organic geochemical proxies of paleoceanographic paleolimnologic and paleoclimatic processes abstract organic matter constitutes a minor fraction of marine and freshwater sediments yet its important contribution to the sedimentary record can be used to reconstruct marine and continental paleoenvironments the organic matter content of sediments is the residue of past biota the amounts and types of organic matter present in sediments consequently reflect environmental conditions that impacted ecosystems at different past times general sources of the organic matter are inferred from bulk properties such as elemental compositions carbon and nitrogen stable isotope ratios rock eval pyrolysis data and organic petrography details of organic matter origins are refined by analyses of biomarker molecular compositions source changes are proxies for fluctuations in sea level oceanic surface currents and continental climates algal paleoproductivity rates are indicated by organic carbon mass accumulation rates and carbon and nitrogen stable isotopic compositions these parameters record past availability of nutrients and therefore are proxies of surface mixing in the oceans and amount of land runoff to lakes sea surface paleotemperatures are recorded by the number of carbon carbon double bonds in lipid biomarkers produced by marine algae larger proportions of the double bonds are proxies for the cooler surface waters that accompanied periods of global glaciation and intervals of enhanced upwelling the 13c and d values of plant organic matter record past concentrations of carbon dioxide in the atmosphere and changes in delivery of atmospheric moisture respectively diagenesis which causes the concentration and composition of organic matter in sedimentary settings to differ from those of the original biologically synthesized materials can bias organic geochemical paleoenvironmental records the magnitude of this potential source of misinformation must always be considered and evaluated comparison of multiple organic geochemical proxies of past conditions helps to compensate for the effects of diagenetic alterations and thereby to improve interpretations of paleoenvironmental change

modern reindeer and mice revised phosphate water isotope equations abstract the oxygen isotope composition of bone and tooth phosphate of 34 mice specimens pitymus sp microtus arvalis and arvicola terrestris coming from seven different locations in italy germany and switzerland was measured by means of well established techniques these measurements were carried out with the purpose of establishing quantitative relationships between the 18op from different mice genera and the mean 18ow values and to compare these data to previous measurements carried out on various specimens belonging to the genus apodemus the three genera studied showed a similar behaviour when compared to the mean 18ow values the slope of the equation calculated for these three genera is significantly different from the slope obtained from apodemus specimens reconsidering the 18ow values suggested in the case of apodemus due to the small number of data available at that time it seems that these values are too negative by 0 5 to about 1 5 if so the apodemus equation becomes almost identical to the equation calculated for the new mice values and consequently one could conclude that several micromammal genera and species might behave in the same way and obey the same relationship with the mean 18ow values a set of 25 samples of modern reindeer skeletal material from spitzbergen russia and siberia was also studied with the aim of improving the reindeer isotope equation obtained from a previous study in fact the slope of that equation was somehow uncertain due to a rather large range of isotope values obtained from each group of reindeers coming from the same location the new results confirm such anomalous behaviour already shown by other mammals and probably related to dietary behaviours water fluxes with the environment and isotopic composition of ingested food and water rather than to imperfect equilibrium conditions with environmental water however the equation calculated from both the old and new statistically more significant isotope results is not far from the previous one

geochemistry of thermal springs alhama de granada southern spain abstract the waters of the thermal springs at alhama de granada vary in temperature between 27 and 45 c temporal changes in the composition of the principal spring banos viejos indicate that a small degree of mixing may occur between deep thermal waters and shallow groundwater slight compositional variations also occur between the various thermal springs in the study area these spatial variations are due to the different local hydrodynamic conditions in the springs towards the north in less hydraulically transmissive rocks cooling of the rising water is more noticeable as are ion exchange and processes of so 4 reduction the chemical composition of the water is related to the dissolution of evaporites so 4 and cl salts carbonates and silicates and to the possible existence of sources of s within the rock estimates of the mean residence times have been obtained based on 14 c dic and t the state of thermodynamic equilibrium at the spring discharge was calculated using the solmineq 88 program the results indicate that all the samples are supersaturated with respect to quartz chalcedony cristobalite calcite aragonite and dolomite and undersaturated with respect to gypsum anhydrite and halite the use of different geothermometers and modelling of saturation indices for quartz albite and anhydrite indicate temperatures of about 110 c

the retention of primary oxygen isotope compositions of fossil elephant skeletal phosphate fossil elephant remains from sediments of plio pleistocene age in the vicinity of lake turkana kenya provide insights into the ability of the phosphate oxygen system to preserve original 18o values 18op in the depositional environment individual fossil specimens exhibit systematic variations in the 18op values of their various tooth and bone components differences in 18op values between these skeletal components can be as high as 3 6 despite the fact that equivalent phases for individual modern elephants have 18op values which vary by less than 0 6 xrd traces of the different skeletal phases of modern and fossil samples also infer differential preservation of primary apatite crystallinities among the various fossil phases fossil samples of dentine cementum and bone have x ray spectra with sharper and more intense peaks compared to their modern counterparts but little change in crystallinity is observed for fossil enamel samples a model based on the premise that the enamel phase preserves primary isotope signatures and that the accompanying skeletal phases are partially re equilibrated with the fluids associated with the microbial decomposition of the elephant s carcass is consistent with the features of the 18op dataset this isotopic evidence in conjunction with the physical and chemical attributes of enamel has led us to postulate that enamel could be preserving primary isotope signatures while other skeletal components are affected to varying degrees by alteration processes in the burial environment

genesis and evolution of strontium deposits of the granada basin southeastern spain evidence of diagenetic replacement of a stromatolite belt abstract there are important strontium deposits in the granada basin the most noteable of which montevives has an annual production of approximately 50 000 tons of almost pure celestite two types of mineralization can be recognized a primary variety consisting of stromatolitic carbonate that has been partially replaced by celestite and a secondary variety consisting of celestite pebble karst deposits both are included in an evaporitic messinian succession the primary variety of mineralization is within carbonates that interfinger with and prograde across gypsum deposits the development of these deposits can be interpreted in the context of the general evolution of the granada basin during late tortonian and messinian times open marine conditions prevailed during the late tortonian during the transition from tortonian to messinian a restriction of the basin resulted in evaporite sedimentation with stromatolites thriving at the basin s margin the stromatolites were distributed along a coastal belt that was limited on the east by the tectonically active sierra nevada with its local alluvial fans runoff from the sierra nevada produced a freshwater lens and surface salinities that permitted the development of stromatolites rather than the accumulation of gypsum the replacement of stromatolitic carbonate by celestite occurred within the mixing zone of the coastal aquifers during sedimentation and or early diagenesis an essentially marine origin is considered for the strontium supplementary influxes from continental weathering are also thought to have been produced further restriction of the granada basin led to complete desiccation and the deposition of a 20 m thick halite layer later gypsum deposits were exposed and resulting cavities dolinas were filled with celestite pebbles the return of sediment accumulation within lakes buried and preserved these deposits

late miocene early pliocene climatic evolution of the granada basin southern spain deduced from the paleoecology of the micromammal associations this paper analyses the relationship between the evolution of the late miocene and early pliocene rodent and insectivore assemblages from the granada basin southern spain and climate changes these climatic changes in terms of humidity and temperature fluctuations are inferred from variations of the relative abundances of taxons with definite ecological preferences there is a general tendency towards a temperature increase from the latest tortonian middle turolian to the messinian late turolian and towards a decrease from the mio pliocene boundary latest turolian earliest ruscinian to the end of the zanclean late ruscinian dry conditions predominate in the latest tortonian middle turolian at the beginning of the messinian late turolian there was a significant increase in humidity followed by an aridification throughout the end of the messinian and zanclean late turolian and ruscinian these climatic variations are in accordance with the sedimentary evolution of the basin and agree with the climatic interpretations inferred from the shallow marine carbonate sediments temperate tropical deposited in the marine basins of southeastern spain during the studied time interval

a stable isotope study of fossil mammal remains from the paglicci cave southern italy 13 to 33 ka bp palaeoclimatological considerations abstract a set of 102 samples of fossil skeletal remains of mammals from a sediment sequence from the paglicci cave in southern italy was studied for the oxygen isotopic composition of bone and tooth phosphate the samples belong to cervus elaphus bos primigenius and equus caballus and come from various levels of a succession spanning about 33 to 13 ka bp calibrated 14c ages on the basis of x ray diffraction studies on every sample most of them show no evidence of recrystallisation and may thus be considered reliable for isotopic study 18op values range from 16 8 o to 20 5 o v smow cervus and bos samples show trends in their isotopic values that are similar to each other the 18ow calculated from their 18op p values using previously established equations form sections of a climatic curve that agree quite well with the palaeoclimatological curve obtained from the grip ice core despite minor differences in the timing and intensity of some climatic events despite the relatively low latitude of the area and its central position in the mediterranean basin we may conclude that major climatic changes left their signature on the isotopic composition of the samples studied

environmental conditions vs landscape assessment of the factors that influence small mammal fauna distribution in southern iberia during the latest messinian by mean of stable isotopes tropical conditions during the late miocene in southwestern europe influenced the continental environments although there are previous qualitative environmental interpretations of these continental landscapes during the late miocene quantitative environmental and paleohydrological data are scarce a very long sequence of small mammals allowed to date the different continental drainage stages of the granada basin from latest tortonian to the holocene and to reconstruct qualitatively its environmental evolution the study of the isotopic record of these fossil small mammals and sediments in the stratigraphic sequence of a latest messinian paleo lake in the granada basin has provided quantitative environmental and paleohydrological data in order to know if the fluctuations in the faunal distribution were mainly influenced by the paleogeographic configuration such as changes in the landscape of the basin or by the climatic conditions open habitats with c3 plants predominated estimated quantitative data suggest an oxygen isotopic composition of meteoric waters ranging from 4 9 to 3 9 past temperatures from 2 5 c to 4 7 c higher than the current ones and summer relative paleohumidity from 60 to 70 in this context changes in the landscape such as the reduction of the lacustrine system caused by tectonic activity would affect taxa with high dependence on humid conditions

stable isotopic evidence for terrestrial latitudinal climate gradients in the late miocene of the iberian peninsula abstract the late neogene of the mediterranean region is marked by significant faunal and floral turnover in terrestrial ecosystems paleogeographic and paleoceanographic changes associated with the messinian salinity crisis msc and regional climate transition associated with the onset of northern hemisphere glaciation in this paper we report stable oxygen isotope compositions 18o of terrestrial mammal faunas from the late miocene pliocene and pleistocene of spain and compare these data with late miocene mammal 18o values from northern libya since tooth enamel 18o from modern horses has been demonstrated to be a reasonable proxy for the 18o of local meteoric water which is in turn strongly dependent on mean annual temperature mat we use the 18o of fossil horse tooth enamel to estimate mat our paleotemperature reconstructions are consistent with global cooling during the late cenozoic with mat for the late miocene that is warmer than today by 1 2 c in ne spain and by 4 5 c in se spain the difference of 8 9 c between ne and se spain for the late miocene is 60 greater than the mat difference between these same areas today the 18o values from libya are lower than those for southern spain and may suggest cooler and or wetter climates in northeastern africa during the latest miocene and early pliocene we examined intrafaunal 18o patterns to make interpretations about paleoecology and to qualitatively assess paleoaridity comparisons of 18o values between clades are consistent with a semi aquatic lifestyle for anthracotheres hippopotamids and castorids we also compare intra tooth samples of enamel and dentine to examine possible diagenetic alteration of these materials comparisons of enamel and dentine 18o suggest slight diagenetic alteration of dentine but we demonstrate that these 18o values can be used to reconstruct reasonable values of diagenetic water 18o overall our data do not support large climatic changes in the iberian peninsula during the msc but are consistent with long term global cooling and sharper latitudinal climate gradients in spain during the neogene

small mammals from the early pleistocene of the granada basin southern spain the pliocene and pleistocene continental sedimentary records of the western sector of the granada basin southern spain consist of alternating fluvial and lacustrine palustrine sediments two quaternary sections from this sector have been sampled huetor tajar and tojaire they have yielded remains of rodents insectivores and lagomorphs the presence in the huetor tajar and tojaire sections of mimomys apodemus atavus castillomys rivas and two different species of allophaiomys indicates an early pleistocene age these deposits which are related to a fluvio lacustrine system can be differentiated from an older pliocene braided fluvial system their dating has important repercussions on the paleogeographic reconstruction of the basin the conditions inferred from the ecological preferences of the small mammal associations are wet and cold these associations suggest a predominance of open herbaceous habitats followed by forested habitats semiaquatic habitats are the least represented

marbles from roman hispania stable isotope and cathodoluminescence characterization abstract pure white marble has been considered a valuable ornamental and architectural material since ancient times many scientific techniques have been used to create an extensive data base of finger prints characterizing white marbles from the major classical quarries however determining the provenance of white marbles is a difficult task due to their similarity in physical and chemical parameters three techniques petrography cathodoluminescence and stable c and o isotopes have been used to characterize white marbles from the ancient quarries of the iberian peninsula maximum grain size texture and isotopic composition can be used to identify the different quarries each area is generally represented by several cathodomicrofacies but quantitative cl analysis is also helpful in distinguishing those quarries for which the data provided by other techniques are not sufficiently diagnostic the database and the discriminating criteria presented in this study have been tentatively applied to some ancient sculptures from the national museum of roman art in merida spain

oxygen isotope analyses of co existing carbonate and phosphate in biogenic apatite a way to monitor diagenetic alteration of bone phosphate abstract the oxygen isotopic composition of phosphate 18 op and structural carbonate 18 oc of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries these two variables are highly correlate r 2 0 98 and the calculated best fit of linear regression is very similar to the equation calculated from the phosphate and carbonate palaeotemperature equations 1 2 according to previous measurements 3 6 on fossils of different ages from different areas it seems quite improbable to find isotopically altered skeletal remains showing a good correlation between 18 op and 18 oc as is the case with modern samples it therefore seems possible at least in some cases to use these measurements for monitoring fossil bone and tooth diagenetic alteration when a set of points lie on the equilibrium line or close to it the 18 o values could be considered close to the original values in contrast when the points lie to the left or to the right of this line this probably means that the values are diagenetically modified due to interaction with meteoric water or 18 o enriched water respectively

coral reefs in coarse terrigenous sedimentary environments upper tortonian granada basin southern spain abstract during the upper tortonian coral reefs developed on fan deltas and braid deltas along the active eastern edge of the granada basin the corals grew in environments characterized by deposition of coarse sands and conglomerates frequency of sedimentation together with sea level rises controlled reef development and determined the architecture and composition of the carbonate deposits in direct contrast to these reefs others flourished at the same time along stable coastal margins of the basin their structure was influenced mainly by periodic rises in sea level the mapping of all these reefs serves as an accurate guide to the upper tortonian geography of the granada basin

carbon isotope composition of lake sediments in relation to lake productivity and radiocarbon dating abstract carbon 13 profiles and radiocarbon dates were obtained from two canadian kettle basins having similar geological and hydrological characteristics to develop criteria for evaluating the validity of radiocarbon dates on lake sediment from basins in calcareous terrain radiocarbon dates from a site in alberta show a variable hard water effect related to local hydrological changes during postglacial history of the lake basin whereas radiocarbon dates from the other site in ontario show no noticeable influence of old carbon during its history these differences are mainly related to lake water residence time which has influenced carbon isotopic exchange between atmospheric co2 and dissolved inorganic carbon in lake water 13c values for bulk organic sediment and terrestrial and aquatic macrofossils reveal that the main component of lake sediment at both sites is autocthonous in origin furthermore each site supported different submerged aquatic plant communities that used different sources of carbon for photosynthesis thereby imprinting the organic sediments with a characteristic 13c composition both sites reflect a clear relationship between 13c values and paleoproductivity this study shows the individualistic response of the developing lake system to the hydrology lake biota and local geology and demonstrates the problem of using 13c in lake sediments as a single criterion to recognize the validity of radiocarbon dates of lake sediment without supporting paleoecological information

carbon isotope ratio of cenozoic co2 a comparative evaluation of available geochemical proxies 1 the carbon isotope ratio 13c of plant material is commonly used to reconstruct the relative distribution of c3 and c4 plants in ancient ecosystems however such estimates depend on the 13c of atmospheric co2 13cco2 at the time which likely varied throughout earth history for this study we use benthic and planktonic 13c and 18o records to reconstruct a long term record of cenozoic 13cco2 confidence intervals for 13cco2 values are assigned after careful consideration of equilibrium and non equilibrium isotope effects and processes as well as resolution of the data we find that benthic foraminifera better constrain 13cco2 compared to planktonic foraminiferal records which are influenced by photosymbiotes depth of production seasonal variability and preservation furthermore sensitivity analyses designed to quantify the effects of temperature uncertainty and diagenesis on benthic foraminifera 13c and 18o values indicate that these factors act to offset one another our reconstruction suggests that cenozoic 13cco2 averaged 6 1 0 6 1 while only 11 2 million of the last 65 5 million years correspond to the pre industrial value of 6 5 with 90 confidence here 13cco2 also displays significant variations throughout the record at times departing from the pre industrial value by more than 2 thus the observed variability in 13cco2 should be considered in isotopic reconstructions of ancient terrestrial plant ecosystems especially during the late and middle miocene times of presumed c4 grassland expansion

patterns and average rates of late neogene recent uplift of the betic cordillera se spain abstract the facies distribution in the sedimentary units infilling a series of neogene basins has been used to reconstruct the relief generation and uplift across the internal zone of the betic cordillera in southern spain uplift amounts and average rates can be estimated using the current elevation of the outcrops of well dated deposits indicative of ancient sea level positions coral reefs and coastal conglomerates record the initial development of emergent betic relief during the langhian continental and marginal marine deposits indicate the existence of a large island centred on the present sierra nevada sierra de los filabres chain by the end of the middle miocene the precursor of the sierra nevada sierra de los filabres chain originally part of this large island remained emerged whilst the surrounding areas were re invaded by the sea during the early tortonian at the end of the tortonian the inland basins granada and guadix basins became continental while the sierras de la contraviesa sierra de gador and sierra alhamilla emerged separating the alboran basin from the alpujarra tabernas and sorbas basins which became narrow passages of the mediterranean sea in contrast the sierra cabrera emerged during the late messinian suggesting a progressive uplift from west to east of the sierras south of the sierra nevada sierra de los filabres chain during the pliocene only the low areas closest to the present day coast remained as marine basins and progressively emerged throughout this stage the highest average uplift rate recorded is 280 m ma for the sierra de gador although the average uplift rates of upper neogene coastal marine rocks since depositon have maximum values of approximately 200 m ma most of the uplift of the betic mountains took place before the early pliocene the recorded uplift of neogene rocks was highest at the margins of western sierra nevada where peaks higher than 3000 m occur the average rates of uplift were lower to the east of this major relief the main sierras and depressions in the present day landscape correspond respectively to the emergent land in which uplift was concentrated and to the marine basins that existed before the final emergence of the region the altitude of the sierras reflects the time at which they became emergent the highest mountains being the first to rise above sea level

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

paleogene paleoclimate reconstruction using oxygen isotopes from land and freshwater organisms the use of multiple paleoproxies abstract understanding past climate change is critical to the interpretation of earth history even though relative temperature change has been readily assessed in the marine record it has been more difficult in the terrestrial record due to restricted taxonomic distribution and isotopic fractionation this problem could be overcome by the use of multiple paleoproxies therefore the 18o isotopic composition of five paleoproxies rodent tooth enamel 18ophosphate 17 7 2 0 n 74 vsmow fish scale ganoine 18ophosphate 19 7 0 7 n 20 vsmow gastropod shell 18ocalcite 1 7 1 3 n 50 vpdb charophyte gyrogonite 18ocalcite 2 4 0 5 n 20 vpdb fish otolith 18oaragonite 18o 3 6 0 6 n 20 vpdb from the late eocene priabonian osborne member headon hill formation solent group hampshire basin uk were determined because diagenetic alteration was shown to be minimal the phosphate oxygen component of rodent tooth enamel as opposed to enamel carbonate oxygen was used to calculate an initial 18olocal water value of 0 0 3 4 however a skewed distribution most likely as a result of the ingestion of evaporating water necessitated the calculation of a corrected 18olocal water value of 1 3 1 7 n 62 this 18olocal water value corresponds to an approximate mean annual temperature of 18 1 c four other mean paleotemperatures can also be calculated by combining the 18olocal water value with four independent freshwater paleoproxies the calculated paleotemperature using the fish scale thermometry equations most likely represents the mean temperature 21 2 c of the entire length of the growing season this should be concordant with the paleotemperature calculated using the lymnaea shell thermometry equation 23 2 c the lack of concordance is interpreted to be the result of diagenetic alteration of the originally aragonitic lymnaea shell to calcite the mean paleotemperature calculated using the charophyte gyrogonite thermometry equation 21 2 c on the other hand most likely represents the mean temperature of a single month toward the end of the growing season the fish otolith mean paleotemperature 28 2 c most likely represents the mean temperature of the warmest months of the growing season an approximate mean annual temperature of 18 1 c in addition to a mean growing season paleotemperature of 21 2 c using fish scale only with a warmest month temperature of 28 2 c and high associated standard deviations suggest that a subtropical to warm temperate seasonal climate existed during the deposition of the late eocene osborne member

cenozoic long term terrestrial climatic evolution in germany tracked by δ18o of rodent tooth phosphate even though the cenozoic has been recognized as a period of important climate change long term climatic changes that took place in the continental domain are still questioned for an area southern germany for which other long term palaeoclimatic records exist analysis of oxygen isotope composition of small mammal teeth has been carried out for localities ranging in age from the late eocene c 36 ma to the middle miocene c 10 ma comparison of this long term continental 18o record with the marine record reveals comparable trends the major cenozoic climatic events are thus recognized in the continental oxygen isotope record through comparison with other quantitative palaeoclimatic reconstructions available for the studied area temperatures in southern germany are broadly estimated to have fluctuated between 12 c and 25 c from late eocene to early late miocene according to the different available chronological frameworks either a 2 c considering the classical biostratigraphy or a 6 c considering a revised biostratigraphy decrease in mean air temperature is estimated for the eocene oligocene boundary

patagonian origin of glacial dust deposited in east antarctica vostok and dome c during glacial stages 2 4 and 6 abstract the source area of continental dust deposited at both vostok and dome c sites east antarctica during the glacial stages stage 2 18 ka last glacial maximum stage 4 60 ka and stage 6 160 ka of the last two climatic cycles has remained constant the isotopic composition 87 sr 86 sr and 143 nd 144 nd of the ice core dust has been compared with the isotopic composition of the potential source areas antarctica new zealand southern africa australia and south america this comparison reveals the southern south american provenance of the dust for all three glacial periods as has already been shown for the lgm 1 we show that the patagonian loess and the marine shelf sediments from the argentine continental shelf which was variably emerged during glacial periods display different isotopic compositions and that the composition of the patagonian loess best matches the signature of the ice core dust the identification of the patagonian region as the source of the windblown dust deposited over east antarctica during all the latest glacial periods permits a better understanding of paleo atmospheric circulations of the last climatic cycles and a better constraint on the parametrization of dust sources for paleoatmospheric general circulation models

rodent palaeoecology of the continental upper miocene of crevillente alicante se spain abstract the upper miocene succession of crevillente presents an alternation of continental and marine beds the marine fossils have been studied in order to obtain a reliable correlation with other marine sections on the basis of these data the entire section can be dated as upper tortonian messinian the alternation of continental and marine beds fits the known eustatic sea level and climatic curves these correlations are used to assign ecological preferences to the components of the micromammal faunas at species level it becomes clear that working at the genus level does not provide valid results with the assignments it is possible to demonstrate consistent climatic differences between the coastal plain of crevillente and the area of teruel on the meseta of central spain

early middle miocene stratigraphic turning points in the alicante region se spain reflections of western mediterranean plate tectonic reorganizations abstract the paper concerns the miocene deposits of the alicante region se spain which forms part of the prebetic and intermediate units representing the former southern passive margin of the iberian continent from the late jurassic up to the miocene the alicante region was the scene of a facies distribution with more continental lagoonal or shallow marine conditions in the north and northwest and more open or deeper marine in the south and southeast the early middle miocene deposits can be divided in three sedimentary cycles each one controlled by a different tectonic regime cycle i aquitanian is deposits after a block faulting phase at about 25 ma related to the formation of the ligurian and balearic troughs cycle ii burdigalian early langhian is separated from first cycle sediments by a complete reorientation of palaeogeography at 19 5 ma due to the collision of iberia with africa the southern part of the region is folded and uplifted and separated from a northern emerged area by a trough cycle iii late langhian serravallian is controlled by strike slip movements caused by the continuing convergence between africa and europe and resulting in the development of a new set of basins at 15 5 ma at the middle late miocene boundary the alicante region emerges thus younger important tectonics could not be dated our results are in conflict with several recent plate tectonic models for the miocene history of the western mediterranean where the internal betic zone is placed juxtaposed to the alicante region prior to the burdigalian

the preservation of glacial interglacial climatic signatures in the oxygen isotopes of elephant skeletal phosphate abstract phosphate 18o values 18op of modern elephant bone and teeth are found to vary linearly according to the 18o of local meteoric water 18omw a parameter with close ties to regional and local climatic conditions enamel dentine cementum and bone separates from individual fossil elephant specimens of late pleistocene age have op values which vary by up to elephant specimens the larger spread in the 18op values of the various skeletal phases for the fossil samples is interpreted as evidence for post depositional alterantion of primary 18op signatures of some if not all of these fossil skeletal components in the fossil samples investigated enamel and dentine phases have systematically lower 18o values than associated bone and cementum phases differential re equilibration with soil waters either by the wholesale replacement of primary apatite or by processes of isotopic exchange is suggested as a mechanism to account for the observed spread in the fossil phosphate 18o data

on the temperature correlation of δ18o in modern precipitation reevaluation of modern precipitation temperature and isotope data permits reconciliation of previous disparate values for the correlation between 18o of modern precipitation and surface temperature past analysis has used the mean surface temperature over the time interval of sample collection e g mean weekly monthly or annual temperature to calculate temperature coefficients and different approaches at mid latitudes yield different temperature coefficients 18o t spatial correlations among geographically distinct sites yield 0 55 k seasonal variations at single sites yield 0 2 0 4 k and 12 month running averages yield 0 5 1 k however there are systematic differences in temperature during precipitation events vs time averaged surface temperature means correction for this bias using hourly weather and monthly isotope data from u s sites yields a single value of 0 55 k for all three approaches revised temperature coefficients based on surface observations are also commensurate with coefficients obtained using cloud base temperatures and with theoretical distillation models 0 5 0 7 k these coefficients provide a consistent basis for validation of general circulation models that incorporate stable isotopes of precipitation and for comparison to independent estimators of the isotopic response to climate change

mammalian faunas as indicators of environmental and climatic changes in spain during the pliocene quaternary transition abstract the study of mammal communities provides useful knowledge of paleoenvironments and paleoclimates during the quaternary period and better documentation about the main fossil sites is making this task easier paleoecological reconstructions of this study are based on i rodent evolution and species richness ii the cenogram method and iii methods for quantifying climatic parameters these analyses applied to a pliocene quaternary faunal sequence of spain indicate that a climatic change occurred at the end of the pliocene when considerable cooling led to the onset of the glacial interglacial cycles subsequently during the quaternary period alternating environmental patterns occurred with a rather open and arid environment during the cold phases that contrasts with a somewhat more closed and comparatively wet environment during warmer phases these observations are generalized from spain to the remainder of the continent noting that climatic conditions were less harsh and more arid in spain than elsewhere in europe