anhydrous partial melting of an iron rich mantle ii primary melt compositions at 15 kbar primary melt and coexisting mineral compositions at increasing degrees of partial melting at 15 kbar were determined for an iron rich martian mantle composition dw the composition of primary melts near the solidus was determined with basalt peridotite sandwich experiments in order to evaluate the approach of the liquids to equilibrium with a dw mantle assemblage experiments were also performed to establish the liquidus mineralogy of the primary melts primary melt compositions produced from an iron rich mantle are more picritic than those produced from an iron poor mantle by increasing the iron content of a model mantle composition decreasing the mg where mg atomic mg mg fe2 100 picritic and komatiitic magmas result at lower percentages of melting and at temperatures closer to the solidus than in an iron poor mantle terrestrial iron rich primitive volcanics may be the partial melting products of iron rich mg 80 source regions the dw partial melting results support the conclusion of previous authors that the parent magmas of the snc shergottites nakhlites chassignites meteorites were derived from a source region that had been previously depleted in an aluminous phase

an interdisciplinary study of a mammoth bearing late pleistocene sediment succession in lower austria abstract in the alpine foreland and the vienna basin loess paleosol sequences lps are common some of the most famous lps sites in the circum alpine area include stratzing gottweig willendorf krems wachtberg and stillfried which cluster in a relatively small area along the danube river in lower austria lps provide detailed insights into climate driven terrestrial palaeoenvironmental changes that can be placed into a robust chronological framework because lps are amenable to a range of dating techniques here we present a well dated 13 6 m thick mammoth bearing sediment succession characterised by low energy aquatic deposits sheet flow deposits and sandy loess from re deposited miocene sediments i e a depositional environment that contrasts to the classical lps sites this new site is situated 1 6 km nne of bullendorf in lower austria where pleistocene sediment successions with a robust chronology are rare our multidisciplinary approach is based on optically stimulated luminescence and 14c dating and includes mammal faunal investigations and stable isotope analyses of molluscs osl and 14c dating suggest deposition of the sediment sequence immediately before and briefly after the last glacial maximum the mollusc assemblages and the mammal fauna are representative of a cold climate characteristic of a tundra steppe environment stratigraphic changes in 18o of two mollusc species pupilla muscorum and succinella oblonga suggest an alternating dry cold and humid cold climate oxygen isotope data of freshwater gastropod shells suggest a drastic decrease in the mean growing season temperature compared to today while the carbon isotope composition is indicative of a c3 vegetation

quaternary interglacial environmental stability in san salvador island bahamas a land snail isotopic approach abstract the 13c 12c and 18o 16o ratios of modern and fossil shells of two ecologically distinct land snail taxa cerionidae and annularidae from san salvador island were analyzed to estimate the interglacial pleistocene and holocene paleoenvironmental conditions in the bahamas the average 13c value of cerion was 5 0 1 8 for modern 0 0 1 ka specimens 4 3 0 7 for late holocene 2 4 6 ka individuals 3 4 1 6 for middle holocene 5 6 3 ka shells 4 0 1 5 for 85 or 110 ka specimens and 3 6 0 4 for individuals that grew during ois 5e 125 ka annularidae specimens displayed average 13c values of 6 3 2 5 6 1 1 0 2 4 1 0 4 4 1 1 and 5 0 2 9 respectively these results suggest that snails consumed c3 and c4 plants arbitrarily through time however higher proportion of c4 plants may have been consumed in the past compared to the present cerion was 1 higher in average 13c value than annularidae specimens for some time intervals indicating greater c4 plant consumption and or higher ingestion of carbonate rich sediments the average 18o value of cerion was 0 5 0 8 for modern individuals 0 5 0 5 for late holocene specimens 0 8 0 2 for middle holocene shells 0 4 0 6 for 85 or 110 ka specimens and 0 3 0 6 for ois 5e individuals annularidae individuals exhibited average 18o values of 0 7 0 8 0 5 0 9 0 9 0 3 0 3 0 6 and 0 9 0 9 respectively these results point to similar atmospheric conditions over time intervals when shell was deposited the shell 18o values did not significantly differ between species despite the apparent differences in lifestyle calculations from a snail evaporative steady state flux balance model and proxy data suggest that modern individuals deposited shell at air temperatures of 24 25 c ambient water 18o values between 4 5 and 3 5 smow and relative humidity of 87 89 late to middle holocene and interglacial late pleistocene shells appear to have precipitated under a similar environmental setting overall atmospheric conditions during these quaternary interglacial time intervals at coastal sites of san salvador were largely comparable to the present this apparent environmental similarity is consistent with the relatively comparable snail richness and diversity observed at those same locales and time intervals

stable isotope composition of late pleistocene holocene eobania vermiculata muller 1774 pulmonata stylommatophora shells from the central mediterranean basin data from grotta d oriente favignana sicily abstract this paper presents stable isotopic results oxygen and carbon from both modern and late pleistocene holocene shells of the land snail eobania vermiculata muller 1774 from favignana island sicily it aims to contribute to the understanding of climate and vegetation history of this region during formation of upper palaeolithic mesolithic and meso neolithic deposits of grotta d oriente ort results from both an evaporative model fbm and an empirical regional isotopic model i e linear relation between oxygen isotopic composition of shells 18 os and those of local precipitation 18 op indicate that the 18 os values of modern specimens are mainly controlled by local temperature relative humidity and 18 op at the time of snail activity data also suggest that the modern snails are nocturnally active almost all year round in the study area the carbon isotopic compositions of shells 13 cs of the same specimens indicate a diet prevalently or exclusively composed of c3 vegetation the 18 os values of late pleistocene specimens suggest that climate conditions at 14 2 ka cal bp were similar to the present day in agreement with additional 18 os records from southern italy by contrast early middle holocene shells are notably 18 o depleted and suggest wetter conditions possibly combined with a decrease in isotopic composition of precipitation source compared to the present day when compared with regional palaeoclimatic records a large scale isotopic response to millennial scale changes in atmospheric and hydrological conditions e g enhanced rainfall in the central eastern mediterranean is observed during the early middle holocene the 13 cs of late pleistocene and holocene specimens are consistently higher than those of modern ones for the late pleistocene this could be reasonably explained in terms of water stressed vegetation on the other hand this seems to be less valid for holocene counterparts when the climate was wetter probably 13 cs values result from the combination of distinct competing factors involving atmospheric co 2 concentration seasonal water budget vegetation type cover and other carbon sources results reveal coherent relationships between regional 18 os and 13 cs demonstrating that late pleistocene holocene land snail shell remains from archaeological sites may provide useful snapshots of past seasonal climate conditions

crystallization experiments on a gusev adirondack basalt composition until recently the snc meteorites represented the only source of information about the chemistry and petrology of the martian surface and mantle the mars exploration rovers have now analyzed rocks on the martian surface giving additional insight into the petrology and geochemistry of the planet the adirondack basalts analyzed by the mer spirit in gusev crater are olivine phyric basaltic rocks which have been suggested to represent liquids and might therefore provide new insights into the chemistry of the martian mantle experiments have been conducted on a synthetic humphrey composition at upper mantle and crustal conditions to investigate whether this composition might represent a primary mantle derived melt the humphrey composition is multiply saturated at 12 5 kbar and 1375 c with olivine and pigeonite a primary anhydrous melt derived from a chondritic mantle would be expected to be saturated in orthopyroxene not pigeonite in addition the olivine and pigeonite present at the multiple saturation are too ferroan to have been from a martian mantle as is understood now therefore it seems likely that the humphrey composition does not represent a primary anhydrous melt from the martian mantle but was affected by mineral melt fractionations at lower crustal pressures

the influence of diet on the δ13c of shell carbon in the pulmonate snail helix aspersa abstract the influence of diet and atmospheric co2 on the carbon isotope composition of shell aragonite and shell bound organic carbon in the pulmonate snail helix aspersa raised in the laboratory was investigated three separate groups of snails were raised on romaine lettuce c3 plant 13c 25 8 corn c4 plant 13c 10 5 and sour orange 12c enriched c3 plant 13c 39 1 the isotopic composition of body tissues closely tracked the isotopic composition of the snail diet as demonstrated previously however the isotopic composition of the acid insoluble organic matrix extracted from the aragonite shells does not track diet in all groups in snails that were fed corn the isotopic composition of the organic matrix was more negative than the body by as much as 5 whereas the matrix was approximately 1 heavier than the body tissues in snails fed a diet of c3 plant material these results indicate that isotopic composition of the organic matrix carbon cannot be used as an isotopic substrate for paleodietary reconstructions without first determining the source of the carbon and any associated fractionations the isotopic composition of the shell aragonite is offset from the body tissues by 12 3 in each of the culture groups this offset was not influenced by the consumption of carbonate and is not attributable to the diffusion of atmospheric co2 into the hemolymph the carbon isotopic composition of shell aragonite is best explained in terms of equilibrium fractionations associated with exchange between metabolic co2 and hco3 in the hemolymph and the fractionation associated with carbonate precipitation these results differ from previous studies based primarily on samples collected in the field that have suggested atmospheric carbon dioxide contributes significantly to the shell 13c the culture results indicate that the 13c of aragonite is a good recorder of the isotopic composition of the snail body tissue and therefore a better recorder of diet than is the insoluble shell organic carbon because the systematic fractionation of carbon isotopes within the snail is temperature dependent the 13c of the shell could provide an independent technique for estimating paleotemperature changes

oxygen isotope signatures from land snail helix melanostoma shells and body fluid proxies for reconstructing mediterranean and north african rainfall abstract in this paper we show that oxygen isotope ratios from the shell carbonate of the land snail helix melanostoma reflect local rainfall parameters stable oxygen isotopes were measured in the body fluid 18 o body and shells 18 o shell of live collected h melanostoma along a north south transect across the gebel akhdar in northeast libya 18 o body ranged between 8 1 and 13 0 whilst 18 o shell ranged between 1 0 and 2 8 to investigate the relationship between snail oxygen isotope composition and climate these measurements were correlated with ambient air temperature relative humidity rainfall amount and the 18 o composition of rainwater 18 o rain strong and significant correlations were found between 18 o shell and 18 o rain and between 18 o shell and rainfall amount r 2 0 79 and 0 85 respectively suggesting that h melanostoma shells can be used as a proxy for past rainfall conditions when combined in multiple linear regressions 18 o rain and rainfall amount explained 90 of the variance in 18 o shell r 2 0 90 simple and multiple linear regressions were used to develop predictive models for these climate parameters as h melanostoma shells are commonly found in mediterranean and north african archaeological and geological deposits the predictive equations developed in this study hold great potential for reconstructing pleistocene to holocene rainfall and aridity patterns in the gebel akhdar and for assessing the relationship between environmental changes and human behavioural changes

overview of the oxygen isotope systematics of land snails from north america continental paleoclimate proxies with near global coverage are rare land snail 18o is one of the few proxies abundant in quaternary sediments ranging from the tropics to the high arctic tundra however its application in paleoclimatology remains difficult attributable in part to limitations in published calibration studies here we present shell 18o of modern small 10 mm snails across north america from florida 30 n to manitoba 58 n to examine the main climatic controls on shell 18o at a coarse scale this transect is augmented by published 18o values which expand our coverage from jamaica 18 n to alaska 64 n results indicate that shell 18o primarily tracks the average annual precipitation 18o shell 18o increases 0 5 0 7 for every 1 increase in precipitation 18o and 0 3 0 7 for every 1 c increase in temperature these relationships hold true when all taxa are included regardless of body size ranging from 1 6 to 58 mm ecology herbivores omnivores and carnivores or behavior variable seasonal active periods and mobility habits future isotopic investigations should include calibration studies in tropical and high latitude settings arid environments and along altitudinal gradients to test if the near linear relationship between shell and meteoric precipitation 18o observed on a continental scale remains significant

calibration of the stable isotope composition and body size of the arid dwelling land snail sphincterochila candidissima a climatic archive abundant in mediterranean archaeological deposits land snails recovered from archeological deposits may be used to deduce climatic conditions during prehistoric occupation because their aragonitic skeletons are usually well preserved and document valuable climatic information in the form of isotope codes since the snail sphincterochila candidissima is common in archeological sites along the western mediterranean but has been minimally investigated the present work examines the relationship between the oxygen 18o and carbon 13c stable isotopes of modern specimens and relevant meteorological data individuals of sphincterochila were regularly live collected throughout 1 year from september 2013 to october 2014 in tarragona ne spain and the 18o and 13c values were measured at the shell lip or aperture which depicts the last growth episode closest to specimens collection date shell margin 18o values varied from 3 1 in september to 0 8 in april average shell margin 18o values per collection date positively correlated with monthly avera

succession and stable isotope composition of gastropods in holocene semi arid alluvial sequences bardenas reales ebro basin ne spain palaeoenvironmental implications three alluvial units ranging from the middle to late holocene in age were distinguished in bardenas reales natural park ebro basin ne spain based on morphosedimentary analysis and radiocarbon data in this sensitive mediterranean alluvial system the succession and isotopic composition of gastropods greatly contribute to establishing the prevailing palaeoenvironmental conditions the oldest unit 4763 87 to 2848 55 cal yr bp represents fluvial channels and swamped areas includes the greatest proportion of aquatic gastropods ancylus fluviatilis and lymnaea truncatula and marsh species vallonia pulchella and presents the most negative values of 18o mean 2 21 pdb the intermediate unit 1403 60 to 836 65 cal yr bp shows a high rate of alluvial activity related to irregular torrential rainfall with sedimentary features of aridity and this unit includes only dry open ground gastropods xeroplexa sp chondrinidae indet and granopupa granum and presents the least negative values of 18o

late glacial to holocene transition in northern spain deduced from land snail shelly accumulations abstract shells of the helicid cepaea nemoralis were studied using taphonomic isotopic and morphometric measurements to estimate late glacial holocene 12 1 6 3 cal ka bp environmental conditions in northern spain higher taphonomic alteration among holocene shells suggests lower sedimentation rates or higher shell destruction rates than during glacial conditions shells preserved the aragonitic composition despite differing degree of skeleton damage shell 13 c values were 10 3 1 1 8 2 2 3 and 7 3 1 6 for modern holocene and late glacial individuals respectively higher 13 c values during the late glacial and some holocene periods imply higher water stress of c 3 plants and or higher limestone contribution than today intrashell 13 c values were higher during juvenile stages suggesting higher limestone ingestion to promote shell growth shell 18 o values were 1 1 0 7 0 9 0 8 and 0 1 0 7 for modern holocene and late glacial specimens respectively a snail flux balance model suggests that during 12 1 10 9 cal ka bp conditions were drier and became wetter at 8 4 6 3 cal ka bp and today intrashell 18 o profiles reveal that glacial individuals experienced more extreme seasonality than interglacial shells despite possible larger hibernation periods shell size correlated positively with 18 o values suggesting that growth rates and ultimate adult size of c nemoralis may respond to climate fluctuation in northern spain

stable isotope δ18o δ13c and δd signatures of recent terrestrial communities from a low latitude oceanic setting endemic land snails plants rain and carbonate sediments from the eastern canary islands abstract stable isotopes of oxygen and carbon extracted from fossil land snail shells have been used increasingly to interpret past environments to evaluate the utility of this approach for low latitude oceanic islands populations of the modern helicid land snail theba geminata a species also abundant in the quaternary fossil record of the region were sampled at ten low altitude d and 2 v smow for 18 o ranging from 11 to 2 v smow and from 2 6 to 0 7 v smow respectively the local vegetation is heterogeneous including c 3 c 4 and cam plants 13 c values vary from 13 0 to 29 0 v pdb across plant species of the 24 species five are c 4 15 are c 3 and four are cam plants the 18 o values for shells represent a narrow range of values from 0 3 to 2 5 v pdb which is consistent with the low climate seasonality typifying low latitude oceanic settings hypothetical model of the expected 18 o value for shell aragonite precipitated in equilibrium suggests that the most negative 18 o shell represent the closest estimate for 18 o rain water the 13 c values of shells range from 9 4 to 1 7 v pdb the most positive 13 c values are attributed to a diet based on c 4 plants the comparison of 13 c values of soft tissues and shells suggests that snails ingested notable amounts from 20 up to 40 of foreign carbonates consequently fossil shells with the most negative 13 c values should be selected for radiocarbon dating in future geochronological studies of the region the 13 c values of body tissues vary from 12 0 to 27 2 v pdb indicating that land snails consumed c 3 and c 4 plants indiscriminately the mean carbon isotopic composition averaged across multiple fossil specimens may thus provide a useful tool for reconstructing paleoclimates and paleoenvironments throughout the quaternary history of the canary islands and other comparable low latitude oceanic settings

the use of land snail shells in paleoenvironmental reconstruction fossil land snail shells constitute a valuable source of paleoenvironmental information for the quaternary they can be dated by a variety of methods including radiocarbon amino acid racemization and epimerization and perhaps also thu and esr the vast majority of paleoenvironmental studies based on land snail shells have examined the faunal composition of fossil assemblages from which a variety of paleoenvironmental characteristics such as biome temperature and moisture conditions have been reconstructed still there are a number of problems involved in using this approach and these are discussed shell morphology has occasionally been used to reconstruct such factors as rainfall and temperature stable isotope studies on quaternary land snails include analysis of 18o values of organic matter in the shells to reconstruct c4 plant distributions from which rainfall amounts can be inferred and analysis of 18o values of shell carbonate from which trends in the oxygen isotope composition of rainfall can be reconstructed stable carbon isotopes of shell carbonate have also been studied but their interpretation is not clear amino acid epimerization analysis dalloisoleucinel isoleucine ratios of land snail shells has been used for estimation of paleotemperatures some potential uses of land snail shells for paleoenvironmental reconstruction include the study of stable isotopes of h and n periodic growth lines and deposits of pedogenic carbonates on the shells

late pleistocene holocene environmental conditions in lanzarote canary islands inferred from calcitic and aragonitic land snail shells and bird bones aragonitic and calcitic land snails from carbonate rich paleosols in northwestern lanzarote canary islands were analyzed for 13c 12c and 18o 16o ratios to deduce the pleistocene holocene transition in the westernmost sahara zone modern mid late holocene 2 1 5 5 cal ka bp and late pleistocene 23 3 24 0 cal ka bp aragonitic shells exhibited respective values of 9 5 1 6 7 7 1 5 and 2 3 2 8 for 13c and 0 3 0 3 0 1 0 7 and 2 5 0 4 for 18o holocene and pleistocene calcitic shells of the endemic slug cryptella canariensis showed respective values of 0 7 2 6 and 8 5 2 5 for 13c and 0 8 1 5 and 3 6 0 4 for 18o both aragonitic and calcitic shells showed equivalent temporal isotopic trends higher 13c values during 23 3 24 0 cal ka bp suggest higher abundance of c4 and or cam plants likely associated with drier conditions and or lower atmospheric co2 concentration maximum shell 18o values during 23 3 24 0 cal ka bp opposes minimal values of greenland ice cores and probably reflect the combined effects of 1 higher rain 18o values linked to higher glacial seawater 18o values and or larger snail activity during summer seasons 2 relative humidity values similar or slightly lower than at present 3 higher evaporation rates and 4 cooler temperatures bone remains of the extinct dune shearwater puffinus holeae were only recovered from the holocene bed collagen 13c and 15n values 13 5 0 2 pdb and 13 7 1 0 air respectively match with the signature of a low trophic level macaronesian seabird that fed upon local fish bone carbonate 13c 7 4 1 0 pdb and phosphate 18o 18 2 0 4 smow values exhibited pristine signals denoting their potential value in future paleoenvironmental studies in the region the age of p holeae 2 1 2 7 cal ka bp supports that the aboriginal population possibly caused its extinction in contrast the extinction of the endemic helicid theba sp 23 3 24 0 cal ka bp was likely caused by environmental change

study of the diet effect on δ13c of shell carbonate of the land snail helix aspersa in experimental conditions abstract this study aims to demonstrate the influence of the metabolic co2 derived from the diet and of the atmospheric co2 on the shell carbonate 13c of the pulmonate snail helix aspersa maxima raised under controlled conditions adult snails were analyzed and compared with three hatching and 1 day old young snails stemming from the same breeding one day after the 2 day old individuals were raised during 1 month three groups of gastropods were fed with fresh lettuce c3 plant 13c 27 49 three groups with corn c4 plant 13c 11 7 and three groups ate alternately both c3 c4 the difference between the average 13c values of the adult snails on the one hand and the hatched and 1 day old snails on the other hand indicates a depletion of 2 47 therefore the isotopic parents offspring signal is not preserved the depleted ingested albumen by the snail embryo in the egg during the building of the shell could explain this depletion the c3 diet experiment gave the expected isotopic composition difference between the diet lettuce and the shells average 13cshell lettuce 13 75 0 52 this result shows a clear diet effect on the isotopic composition of the snail shells for the c4 experiment the difference in carbon isotope composition between the corn and the shell 13cshell corn yielded an average value of 4 89 0 87 the main result is that 13c is not constant and appears to depend on the type of ingested food several hypotheses can arise from this study to explain the different fractionations a differences in the quality of the two diets b differences in turnover rate for c3 and c4 feeders the groups regularly fed with mixed diet yielded 13c values showing a preferential use of c3 food for most values the c3 c4 mixed dietary alternation probably led snails to use mainly the lettuce instead of the corn powder

middle pleistocene mis 14 environmental conditions in the central mediterranean derived from terrestrial molluscs and carbonate stable isotopes from sulmona basin italy abstract a paleosol from the middle pleistocene lacustrine fluvial succession of sulmona basin central italy was analysed for the land snail shell content and the stable isotope composition of the shells and associated pedogenic carbonates the paleosol known as fiorata paleosol is covered by a thick tephra layer dated to ca 527 ka allowing the pedogenetic horizons to be correlated to the marine isotope stage mis 14 early mis 13 interval the terrestrial mollusc assemblage contained few individuals and was characterized by a low number of species which predominantly indicate open and dry habitats thus suggesting that fiorata paleosol likely developed during glacial conditions of the mis 14 the 13 c values of pedogenic carbonates and terrestrial shells indicate prevailing c 3 type vegetation probably marked by some degree of water stress calculation of the 18 o precipitation values derived from pedogenic carbonates and shell 18 o values indicate that the average temperature was 3 5 c lower than present day this study highlights how paleosols despite offering only snapshots of past climate and environments provide valuable complementary information to paleoclimatic data obtained in the adjacent lacustrine intervals specifically for the sulmona successions

coupled european and greenland last glacial dust activity driven by north atlantic climate centennial scale mineral dust peaks in last glacial greenland ice cores match the timing of lowest greenland temperatures yet little is known of equivalent changes in dust emitting regions limiti

carbon isotope signatures from land snail shells implications for palaeovegetation reconstruction in the eastern mediterranean in this study we compare carbon isotope values in modern helix melanostoma shell carbonate 13cshell from the gebel al akhdar region of libya with carbon isotope values in h melanostoma body tissue 13cbody local vegetation 13cplant and soil 13csoil all vegetation in the study area followed the c3 photosynthetic pathway however the 13cplant values of different species formed two distinct isotopic groups this can be best explained by different water use efficiencies with arid adapted species having significantly more positive 13cplant values than less water efficient species the ranges and means of 13cbody and 13cplant were statistically indistinguishable from one another suggesting that 13cbody was primarily a function of local vegetation composition h melanostoma 13cshell reflected the 13cplant of local vegetation with a positive offset between body diet and shell of 14 5 1 4 therefore in the gebel al akhdar where only c3 plants are present higher mean 13cshell values likely reflect greater abundances of water efficient c3 plants in the snails diet and therefore in the landscape whilst lower mean 13cshell values likely reflect the consumption of less water efficient c3 plants the distribution of these plants is in turn affected by environmental factors such as rainfall these findings can be applied to archaeological and geological shell deposits to reconstruct late pleistocene to holocene vegetation change in the southeast mediterranean

oxygen isotope composition of living land snail shells data from italy sixty seven shells of living land snails were selected from 31 different localities across italy to investigate the relationships between their oxygen isotopic composition 18os and the mean value of local rainfall 18op despite the difficulty for some localities to correctly estimate the oxygen isotopic composition of local rainfall a good relationship was found this indicates that the oxygen isotopic composition of environmental water used by the snails is in italy strictly related to that of the local meteoric precipitation however the relationship found is substantially different from that previous established for central europe indicating that regional climatic conditions are important in defining the final isotopic composition of land snail shells moreover these equations may not hold for different climatic conditions existing during for instance glacial and interglacial periods the data also show that isotopic differences among species are relatively narrow and that they may depend on ecological factors i e style of life rather than any clearly identifiable different vital offset

alpha particle x ray spectrometer apxs results from gusev crater and calibration report 1 the chemical composition of rocks and soils on mars analyzed during the mars exploration rover spirit mission was determined by x ray analyses with the alpha particle x ray spectrometer apxs details of the data analysis method and the instrument calibration are presented measurements performed on mars to address geometry effects and background contributions are shown cross calibration measurements among several instrument sensors and sources are discussed an unintentional swap of the two flight instruments is evaluated new concentration data acquired during the first 470 sols of rover spirit in gusev crater are presented there are two geological regions the gusev plains and the columbia hills the plains contain soils that are very similar to previous landing sites on mars a meteoritic component in the soil is identified rocks in the plains revealed thin weathering rinds the underlying abraded rock was classified as primitive basalt one of these rocks contained significant br that is probably associated with vein filling material of different composition one of the trenches showed large subsurface enrichments of mg s and br disturbed soils and rocks in the columbia hills revealed different elemental compositions these rocks are significantly weathered and enriched in mobile elements such as p s cl or br even abraded rock surfaces have high br concentrations thus in contrast to the rocks and soils in the gusev plains the columbia hills material shows more significant evidence of ancient aqueous alteration

rainfall in the negev desert during the middle holocene based on 13c of organic matter in land snail shells abstract analysis of stable carbon isotope ratios 13 c 12 c of organic matter in land snail shells is used to infer middle holocene rainfall amounts in the negev desert by reconstructing the distribution of c 4 plants in the family chenopodiaceae the organics are derived from the diet of the snails which consists of plant material and are enriched in 13 c where c 4 plants are present a survey of modern plant communities indicates that in areas receiving 300 mm mean annual rainfall nearly all plant communities consist of c 3 species only no c 4 chenopodes whereas in areas under 230 mm rainfall most plant communities contain one or more c 4 chenopode species in between is a transition zone consisting of a mosaic of both pure c 3 and mixed c 3 c 4 plant communities isotopic results for fossil land snails indicate a consistent geographic pattern throughout the middle holocene from ca 6500 to 3000 yr b p with the transition zone located ca 20 km south of its present position this implies a near doubling of rainfall within this region as compared to present

clumped isotopic signatures in land snail shells revisited possible palaeoenvironmental implications abstract it is crucial to understand the clumped isotope compositions 47 of modern land snail shells and their relationship with environmental parameters for palaeoenvironmental studies previous studies have shown significant variations in relationships between snail shell 47 and ambient air temperature and the reliability of shell 47 in indicating air temperature remains uncertain this study examined the shell 47 from china with mean annual temperatures ranging from 5 to 23 c and the snail body fluid 18o estimated from shell 18o and 47 derived temperatures for all snails studied in this study site averaged 47 values yield snail calcification temperatures ranging from 25 to 36 c which are higher than expected in either environmental temperatures or estimated snail activity temperatures we suggest that snails up regulate their body temperatures towards their preferred living conditions likely through behaviour or and physiology adaptation especially at low temperature environments which is likely significant than observed previously 47 disequilibrium associated with co2 degassing during snail calcification is potential but it could possibly be corrected by using an empirical calibration based on natural land snails varying degrees of 18o enrichment 8 relative to rainwater are observed in snail body fluids possibly due to variable evaporation during shell calcification coupled with model calculations the relationship between snail body fluid 18o and rainwater 18o could be improved by using 47 based temperature and 18o thermometry if snails prefer to be active at 90 relative humidity this study highlights the importance of land snail shell 47 coupled with shell 18o to indicate temperature and rainwater 18o at micro environments scales

environmental conditions framing the first evidence of modern humans at tam pa ling laos a stable isotope record from terrestrial gastropod carbonates abstract mainland southeast asia is a key region to interpret modern human migrations however due to a scarcity of terrestrial proxies environmental conditions are not well understood this study focuses on the tam pa ling cave site in northeast laos which contains the oldest evidence for modern humans in indochina dating back to mis 4 70 8 ka snail remains of camaena massiei found throughout the stratigraphic sequence contain a valuable oxygen and carbon isotope record of past local vegetation and humidity changes our data indicate that before the last glacial maximum lgm northeast laos was characterized by a humid climate and forested environments with the onset of the lgm a major climatic shift occurred inducing a sharp decrease in precipitation and a significant decline in woodland habitats in favor of the expansion to more open landscapes only during the holocene did forests return in northeast laos resembling present conditions the first homo sapiens arriving in indochina therefore encountered landscapes dominated by woodlands with a minor proportion of open habitats

holocene paleoenvironment 7200 4000 cal bp of the los castillejos archaeological site se spain inferred from the stable isotopes of land snail shells abstract neolithic copper age and modern land snail shells from the los castillejos archeological site 37 20 n se iberian peninsula were analyzed for 13 c 12 c and 18 o 16 o ratios to estimate the paleoenvironmental conditions during shell deposition modern and ancient 13 c values ranged from 9 2 to 7 7 and from 13 6 to 5 7 respectively and they differed among taxa 13 c values were similar for neolithic 13 c 8 1 2 3 copper age 13 c 8 4 0 6 and modern 13 c 8 4 0 5 herbivorous cernuella specimens alternatively fossil shells of the herbivorous ferussacia folliculum 13 c 9 9 1 2 and the omnivorous rumina decollata 13 c 11 1 2 showed substantially lower 13 c values than modern specimens which may suggest lower water stress during the early to mid holocene than today the 18 o values from modern specimens ranged from 1 1 to 0 6 while the 18 o values from fossil specimens ranged from 6 7 to 0 and they differed among species cernuella exhibited shell 18 o values that increased from the neolithic 18 o 2 3 1 8 and copper age 18 o 1 7 0 6 to the present 18 o 0 3 0 5 the 18 o values of fossil shells of f folliculum 18 o 3 7 1 0 and r decollata 18 o 4 0 1 6 were also lower than modern shells calculations of a published snail flux balance mixing model for 18 o values indicate that early to mid holocene shells precipitated during times when relative humidity was greater than today the se iberian peninsula was noticeably wetter 7200 cal bp and experienced drier conditions thereafter the results are consistent with other regional paleoclimatic proxies and reinforce the potential use of land snail shells as paleoenvironmental archives

clumped and stable isotopes of land snail shells on the chinese loess plateau and their climatic implications abstract we report stable 13cshell 18oshell and clumped isotope 47 compositions of modern and last glacial fossil snail shell carbonates from the luochuan and weinan sections on the central and southern chinese loess plateau clp our study reveals that the average 47 temperature t47 of modern snails is consistent with monitored temperatures during the snail growing season at the studied locations and is 10 c higher than that of fossil snails from glacial time moreover the average 13cshell of modern snails is more depleted than that of fossils we argue that the 13cshell cannot record changes in plant communities i e the c3 c4 ratio on the clp and may mainly indicate arid conditions with depleted values reflecting reduced aridity additionally the reconstructed snail body water 18o 18owater of modern snails is more enriched than 18o in modern growing season precipitation and 18owater of fossils this contrast may be related to the high degree of evaporative enrichment of environmental water 18o in the body ingested by modern snails under warm conditions therefore we suggest that using 18oshell to directly reconstruct the oxygen isotopes of precipitation is difficult and that higher 18oshell and 18owater values probably indicate higher environmental temperature stronger evaporative enrichment on glacial interglacial timescales on the clp

physical modeling investigation of rainfall infiltration in steep layered volcanoclastic slopes abstract infiltration processes in layered slopes can be strongly affected by the different hydraulic properties of the soils constituting the layers with potential downslope flow diversion that can have effects on slope stability as well as on runoff generation and groundwater recharge in this respect volcanoclastic soil covers represent a typical example as layers with strongly contrasting textures are deposited during the various eruptive phases in this paper the results of a transient infiltration test carried out in a densely instrumented physical model of a layered volcanoclastic sloping cover are presented the soil cover was constituted by a layer of gravelly pumices interbedded between two layers of finer ashes sandy loams even with such an extreme contrast in texture capable of significantly delaying the advancement of infiltration through the layer of pumices flow diversion occurred only temporarily at the interface between the upper layer of ashes and the pumices in fact although a long lasting intense rainfall was applied into an initially dry soil profile the downslope diverted water volume in form of a subsurface runoff was just a small fraction of the total applied rainfall in fact the accumulation of water above the upper edge of the pumices responsible of the subsurface runoff soon led to the establishment of a large water potential gradient which redirected the infiltrating flow through the pumices and stopped the downslope flow diversion

stable isotope composition of late glacial land snail shells from grotta del romito southern italy palaeoclimatic implications abstract stable isotope composition of living and fossil land snail shells was determined at grotta del romito southern italy with the aim to reconstruct environmental and climatic variation in the area during late upper palaeolithic the investigated succession comprised 15 different excavated layers spanning between ca 13 000 and 14 500 yr cal bp the oxygen isotope composition of snail shells indicates a marked decrease at the layer d8 suggesting a climatic deterioration consistent with the gi 1d climatic event older dryas this climate deterioration may have been related to a substantial decrease of mean annual temperature with associated changes in the regional atmospheric circulation however the environmental conditions at the time of shell s growth in the other intervals sampled suggest condition comparable to the present day the carbon isotope composition of fossil snail shells is in agreement with other records which indicate a general increase of the 13 c values of organic matter during pleniglacial to late glacial caused by substantially lower atmospheric co 2 concentration at that time

reconstruction of late pleistocene climate in the valsequillo basin central mexico through isotopic analysis of terrestrial and freshwater snails we aim to reconstruct the climatic and environmental conditions in the valsequillo basin during the deposition of the valsequillo gravels between c 40 000 and 8000 years ago when large mega fauna and potentially humans occupied the basin fossil freshwater fossaria sp and sphaeriidae family and terrestrial polygyra couloni holospira sp and cerionidae family snail shells from sections within the barranca caulapan were collected for oxygen and carbon stable isotope analysis oxygen and carbon isotopes in terrestrial and freshwater snail shells relate to local climatic parameters and environmental conditions prevailing during the lifetime of the snail whole shell isotope analysis showed that c 35 000 years ago climate in the valsequillo basin was similar to the present day between c 35 000 and 20 000 bp conditions became increasingly dry after which conditions became wetter again although this record is truncated intra shell isotopic analyses show that the amount of precipitation varied seasonally during the late pleistocene if people did reach this part of the americas in the late pleistocene they would have experienced changing long term and seasonal climatic conditions and would have had to adapt their life strategies accordingly

alkalic parental magmas for chassignites detailed analysis of cumulate and melt inclusion assemblages in the chassignites provide important constraints on the nature of the melt trapped as inclusions in cumulus olivine and by extension parental magma compositions the pressures of crystallization and magmatic volatile contents these mineral assemblages show strong similarities to the experimental fractionation assemblages that produce the sodic silica saturated alkalic lavas on earth e g ascension island azores the nandewar volcano of australia the experimental assemblages were produced from silica saturated hawaiite at pressures above 4 3 kbar with dissolved water contents above 0 5 wt such pressures are consistent with ti al ratios of the melt inclusion pyroxenes in the chassigny meteorite pyroxene compositions suggest early high crystallization temperatures and thus relatively low initial water and f contents feldspars indicate that melt evolution proceeded to rhyolite compositions both within the interstices of the cumulate olivine and within the melt inclusions even though rhyolitic glass is only found within olivine hosted polyphase melt inclusions the observed rhyolite glass is compositionally similar to the alkali rich rhyolite of ascension island which is produced experimentally by crystallization of hawaiite it is proposed that the melt trapped in cumulus olivine of the chassigny dunite was similar to a terrestrial silica saturated hawaiite while that trapped in olivine of the northwest africa nwa 2727 dunite was less evolved perhaps mildly alkalic basalt melts similar to terrestrial intra plate tholeiite could be parental to the cumulus minerals and evolve upon crystallization at pressures above 4 3 kbar and water contents above 0 4 wt to mildly alkalic basalt silica saturated hawaiite and alkali rich rhyolite the melt inclusion assemblages are inconsistent with either crystallization of a low al high fe basalt or low pressure crystallization of a terrestrial like tholeiite

holocene snail shell isotopic record of millennial scale hydrological conditions in western mediterranean data from bauma del serrat del pont ne iberian peninsula land snail shells are a common component in mediterranean holocene archaeological deposits providing the opportunity to explore their potential as source of information concerning human behaviour and palaeoclimatic conditions many well preserved shells of the caenogastropod pomatias elegans were recovered along the holocene succession of bauma del serrat del pont bsp in the iberian peninsula their oxygen 18os and carbon 13cs isotopic compositions were analysed and compared with that of modern shells of the same species collected in two distinct areas near the archaeological site modern shells from site a shady and b sunny show distinctly different oxygen isotopic ratios possibly due to the effect of microenvironmental conditions e g temperature and relative humidity carbon isotopes by contrast reveal similar values isotope mass balance suggests a prevalent contribution of vegetation 70 integrated with foreign carbonates 30 to 13cs of modern snails early late holocene shells 9 2 5 cal ka bp have lower 18os compared with modern counterparts which is consistent with prevailing wetter conditions compared with present day the 13cs reveals distinct hydrological regimes wet and dry conditions from early to late holocene respectively in general shell isotopic records from western and central mediterranean regions suggest wetter conditions during the middle holocene with a possible reduction in humidity from 4 cal ka bp the 18os indicates a possible latitudinal difference in hydrological balance between mediterranean and atlantic europe as inferred by previous studies of regional palaeoclimatic records carbon isotopes by contrast do not provide a clear climatic picture probably due to the effect of distinct vegetation structure and composition comparisons with other environmental archives reinforce the concept of regional shell oxygen isotopic response to millennial scale changes in hydrological condition over the western and central mediterranean during the late quaternary

paleoenvironment of the folsom archaeological site new mexico usa approximately 10 500 14c yr b p as inferred from the stable isotope composition of fossil land snail shells abstract well preserved aragonitic land snail shells vallonia from late pleistocene eolian sediment in the folsom archaeological site in new mexico exhibit an overall decrease of 18opdb from maximum values of 2 7 more positive than modern to younger samples with lower average values of about 3 6 within the modern range the age of the samples approximately 10 500 14c yr b p suggests that the decrease in 18o may manifest climatic changes associated with the younger dryas some combination of increased relative humidity and cooler temperatures with decreased 18o of precipitation during the times of snail activity can explain the decrease in shell 18o a well known paleoindian bison kill occurred at the folsom site during this inferred environmental transition average 13c values of the aragonite shells of the fossil vallonia range from 7 3 to 6 0 among different archaeological levels and are not as negative as modern values this suggests that the proportion of c4 vegetation at the folsom site approximately 10 500 14c yr b p was greater than at present a result which is consistent with other evidence for higher proportions of c4 plants in the region at that time

implications of the apparent 14c age of cultured achatina fulica and the spatial features of 14c ages among modern land snail shells in china abstract it has long been known that many terrestrial snail shells are subject to the so called limestone effect however the magnitude and impact of this effect on the 13c values of snail shells and soft body tissue 13cshell and 13cbody are still unknown in this study achatina fulica snails were hatched and cultured under controlled conditions and supplied with 14c free calcium carbonate and lettuce a c3 plant as a calcium source and food supply respectively the snail shells and soft body tissues were sampled monthly for 5 months and 13c and radiocarbon dating analyses were conducted to trace carbon source variations at different growth stages our results show that the apparent 14c age of the shells and the corresponding 13cshell values increased progressively from the 1st to 3rd months and subsequently decreased during the 4th and 5th months the results demonstrate for the first time that carbonate ingestion has a straightforward influence on the 14c ages and 13c values of shells and that the limestone effect changes over the lifetime of snails moreover the apparent 14c ages of snails sampled in the field are older than modern ages when taken from the northern carbonate region and relatively young or the same as modern ages when collected from ferralic soils this further supports our findings from cultured snails and suggests that snail shells are good archives for radiocarbon dating purposes in southern china although the 13c values of the soft body tissues of cultured snails vary synchronously with those of the shell this seemingly common phenomenon cannot be easily explained by carbonate ingestion as the snail bodies are of more recent origin than the shells atmospheric co2 may be another candidate explaining the synchronicity between 13cshell and 13cbody as well as the f 14c variations of snail bodies however it is still unclear how snails differentially incorporate carbon from different sources e g carbonate and atmospheric co2 at different growth stages since carbon from different sources is combined in the bicarbonate pool in the hemolymph before being used by snails

holocene cultural and climate shifts in nw africa as inferred from stable isotopes of archeological land snail shells cultural transitions or even societal collapses have often been associated with long term drought events linkages between humans and the environment are best documented in well constrained archeol

shifts in oxygen and carbon isotope signals in marine molluscs from the central paratethys europe around the lower middle miocene transition abstract stable isotope data of mollusc shells from two adjacent time slices karpatian badenian from the central paratethys were investigated to detect differences in environmental parameters and to depict shifts in the isotope signature of the paratethyan seawater around the early middle miocene transition altogether seventeen different gastropod species and one bivalve species from the karpatian korneuburg basin and the badenian northern alpine foreland basin were selected representatives of various ecological guilds yielded different isotope patterns especially in 13c reflecting different original habitats or nutrition although molluscs precipitate their shells in oxygen isotopic equilibrium we preferred to compare isotope data of shells of the same genus of the family turritellidae from the karpatian and badenian the badenian turritella shells from the northern alpine foreland basin yielded distinctly higher 18o and 13c values than the respective karpatian shells from the korneuburg basin as the main factors controlling 18o values in gastropod shells are temperature and 18o of the water during precipitation the differences between the oxygen isotope data of the two time slices can only be explained by these factors good independent palaeotemperature proxies exist for the early to middle miocene of central europe they do not indicate a significant temperature variation therefore different 18o values of the seawater in the different basins of the central paratethys must be responsible for the contrasting 18o values when calculated with commonly assumed 18o seawater values for the miocene badenian turritella shells indicate too cold temperatures these data clearly document the danger of palaeotemperature interpretations based solely on stable isotopes as smaller and marginal marine settings such as the paratethys sea can be seriously influenced by regional differences in the isotope composition of the seawater only a thorough consistent control by other climate proxies e g palaeoecology of molluscs as in this study allows a sensible interpretation

land air boundary environment as recorded by the18o 16o and13c 12c isotope ratios in the shells of land snails abstract a yearly cycle of carbon and oxygen isotope composition of shells of the israeli land snailxeropicta vestalis is presented the18o 16o values indicate that the snails use water from the land air boundary zone the18o 16o ratio of the shells is in isotopic equilibrium with the water condensate from the vapour during the winter months during the summer months a contribution to the above water from soil water migrating upwards due to evaporation is noticeable the 13c values indicate that as in marine molluscs the carbon isotopic composition in land snails is controlled mainly by the aqueous carbonate compound which is in equilibrium with the land air boundary co2

stable isotope ecology of land snails from a high latitude site near fairbanks interior alaska usa abstract land snails have been investigated isotopically in tropical islands and mid latitude continental settings while high latitude locales where snails grow only during the summer have been overlooked this study presents the first isotopic baseline of live snails from fairbanks alaska 64 51 n a proxy calibration necessary prior to paleoenvironmental inferences using fossils 13c values of the shell 10 4 0 4 and the body 25 5 1 0 indicate that snails consumed fresh and decayed c3 plants and fungi a flux balance mixing model suggests that specimens differed in metabolic rates which may complicate paleovegetation inferences shell 18o values 10 8 0 4 were 4 higher than local summer rain 18o if calcification occurred during summer a flux balance mixing model suggests that snails grew at temperatures of 13 c rainwater 18o values of 15 and relative humidity of 93 results from fairbanks were compared to shells from san salvador bahamas at 24 51 n average annual 18o values of shells and rainwater samples from the bahamas were both 10 18o enriched with respect to seasonal summer alaskan samples at a coarse latitudinal scale shell 18o values overwhelmingly record the signature of the rainfall during snail active periods while tropical snails record annual average environmental information high latitude specimens only trace summer season climatic data

pleistocene holocene environmental change in the canary archipelago as inferred from the stable isotope composition of land snail shells abstract the isotopic composition of land snail shells was analyzed to investigate environmental changes in the eastern canary islands 28 29 n over the last 50 ka shell 13c values range from 8 9 to 3 8 at various times during the glacial interval 15 to 50 ka moving average shell 13c values were 3 higher than today suggesting a larger proportion of c4 plants at those periods shell 18o values range from 1 9 to 4 5 with moving average 18o values exhibiting a noisy but long term increase from 0 1 at 50 ka to 1 6 1 8 during the lgm 15 22 ka subsequently the moving average 18o values range from 0 0 at 12 ka to 0 9 at present calculations using a published snail flux balance model for 18o constrained by regional temperatures and ocean 18o values suggest that relative humidity at the times of snail activity fluctuated but exhibited a long term decline over the last 50 ka eventually resulting in the current semiarid conditions of the eastern canary islands consistent with the aridification process in the nearby sahara thus low latitude oceanic island land snail shells may be isotopic archives of glacial to interglacial and tropical subtropical environmental change

thermal dependency of shell growth microstructure and stable isotopes in laboratory reared scapharca broughtonii mollusca bivalvia we experimentally examined the growth microstructure and chemistry of shells of the bloody clam scapharca broughtonii mollusca bivalvia reared at five temperatures 13 17 21 25 and 29 c with a constant pco2 condition 450 atm in this species the exterior side of the shell is characterized by a composite prismatic structure on the interior side it has a crossed lamellar structure on the interior surface we previously found a negative correlation between temperature and the relative thickness of the composite prismatic structure in field collected specimens in the reared specimens the relationship curve between temperature and the growth increment of the composite prismatic structure was humped shaped with a maximum at 17 c which was compatible with the results obtained in the field collected specimens in contrast the thickness of the crossed lamellar structure was constant over the temperature range tested these results suggest that the composite prismatic structure principally accounts for the thermal dependency of shell growth and this inference was supported by the finding that shell growth rates were significantly correlated with the thickness of the composite prismatic structure we also found a negative relationship between the rearing temperature and 18o of the shell margin in close quantitative agreement with previous reports the findings presented here will contribute to the improved age determination of fossil and recent clams based on seasonal microstructural records

early middle holocene land snail shell stable isotope record from grotta di latronico 3 southern italy this paper compares stable isotope d 18 o and d 13 c records of early middle holocene land snail shells from the archaeological deposits of grotta di latronico 3 ltr3 southern italy with modern shell isotopic data no substantial interspecific variability was observed in shell d 18 o d 18 os of modern specimens pomatias elegans cornu aspersum eobania vermiculata helix ligata and marmorana fuscolabiata in contrast interspecific shell d 13 c d 13 cs variability was significant probably due to different feeding behaviour among species the d 18 os values of living land snails suggest that species hibernate for a long period during colder months so that the signal of 18 o depleted winter rainfall in their d 18 os is lost this suggests that d 18 os and d 13 cs values of pomatias elegans from this archaeological succession provide valuable clues for seasonal spring autumn climatic con ditions during the early middle holocene the d 18 os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records suggesting a substantial increase of precipitation and or persistent changes in air mass source trajectories over this region between ca 8 8 cal ka bp and 6 2 6 7 ka ago the d 13 cs trend suggests a transition from a slightly 13 c enriched to a 13 c depleted diet between early and middle holocene compared to present conditions we postulate that this d 13 cs trend might reflect changes in the c3 vegetation community potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric co2 concentration copyright 2010 john wiley sons ltd

oxygen and carbon stable isotopes of modern land snail shells as environmental indicators from a low latitude oceanic island abstract land snails provide a unique opportunity to study terrestrial paleoenvironments because their shells which are generally highly abundant and well preserved in the fossil record contain a temporal record of environmental change in the form of isotope codes to evaluate the utility of this approach for a low latitude oceanic setting 207 modern shells of 18 species of land snail were analyzed for their oxygen and carbon isotope composition along a north and south facing altitudinal gradient 10 2160 m a s l in tenerife island 28 n of the canary archipelago shells collected at each locality showed a relatively large range in isotope composition which was greater along the south facing transect drier and hotter suggesting that the variance in shell isotope values may be related to water stress although pooled isotope values did not generally show strong relationships with environmental variables i e altitude temperature and precipitation mean isotope values were strongly associated with some climatic factors when grouped by site the mean 18o value of the shell 18oshell by site displayed a negative correlation with elevation which is consistent with the positive relationship observed between temperature and the 18o value of rain 18orain calculated 18o values of the snail body water 18obody derived from observed temperatures and 18oshell values using the equation of grossman and ku grossman e l and ku t l 1986 oxygen and carbon isotope fractionation in biogenic aragonite chem geol isotope geosci sec 59 59 74 displayed a trend with respect to altitude that was similar to measured and hypothetical 18o values for local rain water the calculated 18obody values from the shell declined 0 17 vsmow per 100 m which is consistent with the altitude effect observed for tropical rains in western africa and it correlated negatively with rainfall amount accordingly lower 18oshell values indicate lower temperatures lower 18orain values and possibly higher rainfall totals a positive correlation between the mean 13c values of shells 13cshell and plants by site suggests that shells potentially record information about the surrounding vegetation the 13cshell values varied between 15 7 and 0 6 vpdb indicating that snails consumed c3 and c4 cam plants where more negative 13cshell values probably reflects the preferential consumption of c3 plants which are favored under wetter conditions individuals with more positive 13cshell values consumed a larger percentage of c4 plants other potential factors such as carbonate ingestion or atmospheric co2 contribution were unlikely that were more common at lower elevations of the hotter and drier south facing transect the relatively wide range of shell isotope values within a single site requires the analysis of numerous shells for meaningful paleoclimatic studies although small differences were observed in isotope composition among snail species collected at a single sampling site they were not significant suggesting that isotope signatures extracted from multi taxa snail data sets may be used to infer environmental conditions over a broad range of habitats

carbon and oxygen isotope composition of shell carbonate of desert land snails abstract variation in 13 c 12 c and 18 o 16 o ratios in the shell carbonate of several species of land snails was studied along a climatic gradient in semi arid to arid areas in the southern levant 13 c was found to be enriched in snails from communities having plants with a c 4 photosynthetic pathway depleted 13 c values were found in areas with high mean annual rainfall apparently due to higher input of metabolic co 2 as a result of greater snail activity shell carbonate 18 o values show a weak relation to the 18 o values of rainwater the shell 18 o values are enriched by 2 8 relative to isotopic equilibrium with environmental waters enrichment is suggested to result from metabolic effects on body water with lower activity producing greater enrichment but evaporation could also be a factor consistent differences in both 13 c and 18 o were found among species and may relate to the time when shell deposition occurs as with most paleoenvironmental indicators the application of shell isotopes is complicated by the multiplicity of controls of isotopic composition

stable isotope ecology δ18o δ13c δ15n of modern land snails along an altitudinal gradient in southern appalachian mountains usa abstract the first isotopic baseline is established for the snail neohelix from the big santeetlah creek watershed appalachian mountains shell 18o 3 6 to 0 4 declined with altitude 0 06 per 100 m and correlated with measured rain 18o a flux balance model suggests that relative humidity increased from 0 89 at 710 m to 0 91 at 1620 m in agreement with higher precipitation at higher altitudes coherent relationships between shell precipitation and humidity suggest that this taxon should be a valid paleoprecipitation archive in north america the respective 13c and 15n values of body 28 3 to 23 2 0 4 to 4 9 and shell organics 28 2 to 24 0 0 0 to 3 4 did not exhibit a trend with altitude and were uncorrelated with potential food resources a stable isotope mixing model suggests that neohelix primarily consume fungi 48 and lichen 17 with minimal ingestion of c3 plants the relative contributions of different food items however varied in an unpredictable fashion along the altitudinal gradient this study illustrates that even though snail foraging ecology from woodlands is complex and more variable than anticipated combining several isotope systems permits dietary inferences more easily than field observations alone

oxygen and carbon isotopic composition of modern terrestrial gastropod shells from lipari island aeolian archipelago sicily abstract oxygen 18os and stable carbon 13cs isotopic compositions of modern terrestrial gastropod shells from lipari island in the aeolian archipelago sicily have been analysed and compared with local meteoric water 18o 18op and vegetation 13c 13cv respectively results reveal that the 18os 18op relationship over the study area differs from those obtained on continental europe and italian shells implying that even at the scale of the mediterranean basin different relationships may co exist these differences have been interpreted as the increasing influence of mediterranean vapour water on tyrrhenian coasts at relatively low altitude up to 600 m asl which compensates for the effect of the 18op and possibly of temperature on shell 18o the steady state flux balance model fbm in agreement with previous studies suggests that snails are active prevalently at night shell carbon isotope ratios reflect the 13cv as predicted by the metabolic model and represent a valuable tool for identifying c3 plants with very distinct isotopic signatures

a late pleistocene refugium in mediterranean north africa palaeoenvironmental reconstruction from stable isotope analyses of land snail shells haua fteah libya abstract the late pleistocene to holocene archaeological record of north africa is key to understanding the emergence of anatomically modern humans into west asia and europe and the broadening of subsistence strategies in the shift from hunter gatherer to pastoral agricultural lifeways some contend that these developments were modulated by major shifts in climate and environment evaluation of this hypothesis requires the pairing of local and regional climate records with well dated archaeological sequences the haua fteah archaeological site in the gebel akhdar region of libya provides a key site to test this hypothesis as the cave contains one of the longest and most complete sequences of human occupation in north africa as well as abundant material for palaeoenvironmental reconstruction this study uses stable isotope analyses 18o and 13c of the terrestrial mollusc helix melanostoma to construct a palaeoenvironmental framework for interpreting north african human environment interactions from the upper palaeolithic to the neolithic 30 000 to 5000 years ago the land snail stable isotope records from haua fteah suggests that cool arid conditions in the cave peaked during marine isotope stage mis 2 this stage was however only marginally drier than previous and subsequent stages and coincided with an increase in occupation density in the cave this suggests that the gebel akhdar may have served as an environmental refugium from the more extreme aridity in the surrounding sahara and arid coastal plains for late stone age lsa populations in north africa conditions became progressively wetter towards the holocene however generally wetter conditions were interrupted by two arid episodes at c 8 0 ka and 7 3 ka that appear to coincide with regional changes reflected elsewhere in the mediterranean basin

implications for late holocene climate from stable carbon and oxygen isotopic variability in soil and land snail shells from archaeological site 41km69 in texas usa abstract well preserved fossil land snail shell collected in a 115 cm soil profile from archaeological site 41km69 in texas usa minimally span the past 2200 years and provide an opportunity to explore the paleoclimate implications of isotopic variability in shell carbonates bulk soil carbonates and soil organic matter carbon isotopic compositions 13 c values of modern and archaeological adult snail shell carbonates suggest significant 60 dietary input of c 3 plants during all periods oxygen isotopic compositions of shells suggest that the isotopic composition of environmental water available at the time of shell growth has changed little over the period of the profile a linearly decreasing trend in 13 c of soil organic matter from 22 8 at the bottom of the profile 115 cm below surface to 25 6 for modern surface samples indicate an overall 20 increase in abundance of c 3 plants this implies a progressively wetter climate and less severe water stress conditions or decreasing summer rainfall that is in agreement with other studies on late holocene climate change in the southern great plains usa these results strongly suggest a stable climate that favored c 3 vegetation in this portion of texas during this period

holocene 4 5 1 7 cal kyr bp paleoenvironmental conditions in central argentina inferred from entire shell and intra shell stable isotope composition of terrestrial gastropods the isotopic fingerprint of terrestrial gastropods has been increasingly used as a credible natural paleoenvironmental archive most published work has used this proxy at tropical and temperate latitudes of the northern hemisphere and focused on entire shell analysis the present study provides entire shell and intra shell isotopic profiles to infer average and seasonal late holocene environmental conditions in central argentina 30 s shells of plagiodontes daedaleus gastropoda odontostomidae were retrieved from the alero deodoro roca sector b site one of the few archaeological sites in central argentina rich in shells collected by pre hispanic hunter gatherer groups ancient entire shells exhibited values that were 2 5 higher in 13c and 1 8 higher in 18o than modern individuals pointing to higher abundance of c4 plants and overall drier conditions lower relative humidity and or higher rain 18o during 4 5 1 7 cal kyr bp than today in agreement with published regional proxies intra shel

terrestrial mollusk records from chinese loess sequences and changes in the east asian monsoonal environment abstract the terrestrial mollusk fossils found in chinese loess strata have been studied for over one hundred years however the greatest progress in these studies has been made only in the last two decades in this paper we review the advancements advantages and limitations of terrestrial mollusk studies in chinese loess deposits improvements in research methods and approaches have allowed the extraction of more detailed paleoenvironmental and paleoclimatic information from mollusk assemblages the broadened research scope and content have yielded many new findings and results the mollusk record has thus become one of the most important proxies in the paleoenvironmental and paleoclimatic reconstruction of loess paleosol sequences in china the greatest progress in the studies of terrestrial mollusks in chinese loess sequences can be summarized as follows 1 modern mollusk assemblages can be classified into four ecotypes based on their temperature and humidity requirements including eurytopic semi aridiphilous and sub humidiphilous cold aridiphilous and thermo humidiphilous types 2 quaternary mollusk assemblages can be modified into the following three ecological types glacial loess interglacial paleosol and interstadial weakly developed paleosol assemblages 3 mollusk records successfully reveal long term climatic and environmental changes reflective of the history of east asian monsoonal variations since the late cenozoic and the succession of mollusk species also indicate short term environmental changes such as millennial climate variability during last glacial maximum and unstable climatic fluctuations during glacial and interglacial periods and 4 more recently new analytical approaches have offered increased research potential in areas such as paleotemperature reconstruction using the isotopic compositions of modern and fossil mollusk shells combined with higher accuracy 14 c dating of quaternary loess deposits which will greatly improve future loess paleoenvironmental research

environmental significance of 13c 12c and 18o 16o ratios of modern land snail shells from the southern great plains of north america c 12 c and 18 o 16 o ratios of aragonite shells of modern land snails from the southern great plains of north america were measured for samples from twelve localities in a narrow east west corridor that extended from the flint hills in north central oklahoma to the foothills of the sangre de cristo mountains in northern new mexico usa across the study area shell y 18 o values pdb scale ranged from 4 1x to 1 2x while y 13 c values ranged from 13 2x to 0 0x y 18 o values of the shell aragonite were predicted with a published steady state evaporative flux balance model the predicted values differed with one exception by less than 1x from locality averages of measured y 18 o values this similarity suggests that relative humidity at the time of snail activity is an important control on the y 18 o values of the aragonite and emphasizes the seasonal nature of the climatic information preserved in the shells correlated y 13 c values of coexisting vallonia and gastrocopta suggest similar feeding habits and imply that these genera can provide information on variations in southern great plains plant ecology although there is considerable scatter multispecies transect average y 13 c values of the modern aragonite shells are related to variations in the type of photosynthesis i e c3 c 4 in the local plant communities the results of this study emphasize the desirability of obtaining isotope ratios representing averages of many shells in a locale to reduce possible biases associated with local variations among individuals species etc and thus better represent the bneighborhoodq scale temporal and or spatial environmental variations of interest in studies of modern and ancient systems d 2004 university of washington all rights reserved

stable isotope composition of middle to late holocene land snail shells from the marroquies archeological site jaen southern spain paleoenvironmental implications abstract the marroquies archeological site located in the metropolitan area of jaen 37 46 southern spain contains land snail shells which have been preserved jointly with other human and zooarcheological remains new radiocarbon analyses carried out on pristine domestic animal and human bones confirmed that these remains belong to the copper age interval 4470 3880 cal bp n 8 land snail entire shells of two species one herbivorous and one omnivorous were analyzed for 13 c 12 c and 18 o 16 o ratios to estimate the paleoenvironmental conditions prevailing during the middle to late holocene in the southernmost part of europe the 13 c values of fossil shells ranged from 13 8 to 8 1 n 15 whereas modern specimens ranged from 10 8 to 8 6 n 20 the fact that ancient and modern shells generally exhibited similar 13 c values suggests that the 13 c values of the vegetation have remained relatively stable during 4470 3880 cal bp and the present snail species did not differ in 13 c values despite their differing dietary habits the 18 o values of fossil shells ranged from 4 9 to 1 2 n 15 whereas modern specimens ranged from 2 8 to 0 9 n 20 fossil shells were on average 2 lower in 18 o values than modern shells calculations from a snail evaporative steady state flux balance model suggest that shells at 4470 3880 cal bp precipitated under appreciably higher relative humidity conditions than today whereas rain 18 o values and air temperatures at the soil air interface during snail active period were possibly similar although samples from this study represent a time period in which the well documented late holocene aridification trend in southern spain already started snails suggest conditions at 4470 3880 cal bp were yet noticeably wetter than at present this study shows that land snail shells preserved in holocene archeological sites offer valuable paleoenvironmental information in their isotope codes

stable carbon and oxygen isotopic composition of modern land snails along a precipitation gradient in the mid latitude east asian monsoon region of china abstract the stable oxygen and carbon isotope composition 18oshell and 13cshell of land snail shells preserved in chinese eolian loess deposits have the potential to reconstruct past changes in the east asian summer monsoon easm since the late oligocene to assess the potential of 18oshell and 13cshell for the semi quantitative reconstruction of past variations of the easm we studied modern snails and the corresponding vegetation composition of three distinct ecosystems woodland grassland and mountains spanning a large rainfall gradient 178 1403 mm in the mid latitude east asian monsoon region the results show that different snail species in the three ecosystems have significantly different values of 18oshell and 13cshell the snails in woodland from the eastern plain area have significantly lower 18oshell and 13cshell values than those of snails in grassland from the chinese loess plateau and the snails from the qinba mountains region have values intermediate between the two systematic variations of the 13c of snail shells body tissues and local plants are evident along the rainfall gradient indicating that 13cshell is mainly influenced by the 13c of ingested plants which is controlled by the easm we confirm that 13cshell is a reliable precipitation proxy and we obtained a new empirical equation 13cshell 0 0030 0 0003 map 8 80 0 32 r 0 76 n 74 p

younger dryas early holocene transition in the south eastern iberian peninsula insights from land snail shell middens the land snail sphincterochila candidissima from archeological records in villena se spain was studied isotopically to estimate the younger dryas yd early holocene transition in the western mediterranean live collected individuals exhibited body 21 8 1 6 and shell 5 8 1 4 d 13 c values typical of a c3 plant diet probably combined with carbonate ingestion calculations of a carbon flux balance mixing model suggest that living specimens experienced similar metabolic rates with comparable ratio of input and output fluxes of bicarbonate from the snail hemolymph all fossil shells showed comparable d 13 c values among each other but values were 2 higher than living specimens this may be explained by higher water stress at the yd holocene transition or by the suess effect shell d 18 o values averaged 1 3 0 8 for living individuals 0 5 0 8 for holocene 8 4 10 2 cal ka bp specimens and 0 4 0 6 for yd 12 0 12 4 cal ka bp snails an oxygen flux balance mixing model suggests that yd shells precipitated during relative humidity rh values of 79 82 after which rh increased gradually reaching maximum values of 87 88 at 8 4 8 6 cal ka bp and from there rh eventually declined to present values of 82 comparisons with other snail data suggest that the xerophilous sphincterochila records different environmental signatures fro other contemporaneous taxa copyright 2013 john wiley sons ltd

deciphering late quaternary land snail shell δ18o and δ13c from franchthi cave argolid greece this paper investigates the stable isotopic composition from late pleistocene holocene 13 to 10 5 cal ka bp shells of the land snail helix figulina from franchthi cave greece it explores the palaeoclimatic and palaeoenvironmental implications of the isotope palaeoecology of archaeological shells at the time of human occupation of the cave modern shells from around the cave were also analysed and their isotopic signatures compared with those of the archaeological shells the carbon isotope composition of modern shells depicts the consumption of c3 vegetation shell oxygen isotopic values are consistent with other mediterranean snail shells from coastal areas combining empirical linear regression and an evaporative model the 18os suggest that modern snails in the study area are active during periods of higher relative humidity and lower rainfall 18o probably at night late glacial and early holocene 18os show lower values compared to modern ones early holocene 18os values likely track enhanced moisture and isotopic changes in the precipitation source by contrast lower late glacial 18o could reflect lower temperatures and 18op compared to the present day shell carbon isotope values indicate the presence of c3 vegetation as main source of carbon to late glacial and early holocene snails