carbon isotopic composition nitrogen content and inclusion composition of diamonds from the roberts victor kimberlite south africa evidence for 13c depletion in the mantle the c isotopic composition and n content of a suite of diamonds of known inclusion mineral composition from the roberts victor kimberlite have been measured the mean 13c content of diamonds containing peridotitic minerals x 5 4 vs pdb s 0 9 n 65 does not differ significantly from those containing sulfides x 4 9 s 0 9 n 20 diamonds containing eclogitic minerals can be subdivided into two groups based on their carbon isotopic composition group a x 15 5 s 0 4 n 10 and group b x 5 6 s 0 6 n 4 the clinopyroxenes occluded by the group a diamonds are depleted in sio2 mgo and cao and significantly enriched in al2o3 feo and mno compared to clinopyroxenes occluded by group b diamonds carbon in two graphite diamond eclogites has a mean isotopic composition of 5 31 in both samples graphite shows a slight enrichment in 13c compared to the coexisting diamond the range of n concentrations of diamonds containing peridotitic or eclogitic minerals is essentially the same 0 to 750 ppm while it is considerably larger for sulfide containing diamonds 0 to 1700 ppm there is no difference in the c isotopic composition between type i and type ii diamonds for sulfide and peridotitic minerals occluding diamonds all type ii diamonds containing eclogitic minerals belong to group a no correlation between n content and c isotopic composition could be established although a large range in both variables is observed for the sample suite the composition of eclogitic minerals included in diamonds of low 13c content differs from that of eclogite xenoliths characterized by 18o depletions which have been related to subduction processes hence the data available do not suggest a common cause for the depletion of the heavy isotopes of the two elements the chemical and isotopic characteristics of the suite of diamond samples reflect different mantle environments diamonds depleted in 13c 13c 15 to 16 come from a region at greater depth than those of 13c contents of 5 to 6 the source region of the former is characterized by higher fe mn al and lower mg ca si and n contents than that of the latter

subducting oceanic crust the source of deep diamonds inclusions of majoritic garnet in diamonds from the jagersfontein kimberlite formed at unusually great depths of 250 to 500 km in the asthenosphere and transition zone the original host rocks were derived from a much shallower basaltic eclogitic source the presence of negative eu anomalies in all majoritic garnets requires a crustal origin thereby linking these very deep diamond sources to subducting oceanic crust the carbon isotope values 13c of the host diamonds fall within a narrow range at 20 which is fundamentally different from the broad range 24 to 2 and bimodal distribution of carbon isotopes of jagersfontein diamonds that formed in the shallower lithosphere this indicates that majoritic garnet bearing diamonds at jagersfontein inherited their light carbon isotopic composition directly from organic matter contained in a subducting slab these diamonds were likely formed by direct conversion from graphite well within the diamond stability field

bone and enamel diagenesis from the crystal to the environment a tribute to jean francois saliege a universite de lyon france cnrs france ecole normale superieure de lyon site monod 15 parvis rene descartes bp7000 lyon f 69342 france universite claude bernard lyon 1 43 bd du 11 novembre 1918 f 69622 villeurbanne cedex france b museum national d histoire naturelle cnrs departement ecologie et gestion de la biodiversite usm 303 umr 7209 du cnrs archeozoologie archeobotanique societes pratiques et environnements case postale 56 55 rue buffon f 75231 paris cedex 05 france

bone diagenesis in the european holocene ii taphonomic and environmental considerations we have applied cluster analysis to mercury intrusion porosimetry data from 219 archaeological bones 121 human and 98 animal and soil chemistry data from 219 accompanying soil samples 1 per bone sample to investigate the influence of soil chemistry on bone preservation the samples chosen for the study were obtained from sites ranging in time from the pre modern to the mesolithic and were representative of burial environments across europe from the baltic to the mediterranean these results represent the single largest database for archaeological bone preservation in the european holocene to date and demonstrate the potential for large scale diagenetic studies to help develop long term preservation strategies for our european heritage despite the variety of sites and environments bones could be categorised into only four main diagenetic types furthermore soil chemistry appears to significantly affect only one type of preservation the pathway characterised by loss of mineral in neutral to basic soils taphonomy and in particular the differences between the treatment of human and animal remains becomes the dominating factor in determining preservation using these results strategies for heritage management of archaeological sites can be suggested grouping sites into those requiring immediate excavation and those where in situ preservation is viable

carbon dioxide speciation in silicate melts a restart abstract using infrared spectroscopy we investigated the speciation of carbon dioxide in albitic and synthetic iron free dacitic glasses after annealing the glasses below the glass transition temperature in the temperature range 673 973 k at 0 5 gpa samples were rapidly quenched under constant pressure the experiments show that the ratio of the integrated intensities of the 2350 cm 1 band due to molecular co 2 to that of the band doublet at 1700 1375 cm 1 due to co 3 2 increases with higher annealing temperatures for both glass compositions our study demonstrates that in contrast to recent suggestions the equilibrium of the co 2 species reaction co 2 o 2 co 3 2 in silicate glasses melts shifts towards molecular co 2 with increasing temperature the co 2 species concentrations and an ideal solution model were used to determine equilibrium constants for the homogeneous species reaction we derived preliminary values for the enthalpy h 0 and entropy s 0 of this reaction assuming that the species concentrations reflect those at experimental temperatures h 0 12 2 kj mol 1 and s 0 23 3 j mol 1 k 1 for albitic composition h 0 29 2 kj mol 1 and s 0 32 3 j mol 1 k 1 for dacitic composition

latter day origin of diamonds of eclogitic paragenesis syngenetic mineral inclusions in diamonds provide the best means of determining their origin among such inclusions the peridotitic paragenesis of olivine orthopyroxene and chrome pyrope garnet is on average far more abundant than the eclogitic paragenesis of pyrope almandine garnet and omphacitic clinopyroxene1 3 diamonds of peridotitic paragenesis from the 100 myr old kimberley and finsch kimberlites in southern africa were previously shown to have originated in 150 200 km thick lithosphere beneath the kaapvaal craton 3 300 myr ago4 5 at a few localities such as the premier kimberlite in southern africa and the argyle lamproite in northwestern australia diamonds of eclogitic paragenesis predominate6 8 allowing recovery of sufficient material for complementary analysis the results of which are reported here eclogitic garnet and clinopyroxene inclusions in premier and argyle diamonds yield sm nd isochron ages of 1 150 and 1 580 myr respectively compared with host diatreme emplacement ages9 10 of 1 100 1 200 myr eclogitic inclusion ages and precursor isotopic signatures indicate a second genetically distinct origin of diamonds apparently related in time and space to kimberlite or lamproite magmatism

use of micro computed tomography imaging and porosity measurements as indicators of collagen preservation in archaeological bone abstract collagen isolated from archaeological bone is a common material for radiocarbon dating stable isotope analysis and zooarchaeology by mass spectrometry zooms however not all bones contain extant collagen leading to unnecessary destruction of unproductive bones and wasted laboratory time and resources an aim of this research is to study bone diagenesis particularly collagen destruction in an effort to develop a minimally destructive method for identifying bones with high collagen content in a multi method study of variably preserved bones from etton cambridgeshire uk we examined material properties of neolithic cattle and sheep bones including porosity surface area and elemental composition micro computed tomography microct is an imaging technique that furnishes three dimensional images of mineralized materials such as bone cortical bone porosity the percentage of total bone volume consisting of empty space as calculated using microct can act as a proxy for bone collagen preservation in general bones with high cortical porosity are unlikely to contain sufficient collagen for further analysis bones with apparently low cortical porosity have a more varied range of collagen preservation bone samples with low porosity and no extant collagen often contain micropores with a diameter of 10 nm or less that cannot be seen in microct images but are apparent in pore size distributions measured by mercury porosimetry and indicated by high surface areas measured by nitrogen adsorption furthermore a re evaluation of light induced breakdown spectroscopy data from this same assemblage confirms that ratios of calcium to fluorine may likewise indicate the state of diagenesis

a nonhydrostatic mesoscale simulation of the 10 11 june 1994 coastally trapped wind reversal abstract during the summer months the california coast is under the influence of persistent northwesterly flow several times each summer this regime is disrupted by coastally trapped wind reversals ctwr in which the northwesterly flow is replaced by southerlies in a narrow zone along the coast controversy exists as to the physical mechanisms responsible for initiation and maintenance of ctwrs while it is clear that coastal terrain is important in creating the trapped response the precise role played by terrain is unclear in the present study these issues are investigated using a nonhydrostatic mesoscale model to simulate the 10 11 june 1994 ctwr event the results show that the model successfully reproduces many of the observed features of this event including anomalous vertical structure involving the relatively shallow boundary layer with a warm nearly neutral layer above the northward propagation of southerly flow in advance of a tongue of coastal stratus fog and a substantial reduction i

stable carbon and oxygen isotope analysis of fossil tooth enamel using laser ablation abstract a technique is described whereby the 13c and 18o values of fossil tooth enamel can be measured in situ using laser ablation techniques the laser heats the sample and forms co2 from structural carbonate apatite the 18o values obtained with this method are equal to those of the phosphate oxygen due to the high temperature of reaction during ablation analytical precision is approximately 0 5 for both 13c and 18o the spatial resolution is 200 m or less which may be reduced as the technical modifications are made this method allows the analysis of samples that previously could not be analyzed due to difficulty with sample preparation size or rare nature the apparent oxygen isotope fractionation between the carbonate and laser derived oxygen co3 laser is 1 0071 for biogenic apatite at 38 c determined using the in situ laser comparison of 18o co3 and 18o laser analyses with 18o laser and 18o po4 results suggest a fractionation factor co3 po4 of 1 0083 variations in the 18o and 13c values of single teeth can be easily determined with the in situ technique this will allow the study of changes in diets or water sources during the period of tooth growth which for larger mammals can be several years for the tooth row the 13c and 18o values are important in paleodiet and paleoecology studies they can be used to study resource partitioning within an ecosystem and can shed light on the life history strategies within living and extinct species

observations and analysis of the 10 11 june 1994 coastally trapped disturbance abstract a coastally trapped disturbance ctd characterized by southerly flow at the surface on 10 11 june 1994 was observed from the california bight to bodega bay during a field experiment along the california coast north south approximates the coast parallel direction data from a special observational network of wind profilers radio acoustic sounding systems special surface data balloon ascents and a research aircraft were used with satellite and synoptic data to explore both the ctd structure and the regional scale changes before the event the disruption of the climatological northerly flow along the central california coast which preconditioned the area for the development of a ctd began with the eastward movement of a surface high into washington and oregon and the amplification of a thermal low in northern california as with most ctds in the region this occurred over the 2 3 days preceding the ctd s initiation these large scale changes caused westward advection of warm continental

an observational and numerical study of an orographically trapped wind reversal along the west coast of the united states abstract observational analyses and a high resolution simulation using the pennsylvania state university ncar mesoscale model version 5 mm5 were used to describe the coastally trapped wind reversal of 19 21 july 1994 major findings include the following the event was initiated and controlled by changes in the synoptic scale flow and particularly by the development of offshore flow over the coastal terrain of oregon although synoptic control was dominant blocking of the inversion capped marine layer and mesoscale coastal pressure ridging were important components of the event the synoptic evolution associated with the trapped reversal was characterized by a shift from climatological near zonal 500 mb flow to high amplitude upper level ridging over the eastern pacific as this upper ridge moved northeastward the 850 mb flow over oregon became northeasterly and then southeasterly and 850 mb heights fell over western oregon the combination of falling heights aloft and increasing low level offshore

raman spectroscopy of fossil bioapatite a proxy for diagenetic alteration of the oxygen isotope composition abstract fossil bioapatite may yield biogeochemical signals of paleoenvironments captured by living organisms bioapatite may be diagenetically altered however with ions added or removed post mortem such change is typically assessed using destructive and demanding techniques here raman spectroscopy is used as a rapid and non destructive way to identify significant diagenetic alteration of fossil bioapatite we found spectral parameters of phosphate symmetric stretching 1 po43 to be very sensitive to variations in apatite chemistry particularly with respect to common diagenetic components co32 f sr2 the raman spectral parameters were subsequently applied to a set of modern biogenic and geologic magmatic apatite samples as potential endmembers for diagenetic alteration raman spectra were also collected from enamel and dentin respectively resistant vs alteration prone of fossil teeth phosphate oxygen isotopic values from the same enamel dentin samples were used as an index of alteration and provided definition of raman spectral parameters as relates to diagenetic alteration diagenetically altered samples were characterised by spectra with 1 po43 widths at half maximum height less than 13 0 cm 1 and 1 po43 band positions greater than 964 7 cm 1 raman spectroscopy is shown to have potential as a tool for pre screening fossil apatite samples before further analyses

evidence of fluid inclusions in metamorphic microdiamonds from the kokchetav massif northern kazakhstan abstract microdiamonds from garnet clinopyroxenites of the kokchetav massif northern kazakhstan and associated alluvial diamonds have been investigated using infrared spectroscopy all diamonds have high nitrogen contents from 747 up to 4488 20 at ppm and are of type ib iaa nitrogen data are consistent with a diamond formation over a narrow temperature range microdiamonds from garnet clinopyroxenites are characterized by water and carbonate inclusions similar to those ocurring in fibrous coated diamonds from kimberlite which suggest that diamonds grew from a c h o fluid in contrast alluvial microdiamonds do not contain any carbonate inclusions and h2o is absent or present in only minor amounts alluvial diamonds are considerably more n rich but have a similar range of nitrogen aggregation states it is suggested that alluvial diamonds belong to a separate diamond population compared with the microdiamonds from garnet clinopyroxenites the kokchetav microdiamonds are distinct from kimberlitic fibrous diamonds in that they contain abundant ib centres have high nitrogen contents and show different populations depending on host rock type these characteristics support a metamorphic origin for the microdiamonds from the uhpm rocks of the kokchetav massif

the structure and variability of the marine atmosphere around the santa barbara channel the santa barbara channel is a region characterized by coupled interaction between the lower level atmosphere the underlying ocean and the elevated topography of the coastline the nature of these interactions and the resulting weather patterns vary between summer and winter during summer synoptic winds are largely controlled by the combined effect of the north pacific anticyclone and the thermal low located over the southwestern united states resulting in persistent northwesterly winds a well defined marine atmospheric boundary layer mabl with properties distinct from the free atmosphere above is a conspicuous feature during the summer the wind has different characteristics in each of three zones maximum winds occur in the area extending south and east from pt conception zone 1 where they initially increase as they turn to follow the coast then decrease farther east winds are usually weak in zone 2 located in the easternmost part of the channel offshore from the oxnard plain winds are also weak in zone 3 sometimes reversing to easterly at night in a narrow band located along the mainland coast summer air temperature at the surface follows the sst closely and varies significantly with location summer sea level pressure gradients are large with the lowest pressure occurring on the northeast end of the santa barbara channel diurnal variations are strongest in summer although the modulation is weakest in zone 1 the diurnal variation is parallel to the coast in all of zone 3 but the oxnard plain where it is perpendicular to the coast the height of the marine layer varies between 300 m in late afternoon and 350 m in late morning in winter synoptic conditions are driven by traveling cyclones and sometimes accompanied by fronts these are usually preceded by strong southeast winds and followed by strong northwest winds atmospheric parameters are distributed more uniformly than in summer and diurnal variations are greatly reduced sea level air temperature and pressure are more spatially uniform than in the summer spatial variations in the observed fields in the summer are consistent with a hydraulic model of the mabl as a transcritical expansion fan the summertime situation is governed by a coupled interaction between the atmosphere and the underlying water the ocean influences the density of the mabl to the extent that it behaves distinctly from the free atmosphere above resulting in strong winds polarized in the direction parallel to the coast in turn these winds provoke an upwelling response in the coastal ocean which in part determines the surface properties of the water

radiocarbon dating of biological apatites a review abstract since the early trials in the 50 s the reliability of 14c dates obtained from bioapatites has always been questioned however methodological attempts at dating biological apatites are rare the compilation of the radiocarbon dates published in radiocarbon over the period 1959 2009 shows that less than 6 of all the bone dates were performed on purified bioapatite crucial for the validation of the approach is the design of tests for the preservation of the geochemical signal in biological apatites that are relevant for 14c dating because carbonate in apatite can exchange isotopically with dissolved carbon present in the environmental fluids pretreatments are necessary but not sufficient and preservation criteria based on mineral integrity are of limited help in this case only an indirect approach based on the dating of different bone tooth fractions of the same individual and or associated material is able to distinguish between preserved and altered fossils in case of alteration it is unlikely that the rate of isotopic exchange recrystallization will be identical in skeletal tissues with different physico chemical properties and any intra individual difference measured in 14c age must result from differential diagenesis we applied this strategy to more than 100 holocene and late pleistocene localities worldwide this approach confirms that carbonate in calcined bone is very resistant to post burial isotopic exchange and is the most reliable source of inorganic carbon for 14c dating regardless of the environmental conditions large intra individual differences in 14c age are found in several european and american localities showing that both bone and enamel apatite can suffer from rejuvenation due to isotopic exchange during fossilization on the contrary the absence of significant intra individual differences in 14c age in most of the localities from arid environments africa arabic peninsula attests to the good preservation of bone apatite in these regions this contrasting situation confirms that bone diagenesis must be treated on a site by site basis and demonstrates that bioapatite is a reliable material to date skeletal remains in arid environments

evaluating the impact of acetic acid chemical pre treatment on old and cremated bone with the perio spot technique and perios endos profiles abstract the impacts of diagenesis on archaeological and palaeontological bone complicate investigations of in vivo chemical and isotopic characteristics such bone is often pre treated in an attempt to remove diagenetic alteration prior to trace element or isotopic analyses although very few standardized approaches exist for evaluating pre treatment effectiveness in this pilot study we characterize the diagenetic alteration and assess the impact of acetic acid chemical pre treatment on the trace element and structural characteristics of four bones from belgium including an early medieval cremated bone from broechem and three representative old bones of different ages ca 40 130 ka from the late pleistocene sedimentary sequence of scladina cave each bone was analyzed before and after acetic acid pre treatment using the perio spot technique and perios endos profiles we measured trace element concentrations with laser ablation inductively coupled plasma mass spectrometry la icp ms and micro x ray fluorescence spectroscopy xrf structural characteristics were investigated with raman spectroscopy and fourier transform infrared spectroscopy ftir our results indicate that chemical pre treatment had little to no significant impact on the trace element content of the early medieval cremated bone had the most impact on the youngest bone from scladina cave and had less impact on the trace element content of two older bones from scladina cave this suggests that the effectiveness of acetic acid chemical pre treatment is greater for bones undergoing early diagenetic processes has minimal impact on highly crystalline cremated bone and may preferentially leach in vivo signatures from bones undergoing later diagenesis the weights of leachates removed from each bone also correspond well with their hypothetical diagenetic states indicating that researchers could potentially assess the diagenetic state of bones by weighing the leachates produced during acetic acid pre treatment therefore our new approach may provide a valuable step toward effectively and consistently differentiating among in and ex vivo trace element signatures and by proxy those of their isotopes in archaeological and palaeontological bone

restrictions on fluorine depth profiling for exposure age dating in archaeological bones archaeological fragments of bone and teeth that are exposed to a humid environment take up fluorine from the surrounding soil the fluorine ion replaces the hydroxyl group in the mineral phase of the bone forming chemically more stable fluorapatite in cortical parts of the long bone diaphysis a fluorine concentration profile can be observed which decreases from the outer surface and the marrow cavity towards the inner parts of the bone matrix geological time spans are needed for this process to reach equilibrium and for the distribution to become uniform as the shape of the profile which can be described by a diffusion model contains information on the exposure duration of the fossil object several attempts to use fluorine profiling as a dating method have been undertaken the distribution of fluorine in an archaeological sample however is strongly influenced by environmentally induced processes of bone diagenesis i e alteration in the structure and composition of the mineral phase and degradation of organic components that may make the time information indistinct the primary chemical composition of bones can thus be obscured by diagenesis within tens hundreds or thousands of years this depends more on the diagenetic environment than on the geological age to observe the impact of environmental influence on the profile shape samples from several burial sites featuring various soil conditions have been analyzed for their fluorine distribution and preservation state this paper provides an overview on the restrictions that have to be considered when attempts are undertaken to relate a fluorine diffusion pattern to the archaeological age of a bone specimen

mantle fluid evolution a tale of one diamond abstract microinclusions analyzed in a coated diamond from the diavik mine in canada comprise peridotitic minerals and fluids the fluids span a wide compositional range between a carbonatitic melt and brine the diamond is concentrically zoned the brine microinclusions reside in an inner growth zone and their endmember composition is k19na25ca5mg8fe3ba2si4cl32 mol the carbonatitic melt is found in an outer layer and its endmember composition is k11na21ca11mg26fe7ba2si10al3p2cl5 the transition in inclusion chemistry is accompanied by a change in the carbon isotopic composition of the diamond from 8 5 in the inner zone to 12 1 in the outer zone we suggest that this transition reflects mixing between already evolved brine and a freshly introduced carbonatitic melt of different isotopic composition the compositional range found in diamond on dvk 294 is the widest ever recorded in a single diamond it closes the gap between brine found in cloudy octahedral diamonds from south africa and carbonatitic melt analyzed in cubic diamonds from zaire and botswana thus all microinclusions analyzed to date fall along two arrays connecting the carbonatitic melt composition to either a hydrous silicic endmember or to a brine endmember this connection suggests that many diamonds are formed from fluids derived form a mantle source not significantly influenced by local heterogeneities

local variations of carbon isotope composition in diamonds from sao luis brazil evidence for heterogenous carbon reservoir in sublithospheric mantle abstract taking advantage of the common occurrence of superdeep mineral inclusion assemblages we examined core to rim primary zonation in 69 diamonds from the alluvial deposits of the sao luis river juina brazil syngenetic inclusions were represented by phases of superdeep paragenesis the dominant inclusions are majoritic garnets ferropericlases and casi and casiti perovskites rare inclusions of mgsi perovskites olivines clinopyroxenes tapp phases of sio2 kyanites alsi phases kfsp k hollandite cf nal grossular merwinite native iron fe sulphides magnesite and caco3 camgsi2o6 composite inclusions were also found the diamonds from sao luis display wide variations in carbon isotopic compositions 13c from 2 7 to 25 3 the diamonds with inclusions of ferropericlase have a very narrow range of 13c values from 2 1 to 7 7 which are close to the normal mantle values in many cases diamonds with inclusions of calcic majoritic garnet and casi and casiti perovskites display marked differences from this range low 13c values 10 to 25 were observed exclusively in a series of diamonds with majorite garnets ca silicates aluminous silicates and sio2 the 13c values from the cores to rims in certain individual crystals varied substantially indicating multiple stages of growth the highly negative 13c values in the cores 20 to 25 potentially represent organic matter in metasediments of altered oceanic crust and the lower 13c values may represent mixing trends towards normal mantle compositions in this study we also found a set of diamonds that display an opposite trend of change of the carbon source from primordial mantle to subducted crust either biotic or abiotic carbon

heterogeneous rare earth element ree patterns and concentrations in a fossil bone implications for the use of ree in vertebrate taphonomy and fossilization history abstract a bone fragment cgdq 3 of falcarius utahensis a therizinosaur from the early cretaceous cedar mountain formation utah contained within a carbonate nodule was analyzed by laser ablation inductively coupled plasma mass spectrometry la icp ms in order to investigate ree variability within a thin walled phalanx previous studies have found depth related ree pattern variations however in cgdq 3 variation occurs along the circumference of the bone nasc normalized ree patterns and concentrations vary between two apparent end members a light ree enriched lree pattern similar to solution icp ms analysis of this bone characterizes approximately two thirds of the bone fragment total ree concentrations are high and do not vary significantly from the periosteal surface to the medullar surface conversely the remaining one third of the bone has ree patterns that are mree depleted and low in total ree concentrations ree concentrations in this part of the bone do not vary significantly from the periosteal to the medullar surface a positive ce anomaly is found throughout the entire bone and is greatest within the lree enriched portion of the bone this in combination with the lree enrichment suggests that the bone fossilized under reducing conditions the distance between the lree enriched and mree depleted regions is less than 1 mm isotopic and petrographic analyses of the bone and surrounding carbonate matrix suggest the ree patterns in the bone were the result of partial fossilization incomplete filling of micro pore spaces around bone crystallites in an environment with changing redox conditions the lower mree depleted part of the bone fossilized contemporaneously with a pendant cement that formed on the underside of the bone in the vadose zone formation of the pendant cement restricted water flow through the bone isolating the lower portion which incorporated a mree depleted pattern the upper part of the bone lree enriched side fossilized under more reducing conditions than the lower part this resulted in reductive dissolution of minerals such as hydrous ferric oxides and manganese oxides which were lree enriched with positive ce anomalies these ree were then incorporated into the upper part of the bone this likely occurred after the bone entered the saturated zone below the water table the thinness of the bone and presence of a pendant cement helped facilitate partial fossilization of the bone preserving the ree signature of an earlier fluid as demonstrated by this case study differences in ree patterns within a fossil may record changes in geochemical conditions during fossilization particularly when bones are encased in a material that reduces fluid permeability such as micritic vadose calcite analysis of such bones may offer the opportunity to decipher complex fluid histories that occur during fossilization la icp ms should be utilized to confirm solution icp ms analysis if it yields high ree variability prior to an interpretation of reworking or time averaging

sensitivity of coastally trapped disturbance dynamics to barrier height and topographic variability in a numerical model abstract the sensitivity of a coastally trapped disturbance ctd to topographic height is examined using simulations of the 15 18 may 1985 ctd these simulations include three with uniform topography in which the north american west coast mountains are represented by a three piece uniform ramp at the coast leading to a constant plateau inland and three with realistic topography in each trio of uniform and realistic topography simulations there is a control case in which the terrain height closely approximates reality and two variations in which the topography is multiplied everywhere by a topographic multiplication factor tmf of 1 5 and 0 5 to assess the sensitivity of the simulation to the barrier height average propagation speeds increased decreased by 15 20 with the increased decreased tmf it was found that the position of the ctd leading edge generally followed close behind a leading pressure trough minimum which propagated northward along the coast in a manner similar to a topographi

transcritical flows in the coastal marine atmospheric boundary layer abstract numerical solutions of shallow water flow in a variable width channel are computed to model the summertime marine atmospheric boundary layer off the u s west coast using an idealization of the coastline in the vicinity of point arena california as an example several steady state base flows are presented that are hydraulically transcritical these flows are strongly nonlinear weakly rotational and are forced by constant pressure gradients and damped by nonlinear bottom drag at the sea surface the transcritical base flows are supercritical in the vicinity of bends in the coastline but are subcritical to the north upstream and to the south downstream where the coastline is straight within the supercritical region orographic bends in the coastline produce expansion fans and compression jumps the same structures found in globally supercritical flows when the imposed pressure gradient forcing is increased the resulting base flow has a supercritical to subcritical transitional jump that

screening in situ bone and teeth preservation by atr ftir mapping abstract bones and teeth are highly hierarchically structured and hererogeneous materials and post mortem processes can reinforce this heterogeneity it is therefore important to consider this heterogeneity to better understand diagenetic processes in this study atr ftir mapping was applied to several heated and un heated archaeological samples and to similar modern references in order to test the potential of this method atr ftir mapping can provide spatially resolved information on alteration state of mineral and organic matter this technique allowed to describe the spatial distribution of organic and mineral matter preservation in unheated palaeolithic bones bize tournal france characterized by a better preservation in the centre of the cortical bone spatial variations in the chemical composition of an archaeological heated bone abri pataud france compared to a modern reference suggested taphonomical uptake of carbonate in the most external part this pattern could correspond to a process of re carbonatation of the calcined mineral matter in the outermost part of the sample due to combustion in a co2 rich atmosphere ftir atr is a powerful tool that allows for identifying and characterizing local heterogeneities in bone preservation this technique open new prospects to reconstruct the taphonomical history of ancient samples

grotte chauvet ardeche france a natural experiment for bone diagenesis in karstic context abstract this paper assesses the preservation of bones exposed on the floor of chauvet cave these bones are mainly from cave bears they exhibit very variable macroscopic preservation from apparently pristine specimens to those that are decomposing or coated with calcite this site offers a unique opportunity to investigate on a large scale bone diagenesis in a karstic context despite the highest priority put on the preservation of the cave features about one hundred bone fragments from most sectors of the cave could be collected for biogeochemical investigation carbon and nitrogen elemental content were measured and x ray diffraction spectra were established only about one quarter of the specimens yielded collagen that retained its biogenic isotopic signatures bones exhibiting different stages of preservation were not randomly scattered in the cave local environmental conditions seem to have led to different diagenetic pathways widely differing states of preservation were seen in bones of similar age this site provides a good case study of diagenetic process occurring in karstic sites and may be used to better understand diagenesis in less well studied caves

dynamics of a simulated north american monsoon gulf surge event abstractgulf surges are transient disturbances that propagate along the gulf of california goc from south to north transporting cool moist air toward the deserts of northwest mexico and the southwest united states during the north american monsoon they have been shown to modulate precipitation and have been linked to severe weather and flooding in northern mexico and the southwest united states the general features and progression of surge events are well documented but their detailed dynamical evolution is still unclear in this study a convection permitting simulation is performed over the core monsoon region for the 12 14 july 2004 gulf surge event and the dynamics of the simulated surge are examined initially convection associated with the tropical easterly wave precursor to tropical cyclone blas creates a disturbance in the southern goc on early 12 july this disturbance is a precursor to the gulf surge on 13 july and is a kelvin shock internal bore under the influence of rotation that diss

isotope fractionation related to kimberlite magmatism and diamond formation abstract this paper deals with a model of carbon isotope fractionation presumed to accompany the movement of mantle fluids in the first part of the article the experimental data and the relationships revealed are generalized and discussed the remainder of the paper describes the model the isotope compositions of different forms of carbon related to kimberlite magmatism vary widely in diamonds 13c values range from 34 5 to 2 8 carbonate bearing autholiths in kimberlites occur enriched in 13c up to 35 organic matter including that occurring in fluid inclusions of magmatic minerals of kimberlites is depleted in 13c down to 30 it is concluded that the 13c distribution for diamonds is specific for a particular occurrence different kimberlite pipes different regions etc principal differences in isotopic distribution patterns for diamonds of ultrabasic and basic paragenesis exist isotopically light diamonds are related only to the latter when a diamond consists of several sequential generations of growth coated diamonds diamond in diamond 13c values of the early generation vary widely whereas the isotopic composition of the latter is more uniform the intention of the model is to explain the observed variations of carbon isotope composition of diamond and other carbonaceous substances related to kimberlite magmatism the model is based on the interaction of reduced sub asthenospheric fluid with the relatively oxidized lithosphere it is suggested that diamonds of ultrabasic paragenesis lherzolite and harzburgite mineral assemblages are produced during interaction of the fluid with sheared garnet lherzolite which is considered to be primitive mantle rock during contact with the more oxidized mantle reduced carbon ch4 may partially be converted to co2 isotope exchange in co2 ch4 system combined with rayleigh distillation may provide a significant isotope fractionation diamonds of the basic eclogitic paragenesis are considered to be related to this fractionated carbon also occurrence of carbonate material highly enriched in 13c is explained by the model

constraining the internal variability of the stable isotopes of carbon and nitrogen within mantle diamonds the carbon and nitrogen isotope values of mantle xenoliths and xenocrysts are used to trace the cycling of volatiles in the deep earth for example to place empirical constraints on the origin of diamond forming carbon in the mantle the global database for diamond shows that the 13c value of peridotitic diamonds is very narrow typically around 5 whereas eclogitic diamonds can show positive and very negative 13c values resembling crustal carbonates and crustal organic carbon 2 commonly interpreted to reflect a relationship between eclogitic diamond formation and subduction zone planet tectonics curiously diamonds from both parageneses can show positive crust like and negative mantle like 15n values from 20 most of these data are derived from single stage combustion gas sourced mass spectrometry which produces simplistic datasets by fragmenting single diamonds or using in situ ion beam techniques it is known that single diamonds can show large scale heterogeneity for their carbon isotope values and nitrogen abundances sometimes as large as entire populations of diamond across a few hundred micrometres what is less well known is the scale of nitrogen isotope heterogeneity within single diamonds and if the nitrogen isotope heterogeneity of single diamonds can provide an insight into why diamonds that show very restricted 13c values show a much large range of 15n values to investigate the scale and to determine the origin of the nitrogen isotope heterogeneity source vs fractionation during diamond formation shown for populations of mantle diamonds we have determined multiple 13c 15n values and nitrogen abundances from 14 monocrystalline mcds and 25 polycrystalline diamonds pcds using step wise oxidation gas sourced mass spectrometry these data show that the heterogeneity shown for carbon and nitrogen isotope values from single diamond samples presented here is typically 5 and 8 respectively both of which are comparable to the standard deviation for the mean mantle 13c and 15n values 3 and 4 however there are samples that show much larger heterogeneities for 13c and 15n values 23 and 33 respectively which cannot be generated by equilibrium stable isotope fractionation during or prior to diamond formation these data suggest that isotopic heterogeneity may be present within the diamond forming fluid on sub mm scale or that these diamonds formed during multiple diamond formation events from isotopically distinct sources from these 39 samples there are only 5 pcds that show a larger range of carbon isotopes relative to nitrogen isotopes but of these 5 samples only 2 show a range of 13c values outside of analytical uncertainty the remaining 34 samples show a greater isotopic heterogeneity for 15n relative to 13c values the samples with the largest carbon and nitrogen isotopic heterogeneity are also the samples with low bulk 13c values 10 whilst there is no relationship between the ranges of nitrogen isotope values for a given sample and the corresponding bulk 15n value or nitrogen content these data show that 15n values recorded in mantle diamonds are relatively heterogeneous and can show both mantle like negative and crustal sedimentary like positive 15n values within the same sample we conclude that the large range of nitrogen isotope values seen within individual diamonds means that the observation of negative mantle like nitrogen in mantle diamonds acquired by single stage bulk combustion isotope ratio mass spectrometry cannot be used as a conclusive indicator for a mantle origin for the entirety of the diamond forming carbon and vice versa also the behaviour of 15n 14n is not coupled with the behaviour of 14n 12c during diamond formation instead it appears that diamond forming fluids can have positive and negative 15n values irrespective of their 13c value s these data suggest that subduction induced nitrogen isotope heterogeneity may not be coupled with subduction induced carbon isotope heterogeneity in diamond forming fluids

the dynamics of coastally trapped mesoscale ridges in the lower atmosphere abstract the dynamics of coastally trapped ridges that propagate in the marine layers of western north america and southeastern australia is examined a nonlinear semigeostrophic theory shows that the coastal ridges develop initially as an alongshore intrusion of denser marine air that is driven by the synoptic scale pressure gradient nonlinear kelvin waves evolve with the intruding flow on a slower time scale governed by the dynamic parameters if dispersive effects balance the nonlinearities then these waves evolve into solitary form otherwise the nonlinear waves steepen so that the leading edge of the ridge eventually propagates as a shock the theory is applied to two ridging events in california and one in southeastern australia in each case good agreement is found between theory and observations of the evolution times and propagation speeds of the coastal ridges the theory also explains the observed behavior of the events at prominent convex bends and gaps in the coastal topography

dynamic mechanisms of the gulf surge 1 the gulf surge is a summertime phenomenon associated with the north american monsoon that transports moisture from the gulf of california into western portions of the united states this phenomenon has been acknowledged operationally and by researchers for over 30 years the surge is typically linked to the presence of some sort of low pressure system such as an easterly wave mesoscale convective system or hurricane located near the southern end of the gulf of california proposed mechanisms for the gulf surge are gravity currents ageostrophic flows kelvin or rossby edge waves the purpose of this paper is to describe the fundamental dynamics of each of these mechanisms and assess their plausibility through scale analyses and idealized numerical simulations and to suggest signatures that may appear in data and output of more sophisticated numerical models

regular cuboid diamonds from placers on the northeastern siberian platform abstract alluvial placers of the northeastern siberian platform are characterized by a specific diamond population regular cuboids forming a continuous color series from yellowish green to yellow and dark orange this is the first comprehensive study of a large number of cuboid diamonds focusing on their morphology n content and aggregation state photoluminescence c isotopic composition and inclusions the cuboids are cubic i e nearly flat faced to subrounded crystals most of them are resorbed the cathodolominescence images and the birefringence patterns show that many cuboid diamonds record deformation the cuboid diamonds are characterized by unusual ftir spectra with the presence of c single nitrogen atom and a pair of neighbour nitrogen atoms centers and two centers of unknown origin termed x and y the presence of single substitutional nitrogen defects c centers in all cuboid diamonds testifies either storage in the mantle at relatively cool conditions or formation just prior to eruption of their host kimberlites the studied diamonds are also characterized by the presence of specific set of luminescence centers n3 h3 s1 nv o and nv some of which are suggested to have formed during deformation subsequent to diamond growth the cuboid diamonds show a wide range of carbon isotope compositions from mantle like values towards strongly 13 c depleted compositions 6 1 to 20 2 13 c combined with the finding of an eclogitic sulfide inclusion the light carbon isotope compositions link the formation of the studied cuboids to deeply subducted basic protoliths i e former oceanic crust

fluid and mineral inclusions in cloudy diamonds from koffiefontein south africa silicates carbonates and brine were detected in microinclusions in cloudy diamonds from koffiefontein the silicates belong to either the eclogitic or the peridotitic paragenesis they are similar in composition to the larger mineral inclusions found in other koffiefontein diamonds and record similar pressures and temperatures of formation 1000 1200 c 4 6 gpa the clouds also carry additional mineral phases that were not detected before in koffiefontein phlogopite high si mica an al mg rich phase and carbonates in many cases silicate minerals coexist together with brine in individual microinclusions brines associated with either eclogitic or peridotitic minerals have similar composition and both are rich in water cl k and carbonates izraeli et al 2001 the above findings together with the high proportion of cloudy diamonds in koffiefontein suggest that brine penetration into neighboring peridotitic and eclogitic rocks was pervasive the high carbon content of the brine as dissolved carbonates initiated diamond growth in both rock types most on preexisting diamonds that now form inclusion free cores the low aggregation state of nitrogen in the cloudy diamonds relative to other diamonds from koffiefontein indicates either a somewhat lower temperature of storage in the mantle which may be the reason for the presence of brine rather than melt or a young event of cloudy diamond formation

analysis of the 13 14 july gulf surge event during the 2004 north american monsoon experiment abstract gulf surges are disturbances that move northward along the gulf of california goc frequently advecting cool moist air from the goc or eastern tropical pacific ocean into the deserts of the southwest united states and northwest mexico during the north american monsoon nam little attention has been given to the dynamics of these disturbances because of the lack of reliable high resolution data across the nam region high temporal and spatial observations collected during the 2004 north american monsoon experiment are used to investigate the structure and dynamical mechanisms of a significant gulf surge on 13 14 july 2004 integrated sounding systems deployed along the east coast of the goc and an enhanced network of rawinsonde sites across the nam region are used in this study observations show that the 13 14 july gulf surge occurred in two primary stages the first stage was preceded by anomalous low level warming along the northern goc on 13 july sharp cooling moistening and increased

experimental study on diamond dissolution in kimberlitic and lamproitic melts at 1300 1420 c and 1 gpa with controlled oxygen partial pressure to evaluate the dissolution processes of diamond crystals in kimberlitic and lamproitic magmas a series of diamond dissolution experiments were carried out in the graphite stability field at 1300 1420 c and 1 gpa under the wi mw and hm buffers dissolution agents used include an aphanitic kimberlite from wesselton mine south africa and a lamproite from mount north west kimberley australia with increasing run duration diamond morphology changed from a sharp octahedron through combinations of octahedron and tetrahexahedroidal forms to spherical tetrahexahedroid having rounded faces negatively oriented trigons were formed on the octahedral 111 face as the degree of diamond dissolution increased the trigons changed from smaller shallow types to larger deep types the dissolution rate in the kimberlitic solvent at 1300 c was 0 12 mm h under the hm buffer 0 0034 mm h under the mw buffer and 0 0017 mm h under the wi buffer whereas that at 1420 c was 0 014 mm h under the wi buffer in the lamproitic solvent the dissolution rate was 0 0024 mm h at 1420 c under the wi buffer the data indicate that diamond dissolves in silicate melts as carbonate ions through an oxidizing reaction the degree of dissolution strongly depends on temperature oxidation state and the compositional dependence of co 2 solubility in the melts

associated chemical and carbon isotopic composition variations in diamonds from finsch and premier kimberlite south africa abstract the carbon isotopic composition of 66 inclusion containing diamonds from the premier kimberlite south africa 93 inclusion containing diamonds and four diamonds of two diamond bearing peridotite xenoliths from the finsch kimberlite south africa was measured the data suggest a relationship between the carbon isotopic composition of the diamonds and the chemical composition of the associated silicates for both kimberlites similar trends are noted for diamonds containing peridotite suite inclusions p type and for diamonds containing eclogite suite inclusions e type higher 13c p type diamonds tend to have inclusions lower in sio2 ol al2o3 opx gt cr2o3 mgo mg mg fe ol opx gt and higher in feo ol opx gt and cao gt higher 13c e type diamonds tend to have inclusions lower in sio2 al2o3 gt cpx mgo mg mg fe gt na2o k2o tio2 cpx and higher in cao ca ca mg gt cpx consideration of a number of different models that have been proposed for the genesis of kimberlites their xenoliths and diamonds shows that they are all consistent with the conclusion that in the mantle regions exist that are characterized by different mean carbon isotopic compositions

numerical modeling of a coastal trapped disturbance part ii structure and dynamics abstract a detailed analysis of a simulation of a coastal trapped disturbance ctd using the colorado state university regional atmospheric modeling system rams is presented the ctd considered 15 18 may 1985 represents an example of a strong mesoscale trapped event with abrupt gravity current like transitions in many meteorological parameters and which was closely tied to the synoptic forcing propagation of this event along the west coast of north america occurred from initiation in the southern california bight baja california coastal region to the northern tip of vancouver island and the event appeared to have no difficulty in negotiating significant bends or gaps in the coastal mountains unlike some other events that have ceased or stalled near cape mendocino point arena and the mouth of the columbia river it is found that warm offshore flow ahead of the ctd and cool onshore flow in the southern california bight northern baja california coastal region both driven by the westward tracking

a numerical study of a southeast australian coastal ridging event abstract a numerical study of the 9 11 november 1982 southeast australian coastal ridging event is presented the mesoscale coastal features of this event have been previously described as a coastally trapped disturbance ctd however the analysis presented in this paper shows that the model coastal trapping is of secondary importance in generating the coastal ridging given the potential controversy particular emphasis in this paper is placed on identifying the causes of the ridging the paper follows a previous study by the authors in which a colorado state university regional atmospheric modeling system simulation of this event was validated in this event contributions to ridging along the southeastern australian coast came from both synoptic and mesoscale phenomena in the model a southern ocean anticyclone that tracked east from the great australian bight toward the southern tasman sea led to a large scale steady pressure increase over the entire southeast australian region ridging at the victo

measurements and relationships of diagenetic alteration of bone from three archaeological sites four diagenetic parameters have been chosen to represent the state of diagenesis of bone buried on archaeological sites they are histological preservation protein content crystallinity and porosity how these parameters are measured is described and results from populations of bones from three different sites are presented the results show the extent and variation in the degree of change both within a site and between sites in particular the correlations between diagenetic parameters are examined which give clues about the processes which cause alteration the value of porosity determinations both at the intercrystalline level and at coarser levels in revealing the degree of diagenetic change in bone and in underlying the dynamics of the interaction between buried bone and the surrounding water is stressed the data also indicate but are too restricted to prove the following microbiological attack is generally complete within less than 500 years substantial levels of protein may remain in bone after maximal micromorphological alteration loss of protein appears to be independent of other diagenetic change the correlated lose of microporosity with increase of crystallinity suggests these changes may arise from the dissolution perhaps with subsequent recrystallization of the smallest hydroxyapatite crystallites

thermodynamics and lattice vibrations of minerals 5 applications to phase equilibria isotopic fractionation and high pressure thermodynamic properties in previous papers in this series a model that uses available elastic structural and spectroscopic data on minerals has been used to predict the thermodynamic functions cv heat capacity s entropy e internal energy and f helmholtz free energy in this paper four applications to problems of current geochemical and geophysical interest are presented 1 interpretation of complex trends of calorimetric data 2 calculation of phase equilibria 3 calculation of oxygen isotopic fractionation factors and 4 estimation of the effect of pressure on thermodynamic functions the model demonstrates that trends in high temperature thermodynamic properties of silicates are determined by the position and relative numbers of high frequency modes generally antisymmetric si al o stretching modes the position of these modes varies systematically with degree of polymerization of tetrahedra and therefore high temperature calorimetric behavior is relatively systematic as a function of crystal structure and mineral composition trends at low frequency are much more complex because the low frequency optic modes that most strongly influence the low temperature thermodynamic functions depend in a complex way on the size coordination and mass of cations and various polyhedra in the minerals the heat capacity curves of kyanite andalusite and sillimanite and of quartz coesite and stishovite show crossovers that cannot be explained by debye theory which accounts only for acoustic mode behavior but can be explained by the model spectra proposed because proper account is taken of the changing low and high frequency optic modes upon polymorphic transformations the proposed model is sufficiently accurate that phase equilibrium problems can be addressed the quartz coesite stishovite equilibrium curves the kyanite andalusite sillimanite triple point and the breakdown of albite to jadeite plus quartz are cited as specific examples for each example predicted slopes of equilibrium curves agree moderately well to excellently with slopes determined experimentally the calculated slopes are sensitive to spectroscopic parameters particularly to the distribution of optic modes in the far infrared this sensitivity is discussed in detail for the albite breakdown reaction the model can be used for prediction of isotopic fractionation factors if spectra of the isotopic forms of the mineral are known or postulated a simple set of rules for generating hypothetical spectra of 18o minerals from measured spectra of the 16o forms is given reduced partition functions are calculated for 13 minerals at 298 k the model values of reduced partition function 1000 ln of these minerals decrease in the order quartz calcite albite muscovite clinoenstatite anorthite diopside pyrope grossular zircon forsterite andradite rutile in good agreement with experimental data at 1000 k the first six minerals show small crossovers so that the order becomes calcite muscovite albite quartz anorthite and clinoenstatite the differences in 1000 ln at high temperature for these minerals are so small that the model probably cannot address the deviations from experimental trends the model clearly defines the region in which the fractionation factors do not follow a 1 t trend and should be useful for extrapolation of experimental data to low temperatures finally a modified gruneisen parameter model is proposed for shift of the lattice vibrational frequencies under compression and thermodynamic properties to 1000 kbar 1000 k are given for nine minerals at 1 mbar the predicted decrease in entropy at 298 k ranges from 54 of the 1 bar value for periclase to 25 for stishovite

why do crystallinity values fail to predict the extent of diagenetic alteration of bone mineral spectroscopic indicators of bone crystallinity such as the infrared splitting factor irsf are commonly used to determine the general state of preservation of ancient bone in principle such indices might be expected to act as a proxy for alteration of bone mineral and thus could be used to screen bones or portions of bones for likely preservation of in vivo biogenic trace element and stable isotope signals we tested the relationship between irsf and bone mineral composition in two suites of well characterised recent and pleistocene bones initially crystallinity change and trace element uptake are correlated apparently both controlled by decomposition of the organic phase and exposure of bone crystal surfaces this relationship breaks down in older bones where authigenic phosphate growth and mineral pore water interactions are no longer rate limited by the breakdown of collagen and exposure of crystal surfaces in these conditions the extent of chemical alteration of bone will be controlled by site specific conditions and thus while ftir spectra of bone provide a broad indication of organic content and apatite recrystallisation they are not reliable proxies for the degree of diagenetic alteration in terms of biogenic geochemical signals

crystallization of diamond from a silicate melt of kimberlite composition in high pressure and high temperature experiments in high pressure and high temperature experiments 1800 2200 c and 7 0 7 7 gpa diamond crystallized and grew in a volatile rich silicate melt of kimberlite composition this diamond has well developed 111 faces and its morphologic characteristics resemble those of natural diamond but differ from those of synthetic diamond grown from metallic solvent catalysts the kimberlite melt has a strong solvent catalytic effect on diamond formation supporting the view that some natural diamonds crystallized from volatile rich melts in the upper mantle

chemical heterogeneity in carbonado an enigmatic polycrystalline diamond abstract carbonado a polycrystalline variety of diamond is characterized by unusual carbon isotope compositions with bulk 13c values clustered tightly between 23 and 30 relative to pdb these values are significantly lighter than harzburgitic diamond with a range in 13c from 1 to 10 and fall near the lower extreme for eclogitic diamond ranging from 3 to 34 in combination with textural and inclusion data these isotopic compositions have led scientists to question whether carbonado originated in the mantle or in the crust previous studies of carbonado have revealed a bimodal grain size distribution that correlates with cathodoluminescence cl emissions we believe that these textures result from a two step growth process and we have obtained additional chemical evidence that supports the identification of two distinct crystal populations ion microprobe analyses of a central african carbonado reveal a bimodal distribution of 13c values of 24 and 26 with an instrumental precision of 0 29 secondary ion mass spectrometry analyses also demonstrate that this 13c distribution coincides with variations in nitrogen abundance and both of these chemical zonations correlate with cl emission signatures a one dimensional analysis of self diffusion of carbon in diamond suggests that isotopic homogenization occurs extremely slowly even under upper mantle conditions whereas the microscale distribution of carbon isotopes in carbonado does not constrain the temperature pressure or time of carbonado formation it does provide a geochemical signature that recorded the dynamics of the growth process

carbon isotope fractionation during experimental crystallisation of diamond from carbonate fluid at mantle conditions we report first results of a systematic study of carbon isotope fractionation in a carbonate fluid system under mantle pt conditions the system models a diamond forming alkaline carbonate fluid using pure sodium oxalate na2c2o4 as the starting material which decomposes to carbonate co2 and elementary carbon graphite and diamond involving a single source of carbon following the reaction 2na2c2o4 2na2co3 co2 c near liquidus behaviour of carbonate was observed at 1300 c and 6 3 gpa the experimentally determined isotope fractionation between the components of the system in the temperature range from 1300 to 1700 c at 6 3 and 7 5 gpa fit the theoretical expectations well carbon isotope fractionation associated with diamond crystallisation from the carbonate fluid at 7 5 gpa decreases with an increase in temperature from 2 7 to 1 6 this trend corresponds to the function carbonate fluid diamond 7 38 106 t 2

states of preservation of bones from prehistoric sites in the near east a survey abstract a survey of the states of preservation of organic material in 30 fossil bones from 16 different prehistoric sites in the near east shows that whereas almost all the bones have little or no collagen preserved they do with few exceptions contain non collagenous proteins these macromolecules therefore represent an important reservoir of indigenous fossil bone constituents

a model investigation of the dynamics of a coastally trapped disturbance abstract numerical simulations of the 15 17 may 1985 coastally trapped disturbance ctd event along the west coast of north america are compared with the schematic model of ctd evolution developed by skamarock rotonno and klemp srk which was based upon more idealized simulations it is shown that the general evolution of the simulated may 1985 ctd is consistent with the srk schematic model it is further shown that secondary effects not contained in the srk simulations such as diurnal radiation variations and mesoscale topographic variations can account for the variable ctd initiation and propagation observed both in nature and in the present numerical simulations diurnal radiation variations coupled with differential heating of land and ocean appear to play an important role in setting up the alongshore temperature gradient necessary for ctd formation and evolution the modeled ctd is found to change dynamical characteristics from an initial kelvin wave bore similar to that discussed by ralph

3he4he ratio noble gas abundance and k ar dating of diamonds an attempt to search for the records of early terrestrial history the 3he4he ratios measured in 27 southern africa diamond stones four from premier mine and the rest of unidentified origin range from 4 2 10 8 to 3 2 10 4 with three stones above 1 10 4 we conclude that the initial helium isotopic ratio 3he4he 0 in the earth was significantly higher than that of the planetary helium a 3he4he 1 42 10 4 but close to the solar helium 3he4he 4 10 4 the apparent k ar ages for the twelve diamonds of unidentified origin show enormously old age indicating excess argon 40 3he4he evolution in diamonds suggests that the diamonds with the high 3he4he ratio 2 10 4 may be as old as the earth noble gas elemental abundance in the diamonds relative to the air noble gas abundance shows monotonie decrease with a decreasing mass number this paper discusses the implications of these observations on the early solar system and the origin of diamonds

microdiamonds frontier of ultrahigh pressure metamorphism a review abstract this is a comprehensive review paper devoted to microdiamonds from ultrahigh pressure metamorphic uhpm terranes incorporated in orogenic belts formed at convergent plate boundaries in paleozoic mesozoic alpine time when in 1980 the first small diamonds were discovered within amphibolite granulate facies metamorphic rocks it came as a great surprise that buoyant continental crust could be subducted to depths of hundreds of kilometers and then subsequently exhumed since then much progress has been made in understanding the mechanism of these diamonds formation and the number of new diamond bearing uhpm terranes was significantly increased especially within european orogenes moreover new variations in tectonic settings in which uhp rocks can be formed and exhumed came to the attention of geologists simply due to the finding of diamonds in places previously forbidden for their formation e g oceanic islands ophiolites and forearc environments over the past decade the rapidly moving technological advancement has made it possible to examine microdiamonds in detail and to learn that part of them has a polycrystalline nature that they contain nanometric multiphase inclusions of crystalline and fluid phases and that they keep a crustal signature of carbon isotopes scanning and transmission electron microscopy focused ion beam techniques synchrotron infrared spectroscopy micro x ray diffraction and nano secondary ion mass spectrometry studies of these diamonds provide evidence that they keep traces of fluid originated from both crustal and mantle reservoirs and that they probably interacted with deep mantle plumes hypotheses proposed for diamond formation in subduction zones founded on both analytical and experimental studies are discussed the paper also emphasizes that the discovery of these microdiamonds as well as coesite triggered a major revision in the understanding of deep subduction processes leading to a clear realization of how continental materials can be recycled into the earth s mantle and geochemically rejuvenate it

directional chemical variations in diamonds showing octahedral following cuboid growth a progression from cuboid to octahedral growth has been observed in 16 natural diamonds from yakutian kimberlites x ray and cathodoluminescence topography have revealed that the change in morphology of diamonds with cloudy cuboid cores may occur without mixed habit growth but via generation of numerous octahedral apices on cuboid surfaces and subsequent gradual transformation into regular octahedral morphology nitrogen aggregation in both cuboid and octahedral domains of such diamonds suggests that they have had a long residence time under mantle conditions micro inclusions in the cuboid domains of the diamonds testify to the nucleation and growth of cuboid cores from a hydrous carbonatitic oxidized fluid the transition from cuboid hummocky growth rich in inclusions to octahedral growth without inclusions may be linked to decreasing supersaturation in the parent fluid measurements of 13c and nppm by ion microprobe show that the chemical variations observed between inner cuboid domains and outer octahedral zones commonly have a systematic character and as such they are probably not due to purely kinetic effects the peripheral octahedral zones are always enriched in 13c in comparison with inner cuboid ones and the total nitrogen content decreases with the change from cuboid to octahedral growth the octahedral outer zones show a gradual progressive increase in 13c with an overall change of up to 5 from the cuboid core 13c usually between 8 and 6 to the diamond margin 13c usually between 4 and 2 decreases in 13c of this magnitude with a gradual increase in 13c may be attributed to the rayleigh fractionation operating on a single parent fluid of close to normal mantle 13c composition with diamond precipitating by the reduction of carbonatitic fluid in a closed system however one sample shows a variation of 13c of approximately 17 to 6 and therefore suggests a possible change of fluid source composition from one containing subducted crustal organic carbon to one with common mantle carbon

models of coastally trapped disturbances during the spring and summer the climatological northerly flow along the u s west coast is occasionally interrupted by transitions to southerly flow that have a limited offshore scale and appear to be manifestations of marine layer flow that is rotationally trapped by the coastal mountains existing climatological and observational studies suggest that a synoptic scale offshore flow initiates these coastally trapped disturbances ctds using idealized simulations produced with a 3d nonhydrostatic model the authors find that an imposed offshore flow will produce ctds in idealized coastal environments the imposed flow first weakens the prevailing northerly flow in the marine layer and lowers the pressure at the coast the marine layer flow around this low pressure evolves toward geostrophic balance but is retarded as it encounters the coastal mountains to the south of the low and subsequently deepens the marine layer in this region the elevated marine layer then begins progressing northward as a kelvin wave and later may steepen into a bore or gravity current this progression being the ctd many observed features accompanying ctds are found in the numerical simulations including the formation of a mesoscale pressure trough offshore and deep southerlies in the ctd at the coast stability in the atmosphere above the marine layer can give rise to topographically trapped rossby waves and stronger ctd winds in these stable conditions propagation of wave energy away from the disturbance does not preclude strong quasi steady propagating ctds

equilibrium oxygen hydrogen and carbon isotope fractionation factors applicable to geologic systems as demonstrated by the chapters in this short course stable isotope techniques are an important tool in almost every branch of the earth sciences central to many of these applications is a quantitative understanding of equilibrium isotope partitioning between substances indeed it was harold urey s 1947 thermodynamically based estimate of the temperature dependence of 18o 16o fractionation between calcium carbonate and water and a recognition of how this information might be used to determine the temperatures of ancient oceans that launched the science of stable isotope geochemistry the approach pioneered by urey has since been used to estimate temperatures for a wide range of geological processes e g emiliani 1955 anderson et al 1971 clayton 1986 valley this volume in addition to their geothermometric applications equilibrium fractionation data are also important in the study of fluid rock interactions including those associated with diagenetic hydrothermal and metamorphic processes baumgartner and valley this volume shanks this volume finally a knowledge of equilibrium fractionation is a necessary first step in evaluating isotopic disequilibrium a widespread phenomenon that is increasingly being used to study temporal relationships in geological systems cole and chakraborty this volume in the fifty four years since the publication of urey s paper equilibrium fractionation data have been reported for many minerals and fluids of geological interest these data were derived from 1 theoretical calculations following the methods developed by urey 1947 and bigeleisen and mayer 1947 2 direct laboratory experiments 3 semi empirical bond strength models and 4 measurement of fractionations in natural samples each of these methods has its advantages and disadvantages however the availability of a variety of methods for calibrating fractionation factors has led to a plethora of calibrations not all of which are in agreement in this chapter we evaluate the major methods for determining fractionation factors

crystalline inclusions and c isotope ratios in diamonds from the snap lake king lake kimberlite dyke system evidence of ultradeep and enriched lithospheric mantle abstract u type paragenesis inclusions predominate 94 7 among the crystalline inclusion suite of 115 diamonds 4 2 mm obtained from the recently discovered snap lake king lake skl kimberlite dyke system southern slave canada the most common inclusions are olivine 90 and enstatite 22 sulfide cr pyrope chromite and cr diopside inclusion are less abundant 15 10 5 and 1 respectively results of the inclusion composition study demonstrate the following a the relatively enriched character of the mantle parent rocks of the u type diamonds the average mg of olivine inclusions is 92 1 and of enstatite inclusions average 93 3 cao content in cr pyrope inclusions is relatively high 3 73 5 75 wt b four of ten u type cr rich pyrope inclusions contain a majoritic component up to 16 8 mol which requires pressures of 110 kbar carbon isotopes compositions for 34 diamonds with u type inclusions have a 13c range from 3 2 to 9 with a strong peak around 3 5 this is much heavier than the ratios of u type diamonds from siberia and south africa 4 5 diamonds with olivine inclusions can be divided into two groups based on their 13c values as well as the mg and ni fe ratio in the olivines most show a narrow range of 13c values from 3 2 to 4 8 average 3 72 and have olivine inclusions with mg less than 92 3 and relatively high fe ni ratios a second group is characterized by a much wider variation of c isotope composition 13c varies from 3 8 to 9 0 average 5 97 and the olivine inclusions having a higher mg up to 93 6 and relatively low fe ni ratios this difference in the c isotope composition may have several explanations a peculiarities of asthenosphere degassing coupled with an abnormal thickness of lithosphere b the abnormal thickness and enriched character of lithospheric mantle c involvement of subducted c of crustal origin in the processes of the diamond formation the presence of subcalcic cr rich majorite up to 17 mol pyropes of low ca harzburgite paragenesis among the crystalline inclusion suite of skl diamonds is strong evidence for the existence of diamondiferous depleted peridotite in lithospheric mantle at depth near 300 km beneath southern slave area and is postulated to be one of the main reasons for the much heavier c isotope composition of skl u type diamonds in comparison with those from siberian and south african kimberlites

modelling the growth of natural diamonds abstract in the following article we have reviewed the mineralogical chemical physical and isotopic evidence concerning the growth of coated diamonds and have combined it to produce a comprehensive model for their formation we suggest that the coatings formed during a period of metasomatic activity which preceded the eruption of their host kimberlites ultrapotassic co21bh2o rich fluids resulted from the crystallisation of diamond free kimberlitic magmas intruded into the deep lithosphere the kimberlite magmas were derived from an asthenospheric source which was globally quite uniform in terms of the isotopic composition of carbon and nitrogen 13c and 15n both being close to 5 the fluids produced during crystallisation invaded overlying diamondiferous lithosphere in which different regions could contain diamond populations with different mineralogical isotopic and physical characteristics depending on the history of their source region either intrinsic to their formation or due to reaction with reduced lithosphere the fluids were super saturated with carbon although not to such an extent as to allow for the nucleation of new diamonds when these super saturated fluids encountered older diamonds new and fibrous diamond growth commenced immediately this period of metasomatic activity was followed rapidly by one or more successful kimberlite eruptions which transported the now coated diamonds to the surface in the crust carbonates within hypabyssal facies kimberlites will have 13c values which reflect the deep seated source 5 whereas those within diatreme facies may be more variable due to outgassing of co2 during eruption finally we consider isotope fractionation related to growth we suggest that approaches based on equilibrium are not appropriate to diamonds but rather that it is better to consider the nature and kinetics of the surface reactions leading to growth where diamond growth is very rapid as may be the case for fibrous diamond we propose that there will be no difference in isotopic composition between the fluid and diamond and not the 3 4 13c depletion in the latter predicted by theoretical treatments octahedral diamonds are more problematic since far less is known about their growth conditions however we show in principle how the content and perhaps isotopic composition of nitrogen within a diamond may be controlled by its growth rate we are uncertain whether 13 c would be affected

in situ oxygen isotope micro analysis of faunal material and human teeth using a shrimp ii a new tool for palaeo ecology and archaeology a sensitive high resolution ion microprobe shrimp ii has been used to make high spatial resolution in situ micro analyses of oxygen isotopes in fish otoliths and teeth from fossil herbivores and a neanderthal large intra tooth variations in the oxygen isotopic composition up to 9 were observed in the enamel of herbivores from the neanderthal fossil site of payre consistent with preservation of seasonal cyclicity the range of isotopic compositions observed in neanderthal tooth enamel was much smaller w3 possibly the result of a longer enamel maturation time averaging out variability an archaeological otolith from a preceramic site in northern peru exhibited marked changes in d 18 o over life due either to the fish occasionally migrating from the sea to a lower salinity habitat or to short lived rises in sea water temperature a fish otolith from australia s willandra lakes world heritage area showed clear seasonal variations but also a general trend towards isotopically heavier and more saline water as indicated by higher d 18 o and sr ca values resulting from increased evaporation the results of these case studies are compared to results of oxygen isotope analysis using more conventional methods and demonstrate the ability of the shrimp ii to provide precise high spatial resolution in situ oxygen isotope analyses of a variety of biogenic materials this approach has major advantages over conventional methods it can provide rapid micro scale isotopic analyses of sub permil precision without the need for chemical preparation of the sample

cathodoluminescence tools provide clues to depositional history in miocene and pliocene mammalian teeth abstract this paper presents the results of a study which used cathodoluminescence cl observations optical images and sem spectra as a tool for assessing diagenetic processes during fossilisation of continental mammalian teeth the study was performed on fossil teeth of large mammals gomphotheriidae rhinocerotidae and hippopotamidae from namibia and from kenya with ages from the lower and middle miocene to pliocene the fossil sites are distinguished by their environmental conditions they include floodplain deposits fluvial deposits of the proto orange river and aeolianite deposits in namibia and fluvio lacustrine deposits of different ages in kenya optical cl provides information about the sites environments and diagenetic processes related to those environments a blue intrinsic luminescence for the aeolianite deposits and purple to yellowish for floodplain or fluvial deposits the cl spectra of these samples show sharp emission bands which are classically related to late recent incorporation of rare earth elements ree substituting in the ca 2 sites high resolution mapping of the distribution of these ree shows a gradient from the enamel interior low concentrations to the outer enamel margin high concentrations

growth of diamond in hydrous silicate melts this study demonstrates that a hydrous halide bearing silicate melt is a viable medium for diamond growth experiments were conducted in the mgo sio2 h2o c kcl nacl system which was used as a model for harzburgitic mantle in no case did we observe crystals that could be interpreted as spontaneously nucleated but growth of diamond on seed crystals at 1 400 1 600 c and 7 gpa in experiments of 4 h duration was observed the addition of kcl to the system produced crystallization of diamond at temperatures as low as 1 400 c at higher temperatures larger growth features were produced than those that seen in the kcl free system at the same conditions the nacl bearing system is different in these experiments the diamond seed crystals show evidence of possible dissolution and layer growth albeit more subdued growth than in the kcl system therefore nacl may be an inhibitor of diamond growth in a hydrous silicate melt based on these results hydrous silicate melts could play a role in formation of diamond in either deep subduction zones or above slabs imbricated against a lithospheric root in the sub continental lithospheric mantle the water and halide necessary for their formation could be transported into the mantle in hydrous phases such as serpentine in subducting lithospheric slabs dehydration of serpentine at 200 km depth would release hydrous halide bearing fluids into the overlying mantle wedge or lithospheric root triggering melting at conditions similar to those of the formation of natural diamond

a preliminary study of 15n14n in octahedral growth form diamonds abstract the 13 c 15 n and nitrogen concentrations have been determined in 43 octahedral diamonds from southern africa australia and north america the sample set included locations such as finsch south africa a mine which produces diamonds having 13c values close to 5 and argyle australia a mine which produces 13c depleted diamonds the nitrogen within high 13c diamonds 13 c 6 4 to 2 9 was generally depleted in 15n relative to atmospheric nitrogen 15n 12 3 to 5 9 mode 4 similar to the results which have been obtained previously from fibrous diamond it is believed that the volatiles from which these diamonds grew are primitive being derived from a source located beneath the continental lithosphere which may have changed little in terms of 13c and 15n since the mid archean the low 13c diamonds 13c 19 4 to 9 5 contained nitrogen generally enriched in 15n relative to air 15n 3 0 to 16 4 mode 5 it is suggested that the major carbon isotope heterogeneity within the mantle as represented by diamonds such as these is located in deep mechanically unstable regions of the continental lithosphere the isotopic compositions of both c and n are consistent with this heterogeneity resulting from the subduction of crustal material however isotope fractionation related directly to diamond growth cannot be ruled out

nanocrystalline diamond from the earth s mantle underneath hawaii abstract melt inclusions in a mantle derived garnet pyroxenite xenolith from salt lake crater hawaiian island of oahu have been analysed by means of transmission electron microscopy including energy dispersive x ray analysis electron energy loss spectroscopy and electron diffraction the melt inclusions represent trapped low degree melt that metasomatised the hawaiian mantle lithosphere before the eruption of the host magma the inclusions consist of a c cl s rich glass of basaltic composition an exsolved gas fluid phase mainly co2 with minor amounts of co h2o and some unidentified c h and h s species and or carbonate diamond is the major phase in the glass ranging in size between a few and several hundred nanometres two varieties of nanocrystalline diamonds are identified polycrystalline aggregates of nanometre size diamonds are tentatively explained as pseudomorphs after carbonate while single crystals are suggested to have crystallised from the melt other nanocrystalline phases include native fe and cu fes fes2 zns ags and several ti nb zr ir in pd rich phases of unknown composition overall the observed mineral assemblage suggests that the melt was highly reduced and strongly enriched in volatiles and trace elements of contrasting geochemical affinity our findings are the first evidence for a metasomatic impregnation of the hawaiian mantle by low degree melts here we report the first occurrence of diamond in the modern oceanic mantle

micrometer scale cavities in fibrous and cloudy diamonds a glance into diamond dissolution events abstract micrometer sized internal cavities in diamonds preserve evidence of diamond dissolution events combining the methods of focused ion beam fib sample preparation and transmission electron microscopy tem enables these features to be studied in detail micrometer scale cavities are found in the inner parts of fibrous and cloudy kimberlitic diamonds their filling consists of amorphous matrix secondary nano crystals volatiles and in some cases larger resorbed crystals trapped minerals include corundum kappa alumina quartz olivine moissanite 6h and ca mg carbonates this is the first observation of kappa alumina in nature secondary nano minerals are observed within the amorphous matrix and include carbonates al oxide fluorite ilmenite and secondary diamond crystals the amorphous matrix is spongy and its composition is dominated by amorphous carbon nitrogen chlorine and also contains water when no crystalline phases are observed the matrix is also enriched in alumina silica and in some cases calcium we propose that micrometer scale cavities in diamonds form during dissolution events induced by the introduction of oxidizing hydrous fluids into the diamond growth area hydrous fluids are the main dissolving agents for most kimberlitic diamonds fedortchouk y canil d semenets e 2007 mechanisms of diamond oxidation and their bearing on the fluid composition in kimberlite magmas am mineral 92 1200 1212 at diamond forming conditions silica and alumina are enriched in hydrous fluids that are in equilibrium with eclogites kessel r ulmer p pettke t schmidt m w thompson a b 2005 the water basalt system at 4 to 6 gpa phase relations and second critical endpoint in a k free eclogite at 700 to 1400 c earth planet sci lett 237 873 892 this is consistent with the increased solubility of alumina with increased pressure and temperature in the na cl bearing fluids manning c e 2006 mobilizing aluminum in crustal and mantle fluids j geochem explor 89 251 253 manning c e 2007 solubility of corundum kyanite in h2o at 700c and 10 kbar evidence for al si complexing at high pressure and temperature geofluids 7 258 269 additionally hydrous fluids may leach grain boundaries that are enriched in alumina in peridotitic environments hiraga t anderson i m kohlstedt d l 2004 grain boundaries as reservoirs of incompatible elements in the earth s mantle nature 427 699 703 wirth r 1996 thin amorphous films 1 2 nm at olivine grain boundaries in mantle xenoliths from san carlos arizona contrib mineral petrol 124 44 54 diamond dissolution will form oxidized carbon species and may decrease the solubility of silica and alumina in the dissolving agent leading to their precipitation diamond forming fluids that are trapped in sub micrometer inclusions in the same fibrous diamonds are the dominant fluid component in the diamond growth area corrosive hydrous fluids are less common and appear as short discrete events followed by the return of the common diamond forming fluids and continued diamond precipitation

rates and mechanisms of isotopic exchange background the proliferation of stable isotope laboratories in recent years has led to a marked increase in the routine use of stable isotope analyses in geochemical studies this trend is likely to continue because of the development of micro analytical techniques e g laser ablation ion microprobe femtomole carrier gas methods etc for stable isotope analysis and the potential of these techniques to reveal the detailed sequence of thermal and fluid histories preserved in the rock record see mckibben et al 1998 equilibrium isotope fractionation factors and rates of isotopic exchange form the cornerstones for the interpretation of stable isotope data from natural systems indeed determination of the distribution of the stable isotopes of c o h s in gases fluids and minerals has become a standard and extremely powerful approach in elucidating the temperatures material fluxes rock and fluid origins and time scales associated with ancient and active fluid rock interaction processes in the earth s crust see valley et al 1986 although the thermodynamic principles underlying isotopic fractionation behavior were developed more than fifty years ago by urey 1947 the calibration of fractionation factors has proven to be difficult during the last four decades a great deal of progress has been made in determining the equilibrium fractionations of 18o 16o d h 13c 12c and 34s 32s among fluid and mineral components at high temperatures 400 c both from experimental exchange studies theoretical calculations using vibrational spectra semi empirical calculations using bond type considerations and empirical calibrations based on natural assemblages see references in o neil 1986 kyser 1987 criss 1991 1999 chacko et al this volume of these the experimental method is the most direct because it involves the least number of a priori assumptions despite the utility of the equilibrium approach in quantifying the isotopic behavior in select water rock

nitrogen and 13c content of finsch and premier diamonds and their implications the nitrogen content and state of aggregation have been determined spectroscopically for diamonds from the finsch 93 and the premier 116 kimberlite south africa the ranges of concentration for diamonds with eclogitic e type and peridotitic p type mineral inclusions are finsch e type 29 to 1639 ppm p type 7 to 1206 ppm premier e type 15 to 1359 ppm p type 7 to 1086 ppm in both kimberlites nitrogen free diamonds type ii contain less frequently eclogitic inclusions among e type diamonds there are none of type ii in the finsch and 1 in the premier sample suite for p type diamonds the respective percentages are 29 and 25 there is no significant difference in the nitrogen aggregation state between e type and p type diamonds within each kimberlite however there is a significant difference between the two locations the nitrogen in the b form amounts to 26 29 n 65 in finsch and to 48 26 n 101 in premier diamonds no correlation between 13c and nitrogen content or aggregation state is observed however within the eclogitic and peridotitic paragenesis groups of diamonds of very similar nitrogen concentration 13c and mineral inclusion composition can be recognized one of these may be common to both kimberlites some of the diamonds in the two kimberlites may have had a common origin but subsequent thermal histories which differed for the sample suites from the two diatremes the nitrogen content of the diamonds is a function of local nitrogen concentration temperature and oxygen fugacity the dependence on the last of these can cause complex relationships between 15n 13c and nitrogen content of diamonds

multiple origins of alluvial diamonds from new south wales australia in eastern australia diamonds occur in alluvial deposits overlying phanerozoic basement the origin of the diamonds is not known no feeder pipes of kimberlite or lamproite are known and none of the usual diamond indicator minerals occurs in association with the diamonds alluvial diamonds from wellington bingara copeton and airly mountain in new south wales form two distinct groups here termed a and b group a diamonds are similar to those found in kimberlites and lamproites globally and are thought to have formed in precambrian lithospheric mantle group b diamonds have unusual characteristics that indicate they formed in a subduction environment surface features of diamonds of both groups indicate that all were brought to the surface by magmas group a diamonds are similar in primary crystal form internal structure mineral inclusion composition mainly peridotitic and carbon isotopes to diamonds found in kimberlitic and lamproitic hosts in archean and proterozoic cratons worldwide re os ages 3 4 and 2 1 ga pearson et al 1998 of sulfide inclusions in two group a diamonds constrain the origin of these diamonds to ancient mantle sources this along with the nature of the surface abrasion structures and radiation damage suggests that the group a diamonds represent an older group of diamonds that have been in secondary collectors for a significant time if this is so it is feasible that the group a diamonds may have been derived from a number of primary sources including possible sources in antarctica group b diamonds are unlike any other diamond suites worldwide in their combination of shape surface features strained and irregular internal structures 13c enrichment and ca rich eclogitic mineral inclusions the features are best explained as a product of diamond growth under varying p t conditions in a high p t dynamic environment such as a subducting slab the diamonds may well have formed during arc continent collision at the time of the development of the new england fold belt this would explain why the major known concentration of group b diamonds is within the new england fold belt at copeton and bingara and is consistent with the phanerozoic ages for diamond emplacement determined from mineral inclusions

mineralogical and compositional changes in bones exposed on soil surfaces in amboseli national park kenya diagenetic mechanisms and the role of sediment pore fluids abstract bones exposed on tropical savannah grasslands of amboseli national park kenya undergo extensive post mortem alteration within 40 years a combined analytical approach involving tem microscopy trace metal analysis ftir spectroscopy and petrographic analysis has revealed a complex dynamic diagenetic environment operating within exposed bones driven by evaporative transport of soil water from the bone soil interface to the upper exposed surface of the bone this process results in extensive bone soil water interaction and is responsible for increases in the concentrations of trace elements such as ba and la of 100 1000 within 15 years the maximum and mean size of bone crystallites increases with continued exposure this change in mean crystallite length is correlated positively with increases in bone crystallinity which in turn is associated with degradation of the bone protein microbial decomposition is rarely observed in the amboseli bones but where present resulted in severe dissolution reprecipitation of bone mineral many bones showed extensive permineralization of the larger vascular spaces with calcite and barite and to a lesser extent crandallite permineralization of unburied bones may account for 95 reduction in macro micron millimeter scale porosity in the bone within 2 years of death we produce a model for pre burial diagenesis of bone in arid tropical environments that highlights extensive alteration of bone chemistry within 1 40 years post mortem

coesite in the straumen kyanite eclogite pod norway the occurrence of coesite in the straumen kyaniteeclogite pod in the western gneiss region wgr norway is described although the microtextures of coesite and of its partial or complete transformation into quartz are similar to those described at the first coesite occurrence in norway the grytting dolomite eclogite pod there are some significant differences at this second locality these include the host mineral of the sio2 inclusions being garnet instead of clinopyroxene and also occasionally kyanite an initial coesite eclogite sub facies paragenesis was followed by a quartz eclogite sub facies paragenesis which in addition to rutile and dolomite or calcite contains the highest number 7 of silicate phases known in any norwegian eclogite garnet clinopyroxene kyanite quartz phengite zoisite and clinoamphibole this second occurrence of definite coesite i consolidates the very high pressury estimates about 30 kbar minimum previously deduced for certain eclogite pods occurring in the wgr and ii justifies the recognition of the norwegian coesite eclogite province constituted of a nappe terrane of about 30 kbar parageneses now residing in the wgr

a study of the forcing of the 22 25 june 2006 coastally trapped wind reversal based on numerical simulations and aircraft observations abstract coastally trapped wind reversals ctwrs occur periodically in the lowest several hundred meters of the marine boundary layer west of california and disrupt the northerly flow that typically occurs during summer south winds and coastal fog or low stratus accompany the ctwr which propagates northward along the coast a ctwr was observed off the california coast during late june 2006 that originated in the california bight and propagated northward to cape mendocino during the subsequent 2 day period this ctwr event was explored by the university of wyoming king air research aircraft to document the primary characteristics of the wind reversal numerical simulations of the ctwr event using the weather research and forecast modeling system were conducted to compare with observations and to provide a broader picture of the ctwr structure and evolution an analysis of the forcing mechanisms responsible for the june 2006 ctwr event is presented it is demonstrated that the mature ctwr for this case i

diamond nucleation and growth by reduction of carbonate melts under high pressure and high temperature conditions we report for the first time experimental evidence for the nucleation and growth of diamonds from carbonatitic melts by reduction in reactions with silicon metal or silicon carbide experiments were carried out in the camg co 3 2 si and camg co 3 2 sic systems at 7 7 gpa and temperatures of 1500 1800 c no graphite was added to the run powder as a carbon source the carbonate bearing melts supply the carbon for diamond formation diamond grows spontaneously from the carbonatitic melt by reducing reactions camg co 3 2 2si camgsi 2 o 6 2c in the camg co 3 2 si system and camg co 3 2 2sic camgsi 2 o 6 4c in the camg co 3 2 sic system our results provide strong experimental support for the view that some natural diamonds crystallized from carbonatitic melts by metasomatic reducing reactions with mantle solid phases

nitrogen and carbon isotopic composition in the diamonds of mbuji mayi zaire the concentration and isotopic composition of nitrogen measured in large diamonds gram size from the mbuji mayi kimberlite district zaire show a large range of variation 100 n 2100 ppm 11 2 15n 6 0 the15n depleted nitrogen is associated with the higher nitrogen concentrations the large diamonds are individually rather homogeneous in13c range of 13c 0 9 while variations occur within small octahedral diamonds from the same district range up to 5 8 the total range of 13c variation is about the same for the large diamonds 10 5 13c 5 5 the small octahedral diamonds 10 13c 4 6 and the carbonates from local kimberlites 11 8 13c 5 5 the diamond carbon isotopic data could indicate a complex story of crystallization within a deep seated system fractionating its carbon isotopes the nitrogen results indicate that nitrogen in diamonds is on the average markedly depleted in15n weighted average 5 15 relative to atmosphere sediments and upper mantle

experimental investigation of silicate carbonate system at high pressure and high temperature melting and subsolidus relations in the mg fe sio3 m fe co3 mg fe 2 sio4 mg fe co3 and mg fe o me fe co2 systems have been investigated at 14 15 16 and 25 gpa 1973 k and 2173 k using a 1000 t uniaxial multi anvil split sphere apparatus the iron magnesium partition coefficients between magnesite and silicates or oxides have been measured in subsolidus assemblages iron is always partitioned preferentially in the silicate and oxide phases the order of increasing partitioning being pyroxene olivine silicate perovskite wadsleyite and magnesiowustite a thermodynamic model of iron magnesium distribution between magnesite and all these phases based on gibbs free energy minimization is established melting of pyroxene magnesite and olivine magnesite pseudo binary systems is eutectic with eutectic points close to 1973 k and 60 mol carbonate at 15 gpa in both systems in the more complex mantle system it is likely that such melts would form in the transition zone by heating and homogenization of deep subducted carbonates the melts formed in the olivine carbonate system are characterized by high mg fe si ratios and thus unlikely to be primary kimberlitic magmas a conclusion in agreement with previous studies in the peridotite co2 system on the other hand the observed pyroxene magnesite melts formed at transition zone conditions have mg fe si ratios that are comparable to those of natural kimberlites suggesting that melting of carbonated pyroxenites at high pressures could be a source of kimberlitic magmas

simulation of a north american monsoon gulf surge event and comparison to observations abstractgulf surges are transient disturbances that propagate along the gulf of california goc from south to north transporting cool moist air toward the deserts of northwest mexico and the southwest united states during the north american monsoon they have been shown to modulate precipitation and have been linked to severe weather and flooding in northern mexico and the southwest united states the general features and progression of surge events are well studied but their detailed evolution is still unclear to address this several convection permitting simulations are performed over the core monsoon region for the 12 14 july 2004 gulf surge event this surge event occurred during the north american monsoon experiment which allows for extensive comparison to field observations a 60 h reference simulation is able to reproduce the surge event capturing its main characteristics speed and direction of motion thermodynamic changes during its passage and strong northward moisture flux while the ti

terrestrial carbon and nitrogen isotopic ratios from cretaceous tertiary boundary nanodiamonds one hypothesis for the origin of the nanometer size diamonds found at the cretaceous tertiary k t boundary is that they are relict interstellar diamond grains carried by a postulated asteroid the 13 c 12 c and 15 n 14 n ratios of the diamonds from two sites in north america however show that the diamonds are two component mixtures differing in carbon and nitrogen isotopic composition and nitrogen abundance samples from a site from italy show no evidence for either diamond component all the isotopic signatures obtained from the k t boundary are material well distinguished from known meteoritic diamonds particularly the fine grain interstellar diamonds that are abundant in primitive chondrites the k t diamonds were most likely produced during the impact of the asteroid with earth or in a plasma resulting from the associated fireball

interaction of a warm season frontal system with the coastal mountains of the western united states part i prefrontal onshore push coastal ridging and alongshore southerlies abstract observational analyses and numerical simulations are used to investigate the interaction between a warm season frontal system trough and the complex terrain of the western united states prior to frontal landfall synoptically driven offshore flow was associated with the northward development of a thermal trough and a coastal pressure ridge and associated southerly winds moved northward along the coasts of northern california oregon washington and southwestern british columbia this coastal pressure ridge coupled with the subsequent weakening of the offshore flow resulted in the onshore push of cool marine air approximately 24 h before frontal passage the onshore surge of cool marine air into warm dry continental air associated with the thermal trough produced a mesofront that moved over the coastal and cascade mountains diagnosis of a realistic simulation of the event shows that both solar heating and adiabatic warming from downslope flow over the rockies and the cascade mountains are i

small amplitude coastally trapped disturbances and the reduced gravity shallow water approximation solutions are obtained for linear hydrostatic disturbances propagating parallel to the face of an uninterrupted topographic step in an infinitely deep stably stratified fluid on an plane these waves are vertically trapped because their frequencies are smaller than the coriolis parameter and the height of the topographic step is finite these waves are referred to as step trapped kelvin waves because they are dynamically similar to internal kelvin waves throughout the layer of fluid below the top of the topographic step these waves appear to provide an idealized semi analytic model for the coastally trapped disturbances observed to propagate parallel to mountainous coastlines in several parts of the world computations are performed for a basic state with uniform static stability and for a three layer basic state in which the two lowest layers represent the marine boundary layer and a strong capping inversion one might suppose that the linear dynamics of hydrostatic disturbances in the three layer basic state could be well approximated by a reduced gravity shallow water model but this is not the case in particular the reduced gravity shallow water model does not provide reliable estimates for the phase speed of linear step trapped kelvin waves this defect suggests that detailed quantitative comparisons between marine boundary layer flows and the reduced gravity shallow water system may not have any intrinsic physical significance nevertheless these results do not preclude the possibility of constructing useful qualitative analogies between marine boundary layer flows and the reduced gravity shallow water model

the relationship between tropical easterly waves and surges over the gulf of california during the north american monsoon abstract coastally trapped disturbances which occur over the gulf of california and are commonly referred to as gulf surges are an important mechanism in the transport of low level moisture into the southwestern united states to determine whether or not gulf surges develop in association with the passage of tropical easterly waves as hypothesized in previous studies standard surface observations and european centre for medium range weather forecasts reanalysis data during the months of july and august over a 14 yr period are examined results indicate that tropical easterly wave troughs often cross western mexico 1 3 days prior to surge onset at yuma arizona indicating a strong correlation between these two events this analysis documents yet another mechanism by which the tropics influences convection in the midlatitudes

sulfide melts graphite interaction at hpht conditions implications for diamond genesis abstract the interaction of graphite with fe ni 9s8 and fes sulfide melts has been studied at p 6 3 7 5 gpa and t 1450 2200 c in experiments with a duration from 2 to 65 h it has been found that both pentlandite and pyrrhotite melts interacting with graphite show similar behavior at

early diagenetic evolution of bone phosphate an x ray diffractometry analysis abstract a new crystallinity index ci based on the x ray powder diffractometric pattern of fossil bone carbonate hydroxylapatite is defined this ci value provides a semi quantitative way to estimate the diagenetic changes in archaeological and palaeontological bone phosphate the studied samples are 71 human bones from the french merovingian cemetery of saint linaire 1200 1700 bp 37 human bones from two necropoleis in niger 1000 5000 bp two cave bear bones from aldene cave southern france around 70 000 bp five bones of miocene mammals and 14 bones of mesozoic reptiles the main results are that 1 there is no correlation between the increase in the ci and the age of the sample even in one given locality 2 the ci seems to be related to the taphonomical conditions in archaeological and fossil bones 3 an increase in the ci is correlated with a loss in organic matter in one archaeological site but the quality of preservation of organic matter in fossil bones does not depend on the changes in the ci 4 the correlation between the increase in the ci and the decrease of co3amount in bones from the niger necropolies suggests a possible mechanism for the increase in crystallinity the changes of crystallinity reflect early diagenetic changes and depend on the burial environments

surges over the gulf of california during the mexican monsoon abstract northward surges of relatively cool moist maritime air from the tropical pacific into the southwestern united states occur via the gulf of california every summer during the mexican monsoon season these surges advect large amounts of moisture northward and promote increased convective activity in arizona mesoscale model output from 32 successive 24 h simulations are used to examine both the large scale and mesoscale features associated with surge events model data are compared to high resolution aircraft measurements on two days showing clearly that the model is capable of reproducing many of the detailed structures found in the observations results from a large scale analysis indicate that strong surges are produced in the model when a midlatitude trough is in the proper phase relationship with a tropical easterly wave weak surges occur when this relationship is missing

reconstructing taphonomic histories using histological analysis abstract recent years have seen rapid advances in the understanding of diagenetic changes to bone tissues and how these influence the chemistry microstructure and histological appearance of ancient bone it is now possible to recognise many characteristic features of diagenetically modified bone and this has led to the potential use of these parameters in estimating the potential survival of biogenic signals such as dna lipids proteins and stable isotopes these characteristic features also hold the potential for preserving a record of different post mortem environments in individual bones or assemblages of bones from the same site in sites where the burial conditions have changed over archaeological or geological timescales histological analyses can shed light on these different burial environments and permit the reconstruction of taphonomic histories of some bones examination of polished sections of bone using bse sem has been used to identify characteristic features attributed to aerobic soil bacteria cyanobacteria and sulphate reducing bacteria the approach shows promise for providing supplementary evidence when phasing complex sites such as graveyards which developed over several hundred years

bone diagenesis variability among multiple burial phases at al khiday sudan investigated by atr ftir spectroscopy abstract in this study the diagenetic pathways of archaeological human bones are investigated through fourier transform infrared spectroscopy in attenuated total reflection mode atr ftir archaeological excavations at al khiday 16 d 4 site khartoum sudan revealed a multi stratified cemetery with distinct burial phases chronologically attributed to different periods spanning from the early holocene to the beginning of the 1st millennium ce atr ftir measurements are carried out on a set of 56 bone samples representative of each burial phase parameters related to collagen content and to bioapatite crystallinity and structural carbonate are calculated from infrared spectra in order to monitor the types and extent of diagenetic alteration to assess the preservation state of bones and to define the alteration processes occurring during burial a new method is here developed to quantify the amount of secondary calcite and to remove its contribution to the infrared spectrum when interfering with the signal of structural carbonate from bioapatite considering the wide span of time covered by the archaeological record the variability of bones alteration among burial phases is related to the climatic changes occurring in central sudan during the holocene the more humid environment occurring in the early holocene characterised by higher precipitation rates seasonal swamps and palaeo lakes progressively changed towards drier conditions until the current arid climate of the sub saharan belt the change of palaeoenvironmental and local burial conditions over time differently influenced the types and extent of diagenetic processes affecting bones during burial in this research are also discussed advantages and disadvantages of atr ftir spectroscopy with respect to the more established ftir spectroscopy in transmission mode

investigating intra bone isotopic variations in bioapatite using ir laser ablation and micromilling implications for identifying diagenesis abstract the potential of in situ microsampling micromilling and ir laser ablation to detect intra sample isotopic variation resulting from diagenesis and or natural remodeling of bone was examined in this study modern sheep bones were exposed to microbial populations to induce diagenesis and the 13 c and 18 o values of bioapatite structural carbonate and phosphate were determined for these samples and for diagenetically modified archaeological samples from three different environments no significant differences were found between the 13 c laser or 18 o laser values of microbially colonized and uncolonized areas on the modern bone surfaces or between well preserved and poorly preserved regions of the archaeological material however high degree of intra sample variation was observed in values obtained using ir laser ablation some of which arose from methodological challenges associated with this method further 13 c values obtained using ir laser ablation were lower than those acquired by conventional analysis likely because of contamination from organic matter in the samples isotopic compositions of structural carbonate samples obtained by micromilling were less variable for both methods however significant differences in 13 c and 18 o values were observed for different bone surfaces these variations may indicate differences in the isotopic compositions of food and water incorporated into osteons over a lifetime and illustrate the relationship between bone remodelling and isotopic heterogeneity in bone overall our results highlight the difficulties of using the ir laser ablation method for measuring isotopic compositions of bone

multiple growth events during diamond genesis an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stones the internal structure and growth history of diamonds have been investigated by the study of carbon isotopes and the abundance isotope composition and aggregation state of nitrogen polished plates of zoned diamonds coated stones were laser sectioned for infrared mapping and isotope profiling nine small cubic and three small octahedral diamonds from zaire and two coated stones and five small cubic diamonds specifically from the mbuji mayi area of that country were also investigated the isotope composition and infrared characteristics of the diamonds of cubic habit including coats were found to be indistinguishable with 13c in the range 5 9 to 7 5 and all the nitrogen being present as the paired structure iaa with a 15n of between 3 1 and 8 0 the diamonds of octahedral habit including the cores of the coated stones were more variable 13c varied from 4 9 to 9 8 infrared spectra of the octahedral diamond exhibited either strong iaa characteristics or a combination of iaa and iab platelets were present in most cases 15n values from octahedral diamonds varied from 5 8 to 13 4 the data suggest that the octahedral diamonds represent a variety of growth events separated in time and or space and that the diamonds resided in the lithosphere for a period sufficient for thermal maturation in the case of the coated stones the octahedral diamonds were later involved in an event which added a component from a single relatively homogeneous reservoir cubic habit diamonds were formed at the same time this latter event is believed to be related to the kimberlite eruption comparison of the data with carbon isotope analyses of cubic diamond from other sources suggests that this reservoir could be widespread

mantle related carbonados geochemical insights from diamonds from the dachine komatiite french guiana abstract carbonado is a unique type of polycrystalline diamond characterised among others by 13c depleted isotope compositions 13c 25 vs pdb little advanced nitrogen aggregation ib iaa and sintered ceramic like diamond grains its origin remains an enigma with models proposing a formation either in the earth s crust or even within an exploding super nova the possibility that carbonado formed in the earth s mantle is often rejected because diamond with carbonado like geochemical features has never been found in rocks such as kimberlites that carry diamonds from the mantle in this study it is shown that the c and n stable isotope compositions nitrogen contents and nitrogen speciation of diamonds from the dachine komatiite french guyana exhibit unambiguous similarities with carbonados these include c isotopes from 32 6 to 0 15 mode at 27 n aggregation only ib iaa diamonds from 2 to 76 of n pairs and n isotopes from 4 1 to 6 9 average 2 1 2 9 which all strikingly match the carbonado data this evidence illustrates that the main geochemical arguments usually called to reject a mantle origin of carbonado are no longer valid a model linking carbonado crystallisation from komatiite volatiles is developed in this model the sintering is produced by the high temperature of the komatiite magma thus accounting for their absence in colder kimberlites the low 13c compositions of carbonados would be inherited from the transition zone 300 km depths which is known to yield diamonds with distinct c isotope distributions compared to most lithospheric diamonds 150 300 km depths this model can account for most available observations of carbonados including their large size sintering photoluminescense cathodoluminescence features and geochemical characteristics

examining histology to identify burned bone abstract early research suggests that examination of the microscopic internal structure is a valid method for distinguishing burned from unburned bone in the archaeological record this study compares burned and unburned modern bones with archaeological bones from sibudu cave ca 60 000 years ago and cave of hearths over 200 000 years ago to more fully describe the heat induced histological changes to bone we also explore the effects of diagenesis on those changes to determine if histological evidence of burning preserves through fossilisation and diagenetic processes and can be successfully used to identify ancient burning application of this technique can help in addressing various issues including the origins of controlled use of fire and understanding animal butchery and disposal