paleoclimatic interpretations of buried paleosols within the pre illinoian till sequence in northern missouri usa abstract northern missouri preserves shallow buried paleosols ranging in age from early to late pleistocene that are developed in six pre illinoian tills beneath illinoian mis 6 and wisconsinan mis 4 2 loess the morphology of these paleosols changes with age reflecting a changing climate during the pleistocene and cosmogenic nuclide burial dates of the respective sola provide age control on the timing of these changes the depth to secondary calcium carbonate nodules within the weathering profiles increases with younger age indicating a transition to moister conditions during the pleistocene and these nodules are absent entirely within the modern soils after approximately 0 4 ma the sola became distinctly redder even as the time available for pedogenesis became shorter culminating in the bright red sangamon geosol mis 5 this trend is consistent with increasing interglacial temperatures and or precipitation finally erosion rates determined from cosmogenic nuclide concentrations within the sola also increase systematically with younger age this increase may be due to some combination of changing climate more frequent glaciations and the deposition of a thick cover of unconsolidated glacial sediment above the stable residuum dominated preglacial landscape

pedogenic carbonates and carbon pools in gypsiferous soils of a semiarid mediterranean environment in south italy abstract soil carbonates are key features in soils of arid and semiarid environment playing an important role from pedogenetic landscape history paleoclimatic and environmental points of view the objectives of this work were i to study pathways of pedogenic carbonate pc formation ii to distinguish between lithogenic and pedogenic inorganic c by using the natural c isotope abundance and iii to estimate the soil c pools in a gypsiferous semiarid mediterranean environment sicily italy five soil pedons developed on calcareous and non calcareous parent materials from holocene 10 000 years bp to upper tortonian 7 2 5 3 ma bp in age were surveyed during field soil description the highest stage of carbonate morphology was found in soils developed on non calcareous holocene colluvial deposits youngest deposits in age which also showed the highest amount of pc the great amount of pc in soils developed on youngest deposits was ascribed to a soil landscape relationships being located in a doline overhung by gypsum outcrops precipitation of ca 2 from gypsum dissolved by rainfall and biogenic co 2 is reliable the significant positive relationship between soil organic c and pedogenic carbonates 13 c values confirms that pc was formed from biogenic co 2 organic c pool in the first cubic meter of soil ranged from 17 to 42 kg whilst pedogenic inorganic c pool from 2 8 to 30 7 kg the estimated rate of inorganic c accumulation in soils developed on youngest deposits was 2 5 g m 3 y 1 whereas the rate was negligible on older parent material the hypothesized pathways of pc formation were ex novo precipitation of gypsum ca 2 and biogenic co 2 and dissolution of lithogenic caco 3 and re precipitation of ca 2 with biogenic co 2 from an environmental prospective investigated soils may act as a sink of c when ca 2 from gypsum is available for the formation of pedogenic carbonates

ocean circulation and calcareous nannoplankton evolution during the jurassic and cretaceous abstract spatial and temporal distribution of calcareous nannoplankton aid in the reconstruction of ocean circulation during the cretaceous biogeographic patterns of calcareous nannoplankton during the late cretaceous are mostly zonal reflecting mostly latitudinal gradients of surface water temperature during the middle cretaceous calcareous nannofossil assemblages are more strongly affected by surface water fertility concentration of limiting nutrients especially in a wide tropical belt between 50 and 45 n latitudes major upwelling regions off northwest africa in the south atlantic and the equatorial pacific divergence are apparent temporal changes in the composition of middle cretaceous nannofloras are indicative of changes in surface water fertility and vertical mixing at frequencies of tens to hundreds of kiloyears ka changes in the intensity of atmospheric circulation with frequencies close to the milankovitch cycles appear to be the ultimate cause of these minor changes in the circulation of the upper ocean calcareous nannofossil preservation patterns show that during the middle cretaceous deep waters were quite homogeneous with respect to carbonate saturation in the atlantic ocean but not in the indo pacific ocean where a more distinctive calcite compensation depth ccd is apparent water mass structure of the major oceans during the mesozoic was thus quite different taxonomic evolution of calcareous nannofossils was also strongly affected by ocean circulation and fertility major peaks in the rates of diversification coincide with anoxic events that is periods of increased preservation of organic carbon in the oceans which coincide with high sea level stands during anoxic events ocean circulation was sluggish vertical mixing was slow deep ocean ventilation poor and the concentration of limiting nutrients in surface waters was low increased competition for limiting nutrients and possibly preferential cropping of the dominant forms by zooplankton resulted in increased rates oof speciation during anoxic events periods of major production of nannofossil carbonate coincided with low sea level stands when oceans were more vigorously stirred and surface waters were more fertile the first such period was the latest jurassic when calcareous nannoplankton invaded the open oceans and became the major carbonate producers in the pelagic realm during the mesozoic the frequency of peaks and troughs in evolutionary rates is on the order of 10 30 ma and appears to be irregular the coincidence of periods of anoxia with high sea level stands which in turn appear to be caused by more rapid sea floor spreading indicates that the ultimate diving forces of nannoplankton evolution are processes in the earth s mantle these major tectonically driven fluctuations in ocean atmosphere circulation with frequencies of a few million to a few tens of millions of years are hereby named fischer cycles superimposed astronomically driven milankovitch cycles affected relative abundance patterns but not taxonomic evolution of calcareous nannoplankton rates of nannoplankton extinction are about five times higher than background rates at the end of the jurassic and orders of magnitude higher in the latest cretaceous possibly indicating a terrestrial or extraterrestrial catastrophe

early jurassic carbon and oxygen isotope records and seawater temperature variations insights from marine carbonate and belemnite rostra pieniny klippen belt carpathians abstract new carbon and oxygen isotope records and discussion of the main variations in seawater temperature through the sinemurian aalenian of the pieniny klippen basin northern tethys ocean are presented herein comparison of the recorded changes in stable isotope compositions of bulk carbonate and belemnite rostra from an open marine environment with previously documented predominantly restricted epicontinental data enables determination of major climatic events that were most likely of worldwide extent a slight positive 13c shift is recorded in the lowermost upper pliensbachian a significant positive excursion in carbonate carbon isotope values is documented in the lower toarcian serpentinum zone furthermore the 13c values display a falling trend in the lower upper toarcian and relatively constant values in the aalenian temperatures inferred from the 18o values of well preserved belemnite rostra suggest rather cool seawater conditions 10 13 c in the pieniny klippen basin during the late sinemurian warming by 4 c in the early pliensbachian and then cooling by 8 c in the late pliensbachian the seawater temperature rose once more in the early toarcian and began to fall again during the middle toarcian in the middle late aalenian seawater temperatures oscillated between 10 and 13 c

pedogenic carbonates forms and formation processes abstract soils comprise the largest terrestrial carbon c pool containing both organic and inorganic c soil inorganic carbon sic was frequently disregarded because 1 it is partly heritage from soil parent material 2 it undergoes slow formation processes and 3 has very slow exchange with atmospheric co2 the global importance of sic however is reflected by the fact that sic links the long term geological c cycle with the fast biotic c cycle and this linkage is ongoing in soils furthermore the importance of sic is at least as high as that of soil organic carbon soc especially in semiarid and arid climates where sic comprises the largest c pool considering the origin formation processes and morphology carbonates in soils are categorized into three groups geogenic carbonates gc biogenic carbonates bc and pedogenic carbonates pc in this review we summarize the available data and theories on forms and formation processes of pc and relate them to environmental factors after describing the general formation principles of pc we present the specific forms and formation processes for pc features and the possibilities to use them to reconstruct soil forming factors and processes the following pc are described in detail earthworm biospheroliths rhizoliths and calcified roots hypocoatings nodules clast coatings calcretes and laminar caps the second part of the review focuses on the isotopic composition of pc 13c 14c and 18o as well as clumped 13c and 18o isotopes known as 47 the isotopic signature of pc enables reconstructing the formation environment the dominating vegetation 13c temperature 18o and 47 and the age of pc formation 14c the uncertainties in reconstructional and dating studies due to pc recrystallization after formation are discussed and simple approaches to consider recrystallization are summarized finally we suggest the most important future research directions on pc including the anthropogenic effects of fertilization and soil management in conclusion pc are an important part of sic that reflect the time periods and formation processes in soils a mechanistic understanding of pc formation is a prerequisite to predict terrestrial c stocks and changes in the global c cycle and to link the long term geological with short term biological c cycles

miocene burdigalian seawater and air temperatures estimated from the geochemistry of fossil remains from the aquitaine basin france abstract construction work of the highway a65 led the top of the burdigalian molasses de l armagnac formation to outcrop in two close localities near the town of bazas and marimbault situated on the western edge of the aquitaine basin france from this formation a rich fossil assemblage has been recovered and includes both marine and terrestrial fossil remains which offered the opportunity to reconstruct both seawater and terrestrial air temperatures at a regional scale during the burdigalian for this purpose two sets of fossil samples representative of the whole assemblage have been selected for each locality they include teeth and bones of sharks fish rays reptiles and mammals as well as tests of sea urchins and shells of bivalves first we performed rare earth element ree analyses of 53 apatite samples from both localities in order to characterize the diagenetic history of the assemblage we then analysed the oxygen isotope composition of 49 biogenic apatite phosphate samples and 6 biogenic carbonate samples representing both marine and terrestrial organisms using published isotopic fractionation equations both seawater and terrestrial air temperatures were reconstructed calculated seawater temperatures using phosphate and carbonate isotopic thermometers are 23 4 c and 25 1 c respectively for the locality of mendouillet bazas and 24 4 c and 26 1 c respectively for the locality of monbalon miron marimbault calculated terrestrial air temperatures are 18 2 c for the locality of mendouillet and 17 2 c for the locality of monbalon miron these regional temperatures are in good agreement with seawater and terrestrial temperatures calculated for other european localities of contemporaneous periods these results also fit the global climatic context of the mid miocene climatic optimum starting at the end of the burdigalian even though the global climatic conditions were warmer than today during the end of the burdigalian calculated continental and seawater thermal gradient at mid latitude appear to have been comparable to present day ones

carbon and oxygen isotope fractionations between aragonite and calcite of shells from modern molluscs carbon and oxygen isotope fractionations between calcite and aragonite were investigated by analyzing marine gastropods and bivalves that lived under temperate to tropical climates species that secrete both aragonite and calcite layers were studied to ensure similitude of changes in the isotopic composition of water in diet and in metabolic activity during shell growth aragonite and calcite layers from the adult parts of the shell were identified and mapped by using raman spectroscopy powder samples were obtained by micro drilling under a stereo microscope thirty six pairs of aragonite calcite samples were obtained from ten gastropod and five bivalve species biogenic aragonite is c 13 enriched by 0 95 0 81 and o 18 enriched by 0 37 0 65 relative to co existing biogenic calcite direction and magnitude of the carbon isotope fractionation are compatible with those already determined by using low temperature experimental approaches the observed oxygen isotope difference between biogenic aragonite and calcite is assigned to the difference similar to 0 4 parts per thousand in the acid fractionation factor values that must be taken into account during digestion of carbonate polymorphs at 90 degrees c it is concluded that biogenic calcium carbonate polymorphs precipitate close to but not in isotopic equilibrium with seawater therefore empirical oxygen isotope fractionation equations that were established on the basis of modern mollusc shells and ambient waters should be preferred for the calculation of aquatic paleotemperatures

reconstruction of palaeosalinity using carbon isotopes and benthic associations a comparison carbon and oxygen isotopes were determined on 40 recrystallized shells of late jurassic bivalves from the lusitanian basin of portugal in contrast with the oxygen isotopes which exhibited considerable diagenetic distortion the carbon isotopes are thought to preserve a record of the salinity of the jurassic marginal marine seas in which these bivalves lived the reconstructed palaeosalinities range from 35 o euhaline to 5 oligohaline comparing these values with the palaeosalinity reconstructed from a palaeoecological analysis of 17 stratigraphic levels within the basin the independently derived values agree in most cases strongly differing values are explained as being due to biotic factors and to diagenetic distortion of the isotopic signal they are less likely to be due to smallscale time averaging or insufficient microstratigraphic sampling on the whole the carbon isotope analyses are thought to produce reasonable palaeosalinity values although data from infaunal originally aragonitic bivalves appear to be less reliable than those from epifaunal bivalves with a predominantly or exclusively calcitic shell as diagenetic alteration of the carbon isotope signal is however unpredictable and biotic effects on the isotopic composition are insufficiently known palaeosalinity reconstructions based on stable isotope data should be supported by palaeoecological data

the origin and timing of multiphase cementation in carbonates impact of regional scale geodynamic events on the middle jurassic limestones diagenesis paris basin france the middle jurassic carbonates of the eastern part of the paris basin display surprisingly low values of porosity and permeability 15 and k 0 5 md the main objective of this study is to determine the causes and timing of the cementation that altered the petrophysical properties of these carbonates thereby destroying their potential as oil reservoirs a fate that did not befall their equivalents in deeper central parts of the paris basin using petrographic and geochemical analyses stable o and c isotopes sr isotopes major elements we identify six calcitic spar stages two dolomite stages and several episodes of fracturing and stylolitization ordered in paragenetic sequence cement quantification shows the predominance of two blocky calcite cement stages 75 of total cementation o and sr isotopes from these calcite cements suggest that the parent fluids resulted either from a mixing of trapped jurassic seawater and meteoric water or from buffered meteoric waters in the geological history of the paris basin major meteoric water inputs were possible during the early cretaceous when the middle jurassic carbonates cropped out at its northern and eastern borders lateral meteoric recharge may have occurred as a result of two separate uplift events late cimmerian unconformity and late aptian unconformity and the related exposures of carbonates to the north of the study area this palaeohydrological circulation brought about a significant reduction of porosity from 40 to 10 through calcite cement precipitation the early cretaceous events are of great importance in the diagenetic evolution of the sedimentary basins bordering the london brabant massif across all of northwestern europe a subsequent dolomite and calcite cementation stage accounts for about 5 of the total cement volumes this late cementation may have been caused by hydrothermal fluids ascending along permeable fractures during the late oligocene extension episode

middle to late holocene environmental changes in the depositional system of the tropical brackish bolgoda lake coastal southwest sri lanka abstract the tropical bolgoda lake is one of the largest lagoonal estuaries in sri lanka organic constituents in this lake were investigated using 28 surface sediments three cores from the lake and four short cores from mangrove mud elemental and molecular compositions of sediments and living organic matter om were determined using cns elemental analysis and gas chromatography mass spectrometry respectively chronology of events was determined using accelerated mass spectrometry ams 14 c data for bulk oms woods and mollusk shells the history of bolgoda lake can be divided into two major chrono stratigraphic divisions namely a lower sedimentary succession from ca 7 0 cal ky b p to 2 5 cal ky b p and an upper sedimentary succession from ca 2 5 cal ky b p to the recent according to the sapropelic depositional system concentrations of the mangrove biomarker taraxone increased significantly at ca 7 0 cal ky b p the lower part of the sediment sequence had moderate productivity and was mainly deposited under marine terrestrial influence in oxygen poor anoxic conditions during mid holocene sea level highstands a drastic increase in total organic carbon toc content reaching 29 was found in one of the bolgoda cores this increase occurred because of sea level regression at about 2 5 cal ky b p this change was probably caused by development of a beach rock sandbar and the estuary system changed to a semi closed lake due to the sea level regression as a result aquatic vascular plants predominate in this depositional system after ca 2 5 cal ky b p toc content decreased slightly but relatively high toc contents were maintained in the muddy sediments in moderately sized and shallow 1 2 m tropical estuaries lagoons such as bolgoda lake drastic changes in toc contents may be the most sensitive indicator of sea level variations increase in higher plant om with higher n c 29 n c all and n c 37 n c all alkane ratios also suggest a climatic transition from wetter to somewhat drier after the middle holocene accumulations of pyrogenic polycyclic aromatic hydrocarbons pahs in the modern sediments record anthropogenic activity after european settlement in the 15th century

geohydrology of the laura fresh water lens majuro atoll a hydrogeochemical approach in small limestone islands the depositional history and subsequent chemical interactions between ground water and the aquifer host rock play critical roles in the occurrence movement and chemical quality of ground water the hydrogeochemistry of the laura fresh water lens majuro atoll marshall islands is an example of these relations laura is underlain by two principal hydrologic units the upper unit is a back reef marginal lagoonal deposit which formed during the holocene interglacial stage it is composed of moderately permeable carbonate sediments the lower hydrologic unit consists of highly permeable limestone that was subaerially exposed most likely during a pleistocene glacial lowstand similar stratification is found at bikini and enewetak atolls the upper hydrologic unit contains a calcium bicarbonate rich fresh water lens in which a potable fresh water nucleus as much as 14 m thick occurs on the lagoon side of the island storage in the fresh water nucleus ranged from 1 70 x 10 6 to 2 08 x 10 6 m 3 during 1984 1985 ground water occurrence and flow are governed by an asymmetric distribution of lithofacies about the longitudinal axis of the island and an abrupt increase in permeability at the contact between the upper and lower hydrologic units the highly permeable lower hydrologic unit contains sea water and truncates the fresh water sea water mixing zone the fresh water lens and associated fresh water sea water mixing zone are the site of continuously occurring diagenetic reactions that significantly affect the porosity and permeability of the aquifer non equilibrium dissolution precipitation reactions coupled with variations in co 2 input control the chemical evolution of laura ground water at the present rate of chemical weathering 465 m 3 of sediment are being dissolved and transported to the sea by ground water each year this dissolution results in an annual increase in porosity of 0 01 the primary factors controlling the occurrence and flow of ground water in the leeward reef islet of laura are 1 the depositional history of the upper hydrologic unit which has resulted in a greater accumulation of low permeability fine grained sediments beneath the lagoon side of the island and a high to low permeability coarse to fine grained sediment gradation between the ocean and lagoon and 2 the diagenetic history of the lower hydrologic unit which has resulted in a highly permeable basement

paleogene stable isotope events the oxygen isotope record in paleogene benthic foraminifera shows that at the base of the paleogene the ocean deep waters had a temperature of about 10 c rising to about 12 c at the base of the eocene and cooling between 51 ma and 49 ma to about 9 c the most dramatic event occurred just after the eocene oligocene boundary at about 35 8 ma when ocean deep waters cooled by several degrees within 104 105 yr probably in association with temporary glaciation in the antarctic region another more intense glacial event in antarctica may have occurred later in the oligocene at about 31 ma and a third near the top of the oligocene at 24 ma in the marine carbon isotope record a very rapid negative excursion occurred precisely at the cretaceous tertiary boundary a recovery to unusually positive values in the late paleocene was followed by a second negative excursion close to the paleocene eocene boundary that was even more extreme in magnitude although it was not as rapid these major carbon isotope events permit very accurate stratigraphic correlation there are many other smaller features in the carbon isotope record that will also prove useful for this purpose

oxygen isotope records of the australian flat oyster ostrea angasi as a potential temperature archive abstract the response of the oxygen isotope ratio 18o in shells of the australian native flat oyster ostrea angasi to changes in water temperature has been assessed using growth experiments conducted for one year at two locations on the east coast of australia the analysed 18o of the oyster shells 18oshell closely follows the predicted oyster shell 18o constructed from measured 18o in the water 18owater and water temperature influxes of freshwater that occur in the estuarine habitats of o angasi can modify the 18owater and consequently 18oshell salinity fluctuations can also cause interruptions to shell growth in this species this can cause overestimated temperatures in o angasi 18oshell temperature reconstructions a 18oshell temperature calibration was established for o angasi yielding the relationship t c 13 97 3 57 18oshell 18owater 0 17 18oshell 18owater 2 n 79 r2 0 79 which within the experimental uncertainties of the data is similar to other published biogenic carbonate paleotemperature equations

tertiary oxygen isotope synthesis sea level history and continental margin erosion tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale making use of improved chronostratigraphic control and additional oligocene isotope data synchronous changes in both benthic and planktonic 18o values which occurred in the oligocene to miocene 36 5 2 ma are interpreted in part to represent ice growth and decay the inferred ice growth events correlate with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records this association is consistent with a link between oligocene to miocene erosional events and rapid 15 m m y glacioeustatic lowerings of about 50 m high benthic foraminiferal 18o values suggest the presence of continental ice sheets during much of the oligocene to recent 36 0 ma substantially ice free conditions probably existed throughout the paleocene and eocene 66 36 ma the mechanisms and rates of sea level change apparently were different between the early and late tertiary with glacioeustatic changes restricted to the past 36 m y pre oligocene erosion on passive continental margins was caused by eustatic lowerings resulting from global spreading rate changes we apply a model which suggests that large areas of the continental shelves were subaerially exposed during such tectonoeustatic lowstands stimulating slope failure and submarine erosion the different mechanisms and rates of eustatic change may have caused contrasting erosional patterns between the early and late tertiary on passive continental margins this speculation needs to be confirmed by examination of data from several passive margins

modeling the genesis of luvisols as a function of topographic position in loess parent material this article has been withdrawn at the request of the authors and editors the publisher apologizes for any inconvenience this may cause the full elsevier policy on article withdrawal can be found at http www elsevier com locate withdrawalpolicy

chemical weathering in two adirondack watersheds past and present day rates rates of chemical weathering in two forested adirondack watersheds were determined from mineral and elemental depletion trends in soil profiles and from input output budgets based on precipitation and surface water chemistry long term rates of weathering have averaged about 500 to 600 eq ha yr for both watersheds since the glaciers retreated from the region about 14 000 yr ago present day denudation rates average 1679 eq ha yr in the panther lake watershed and only 198 eq ha yr in the woods lake watershed mineral weathering reactions in both watersheds involve primarily the dissolution of plagioclase potassium feldspar and hornblende mass balance calculations however indicate that hornblende weathers in disproportionately large amounts in the panther lake watershed relative to its abundance in soils and till cation exchange in the glacial till mantling the panther lake watershed may also play an important role in controlling surface water chemistry in the basin in the panther lake watershed the current rate of weathering which is about a factor of 3 greater than the long term average may reflect a recent adjustment for higher hydrogen ion fluxes brought about by acid deposition the capacity of the thick till deposits in the panther lake watershed to neutralize acidity is ultimately reflected by the circum neutrality of panther lake in the woods lake watershed the soils and thin till deposits cannot effectively neutralize current acid loadings and therefore woods lake is acidic with a ph below 5

middle upper jurassic stable isotope records and seawater temperature variations new palaeoclimate data from marine carbonate and belemnite rostra pieniny klippen belt carpathians abstract the carbon and oxygen isotope composition of well preserved belemnite rostra and bulk carbonates from uppermost aalenian to lower tithonian outcrops of the pieniny klippen belt in the carpathians is under discussion in this paper new isotope and elemental data from the open marine basin in a rarely studied northern part of the tethys ocean corroborate the world wide 13 c variations and global temperature changes of a seawater the 13 c temporal trends display prominent positive shift in the upper callovian middle oxfordian as well as a declining trend in the kimmeridgian tithonian interval 18 o values of belemnite rostra suggest a decrease in temperatures during the latest aalenian early bajocian the upper jurassic temperatures estimated on the basis of oxygen isotope values and mg ca ratios of belemnite rostra indicate a warming of the seawater of ca 5 5 c in the late oxfordian early kimmeridgian this temperature rise is interpreted to be a result of the global climate warming present during the early late jurassic

sclerochronology of busycon sinistrum late prehistoric seasonality determination at st joseph bay florida usa abstract recent archaeological investigations indicate that coastal fort walton cultures in the st joseph bay region of northwest florida emphasized marine and estuarine foraging these late prehistoric mississippi period a d 1000 1500 peoples collected fish shellfish and other aquatic resources at the richardson s hammock site 8gu10 radiocarbon dated to about a d 1300 large predatory gastropods were a major subsistence component this adaptation is in sharp contrast with that of contemporaneous inland fort walton societies who relied on maize agriculture and raises the question whether coastal groups were separate hunter gatherer fisher populations or migrated seasonally from inland farming villages we perform stable oxygen and carbon isotope sclerochronology on lightning whelks busycon sinistrum to determine the seasonality of fort walton foraging and to compare the environment of prehistoric st joseph bay with that of the modern bay oxygen isotope profiles suggest that shellfish collecting was relegated primarily to the summer months producing a scheduling conflict with the primary growing season for maize in northwest florida thus coastal and inland fort walton sites probably represent separate culture groups the relationship between 18oshell and 13cshell indicates similar environmental and climatic conditions between prehistoric st joseph bay and today however modern whelks are depleted in 13c compared to fort walton whelks which reflects both twentieth century co2 emissions and years of dredging and wastewater pollution entering the bay

high resolution paleosalinity reconstruction from laguna de la leche north coastal cuba using sr o and c isotopes abstract isotopes of sr o and c were studied from a 227 cm long sediment core in order to develop a high resolution paleosalinity record to investigate the paleohydrology of laguna de la leche north coastal cuba during the middle to late holocene palynological plant macrofossil foraminiferal ostracode gastropod and charophyte data from predominantly euryhaline taxa coupled with a radiocarbon based chronology indicate that the wetland evolved through four phases 1 an oligohaline 0 5 5 lake existed from 6200 to 4800 cal yr b p 2 water level in the lake increased and the system freshened from 4800 to 4200 cal yr b p 3 a mesohaline 5 18 lagoon replaced the lake 4200 cal yr b p and 4 mangroves enclosed the lagoon beginning 1700 cal yr b p forming a mesohaline lake isotopic ratios were measured on specimens of the euryhaline foraminifer ammonia beccarii although several measurements were also made on other calcareous microfossils in order to identify potential taphonomic and or vital effects the 87sr 86sr results show that the average salinity of laguna de la leche was 1 7 during the early lake phase and 8 during the lagoon phase a change driven by relative sea level rise the 18o results do not record the salinity increase seen in the 87sr 86sr data but instead indicate high evaporation from the lake surface this in turn suggests that the value of 1 7 may slightly underestimate the average salinity of the wetland at least for the period prior to 4800 cal yr b p variability in 13c was controlled by plant productivity episodic marine incursions and vegetation community change there is some evidence for seasonal effect and the lateral transport of microfossils prior to burial the isotopic data independently confirm the hydrological interpretations made using the euryhaline indicators and have permitted the reconstruction of a significantly higher resolution paleosalinity record than would be possible using the paleoecological data however our results show that sr isotopes while often cited as a powerful paleosalinity tool must be used in conjunction with other indicators when investigating paleosalinity trends relying solely on any single isotopic or ecological indicator can lead to inaccurate results especially in semi enclosed and closed hydrological systems

weathering processes in superficial deposits regolith and their influence on pedogenesis a case study in the swiss jura mountains abstract the last glacial period left a mantle of freshly reworked sediments covering the european landscape glacial periglacial fluvio glacial and aeolian dynamics enhanced transportation and mixing of materials generating new superficial deposits in which holocene soils developed these assorted surface sediments often differed from the underlying bedrock in their lithological composition and texture and were delimited by lithological discontinuities in the swiss jura mountains the mesozoic limestone bedrocks are covered by various superficial deposits moraines cover beds loess deposits cryoclasts etc which reduce or even suppress the influence of limestone on present day soil development in this context soils and their underlying bedrock no longer present a genetic continuity the nature and relationships between these deposits is studied within a toposequence of soils in terms of their mineralogical and geochemical compositions three main superficial deposits limestone bedrock clasts loess and non carbonate moraine are used as reference materials in order to characterize the complex mixing of sediments through the toposequence soils with limestone clasts undergo decarbonation and decalcification processes iron rich alpine loess deposits composed of fine silicate particles enhance brunification process in soils a non carbonate alpine moraine displays the most acidic conditions within the toposequence due to enhanced leaching clay and ions processes consequently the reworked surface sediments including limestone cryoclasts moraines and cover beds have a prevailing influence on pedogenesis compared to the hard underlying bedrock

the giant marine gastropod campanile giganteum lamarck 1804 as a high resolution archive of seasonality in the eocene greenhouse world

constitutive mass balance relations between chemical composition volume density porosity and strain in metasomatic hydrochemical systems results on weathering and pedogenesis relations characterizing the chemical physical and mechanical changes resulting from metasomatic hydrochemical processes are developed using mass balance models which formally link chemical composition to bulk density mineral density volumetric properties porosity and amount of deformation strain rigorous analysis of aqueous solute transport effects is then made possible in a variety of porous media flow environments including chemical weathering pedogenesis soil formation diagenesis ore deposition and enrichment and metamorphism application of these linear constitutive relations to chemical weathering profiles shows that immobile and locally mobile chemical elements with masses conserved on the scale of soil profiles can be accurately identified from analysis of appropriate data arrays and then used as natural geochemical tracers to infer the nature and extent of hydrochemical weathering processes and volume changes during pedogenesis assumptions commonly made in the past about the supposed immobility of certain elements e g ti and zr become unnecessary quantitative differentiation between the effects of residual and supergene fractionation is then easily made these methods are applied to ni rich laterites developed by weathering of ultramafic rocks showing that during ordinary residual enrichment ni is concentrated by as much as 4 protolith peridotite concentrations this occurs simply by silicate mineral dissolution and removal of chemical elements other than ni e g mg with a corresponding reduction in saprolite density and increase in bulk porosity without significant deformation in contrast laterites with mineable concentrations of ni which are similarly undeformed such as the nickel mountain mine in riddle oregon have experienced in addition to residual enrichment strong supergene enrichment by fractionation of ore elements between a leached zone from which ni is extracted and a complementary enriched zone positioned farther along the direction of ground water flow soil forming processes in podzol chronosequences developed on sandy beach terraces of the mendocino coast of california involved soil column collapse of 60 percent by dissolution of silicate minerals in the albic horizon of al and fe leaching and 70 percent dilation expansion in the overlying organic rich layer by root growth the amount of erosion based upon paleosurface reconstructions using the excess mass of fe al pb ga and cu in the zone of supergene enrichment spodic horizon below the ground water table indicates that subsurface erosion by dissolutional collapse is three times that of surficial erosion finally using published chemical data for ti zr and cr on major bauxite deposits in australia where erosion rates are thought to be low we infer that there may have been major amounts of dissolutional collapse to explain the upwards increase of detrital zircon and rutile in weathering profiles

and ratios in skeletal calcite of mytilus trossulus covariation with metabolic rate salinity and carbon isotopic composition of seawater minor element and isotopic compositions of marine bivalve calcite are frequently used as proxy records of seawater temperature and salinity although molluscan calcite is secreted at or near oxygen isotope equilibrium the influence of metabolic activity i e vital effects on skeletal srca ratios and 13c values is not well known we present measurements of skeletal chemistry from a consecutive samples milled in chronological order from the organism s final year of growth and b adjacent samples within three separate growth bands of the marine mussel mytilus trossulus to investigate chemical disequilibrium effects among different parts of the shell seawater temperature and salinity were monitored for one year at squirrel cove british columbia at the end of the year a young rapidly growing mussel mussel a and an old slowly growing mussel mussel b were harvested from this site growth bands within the shells were sampled to provide a chronological record of shell carbonate chemistry results from consecutive samples show 1 a significantly higher average srca ratio in mussel a than that in mussel b and 2 13c values that correlate well with salinity in mussel a but not in mussel b results from time equivalent adjacent samples show 1 higher srca and 13c values near the ventral margin than at time equivalent regions on lateral margins of the shell and 2 little or no variation in 18o values these observations suggest that skeletal chemistry srca and 13c is primarily controlled by rate of mantle metabolic activity and secondarily modified by variation in seawater salinity because metabolic activity in the mantle at the site of carbonate precipitation varies with shell curvature the composition of calcite secreted along lateral margins is influenced to a greater extent by metabolic activity than calcite secreted coevally at the central margin of the shell hence the chemistry of calcite secreted at the ventral margin is precipitated in near equilibrium with seawater and allows accurate estimation of seawater srca ratios and carbon isotopic composition in contrast shell precipitation along lateral margins is dominantly controlled by metabolic activity and calcite chemistry is not in equilibrium with ambient seawater in this context we present a biomineralization model where variations in skeletal srca and 13c values are explained in the context of mantle metabolic activity and seawater salinity

palaeoenvironmental reconstruction of the sarmatian middle miocene central paratethys based on palaeontological and geochemical analyses of foraminifera ostracods gastropods and rodents paleoenvironmental changes in the upper middle miocene central parathetys were reconstructed by using qualitative and quantitative palaeontological analyses of foraminifera and ostracods coupled with trace elemental mg ca and stable isotope delta 18 o and delta 13 c analyses of their carbonate skeletons and of gastropod sheets mean annual air temperatures were estimated using the oxygen isotope composition of contemporaneous rodent teeth the studied aquatic fossils come from two boreholes in the zsambek basin northern central hungary while the terrestrial ones are from localities in ne hungary and e romania in the studied sarmatian successions three zones could be distinguished based on palaeontological and geochemical results at the badenian sarmatian boundary faunal diversity decreased markedly in the lower zone a transgressive event culminated in a seawater incursion into the semi open basin system of the central paratheys stable bottom water temperature similar to 15 degrees c and variable salinites 20 22 are estimated for the early sarmatian sea the faunal changes notably a strong reduction in biodiversity occuring at the boundary between the lower and the middle zone can be explained by a sea leval highstand with dysoxic conditions a relative sea level fall is documented at the end of this middle zone after a short regressive event a marine connection between the paratethys and mediterranean was established at the beginning of the upper zone this is indicated by an increased microfaunal diversity and the re appearance of marine bademan ostracods and foraminifera which are completely absent from the older samatian series during the upper zone the temperatures and salmities are estimated to have fluctuated from 15 degrees c to 21 degrees c and from 15 parts per thousand to 43 parts per thousand respectively

modeling soil genesis at pedon and landscape scales achievements and problems modeling soil evolution is an important step towards understanding the complexity of the soil system and its interaction with the other systems the major challenge confronted by pedologists until now is the ability to develop models capable of describing the complete complexity of the soil system this paper presents the state of art overview of such a soil evolution model soilgen its applications and limitations in addition the paper gives an overview of how the soilgen model may be linked to landscape evolution models to model soilscape development soilgen is a mechanistic pedogenetic model in which soil forming processes such as clay migration decalcification carbon cycling bioturbation physical and chemical weathering coupled with water flow are simulated at multi millennium time scale the model has been calibrated and undergone extensive field testing giving reasonable results at both pedon and landscape scales however discrepancies between observed and simulated soil properties such as base saturation bs cation exchange capacity cec and ph have been reported these have been attributed partly to simplification of soil forming processes particularly in the weathering and chemical systems there is therefore a need to extend the description of chemical and weathering systems in the soilgen model these extensions will not only improve model performance but will also enlarge its application range in simulating the genesis of typical features of more than half of the wrb reference soil groups we also note here that although landscape evolution models have been successfully applied to model soil production and distribution simplified and or incomplete description of soil forming processes remain major limitations we therefore add to the voices in scientific literature calling for integration of pedon and landscape scale models in addition there is critical need for high quality chronosequence climosequence and toposequence profile datasets to enhance calibration and validation of soil evolution models

clay mineral formation in soils of two different chronosequences in the swiss alps two chronosequences of soils developed from postglacial tills at two different sites in the swiss alps were studied with respect to their soil mineralogy and chemistry the age of these soils ranged between 0 and 11 500 years the parent material for both chronosequences was similar but differences were found in the clay fraction within the considered time span podzols developed at both sites however at one site already after about 3000 years and at the other a few years later especially trioctahedral minerals were strongly weathered within the time span of about 11 000 years smectite and regularly interstratified dioctahedral mica smectite could be found in the most weathered horizons at one site the origin of smectite could be traced back to both chlorite and trioctahedral mica which supports the fact that smectite is the end product of chlorite alteration and regularly interstratified mica smectite or even smectite the end product of mica weathering in strongly leached and acidified horizons at the other site smectite was already present in the parent material most presumably due to hydrothermal formation during the first 500 years of soil formation a kind of retrograde podzolisation was observed leading to the elimination of this smectite within the same time increased amounts of dioctahedral minerals were formed and after 11 000 years a small proportion of pedogenic smectite was discernible again main clay mineral transformations occurred at both sites within the first 3000 years of soil development weathering and transformation reactions were most advanced in the e horizon being almost complete after 3000 years at one site the presence of significant amounts of chlorite and or a minimal content of mica of ca 5 seems however to be compulsory in order to detect low charge expandable minerals already after a 3000 year duration of soil formation in the alps otherwise smectite formation is retarded

the rhine linth glacier in the upper wurm a model of the last alpine glaciation abstract the wurmian glaciation of the alpine foreland has been reconstructed in different phases as a result of investigations in the rhine bodan region as well as in the linth area the whole high glacial is divided in four main phases ice advance into the piedmont basins building up of the foreland glaciation high stages and retreat into the inner alps this epoch took up perhaps less than 12 000 years during the period of building an average increase of ice thickness of about 12 cm per year was sufficient to form an extensive foreland glacier within 5000 7000 years the snow lines of the stades of the piedmont glaciation as well as of the local glaciers are calculated snow lines at about 1500 m a s l led to an inner alpine ice build up and an advance of glaciers towards the piedmont basins to produce the foreland ice sheet low snow lines of 900 1000 m a s l were necessary an interstadial phase before the maximum glaciation is evidenced by sediment sequences and a 14c date of 22 100 bp the chronology of ice retreat after 18 ka bp is still uncertain

carbon and oxygen isotope composition of nautilus macromphalus a record of thermocline waters off new caledonia abstract this study investigates the controls on the stable isotope composition of shell nacreous layer of a modern nautilus macromphalus from new caledonia closely spaced samples were taken both along growth lines isochrons and growth axis time series carbon isotope compositions 13 c 0 3 to 1 pdb of the shell decrease in the domains of maximal growth 0 3 and muscle insertion 0 4 maximal 13 c variations of about 1 are recorded in time series a global ontogenetic decrease of 13 c values is observed for both dorsal and ventral areas 0 4 to 0 8 and can be ascribed to a metabolic effect with age or to changes in the food source by contrast oxygen isotope compositions are quite constant 1 1 18 o

albeluvisol development with time in loamy marine sediments of southern norway abstract this paper reports a study on soil development in loamy marine sediments on both sides of the oslofjord vestfold ostfold this region has been subject to steady glacio isostatic uplift during the whole holocene hence land surface age continuously increases from the coast inland several sea level curves based on radiocarbon datings enable estimation of land surface age for all locations clay illuviation starts in less than 1650 years e horizons become lighter with age but their lower boundary stays around 40 cm for more than 10 000 years albeluvic tongues develop between 4600 and 6200 years initially they form along intersections of cracks as preferential flow and leaching along the cracks continues the tongues increase in length and width progressively consuming the prisms between the cracks in the upper bt horizon the fe d fe t ratios weighted means of the upper meter show a clear linear increase with soil age and may be used for pedo dating i e for estimating the ages of non dated land surfaces covered with similar sediments in contrast the logarithmic decrease of base saturation and ph with rapid changes in the first time but only very slight changes between 2000 and 10 000 years makes these parameters unsuitable for pedo dating

iron oxides and clay minerals within profiles as indicators of soil age in northern italy abstract nine profiles representing the alfisol inceptisol and entisol orders were sampled on three terraces forming a chronosequence total iron dithionite extractable iron and oxalate extractable iron were determined for all horizons of all profiles and the clay mineralogy for horizons of three profiles the percentage of total fe fet extracted by dithionite fed increased with age of terraces as did the difference between fed and feo oxalate extractable analysis of variance anova of the horizon data showed that the ratios fed fet and fed feo fet were closely related to the ages of the terraces clay minerals were also related to terrace ages with 2 1 minerals dominant in the profiles on the youngest and mixed layer minerals and kaolinite more abundant in profiles on the older terraces

mollusc and brachiopod skeletal hard parts intricate archives of their marine environment the biogenic carbonate hard parts of fossil bivalves cephalopods and brachiopods are among the most widely exploited marine archives of phanerozoic environmental and climate dynamics research the advent of novel analytical tools has led many workers to explore non traditional geochemical and petrographic proxies and work performed in neighbouring disciplines sheds light on the complex biomineralization strategies applied by these organisms these considerations form a strong motivation to review the potential and problems related to the compilation and interpretation of proxy data from bivalve cephalopod and brachiopod hard parts from the viewpoint of the sedimentologist and palaeoceanographer specific focus is on the complex biomineralization pathways of a given dissolved ion or food particle from its aquatic environment via the digestion and biomineralization apparatus in molluscs and brachiopods and its incorporation into a biomineral given that molluscs and brachiopods do not secrete their hard parts from seawater but rather from their mantle and periostracum this paper evaluates differences and similarities of seawater versus that of body fluids cephalopods bivalves and brachiopods exert a strong biological control on biomineralization that to some degree may buffer their shell geochemistry against secular changes in seawater chemistry disordered amorphous calcium carbonate precursor phases later transformed to crystalline biominerals may be significant in carbonate archive research due to expected geochemical offset relative to the direct precipitation of stable phases a reasonable level of understanding of the related mechanisms is thus crucial for those who use these skeletal hard parts as archives of the palaeo environment the impact of what is commonly referred to as biological factors on the geochemistry of mollusc and brachiopod hard parts is explored for conventional isotope systems such as carbon oxygen strontium and traditionally used element to calcium ratios in particular the often used 13ccarb or the mg ca and sr ca elemental proxies are fraught with problems an interesting new research field represents the analysis calibration and application of non traditional proxies to mollusc and brachiopod hard parts examples include the carbonate clumped isotope 47 approach and the analysis of the isotopes of ca mg n li s or element to ca ratios such as li ca or b ca and rare earth elements based on considerations discussed here a series of do s and don ts in mollusc and brachiopod archive research are proposed and suggestions for future work are presented in essence the suggestions proposed here include experimental work also field experiments making use of recent archive organisms or where possible a reasonable recent analogue in the case of extinct groups moreover the detailed understanding of the architecture of mollusc and brachiopod hard parts and their ultra structures must guide sampling strategies for geochemical analyses where feasible a detailed understanding of the diagenetic pathways and the application of multi proxy and multi archive approaches should form the foundation of fossil carbonate archive research the uncritical compilation of large data sets from various carbonate shelled organisms collected at different locations is not encouraged

c and o isotope compositions of modern fresh water mollusc shells and river waters from the himalaya and ganga plain the aim of this paper is to unfold the relationship between the o and c isotope compositions of modern fresh water mollusc shells and water in order to refine the basis of interpretation for paleoenvironnemental reconstruction in the sub himalayan river basins large number of mollusc shells and associated host water from both running water and closed body of water were analysed including intra shell variability in a few cases the o isotopic compositions of river waters in the himalaya and ganga plain have a large range from 18 in the north of the high range up to 8 to 4 in the ganga plain 18o of rivers are also seasonally variable especially in foothills rivers whereas the seasonal contrast is smoothed out for the main himalayan rivers having large catchments o isotopic compositions of bulk shells aragonite vary between 15 and 5 average 18oara values are consistent with precipitation at equilibrium with host waters at a temperature range of 20 25 c suggesting that shell growth may be favoured during non monsoon conditions shells collected along the main himalayan rivers have 18o values uniformly distributed within 11 and 6 reflecting the minimal seasonal contrast shown by these rivers in contrast o isotopic compositions of shells from foothills rivers vary only by 4 this shows that depending on the type of river where the molluscs grow the information in term of 18o amplitude will be different for identical climatic conditions in closed or pond water bodies significant enrichment in 18o due to evaporation is observed the c isotopic compositions of river dissolved inorganic carbon dic decrease downstream from 0 to 10 reflecting input of soil derived alkalinity and plant productivity in the river 13c of shells are systematically lower than compositions calculated for equilibrium with river dic indicating that in addition to dic a significant fraction of carbon is derived from metabolic sources intra shell 13c are stable compared to the seasonal variability of dic suggesting that the pool of organic carbon changes throughout year

the pedological heritage of the dolomites northern italy features distribution and evolution of the soils with some implications for land management abstract since 1997 the department of environmental sciences of ca foscari university of venice has undertaken numerous research projects aimed at deepening understanding of pedogenic processes in the dolomites and at highlighting the fundamental contribution that soil science can give to the conservation of natural resources and achieve sustainable management of mountain ecosystems a total of several hundred profiles have been described analyzed and mapped this paper reports the results from the analysis of pedo environmental characters of profiles developed from different parent materials at altitudes between 1300 m and 2900 m and in different conditions of slope exposure and vegetation cover soil forming factors landforms and land surfaces have been interpreted to understand the soil landscape in the mapped areas and to develop a qualitative model of soil geography into the dolomites scenery the application of land evaluation methods in some of the investigated territories that are subjected to intensive tourist fluxes revealed some criticisms collected results also highlighted the high environmental heterogeneity of soils of the dolomites

seawater temperature records from stable isotopic profiles in the shell of modiolus modiolus abstract the hypothesis that the sea urchin disease which devastated populations along the atlantic coast of nova scotia in 1980 83 is temperature related requires a record of bottom seawater temperatures over this period a time series of 18o values from two modiolus shells collected in a cove in nova scotia were used to reconstruct bottom water temperatures and as an independent method to age the mussels a fine scale of resolution was achieved with up to 15 discrete samples per year of shell deposition records from two shells showed similar trends the 18o values of the shells clearly tracked seasonal temperatures they suggested that bottom seawater temperatures were not unusually warm at this site in 1980 the year in which the sea urchin disease was first noticed ages of mussels determined from the oxygen isotope record were consistent with those estimated from annual growth lines on the shells

ontogeny and habitat change in mesozoic cephalopods revealed by stable isotopes δ18o δ13c abstract stable isotope 18 o and 13 c ratios were measured in successive aragonitic shell sequences of ammonoids class cephalopoda to determine whether their depth distributions changed within ontogeny and whether stable isotope values differ in various morphological groups e g leiostraca vs trachyostraca we concentrate mainly on 18 o for temperature results and added 13 c data to obtain information on the ontogenetic history for which full spiral measurements were undertaken for the first time to obtain valid stable isotope data from ammonoid shells we measured ontogenetic sequences full shell within different genera data sets from the jurassic cadoceras and cretaceous hypacanthoplite s nowakites were chosen due to the pure primary aragonitic shell preservation the study was designed to extract better information on the habitat and life cycle of fossil cephalopods e g ammonoids in comparison with recent cephalopods e g nautilus spirula sepia possessing equivalent or comparable hard parts the data from three genera suggest different modes of life in at least two morphological groups we detected and established two main groups with different ontogenetic strategies based on the 18 o data the wcw type warm cool warm type of cadoceras resembles strategies in nautilus and sepia which migrate from shallow into deeper environments and back in ontogeny wc type warm cool type and the cw type cool warm type of hypacanthoplites resembling the first two migration phases of spirula cwc type which migrates from deeper into shallower and back again into deeper habitats the main three phases revealed by both 18 o and 13 c data sets most probably reflect diet changes in juvenile to mid aged individuals followed by a habitat change for spawning adults in cadoceras the temperatures range from 21 2 c for juveniles down to 12 1 c for mid aged individuals and back up 16 9 c in adults the cw type strategy of hypacanthoplites involves a temperature range of 22 8 c to 28 9 c the respective mean values are 24 2 c juveniles 25 8 c middle phase and 27 8 c adults the 13 c values also revealed three ontogenetic stages in cadoceras and hypacanthoplites including two major shifts from positive to negative and from negative to positive values which probably correspond to sexual maturation the initiation of reproduction and concomitant changes in diet the presented data combined with previous ontogenetic studies e g stable isotopes on spirula nautilus and sepia can be used as proxies to directly correlate the habitats and ontogeny of recent and fossil cephalopods

evaluation of three methods for estimating the weathering rates of base cations in forested catchments abstract this paper investigates three techniques that are commonly used to generate estimates of base cation bc weathering rates i e the profile mass balance pedon the watershed input output budget watershed and the profile model model these methods were compared for their relative performance in estimating bc weathering rates for 21 watersheds located in southern quebec that vary with respect to hydro climatic conditions soil properties and forest cover average total bc weathering rates for the 21 watersheds were 0 41 0 09 se 1 20 0 17 and 1 71 0 22 kmol c ha 1 yr 1 for pedon watershed and model respectively passing and bablok regression analysis demonstrated good agreement between watershed and model regression formula watershed 0 08 0 74 model with 95 ci for intercept 1 13 0 25 and for slope 0 40 1 43 while poorer agreements were observed between these two methods and pedon contrary to the watershed and the model methods bc weathering rates obtained with pedon were not significantly associated with the spatial variation of the soil calcite content and of the size of the soil exchangeable bc pools we hypothesized that in the calcite containing watersheds the performance of pedon was negatively impacted by environmental conditions that favored the partial dissolution and leaching of the calcite contained in the initial parent material including in the material situated at the base of the profile c horizon

stable isotope data δ18o δ13c of the ammonite genus simbirskites implications for habitat reconstructions of extinct cephalopods abstract the accurate habitats of the extinct ammonites and belemnites are largely unknown most ammonites are thought to have had a pelagic lifestyle while belemnites are often considered to have dwelled in deeper colder waters stable isotope analysis 18o 13c provides a useful method to reconstruct the habitats of these two groups of extinct cephalopods but is at the same time limited by various unknowns including the isotopic composition of the past seawater vital effects and diagenesis in this paper stable isotope data from 12 ammonite shells simbirskites spp from the upper hauterivian of the lower saxony basin northwest germany are presented ontogenetic isotope profiles have been obtained from six of these shells in order to reconstruct habitat changes during their lifetime these new ammonite data are combined with published stable isotope data from belemnites hibolithes jaculoides and tex86 palaeotemperature estimates from the same section the combination of isochronous ammonite and belemnite stable isotope data shows that the resulting values of both groups go along with each other calculated palaeotemperatures of the two groups differ by 5 10 c with belemnites always showing the colder temperatures all juvenile shells show an increase of the 13camm to more positive values throughout their ontogeny they are stable in an adult shell fragment the incorporation of carbon isotopes in the ammonite shell therefore correlates with ontogeny and is influenced by metabolic effects probably linked to the shell growth rate the isotope profiles further suggest vertical habitat changes during the ontogeny of the ammonites indicating that the 13camm values might record a combination of environmental and metabolic signals taking into account studies on oxygen isotope fractionation of recent aragonitic and calcitic mollusc shells a similar pelagic habitat is proposed here for both ammonites and belemnites

deciphering kinetic metabolic and environmental controls on stable isotope fractionations between seawater and the shell of terebratalia transversa brachiopoda this study presents carbon and oxygen stable isotope data obtained from high resolution sampling 500 m of the brachiopod terebratalia transversa from the san juan islands washington state usa the aim of this study is to unravel the respective effects of physiological and environmental controls on the stable isotopic composition of brachiopod shell calcite based on an sem study of the shell a three dimensional sampling was performed in order to investigate carbon and oxygen isotope variations along isochrons and ontogenetic transects the primary as well as the outer part of the secondary shell layer display large and variable isotopic offsets as high as 7 for 13c and 6 for 18o relative to expected equilibrium values the significant positive correlations between 18o and 13c values indicate that the isotopic compositions of these shell domains are mainly controlled by kinetic isotope fractionation effects the ontogenetic 13c and 18o variations can be used to establish a growth curve of the studied specimen whose age is estimated close to 8 years the extent of apparent o 18 disequilibrium observed in this study is about as large as any yet measured in any organism which makes this brachiopod an interesting and important case the carbon and oxygen isotope compositions increase from the outer towards the inner part of the secondary layer where they reach values of 0 0 8 and 0 8 to 0 2 respectively corresponding calculated temperatures are between 12 and 13 8 c and fall in the range of seawater temperatures recorded off the san juan islands 7 13 c these results suggest that the calcite fibres were secreted more and more slowly during the thickening of the shell throughout the animal s life finally approximating isotopic equilibrium this study illustrates that the stable isotopic composition of the modern brachiopod t transversa is predominantly influenced by kinetic fractionation and to a minor degree by metabolic effects except for the innermost part of the shell the measured isotope ratios do not reflect environmental conditions during shell precipitation it remains to be tested by comparable studies whether other modern brachiopod species or even fossil brachiopods reflect comparable fractionation effects these results point out the need for re examination of paleozoic oceanographic conditions

the shell of the queen scallop aequipecten opercularis l as a promising tool for palaeoenvironmental reconstruction evidence and reasons for equilibrium stable isotope incorporation abstract the queen scallop aequipecten opercularis has been an important part of the marine fauna of the northeast atlantic region since the miocene and is a suitable candidate for palaeoenvironmental studies using stable isotopes modern shells were investigated to determine if carbonate is precipitated in isotopic equilibrium in this species and to confirm that growth continues through the year specimens of a opercularis were cultured under monitored semi natural conditions over an autumn winter period and the analyses of these specimens were supplemented with isotope data from preserved indigenous north sea specimens the results indicated that the cultured specimens grew in relatively low temperatures that oxygen isotopes of shell exterior carbonate were precipitated in isotopic equilibrium and that a large proportion of the ambient temperature range was recorded in shell carbonate the indigenous north sea specimens exhibited a good correspondence to predicted oxygen isotope values for summer the isotopic record related to winter was however somewhat truncated due to growth decelerations in the specimens carbon isotopes of shell exterior carbonate were calculated as being derived primarily from external sources and showed comparatively little influence from metabolically derived carbon this suggests that carbon isotopes were at least close to equilibrium with ambient waters the limited incorporation of metabolic products suggests that a opercularis would be a good monitor of changing carbon isotope ratios in seawater dissolved inorganic carbon the occurrence of equilibrium shell precipitation is explained using a pteriomorph shell calcification model which proposes that transport of ions through the periostracum caused the composition of the extrapallial fluid to be effectively the same as seawater carbonate secretion is therefore not influenced significantly by biological vital effects

the long lived mollusc arctica islandica a new paleoceanographic tool for the reconstruction of bottom temperatures for the continental shelves of the northern north atlantic ocean the carbonate shell of the bivalve arctica islandica has been recognized for more than a decade as a potentially important marine geochemical biorecorder owing to this species great longevity 200 years and wide geographic distribution throughout the northern north atlantic ocean a region vital to global climate and ocean circulation however until now this potential has not been realized owing to the difficulty of precisely sampling the shell of this slow growing species using newly available automated microsampling techniques combined with micromass stable isotope mass spectrometry a stable oxygen isotope record 1956 1957 and 1961 1970 has been obtained from a live captured 38 year old a islandica specimen collected near the former position of the nantucket shoals lightship 41 n 69 w the shell s 18o signal is compared with an expected signal derived from ambient bottom temperature and salinity data recorded at the lightship for the same period the results show that a islandica s 18o record 1 is in phase with its growth banding confirming the annual periodicity of this species growth bands 2 is in oxygen isotopic equilibrium with the ambient seawater 3 shows a consistent shell growth shutdown temperature of 6 c which translates into an 8 month may december shell growth period at this location and 4 records the ambient bottom temperature with a precision of 1 2 c these results add important information on the life history of this commercially important shellfish species and demonstrate that a islandica shells can be used to reconstruct inter and intra annual records of the continental shelf bottom temperature

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

quantitative aspects of carbonate leaching of soils with differing ages and climates abstract carbonate leaching rates in several soils in switzerland and in the lake constance region were calculated and related to landscape development the leached depth of the soil the carbonate content and the soil density profile are sensitive to soil age a first database of carbonate leaching and its relationship to soil age is presented a simple relationship between the amount of precipitation and carbonate losses was found water draining from calcareous soils from subarctic to temperate areas was usually close to equilibrium with calcite and dolomite thus the annual amount of rainfall and consequently the percolation are the most important factors in carbonate leaching the influence of temperature is comparatively low carbonate dissolution rates amounted to approximately 1 7 3 0 mol m 2 year 1 if they are referred normalised to 1000 mm soil water fluxes soils on coarse parent material may have slightly lower carbonate dissolution rates in the order of approximately 1 7 2 2 mol m 2 year 1 normalised to a 1000 mm output while other sites with smaller grain sizes had slightly higher dissolution rates 2 2 3 0 mol m 2 year 1

the fidelity of oxygen and strontium isotope values from shallow shelf settings implications for temperature and age reconstructions abstract the oxygen and strontium isotopic ratios of marine carbonates are widely employed to derive paleotemperature and age respectively while open ocean samples are the standard source for these measures shelf settings can also provide detailed records however the implementation of shelf data for these purposes has been hindered by the perception that local environmental conditions such as freshwater influx confound regional and global signals here we directly evaluate this concern by assessing the spatial variability in the isotopic composition of biogenic carbonate precipitated along the depositional strike of an inner shelf environment data are derived from mollusc shells collected from a stratigraphically restricted transgressive unit in the early eocene 55 ma of the us gulf coastal plain gcp lithofacies and fossil assemblages suggest that an estuary was present in the westernmost study region whereas more typically marine facies predominated elsewhere isotopic composition varies predictably with paleoenvironmental setting shells from the estuary have 18o values and 87sr 86sr ratios that reflect high freshwater input specimens in the eastern gcp however from within and between outcrops separated by up to 400 km all yield similar results serial microsampling reveals congruence not only in mean 18o values but also in winter and summer extremes estimated paleotemperatures mean annual temperature of 26 c agree well with proxy and model evidence for the early eocene and the gcp and 87sr 86sr ratios are consistent with the established early eocene seawater ratio the fidelity of isotopic values relative to environment indicates that shallow shelf records have much to contribute to studies of ancient climate and ocean chemistry

climatic fluctuations and seasonality during the late jurassic oxfordian early kimmeridgian inferred from δ18o of paris basin oyster shells abstract oxygen isotope data from biostratigraphically well dated oyster shells from the late jurassic of the eastern paris basin are used to reconstruct the thermal evolution of western tethyan surface waters during the early oxfordian early kimmeridgian interval seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy isotope analyses were performed on non luminescent parts of shells n 264 intra shell 18 o variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell the sinusoidal distribution of the 18 o values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra shell variability reflects seasonal variations of temperature and or salinity average amplitudes of about 5 c in shallow water environments and of about 2 3 c in deeper offshore environments are calculated these amplitudes reflect minimum seasonal temperature variation our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite 18 o data and are in better agreement with paleontological data more specifically a warming trend of about 3 c is reconstructed for oceanic surface waters during the early to middle oxfordian transition with maximum temperatures reaching 24 c in the transversarium zone late middle oxfordian from the transversarium zone to the bimmamatum zone a cooling of about 7 c is indicated whereas from the bimmamatum zone temperatures increased again by about 7 c to reach 24 c in average during the cymodoce zone early kimmeridgian

warm palaeotemperatures from high late jurassic palaeolatitudes falkland plateau ecological environmental or diagenetic controls abstract oxygen and carbon isotopes have been determined from late jurassic oxfordian tithonian belemnites and inoceramid bivalves from two deep sea drilling project dsdp sites located on the falkland plateau mean belemnite 18o values derived from well preserved skeletal material were 1 29 from dsdp site 330 and 1 45 from dsdp site 511 assuming a seawater smow value of 1 0 mean palaeotemperatures calculated from the oxygen isotopic composition are 17 2 c and 17 9 c respectively the inoceramid bivalves yielded much lighter 18o values mean 3 58 petrographic and geochemical evidence points to the inoceramid bivalves being altered by diagenesis which accordingly accounts for the observed differences in isotopic values vital effects or the importation of belemnites or inoceramids from another area are considered not to account for the observed isotopic trends the palaeotemperatures interpreted from the belemnites are significantly warmer than other recent estimates of late jurassic temperature from oxygen isotope studies and climate model predictions from similar southern palaeolatitudes we suspect our apparent warmer temperatures are because of a combination of increased freshwater runoff depleting surface waters with respect to 18o and related to the semi enclosed nature of the depositional basin retaining warmth relative to the open ocean of similar latitudes

miocene stable isotope record a detailed deep pacific ocean study and its paleoclimatic implications deep sea drilling project site 289 in the western equatorial pacific has yielded an extremely detailed record of the carbon and oxygen isotopic changes in the miocene deep ocean the isotopic record reflects major changes in paleoclimate and paleoceanography probably dominated by a major phase of antarctic ice cap growth the transition from a relatively unglaciated world to one similar to today occurred between 16 5 x 10 6 and 13 x 10 6 years before the present with the greatest change occurring between approximately 14 8 x 10 6 and 14 0 x 10 6 years before the present

reconstruction of late bajocian bathonian marine palaeoenvironments using carbon and oxygen isotope ratios of calcareous fossils from the polish jura chain central poland abstract oxygen and carbon isotope analyses were carried out on upper bajocian bathonian calcitic belemnite rostra and oyster shells as well as aragonitic ammonite nautiloid and trigoniid shells from the ore bearing czestochowa clay formation in south central poland all samples were studied by means of cathodoluminscence microscopy trace element x ray and scanning electron microscope sem analysis in order to select best preserved material sem studies allowed classifying some aragonitic ammonite and nautiloid shells 99 aragonite as diagenetically altered average 18o values of oysters belemnites and trigoniids translate into relatively low palaeotemperatures of 10 1 9 2 and 7 4 c respectively the comparable 18o values of bivalves and belemnites indicate that belemnites had a nectobenthic lifestyle and did not record surface water temperatures the ammonite fauna is interpreted to have been nektonic however palaeotemperatures derived from ammonite 18o around 18 6 c may be overestimated due to a lower than normal marine salinity of surface waters the reduced salinity is inferred as well from sedimentological observations and faunal composition the obtained 18o values indicate cool climatic conditions during the late bajocian bathonian in south central poland which may have been linked with the occurrence of a cold climatic episode despite the fact that all studied shells were not precipitated in carbon isotope equilibrium with ambient waters the 13c shell values enabled us to roughly estimate isotope composition of dissolved inorganic carbon dic in the late bajocian bathonian sea of south central poland water 13cdic values calculated from ammonite 13c are lower in comparison to 13cdic values calculated from oyster and belemnite carbon isotope ratios which in conjunction with ammonite 18o values indicates lower salinity of surface or shallow near coastal waters

high northern palaeolatitude jurassic cretaceous palaeotemperature variation new data from kong karls land svalbard abstract the traditional view of warm equable global climates in the mesozoic with weakly developed latitudinal temperature gradients has been challenged by several recent studies however reliable high palaeolatitude palaeotemperature data is still rare in this study palaeotemperature data based on oxygen stable isotope palaeothermometry of well preserved mid jurassic to lower cretaceous belemnites from kong karls land svalbard are presented these data show cool high latitude marine isotopic palaeotemperatures for endemic species during the lower to mid valanginian 7 7 c which may be compatible with the formation of high latitude ice middle bathonian to kimmeridgian samples give warmer isotopic palaeotemperatures 9 4 c whilst samples from the aalenian to bajocian give isotopic palaeotemperatures which are warmer still 12 7 c comparison of the callovian temperatures with those from a mid latitude location shows them to be warmer than would be expected if previous latitudinal temperature gradients are correct this may be due to the ameliorating effect of oceanic heat transport pole wards from the panthalassa ocean via the south anyui ocean

oxygen isotopes from limpet shells implications for palaeothermometry and seasonal shellfish foraging studies in the mediterranean abstract limpet shells are common components of many archaeological sites in the mediterranean to test whether 18o values from archaeological patella caerulea shells can serve as a reliable palaeothermometer for the mediterranean and a reliable archive of season of collection information we collected live p caerulea from eight mediterranean locations in croatia israel libya malta tunisia and turkey shell growth patterns were studied in section and samples for oxygen isotope analysis were milled from the shells and used to calculate sea surface temperature sst as with other species of limpet sst reconstructed from p caerulea 18o values were lower than expected from observational records however when a correction factor of 0 72 was applied the shells recorded sst within the range of instrumental sst sst calculated from 18oshell values of the most recently formed shell portion of monthly collected shells from one site in libya were strongly and significantly correlated with instrumental sst in the region r2 0 95 oxygen isotope curves from individual shells sampled at high resolution from each of the study sites across the mediterranean exhibited sinusoidal patterns annual growth lines correlated with the lowest 18oshell values and were thus formed in summer however shell growth rates varied markedly between the sites some sites with larger shells recorded less than a year of growth in broad highly irregularly shaped increments at other sites medium sized shells recorded several years of growth with clear regular growth increments a sclerochronological approach can therefore be used to pre screen limpet shell sections before geochemical sampling the 18oshell values from shells sampled at high resolution recorded the full seasonal range of instrumental sst at each collection site this reinforces the potential of this species as one of the few sub seasonal resolution palaeoenvironmental archives in the region additionally the pattern of 18oshell variation from the last formed shell portion was studied to determine whether accurate season of collection information could be identified from p caerulea shells the correct season was interpreted 80 of the time indicating that this species is a good candidate for seasonal shellfish foraging studies using archaeological shells

oxygen and carbon isotope compositions of middle cretaceous vertebrates from north africa and brazil ecological and environmental significance in order to investigate mid cretaceous terrestrial climates of low paleolatitudes moroccan tunisian and brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates delta 18 o p and carbonates delta 18 o c delta 18 c c at each site coexisting theropod dinosaurs titanosaurid sauropods pterosaurs crocodilians turtles and fish have distinct delta 18 o p and delta 18 c c values reflecting their ecologies diets and foraging environments oxygen isotope compositions of surface waters delta 18 o w estimated from turtle and crocodile delta 18 o p values range from 5 0 1 0 parts per thousand to 2 4 1 0 parts per thousand which do not differ from mean annual rainwater values occurring today under inter tropical sub arid to arid climates high water temperatures ranging from 21 6 degrees c to 34 2 degrees c deduced from fish delta 18 o p values are in agreement with those published for mid cretaceous low latitudes temporary or seasonal droughts are inferred from high delta 18 o p values of lungfish teeth even though lower reptile delta 18 o p values suggest the use of distinct and most likely larger or regularly renewed bodies of water environmental conditions of the studied low latitude regions during the aptian cenomanian interval were somewhat similar to those experienced today under semi arid to arid tropical or equatorial climates but with higher mean surface temperatures than present day ones

stable carbon and oxygen isotope compositions of invertebrate carbonate shells and the reconstruction of paleotemperatures and paleosalinities a case study of the early pleistocene of rhodes greece abstract the coastal sediments of rhodes in the eastern mediterranean have recorded transgression regression cycles that took place during the early pleistocene the sedimentary deposits from the kritika member of the rhodes formation consist in conglomerates sandstones siltstones and clays deposited in brackish to shallow marine environments faunal associations are dominated by molluscs and reveal rapid ecological changes carbon and oxygen isotope ratios of aquatic skeletal carbonates show that these ecological changes were most likely driven by large salinity changes while water temperature remained rather constant at about 22 0 1 5 c the tectonic activity of the island rather than glacio eustatic variations of climatic origin is advocated to be responsible for the ecological and salinity changes and sea level variations recorded in the sedimentary sequence

weathering mineralogical evolution and soil organic matter along a holocene soil toposequence developed on carbonate rich materials a toposequence of holocene soils located between 1100 2400 m asl in the italian alps served as the basis for the following analyses the weathering of limestone and dolomite the calculation of mass balances understanding the formation of pedogenic fe and al the determination of soil mineral and clay mineral reactions and transformation and the measurement of accumulation and stabilisation mechanisms of soil organic matter leaching of carbonates is most intense at the lower elevations although calcite and dolomite have a higher solubility at low temperatures the pco2 in the soil is higher at lower elevations and weathering is driven mainly by carbonic acids at higher elevations organic acids appear to determine the mineral transformations and weathering reactions to a greater extent this suggests that two very different weathering regimes carbonic and organic acid weathering exist along the toposequence the transformation of mica into vermiculite is the main process in both the clay and fine earth fraction weathering of silicate minerals started even before the carbonates had been completely removed from the soils the transformation mechanisms of silicate minerals in the a and o horizon at higher elevations was at least as intensive as that at the climatically warmer sites the neoformation of pedogenetic clays at climatically cooler sites was slightly greater than that at the warmer sites however the formation rate of secondary fe and al phases was more pronounced at lower elevation which means that this process seemed to be driven dominantly by carbonic acid weathering of primary minerals soil organic matter som abundance in the mineral soil is nearly 15 kg m2 at all sites and surprisingly no climate driven effect could be detected in general the preservation and stabilisation of som was due to poorly crystalline al and fe phases and vermiculite regardless of some variations in the composition of the parent material varying calcite dolomite ratio

exploring aberrant bivalve shell ultrastructure and geochemistry as proxies for past sea water acidification throughout much of earth s history marine carbonates have represented one of the most important geological archives of environmental change several pivotal events during the phanerozoic such as mass extinctions or hyperthermal events have recently been associated with ocean acidification nevertheless well defined geological proxies for past ocean acidification events are at best scarce here experimental work explores the response of bivalve shell ultrastructure and isotope geochemistry c 13 o 18 and mg 26 to stressful environments in particular to sea water acidification in this study the common blue mussel mytilus edulis was cultured from early juvenile stages to one year of age at four ph regimes ph nbs 72 to ph 80 shell growth rate and ultrastructure of mainly the calcitic portion of the shells were compared between experimental treatments specimens exposed to low ph environments show patches of disordered calcitic fibre orientation in otherwise well structured shells furthermore the electron backscattered diffraction analyses reveal that under acidified conditions the c axis of the calcite prisms exhibits a bimodal or multi modal distribution pattern similar shell disorder patterns have been reported from mytilids kept under naturally acidified sea water conditions in contrast this study found no evidence that different ph regimes affect shell carbon oxygen or magnesium isotope ratios based on these observations it is proposed that i stressful environments in this case low sea water ph predictably affect bivalve biomineralization patterns and ii these findings bear potential as a novel petrographic proxy for ancient sea water acidification an assessment of the applicability of these data to well preserved fossil shell material from selected time intervals requires additional work

ecological and paleoenvironmental information using stable isotope profiles from living and fossil molluscs stable oxygen and carbon isotopic profiles from recent specimens of spisula solidissima and placopecten magellanicus collected off the virginia coast are used to calibrate annual temperature controlled cycles in the 18o profile and shell growth characteristics the amplitude of the annual 18o cycles decreases with increasing water depth and may be used as a relative depth indicator the isotopic of profiles of two fossil specimens of pleistocene spisula are very similar in amplitude and character to modern analogues and verify the formation of annual growth increments in these fossil specimens offsets between the 18o profiles of the fossil and modern specimens are related to known temperature and ice volume effects during the late pleistocene and support the utility of mollusc isotope records as a stratigraphic tool carbon isotopic profiles from all specimens show light values in the spring and or fall associated with seasonal phytoplankton productivity offsets in the carbon isotopic composition between infaunal and epifaunal species may be related to sediment porewater geochemistry and oxidation of organic matter trends toward lighter 13c values through ontogeny suggest the effects of metabolic changes from a fast growing juvenile into a slower growing sexually mature adult anomalies in both the oxygen and carbon isotopic profiles identify the formation of minor shell growth increments as corresponding to hydrographic perturbations and to winter cold temperatures

stable isotope fractionation between mollusc shells and marine waters from martinique island abstract forty nine aragonitic and calcitic shells from 14 species of marine tropical molluscs bivalvia gastropoda polyplacophora and ambient waters from martinique have been analyzed for their carbon and oxygen isotope compositions mineralogy of shells was systematically determined by raman spectroscopy that reveals composite shell structures and early processes of diagenetic alteration in mangrove brackish waters result from the mixing between 89 1 of seawater and 11 1 of freshwater a hydrological budget quantified by both oxygen isotope and salinity mass balance calculations mollusc shells from the mangrove environment s 31 18 o 0 5 are characterized by mean 13 c values 1 2 lower than those 2 6 living in the open sea s 35 18 o 1 these low carbon isotope compositions result from the oxidation of organic matter into bicarbonate ions used in the building of mollusc shells the oxygen isotope compositions of the studied mollusc species are mainly controlled by the temperature and composition of seawater whereas the role of the so called vital effects is negligible contrasting with carbon isotopes variability in the 18 o values among and within species of mollusc shells is very low 1 0 15 for a given littoral environment using ambient temperatures of seawater 28 30 c oxygen isotope fractionations between all studied living species and environmental waters match those extrapolated from the fractionation equation established for molluscs by grossman and ku chem geol isot geosci sect 59 1986 59 in the range 3 20 c by analyzing calcite and aragonite layers from the same shell or by comparing shells from different species living in the same environment there is no evidence that oxygen isotope fractionation between aragonite and water differs from that between calcite and water on the basis of these results we conclude that the oxygen isotope compositions of shells from most fossil mollusc species are suitable to estimate past seawater temperatures at any paleolatitude

new research on the development of high resolution palaeoenvironmental proxies from geochemical properties of biogenic carbonates abstract geochemical signatures from biogenic carbonates are being increasingly employed as palaeoenvironmental proxies in turn many of these proxy archives including mollusc shells corals and otoliths have periodic growth structures which allow the reconstruction of chronologically constrained records of palaeoenvironmental variability at unparalleled high temporal resolution studying the growth and chemistry of these periodic growth structures is known as sclerochronology biogenic hard parts accumulate in geological or archaeological deposits and can be directly dated using radiometric and racemisation methods they therefore offer the opportunity for high resolution palaeoenvironmental reconstructions across many time intervals all over the globe such data are important for several reasons 1 understanding past climate and environmental change provides a means of contextualising current and future climate change and ecological disturbance 2 high resolution palaeoenvironmental records are essential for constraining testing and validating global and regional numerical climate models 3 palaeoenvironmental records from biogenic carbonates can provide an environmental framework from which to understand the behavioural changes and interactions of peoples with their environment however inter and intra species differences in growth rate physiology and environmental response can cause variations in the chemical profiles of biogenic carbonates before geochemical data is employed for palaeoenvironmental reconstructions it is thus necessary to examine modern specimens of the target species or related taxa to understand how geochemical variations are influenced by local environmental conditions kinetic and vital effects this allows the generation of quantitative and more reliable proxy records of environmental change this special issue brings together the latest research on palaeoenvironmental proxy development and validation in biogenic carbonates it includes studies on marine freshwater and estuarine organisms molluscs corals and echinoderms and on traditional as well as novel geochemical proxies the papers presented here include in situ field calibration studies laboratory growth experiments as well as methodological studies into the effects of sampling and pre treatment the geographical scope is broad encompassing both the northern and southern hemispheres including south africa south america australia asia the mediterranean sea and the north atlantic

origin age and transformation of chernozems in northern central europe new data from neolithic earthen barrows in sw poland abstract among the clay illuviated soils dominant in the loess belt in southern poland islands of chernozemic soils are distinguished by their spectacular agricultural productivity however those soils are not marked as chernozems phaeozems in european and world soil maps due to their common excessive wetness and doubts regarding their origin well preserved earthen barrows of the funnel beaker culture discovered recently in muszkowice sw poland offer a unique possibility of pedo archaeological reconstruction the first of such in poland of the pre and post neolithic development of soil cover in loess dominated areas and explanation of the existing differentiation of soil cover into neighbouring chernozems and retisols the buried chernozemic soil phaeozem in muszkowice started to develop in the late pleistocene period mean residence time of humus 12 670 13 000 cal bp until the burial ca 5480 5310 cal bp an at least 22 cm thick mollic horizon has developed with secondary carbonates accumulation at ca 80 cm the barrow mound soil constructed entirely of initially humus rich topsoil material has transformed into retisol with fully developed thick eluvial and illuvial argic horizons and still preserved a high content of humus in the barrow mound soil profile further the surrounding soils are entirely altered into retisols with secondary carbonates starting at 135 160 cm taking into account the palynological reconstruction from the nearest pollen profile in the loess covered area a crucial importance of the open canopy mainly oak forests is concluded for the persistence of chernozems under a temperate increasingly moist climate from the early holocene to the neolithic period in turn the close canopy broadleaf forests mainly beech are considered to be responsible for the rapid transformation of chernozems phaeozems into retisols luvisols in the late holocene chernozems have persisted and probably even rejuvenated only in the areas of permanent settlement since the neolithic until the present time where human activity farming pasturing has eliminated a continuous broadleaf beech close canopy forest cover

preservation of delta 18 o and delta 13 c in belemnite rostra from the jurassic early cretaceous successions stratigraphic collection of 263 belemnite rostra guards from jurassic to lower cretaceous sediments in the moscow area of russia northern germany england new zealand and morocco were analyzed to determine temporal variations in their delta 18 o and delta 13 c as a proxy for isotopic composition of surface seawater internal structures of the rostra were studied using cathodoluminescence and sem techniques their trace element fe mn mg and sr and the stable carbon and oxygen isotope compositions the average stratigraphic resolution is about 1 ma these samples represent a broad range of paleolatitudes and paleoceanographic settings ranging from 42 degrees n to 82 degrees s covering boreal to subtropical brackish to open marine shelf paleoenvironments the rostra originally contained domains enriched in organic matter that were later replaced by luminescent diagenetic calcite thereby generating an impression of seasonal growth rings diagenetic calcite accounts for up to 6 8 percent of the rostrum the trace element content of the rostra range from 227 to 3935 ppm for mg 379 to 1514 ppm for sr and up to 305 and 3662 ppm for mn and fe respectively however selective drilling of only primary calcitic domains resulted in 90 percent of all analyzed samples to fall within the range of trace element values typical for modern low mg calcite shells the chemical and textural data suggest that the primary calcite of the rostra is well preserved as is its isotopic signature the delta 13 c and delta 18 o measurements define oscillating temporal bands of about 3 to 4 per mil width around more or less modern marine values of 2 and 1 per mil respectively oxygen isotopes in the well preserved rostra most likely reflect temperature variations within a approximately 14 or 8 degrees c range the observed 3 to 4 per mil spread of values between contemporaneous specimens which is comparable to the scatter of data reported for modern low mg calcitic brachiopod shells probably reflects the diversity of local ecosystems although some of the spread may be due to real short term temporal variations within single biozones the delta 13 c values of the rostra define a band similar to that of the oxygen isotopes and the temporal oscillations of both isotope curves are commonly in phase the above dataset complemented by the results of jones jenkyns and hesselbo 1994 and jones and others 1994 yields a composite delta 18 o and delta 13 c variations in belemnite guards for the entire jurassic early cretaceous interval for delta 18 o the oscillating band indicates that the most negative values occur at times of independently postulated global and or regional anoxic events such as those in the toarcian and kimmeridgian as well as the aptian these oaes appear to be characterized by up to 10 degrees c higher seawater temperatures than the intervening background times the delta 13 c record shows 13 c depletion for the kimmeridgian event but enrichment for the other two suggesting that the delta 13 c temporal oscillations and oaes are not simply a reflection of surficial productivity due to operation of the biological pump but rather of changing oceanic circulation patterns due to variations in latitudinal surface temperature gradients

evolution of early cenozoic marine temperatures the equator to high southern latitude sea surface and vertical temperature gradients are reconstructed from oxygen isotope values of planktonic and benthic foraminifers for the following five time intervals late paleocene early eocene early middle eocene late eocene and early oligocene paleotemperatures are calculated using standard oxygen isotope temperature equations with adjustments to account for 1 variations in sea water 18o related to changes in global ice volume over time and 2 latitudinal gradients in surface water 18o these reconstructions indicate that sea surface temperatures sst of the southern oceans in the early eocene were as high as 15 c whereas temperatures during the late paleocene and early middle eocene reached maximum levels of 10 12 c by the late eocene and early oligocene high latitude sst had declined to 6 and 4 c respectively for most of the early paleogene low latitude sub tropical temperatures remained constant and well within the range of holocene temperatures 24 ndash 25 c but by the late eocene and early oligocene declined to values in the range of 18 to 22 c the late paleogene apparent decline in tropical temperatures however might be artificial because of dissolution of near surface foraminifera tests which biased sediment assemblages toward deeper dwelling foraminifera moreover according to recent plate reconstructions it appears that the majority of sites upon which the late eocene and early oligocene tropical temperatures were previously established were located either in or near regions likely to have been influenced by upwelling global deepwater temperature on average paralleled southern ocean sst for most of the paleogene we speculate based on the overall timing and character of marine sea surface temperature variation during the paleogene that some combination of both higher levels of greenhouse gases and increased heat transport was responsible for the exceptional high latitude warmth of the early eocene

from a black to a gray box a mass balance interpretation of pedogenesis we utilize chemical elements as tracers in a mass balance analysis that provides functional relationships among soil chemical composition bulk density and volume change in relation to parent material these analytical functions are based on the principle of conservation of mass and include a term quantifying mass flux into out of the soil and between horizons we apply the technique to the oldest member of a chronosequence developed on marine terraces in northern california it is an alfisol that evolved from beach sand to its present state nearly one third of its weight is composed of secondary clay minerals in about 240 ky aside from large increases in organic carbon desilication is the dominant factor in soil evolution 29 50 83 g cm 2 si was leached from the beach sand during pedogenesis the rate of desilication is roughly 2 1 t km 2 yr 1 0 21 g cm 2 ky 1 an order of magnitude slower than that implied by the si denudation rate calculated for the mattole river watershed weathering of primary minerals and synthesis of secondary minerals is relatively well advanced suggesting that the rate of desilication may be declining the local beach is composed of quartz and sodic plagioclase with smaller amounts of chlorite mica and kaolinite the soil has substantially different mineralogy sand is dominated by quartz and clay is dominated by kaolinite halloysite chloritic intergrades and gibbsite bases are also leached though the total mass was much less 57 2 55 g cm 2 of na in the beach sand was lost as plagioclase weathered by focusing on elemental and mineralogical gains and losses we emphasize the essential connection between the pedologic environment and the external hydrochemical environment

progressive and regressive soil evolution phases in the anthropocene soils have a substantial role in the environment because they provide several ecosystem services such as food supply or carbon storage agricultural practices can modify soil properties and soil evolution processes hence threatening these services these modifications are poorly studied and the resilience adaptation times of soils to disruptions are unknown here we study the evolution of pedogenetic processes and soil evolution phases progressive or regressive in response to human induced erosion from a 4000 year lake sediment sequence lake la thuile french alps erosion in this small lake catchment in the montane area is quantified from the terrigenous sediments that were trapped in the lake and compared to the soil formation rate to access this quantification soil processes evolution are deciphered from soil and sediment geochemistry comparison over the last 4000 years first impacts on soils are recorded at approximately 1600 yr cal bp with the erosion of surface horizons exceeding 10 t km 2 yr 1 increasingly deep horizons were eroded with erosion accentuation during the higher middle ages 1400 850 yr cal bp reaching 1000 t km 2 yr 1 and leading to the remobilization of carbonated and poorly weathered material hence rejuvenating soil development erosion exceeded the soil formation rate and constituted a regression in the development of soils the tolerable erosion limit is thus defined for erosion from 25 to 30 t km 2 yr 1 beyond this limit the sustainability of the agroecosystem is limited and ecosystem services decrease afterwards pedogenesis evolved again from progressive 700 300 yr cal bp to regressive 300 yr cal bp today phases erosion was less important during the last 700 years than during the middle ages but with the same weathering stages indicating that soils were deeply affected during the middle age and have yet not recovered our results highlight the importance of the human factor in the pedogenesis over last millennia and suggest that the studied agro ecosystem entered the anthropocene 1400 years ago

unraveling environmental histories from skeletal diaries advances in sclerochronology high resolution proxy archives from aquatic settings are essential to better understand processes and mechanisms of global change during the last decade it has become increasingly evident that calcified tissues of bivalve mollusks and cold water corals in particular can significantly increase our knowledge of seasonal to multi decadal paleoclimate and paleoenvironmental variability in the extratropical oceans and coastal marine settings daily tidal fortnightly and annual growth patterns of periodically formed skeletal hard parts provide a means to place the proxy record in a precise temporal context their extreme longevity coupled with the running similarity between growth increment time series of contemporaneous bivalves opens the possibility of constructing stacked chronologies covering centuries to millennia which provide information on decadal climate and environmental variability and magnitudes of climate variability through time a current major research focus is on how to translate geochemical properties of the skeletons into quantifiable environmental proxy data and how to eliminate the adverse influence of vital effects on the proxy records this special issue presents the most recent advances in the field of sclerochronology specifically calcified tissues of bivalve mollusks cold water corals and tropical shallow water corals the majority of the contributions deal with the potential reconstruction of temperature ph and productivity through the analysis of variable growth rates sr ca mg ca ba ca u ca li ca 13c 18o and 44 40ca four papers present composite chronologies of two long lived bivalve species and discuss inherent decadal climate variability and one study demonstrates that sclerochronology can shed light on socioeconomic patterns of past human populations as well as resource use and resource management by people

spatio temporal modeling of soil characteristics for soilscape reconstruction abstract full coverage maps for several specific soil characteristics were produced at particular time intervals over a time span of 12 716 years for a 584 km 2 large study area located in belgium the pedogenetic process model soilgen2 was used to reconstruct the evolution of several soil variables at specific depths in the soil profile at various point locations 96 in total the time span covered by the simulations encompassed the final part of the younger dryas and the holocene up till the present time series on climate organisms and groundwater table were reconstructed and supplied to the model as boundary conditions model quality optimization was performed by calibrating the solubility constant of calcite by a comparison of the simulated time necessary for decarbonization with literature values and evaluating the calibrated value over a wide range of precipitation surpluses representative for the regarded time period the simulated final state was evaluated against measurements collected in a database representing the historic state of the soil at 1950 the simulated specific soil characteristics at the point locations were then used to produce full coverage maps at the particular time intervals by regression kriging such maps are believed to provide useful information for geoarcheological studies and archeological land evaluations

are oxygen and carbon isotopes of mollusc shells reliable palaeosalinity indicators in marginal marine environments a case study from the middle jurassic of england stable isotope analyses of non luminescent texturally pristine oyster calcites praexogyra hebridica are presented from bathonian inner ramp limestones in central eastern england a relatively large range of values 18 o 2 0 to 2 3 pdb 13 c 0 9 to 3 7 pdb define a crude positive covariance which can be regionally correlated with an offshore tonearshore increase in faunal restriction this palaeoenvironmental stress gradient has previously been interpreted as a consequence of fluctuating nearshore palaeo salinities due to episodic or seasonal runoff from surrounding hinterlands covariant 18 o 13 c trends from euryhaline bivalves are commonly ascribed to regional salinity gradients the most isotopically depleted examples representing the greatest influence of fresh water however bathonian palaeogeography indictates that the most isotopically depleted oysters inhabited relatively offshore settings assuming an average growth temperature of 25 c these shells were secreted in near normal sea water 18 o 0 4 smow in contrast isotopically heavy oyster calcites were produced in highly evaporated nearshore lagoonal waters 18 o up to 4 8 smow modelling the oxygen isotope and chemical evolution of residual waters during evaporation suggests that up to 65 of the nearshore water mass was lost probably in a complex of hydrodynamically choked lagoons evaporites were not precipitated in the sediment and geochemical modelling suggests that the lagoon waters may have been brackish rather than marine in origin the regional 13 c trend is contrary to that predicted on the basis of palaeosalinity and may have resulted from variations in organic carbon production decay and fixation in early diagenesis

modelling soil genesis in calcareous loess abstract the soilgen1 model was developed to simulate soil development in calcareous loess at holocene 15 000 bp present temporal extent we used the leachc model as a core and added process formulations to describe the effect of vegetation and soil macrofauna on various soil properties a limited calibration was done on the calcite solubility constant by comparing decarbonization rates in various leaching climates with values predicted by the metamodel of egli and fitze egli m and fitze p 2001 quantitative aspects of carbonate leaching of soils with differing ages and climates catena 46 35 62 soil profiles of c and ph after 15 000 years compared well with measurements in a belgian loess profile that was never under agriculture taking the composition of the c horizon as uniform parent material scenarios with and without agriculture with varying degrees of bioturbation and for documented holocene climatic and vegetation evolutions in belgium and hungary were simulated and compared results show a clear effect of bioturbation on soil development especially in the continental climate evolution of hungary indicators for the possible occurrence of clay migration and disturbance of lateglacial morphology were calculated and these also show the importance of bioturbation

growth pattern and oxygen isotopic systematics of modern freshwater mollusks along an elevation transect implications for paleoclimate reconstruction abstract fossil mollusk shells are widely distributed in the geologic records and their oxygen isotopic compositions have been used to reconstruct seasonality local climatic and elevation conditions however interpretation of isotope data from fossil shells to estimate paleoclimate and elevation is often ambiguous this study examines the oxygen isotopic systematics of modern freshwater gastropods bellamya and radix shells along an elevation climate transect in the asian monsoon region of china to improve the accuracy of paleoclimate and paleoelevation reconstruction using stable isotopes in fossil shells the results from sclerochronological analyses of the shells show that the intra shell oxygen isotopic pattern is determined by seasonal variations in lake water temperature and water isotopic composition as well as the life cycle of the organism both bellamya and radix appear to grow throughout the year in lakes where water temperature does not fall below 13 c radix in the high elevation cold habitat although prefers to grow in the warmer months can survive through the freezing temperature the 18o patterns in the shells are similar across the elevation climate transect showing high 18o values in the winter months and low 18o values in the summer months consistent with the expected pattern in asian monsoon region the average growth rates of the shells were highest at the lowest elevation site warm and humid climate but were similar at the mid to high elevation sites for large shells 2 2 cm for bellamya and 1 4 cm for radix average growth temperatures calculated using the aragonite oxygen isotope thermometer closely approximate the annual mean water temperature while their intra shell variability is a good proxy for the amplitude of seasonal variations in monthly air temperature this suggests that large shells of both bellamya and radix are excellent archives of lake environmental conditions and most suitable for paleoenvironmental studies

insight into factors controlling formation rates of pedogenic carbonates a combined geochemical and isotopic approach in dryland soils of the us southwest abstract natural accumulation of pedogenic carbonates has been well documented but few studies have focused on carbonate formation in agricultural drylands this study aims to determine accumulation rates of pedogenic carbonates in intensively irrigated soils and to define key linkages between flood irrigation salt loading and soil atmosphere co 2 exchange in cultivated drylands of the southwestern united states we used a combination of elemental chemistry cao soil organic and inorganic carbon contents mineralogy and u series 238 u 234 u 230 th disequilibrium dating technique to investigate calcium sources ages and formation rates of pedogenic carbonates study sites include an irrigated alfalfa field near el paso in western texas and a non irrigated natural dryland site on the usda jornada experimental range of southern new mexico our results showed that large amounts of dissolved calcium and inorganic carbon along with other soluble elements were loaded onto agricultural fields through irrigation waters in el paso tx while dust and rainfall were important for salt loading in natural soils of the jornada u series activity ratios 234 u 238 u and 230 th 238 u in bulk soils suggested eolian deposits added u and modified u isotopes in shallow soils at both the irrigated and natural sites mobility of 234 u within the soil profile is related to leaching of u and by inference other soluble ions and carbonate accumulation at depth the u series dating technique in pedogenic carbonates revealed the presence of much younger carbonates at the irrigated site compared to the natural site pedogenic carbonate formation rates in the irrigated soils were also much higher than those in the non irrigated soils likely a result of influxes from dissolved ca and inorganic carbon in water used for irrigation this study demonstrates the potential for agricultural expansion and land use change in drylands to increase rate of pedogenic carbonate accumulation such changes may have important implications to global carbon cycling since drylands are forecast to become the most expansive terrestrial biome by mid century and dryland agriculture is expanding quickly

what do we really know about early diagenesis of non marine carbonates abstract non marine carbonate rocks including cave spring stream calcrete and lacustrine palustrine sediments are susceptible to early diagenetic processes these can profoundly alter the carbonate fabric and affect paleoclimatic proxies this review integrates recent insights into diagenesis of non marine carbonates and in particular the variety of early diagenetic processes and presents a conceptual framework to address them with ability to study at smaller and smaller scales down to nanometers one can now observe diagenesis taking place the moment initial precipitates have formed and continuing thereafter diagenesis may affect whole rocks but it typically starts in nano and micro environments the potential for diagenetic alteration depends on the reactivity of the initial precipitate commonly being metastable phases like vaterite ca oxalates hydrous mg carbonates and aragonite with regard to the ambient fluid furthermore organic compounds commonly play a crucial role in hosting these early transformations processes like neomorphism inversion and recrystallization cementation and replacement generally result in an overall coarsening of the fabric and homogenization of the wide range of complex primary microtextures if early diagenetic modifications are completed in a short time span compared to the annual to millennial time scale of interest then recorded paleoenvironmental signals and trends could still acceptably reflect original depositional conditions however even compact non marine carbonate deposits may behave locally and temporarily as open systems to crystal fluid exchange and overprinting of one or more geochemical proxies is not unexpected looking to the future relatively few studies have examined the behaviour of promising geochemical records such as clumped isotope thermometry and non conventional stable isotopes in well constrained diagenetic settings ongoing and future in vitro and in situ experimental approaches will help to investigate and detangle sequences of intermediate diagenetic products processes and controls and to quantify rates of early diagenesis bridging a gap between nanoscale molecular lab studies and the fossil field rock record of non marine carbonates