a review and synthesis of glendonites pseudomorphs after ikaite with new data assessing applicability as recorders of ancient coldwater conditions abstract calcite pseudomorphs after ikaite glendonite are associated with coldwater depositional systems including glaciomarine and deepwater settings as dictated by the limited stability field of ikaite ikaite precipitation is favored by elevated alkalinity and dissolved phosphate conditions encountered commonly in association with organic rich marine sediments where methane oxidation is occurring the rapid recrystallization of ikaite to calcite during slight warming or pressure release results in considerable solid volume loss producing a highly porous crystal mesh preservation of the original ikaite crystal form requires precipitation of diagenetic calcite cement during early burial to prevent compaction and collapse of pseudomorph structures during later burial diagenesis remaining pore space may be filled with deeper burial calcite cement glendonites from the permian of the sydney basin occur in subtidal shelf facies containing glacial dropstones and a normal marine fauna stable oxygen isotope signatures of modern ikaite suggest carbonate precipitation in equilibrium with ambient seawater carbon signatures are usually strongly negative relative to normal marine carbonate consistent with derivation of carbonate from methane oxidation review of published data suggests that while holocene glendonite may provide reliable isotopic records of the conditions of ikaite precipitation precipitation of later calcite cement within the glendonite structure reduces the significance of the isotopic signature as an indicator of primary depositional conditions bulk glendonite samples from the permian sydney basin australia have a broad range of 18 o and 13c 18opdb 5 to 15 13c 8 to 16 in contrast to the narrow range for brachiopod carbonate 18opdb 1 to 5 13c 5 to 7 from the same strata handpicked separates of primary glendonite and secondary calcite also have a wide range of stable isotope values the data from sydney basin glendonites indicate that diagenetic precipitation of calcite has blurred the isotopic signature of primary ikaite replacement calcite at the scale of micosampling done in this study

post processing removal of correlated errors in grace data 1 gravity fields produced by the gravity recovery and climate experiment grace satellite mission require smoothing to reduce the effects of errors present in short wavelength components as the smoothing radius decreases these errors manifest themselves in maps of surface mass variability as long linear features generally oriented north to south i e stripes the presence of stripes implies correlations in the gravity field coefficients here we examine the spectral signature of these correlated errors and present a method to remove them finally we apply the filter to a model of surface mass variability to show that the filter has relatively little degradation of the underlying geophysical signals we seek to recover

ice age at the middle late jurassic transition a detailed record of sea surface temperatures in the northern hemisphere based on migration of marine invertebrate fauna ammonites and isotopic thermometry 18o values of shark tooth enamel indicates a severe cooling at the middle late jurassic transition mljt about 160 ma ago the magnitude of refrigeration 1 3 c for lower middle latitudes and its coincidence in time with an abrupt global scale fall of sea level documented through sequence stratigraphy are both suggestive of continental ice formation at this time ice sheets may have developed over the high latitude mountainous regions of far east russia the drastic cooling just post dated the middle late callovian widespread deposition of organic rich marine sediments e g northwestern europe central atlantic and arabian peninsula this thermal deterioration can thus be ascribed to a downdraw in atmospheric co2 via enhanced organic carbon burial which acted as a negative feedback effect i e the inverse greenhouse effect the glacial episode of the mljt climaxed in the late callovian lasted about 2 6 myr and had a pronounced asymmetrical pattern composed of an abrupt 0 8 myr temperature fall opposed to a long term 1 8 myr stepwise recovery the glacial conditions at the mljt reveal that atmospheric co2 levels could have dropped temporarily to values lower than 500 ppmv during mesozoic times

methods for inferring regional surface mass anomalies from gravity recovery and climate experiment grace measurements of time variable gravity 1 the gravity recovery and climate experiment grace will deliver monthly averages of the spherical harmonic coefficients describing the earth s gravity field from which we expect to infer time variable changes in mass averaged over arbitrary regions having length scales of a few hundred kilometers and larger to accuracies of better than 1 cm of equivalent water thickness these data will be useful for examining changes in the distribution of water in the ocean in snow and ice on polar ice sheets and in continental water and snow storage we describe methods of extracting regional mass anomalies from grace gravity coefficients spatial averaging kernels were created to isolate the gravity signal of individual regions while simultaneously minimizing the effects of grace observational errors and contamination from surrounding glacial hydrological and oceanic gravity signals we then estimated the probable accuracy of averaging kernels for regions of arbitrary shape and size

diagenesis of aragonite from upper cretaceous ammonites a geochemical case study shell aragonite from ammonites collected in the upper cretaceous of west greenland was investigated by means of macroscopic microscopic visual evaluation analyses of calcite aragonite ratios carbon and oxygen isotopic compositions and sr and mg concentrations of shell carbonate and of amino acid compositions of organic matrices the results are 1 material visually classified as well preserved may have suffered diagenetic modifications of mineralogical and chemical composition 2 of the chemical and mineralogical parameters studied amino acid composition calcite aragonite ratios and magnesium concentrations were found to be most sensitive to post depositional modifications while oxygen isotope composition and strontium concentrations showed detectable diagenetic modifications only after more pronounced alterations 3 based on the mg ca ratios and calcite concentrations of the shell aragonite a diagenetic classification has been proposed grouping the material into well preserved moderately preserved and poorly preserved 4 the chemical and mineralogical composition of the best preserved material suggests that the upper cretaceous ammonites had a shell composition similar to that of modern nautilus and other aragonite shelled molluscs

cathodoluminescene at low fe and mn concentrations a sims study of zones in natural calcites abstract point analyses of natural calcite cements by sims confirm the earlier suggestions that 20 ppm mn is required to activate luminescence whereas fe concentrations in excess of 1400 ppm quench it partly independently of the mn content below this fe threshold luminescence is bright at mn concentrations in excess of 225 ppm in the range 20 225 mn all types of luminescence dull luminescent and nonluminescent can occur this undifferentiated domain is evident also from a compilation of literature data the type of luminescence is not a simple function of fe and mn concentrations other parameters influence cl sinc most diagenetic calcite cements have fe and mn concentrations that place them within the field of mixed cathodoluminescence these results force reassessment of models that equate the type of luminescence with the redox state of the diagenetic environment

lower jurassic lower cretaceous belemnite biogeography and the development of the mesozoic boreal realm abstract the distribution of lower jurassic lower cretaceous belemnites is reviewed in the light of recent taxonomic and biogeographic studies and it is seen that belemnite provinciality developed in the late lower jurassic when distinct arctic taxa are first recognised in the middle jurassic boreal and tethyan belemnite realms are apparent the boreal realm being divisable into informal boreal atlantic and arctic provinces which can be recognised up into the lower cretaceous in the upper jurassic and lower cretaceous distinct arctic belemnites are found in association with tethyan ammonites in california and it is this factor in association with an observed increase in belemnite diversity northwards from the boreal atlantic to the arctic provinces that suggests that latitudinal temperature gradients were not the overall control influencing the development of boreal and tethyan belemnite realms instead the hostile environment of the boreal atlantic area the european archipelago is seen as an effective barrier to the migration of tethyan belemnites to the arctic and vice versa however high sea level stands may have helped blur these distinctions as in the late valanginian hauterivian when arctic taxa invaded europe and tethyan taxa the periphery of the arctic basin

grace measurements of mass variability in the earth system monthly gravity field estimates made by the twin gravity recovery and climate experiment grace satellites have a geoid height accuracy of 2 to 3 millimeters at a spatial resolution as small as 400 kilometers the annual cycle in the geoid variations up to 10 millimeters in some regions peaked predominantly in the spring and fall seasons geoid variations observed over south america that can be largely attributed to surface water and groundwater changes show a clear separation between the large amazon watershed and the smaller watersheds to the north such observations will help hydrologists to connect processes at traditional length scales tens of kilometers or less to those at regional and global scales

characteristic precipitation patterns of el nino la nina in time variable gravity fields by grace article i nfo el nino and la nina are known to bring about characteristic patterns of anomalous precipitation in various regions of the world we extracted temporary and regional gravity changes from monthly gravity fields recovered by the grace satellites and converted them to the changes in surface mass possibly ground or subsurface water in land area such mass changes in the 2006 2007 el nino and 2005 2006 la nina episodes agreed well with precipitation anomaly patterns inferred from meteorological records in tens of past such episodes we further compared them with anomalies of soil moisture numerically simulated by integrating monthly precipitation and evapotranspiration they agree quantitatively with the grace data suggesting that temporal changes in terrestrial water storage in low latitude region are largely governed by precipitation this study demonstrates the potential of satellite gravimetry as a sensor of inter annual climate changes

stable isotopic studies of nautilus macromphalus sowerby new caledonia and nautilus pompilius l fiji abstract two specimens of nautilus macromphalus sowerby from new caledonia and two specimens of nautilus pompilius l from fiji have been selected for stable isotope analysis of all septa these animals were captured at depths of 80 m and 200 m respectively the early formed septa were also analyzed from three additional specimens of n macromphalus captured in new caledonia at 300 400 m oxygen isotope compositions of septa from both populations are characterized by 1 an abrupt increase in su18o of 1 3 5 from septa 6 to 8 and 2 septum to septum variations in 13 and 18o which are roughly sympathetic and larger for carbon than oxygen septa from the fiji specimens are slightly depleted in 18o relative to those from new caledonia the isotopic step between septa 7 and 8 is interpreted to record the hatching of the embryo after development of the seventh septum marked 18o depletion of septa 1 7 evidently reflect non equilibrium metabolic isotope fractionation during embryonic groth stages or perhaps more likely a difference in the isotopic compositions of nepionic fluid and sea water the oxygen isotope compositions of septa 10 and higher and shell walls appear to closely approach isotopic equilibrium with sea water as demonstrated by a comparison of calculated isotopic and known temperatures for aragonite precipitation by an aquarium grown specimen a slightly warmer average environment of growth is indicated for the fiji samples

time variability of the earth s gravity field hydrological and oceanic effects and their possible detection using grace the grace satellite mission scheduled for launch in 2001 is designed to map out the earth s gravity field to high accuracy every 2 4 weeks over a nominal lifetime of 5 years changes in the gravity field are caused by the redistribution of mass within the earth and on or above its surface grace will thus be able to constrain processes that involve mass redistribution in this paper we use output from hydrological oceanographic and atmospheric models to estimate the variability in the gravity field i e in the geoid due to those sources we develop a method for constructing surface mass estimates from the grace gravity coefficients we show the results of simulations where we use synthetic grace gravity data constructed by combining estimated geophysical signals and simulated grace measurement errors to attempt to recover hydrological and oceanographic signals we show that grace may be able to recover changes in continental water storage and in seafloor pressure at scales of a few hundred kilometers and larger and at timescales of a few weeks and longer with accuracies approaching 2 mm in water thickness over land and 0 1 mbar or better in seafloor pressure

time variable gravity from grace first results eleven monthly grace gravity field solutions are now available for analyses we show those fields can be used to recover monthly changes in water storage both on land and in the ocean to accuracies of 1 5 cm of water thickness when smoothed over 1000 km the amplitude of the annually varying signal can be determined to 1 0 cm results are 30 better for a 1500 km smoothing radius and 40 worse for a 750 km radius we estimate the annually varying component of water storage for three large drainage basins the mississippi the amazon and a region draining into the bay of bengal to accuracies of 1 0 1 5 cm

an isotopic appraisal of the late jurassic greenhouse phase in the russian platform abstract oxygen and carbon isotope ratios have been determined from late jurassic callovian volgian belemnites from three locations on the russian platform gorodischi khanskaya gora and marievka all samples were examined by means of trace element geochemistry and petrography in order screen for diagenetic alteration oxygen and carbon isotopes from well preserved belemnites range from 2 24 to 0 09 and 0 57 to 1 77 respectively oxygen isotopes if interpreted in terms of temperature reveal a rise of temperatures during the oxfordian early kimmeridgian and indicate a prolonged episode of warmth during the kimmeridgian volgian the isotope data only equivocally reflect a number of significant changes in boreal tethyan ammonite assemblages a positive carbon isotope excursion is observed within the volgian but not seen within composite carbon isotope stratigraphies of the western tethys hence the jurassic may have been characterised by regional 13 c excursions related to non simultaneous organic matter deposition resulting from localised ponding semi restricted ocean circulation and a lack of tidal mixing

perturbation of the carbon cycle at the middle late jurassic transition geological and geochemical evidence a compilation of new and published stratigraphic paleontological and geochemical data is used to detect the reciprocal influences of carbon cycling and global environmental changes in the jurassic a major perturbation of the surface carbon cycling accompanied by pronounced climate and sea level fluctuations waxing and waning of continental ice affected earth history around the middle late jurassic transition mljt we establish the respective timing of changes of carbonate and organic matter sedimentation and global fluctuations of sea surface temperatures paleobiogeography and o isotope paleothermometry and sea level sequence stratigraphy so that causative mechanisms and feedback effects can be considered it is apparent that the global sea level rise and warming initiated in the late bathonian led to a constriction of carbonate platforms to low latitudes and enhanced marine organic deposition sea level and temperature optima were achieved several million years later during the middle callovian a detailed record of sea surface temperatures in the northern hemisphere based on migration of marine fauna and isotopic thermometry indicates that a drastic climatic decline set in during the early late callovian just post dating the increased capture of organic matter by marine sediments this decline in temperature is interpreted in terms of an inverse greenhouse effect triggered by drawdown of co 2 consequent upon excess carbon burial the magnitude of refrigeration and its coincidence in time with an abrupt global scale fall of sea level are both suggestive of continental ice formation at this time carbonate sedimentation was jeopardized at the mljt as a result of both global cooling and presumed p c o 2 lowering and resumed abruptly during the middle oxfordian by spreading again over mid latitude zones salient conclusions are that 1 the pattern of excess carbon burial coincident with elevated temperature but followed by climatic deterioration supports the general hypothesis that a major control on mesozoic climate was the abundance of atmospheric co 2 2 significant masses of continental ice may have formed during this part of the jurassic and correlatively high co 2 levels were certainly not sustained throughout this period 3 the global carbonate sedimentation budget correlated with the surface temperature and sea level but the latitudinal spreading of type tropical carbonates was not simply related to the thermal status of seawaters 4 on a global scale the c o r g and c i n o r g burial rates were coupled apparently through the correlation existing between the co 2 level and surface temperature

the trophic structure of the biota of the peterborough member oxford clay formation jurassic uk the peterborough member of the oxford clay formation is organic rich and contains an abundance of well preserved vertebrate and invertebrate fossils a high nutrient input supported a diverse biota phytoplankton was exceptionally abundant in the surface water and formed the basis for an intricate food web in both surface and bottom waters top predators include some of the largest known mesozoic marine reptiles a giant teleost fish was analogous to modern filter feeding whales and sharks benthic faunas depended on organic matter sinking from surface waters and two parallel food webs may have existed trophic partitioning allowed the higher level predators to become diverse especially the plesiosaurs productivity was high in the surface waters probably high in the mid water column and high on the sea floor at times although benthic diversity may have been reduced due to substrate consistency and or dysoxia bacterial activity within the sediment was also intense the contribution of organic material to the sea floor was high but heterotrophic reworking probably reduced the abundance considerably during early diagenesis a decrease in organic carbon content in the upper callovian and lower oxfordian parts of the oxford clay formation parallels a decreasing abundance of vertebrate fossils

the stable isotopic records of fossils from the peterborough member oxford clay formation jurassic uk palaeoenvironmental implications carbon and oxygen isotopic compositions of calcareous nekton aragonite kosmoceras and calcite belemnites and benthos aragonite nuculacean bivalves and calcite gryphaea from the peterborough member of the oxford clay formation vary considerably at any one horizon but show no obvious trend with time this suggests that the temperature and isotopic composition of ambient seawater may have varied considerably over short time intervals but did not change systematically during deposition of the unit thus short term fluctuations were superimposed on longer term 9stability9 in this shallow shelf environment the overlap in carbon isotopic compositions between calcareous nekton and benthos suggest a well mixed water column oxygen isotopic palaeotemperatures suggest thermal stratification provided that kosmoceras 16 28 c inhabited near surface waters and belemnites 12 19 c indistinguishable from the range for benthic bivalves were nektobenthic oxygen isotopic compositions of phosphate from both shallow and possible deeper dwelling vertebrates reptiles bony fish and sharks yield the same range of palaeotemperatures 20 29 c suggesting that all vertebrate taxa may have lived predominantly in warm shallow waters

time variations of land water storage from an inversion of 2 years of grace geoids by delivering monthly maps of the gravity field the grace project allows the determination of tiny time variations of the earth s gravity and particularly the effects of fluid mass redistributions at the surface of the earth however grace data represent vertically integrated gravity measurements thus are the sum of all mass redistributions inside the earth s system atmosphere oceans and continental water storage plus solid earth in this paper we apply a generalized least squares inverse approach previously developed by 1 g ramillien a cazenave o brunau global time variations of hydrological signals from grace satellite gravimetry geophys j int 158 2004 813 826 to estimate from the monthly grace geoids continental water storage variations and their associated uncertainties over a 2 year time span april 2002 to may 2004 tests demonstrating the robustness of the method are presented including the separation between liquid water reservoirs surface waters soil moisture groundwaters and snow pack contributions individual monthly solutions of total land water storage from grace with a spatial resolution of 660 km are presented for the 2 year time span we also derive the seasonal cycle map we further estimate water volume changes over eight large river basins in the tropics and compare with model predictions finally we attempt to estimate an average value of the evapotranspiration over each river basin using the water balance equation which links temporal change in water volume to precipitation evapotranspiration and runoff amplitudes of the grace derived evapotranspiration are regionally consistent to the predictions of global hydrological models

eustatic curve for the middle jurassic cretaceous based on russian platform and siberian stratigraphy zonal resolution we have used the stratigraphy of the central part of the russian platform and surrounding regions to construct a calibrated eustatic curve for the bajocian through the santonian the study area is centrally located in the large eurasian continental craton and was covered by shallow seas during much of the jurassic and cretaceous the geographic setting was a very low gradient ramp that was repeatedly flooded and exposed analysis of stratal geometry of the region suggests tectonic stability throughout most of mesozoic marine deposition the paleogeography of the region led to extremely low rates of sediment influx as a result accommodation potential was limited and is interpreted to have been determined primarily by eustatic variations the central part of the russian latform thus provides a useful frame of reference for the quantification of eustatic variations throughout the jurassic and cretaceous the biostratigraphy of the russian platform provides the basis for reliably determining age and eustatic events the mesozoic section of the central part of the russian platform is characterized by numerous hiatuses in this study we filled the sediment gaps left by unconformities in the central part of the russian platform with data from stratigraphic information from the more continuous stratigraphy of the neighboring subsiding regions such as northern siberia although these sections reflect subsidence the time scale of variations in subsidence rate is probably long relative to the duration of the stratigraphic gaps to be filled so the subsidence rate can be calculated and filtered from the stratigraphic data we thus have compiled a more complete eustatic curve than would be p ssible on the basis of russian platform stratigraphy alone relative sea level curves were generated by backstripping stratigraphic data from well and outcrop sections distributed throughout the central part of the russian platform for determining paleowater depth we developed a model specifically designed for this region based on paleoecology sedimentology geochemistry and paleogeography the curve describes a series of high frequency eustatic events superimposed on longer term trends many of the events identified from our study can be correlated to those found by haq et al 1988 and other sea level studies from other parts of the world but there are significant differences in the relative magnitudes of events because the eustatic curve resulting from this study is based on a stable reference frame the curve can be used in sedimentary basin modeling and as a tool for quantifying subsidence history from the stratigraphy of passive margins basins and other active regions

influence of a meteorological cycle in mid crustal seismicity of the nepal himalaya abstract the process of interseismic strain accumulation across the nepal himalaya is associated with micro seismicity also called mid crustal seismicity which occurs along the mid crustal ramp on the main himalayan thrust mht the seismicity shows strong annual periodicity in response to the annual stress variation of hydrological loads we report dominance of annual periodicity in the eastern nepal as compared to that of western nepal and overall annual periodicity dominance in the small magnitude earthquakes mw 0 3 rainfall seismicity cross correlation is significantly higher in the eastern nepal region as compared to that of western nepal with a prominent phase lag of 5 6 months with respect to the occurrence of monsoonal rainfall seasonal modulation can be explained by coulomb failure stress model and fault resonance hypothesis induced by meteorological cycle this new observation upholds the existing hypothesis that evaporation induced unloading in the himalayan foothills and adjacent indo gangetic plains during the post monsoon period i e during winter add significant component of horizontal compression to the interseismic contraction at the mht which is the main driving mechanism for the seasonal modulation

isotopic evidence for late jurassic early cretaceous climate change abstract strontium oxygen and carbon isotope ratios have been determined from late jurassic early cretaceous belemnites from the volga basin russia and kawhia harbour new zealand 87sr 86sr ratios derived from well preserved belemnites from the volga basin support a middle tithonian age derived from the analysis of the endemic ammonite fauna the kawhia harbour section records a gradual rise in 87sr 86sr values and in comparison with the published 87sr 86sr curve suggests that the lower part of the section is latest oxfordian in age whilst the upper part of the section correlates well with the biostratigraphic correlation suggestion of an early middle tithonian age although the published strontium calibration curve shows a degree of scatter our new data confirm the uniform rise in 87sr 86sr values from the late jurassic into the early cretaceous such an increase may result from either a decrease in mid oceanic ridge spreading and or an increase in weathering rates and flux of radiogenic strontium although a eustatic drop in sea level and concurrent western cordillera uplift suggests that weathering may have been the controlling factor of late jurassic seawater strontium isotope composition palaeotemperatures derived from the well preserved belemnite 18ocarb values from the volga basin indicate that the middle volgian late kimmeridgian was warm 14 20 c followed by a slight cooling and a subsequent gradual increase to the jurassic cretaceous boundary the 18ocarb values from new zealand located at a palaeolatitude of 80 s if interpreted in terms of palaeotemperature indicate a high degree of variability such variability may not be related to palaeotemperature but to changes in oceanic chemistry resulting from the formation and dissolution of an ice sheet and or snow during the oxfordian kimmeridgian carbon isotope trends for the late jurassic show a fall in values from the oxfordian with lowest values occurring in the early middle tithonian before rising but without reaching values obtained in the oxfordian the overall low 13ccarb may be related to a global increase in continental weathering and or upwelling of cooler oceanic water enriched in oxidised organic carbon 12c enriched

acceleration of greenland ice mass loss in spring 2004 in 2001 the intergovernmental panel on climate change projected the contribution to sea level rise from the greenland ice sheet to be between 0 02 and 0 09 m from 1990 to 2100 ref 1 however recent work has suggested that the ice sheet responds more quickly to climate perturbations than previously thought particularly near the coast here we use a satellite gravity survey by the gravity recovery and climate experiment grace conducted from april 2002 to april 2006 to provide an independent estimate of the contribution of greenland ice mass loss to sea level change we detect an ice mass loss of 248 36 km3 yr 1 equivalent to a global sea level rise of 0 5 0 1 mm yr 1 the rate of ice loss increased by 250 per cent between the periods april 2002 to april 2004 and may 2004 to april 2006 almost entirely due to accelerated rates of ice loss in southern greenland the rate of mass loss in north greenland was almost constant continued monitoring will be needed to identify any future changes in the rate of ice loss in greenland

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

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

application of two dimensional terrain height spectra to mesoscale modeling abstract a caution is offered with regard to the use of one dimensional terrain spectra to indicate the grid resolution needed to resolve terrain forcing in mesoscale numerical modeling exercises to illustrate this two dimensional terrain height spectra are presented for two contrasting terrains a relatively direction free topography a portion of southcentral british columbia canada and a highly ordered topography a portion of the ridge and valley terrain in pennsylvania isoamplitude plots of the two spectra show clearly the morphological differences between the two regions and indicate the degree of directionality of the ordered terrain an investigation of the wavenumber dependence of the terrain height spectra shows the spectral roll off for the first case to be essentially independent of direction and to decay roughly as wavenumber to the 5 2 power over a wavenumber range of 0 04 to 8 33 km 1 by contrast the spectral roll off in the second case is strongly dependent on direction with an ex

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

terrestrial water mass load changes from gravity recovery and climate experiment grace recent studies show that data from the gravity recovery and climate experiment grace is promising for basin to global scale water cycle research this study provides varied assessments of errors associated with grace water storage estimates thirteen monthly grace gravity solutions from august 2002 to december 2004 are examined along with synthesized grace gravity fields for the same period that incorporate simulated errors the synthetic grace fields are calculated using numerical climate models and grace internal error estimates we consider the influence of measurement noise spatial leakage error and atmospheric and ocean dealiasing aod model error as the major contributors to the error budget leakage error arises from the limited range of grace spherical harmonics not corrupted by noise aod model error is due to imperfect correction for atmosphere and ocean mass redistribution applied during grace processing four methods of forming water storage estimates from grace spherical harmonics four different basin filters are applied to both grace and synthetic data two basin filters use gaussian smoothing and the other two are dynamic basin filters which use knowledge of geographical locations where water storage variations are expected global maps of measurement noise leakage error and aod model errors are estimated for each basin filter dynamic basin filters yield the smallest errors and highest signal to noise ratio within 12 selected basins grace and synthetic data show similar amplitudes of water storage change using 53 river basins covering most of earth s land surface excluding antarctica and greenland we document how error changes with basin size latitude and shape leakage error is most affected by basin size and latitude and aod model error is most dependent on basin latitude

isotopic signals from callovian kimmeridgian middle upper jurassic belemnites and bulk organic carbon staffin bay isle of skye scotland abstract the stable isotope data presented here significantly extend and expand upon previous isotopic investigations of the middle to late jurassic interval the belemnite samples collected from the staffin bay and staffin shale formations from the isle of skye scotland yielded oxygen isotope values consistent with callovian kimmeridgian palaeotemperatures of 6 7 20 6 c the carbon isotope data comprise one of the first moderately high resolution investigations of the relationship between terrestrial 13 c org predominantly fossil wood debris and marine 13 c carb belemnites as derived from a geologically coeval record the staffin bay data reveal a broad early to mid oxfordian positive carbon isotope excursion the excursion maximum occurs in the cordatum zone british boreal ammonite zonation although high values persist into the tenuiserratum zone the correspondence between the marine and terrestrial records indicates a strong coupling of the ocean atmosphere system and suggests that the total exchangeable carbon reservoir would have been affected at this time the mid oxfordian negative carbon isotope excursions identified in published tethyan records and commonly attributed to methane release are not recorded in the staffin bay data which may suggest that the tethyan excursions do not represent fluctuations in the global carbon reservoir and that the fidelity of the methane hypothesis should be re evaluated supplementary material isotopic and geochemical data are available at http www geolsoc org uk sup18339

isotope paleontology growth and composition of extant calcareous species abstract isotope paleontology uses the isotopic composition of fossil remains of organisms to make inferences about the physical surroundings of growth of the organisms especially temperature and to obtain clues about life history and modes of growth in calcareous fossils oxygen isotopes are mainly used in the former and carbon isotopes in the latter however since physical surroundings and organism response are intimately associated both types of information are contained in each of the isotopic signals to explore the potential of isotope paleontology and to provide a basis for reconstruction a broad range of extant organisms has been studied taking the pioneering work of epstein and associates as a starting point results are summarized for a representative sampling of these studies with emphasis on work at the laboratories of the authors from the mid seventies to the present the organisms considered are nannoplankton benthic algae planktonic and benthic deep sea foraminifera larger foraminifera sponges corals bryozoans polychaetes arthropods bivalves gastropods cephalopods and vertebrates fish otoliths the survey broadly suggests that regarding oxygen isotopes materials tend to be precipitated close to equilibrium with the surrounding seawater as postulated by urey and that for carbon isotopes disequilibrium is the rule life spans growth rates differential seasonal growth and age of reproductive activity can be extracted under favorable circumstances from individual shells and skeletal parts in detail the interpretation of isotope records of individual shells is quite complicated and simple models will fail to give satisfactory results in many or most cases

variations in the earth s oblateness during the past 28 years 1 analysis of satellite laser ranging slr data indicates that the earth s dynamic oblateness j2 has undergone significant variations during the past 28 years the dominant signatures in the observed variations in j2 are 1 a secular decrease with a rate of approximately 2 75 10 11 yr 1 2 seasonal annual variations with a mean amplitude of 2 9 10 10 3 significant interannual variations with timescales of 4 6 years and 4 a variation with period of 21 years and an amplitude of 1 4 10 10 with minimum in december 1988 two large interannual variations are related to the strong el nino southern oscillation events during the periods of 1986 1991 and 1996 2002 and it appears that another interannual cycle may have started in late 2002 the superposition of the decadal variation on the interannual signal makes the j2 fluctuation appear to be anomalously large during the 1996 2002 period contemporary models of the mass redistributions in the atmosphere ocean and surface water can explain a major part of the 4 to 6 year fluctuations however the cause of the decadal variation remains unknown

organic matter from the callovian middle jurassic deposits of lithuania compositions sources and depositional environments abstract this study presents the first organic geochemical and petrographical investigation of the callovian deposits of the eastern part of the central european basin it is shown that in both the terrigenous papil formation lower callovian and shallow to deeper marine facies of the papartin and skinija formations middle and upper callovian respectively terrestrial organic matter predominates this is reflected by the carbon preference index values higher than 1 2 for all samples and in some cases higher than 2 as well as the occurrence of characteristic higher plant biomarkers like cadalene dehydroabietane simonellite and retene moreover in the case of the papil formation sugiol a natural product terpenoid produced by distinct conifer families has been detected in clay sediments the occurrence of such a biomolecule in the middle jurassic clays is reported for the first time its occurrence is probably connected with the presence of small wood debris in the clay sediments in samples of the papil formation charcoal fragments co occurring with unsubstituted polycyclic aromatic hydrocarbons were detected indicating that wildfires took place during the early callovian of lithuania and or neighbouring areas in the middle and upper marine callovian sediments of lithuania there is no evidence of anoxic conditions occurring in the water column however periodic anoxic or strongly dysoxic episodes may have occurred most probably below the photic zone during the deepest phase of the late callovian transgression as is evidenced from pyrite framboid diameter distribution and general impoverishment of benthic fauna huminite reflectance r r values for the investigated area are in the range of 0 21 0 31 suggesting the occurrence of immature organic matter such values indicate that these investigated deposits were close to the surface during their whole diagenetic history and the thickness of younger cover did not exceed ca 500 m this is also supported by a biomarker analysis in which less thermally stable hopanes and hopenes significantly dominated

reconstructing the palaeoenvironment of the middle russian sea during the middle late jurassic transition using stable isotope ratios of cephalopod shells and variations in faunal assemblages abstract oxygen and carbon isotope data of well preserved belemnite rostra and ammonite shells are presented from the callovian oxfordian boundary uppermost lamberti to lowermost cordatum zones of the dubki section near saratov in the russian platform palaeotemperatures calculated for nektobenthic belemnites averages of 5 c and 8 c for cylindroteuthids and belemnopseids respectively show the presence of cold bottom waters in the central part of the middle russian sea during the studied interval palaeotemperatures calculated for ammonites which are assumed to have lived in near surface waters are considerably higher average 13 c the presented data show a vertical thermal gradient in the middle russian sea the belemnite oxygen isotope record and the relative abundances of ammonite families in the dubki section do not correlate with each other probably as a result of different depth habitats of ammonites and belemnites a review of literature isotope data shows the climatic zonation in european seas at the middle late jurassic transition despite the flux of cold polar waters to the middle russian sea and the area of scotland there is no evidence for glaciation at the middle late jurassic transition changes in water circulation during a sea level highstand were likely a source of spreads of cold bottom waters and cardioceratid ammonite fauna in this time period the belemnite isotope record of the callovian oxfordian boundary in the russian platform is characterized by significant scatter of 13c values no temporal carbon isotope trend is observed the 13c values of russian belemnite rostra average 2 6 vpdb being 1 to 2 higher than the values of coeval lower oxfordian belemnites from the area of the submediterranean ammonite province higher than submediterranean 13c values of russian belemnite rostra are likely related to high biologic productivity and or high organic matter burial in semi isolated boreal subboreal marine basins

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

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

carbon and oxygen isotope composition of oxfordian early kimmeridgian belemnite rostra palaeoenvironmental implications for late jurassic seas abstract stable isotope analyses have been undertaken on oxfordian early kimmeridgian belemnite rostra derived from three palaeogeographic provinces of europe 1 the boreal subboreal province isle of skye in scotland 2 the submediterranean province central poland and southern germany and 3 the mediterranean province pieniny klippen belt in the western carpathians the samples have been screened for possible diagenetic alteration by using cathodoluminescence and trace element analyses and have been found to be largely well preserved calculated palaeotemperatures 10 15 c and analyses of belemnite habitats suggest that the boreal subboreal belemnites were living in a relatively shallow sea not deeper than 100 150 m while the other belemnites possibly inhabited deeper neritic environments despite the influence of a vital effect the 13c values of belemnite rostra are interpreted to reflect primary variations in the oceanic carbon isotope signal the fairly uniform submediterranean 13c values indicate a similar isotope composition of dissolved inorganic carbon dic in the area of sedimentation of sponge megafacies in the deep tethyan shelves the slightly lowered 13c values of some mediterranean belemnites might occur due to upwelling providing 12c enriched bottom waters onto the area of the czorsztyn ridge in the oxfordian the discernibly more positive 1 2 5 13c values of boreal subboreal belemnites are related to a high biologic productivity and a high organic matter burial in the partly isolated boreal sea the stated differentiation in carbonate 13c values distinctly exceeds present day differences in isotope composition of seawater dic

primary and diagenetic isotopic signals in fossils and hemipelagic carbonates the lower jurassic of northern spain stable isotope and trace element analyses of 230 jurassic pliensbachian toarcian samples from northern spain have been performed to test the use of geochemical variations in fossils belemnites and brachiopods and whole rock hemipelagic carbonates as palaeoceanographic indicators although the succession analysed reinosa area westernmost basque cantabrian basin has been subject to severe thermal alteration during burial diagenesis the samples appear to be well preserved the degree of diagenetic alteration of the samples has been assessed through the application of integrated petrographic chemical and cathodoluminescence analyses it is demonstrated that brachiopods and whole rock carbonates although widely used for palaeoceanic studies do not retain their primary marine geochemical composition after burial diagenesis in contrast there is strong evidence that belemnite rostra preserve original isotopic values despite pervasive diagenesis of the host rock well preserved belemnite shells non luminescent to slightly luminescent typically show stable isotope values of 4ae3 to 0ae7 d 13 c 0ae7 to 3ae2 d 18 o and trace element contents of 950 l gg 1 sr and sr mn ratios 80 this study suggests that the degree to which diagenesis has affected the preservation of an original isotopic composition may differ for different low mg calcite fossil shells and hemipelagic bulk carbonates behaviour that should be considered when marine isotopic signatures from other ancient carbonate rocks are investigated multiple non luminescent contemporaneous belemnite samples passed the petrographic and geochemical tests to be considered as palaeoceanic recorders yet their d 13 c and d 18 o values exhibited moderate scatter such variability is likely to be related to the palaeoecological behaviour of belemnites and or highfrequency secular variations in sea water chemistry superimposed on the longterm isotopic trend a pronounced positive carbon isotope excursion up to 4ae3 is documented in the early toarcian serpentinus biozone which correlates with the toarcian d 13 c maximum reported in other european and tethyan regions

a review of the broad pattern of jurassic sea level changes and their possible causes in the light of current knowledge abstract an assessment is made of the current state of research into jurassic sea level changes based on new insights into depositional patterns in relation to these changes and new stratigraphic information from several widely separated regions across the world the bearing of this information on alternative models respectively involving sea level rise interrupted by stillstands or falls is then evaluated the gross pattern appears to be one of more or less gradual rise of sea level through the period interrupted by episodes of comparative stillstand rather than eustatic fall and several episodes of significant regression are shown to be the result of regional tectonics major episodes of eustatic rise took place in the early hettangian early sinemurian early pliensbachian early toarcian early and late bajocian middle callovian and late oxfordian to kimmeridgian a significant episode of rapid and very extensive regression possibly global took place at the end of the triassic but other regressive episodes in the late aalenian bathonian late oxfordian kimmeridgian and tithonian are clearly only regional in extent there is no evidence for glacioeustasy and most if not all of the regional or global changes recognised can readily be related to plate tectonics the events at the triassic jurassic boundary seem to be the result of mantle plume activity centred on the central atlantic region

climatic and oceanographic isotopic signals from the carbonate rock record and their preservation stable isotopic data from marine limestones and their constituent fossils and marine cements can provide quantitative evidence for changes in global climate and ocean circulation oxygen isotopic data can indicate changes in temperature and ocean composition whereas stratigraphic variation in carbon isotope ratios may reflect changes in the carbon cycle that can be linked to changes in oceanic productivity and atmospheric greenhouse gases terrestrial carbonates meteoric cements calcretes and speleothems similarly offer significant potential for understanding the evolution of terrestrial climates by providing evidence for the composition of rainwater and the nature of vegetative cover primary environmental isotopic signals may be obscured by the effects of post depositional diagenetic alteration cementation and replacement reactions can take place in a wide range of diagenetic environments the diagenetic history of an individual limestone is determined by a combination of its mineralogical diagenetic potential and depositional setting together with subsequent changes in relative sea level and burial history carbon isotopic values are less prone to alteration during diagenesis than oxygen values but shifts can be significant where organogenic carbon is incorporated linear covariation of carbon and oxygen values is not a reliable indicator of diagenetic alteration water rock interaction and fluid mixing may produce non linear distributions attempts to determine long term changes in climatic and oceanographie conditions through isotope stratigraphy of shallow water limestones must include an assessment of the diagenetic history of the materials analysed petrographic examination using conventional microscopy backed up where appropriate by cathodoluminescence and scanning electron microscopy together with elemental and strontium isotopic analysis can help to identify the effects of diagenetic alteration where material with a range of different degrees of alteration is preserved in the same sediment it may be possible to compare patterns of isotopic and elemental variation and to attempt to unravel the effects of diagenesis in order to determine primary environmental isotopic signals recent research has shown that these techniques can be successfully employed in both phanerozoic and precambrian sediments

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

marine faunal realms of the mesozoic review and revision under the new guidelines for biogeographic classification and nomenclature consensus among the friends of paleobiogeography produced tentative guidelines to the classification and nomenclature of marine biogeographic units i e biochores based on these loose rules the present paper is a critical review of all published mesozoic marine realms subrealms and superrealms formerly called climatic belts biochores are defined by the overall endemism within geographic and time envelopes that include choro and chrono types without consideration of facies or climate the hierarchy of ranks or tiers is superrealm realm subrealm province subprovince only ranks in italics are obligatory region is informal these ranks scale with endemism geographic range and persistence in time biochores are named geographically following nomenclatural guidelines not strict rules of synonymy and homonymy with priority beginning with uhlig s paper of 1911 uhlig s two climatic belts are tentatively accepted as optional top ranking superrealms for times of exceptional global endemism available names for them are euroboreal or panboreal new and tethys panthalassa the validity of the 29 existing names for realm group biochores realms subrealms and superrealms in the marine mesozoic is discussed 19 names are rejected for a variety of reasons including synonymy homonymy and usefulness the most important realm group biochores are arctic and boreal atlantic in the boreal euroboreal realm or superrealm and tethyan mediterran caucasian indo pacific jurassic early cretaceous and austral middle late cretaceous in the tethys panthalassa superrealm

slow postseismic recovery of geoid depression formed by the 2004 sumatra andaman earthquake by mantle water diffusion 1 earthquakes are accompanied with mass redistributions and cause changes in gravity field and shape of geoid an equipotential surface coincident with the mean sea surface such coseismic changes were detected by satellite gravimetry after the 2004 sumatra andaman earthquake but little has been known on what happens on geoid after the earthquake here we report slow postseismic recovery of coseismic geoid depression from satellite measurements this cannot be explained with simple afterslip or viscous relaxation of maxwellian upper mantle it suggests the relaxation of coseismic dilatation and compression by the diffusion of supercritical h2o abundant in the upper mantle such a self healing system of coseismic geoid undulations a brand new role of water in mantle would significantly reduce the amount of permanent shifts of the earth s rotation axis by earthquakes

coseismic gravity changes of the 2011 tohoku oki earthquake from satellite gravimetry 1 the massive tohoku oki earthquake of a moment magnitude mw of 9 0 occurred on 11 march 2011 off the pacific coast of the northeastern japan the mass redistribution in and around the focal region associated with this earthquake was studied using the gravity changes detected by gravity recovery and climate experiment grace satellite after the 2004 sumatra andaman and the 2010 central chile maule earthquakes the present study presents the third case of clear detection of coseismic gravity changes by grace the observed gravity changes were dominated by decrease over the back arc region of 7 gal or less this reflects to a large extent coseismic crustal dilatation of the landward plate they agree well with the changes calculated with the green s function for the realistic earth using fault parameters inferred from coseismic crustal movements the spatial patterns of the gravity changes of these earthquakes are very similar because they are all shallow angle reverse faulting at convergent plate boundaries we found linear relationship between gravity decreases and seismic moments

anomalous precipitation signatures of the arctic oscillation in the time variable gravity field by grace summary the arctic oscillation ao controls winter climates in the northern hemisphere to a large extent positive ao brings lower higher surface temperature and higher lower precipitation in high middle latitude regions and negative ao reverses the situation in this study we investigate signals of anomalous precipitations caused by ao using the data of the gravity recovery and climate experiment grace satellites wintertime mass deviations inferred from grace in the high and middle boundary 55n latitude regions in eurasia showed highly positive and negative correlations with the ao indices this possibly reflects the northward and southward shift of the centre of winter precipitation during the positive and negative phases of ao respectively wintertime mass deviations also showed positive and negative correlations with the ao indices in the northern and southern parts of greenland respectively but the boundary was further to the north say 75n ao redistributes the water mass as much as 1000 gt between high and middle latitude regions in the northern hemisphere such mass redistribution causes significant surface deformation by loading large enough to be observed by global positioning system this also causes the shift of the earth s rotation axis especially towards the greenwich meridian large enough to be detected with space geodetic techniques ao signatures are also derived from the empirical orthogonal function eof analysis as the first leading mode of grace data after excluding seasonal linear and quadratic components the eof analysis also demonstrates that though ao is a main contributor to bring anomalous winter precipitation in the northern hemisphere as a whole in north america however influence of the el nino and southern oscillation on the winter precipitation anomaly is larger than ao

thermal evolution of tethyan surface waters during the middle late jurassic evidence from δ18o values of marine fish teeth 1 oxygen isotope compositions of phosphate from vertebrate tooth enamel were measured to determine the evolution of tropical sea surface 0 owing to limited growth of continental ice during the early middle oxfordian the resulting sea level fall is estimated to be at least 50 m and is compatible with a global regression stage the middle oxfordian thermal minimum is followed by a new warming stage of 3 4 c from the middle to the late oxfordian

stable isotope records from sepia officinalis a key to understanding the ecology of belemnites abstract the stable isotope ratios 1 8 o 1 3 c of the aragonite of cuttlebones of sepia officinalis were measured on a high resolution scale where every septum was measured our studies aim at understanding whether variations of the isotope signature are controlled by ontogenetic and or ecological factors five specimens were reared from eggs under known water temperatures a sixth specimen was caught in the german part of the north sea the data suggest that the oxygen isotope composition is in isotopic equilibrium with the surrounding seawater and reflects ambient temperature migration and seasonal temperature changes are visible in the acquired data set the carbon isotope signature shows signs of biofractionation and no direct correlation to the oxygen signature as far as ontogeny and ecology are concerned

mode of origin of dispersed clasts in jurassic shales southern part of the yana kolyma fold belt north east asia abstract in an effort to estimate climatic conditions in high latitudes we undertook field studies of middle to late jurassic clast bearing mudrocks in northeastern russia most of the enclosed clasts previously attributed to seasonal ice rafting consist of rip up shale clasts associated with turbidites and blocks and slabs of intrabasinal sediments the emplacement processes for these materials are here considered to have been gravity driven mass movements evidence of ice rafting not of the best quality but including penetration structures in adjacent shale is restricted to one locality in mudrocks of the kolyma river area which are tentatively assigned to the middle to late bathonian marked seasonality with freezing winters therefore may have characterized this time in accord with gcm results suggesting strong seasonality in the jurassic high latitudes the evolution of jurassic climate is still to be defined however as other reports of clasts in bajocian tithonian mudrocks in the region remain unevaluated

testing palaeo environmental proxies in jurassic belemnites mg ca sr ca na ca δ18o and δ13c we test the hypothesis that the noise in belemnite records through time results from changing climate we do so by comparing palaeo proxies mg ca sr ca na ca 18o 13c in two species of toarcian belemnites acrocoelites odontobelus vulgaris 14 specimens and acrocoelites acrocoelites subtenuis 10 specimens deposited in a period of time that was short relative to the timescale of climate change the specimens are interpreted to have been regurgitated from the stomach of a marine predator and so were deposited together in a geological instant of early jurassic time in a o vulgaris isotopic and elemental palaeo proxies group tightly suggesting that this belemnite occupied a restricted environmental niche in a a subtenuis elemental and isotopic compositions spread more widely suggesting that this species occupied a greater range of habitats possible sexual dimorphism in a o vulgaris is reflected in bimodal mg ca and differing intra rostral distribution of mg in putative dimorphs concentrations decline by 30 from apical line to rim in specimens with high mg ca but are largely invariant radially in specimens with lower mg ca sexual dimorphism in a a subtenuis yields a bimodality in size mg ca and intra rostral distribution of mg larger specimens have a higher mg ca and mg concentrations that increase along radial traverses from apical line to rim whilst the smaller specimens show a mid rostral minimum in mg concentration radial profiles of concentrations for sr and na vary little in all forms toarcian belemnites of these species thus show strong biofractionation effects on mg ca and little or no observable biofractionation of sr ca or na ca it follows that much of the noise in belemnite records results from biofractionation and from a cosmopolitan life style of some belemnite species rather than climate change for toarcian belemnites we suggest that sr ca is the best indicator of palaeo temperature

plate tectonic trigger of changes in pco2 and climate in the oxfordian late jurassic carbon isotope and modeling evidence abstract the transition from the middle to the late jurassic was characterized by significant changes in oceanography and climate and by changes in global carbon cycle as shown in the c isotope record a prominent mid oxfordian positive excursion in bulk carbonate carbon isotope values 13 c carb with an amplitude of more than 1 has been documented from many sections in the northern tethys realm in this study we present new bulk organic matter c isotope data 13 c org from northwestern tethys that do not record the mid oxfordian positive excursion in carbonate carbon on the contrary 13 c org decreases during the interval of the most rapid increase in 13 c carb we demonstrate that this decrease is not due to a changing marine terrestrial organic carbon partitioning but that the contrasting isotope trends record peculiar environmental and climate changes which occurred near the beginning of the late jurassic using a simple carbon cycle model we show that an increase in atmospheric p co 2 starting at modern levels could be the cause of contrasting trends in 13 c carb and 13 c org we suggest that a reorganisation of ocean currents related to the opening and or widening of the tethys atlantic pacific seaway and a massive spread of shallow sea carbonate production led to higher p co 2 model simulations indicate that this increase in p co 2 may have triggered changes in the biological carbon pump and in organic carbon burial that can explain the middle oxfordian c isotope record

elemental and oxygen isotope composition of early jurassic belemnites salinity vs temperature signals well preserved calcitic belemnite samples from the basque cantabrian basin of northern spain have been analyzed to improve our current understanding of the chemistry of seawater as an index of paleoceanographic changes during the early jurassic a period punctuated by times of oceanic anoxia and global mass extinctions because the oxygen isotope composition of calcite depends not only on temperature but also on salinity we present here a combination of sr ca mg ca and 18o analyses that helped us to evaluate both effects separately comparison between the temporal records and cross plots of these geochemical parameters shows a good correlation of mg ca with 18o and a weak correlation of sr ca with 18o comparison of our belemnite 18o record with coeval o isotope profiles from other paleogeographic domains suggests the existence despite differences in the absolute isotopic values of a major negative shift during the serpentinus zone that is regionally reproducible this event is linked to the early toarcian ocean anoxic event oae and suggests the existence of global changes in paleoclimatic and paleoceanographic conditions that are reflected largely in the geochemical composition of seawater compared to our results however other early toarcian 18o data reported from northern european basins are generally depleted 1 3 1 6 in contrast mg ca ratios display similar values these differences in 18o data suggest a salinity component for the northern european data and provide evidence for a north to south salinity gradient within the north european interior boreal seaway during the early jurassic this study suggests that the secular variation of mg ca is a useful proxy for discriminating between temperature and salinity effects on the oxygen isotope composition of fossil shells and highlights the prospect of using the mg ca ratios of belemnite calcite to calculate paleotemperatures independently of salinity the findings of our study may help to calibrate 18o curves in other basins by removing the salinity component of their 18o records which may help to calculate water density gradients between the jurassic seas of northern and southern europe

isotopic evidence for temperature variation during the early cretaceous late ryazanian mid hauterivian oxygen and carbon isotopic compositions have been determined from the belemnite genera acroteuthis and hibolites sampled from the early cretaceous ryazanian hauterivian interval of the speeton clay formation filey bay england the speeton clay formation consists of a series of claystones and calcareous mudrocks deposited in an epicontinental sea 18 o values from belemnites which met petrographic and chemical criteria for well preserved skeletal carbonate indicate warm marine palaeotemperatures c 12 15 c for much of the early valanginian whilst cool temperatures

constraining hydrological and cryospheric mass flux in southeastern alaska using space based gravity measurements 1 watersheds draining into the gulf of alaska goa experience large seasonal and inter annual variations of water in the form of rain snow and ice but accurate constraints on these variations have been difficult to obtain over larger geographic regions water variations can be inferred directly from the gravity recovery and climate experiment grace data however because goa variations occur over such a small region the inferred average value of water flux increases as the applied smoothing of the grace data decreases we use this observed scaling together with scaling results obtained from forward models to infer a seasonal amplitude of 115 20 km3 of water and an average contribution to sea level rise over the two years of data of 0 31 0 09 mm yr these results suggest that accelerated melting that began in the late 1990s as inferred from altimetry continues unabated

detailed oxygen and carbon isotope stratigraphy of the oxfordian in central poland a collection of 73 belemnites and brachiopods from detailed stratigraphically documented sections in the polish jura chain of central poland representing almost the whole oxfordian stage was studied for oxygen and carbon isotopes the 18o and 13c v pdb values range from 3 6 to 0 5 and from 1 6 to 2 for belemnite rostra and from 2 5 to 0 4 and from 1 6 to 4 3 for brachiopod shells respectively the 13c temporal trends of belemnite rostra and brachiopod shells show a constant isotopic difference ca 2 5 3 which is interpreted as a vital effect of belemnites or as a result of different life environments 18o values are similar in both groups of fossils the 18o values in the lower and middle oxfordian oscillate around 0 and decrease in the upper oxfordian this decrease results mainly from diagenetic overprint as proved by the cathodoluminescence studies the lower and middle oxfordian 18o derived temperatures were constant in consequence of significant ocean depth for this reason there are no established links with distribution of ammonite faunas the 13c temporal trend displays a gentle slope through the oxfordian and reaches maximum values at the turn of the plicatilis transversarium zones of the middle oxfordian which is commonly considered as a global event it can be related to the sea level highstand and growth crisis of carbonate platforms the decrease in 13c values starting in the upper middle oxfordian is interpreted to be due to the acceleration of carbonate sedimentation rate during this time period

oxygen and carbon isotope composition of callovian lower oxfordian middle upper jurassic belemnite rostra from central poland a record of a late callovian global sea level rise abstract oxygen and carbon isotope data of well preserved and stratigraphically well dated belemnite rostra are presented from a callovian lower oxfordian succession of the polish jura chain south central poland that was deposited in a deep shelf environment palaeotemperatures calculated from belemnite 18 o values 9 to 14 c indicate relatively constant climatic conditions during studied callovian and early oxfordian intervals belemnite 13 c temporal trends which are interpreted to record primary variation in the isotope composition of dissolved inorganic carbon reservoir display a prominent positive carbon isotope shift up to around 1 7 vpdb in the upper callovian this excursion is preceded and followed by a drop in average 13 c values of belemnite rostra of around 1 the late callovian carbonate carbon isotope excursion is likely linked to the enhanced storage of organic carbon in shelf sediments during a global sea level rise the presented data are not compatible with the theory of prolonged global glaciation at the middle late jurassic transition

facies variations across the middle upper jurassic boundary in western europe and the relationship to sea level changes abstract a facies analysis of callovian oxfordian boundary beds has been carried out on numerous sections across western europe with the aim of constructing marine bathymetric curves for each geographic area onshore outcrops in northwest and northeast scotland and borehole cores from the beatrice field in the inner moray firth basin were studied virtually all the sediments are siliciclastic and often thick an early callovian transgression is recorded from skye and northeast scotland but the influence of local tectonics limits the lateral extent of distinctive lithological units within england the callovian succession differs considerably from that found elsewhere the most interesting unit is the upper callovian hackness rock a condensed bed with chamositic ooids which is thought to signify deposition at a time of rising relative sea level the basal oxfordian contains an organic rich clay that may reflect a period of maximum flooding associated with anoxic conditions and the clays above are likely to have been deposited during the ensuing regression in central and southern england the callovian oxfordian boundary occurs within the oxford clay the change from the lower to the middle oxford clay middle upper callovian boundary marks a regional shallowing of the sea signified by higher silt and kaolinite content while the topmost callovian the lamberti limestone is condensed and marks a time of relatively high sea level with a fall in the proportion of kaolinite four regions in france were studied normandy poitou burgundy and ardeche the normandy succession is very similar to that in dorset with the stage boundary occurring at the junction of two clay formations a period of maximum flooding occurred at this boundary before initial regression in the early oxfordian resulted in a renewed terrigenous input the other regions generally have a very condensed calcareous callovian often with a pelagic character the condensed iron ooidal limestones of the spanish iberian chain were deposited in a relatively deep water offshore setting the majority of sections record a phase of severe sediment starvation during the latest callovian and earliest oxfordian zones which are likely to reflect a period of maximum flooding in the swiss jura the most significant period of negligible sedimentation rates occurred in the two zones across the stage boundary clear deepening or shallowing trends cannot readily be recognised in the offshore succession of the swabian alb the comparison of a series of bathymetric curves has led to the recognition of regional sea level events in western europe during the callovian early oxfordian interval a regional sea level rise occurred during the middle and late callovian reaching its greatest extent in the latest callovian lamberti zone and highstand conditions and incipient sea level fall characterised the early oxfordian a literature review of boundary beds in seven further regions from five continents has shown that a middle callovian sea level rise and late callovian early oxfordian phase of high sea level can be recognised on a global scale the european regional sea level changes are therefore considered to be eustatic in origin and probably related to sea floor spreading in the atlantic a eustatic curve has been constructed and compared with two other such curves it differs from that of hallam also based on the facies analysis technique but is quite similar to that of exxon workers based on sequence stratigraphic concepts

strontium isotope profile of the early toarcian jurassic oceanic anoxic event the duration of ammonite biozones and belemnite palaeotemperatures we profile 87sr 86sr 13c 18o sr ca mg ca and na ca in belemnites through pliensbachian and toarcian strata on the yorkshire coast uk which include the early jurassic oceanic anoxic event the 87sr 86sr profile shows that the relative duration of ammonite subzones differ by a factor of up to 30 the lower jurassic exaratum subzone is 30 times longer than the clevelandicum subzone because the exaratum subzone in yorkshire which contains the anoxic event is condensed by a factor of between 6 5 and 12 2 times relative to adjacent strata using our 87sr 86sr profile the resolution in correlation and dating attainable in the interval is between 1 5 m and 15 m of section and better than 0 25 myr in parts of the sequence this stratigraphic resolution equals that attainable with ammonites a new age model is provided for late pliensbachian and early toarcian time that is based on the 87sr 86sr profile through the sequence the sr ca mg ca na ca and 18o of belemnite carbonate covary suggesting that elemental ratios may be useful for palaeotemperature measurement our 13cbelemnite data splits into three the previously reported positive isotope excursion to 6 5 in the early toarcian we speculate that the excursion s resulted from addition to surface waters of isotopically heavy co2 via ebullition of methanogenic co2 from the sediment during early burial of organic rich 10 toc sediments