classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

summer air temperature reconstructions from the last glacial stage based on rodents from the site taillis des coteaux vienne western france the oxygen isotope composition of phosphate from tooth enamel of rodents 18op constitutes a valuable proxy to reconstruct past air temperatures in continental environments this method has been applied to rodent dental remains from three genera arvicola sp microtus sp and dicrostonyx sp coming from taillis des coteaux vienne france this archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole upper palaeolithic including seven stratigraphic layers dated from 35 to 17 cal ka bp the abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation of the site differences between 18op values of arvicola sp and microtus sp teeth are interpreted as the result of heterochrony in tooth formation as well as differences in ecology mean 18op values of microtus sp are preferentially used to reconstruct summer air temperatures which range from 16 0 3 7 to 19 1 3 1 c throughout the sedimentary sequence however the highest variability is observed during the last glacial maximum

the modern record of concretionary carbonate reassessing a discrepancy between modern sediments and the geologic record abstract carbonate concretions have long been recognized as common constituents of sedimentary rocks exposed in outcrop although formation mechanisms vary organic matter degradation often plays a role in carbonate concretion authigenesis providing a source of alkalinity for mineral production perhaps surprisingly modern examples of concretionary carbonates are rarely identified in cores despite ubiquitous organic matter degradation in marine sediments this has prompted the general notion that the modern record of concretionary carbonate does not mirror that preserved in the geologic record here we present data from continental margin sediments that receive enhanced delivery of organic matter and demonstrate that concretionary carbonates are indeed recovered from many of these sites in addition sites where concretionary carbonates have not been recovered exhibit chemical profiles that suggest local authigenesis the lack of concretion recovery from some locations likely reflects the poor potential for modern coring techniques to adequately capture concretions or provide context for their identification once recovered concretionary carbonate recovered from the peru margin cascadia the gulf of california the cariaco basin and the western margin of southern africa exhibit evidence for modern or very recent formation via methanogenesis or the anaerobic oxidation of methane demonstrably modern organotrophic sulfate reduction concretions have not been found

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

what does the oxygen isotope composition of rodent teeth record oxygen isotope compositions of tooth phosphate 18op were measured in 107 samples defined on the basis of teeth obtained from 375 specimens of extant rodents these rodents were sampled from pellets collected in europe from 38 n portugal to 65 n finland with most samples coming from sites located in france and spain large oxygen isotopic variability in 18op is observed both at the intra and inter species scale within pellets from a given location this isotopic variability is partly explained by heterochrony in tooth formation related to the short time of mineralization for all rodent species as well as the duration of mineralization that is species dependent consequently tooth phosphate of rodents records a short seasonal interval in the oxygen isotope compositions of meteoric waters 18omw in addition inter species isotopic variability observed in the same pellets suggests behavioural differences implying distinct isotopic compositions for species living in the same location at the scale of europe a robust linear oxygen isotope fractionation equation was determined for muroidea between the midrange 18op values and 18omw values 18op 1 21 0 20 18omw 24 76 2 70 with r2 0 79 n 9 p 0 0001

coal facies studies in spain this work is a synthesis of the distribution of the main coal basins and sub basins in spain as well as the research carried out on their coal facies the coal fields are distributed through the paleozoic mainly pennsylvanian mesozoic cretaceous and cenozoic times peats also exist in the southeast spain granada area although these types of deposits are not included in this review spanish coal basins are both of a paralic and intramontane type and the coal rank is highly variable from lignite in the case of the younger coal seams to anthracite for those of carboniferous age

magnetic properties of sedimentary greigite fe3s4 an update greigite fe3s4 is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction it can also grow at any time when dissolved iron and sulfide are available during diagenesis greigite is important in paleomagnetic environmental biological biogeochemical tectonic and industrial processes much recent progress has been made in understanding its magnetic properties greigite is an inverse spinel and a collinear ferrimagnet with antiferromagnetic coupling between iron in octahedral and tetrahedral sites the crystallographic c axis is the easy axis of magnetization with magnetic properties dominated by magnetocrystalline anisotropy robust empirical estimates of the saturation magnetization anisotropy constant and exchange constant for greigite have been obtained recently for the first time and the first robust estimate of the low field magnetic susceptibility is reported here the curie temperature of greigite remains unknown but must exceed 350 c greigite lacks a low temperature magnetic transition on the basis of preliminary micromagnetic modeling the size range for stable single domain behavior is 17 200 nm for cubic crystals and 17 500 nm for octahedral crystals gradual variation in magnetic properties is observed through the pseudo single domain size range we systematically document the known magnetic properties of greigite at high ambient and low temperatures and with alternating and direct fields and illustrate how grain size variations affect magnetic properties recognition of this range of magnetic properties will aid identification and constrain interpretation of magnetic signals carried by greigite which is increasingly proving to be environmentally important and responsible for complex paleomagnetic records including widespread remagnetizations

stable isotopes reveal differential patterns of holocene environmental change among tuco tucos rodentia ctenomyidae ctenomys from patagonia abstract to explore the role of past environmental changes in shaping interspecific differences in genetic structure among tuco tucos rodentia ctenomyidae ctenomys from the limay valley of northern patagonia we compared 13c and 18o values for modern and historical tooth enamel from the colonial tuco tuco c sociabilis and the parapatric patagonian tuco tuco c haigi specifically we sought to test the hypothesis that a mid holocene loss of genetic variation in c sociabilis was associated with environmental change for both species the 13c composition of tooth enamel differed significantly 5 1 difference in mean 13c values between modern and holocene 0 5 12 kyr b p samples suggesting marked temporal changes in the vegetation consumed for c sociabilis no statistically significant differences in the 13c composition of teeth were found among individuals from the early middle and late holocene in contrast significant differences in 13c values were found between middle and late holocene samples from c haigi none of our analyses revealed statistically significant differences in 18o values thus although the diets of both study species have changed from the holocene to the present only c haigi experienced significant dietary changes during the holocene we suggest that the ecologically more specialized c sociabilis continued to consume the same food resources even as changing holocene conditions caused preferred habitats to disappear in contrast the more generalized c haigi altered its diet allowing populations of this species to remain widespread despite changing holocene environments

oxygen isotope compositions of phosphate from arvicoline teeth and quaternary climatic changes gigny french jura oxygen isotope compositions of biogenic phosphates from mammals are widely used as proxies of the isotopic compositions of meteoric waters that are roughly linearly related to the air temperature at high and mid latitudes an oxygen isotope fractionation equation was determined by using present day european arvicoline rodents tooth phosphate d 18 op 20 98 f0 59 0 572 f0 065 d 18 ow this fractionation equation was applied to the late pleistocene karstic sequence of gigny french jura comparison between the oxygen isotope compositions of arvicoline tooth phosphate and greenland ice core records suggests to reconsider the previously established hypothetical chronology of the sequence according to the d 18 o value of meteoric water mean air temperature relationships the d 18 o value of arvicoline teeth records variations in mean air temperatures that range from 0j to 15jc

influences on the stable oxygen and carbon isotopes in gerbillid rodent teeth in semi arid and arid environments implications for past climate and environmental reconstruction abstract the stable isotope composition of small mammal tissues has the potential to provide detailed information about terrestrial palaeoclimate and environments because their remains are abundant in palaeontological and archaeological sites and they have restricted home ranges applications to the quaternary record however have been sparse and limited by an acute lack of understanding of small mammal isotope ecology particularly in arid and semi arid environments here we document the oxygen and carbon isotope composition of gerbillinae gerbil tooth apatite across a rainfall gradient in northwestern africa in order to test the relative influences of the 18o 16o in precipitation or moisture availability on gerbil teeth values the sensitivity of tooth apatite 13c 12c to plant responses to moisture availability and the influence of developmental period on the isotopic composition of gerbil molars and incisors the results show that the isotopic composition of molars and incisors from the same individuals differs consistent with the different temporal periods reflected by the teeth molar teeth are permanently rooted and form around the time of birth whereas incisors grow continuously the results indicate that tooth choice is an important consideration for applications as proxy quaternary records but also highlights a new potential means to distinguish seasonal contexts the oxygen isotope composition of gerbil tooth apatite is strongly correlated with mean annual precipitation map below 600 mm but above 600 mm the teeth reflect the oxygen isotope composition of local meteoric water instead predictably the carbon isotope composition of the gerbil teeth reflected c3 and c4 dietary inputs however arid and mesic sites could not be distinguished because of the high variability displayed in the carbon isotope composition of the teeth due to the microhabitat and short temporal period reflected by the gerbil we show that the oxygen isotope composition of small mammal teeth strongly reflects moisture availability in semi arid and arid environments and would provide an excellent record of palaeo aridity in a terrestrial setting the results illustrate that an understanding of an animal s physiology is essential for interpreting the animal s isotopic responses to external contexts especially in arid zones

microbial sand chips a non actualistic sedimentary structure abstract microbial mats show a marked decline with the transition from the precambrian to the phanerozoic most likely due to the advent of effective benthic grazing organisms hitherto most aquatic sediments up to sand grade were commonly coagulated by organic material allowing reworking to form intraclasts new term microbial sand chips presence of a microbial mat is indicated 1 by refractory remains of organic matter in the laminated parent sediment 2 by the concentration of early diagenetic pyrite associated with sandy intraclasts in quartzites indicating a concentration of organic matter in the clast and 3 by plastic deformation of the clasts during the erosive event as bioturbation spread into most aquatic depositional environments during the phanerozoic the formation of microbial sand chips became restricted to habitats where bioturbation and grazing are limited by environmental stress and where the preservation potential for microbial sand chips is very low therefore the widespread formation of microbial sand chips in precambrian sandy subaqueous sediments is non actualistic

new interpretations of the facies of the rhenish brown coal of west germany abstract new ideas concerning the understanding of the facies of the rhenish brown coal of west germany are discussed these new interpretations are based on a significantly larger number of samples and refined procedures for analysis within the field of paleobotany palynology coal petrology and organic geochemistry than were available to p w thomson and m teichmuller the light and dark bands in the coal are mainly the result of different degrees of plant decomposition the influence of the peat forming plant communities plays a subordinate role in the petrographical composition of these particular strata of the rhenish brown coal

sem analysis of siderite cements in intertidal marsh sediments norfolk england abstract siderite concretions and more continuous cemented layers are fairly common in intertidal marsh sediments on the coast of east anglia concretions from the norfolk coast at warham have been examined by scanning electron microscopy in the secondary electron and backscattered electron modes and by microprobe analysis siderite occurs primarily as passive void filling cement and as coatings on quartz grains no evidence of quartz replacement or displacement was found in the sections examined the siderite is somewhat variable in composition but is predominantly relatively pure with less than 6 ionic magnesium substitution x ray powder diffraction and sem analyses have shown that small amounts of calcite greigite and iron monosulphides are also present siderite is currently forming at very shallow depths in rapidly accreting marsh sediments which have large amounts of decaying organic matter high bacterial activity and low interstitial concentrations of dissolved sulphate and h 2 s

correlation between the oxygen isotope ratio of north american bison teeth and local waters implication for paleoclimatic reconstructions abstract the oxygen isotope ratios of tooth enamel carbonate from 64 north american bison bison bison from eleven locations were measured the mean enamel oxygen isotope ratios for bison populations ranged from 28 3 to 15 9 smow and correlated well with the annual mean oxygen isotope ratios of local surface waters and precipitation the standard deviation of oxygen isotope values among different individuals within each bison population averaged 1 0 and ranged from 0 7 to 1 4 the variability of enamel oxygen isotope ratios was not significantly different among different populations and did not correlate with changes in temperature precipitation or relative humidity these results demonstrate that the average oxygen isotope values of bison tooth enamel can be used for use as a quantitative proxy for reconstructing the values of surface waters and therefore may provide valuable paleoclimatic information this study provides a baseline comparison for analyses of the oxygen isotope ratios of bison and other large herbivores from across north america

a case for in vivo mass independent fractionation of mercury isotopes in fish the recent discovery of mass independent fractionation of mercury isotopes allows new constraints to be placed on the mercury cycle here we report new hg isotopic analyses of zooplankton and fish from different trophic levels of a freshwater lake lake jackson florida bearing systematic mass independent fractionation of mercury isotopes fish muscle tissues show a progressive enrichment in the odd mass mercury isotopes having odd atomic mass numbers 199 and 201 with increasing trophic level trophic level was determined based on nitrogen isotopic composition as well as fish stomach content zooplankton in the lake contain mercury with 199hg and 201hg values of 0 43 0 07 and 0 44 0 07 respectively the 199hg values increase by 1 from 0 4 in zooplankton juvenile bluegill and several other small fishes to 199hg 1 36 for the florida gar which is the top predator fish in the lake previous observations of odd mass number isotope enrichment of mercury have been explained by photoreduction and demethylation of methyl mercury in the water column or as isotope effects related to microbial methylation however our data and the data of jackson et al 2008 are also consistent with in vivo production of mass independent fractionation considering the alternatives mass independent fractionation by metabolic processes is the most straightforward explanation for the mercury isotope data there are two known mechanisms for mass independent fractionation of mercury i e the nuclear volume effect and the magnetic isotope effect while the data are insufficient to serve as proof the magnitude of the mass independent effect and the nearly equal enrichment of 199hg and 201hg seem most suggestive of a magnetic isotope effect

carbon isoscapes of rodent diets in the great plains usa deviate from regional gradients in c4 grass abundance due to a preference for c3 plant resources abstract diet is an ecological attribute that species may adjust to cope with changing environments and may indicate how a population responds to changes in resource availability in the great plains plants utilizing the c4 photosynthetic pathway may increase in abundance in the future because of their high tolerance for warm and dry environments which are projected to increase how increased c4 abundance will influence grassland food webs remains unknown here we evaluate how rodent diets vary relative to c4 plant biomass at the regional scale of the southern great plains in the u s we measured 13c values of hair from 534 individuals of 14 rodent species resulting isoscapes of 13c values were statistically compared to three proxies for local abundance of c4 grasses across the region overall diets of most rodent species were dominated by c3 derived resources with a few species relying on c4 resources ordinary least squares linear regressions indicate that proxies for regional abundance of c4 grasses explain very little of the variance in 13c values in hair for the entire rodent community however the isoscape of rodent hair 13c values does broadly correspond to that for 13c values of soil organic matter the difference between median 13c values of granivores and folivores is significantly and highly correlated with som 13c values results from this study can be used as a baseline for characterizing dietary shifts in response to environmental change both in the geological past and in the future and they identify which dietary categories may be most sensitive to future changes in the regional abundance of c4 grasses

long term accretion rates on tidal salt marshes abstract long term variations in salt marsh accretion rates were estimated using data collected on the marshes of the north norfolk coast england fourteen discrete marsh areas were sampled all lying within a 20 km stretch of coast the age of each marsh had previously been determined using radiocarbon or archival evidence for the date of vegetation inception on each marsh surface marsh ages ranged from 10 years to 2000 years the elevation of each marsh surface was determined in the field using levelling techniques the relationship between age and surface elevation was assumed to be a function of the rate of marsh accretion within this area of coast statistical tests showed this to be a highly significant relationship while the accretion rates calculated from the age height curve agree closely with field measurements on these marshes accretion rates were found to vary from 1 7 cm yr on 10 year old marshes to less than 0 002 cm on marshes older than 500 years the age height relationship describes an asymptotic curve with the asymptote lying 0 8 m below the level of the highest spring tides and appears to be controlled by the frequency of tidal maxima which peaks at 0 8 m below the maximum value and declines sharply above that height

coal measures namurian and westphalian blackband iron formations fossil bog iron ores blackband iron formations are essentially thin approximately 0 75 m thick siderite rich total iron up to 40 carbonaceous laminated mudrocks which commonly occur in grey coal bearing sequences in close proximity to coal seams they exhibit a conspicuous laminated macrotexture made up of carbonaceous and siderite rich laminae together with primary textures such as root disturbed laminae sideritized unflattened spores and preservation of plant cell detail these all point to formation of siderite soon after deposition in some cases before significant compaction their enclosing sediments clearly show that they were deposited in environments intermediate between delta top alluvial floodplains and coastal plain swamps in which small areas were subjected to periods of lacustrine deposition the presence of varved mudrocks and oil shales in the beds directly above many of the blackband iron formations and the distinctive fine lamination of the blackbands are evidence of such depositional environments the blackband iron formations are considered to have been formed in a similar way to recent bog iron ores and are therefore interpreted as fossil bog iron ores a model for their mode of formation is presented

forecasting coal resources and reserves in heterogeneous coal zones using 3d facies models as pontes basin nw spain abstract forecasting coal resources and reserves is critical for coal mine development thickness maps are commonly used for assessing coal resources and reserves however they are limited for capturing coal splitting effects in thick and heterogeneous coal zones as an alternative three dimensional geostatistical methods are used to populate facies distribution within a densely drilled heterogeneous coal zone in the as pontes basin nw spain coal distribution in this zone is mainly characterized by coal dominated areas in the central parts of the basin interfingering with terrigenous dominated alluvial fan zones at the margins the three dimensional models obtained are applied to forecast coal resources and reserves predictions using subsets of the entire dataset are also generated to understand the performance of methods under limited data constraints three dimensional facies interpolation methods tend to overestimate coal resources and reserves due to interpolation smoothing facies simulation methods yield similar resource predictions than conventional thickness map approximations reserves predicted by facies simulation methods are mainly influenced by a the specific coal proportion threshold used to determine if a block can be recovered or not and b the capability of the modelling strategy to reproduce areal trends in coal proportions and splitting between coal dominated and terrigenous dominated areas of the basin reserves predictions differ between the simulation methods even with dense conditioning datasets simulation methods can be ranked according to the correlation of their outputs with predictions from the directly interpolated coal proportion maps a with low density datasets sequential indicator simulation with trends yields the best correlation b with high density datasets sequential indicator simulation with post processing yields the best correlation because the areal trends are provided implicitly by the dense conditioning data

optimum and robust 3d facies interpolation strategies in a heterogeneous coal zone tertiary as pontes basin nw spain coal exploration and mining in extensively drilled and sampled coal zones can benefit from 3d statistical facies interpolation starting from closely spaced core descriptions and using interpolation methods a 3d optimum and robust facies distribution model was obtained for a thick heterogeneous coal zone deposited in the non marine as pontes basin oligocene early miocene nw spain several grid layering styles interpolation methods truncated inverse squared distance weighting truncated kriging truncated kriging with an areal trend indicator inverse squared distance weighting indicator kriging and indicator kriging with an areal trend and searching conditions were compared facies interpolation strategies were evaluated using visual comparison and cross validation moreover robustness of the resultant facies distribution with respect to variations in interpolation method input parameters was verified by taking into account several scenarios of uncertainty the resultant 3d facies reconstruction improves the understanding of the distribution and geometry of the coal facies furthermore since some coal quality properties e g calorific value or sulphur percentage display a good statistical correspondence with facies predicting the distribution of these properties using the reconstructed facies distribution as a template proved to be a powerful approach yielding more accurate and realistic reconstructions of these properties in the coal zone

unravelling the oxygen isotope signal δ18o of rodent teeth from northeastern iberia and implications for past climate reconstructions abstract small mammals especially rodents constitute valuable proxies for continental quaternary environments at a regional and local scale recent studies have demonstrated the relation between the stable oxygen isotope composition of the biogenic phosphate from rodent teeth 18op and the oxygen isotope composition of meteoric waters 18omw which is related to air temperatures at mid and high latitudes this work explores the 18op of rodent tooth enamel from murinae and arvicolinae subfamilies to investigate the palaeoenvironmental conditions in northeastern iberia during marine isotope stage 3 mis 3 ca 60 30 ka fourteen new 18op analyses from modern samples in conjunction with forty six 18op analyses previously published are used to decipher the isotope record of present day rodent teeth in this region two main factors should be considered in iberian palaeoenvironmental reconstructions the singular nature of iberian 18omw records and the potential seasonality bias of small mammal accumulation methodological proposals are made with a view to ensuring the correct interpretation of the 18op of small mammals in reconstructing past air temperatures this methodology is applied to the mis 3 sequence of the cova dels xaragalls site vimbodi poblet tarragona spain where fifty one 18o analyses were performed on wood mouse apodemus sylvaticus lower incisors a spring early summer accumulation of small mammals is suggested for the layers at cova dels xaragalls in agreement with previous environmental studies of the site variations in the 18op values suggest slight fluctuations in the climatic conditions throughout the sequence which are consistent with the stadial interstadial alternations that characterized mis 3 complementary palaeoenvironmental methods determine cooler conditions than nowadays but within a globally stable climatic period

dolomitisation of the ardross limestones dinantian east fife scotland abstract the ardross limestones are two thin marine units within the otherwise dominantly delta top sediments of the upper calciferous sandstone measures of east fife they are entirely dolomitised bioclastic wackestones which are cut by complex dolomite ankerite veins the matrix of these limestones is composed of brown microcrystalline dolomite together with a significant amount of framboidal pyrite and small amounts of siderite the matrix dolomite usually has compositions of between 50 and 51 mol caco3 8 15 mol feco3 and up to 1 5 mol mnco3 matrix 18o 8 31 to 1 58 the veins comprise mn enriched 18o depleted inclusion rich dolomite succeeded by 18o enriched ankerite dolomitisation appears to have been a two stage process in which an early fine grained protodolomite phase recrystallised in hydrothermal fluids associated with namurian volcanic emplacement the protodolomite was precipitated during earliest burial from marine dominated fluids largely within the zone of sulphate reduction the later recrystallisation of this material was accompanied by precipitation of the earliest vein dolomites later ankerite veins were precipitated from deep diagenetic brines released during some phase of post carboniferous regional extension geochemical and petrographic differences between dolomite in the ardross limestones and that in similar crinoidal wackstones of the overlying lower limestone group in east fife can be attributed to primary sedimentary differences and contrasting early burial histories

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

oxygen isotope variations in phosphate of biogenic apatites iv mammal teeth and bones groups of rats grown from birth to death in identical conditions but with different 18o of drinking water w were studied for variations of 18o of their body water bw and bone phosphate p there is a high linear correlation r 0 99 between bw and between p and w the regression lines have similar slope coefficients 0 53 and 0 49 values of p of different teeth and bones are the same within the precision of the method 0 5 the isotopic fractionation coefficient between phosphate and body water is 1 0178 and close to the estimated value of 1 0173 derived from the phosphate paleotemperature equation deviations from constant fractionation between bone phosphate and environmental drinking water depend primarily on rates of drinking and metabolism environment conditions have relatively little effect on oxygen isotope fractionation between water sources and bone phosphate

palaeochannels in mine workings in the high hazles coal westphalian b nottinghamshire coalfield england palaeochannels have numerous deleterious effects on coal mining including the formation of washouts and their detection and delineation in the subsurface is of paramount importance a palaeochannel system in the roof of the high hazles coal westphalian b at gedling colliery nottinghamshire is described the roof strata of this seam are interpreted as the deposits of a lacustrine delta complex formed on an upper delta plain with the palaeochannels constituting minor deltaic distributaries the lacustrine delta front deposits consist of a coarsening upwards sequence of siltstones and sandstones which form a sheet like body of coalescing distributary mouth bars that were laid down by friction dominated effluents the distributary channels were filled by a variety of processes giving rise to complex channel deposits bedload deposition of sand on bars collapse and sloughing of channel banks and deposition of silts and muds from suspension were important mechanisms the nature of the deposits reflects the mode of channel abandonment rather than equilibrium channel processes overbank flood deposits and prodelta lacustrine mudstones are also described from the high hazles roof based on this study criteria are suggested that may enable the successful detection and delineation of palaeochannels in mine workings elsewhere

is small beautiful a review of the advantages and limitations of using small mammal teeth and the direct laser fluorination analysis technique in the isotope reconstruction of past continental climate change abstract oxygen isotopes in mammalian tooth enamel have become a widely used proxy for reconstructing past continental climate change however owing to sample size constraints in the chemical separation and precipitation of the phosphate prior to oxygen isotope analysis this technique has been until recently limited to relatively large mammal teeth as the result of recent developments in chemical and analytical techniques including the development of a novel pre treatment technique and a direct laser fluorination methodology of analysis small mammal teeth rodents which are relatively more abundant in the fossil record than large mammal teeth can now be used published examples from the recent literature are provided with the aim of examining the advantages and limitations of using small mammal teeth in palaeoclimate reconstruction studies issues that are addressed include 1 the rationale behind the calculation of the mean oxygen isotope composition of local water and the problems associated with the intake of 18 o enriched water from plant food and from small water bodies fractionated as a result of evaporation 2 the methodology justification and limitations in determining mean annual temperatures mats from calculated 18 o local water values and also combining the 18 o local water values with 18 o values from freshwater biota to calculate using established thermometry equations multiple palaeotemperatures of differing climatic significance 3 specific published examples of how the phosphate oxygen isotope composition of small mammal teeth are being used in studies of continental climate change

variability in the oxygen isotope compositions of modern rodent tooth carbonate implications for palaeoclimate reconstructions abstract the stable oxygen isotope values 18o of small mammal teeth can potentially provide important palaeoclimate records for quaternary sequences due to the abundance of these remains in various depositional environments however the application of this proxy to quaternary climate reconstructions has hitherto been limited due to 1 uncertainties in the relationship between the 18o of small mammal teeth and the 18o of meteoric water and 2 a lack of understanding regarding the importance of isotopic variability in influencing this relationship the oxygen isotope values of 145 modern short tailed field vole teeth rodentia microtus agrestis l collected from four uk sites were analysed to address these uncertainties the results demonstrate that in general there are no significant 18o offsets between molars and incisors from the same rodent population conversely isotope variability between different individuals within a population is significant thus when investigating the 18o compositions of rodent teeth in modern and past environments analyses must ideally be undertaken on 7 10 molars or incisors from the same site or sedimentary unit this is in order to obtain reliable mean 18o values at 90 statistical confidence it is also demonstrated that statistically significant differences in the mean 18o values of rodent teeth occur between lowland sites in the uk the spatial trend in the mean 18o of rodent tooth carbonate is shown to follow a linear relationship with the mean 18o of local meteoric water this relationship approximately parallels published calibrations for the 18o of rodent tooth phosphate in europe the results additionally indicate that complex hydrological conditions in northern and highland areas can lead to a mismatch between the measured 18o values of meteoric water and rodent teeth a detailed understanding of the environmental controls on the 18o values of water sources and rodents in these regions is therefore needed

pliocene lignites from apofysis mine amynteo basin northwestern greece petrographical characteristics and depositional environment coal petrological investigation along with proximate and elemental analyses were undertaken to determine the petrographic characteristics of the apofysis lignites amynteo basin northwestern greece and their depositional environment eight samples representing different lignite beds of the apofysis deposit were collected from a borehole the apofysis lignites have an eu ulminite b reflectance of rr 0 22 and in terms of lithotype belong to matrix soft brown coals huminite is the most abundant maceral group and consists mostly of humodetrinite inertinite has relatively low percentages whereas liptinite concentrations are low in the lower lignite beds and higher in the upper ones ternary plots and facies indices were employed in order to investigate the palaeoenvironment the depositional environment of the apofysis lignites is not definitely ascribed to a forest swamp or a reed marsh environment the high ash content of the analysed samples is a clear indication of a topogenous setting low tissue preservation index tpi and high gelification index gi values are observed high alkalinity and strongly reducing conditions may be inferred from the presence of syngenetic framboidal pyrite the low tpi values which indicate high bacterial activity and thus high ph conditions and the preservation of gastropod shells and chlorophyllinite high gi indicates a constant influx of calcium rich waters into the coal swamp the apofysis lignite deposit may be interpreted to be autochthonous to hypoautochthonous the peat accumulation was governed by a high groundwater level wet telmatic to limno telmatic facies and a moderate subsidence rate

marshrock formed by iron sulphide and siderite cementation in saltmarsh sediments the formation of authigenic sulphides and other iron minerals has proved interesting both in studies of palaeomagnetism1 and palaeosalinity reconstructions of pleistocene and older sediments2 3 iron sulphide and siderite cemented nodules concretions and layers are fairly common in the geological record4 6 but there is little evidence of their formation in modern environments accounts of authigenic iron minerals forming today in marine and brackish sediments generally refer only to micro concretions 10 500 m in size many of which have a framboidal texture3 7 8 i describe here macro concretions and cemented layers which are now forming within intertidal marsh sediments at warham norfolk uk parts of these marshes are only 30 yr old indicating how quickly early diagenetic cementation can occur siderite feco3 greigite fe3s4 and possibly mackinawite fes1 x are the main cementing agents the term marshrock is proposed for the cemented sediments by analogy with calcareous beachrock9 10 the formation of siderite monosulphide concretions in the warham sediments probably reflects a high reactive iron content and limited sulphate arising from rapid sedimentation and burial of organic matter during the early stages of marsh growth

pleistocene and holocene palaeoclimates in the gebel akhdar libya estimated using herbivore tooth enamel oxygen isotope compositions abstract the palaeoclimate of the gebel akhdar massif in cyrenaica northeast libya is investigated using the stable oxygen isotope ratio 18 o of herbivore tooth enamel from the archaeological faunal assemblages of the haua fteah and hagfet ed dabba caves samples accumulated through human activity at the sites thus climatic interpretations are in direct chronological association with periods of human presence in the local landscape wild ammotragus lervia barbary sheep and bos sp auroch and domestic ovis sp and capra sp from the levalloiso mousterian 73 3 43 5 ka to the neolithic 9 3 5 4 ka cultural phases are analysed results indicate that the most arid environment represented by the samples occurred at 32 ka when populations associated with dabban lithic assemblages were present within the region climatic instability increased during oxygen isotope stage 2 consistent with other palaeoenvironmental investigations in the gebel akhdar there is no evidence for hyper arid events during the last glacial and surface water most probably in the form of local springs was available throughout the time periods considered overall results indicate that different cultural groups occupied the gebel akhdar landscape under different climatic conditions but that climate variations appear to have been of lower magnitude than those that occurred at inland north african locations these reconstructions provide further support to the theory that the gebel akhdar may have served as a refugium for human populations in north africa during times of global climatic extremes

palaeoenvironment and palaeoclimate of the middle miocene lake in the steinheim basin sw germany a reconstruction from c o and sr isotopes of fossil remains a differentiated reconstruction of palaeolimnologic environmental and climatic conditions is presented for the middle miocene long term freshwater lake 14 3 to 13 5 ma of the steinheim basin on the basis of a combined c o and sr isotope study of sympatric skeletal fossils of aquatic and terrestrial organisms from the lake sediments the oxygen isotope composition for lake water of the steinheim basin 18oh2o 2 0 0 4 vsmow n 6 was reconstructed from measurements of 18opo4 of aquatic turtle bones the drinking water calculated from the enamel of large mammals proboscideans rhinocerotids equids cervids suids has 18oh2o values 18oh2o 5 9 1 7 vsmow n 31 typical for middle miocene meteoric water of the area this 18oh2o value corresponds to a mean annual air temperature mat of 18 8 3 8 c calculated using a modern day 18oh2o mat relation hence large mammals did not use the lake water as principal drinking water in contrast small mammals especially the then abundant pika prolagus oeningensis drank from 18o enriched water sources 18oh2o 2 7 2 3 vsmow n 7 such as the lake water differences in sr and o isotopic compositions between large and small mammal teeth indicate different home ranges and drinking behaviour and support migration of some large mammals between the swabian alb plateau and the nearby molasse basin while small mammals ingested their food and water locally changes in the lake level water chemistry and temperature were inferred using isotopic compositions of ostracod and gastropod shells from a composite lake sediment profile calcitic ostracod valves ilyocypris binocularis 18o 1 7 1 2 vpdb 13c 0 5 0 9 vpdb n 68 and aragonitic gastropod shells gyraulus spp 18o 2 0 1 3 vpdb 13c 1 1 1 3 vpdb n 89 have 18o and 13c values similar to or even higher than those of marine carbonates 13c values of the biogenic carbonates parallel lake level fluctuations while 18o values scatter around 2 2 and reflect the short term variability of meteoric water inflow vs longer term evaporation 87sr 86sr ratios of aragonitic gyraulus spp gastropod shells parallel the lake level fluctuations reflecting variable inputs of groundwater and surface waters using a water 18oh2o value of 2 0 vsmow water temperatures calculated from skeletal tissue 18o values of ostracods are 16 7 5 0 c gastropods 20 6 5 6 c otoliths 21 8 1 4 c and fish teeth 17 0 2 7 c the calculated mat 19 c lake water temperatures 17 to 22 c and the 18o enriched water compositions are indicative of warm temperate climatic conditions possibly with a high humidity during this period vegetation in the area surrounding the basin was largely of the c3 type as indicated by carbon isotopic compositions of tooth enamel from large mammals 13c 11 1 1 1 vpdb n 40

mercury isotope fractionation in fossil hydrothermal systems the hg isotopic compositions of samples throughout the vertical extent of two fossil hydrothermal systems were analyzed by multicollector inductively coupled plasma mass spectrometry results show 5 2 0 2 hg 1 9 8 hg relative to nist 3133 fractionation more than 50 times greater than the 0 1 2 external reproducibility of the analyses the hg isotope compositions from both hydrothermal systems can be grouped by dominant mineralogy and position 2 0 2 hg 1 9 8 hg values at the tops of the systems are 3 5 to 0 4 in cinnabar dominant sinter and 0 2 to 2 1 in metacinnabar dominant sinter and the underlying veins have 2 0 2 hg 1 9 8 hg values of 1 4 to 1 3 these differences probably resulted from the combination of boiling of the hydrothermal fluid oxidation near the surface and kinetic effects associated with mineral precipitation the natural variation in hg isotopic compositions observed in this study is higher than that expected from the trend of decreasing mass dependent fractionation with increasing mass extrapolated from stable isotope systems up to z 26 fe confirming that even the heaviest elements undergo significant stable isotope fractionation in hydrothermal systems

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

tectonic palaeoenvironmental forcing of clay mineral assemblages in nonmarine settings the oligocene miocene as pontes basin spain two small alluvial lacustrine subbasins developed during the early restraining overstep stages of the oligocene miocene as pontes strike slip basin nw spain later the basin evolved into a restraining bend stage and an alluvial swamp dominated depositional framework developed the palaeobiological record demonstrates that the oligocene miocene palaeoclimate in nw spain was subtropical warm and humid to subhumid the metamorphic and igneous basin catchment yielded clay assemblages made up by kaolinite illite and al smectite illite occurred as an original mineral in the source rock area whereas kaolinite and al smectite resulted mainly from weathering of feldspar and clinochlore respectively this detrital primary clay assemblage remained preserved in the colluvial alluvial fan and shallow lacustrine facies whose early diagenesis was influenced by diluted poorly evolved pore waters with neutral to slightly alkaline ph the original clay assemblage was mildly to strongly transformed under early diagenetic conditions in the lacustrine and swampy environments where significant hydrochemical and eh ph changes took place a fibrous magnesium rich clay mineral dominated assemblage palygorskite and sepiolite formed in shallow saline lakes and palustrine zones under the influence of magnesium rich alkaline waters moreover kaoliniteenriched assemblages formed in deep lacustrine swamp and swamp related alluvial zones under the influence of slightly to highly acidic pore waters pore water acidic conditions characterising environments with organic matter accumulation led to early diagenetic transformation of al smectite into kaolinite this process was relatively limited in some environments such as organic matter rich bottoms in meromictic lacustrine zones whereas it was pervasive in peat forming swamp zones the stratigraphic relationships between the diverse clay mineral assemblages in the as pontes basin fill demonstrate the coeval development of rather diverse clay compositions this clearly reflects the influence on clay assemblages of palaeoenvironmental changes forced by the morphological and tectonic evolution of the catchment basin system the interplay between climate and tectonic processes in the source areas did not result in major variations of the clay minerals fed into the basin conversely this tectonic sedimentation interplay influenced the evolution of the drainage and the water balance in the depositional zones causing a complex environmental hydrochemical evolution to occur as a consequence drastic early

the petrology and diagenesis of middle jurassic clastic sediments ravenscar group yorkshire the petrology of non marine clastic sediments from the middle jurassic ravenscar group was investigated to identify and to assess the significance of possible controls on diagenesis diagenetic modifications took place in three broad regimes within the depositional groundwater eogenesis during burial mesogenesis and during uplift and erosion telogenesis eogenesis involved the initial interaction of the original sedimentary assemblage with its depositional pore waters eogenetic processes were influenced strongly by bacterial degradation of organic matter present in the finer grained sediments this bacterial activity caused a lowering of pore water ph and subsequently reduced eh feldspar dissolution and alteration of muscovite to kaolinite occurred quartz overgrowths and vermiform kaolinite precipitated in sands with oxygenated and mildly acidic pore waters whereas chlorite and quartz overgrowths formed in sands with anoxic and neutral pore waters this caused complete reduction of porosity in both finer grained and texturally less mature floodplain facies sandstones channel facies sandstones were cemented only with a thin veneer of quartz overgrowths creating a rigid but still porous quartzose framework bacterial ferric iron reduction throughout the water table subsequently established more ubiquitous conditions raised ph and caused rhombic siderite cementation within the remaining porosity mesogenetic modifications of the mineralogy formed at the surface occurred when pore water composition changed during burial bicarbonate saturated solutions migrated through the surviving porosity precipitating replacive poikilotopic ferroan calcite carbonate dissolution occurred subsequently carbonate dissolution was possibly caused by the same solutions which then precipitated dickite and further authigenic quartz telogenetic modifications took place during uplift and exposure groundwater reactions and subaerial exposure probably caused further carbonate and feldspar dissolution as well as alteration of chlorite to interstratified chlorite vermiculite it is concluded that the diagenesis of these non marine clastic sediments reflects various factors the complex interrelationship of which precludes the identification of any single factor as wholly controlling their diagenesis eogenetic modifications involved the interaction of the sediments and their pore waters as a result of the metastability of the mineral assemblage established at this time these modifications can still be recognized despite the sediments subsequent history

relationship between δ18o values for skeletal apatite from reindeer and foxes and yearly mean δ18o values of environmental water abstract the oxygen isotope composition of bone and tooth phosphate of 50 fox specimens and 30 reindeer specimens from various locations with different climatic and environmental conditions was measured the existing relationship between these values and the mean oxygen isotope composition of local meteoric water has been calculated in the case of foxes specimens belonging to two genera vulpes and alopex and three different species were measured the samples fit a straight line whose equation can be used for paleoclimatological studies either in arctic or in temperate regions for reindeer rangifer a relatively large range of isotopic values was obtained from each location suggesting imperfect equilibrium conditions with environmental water the calculated equation can be used for semi quantitative information on local paleowaters at high latitudes only

greigite from carbonate concretions of the ediacaran doushantuo formation in south china and its environmental implications abstract greigite fe 3 s 4 is a ferrimagnetic iron sulfide that commonly forms as a precursor of pyrite in anoxic environments where the supply of reactive fe outpaces that of sulfide h 2 s and hs because of its metastability and sensitivity to redox changes during burial greigite has been rarely documented in rocks older than the cretaceous here we report well preserved greigite in carbonate concretions of the upper doushantuo formation ca 551 ma in the yangtze gorge area south china greigite in the carbonate concretions coexists with anhedral and framboidal pyrite and is distributed in clay rich carbonates with card house microtextures and dolomitic spherical structures indicative of early diagenetic formation during shallow burial preservation of greigite in carbonate concretions of the upper doushantuo formation implies that these concretions maintained a closed micro system since their formation and that they provide information about the ancient depositional and early diagenetic environments

nursing weaning and tooth development in woolly mammoths from old crow yukon canada implications for pleistocene extinctions abstract this study investigates differences in the 13ccol 15n 13csc 18osc sr ca and ba ca values of juvenile and adult woolly mammoths mammuthus primigenius from old crow yukon canada the data indicate that nursing in woolly mammoths lasted at least three years and was associated with minimal decreases in 13ccol 0 2 large decreases in 13csc 1 5 and large increases in 15n 2 and 18osc 2 values sr ca and ba ca ratios suggest that woolly mammoth juveniles began consuming plant foods between 2 and 3 african elephant years of age much later than the initiation of weaning in modern elephants we hypothesize that delayed weaning was an adaptation to increased predation risk and decreased food quality quantity during the extended hours of darkness that occur in winter at high latitudes prolonged nursing and delayed weaning may have made mammoths particularly vulnerable to climatic stressors or human hunting

the coal bearing cenozoic as pontes basin northwestern spain geological influence on coal characteristics lignite deposits in the cenozoic as pontes strike slip basin northwestern spain were formed as a function of specific paleoclimatic conditions and tectonic evolution of the basin during the early evolutionary stages the presence of active normal faults and thrusts inside the basin resulted in two subbasins with distinct differences in sedimentary records with respect to lignite seam occurrence thickness area1 extent and lithotype development in contrast during the late evolutionary stages the basin was not split and a more homogeneous sedimentary record in terms of coal seam occurrence and lithotype characteristics developed a total of 26 lignite samples distributed along the basin infill were analyzed by organic petrography and geochemistry all are lignite b astm the lignites deposited during lower basin infill sedimentation units 1 and 2 are dark matrix rich mainly huminitic brown coals with minor bright liptinitic rich coal lithotypes the dark huminitic coals in these units show sedimentological and paleontological evidence of lacustrine influence persistent relatively moderate to low tissue preservation index tpi values and high average gelification index gi values are characteristic of these limno telmatic coals lignites in the upper basin infill unit 4 are almost exclusively matrix rich huminitic brown coals persistent widespread low tpi values and variable but low average gi values are also characteristic of these telmatic coals the overall coal petrological data trend tpi gi and widespread development or absence of liptiniteenriched lignite layers recorded from the lower to the upper basin infill units agrees with the stratigraphic and sedimentological data which show a trend of increasingly drier conditions development of bright liptinite enriched lignite layers was widespread during the early basin evolutionary stages and was influenced by punctuated water table oscillations sedimentological petrological and organic geochemical data point to the conclusion that although the paleoenvironments where peat deposition took place did not undergo dramatic changes they were affected by distinguishable

petrographic and geochemical characterization of pale and dark brown coal from yunnan province china abstract fifteen lignite samples from the province of yunnan were analysed by organic petrography and geochemistry twelve of the samples represent the very pale yellow baipao coal the other three were normal coals of a medium brown colour the baipao coal consists mainly of mineral bituminous groundmass whereas the normal coal is characterised by well preserved tissues derived from gymnosperm wood up to 190 mg g c org of extract is extractable from the baipao coal only 63 mg g c org from the normal coal the n alkane fraction of the baipao coal extract consists of high amounts of hopanes and shows the predominance of nor abietane within the diterpenoids present the first group of compounds points to intensive bacterial activity while the second compound indicates not only that gymnosperms are present but also that a relatively oxygen rich environment existed at the time of deposition from the petrographic and organic geochemical characteristics it is concluded that the baipao coal was formed from the same plant source material as the normal coal but underwent stronger decay

mass dependent and mass independent variations in the isotope composition of mercury in a sediment core from lake ontario as related to pollution history and biogeochemical processes abstract historical variations in the isotope composition of mercury hg in lake ontario were examined for the purpose of characterising the isotope signatures of the sources of hg contamination and investigating their fate in the environment the lake has been polluted with hg organochlorine compounds and other contaminants from industrial and urban sources chlor alkali plants being historically the principal sources of hg the pollutants were discharged into the niagara river transported to the lake by fluvial action and deposited in fine grained sediments analysis of a dated sediment core from the lake revealed that the hg concentration increased sharply in the 1890s peaked in the 1930s 1940s and 1960s and then declined levelling off in the late 1900s the values of the 198 hg 202 hg 199 hg 202 hg 200 hg 202 hg and 201 hg 202 hg ratios of the hg that formed the peaks decreased with increasing total hg concentration thus the isotope signature of the anthropogenic hg was formed by mass dependent fractionation mdf which caused preferential depletion in the lighter isotopes suggesting evaporation from hg 0 electrodes in the chlor alkali plants the background hg above and below the peaks also showed inverse correlations with total hg but formed separate regression lines reflecting the fact that its origins and pre depositional history were different the isotope signatures were altered appreciably by both mdf and mass independent fractionation mif attributable to natural processes in the lake mdf caused secondary enrichment in lighter isotopes and mif caused intermittent 201 hg enrichment associated with episodes of fe and mn oxyhydroxide precipitation feooh abundance showed a marked dip coinciding with maximum concentrations of organochlorine compounds in the 1960s but 201 hg enrichment by mif increased significantly with the concentrations of certain chlorobenzene compounds these findings suggest that mif was mediated by bacteria including oxyhydroxide precipitating species and that organochlorines inhibited feooh producing bacteria whereas the chlorobenzenes stimulated bacterial enzyme activity involved in mif

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

lead isotope ratios in spanish coals of different characteristics and origin lead isotope ratios in coals of different rank from several spanish basins were estimated and related with their characteristics the isotope 206pb 207pb ratio values of the coals studied range between 1 13 and 1 21 with the exception of some coal samples from the cretaceous which are more radiogenic coals were classified into groups according to their lead isotope ratios these in turn were related to the isotope ratios of the minerals galena pyrite chalcopyrite and carbonates some of the low rank coals in which lead might be expected to be associated with the organic matter were not found to be related with the isotope ratios of minerals the isotope ratios of the individual densimetric fractions separated from a bituminous coal are different to those of the raw coal the differences between these isotope ratios may not only be due to the diverse origin of lead in different coals but also with the possible presence of several lead species incorporated from various sources in a particular coal the results of this work represent an important contribution to the lead isotope ratio database essential for the accurate interpretation of data regarding pollution sources

multiple mechanisms of remagnetization involving sedimentary greigite fe3s4 sedimentary greigite fe3s4 is being increasingly implicated as the carrier of late diagenetic remagnetizations in fine grained marine and terrestrial sediments we have conducted detailed scanning electron microscope observations on polished sections from such sediments coupled with elemental microanalysis to identify greigite and to characterize the mode of occurrence and the relationships between the observed greigite and other authigenic and detrital mineral phases this detailed observational work in conjunction with recently published work has enabled identification of several mechanisms for remagnetization involving greigite 1 neoformation of greigite on the surfaces of early diagenetic framboidal and nodular pyrite 2 greigite growth within cleavages of detrital sheet silicate grains 3 neoformation of greigite on the surfaces of authigenic clays smectite illite 4 greigite nucleation on the surfaces of siderite 5 greigite growth on the surface of gypsum that resulted from earlier oxidation of nodular pyrite many other mechanisms for greigite neoformation are conceivable the key variables are appropriate redox conditions for generation of sulphide and availability of iron from the dissolution of a wide range of possible reactive detrital and authigenic iron bearing minerals documentation of a wide range of mechanisms for neoformation of greigite provides compelling evidence that sediments containing greigite should be routinely suspected of remagnetization which will complicate or compromise studies of environmental magnetism and geomagnetic field behaviour

revisiting the paleomires of western india an insight into the early paleogene lignite corridor abstract the paleocene eocene lignite sequences of western india occur in the bikaner nagaur barsingsar gurha and kasnau matasukh lignite seams and barmer kapurdi and giral lignite seams basins of rajasthan whereas those in the cambay vastan rajpardi and tadkeshwar lignite seams saurashtra bhavnagar upper and lower lignite seams and kachchh matanomadh and panandhro lignite seams basins are located in gujarat the position of the cambay basin gujarat being closer to the equator during the early eocene period makes it pertinent to understand the variations in petrographic and geochemical constituents of gujarat and rajasthan lignites in space and time floral growth which largely depends on the climate of the region and its geographical location has an important role in the formation of mire nevertheless the peat forming plant communities nutrient supply bacterial activity types of deposition temperature ph and redox potential impart various characteristics to coal and are reflected in macerals black bands in gujarat and rajasthan lignites are strongly gelified compared to brownish bands and are stratified in nature they are dominantly composed of huminite maceral group while liptinites and inertinites occur in subordinated amount these lignites of gujarat and rajasthan have high values of gelification index gi and low tissue preservation index tpi indicating thereby a continuous presence of wet condition in the basin and slow subsidence rate however due to fluctuating water level in the basins few sections experienced relatively oxic episodes indicated by relatively high inertinite content study of the ground water index gwi and vegetation index vi of these lignites indicates rheotrophic to mesotrophic hydrological condition the study revealed that the lignites of rajasthan and gujarat were formed during the transgressive phase under coastal marshy setting however there were intermittent episodes of fluvial activities which gave rise to supratidal flood plains

small mammal carbon isotope ecology across the miocene pliocene boundary northwestern argentina abstract the late miocene expansion of plants using the c 4 photosynthetic pathway in south america has been documented by tooth enamel carbon isotope ratios 13 c en however a more detailed understanding of this ecological event is hampered by poor chronological control on the widespread fossil localities from which isotopic data are derived this study develops a 13 c en record from a single 2500 m thick stratigraphic section in subtropical south america strata at puerta de corral quemado pcq northwestern argentina span 9 to 3 5 ma in age and existing paleosol carbonate data 13 c pc document c 4 expansion across the miocene pliocene boundary comparison of 13 c en data with 13 c pc data at high stratigraphic resolution refines understanding of this ecological event in south america small mammal 13 c en data in particular are complementary to that of large mammal and paleosol 13 c data small mammal teeth integrate isotopic data over much shorter temporal and spatial scales than large mammal teeth providing a sensitive measure of local vegetation and placing constraints on the landscape distribution of c 3 and c 4 plants explicit consideration of the distinctive carbon isotope enrichment factor between enamel and diet for rodents e en diet 11 as opposed to 14 for large mammals allows for unequivocal inference of c 4 vegetation 1 ma prior to that inferred from large mammal 13 c en data and 2 ma prior to 13 c pc data this multiproxy record demonstrates that c 4 plants were a stable component of the ecosystem hundreds of thousands of years prior to their major ecological expansion and that the expansion of c 4 plants was pulsed at pcq two periods of ecological change are demonstrated by 13 c and 18 o data at 7 ma and 5 3 ma coincident with the miocene pliocene boundary development of small mammal 13 c en records on other continents may provide similar insight into the early stages of the global c 4 event

microfabric mineralogy and early diagenetic history of the whitby mudstone formation toarcian cleveland basin u k the whitby mudstone formation in northeast england contains three shale facies normal restricted and bituminous which have previously been differentiated on the basis of sedimentary structures and faunal assemblages this paper shows that the three facies can also be differentiated by mineralogical geochemical and microtextural criteria determined using bsem edxra xrd and xrf the bituminous shale facies consists of finely laminated shales containing an early diagenetic mineral assemblage dominated by pyrite calcite and dolomite the weakly laminated restricted facies shales contain an early diagenetic assemblage dominated by pyrite the normal facies shales are very weakly laminated and contain siderite in addition to pyrite the geochemical conditions which left a dominant early diagenetic imprint on the three facies are interpreted to be carbon rich sulphidic carbon poor sulphidic and very carbon poor sulphidic respectively

mass independent fractionation of mercury isotopes in the environment 1 the toxicity of mercury s methylated species and its biomagnification in aquatic food chains and global dispersion by the atmosphere are the cause of worldwide health problems recent reports have observed natural mass dependent fractionation in mercury isotopes and recent theoretical work has demonstrated that isotopic separation in mercury is due primarily to nuclear field shifts nuclear volume effect and the magnetic spin effect gives rise to mass independent fractionation mif of odd neutron number isotopes now we present analytical evidence of mass independent isotopic variations in mercury produced by both nuclear volume and magnetic isotope processes even mass number isotopes exhibit a pattern indistinguishable from that produced by mass dependent fractionation with both positive and negative 199hg and 201hg anomalies mif is easier to reliably determine in hg isotopes than mass dependent fractionation alone and thus it provides a potentially important key in constraining models of mercury sources and pathways in the environment

sedimentological and palaeohydrological responses to tectonics and climate in a small closed lacustrine system oligocene as pontes basin spain a small closed lacustrine system developed during the restraining overstep stages of the oligocene as pontes strike slip basin spain the increase in basin accommodation and the headward spread of the drainage which increased the water input triggered a change from shallow holomictic to deeper meromictic conditions the lower shallow lacustrine assemblage consists of mudstone carbonate cycles recording lacustrine palustrine ramp deposition in a saline lake high sr content in some early diagenetic calcites suggests that aragonite and calcite made up the primary carbonate muds early dolomitization took place together with widespread pedogenic activity the upper deep freshwater lacustrine assemblage includes bundles of carbonate clay rhythmites and fine grained turbidite beds primary calcite and diagenetic siderite make up the carbonate laminae the mg content of the primary carbonates records variations in mg ca ratios in lacustrine waters d 18 o and d 13 c covariance trends in calcite reinforce closed drainage conditions d 18 o data indicate that the lake system changed rapidly from short lived isotopically light periods i e from seasonal to pluriannual to longer steadystate periods of heavier d 18 o i e from pluriannual to millennial the small d 13 c changes in the covariant trends were caused by dilute inflow changing the contributions of dissolved organic carbon in the system and or internal variations in lacustrine organic productivity and recycling in both shallow and deep carbonate facies sulphate reduction and methanogenesis may account respectively for the larger negative and positive d 13 c shifts recorded in the early diagenetic carbonates calcite dolomite and siderite the lacustrine system was very susceptible to high frequency climatically forced water balance variations these climatic oscillations interfered with the lowfrequency tectonic and morphological changes in the basin catchment this resulted in the superposition of high order depositional mineralogical and geochemical cycles and rhythms on the lower order lacustrine infill sequence

evolution of the miocene sedimentary fill of the gediz graben sw turkey abstract the gediz graben is a continental extensional basin filled with miocene to recent sediments the evolution of the graben can be expressed in terms of two phases i miocene half graben phase and ii post miocene graben phase the miocene half graben phase was governed by the southern margin structure evolution of which significantly controlled the stratigraphic variability in the basin alluvial fluvial and lacustrine systems developed in the graben as a function of distance to the southern margin thus alluvial deposits with coarse grained facies dominate the southern margin and grade into finer fractions of fluvial and or lacustrine deposits to the north this depositional architecture repeated three times during the miocene and deposited alasehir caltilik and gediz formations these formations depict distinct thickness and grain size decrease from south to north to emphasize the half graben configuration for the favour of the southern margin the post miocene graben phase started with the faulting of the northern margin this resulted in relatively balanced partitioning of the subsidence between the two margins although the preceding asymmetry was inherited by the graben sediment influx became bipolar and alluvial fan systems developed along the both margins