is mid late paleozoic ocean water chemistry coupled with epeiric seawater isotope records isotopes of epeiric sea carbonates are used to construct seawater records for modeling global changes in paleozoic ocean chemistry climate and for intercontinental correlation we present for the first time geochemical results of paleozoic brachiopods biogenic low mg calcite blmc from open ocean permian carboniferous seamounts of japan situated in the tropical mid panthalassic ocean strontium isotope values of blmc from the panthalassic and paleotethys oceans are coupled with those of coeval specimens from epeiric seas of north america europe and russia p 0 393 but not with those of epeiric sea whole rocks matrix aragonite calcite mac p 0 029 and conodonts biogenic apatite ba p 0 031 oxygen isotope values of blmc from the panthalassic and paleotethys exhibit mixed results with studies of counterparts from epeiric seas p 0 596 reflecting overprinting of local environmental conditions on global trends carbon isotope values of blmc and mac from the panthalassic and paleotethys oceans are generally dissimilar to those of coeval material from epeiric seas of north america europe and russia p 0 001 and 0 002 respectively factors such as water mass stratification evaporation dilution depth temperature carbon burial and or oxidation variations and syndepositional diagenesis within the local environment probably influenced the chemistry of the fauna and accumulating sediments this decoupling of carbon and oxygen isotope values from the open ocean with those from epeiric seas makes questionable the use of isotope results from epeiric seas for international correlation constructing global seawater records determining fluxes in the global carbon cycle and for modeling climate changes and subsequently atmospheric carbon dioxide levels

the assessment of ree patterns and 143nd 144nd ratios in fish remains abstract the ree content and isotopic composition of sr and nd have been determined in fish teeth ranging in age from the trias to the present and from various localities mostly around the atlantic these measurements have been carried out on selachian and teleost remains from the same locality in togo and show no appreciable difference which suggests with the help of a mass balance calculation of the ce anomaly that diagenetic effects are not responsible for the ree enrichment of biogenic phosphates one group of fossil teeth has about 3 times the ree abundances of shale and a shale normalized pattern with a minimum at sm it is thought to reflect deposition in the open sea environment a second group has ree concentration about 10 times higher than the first group with either a regular light ree enrichment or more frequently a maximum in the middle ree both being probably indicative of deposition in estuarine or near shore conditions the shape of the ree spectra and the size of the ce anomaly can be used semi quantitatively to determine the depth of deposition the results presented here on late cretaceous eocene fish teeth samples from morocco reflect an increasing influx of deep waters with a lowla yb ratio and strong negative ce anomaly which agrees well with the evolution of sediment chemistry and microfauna associations in contrast nd is typical of the water mass in which the fish debris decayed examples of nearly isolated basins identified with nd isotopes include the south atlantic prior to the lutetian nd 13 5 the miocene persian gulf nd 3 1 and bolivia during the late cretaceous nd 12 8 togo and guinea bissau results suggest that in the south atlantic the meridional oceanic circulation had not started before 45 ma ago combination of ree and nd data suggests that the assignment of jurassic cretaceous samples measured so far to open sea water masses is still ambiguous

evaluation of the application of rare earth elements to paleoceanography anomalous departures of rare earth elements ree from similarity of chemical behaviour are most evident in a comparison of ce with its neighbors under reducing conditions ce3 acts like other ree but oxidized ce4 is adsorbed on mn fe oxyhydroxides or organic particulates and consequently the remaining solution will tend to exhibit a negative ce anomaly in addition more subtle fractionations may emphasize the light or the heavy or the middle ree a pattern of ree may be recorded by immediate diagenesis on a suitable chemical substrate such as apatite fish debris conodonts carbonate or chert this record was originally thought to reflect the paleoredox conditions of primary deposition however any such primary record may be overprinted by late diagenetic alteration early analyses of ree in conodonts from a wide range of sediments suggested a prevalence of reducing conditions no ce anomaly in pre carboniferous oceans and more common oxidation negative ce anomaly in the late paleozoic however recent research by other investigators indicates that variations in cean are more diverse in origin and in particular many are distorted to an unknown extent by late diagenesis in any case it is now clear that geological age does not show a consistent relationship to the level of the ce anomaly the ce anomaly apparently does not play any regular role in the isotopic events that accompany prominent mass extinctions further research is required to understand and thus make useful the controls on the ce anomaly

geochemistry of modern brachiopods applications and implications for oceanography and paleoceanography abstract modern rhynchonellida terebratulida thecideida and a few inarticulated brachiopods were collected live or soon after death at 30 locations from depths of 2 3940 m from the equator to high latitudes covering the atlantic pacific indian caribbean and mediterranean oceans seas well preserved fibers of the secondary layer combined with sr 450 1928 mg kg mn 1 199 mg kg and fe 1 610 mg kg contents confirm with few exceptions the excellent preservation of the modern brachiopod material evaluation of the stable isotope compositions was conducted on 276 specimens and on 374 published samples for a total database of 650 samples from 80 locations it revealed that oxygen isotope incorporation into shell calcite secondary layer of modern articulated brachiopods in most cases occurs in equilibrium with the ambient water and as such reflects surrounding environmental conditions thecideida as a group shallow water and low latitude incorporate oxygen isotopes 3 04 to 0 35 into shell calcite in equilibrium with their ambient water a large majority of genera and species of the terebratulida shallow water and low mid latitude also incorporate oxygen 2 30 to 3 48 into shell calcite in isotopic equilibrium with their surrounding water in contrast equilibrium incorporation of oxygen isotopes into shell calcite by the rhynchonellida is uncertain but a vital effect probably applies to the craniida the question of equilibrium disequilibrium incorporation of carbon isotopes into shell calcite of modern brachiopods remains unresolved at this time isotope compositions range up to 4 5 5 6 and 1 5 for 13 c and up to 5 5 5 9 and 0 3 for 18 o for shallow water low mid and high latitude brachiopods respectively strontium isotopes of modern brachiopods as expected show no significant variation with location latitude water depth temperature salinity and general water conditions once local habitat and ecological influences of fossil brachiopods from similar latitudes are considered their isotopic elemental values should be valuable diagenetic indicators and important oceanographic chemostratigraphic proxies

strontium isotopes and rare earth element geochemistry of hydrothermal carbonate deposits from lake tanganyika east africa at cape banza north tanganyika lake fluids and aragonite chimneys have been collected many times since the discovery of this sublacustrine field in 1987 this sampling has been investigated here for the sr isotopic compositions and the rare earth element features of the carbonates and a few fluid samples the 87sr 86sr ratios of the chimneys indicate that they have precipitated from a mixture of lake water more than 95 and hydrothermal fluids no zoning in the chimneys was detected with our sr data for the rare earth elements the situation is more complex the external walls of the chimneys are rare earth element poor la 500 ppb yb 200 ppb la yb 2 to 3 4 their shale normalised rare earth element patterns suggest that they are in equilibrium with the inferred carbonate depositing fluids the rare earth element concentrations of the internal walls of the chimneys are significantly light rare earth elements lree enriched with la contents sometimes up to 5 ppm we suggest that they contain more vent fluid rare earth elements than the external wall samples possibly adsorbed on the surface of growing crystals or simply hosted by impurities it was not possible to constrain the nature of these phases but the variations of the compositions of the internal wall materials of the active chimneys with time as well as data obtained on an inactive chimney indicate that this rare earth element excess is mobile partition coefficients were calculated between the external wall aragonite and carbonate depositing fluid the results are strikingly similar to the values obtained by sholkovitz and shen 1995 on coral aragonite and suggest that there is no significant biologic effect on the incorporation of rare earth elements into coral aragonite and that the various carbonate complexes involved me co3 complexes are the main lree carriers in seawater cantrell and byrne 1987 instead of me co3 2 in banza fluids have the same behaviour during aragonite precipitation

diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies an isotopic and ree study of cambrian phosphorites seawater rare earth element ree distributions show heavy ree enrichment and cerium depletion but these characteristics are only rarely found in ancient marine authigenic minerals such as carbonate fluorapatite and calcite this enigma may be due to changing ree distributions in seawater through time or to post depositional redistribution of ree differentiating between these two factors is however far from straightforward as their relative importance is likely to vary and evidence is often ambiguous in this article we present ree as well as strontium and sulphur isotope data for basal cambrian phosphorites of south china which confirm the emerging rule of thumb that granular phosphorites seldom reveal extreme departures from the seawater norm and tend to undergo therefore less diagenetic alteration of ree spectra than skeletal apatites and other phosphate types this study reveals stratigraphic trends in ce anomalies ce ce that could be taken to imply the preservation of a palaeoenvironmental signal however further investigation of our data shows that such trends in phosphorites can also be caused by post depositional alteration which tends to 1 increase ree contents 2 reverse ce depletion 3 alter eu anomalies and 4 concentrate preferentially the middle ree mree further alteration which may be due to weathering has led to hree depletion and positive la and y anomalies tetrad effect this is the first study where ceanom and phosphate bound sulphate s isotope values could be compared for one particular stratigraphic section which provides us with an additional tool for the interpretation of diagenetic redox conditions least altered phosphorites from meishucun that yield a strongly negative ceanom constrain early cambrian seawater 34s to about 33 we conclude that phosphorite ceanom primarily records variations in the local conditions of diagenesis while outlining some special cases in which diagenetic redox conditions may broadly reflect local bottom water redox conditions

pliocene and pleistocene biostratigraphic succession of transbaikalia with emphasis on small mammals this paper deals with the pliocene pleistocene and holocene mammalian faunas of the transbaikal area for which 15 successive mammalian faunas are recognized this review is based on the study of new paleontological materials obtained from several late cenozoic localities and reexamination of existing faunal data stratigraphically the oldest fauna is known as udunginian it contains mostly fossils of forest inhabitants and few arvicolids this fauna was replaced by the next pliocene hipparion assemblage known as the chikoi faunistic complex characterized by the dominance of forest steppe and open landscape inhabitants as well as by the abundance and diversity of rooted arvicolids the itantsinian complex is the following faunistic level of the late pliocene it is characterized by the first appearance of equus and spermophilus and by the presence of progressive taxa of rooted voles the early pleistocene fauna is characterized by the appearance and abundance of rootless arvicolids and by the continued existence of the latest rooted voles the middle pleistocene tologoi faunistic complex is distinguished from the preceding one by the disappearance of rooted voles the late pleistocene fauna featured a diversity of microtus taxa and an abundance of lasiopodomys and ochotona species the majority of the late pleistocene small mammals belong to recent species although some of them were distributed over a greater area at that time than at present

rare earth elements in seep carbonates as tracers of variable redox conditions at ancient hydrocarbon seeps marine hydrocarbon seeps are dynamic systems which are typically reflected in complex lithologies of limestones forming at these sites in order to test if seep limestones with their multiple generations of carbonate phases reflect variable redox conditions the rare earth element ree patterns of limestones from five ancient hydrocarbon seep localities hollard mound middle devonian iberg mississippian beauvoisin oxfordian canyon and satsop river oligocene and marmorito miocene have been investigated the total ree contents vary widely 0 3 43 7 p p m early microcrystalline phases tend to show higher contents than spatially associated later phases microspar sparite and blocky cement the shale normalized ree patterns of the carbonates show both negative and positive ce anomalies even for individual deposits suggesting that the redox conditions varied significantly it is apparent that in addition to anoxic conditions oxic conditions were common in some ancient seep environments intermittent oxygenation is presumed to have resulted from abrupt changes in fluid flow

chemical diagenesis of a multicomponent carbonate system 2 stable isotopes abstract this study examines the oxygen and carbon isotopic distribution in the brachiopods crinoids rugose corals and matrix cement from the mississippian burlington limestone iowa and missouri and the silurian read bay formation arctic canada the isotopic data can be reconciled with textural and trace element observations only if the 18o content of ancient oceans differed from that of the present oceans this postulated secular variation in the 18o content of seawater requires a separate evaluation of the mississippian and silurian carbonate components examination of the 18o content of the least altered low mg calcite fossil components of the two formations suggests that the 18o of mississippian seawater was on average about 1 5 lighter and that of silurian seawater was about 5 5 lighter than the 18o of present day ocean water the average diagenetic shift in 18o for the read bay formation which stabilized in a partly closed diagenetic phreatic meteoric system is about 1 for the original low mg calcite and about 2 for the original high mg calcite and aragonite components conversely for the burlington limestone which stabilized in an open diagenetic phreatic meteoric system the average diagenetic shift in 18o is about 3 for the original low mg calcite and about 4 f r the original high mg calcite components the 13c values of the originally low mg calcite or high mg calcite with less than 7 mole mgco3 brachiopods and rugose corals the originally high mg calcite crinoids and the originally aragonite lime mud of the burlington limestone and read bay formation are bimodally distributed this bimodal 13c distribution is independent of geologic age inferred original mineralogy of the component degree of diagenetic alteration and the type of diagenetic meteoric system with components from both the read bay formation and burlington limestone contributing to both 13c groups the mode of the light 13c group is 0 25 and for the heavy 13c group it is 3 25 pdb both 13c groups also show a decrease in 13c of about 1 with increasing diagenetic alteration stabilization

carbon oxygen and strontium isotopes in paleozoic carbonate components an evaluation of original seawater chemistry proxies abstract brachiopods trilobites cements and whole rock matrix material were evaluated for their reliability as proxies of original seawater carbon oxygen and strontium isotope chemistry in this process coeval material was evaluated from individual horizons of formations spanning the permian to cambrian unaltered shells of low mg calcite articulated brachiopods retain original seawater oxygen carbon and strontium isotope compositions as old as late ordovician assessments of older specimens are hampered by a lack of suitable material coeval brachiopod whole rock sets a definitive assessment of cement marine chemistry is difficult due to the paucity of material but despite this caveat cements hold some promise for retaining original carbon and possibly strontium isotope seawater values in contrast the potential of whole rock material as a proxy of original seawater chemistry is quite complex in some but not all instances the carbon isotopic composition of whole rock after detailed scrutiny and evaluation appears to represent an original seawater chemistry signal in a few instances their oxygen isotope compositions reflect original seawater values unlike the stable isotope compositions the strontium isotopes of all studied whole rock material permian to upper cambrian appear not to reflect original seawater chemistry values thus the potential for retaining original seawater isotope chemistry and serving as specific proxies in order of decreasing reliability are 1 unaltered low mg calcite brachiopods c o and sr isotopes 2 pristine marine cements c and sr isotopes and 3 whole rock material c isotopes carbon oxygen and strontium isotope compositions of ordovician trilobites mirror those of coeval unaltered brachiopods cambrian trilobites hold significant promise as an important proxy of original seawater isotope chemistry but further studies are needed to ascertain their full potential the survey of isotopes in some ordovician and cambrian intermediate low mg calcite trilobites demonstrates their potential as an important proxy of original seawater chemistry

rare earth element evolution of phanerozoic seawater recorded in biogenic apatites rare earth element ree contents of marine biogenic apatites have been shown to record seawater compositions a data base of available and newly acquired rare earth element ree contents of marine biogenic apatites has been created to assess the past seawater ree compositions to ensure that this data base contains only the pristine ree signals altered samples characterized by very low la sm n ratios where n stands for ree ratios normalized to the nasc composition gromet et al 1984 geochim cosmochim acta 48 1984 2469 acquired during apatite recrystallization are not included in the database these data reveal a change in the tethyan seawater composition between 110 and 80 ma after the end of the cretaceous the ree chemistry of seawater remains constant until present day this seawater composition change is likely due to concurrent changes in ree scavenging processes a strong correlation between decreasing sm yb n ratios and increasing ce anomalies for samples deposited during the 80 110 ma period is observed as ce anomalies are attributed to ocean water redox conditions changes in ree scavenging could reflect an evolution from stratified and poorly oxygenated waters towards well mixed and oxygenated waters this could have resulted from changing current patterns stemming from the contemporaneous opening of the atlantic ocean a major change in middle and late cretaceous oceanic circulation linked to plate tectonics would have favored the colonization of pelagic environments

determination of both chemical and stable isotope composition in milligramme size carbonate samples abstract isotopic analysis of carbonates involves dissolution of the sample in 100 phosphoric acid analysis of the acid after reaction using inductive coupled plasma source spectrometry gives the chemical composition of the same sample molar fractions of cations in carbonate minerals can be determined to about 0 1 for ca 0 04 for mg 0 06 for fe 60 ppm for mn and 90 ppm for sr even the minor carbonate component in shales can be analyzed if a correction for leaching of clay minerals is made by reference to the al content of the solution however loss in accuracy ensues because of the uncertainty in the correction

early middle pleistocene transitions linking terrestrial and marine realms abstract marked by a progressive increase in the amplitude of climate oscillations an evolving waveform and a shift towards a quasi 100 ky frequency the early middle pleistocene transition empt previously known as the mid pleistocene transition or mid pleistocene revolution 1 4 0 4 ma represents a fundamental transformation in the earth s climate state the empt began with a substantial change in climate dynamics and ended with the mid brunhes event signaling the establishment of a new steady state the reasons for the empt while uncertain appear to involve a non linear response of the earth climate system the physical and biotic responses to this transition amplified by the growth of northern hemisphere ice sheets have been profound two important chronostratigraphic markers characterize the empt the jaramillo subchron 1 070 0 988 ma and the matuyama brunhes chron boundary 773 ka the latter has been chosen as the primary guide for the lower middle pleistocene subseries boundary as it lies at the approximate midpoint of the empt and aids in global recognition both in marine and terrestrial deposits the jaramillo subchron has received less attention but the late early pleistocene is important in europe because it saw the progressive transition from the villafranchian to galerian mammal faunas and expansion of hominins into western and northern europe the jaramillo subchron is represented by marine isotope stages mis 31 to 28 with mis 30 already showing the asymmetrical sawtooth pattern characteristic of the middle pleistocene indeed while variation in the 40 ky band obliquity remains strong throughout the empt low frequency variability begins at around 1250 1200 ky which coincides with a progressive increase in global ice volume against a backdrop of increasingly severe glacial cycles notably during mis 36 34 24 22 the so called 0 9 ma event 16 and 12 pronounced phases of warming are also documented globally including the super interglacial mis 31 the early phase of the empt is characterized by important glaciations beginning with mis 36 and continuing to mis 24 22 a major intensification of the east asian monsoon system intensification of loess deposition in northern europe development of open landscapes in western siberia increased fluvial incision higher amplitude sea level change and spread of large mammals across northern eurasia and a strong reduction in the north atlantic thermohaline circulation in europe the loss of thermophilous plant taxa during the empt and indeed throughout the quaternary is a reminder of the progressive cooling that took place here and elsewhere

paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite abstract rare earth element concentrations in biogenic apatite of conodonts fish debris and inarticulate brachiopods were determined in over 200 samples from cambrian to modern sediments tests for experimental bias caused by the chemicals used to separate fossils from the rock matrix and for interlaboratory interexperiment or interspecies related variations clearly show that no resolvable fractionation of ree occurs incorporation of ree in biogenic apatite of recent fish debris occurs near the sediment water interface soon after deposition and reflects characteristics of seawater the original ree signature apparently survives subsequent burial and diagenesis cerium variations in fish debris from modern environments are controlled by redox potential ce is fractionated by co precipitation with metallic oxides under oxidizing conditions this fractionation produces a negative ce anomaly ce anom in seawater that is reflected in the sedimented fish debris conversely no fractionation of ce occurs under reducing conditions resulting in ce concentrations that are normal to enriched in anoxic seawater and fish debris deposited under local or basinwide anoxic conditions extrapolation of observations of the redox control of ce anom in modern oceans to fossil apatite indicates that anoxic conditions were prevalent in lower paleozoic and lower triassic oceans whereas in the upper paleozoic the world ocean was generally oxidizing

crystal chemical controls on rare earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions abstract fossil biogenic apatites display rare earth element ree patterns which have been proposed to reflect environmental and biological controls on past seawater composition these patterns can be separated in two groups 1 patterns that are similar to those of open ocean and epicontinental waters and 2 patterns that exhibit a strong enrichment in intermediate ree bell shaped patterns because ree trapping in biogenic apatites occurs mostly post mortem it is essential to understand the crystal chemical inorganic factors that can influence the fractionation of ree between apatite and water a model is proposed by which partition coefficients of ree between apatite and water for a substitution mechanism can be extrapolated from mineral melt partition data to seawater or sedimentary basin conditions these are compared with available experimental partition coefficients for ree adsorption mechanism and used to discuss ree patterns in fossil biogenic apatites calculations of ree patterns for apatites at equilibrium with water show that the bell shaped patterns in fossil apatites can be explained by fractionation with seawater or continental fluids at low temperature under crystal chemical control involving a substitution mechanism and in the context of extensive or late diagenesis in that case the equilibrium composition of the fluid cannot be unequivocally determined from observed ree concentrations in fossil apatites this type of sample is inappropriate to discuss the past environmental or biological controls on ree concentrations in the ocean other sample compositions suggest little to moderate alteration of the original oceanic to freshwater pattern through the adsorption mechanism in the context of weak or early diagenesis and may be used with caution for that purpose

interoceanic variation in the rare earth major and trace element depositional chemistry of chert perspectives gained from the dsdp and odp record rare earth element ree major and trace element abundances and relative fractionations in forty nodular cherts sampled by the deep sea drilling project dsdp and ocean drilling program odp indicate that the ree composition of chert records the interplay between terrigenous sources and scavenging from the local seawater major and non ree trace element ratios indicate that the aluminosilicate fraction within the chert is similar to nasc north american shale composite with average pacific chert including 7 nasc like particles indian chert 11 nasc atlantic chert 17 nasc and southern high latitude shl chert 53 nasc using la as a proxy for ree approximations of laex the amount of la in excess of that supplied by the detrital aluminosilicate fraction indicate that pacific chert contains the greatest laex 85 of latotal and shl chert the least 38 of latotal as shown by interelement associations this laex is most likely an adsorbed component onto aluminosilicate and phosphatic phases accordingly chert from the large pacific ocean where deposition occurs relatively removed from significant terrigenous input records a depositional ree signal dominated by adsorption of dissolved rees from seawater pacific chert cece 1 and lanybn 0 8 1 resulting from adsorption of local ce depleted seawater and preferential adsorption of lrees from seawater e g lanybn 0 4 which increases the lanybn ratio recorded in chert chert from the atlantic basin a moderately sized ocean basin lined by passive margins and with more terrigenous input than the pacific records a mix of adsorptive and terrigenous ree signals with moderately negative ce anomalies and lanybn ratios intermediate to those of the pacific and those of terrigenous input chert from the shl region is dominated by the large terrigenous input on the antarctic passive margin with inherited cece 1 and inherited lanybn values of 1 2 1 4 cece does not vary with age either throughout the entire data base or within a particular basin overall cece does not correlate with p2o5 concentrations even though phosphatic phases may be an important ree carrier this and previous studies of the large scale controlling parameters of sedimentary rees across ocean basins collectively indicate that ree indices of depositional regime e g cece lanybn laex are reproducible in a variety of sediment and rock lithologies ages and ocean basins and present a coherent tool for paleoceanographic and tectonic basin reconstructions

the incorporation of rare earth elements in modern coral we report measurements of rare earth elements rees which show that these trace elements are being incorporated in modern coral in proportion to their seawater concentrations four bermuda north rock coral species diploria strigosa diploria labyrinthiformis montastrea annularis and porites astreoides and two tarawa atoll samples of the species hydnophora microconos were analyzed by ti idms following cleaning techniques to isolate the lattice bound rees based on the replicate analyses of the same piece of diploria strigosa excellent reproducibility was achieved the ree ca ratios 0 1 3 nmol mol of the bermuda and tarawa corals are similar to those of cd ca the trace metal with the lowest seawater concentration used in coral studies with the exception of ce the distribution coefficients e g dnd nd coral nd seawater ca seawater ca coral between bermuda coral lattice and sargasso seawater have fairly flat patterns across the ree series the values of d range from 1 to 3 like those reported for other trace elements in corals this suggests but does not prove that rees are incorporated in the aragonite lattice of these corals the shale normalized ree patterns of the tarawa corals also have seawater like distributions however no local seawater data are available to calculate values of d two bermuda species d labyrinthiformis and p astreoides have values of d for ce that are high with respect to the d values of la and nd implying that there is preferential uptake of ce into the lattice this may be related to the fact that ce is the only ree with an active redox chemistry in seawater there is considerable interest in using the chemical and isotopic composition of coral as indicators of climatic variations the combination of ree ca ratios and neodymium isotopic composition of coral has the potential to help understand important natural processes a primary application could be directed toward a tracer for river water discharge in tropical regions and by inference a proxy for rainfall climate variation and weathering history this application would exploit the fractionated composition of rees in river water as a terrigenous signature in coastal corals

changes in the fossil mammal faunas of western transbaikalia during the pliocene pleistocene boundary and the early middle pleistocene transition abstract the faunal variations sedimentary evolution and successive changes in vegetation during the late pliocene through the middle pleistocene of the western transbaikal area were analyzed to ascertain the main events on the pliocene pleistocene boundary and to trace the early middle pleistocene transition the evolutionary development of the main characteristic small mammals and their phyletic lineages involved replacement of the itantsinian fauna by the dodogolian assemblage in the west transbaikalia the pliocene pleistocene boundary is recognized between the late pliocene itantsinian and the early pleistocene dodogolian faunas biostratigraphic studies on small mammals have revealed that the early middle pleistocene transition can be placed at the brunhes matuyama paleomagnetic boundary 0 78 ma which is determined in the middle sequence of the tologoi key section between the latest early pleistocene fauna of the tologoi 2 1 and 2 2 and middle pleistocene fauna of tologoi complex tologoi 2 4 and 2 5

a new species of the extinct vole villanyia from renzidong cave anhui east china with discussion on related species from china and transbaikalia a new species of extinct vole with rooted cementless molars is described on the basis of abundant remains from the early pleistocene late pliocene sediments of renzidong cave among the extinct cementless voles distinction between villanyia and borsodia is recommended to determine the generic allocation of the new species the comparison of diagnostic characters of these two genera obtained by this study indicates that the new species belongs to villanyia and the species is named as v fanchangensis the provided revision of the chinese and transbaikalian species of villanyia and borsodia has revealed that the species of villanyia were distributed in southern china during the late pliocene and in transbaikalia during the middle pliocene in china villanyia was replaced by borsodia in the earliest pleistocene while in transbaikalia it was replaced by borsodia in the late pliocene c 2007 published by elsevier ltd

biogenic and abiogenic low mg calcite blmc and almc evaluation of seawater ree composition water masses and carbonate diagenesis the ree and shale normalized paas reesn values of modern brachiopods biogenic low mg calcite blmc represented by several species from high to low latitudes from shallow to deep waters and from warm and cold water environments define three distinct average seawater trends the warm and cold water brachiopods define two indistinguishable p 0 050 groups that mimic open ocean seawater ree chemistry exhibiting the typical lree enrichment with a slightly positive to negative ce anomaly followed by an otherwise invariant series other recent brachiopods from an essentially siliciclastic seabed environment are distinct in both ree and reesn trends from the previous two populations showing a slight enrichment in the mrees and an increasing trend in the hrees other groups of modern brachiopods are characterized by elevated reesn trends relative to the normal groups as well as by complexity of the series trends the most characteristic feature is the decrease in the hrees in these brachiopods from areas of unusual productivity i e such as upwelling currents fluvial input and aerosol dust deposition preserved brachiopods from the eocene and silurian exhibit reesn trends and ce anomalies similar to that of the open ocean modern brachiopods although their enriched ree concentrations suggest precipitation of blmc influenced by extrinsic environmental conditions preservation of the blmc was tested by comparing the ree and reesn trends of preserved eocene brachiopods to those of oligocene brachiopods that were altered in an open diagenetic system in the presence of phreatic meteoric water the altered blmc is enriched by approximately one order of magnitude in both ree and reesn trends relative to that in blmc of their preserved counterparts similarly the ree and reesn of preserved silurian brachiopod blmc were compared to those of their enclosing altered lime mudstone which exhibits features of partly closed system phreatic meteoric water diagenesis despite these differences in the diagenetic alteration systems and processes the rees and reesn trends of the blmc of altered brachiopods and of originally mixed mineralogy lime mudstones now diagenetic low mg calcite are enriched by about one order of magnitude relative to those observed in the coeval and preserved blmc in contrast to the changes in ree and reesn of carbonates exposed to phreatic meteoric water diagenesis are the ree compositions of late burial calcite cements precipitated in diagenetically open systems from burial fluids the ree and reesn trends of the burial cements mimic those of their host lime mudstone with all showing slight lree enrichment and slight hree depletion exhibiting a chevron pattern of the reesn trends the overall enrichment or depletion of the cement reesn trends relative to that of their respective host rock material reflects not only the openness of the diagenetic system but also strong differences in the elemental and ree compositions of the burial fluids evaluation of the ce ce sn and la pr pr sn anomalies suggests precipitation of the burial calcite cements essentially in equilibrium with their source fluids

rare earth element contents of jurassic fish and reptile teeth and their potential relation to seawater composition anglo paris basin france and england the rare earth element ree chemistry of jurassic shelf seawater from western europe anglo paris basin was investigated by analyzing the fish and reptile teeth deposited in shallow to deeper water 200 m environments ree patterns in apatites are controlled by the host sediments vertebrate teeth sampled from the siliciclastic sediments calcareous sandstones and shales show flat shale normalized ree patterns that reflect the dominant influence of the continental source from which the ree were derived carbonate deposits protected from the clastic sources contain fish and reptile teeth whose ree patterns reflect more accurately the ree composition of the overlying water column the ree patterns are similar through the bajocian to the oxfordian and are characterized by a depletion in heavy rare earth element dy ybn 1 8 5 0 compared to modern seawater compositions dy ybn 0 8 0 9 the fractionations among hree in the jurassic seawater are more efficient than in modern oceans and increases with depth instead of decreasing these hree removal processes operated as early as the paleozoic and disappeared during the late cretaceous the fractionation of hree relative to lree is correlated with the increasing depth of the basin as indicated by two independent criteria that are the sedimentary structures and the oxygen isotope composition of coexisting brachiopods the dy ybn ratio of the marine biogenic phosphates can be used as a proxy of paleo water depths at the scale of a water mass ce anomalies ce in biogenic apatite bearing limestones are variable and systematically negative relative to modern surface seawater and bathonian values mean ce 0 63 0 10 weak ce anomalies during the callovian mean ce 0 21 0 09 suggest the onset of more reducing conditions this redox change coincided with an increase of seawater temperatures as suggested by the oxygen isotope compositions measured on the same teeth we speculated that the callovian low ce could result from a decrease in the po2 due to the warming of seawater

tologoi key section a unique archive for pliocene pleistocene paleoenvironment dynamics of transbaikalia bikal rift zone abstract the multi layered key section of tologoi is situated on the selenga river left bank 15 km southwest of ulan ude city 51o45 n 107o29 e in the western transbaikal region it holds a long record of quaternary sedimentation since early late pliocene through holocene with the only minor gap in the beginning of early pleistocene comprehensive studies have been carried out on the lithology geochemistry fauna succession and paleoenvironment reconstructions this paper summarizes the data acquired on the geology and stratigraphy of the tologoi section the authors investigated the composition structure and formation conditions of the section as well as the intensity of weathering rock geochemistry grain size and biostratigraphy

early middle pleistocene transitions an overview and recommendation for the defining boundary the early middle pleistocene transition c 1 2 0 5 ma sometimes known as the mid pleistocene revolution represents a major episode in earth history low amplitude 41 ka obliq uity forced climate cycles of the earlier pleistocene were replaced progressively in the later pleistocene by high amplitude 100 ka cycles these later cycles are indicative of slow ice build up and subsequent rapid melting and imply a transition to a strongly non linear forced climate system changes were accompanied by substantially increased global ice volume at 940 ka these climate transformations particularly the increasing severity and duration of cold stages have had a pro found effect on the biota and the physical landscape especially in the northern hemisphere this review assesses and integrates the marine and terrestrial evidence for change across this transition based on the literature and especially the following 17 chapters in the present volume orbital and non orbital climate forcing palaeoceanography stable isotopes organic geochemistry marine micropalaeontology glacial history loess palaeosol sequences pollen analysis large and small mammal palaeoecology and stratigraphy and human evolution and dispersal are all considered and a series of discrete events is identified from marine isotope stage mis 36 c 1 2 ma to mis 13 c 540 460 ma of these the cold mis 22 c 880 870 ka is perhaps the most profound however we here endorse earlier views that on practical grounds the matuyama brunhes palaeomagnetic chron boundary mid point at 773 ka with an estimated duration of 7 ka would serve as the best overall guide for establishing the early middle pleistocene subseries boundary

rare earth geochemistry of phosphorites abstract the abundance of rare earth elements ree s in francolite increases with increasing age as a result of post depositional enrichment abundances are higher in pelletal samples than in non pelletal ones because the higher surface mass ratio of pelletal francolite promotes enrichment during diagenesis onshore francolite has higher ree abundances than that found offshore distribution patterns in francolite may be similar to those reported for open ocean water or shale depending upon the dominant source of the ree s different patterns result from weathering and deep burial diagenetic modification of the original patterns and abundances negative ce anomalies occur in francolites containing structural sulphur that is isotopically indistinguishable from seawater of the same age zero or positive anomalies occur in francolites which contain sulphur that is isotopically lighter than seawater

sm nd in marine carbonates and phosphates implications for nd isotopes in seawater and crustal ages this study explores the possibility of establishing nd isotopic variations in seawater over geologic time calcite aragonite and apatite are examined as possible phases recording seawater values of nd modern biogenic and inorganically precipitated calcite and aragonite from marine environments were found to have nd concentrations of from 0 2 to 70 ppb showing that primary marine caco 3 contains little ree and that nd ca is not greatly enhanced relative to seawater during carbonate precipitation very young marine limestone and dolomite containing no continental detritus have 200 ppb nd all the carbonates are lree enriched 0 16 sm nd 0 45 modern and very young atlantic and pacific carbonates have nd in the range of shallow atlantic and pacific seawater respectively implying that they derive their ree from local seawater the nd in well preserved carbonate fossils is 4 10 4 ppb much greater than in their modern counterparts but like the high values found for carbonates in other studies we believe the high ree contents at the 500 ppb level in some detritusfree carbonates are due to ree rich fe hydroxide in on the carbonate in favorable cases such material may record seawater nd values however introduction of extraneous ree may obscure the original isotopic composition of pure caco 3 because of its very low intrinsic primary ree abundance modern biogenic apatite is also shown to have very low ree content 150 ppb nd but appears to quickly scavenge ree from seawater inorganically precipitated apatite from phosphorites has high concentrations of seawater derived ree young phosphorite apatite from the atlantic and pacific oceans has nd in the range of the seawater from these oceans older apatite samples of similar age from different localities bordering common oceans record similar values of nd t sedimentary apatite has sr t values in good agreement with the curves for 87 sr 86 sr of seawater as a function of time individual conodonts from a single formation yield the same sr t and nd t other workers have shown that sedimentary apatite preserves seawater ree patterns these characteristics suggest that sedimentary apatite can be used to determine nd t in ancient seawater the seawater values so inferred range between 1 7 and 8 9 over the last 700 my and lie in the range of modern seawater showing no evidence for drastic changes high values of seawater nd t in the triassic and latest precambrian may correlate with the breakup of large continental landmasses the initial nd t 15 0 of a 2 ae old phosphorite implies the presence of 1 5 ae old continental crust at 2 ae ago the approach outlined here can be used to constrain the age of the exposed crust as a function of time

dolomitization of the lower ordovician aguathuna formation carbonates port au port peninsula western newfoundland canada implications for a hydrocarbon reservoir the lower ordovician aguathuna formation 100 m thick is formed of shallow marine carbonates which constitute the uppermost part of the st george group of western newfoundland sedimentation wa

late miocene ductile extension and detachment faulting mykonos greece the geometry and style of structural relations at map to microscopic scale on mykonos cyclades aegean sea greece suggests ductile extension and detachment faulting during the late miocene this island is dominated by granitic rocks that have a well developed shallowly dipping mylonitic foliation and a northeast southwest trending mineral elongation lineation kinematic indicators in these rocks exhibit a top to the northeast down dip sense of shear textural relations suggest that conditions during mylonitic deformation were greenschist to amphibolite facies and published k ar geochronology suggests a late miocene age for this deformation event mylonitic rocks lie in the footwall of a low angle fault and fault striae parallel to the elongation lineation suggest kinematic coordination between mylonitic deformation and movement along the fault translation along the fault juxtaposes younger tilted sedimentary rocks of low metamorphic grade upon the once deeper mylonitic rocks the style and geometry of deformational fabrics and map relations on this island are strikingly similar to those observed in metamorphic core complexes of the western united states