by efficient moisture transport from lower latitudes at three specific times 60 6 8 0 3 50 8 8 0 3 and 36 8 0 2 kyr during mis 3 sea level was between 385 and 374 m sea level then dropped to 3107 m at 23 7 8 0 1 kyr early in mis 2 before dropping further to last glacial maximum lgm values and then rising to present values during the last deglaciation times of rapid sea level drop correspond to times of high winter insolation at low northern latitudes and high winter latitudinal gradients in northern hemisphere insolation supporting the idea that these factors mayhave resulted in high water vapor pressure in moisture sources and efficient moisture transport to high latitude glaciers therebycontributing to glacial buildup we combined our sea level results with deep sea n 18 o records as a means of estimating the temperature and ice volume components in the marine n 18 o record this analysis confirms large deep ocean temperature shifts following mis 5e and during termination i deep ocean temperatures changed bymuch smaller amounts between mis 5c and 2 maximum temperature shift in the deep pacific is about 2 whereas the shift at a site in the atlantic is 4 under glacial conditions temperatures at both sites are near the freezing point the shift in the atlantic is likelycaused bya combination of changing proportions of northern and southern source waters as well as changing temperature at the sites where these deep waters form

millennial scale variability during the last glacial the ice core record the oxygen isotope records from greenland ice cores show a very strong reproducible pattern of alternation between warm greenland interstadials gi and cold greenland stadials gs at millennial scale during the last glacial period here we summarise what is known about this variability from ice core records the typical cycle has a sawtooth pattern with a very rapid warming event occurring in a few decades a slow cooling trend and then a final fast cooling 25 such events have been numbered in the last glacial the recent gicc05 age scale provides the best available age scale that can be directly applied to this stratigraphy and we summarise the timing of the warming events and the length and strength of each event the greenland stratigraphy can be transferred to other records if we make assumptions about the contemporaneous nature of rapid events in different archives other parameters such as the snow accumulation rate and the concentration of terrestrial dust and sea salt recorded in the greenland cores also show a strong contrasting pattern between gi and gs methane concentrations are generally high during gi and lower during gs with the increase from gs to gi occurring within a century antarctic ice cores show a different pattern each gi has an antarctic counterpart but antarctica appears to warm while greenland is in a gs and cool during gi these changes are consistent with a mechanism involving ocean heat transport but the rapid nature of warmings poses a challenge for modellers while the rapid methane changes pose questions about the pattern of land biosphere emissions during the glacial that are also relevant for understanding glacial interglacial methane variability

reconciliation of late quaternary sea levels derived from coral terraces at huon peninsula with deep sea oxygen isotope records a major discrepancy between the late quaternary sea level changes derived from raised coral reef terraces at the huon peninsula in papua new guinea and from oxygen isotopes in deep sea cores is resolved the two methods agree closely from 120 ka to 80 ka and from 20 ka to 0 ka ka 1000 yr before present but between 70 and 30 ka the isotopic sea levels are 20 40 m lower than the huon peninsula sea levels derived in earlier studies new high precision u series age measurements and revised stratigraphic data for huon peninsula terraces aged between 30 and 70 ka now give similar sea levels to those based on deep sea oxygen isotope data planktonic and benthic 18o data using the sea level and deep sea isotopic data oxygen isotope ratios are calculated for the northern continental ice sheets through the last glacial cycle and are consistent with results from greenland ice cores the record of ice volume changes through the last glacial cycle now appears to be reasonably complete