average seasonal variation of the atlantic equatorial currents from historical ship drifts abstract surface currents in the tropical atlantic were studied using historical ship drift data these are the only available data capable of resolving the long term seasonal fluctuations of currents over a broad geographical region the north equatorial countercurrent was found to extend as a continuous eastward flowing current across the atlantic in the band 5 8 n from july to december the maximum average eastward velocity was 30 cm s 1 during july september east of 20 w the countercurrent continued throughout the year west of 20 w and from january to june the countercurrent disappeared and westward currents were observed average westward velocity reached 20 cm 1 in april and may centered near 40 w the annual cycle in surface velocity 20 cm s 1 amplitude agrees closely with that of geostrophic velocity inferred from variations in thermocline depth across the counter current jets centered near 2 n and 4 s separated by a minimum near 1 s the northern jet has a large 14 cm s 1 semiannual v

estimating thermal inflow to el chichon crater lake using the energy budget chemical and isotope balance approaches abstract el chichon crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed 1 km wide explosive crater during the first 2 years after the eruption the lake transformed from hot and ultra acidic caused by dissolution of magmatic gases to a warm and less acidic lake due to a rapid magmatic to hydrothermal transition input of hydrothermal fluids and oxidation of h 2 s to sulfate chemical composition of the lake water and other thermal fluids discharging in the crater stable isotope composition d and 18 o of lake water gas condensates and thermal waters collected in 1995 2006 were used for the mass balance calculations cl so 4 and isotopic composition of the thermal flux from the crater floor the calculated fluxes of thermal fluid by different mass balance approaches become of the same order of magnitude as those derived from the energy budget model if values of 1 9 and 2 mmol mol are taken for the catchment coefficient and the average h 2 s concentration in the hydrothermal vapors respectively the total heat power from the crater is estimated to be between 35 and 60 mw and the co 2 flux is not higher than 150 t day or 200 gm 2 day 1

the relationship of sea surface temperature to thermocline depth at annual and interannual time scales in the tropical atlantic ocean expendable bathythermograph data derived from sequal focal and toga sponsored volunteer observing ship programs in the tropical atlantic ocean are used to study the relationship between the sea surface temperature sst and the underlying thermocline time series up to 8 years long allow investigation of both the annual and interannual variability between 2n and 2s along selected shipping lanes for the annual harmonic a warm sst is correlated with a shallow thermocline everywhere except in the eastern equatorial region near the intertropical convergence zone itcz the 180 phase shift in the annual harmonic of both the sst and the thermocline depth occurs at slightly different latitudes over most of the tropical atlantic the annual cycle of sst is linked to the phase of the net surface heat flux and only in the eastern equatorial and coastal upwelling regions does heat flux across the thermocline become a significant factor for the annual cycle of the sst canonical correlation analysis of the interannual variability reveal two distinct modes with structures similar to the annual cycle the first in which a warm sst is correlated with a shallow thermocline is a dipole with centers of maximum amplitude off the equator at approximately 8s at 12n and a node at the itcz the second mode for which a warm sst is correlated with a deep thermocline peaks at the equator the predominance of the first mode suggests that for most of the tropical atlantic ocean the dynamical state beneath the surface mixed layer has only a limited influence on sst fluctuations

investigating compositional diversity among fijian ceramics with laser ablation inductively coupled plasma mass spectrometry la icp ms implications for interaction studies on geologically similar islands this paper presents a ceramic provenance analysis of 260 fijian sherd clays by laser ablation inductively coupled plasma mass spectrometry la icp ms our analyses define three compositional groups in western fijian ceramics distributed across the 2700 year ceramic sequence frequencies of compositional groups represented in the diachronic assemblages indicate an increasing spatial sphere of interaction until approximately 1500 bp by 1000 bp interaction had spatially contracted to a significant degree these findings suggest re evaluation of current ideas about interaction in the southwest pacific is necessary

on the origin of el chichon volcano and subduction of tehuantepec ridge a geodynamical perspective the origin of el chichon volcano is poorly understood and we attempt in this study to demonstrate that the tehuantepec ridge tr a major tectonic discontinuity on the cocos plate plays a key role in determining the location of the volcano by enhancing the slab dehydration budget beneath it using marine magnetic anomalies we show that the upper mantle beneath tr undergoes strong serpentinization carrying significant amounts of water into subduction another key aspect of the magnetic anomaly over southern mexico is a long wavelength 150 km high amplitude 500 nt magnetic anomaly located between the trench and the coast using a 2d joint magnetic gravity forward model constrained by the subduction p t structure slab geometry and seismicity we find a highly magnetic and low density source located at 40 80 km depth that we interpret as a partially serpentinized mantle wedge formed by fluids expelled from the subducting cocos plate using phase diagrams for sediments basalt and peridotite and the thermal structure of the subduction zone beneath el chichon we find that 40 of sediments and basalt dehydrate at depths corresponding with the location of the serpentinized mantle wedge whereas the serpentinized root beneath tr strongly dehydrates 90 at depths of 180 200 km comparable with the slab depths beneath el chichon 200 220 km we conclude that this strong deserpentinization pulse of mantle lithosphere beneath tr at great depths is responsible for the unusual location singularity and probably the geochemically distinct signature adakitic like of el chichon volcano

seismicity and structure in central mexico evidence for a possible slab tear in the south cocos plate the morphology of the transition from flat to normal subduction in eastern central mexico is explored using intraslab earthquakes recorded by temporary and permanent regional seismic arrays observations of a sharp transition in slab dip near the abrupt end of the trans mexican volcanic belt tmvb suggest a possible slab tear located within the subducted south cocos plate the eastern lateral extent of a thin ultra slow velocity layer usl imaged atop the cocos slab in recent studies along the meso america subduction experiment array is examined here using additional data we find an end to this usl which is coincident with the western boundary of a zone of decreased seismicity and the end of the tmvb near the sharp transition in slab dip waveform modeling of the 2 d structure in this region using a finite difference algorithm provides constraints on the velocity and geometry of the slab s seismic structure and confirms the location of the usl analysis of intraslab seismicity patterns reveals clustering sudden increase in depth variable focal mechanism orientations and faulting types and alignment of source mechanisms along the sharp transition in slab dip the seismicity and structural evidence suggests a possible tear in the south cocos slab this potential tear together with the tear along the orozco fracture zone to the northwest indicates a slab rollback mechanism in which separate slab segments move independently allowing for mantle flow between the segments

comparison of methods for the removal of diagenetic material in buried bone abstract three excavated human femurs from the middle woodland gibson site in west central illinois and six from the late intermediate estuquina site in peru have been subjected to four different cleaning procedures prior to elemental analysis a simple brushing and washing with distilled water b physical removal of 1 3 mm of both the outer and the inner surfaces by abrasion c treatment of powdered bone with 1 n acetic acid d sequential washing of powdered bone with acetate buffer analyses were carried out on subsequently ashed material levels of calcium of organics and of metallic soil constituents iron manganese aluminium give an overall indication of contamination and diagenesis physical abrasion method b is effective in removing bone surface contaminants particularly iron manganese aluminium potassium and zinc chemical procedures permit removal of diagenetic material throughout the bone but also remove some biogenic elements that are present on the surface of the bone crystals effects of biogenic constituents were tested by analysing rat pelvic bones that had been subjected to the same four procedures a combination of physical abrasion and mild chemical washings may provide the best procedure for preparation of bone prior to analysis

enamel diagenesis at south african australopith sites implications for paleoecological reconstruction with trace elements abstract elemental ratio data from archaeological and paleontological bone have often been used for paleoecological reconstruction but recent studies have shown that even when solubility profiling techniques are employed in an attempt to recover biogenic signals bone is an unreliable material as a result there has been renewed interest in using enamel for such studies as it is known to be less susceptible to diagenesis nevertheless enamel is not immune from diagenetic processes and several studies have suggested that paleoecologically relevant elements may be altered in fossil enamel here we investigate sr ba zn and pb compositions of enamel from south african karstic cave sites in an effort to ascertain whether or not this material provides reliable paleoecological information we compared enamel data for mammals from three fossil sites aged 1 8 3 0 ma all of which are on dolomites with data from modern mammals living on dolomitic and granitic substrates sr ca and ba ca are about three times higher in enamel from modern mammals on granites than those living on dolomites stressing the need for geologically appropriate modern fossil comparisons after pretreatment with dilute acid we found no evidence of increased sr ca ba ca or pb ca in fossil enamel in contrast zn ca increased by over five times at one site makapansgat but much more subtly elsewhere ecological patterning in sr ca ba ca and sr ba ratios was also retained in fossil enamel this study suggests that sr ca ba ca and pb ca data likely preserve paleoecological information from these sites but also demonstrates that geologically similar sites can differ in the degree to which they impart certain elements zn in this case to fossils thus screening is probably necessary on a site by site basis lastly further investigation of elemental distributions in modern foodwebs is necessary before elemental ratio analysis can become a common tool for paleoecological reconstruction

the colima volcanic complex mexico part ii late quaternary cinder cones since the late pleistocene eleven cinder and lava cones have erupted on the floor of the southern colima graben ne and nw of the large active andesitic volcano colima scoria and lava samples from nine of the cones form a completely transitional basic alkalic series including basanites 9 leucite basanites 3 and minettes 15 the commonest variety of mica lamprophyre these samples represent primitive high temperature magmas with 47 6 50 3 sio2 7 4 15 3 mgo 2 5 4 4 k2o and 2 2 9 9 normative nepheline all members of this basic alkalic suite contain mg olivine fo75 94 chromite augite and late plagioclase and titanomagnetite the petrographic transition from basanite to minette is marked by the appearance of sanidine and the volatile bearing phases phlogopite apatite and analcime during late stages of crystallization as these phases increase in abundance presumably reflecting a rise in magmatic volatile content there are corresponding increases in the whole rock concentrations of 16 incompatible elements although these incompatible elements are relatively abundant even in the basanites many are highly concentrated in the minettes ba 4 200 ppm sr 3 100 ppm zr 550 ppm ce 190 ppm hf 18 ppm among the incompatible elements the degrees of enrichment in the minettes relative to the basanites decrease in the order h th ce la nd zr hf u ba sm eu pb p nb sr ti these enrichments may reflect the increasing importance of minor incompatible element rich mantle phases during partial melting the concentrations of alkali metals k na rb and cs do not correlate with these other elemental enrichments the leucite basanties have similar incompatible element contents to many minettes differing from them only in the presence of leucite rather than analcime and ti f rich groundmass phlogopite rather than hydrous phlogopite phenocrysts thus the leucite basanites represent relatively dry equivalents of minettes two of the eleven cinder cones are calc alkaline in nature and do not belong to the basanite minette group the easternmost cone is constructed of high al basalt and the northernmost of basaltic andesite the high al basalt 49 5 sio2 9 3 mgo 221 ppm ni closely approximates a parental magma to the post caldera andesitic suite of v colima 56 5 61 6 sio2 the basaltic andesite is relatively enriched in incompatible elements compared to the high al basalt v colima trend the ne normative basanite minette samples are highly enriched in incompatible elements while the contemporaneous hy qz normative calc alkaline suite encompassing the high al basalt and v colima s andesites is characterized by relatively low abundances of these elements no likely mineral assemblage can relate the alkaline and calc alkaline suites through crystal fractionation they probably represent fundamentally different melting events during the quaternary the main focus of andesitic volcanism in the southern colima graben has migrated southward with time volcan colima marks its present position 5 km south of the pleistocene volcano nevado de colima and another 15 km from the still older volcan cantaro the eruptions of basic alkalic magma probably occurred during the late stages of nevado s life and through the life of v colima they generally migrated from west to east with time towards v cantaro the most recent cone v apaxtepec is the only one east of the andesitic colima cantaro axis the oldest and the two youngest cones produced basanites while minettes dominated at cones of intermediate ages the cinder cone eruptions may have coincided with a phase of lamprophyre dike injection into plutons solidifying beneath the extinct volcanoes north of v colima the southern end of the colima graben can be viewed then as the volcanic analog of many classical post plutonic hypabyssal lamprophyre localities

near equatorial eddies in the north atlantic surveys of the large scale near equatorial eddies 400km across off the northeast coast of south america with expendable bathythermographs from ships of opportunity and aircraft indicate that a large eddy 6n 11n to the north and a southern eddy like feature 2n 6n probably are a permanent part of the circulation both features were observed during the periods of seasonal extremes march and september although during the latter period the structure of the eddies had enlarged and deepened indicating a pronounced seasonal variability

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

the relationship between quaternary volcanism in central mexico and the seismicity and structure of subducted ocean lithosphere late quaternary volcanism in central mexico is related to the subduction of young ocean lithosphere at the middle america trench along arc variations in seismicity volcano structure and composition of volcanic products bear a remarkable correlation with the age and structural framework of the downgoing slab morphological and petrographic characteristics of major volcanoes within the trans mexican volcanic belt tmvb serve to distinguish two calc alkaline subprovinces 1 a western arc averaging 60 km in width associated with aseismic subduction of the rivera plate the main cones of this region are dominated by two pyroxene andesites comprise volumes 70 km 3 and stand less than 3 000 m above sea level 2 a broad central and eastern arc related to subduction of a gently inclined segment of the cocos plate bounded by the rivera transform and the tehuantepec ridge major volcanic edifices possess summit elevations in the range 4 000 to 6 000 m have appropriately larger volumes typically 200 km 3 and are constructed with a high proportion of amphibole bearing lavas the boundary between these subprovinces is marked by a north south oriented structural depression the colima graben and it coincides with a 100 km offset in the volcanic front extensional tectonism in the colima graben accompanied by mixed calc alkaline and alkaline volcanism of potassic affinity is likely related to a hinge type transform fault which marks the cocos rivera plate juncture in the downgoing slab a third segment of ocean floor is presently interacting with continental lithosphere south of the gulf of tehuantepec where quaternary volcanism is weakly developed within a tectonically complex region that marks the diffuse cocos noam caribbean triple junction the northern limit of this triple junction is defined by the seismically active isthmus fault which may be related to alkaline volcanic activity at san andres tuxtla a tectonic reconstruction based on the evolution of oceanic crust reveals that the distribution of intermediate depth earthquakes along the arc is directly dependent upon the age of the subducted slab ocean lithosphere younger than approximately 20 m y is subducted aseismically at convergence rates approaching 9 cm yr the length of the inclined seismic zone indicates that the time constant for thermal relaxation in the slab is approximately 4 m y the tmvb overlies the aseismic extension of this young ocean lithosphere several aspects of this study have a bearing on the segmented nature of converging margins in general 1 the tectonic evolution of the ocean floor may determine the nature of segmentation at the site of subduction 2 the complete record of volcanism in the tmvb over the past million years can be related to the present plate configuration 3 alkaline and calc alkaline volcanism have developed contemporaneously at a converging plate margin 4 lineaments in volcanic arcs may reflect the structural complexity of the crust rather than segment boundaries in the subducted slab

polarizing microscopy identification of chemical diagenesis in archaeological cementum cementum increment analysis can potentially retrieve relatively complete high precision seasonality and mortality profiles from archaeological mammalian tooth assemblages however cementum exhibits many similarities to bone in composition histology ultrastructure and even microstructure consequently the mineralized dental tissue may be prone to the same processes of post depositional chemical alteration that affect bone this article reviews the issues surrounding chemical diagenesis in cementum and presents a new application to archaeological ungulate cementum of a polarizing microscopy technique that has previously been utilized to identify the effects of chemical diagenesis in archaeological bone and human cementum geusa et al 1999 gilbert 1989 watson 1975 zeder 1978 it is argued that the post mortem leaching of collagen and the diagenetic growth of apatite crystallites can develop into banded features that mimic seasonal cementum increments this pattern of diagenesis is demonstrated in multiple locations on a macroscopically well preserved upper pleistocene age archaeological tooth which was previously interpreted by the author to exhibit biogenic seasonal cementum increments stutz 1993 stutz et al 1995 it is suggested that if researchers seek to retrieve seasonality and mortality data from archaeological cementum the microscopy analysis protocol must include screening of a pilot sample for the frequency and extent of chemical diagenesis

experimental constraints on the low pressure evolution of transitional and mildly alkalic basalts the effect of fe ti oxide minerals and the origin of basaltic andesites one atmosphere melting experiments controlled at the fayalite magnetite quartz oxygen buffer on mildly alkalic and transitional basalts from iceland show that these begin to crystallize fe ti oxide minerals magnetite and or ilmenite at 1105 5 c apparently independently of bulk composition and the order of silicate and oxide mineral crystallization most samples crystalline plagioclase and olivine as the first two crystalline phases augite as the third phase and an fe ti oxide mineral as the fourth phase the main effects of fe ti oxide crystallization are a marked decrease in feo and tio2 in the liquid and a notable increase in sio2 and al2o3 and the minor oxides k2o and p2o5 with decreasing temperature the most silicic glasses are compositionally mugearitic and shoshonitic basaltic andesites because the smallest amount of glass that could be analyzed with the microprobe represents 20 55 percent liquid remaining it can be expected that more silicic liquids will occur at lower temperatures on normative pseudoternary projections the general effect of fe ti oxide crystallization for mildly alkalic and transitional basalts is a marked increase in normative quartz this is caused by a strong systematic convergence with the appearance of fe ti oxides of the bulk solid precipitates toward the liquid compositions as projected on the triangle plagioclase diopside olivine for alkalic basalts the bulk solid precipitate shows an increase in normative diopside with falling temperature and fe ti oxide crystallization this causes the liquids to move toward decreasing normative diopside and relatively little variation in nepheline the experimental observations imply that mildly alkalic and transitional magmas without stabilizing a fe ti oxide mineral will not evolve toward early silica saturation

water masses distribution in the southern ocean improvement of an extended omp eomp analysis abstract the southern ocean so is a major part of the global ocean circulation the formation and mixing of water masses in the so cause changes in the northward flow of the meridional overturning circulation and as a consequence in the earth s climate there have been numerous studies of the so but a full understanding is difficult to achieve due to the complexity of the processes of formation and mixing of the different water masses this work aims to clarify some of these aspects through an extended optimum multiparametric analysis using data downloaded from the glodap and carina databases a total of 11 source water masses were selected accurately describe the physical and biochemical properties of the so shelf surface waters were included in order to accommodate the complex shelf processes involved in the formation of antarctic bottom waters the methodology here developed takes into account the remineralisation of organic matter and as an improvement the variability of data related to the processes of dissolution of caco 3 and opal the results from this analysis are accurate and reliable and led to very informative conclusions thus a volumetric census is presented which confirms circumpolar deep water cdw 53 3 of the so volume as the most volumetrically important water mass in the so followed by antarctic bottom water aabw 17 0 9 and north atlantic deep water nadw 13 0 8 aabw properties are the result of the predefined combination of its three major types i e 77 weddell sea bottom water 20 ross sea bottom water and 3 adelie bottom water cdw comprises 65 aabw 30 nadw and 5 antarctic intermediate water according to the relationship between their conservative properties potential temperature and salinity therefore the volume occupied by aabw and nadw in the so rises to 51 2 and 28 0 8 respectively the ratio between aabw and nadw is 1 79 0 03 which is inside the expected range of 1 3 considering the atlantic sector of the so 70 w 80 e which is the more relevant in terms of aabw production aabw represents 60 0 2 of the volume of the sector the estimated ventilation time is approximately 250 years the same period as for the whole so this demonstrates the very important role of shelf processes in the quantity of aabw formed in the so and its crucial role in terms of global climate

reconstructing middle horizon mobility patterns on the coast of peru through strontium isotope analysis the pre columbian coastal site of ancon peru frequently has been interpreted as an important outpost of the highland wari empire inhabited by individuals from the sierra and the coast in order to test this hypothesis bone tooth pairs from 35 middle horizon 550 ad 1000 ad ancon skeletons were analyzed for strontium isotopes which vary by geologic provenance results indicate that 34 of the 35 individuals have 87 sr 86 sr enamel and bone values higher than ancon s biologically available strontium isotope range nitrogen and carbon isotope data from a subset of the ancon skeletons suggest that the higher than expected 87 sr 86 sr values among the ancon sample likely reflects a diet rich in marine resources rather than migratory activity and highlight the need to use multiple lines of evidence to track residence change at sites where individuals relied on resources other than locally grown terrestrial foods the one remaining individual a young female of elite status has an enamel strontium isotope signature much lower than the available data for local fauna and soil indicating that she was not raised locally her enamel 87 sr 86 sr ratio fits well within the range of strontium isotope values established for the inland wari site of conchopata tung t a knudson k j social identities and geographical origins of wari trophy heads from conchopata peru current anthropology in press and suggests that highland wari immigrants may have been present at ancon during the middle horizon

obsidian characterization by laser ablation icp ms and its application to prehistoric trade in the mediterranean and the near east sources and distribution of obsidian within the aegean and anatolia for geological studies interest in mass spectrometry with an inductively coupled plasma as an ion source and its association with laser ablation as a sample introduction technique la icp ms has steadily increased during the past few years and is now being developed in other fields such as archaeology after a description of the analytical procedure and the calculation method we show the potential of this technique to characterize almost non destructively archaeological artefacts among the 70 elements that could be routinely analysed by la icp ms with detection limits below the ppm level we choose to determine the more critical ones in order to evaluate the geochemical models of the magmatic process major elements rare earths and some transition elements a detailed survey of cappadocian obsidian flows is given and includes the characterization of nine different sources evidence of complex trade activities is clearly shown by the obsidian tools found at different prehistoric sites from neolithic to bronze age levels in the mediterranean and the near east new results obtained on some archaeological sites located in turkey syria and cyprus are presented they show the importance of cappadocian sources in obsidian trade our results show that la icp ms allows a non destructive analysis of archaeological objects and that it combines the advantage of the different classical methods used to characterize obsidian sources mainly xrf and inaa with high sensitivity and rapidity thus la icp ms appears to be a very powerful analytical tool and at this time this technique is the only one which can non destructively determine such an important number of elements with such low detection limits

the use of soil chemistry data to address post mortem diagenesis in bone mineral abstract the soluble and exchangeable ions for a soil profile from the roonka archaeological site lower murray basin south australia are compared with the total elemental content of the soils since the chemical composition of post mortem ionic substitution phases and secondary minerals in archaeological bone will depend on the availability of ions to the soil solution under field conditions it is suggested that models addressing diagenesis in bone employ soluble and exchangeable ions rather than total elemental soil data

the environment of deposition indicated by the distribution of rare earth elements in fossil bones from olduvai gorge tanzania fossil bones of pleistocene age from olduvai gorge tanzania incorporated relatively high concentrations up to several thousands ppm of rare earth elements during their fossilization the data indicate that these elements were mobile during the diagenetic processes involved in the fossilization of the bones it is suggested that the high concentrations arose through interaction of the bone with groundwaters enriched in these and other elements introduced by contemporaneous carbonatitic or alkalic volcanism the distributions of the rare earth elements within both the fossil bone and enclosing sediment are heterogeneous but spatially systematic with concentration profiles showing a maximum in the bone at its sediment interface despite the relative porous nature of bone the steepness and variability of the rare earth element profiles indicate chemical equilibrium has not been reached of the individual rare earth elements ce behaved differently from the others systematic variations in and magnitudes of the ce anomaly within the bone cortices from different depositional environments indicate that the redox potential of the environment during fossilization was the principal factor affecting the distribution of this element

spatial variation of biologically available strontium isotopes 87sr 86sr in an archipelagic setting a case study from the caribbean this paper presents the results of strontium sr isotope analysis of modern and archaeological animal remains and modern plant samples from the caribbean region the goal is to assess if patterns of human mobility can be determined from the archaeological record in an archipelagic setting the range of variability and spatial distribution of biologically available strontium isotope signatures is reported and data evaluated to determine if sufficient heterogeneity exists to permit the identification of mobility despite the presence of potentially large contributions of marine strontium in island and coastal ecosystems the is landscape is divided into several sub regions based on the age and lithology of underlying geology and the variability of

physical removal of contaminative inorganic material from buried human bone abstract introduction of inorganic contaminants to bone during burial poses a serious problem for the interpretaion of the levels of these elements in terms of ancient diet we have found that the problem of non uniform contamination may be reduced or even eliminated for some elements by removal of 1 3 mm of the surface of the bone by physical abrasion whereas surface contamination on unabraded bone is readily visible in human femurs by scanning electron microscopy sem there is no evidence for contamination according to sem after abrasion this process of surface removal significantly reduces the levels of zn cd k al fe and mn but has no effect on na ca mg sr and ba for these woodland and mississippian samples from west central illinois the latter group of elements apparently survived burial without significant contamination the former group of elements was contaminated by the soil environment but at least for zn cd k and possibly fe surface removal has returned the elemental proportions in the remainder of the bone to close to biogenic levels analysis of variance between subgroups after cleaning shows differences in zn and cu between sexes in ca mg and sr over time and in na and ba based on age at death

introducing δ88 86sr analysis in archaeology a demonstration of the utility of strontium isotope fractionation in paleodietary studies abstract isotopic methods are widely used in archaeology to investigate paleodiet here we present a new method to identify trophic level in archaeological human populations and to investigate paleodiet we demonstrate that strontium isotope compositions reported as 88 86sr vary in a mass dependent manner with increasing trophic level and can elucidate paleodiet in archaeological human populations we present new mass dependent strontium isotope data from tooth enamel and bone from individuals buried during the late intermediate period c ad 1000 1300 in the large cemeteries of chiribaya alta chiribaya baja san geronimo and el yaral in the ilo and moquegua valleys of southern peru we compare these data to radiogenic strontium isotope data 87sr 86sr and light stable isotope data 15ncol and 13ccol from the same individuals to investigate geologic variability in strontium sources as well as marine food consumption among the chiribaya our results demonstrate the utility of measurements of strontium isotope fractionation as a new tool for archaeological investigation of paleodiet importantly this new technique can be used to generate paleodietary 88 86sr and paleomobility 87sr 86sr data from the same specimen minimizing destructive analyses of invaluable archaeological material and provides a new way to examine paleodiet through hydroxyapatite which is particularly important when collagen is poorly preserved

effects of diagenesis on strontium carbon nitrogen and oxygen concentration and isotopic composition of bone abstract paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured values reflect in vivo values to test for postmortem alteration we measured 87 sr 86 sr 13 c 12 c 18 o 16 o and 15 n 14 n ratios and sr concentrations in modern and prehistoric 610 to 5470 yr old bones of animals with marine or terrestrial diets from greenland bones from modern terrestrial feeders have substantially lower sr concentrations and more radiogenic 87 sr 86 sr ratios than those from modern marine feeders this contrast was not preserved in the prehistoric samples which showed almost complete overlap for both sr concentration and isotopic composition in bones from the two types of animals leaching experiments x ray diffraction analysis and infrared spectroscopy indicate that alteration of the sr concentration and isotopic composition in prehistoric bone probably results from nearly complete exchange with groundwater oxygen isotope ratios in fossil apatite carbonate also failed to preserve the original discrimination between modern terrestrial and marine feeders the c isotope ratio of apatite carbonate did not discriminate between animals with marine or terrestrial diets in the modern samples even so the ranges of apatite 13 c values in prehistoric bone are more scattered than in modern samples for both groups suggesting alteration had occurred 13 c and 15 n values of collagen in modern bone are distinctly different for the two feeding types and this distinction is preserved in most of the prehistoric samples our results suggest that postmortem alteration of dietary tracers in the inorganic phases of bone may be a problem at all archaeological sites and must be evaluated in each case while collagen analyzed in this study was resistant to alteration evaluation of the possibility of diagenetic alteration of its isotopic composition in bones from other contexts is also warranted

the huldremose iron age textiles denmark an attempt to define their provenance applying the strontium isotope system abstract archaeological textiles recovered on two occasions from the huldremose bog denmark represent some of the best preserved and complete garments from the danish iron age 500 bc ad 800 in order to address the question regarding the provenance of the textile s raw material we applied a recently developed method based on strontium isotopes to wool and plant fibres from these ancient garments textile plant fibres from huldremose i find are of non local provenance whereas the wool from which the garment was made stemmed from sheep grazing on glaciomoraine soils developed on cretaceous tertiary carbonate platform sediments widely found in denmark the huldremose ii find consists of an unusually large and well preserved garment which is composed of wool from at least three different provenances one source is again local whereas the other two sources characterized by elevated 87sr 86sr ratios are compatible with geologically older precambrian terrains which are typical for northern scandinavia e g norway or sweden our study suggests that wool and plant fibres were either traded or brought as raw materials for textiles more commonly and over longer distances than previously assumed

solubility profiles of synthetic apatites and of modern and fossil bones abstract strontium has been shown to vary within trophic levels in natural foodwebs so that previous criteria used to identify biogenic strontium in fossils namely consistent differences between herbivores and carnivores may be inappropriate in this article two alternative approaches are explored these include first experimental studies of the behaviour of synthetic apatites in the solubility profile system and second solubility profile studies of fossils from the pleistocene site of swartkrans the synthetic apatite studies show that simple mixtures of apatites dissolve discretely in the system study of swartkrans specimens reveals that while diagenetic sr is clearly present some recoverable sr varies in a manner similar to that seen in modern african foodwebs and is therefore unlikely to be of diagenetic origin

recent volcanism in the puyehue cordon caulle region southern andes chile 40 5 s petrogenesis of evolved lavas

strike slip faults and k alkaline volcanism at el chichon volcano southeastern mexico abstract el chichon volcano is located in the northern part of the state of chiapas in southeastern mexico the volcano is situated within the transcurrent fault province characterized by a series of rising and sinking blocks bounded by sinistral strike slip faults the basement around el chichon is a sequence of jurassic evaporates cretaceous limestones and tertiary terrigenous rocks folded into open and an echelon structures the main structures in the area are the la union and caimba anticlines and the buena vista syncline the region is cross cut by two conjugate fault systems a dextral strike slip n s trending set and a sinistral strike slip e w set the most significant fault of the latter system is the san juan fault which controlled the emplacement of a basaltic dike near the village of chapultenango some 1 1 ma ago and the activity of el chichon during the last 0 2 ma additionally a series of n45 e trending faults chapultengo fault system have produced a half graben geometry of blocks on top of which el chichon has been emplaced microstructures such as slickensides tension fractures layer parallel slip stylolites and macro and meso folds of the sedimentary rocks indicate that during the late miocene the el chichon area was affected by a maximum principal stress 1 oriented n70 e a minimum principal stress 3 oriented n20 w and a vertical intermediate principal stress this stress pattern indicates that the area underwent a strike slip motion that produced widespread deformation the occurrence of crustal earthquakes

mantle and slab contributions in arc magmas destructive plate margins are major sites of terrestrial magmatism that have long had a key role in models for the generation of continental crust and the development of chemical heterogeneities in the upper mantle in these models it is important to evaluate the nature and size of contributions from preexisting crust in the generation of magmas above subduction zones and to constrain the size of the fluxes of different elements from the subducted crust and the overlying mantle wedge in arc magmas kay 1 980 hawkesworth ellam 1 989 hawkesworth et al 1 99 1 a mcculloch gamble 1 99 1 the more mobile components of the subducted oceanic crust are the products of element fractionation processes in the upper continental crust the ocean basins and hydrothermal systems on the ocean floor they therefore have distinctive isotope and even trace element ratios that in principle should be readily distinguished from those in peridotite in the mantle wedge prior to subduction in practice however element ratios are almost certainly fractionated during shallow level dehydration of sub ducted material and at greater depths where material from the slab appears to contribute in the generation of arc magmas moreover the isotope signal of slab derived material may be heavily diluted by exchange with

a test of diet versus diagenesis at ventana cave arizona abstract eighty two faunal specimens from three stratigraphic levels at ventana cave arizona were analysed for multiple trace elements to investigate the effectiveness of sr and ba as dietary indicators and to assess the extent of diagenetic contamination focusing on predator prey relationships within levels comparisons with modern sonoran desert fauna and elemental correlations the results suggest that ba is a more sensitive paleodietary indicator than sr in a desert environment and that the extent of sr diagenesis is more pronounced than ba through time at the site variations in other elements such as al ca fe mg mn na and p are considered as well

tectonic interpretation of the trans mexican volcanic belt discussion discussion sur l article de shurbet d h et cebull s e paru dans tectonophysics nld 1984 101 159 165

the forced annual reversal of the atlantic north equatorial countercurrent abstract we analyze the variability of the thermal structure associated with the atlantic north equatorial countercurrent necc and its relation to the seasonally varying winds the analysis performed allows us to establish the period of time and the region where the necc reverses direction west of 25 w the depth of the thermocline in the southern side of the necc 4 to 7 n annually oscillates 180 out of phase to the oscillations on the northern side 7 to 10 n east of 25 w the thermocline rises and falls nearly in phase across the countercurrent if the flow can be uniquely presumed from the thermal structure the necc disappears during the boreal spring in the western basin the reversal of phase from north to south over one part of the ocean but no the other is shown to be mirrored in the annual variation of the curl of the stress induced at the surface by the winds in order to quantify this result the different terms of the vorticity equation are calculated from the data we conclude that t

stress distribution and subduction of aseismic ridges in the middle america subduction zone the regional distribution of stresses associated with the subduction of the cocos plate is inferred from a synthesis of 190 earthquake focal mechanisms body and surface wave analyses of large earthquakes and seismicity distributions broad patterns of consistent behavior are found across the region from the rivera plate boundary in the northwest to the guatemala el salvador border in the southeast and are used as a framework to evaluate evidence for variations in local stresses due to the subduction of two aseismic ridges the tehuantepec ridge and the orozco fracture zone information which bears on the seismic potential at locations of aseismic ridge subduction is particularly important in that no large ms 7 5 earthquakes have occurred historically we identify three major zones with consistent patterns in focal mechanisms and hypocentral distributions of seismicity the first closest to the trench and reflecting the mechanical interaction of the converging plates is a zone of shallow thrust earthquakes extending 100 150 km inland from the trench the second is a zone of normal faulting beginning at about 200 km inland from the trench h 60 km which extends continuously along the entire length of the descending plate throughout the region the third distinct zone exhibits a relatively low level of activity and separates the zones of thrust and normal faulting at about 150 200 km inland from the trench this zone extends from the rivera plate boundary in the northwest to the guatamala region in the southeast at this point the quiet region pinches out and the thrust and normal faulting zones abut and overlap superimposed on this overall pattern we find locally only minor changes in areas of aseismic ridge subduction aside from the prominent seismic slip gaps furthermore on october 25 1981 the playa azul earthquake ms 7 3 occurred in the midregion of the orozco fracture zone body and surface wave analyses of this event show a simple source rupture and shallow thrust fault mechanism as are found elsewhere in the region the seismic moment is mo 1 3 1020 n m the calculated stress drop is 4 5 mpa not extraordinarily high as might be expected in these pervasive seismic gaps an event in the tehuantepec ridge region on january 24 1983 ms 6 7 was a large normal faulting event but further interpretation is ambiguous due to the proximity of other normal faulting we conclude that while aseismic slip may be occurring in the areas of ridge subduction the possibility of large thrust earthquakes cannot be ruled out due to the overall similarities with adjacent regions

the analytical nexus of ceramic paste composition studies a comparison of naa la icp ms and petrography in the prehispanic basin of mexico ceramic compositional analyses have become a common part of archaeological inference with a multitude of techniques available which provide the best opportunity to answer specific research questions i define an analytical nexus of techniques to help archaeologists determine which techniques provide the most appropriate methodology for their study regions the relation among bulk chemical naa spot chemical la icp ms and in situ mineral petrography analyses are explored through ceramics sampled from different time periods across the basin of mexico spatial and temporal patterns of compositional variability are identified with respect to the cultural systems living there while different questions require different techniques a stable bulk signature like that provided by naa acts as a closed system that sums to 100 percent of all cultural and natural variables affecting paste composition by comparison to the bulk baseline any other technique that focuses on a fraction of the whole will also provide information on the unknown fractions

contemporaneous calc alkaline and alkaline volcanism at sanganguey volcano nayarit mexico sanganguey volcano located in the northwestern segment of the mexican volcanic belt is a calc alkaline stratovolcano that has erupted a chemically continuous suite of andesites and dacites during the past 200 000 yr alkalic volcanism however appears to have been predominant in the area since the pliocene alkalic basalts and their derivatives erupted along extensional fractures trending northwest through sanganguey and continued to erupt through the flanks of the stratocone following cessation of calc alkaline activity the calc alkaline andesite dacite volcanism was focused beneath sanganguey and appears to have been controlled by crystal fractionation in a shallow magma chamber no basalts that erupted in the area have chemical compositions that could be parental to the sanganguey calc alkaline suite the most basic calc alkaline rocks basaltic andesites have incompatible trace element concentrations nearly identical to the most basic alkaline rocks implying that the two suites were derived from distinct parental magmas alternatively it is suggested that stagnation of mantle derived alkalic basalts provided heat input to mobilize lower crustal rocks resulting in the generation of calc alkaline magmas

re and os concentrations in arc basalts the roles of volatility and source region fo2 variations olivine and spinel compositions major elements including ferric and ferrous iron s re and os contents have been measured for a suite of primitive most 6 wt mgo basalts from the trans mexican volcanic belt tmvb including the western mexican volcanic belt the michoacan guanajuato volcanic field sierra chichinautzin pico de orizaba region palma sola san martin tuxtlas and the eastern alkaline province eap sulfur contents at sulfide saturation were calculated to determine whether the measured s contents are representative of sulfide saturated liquids most of the samples have s contents much lower than expected for sulfide saturation a few have higher contents than calculated perhaps due to the presence of sulfate in the measured total sulfur i e more oxidized samples comparison of the tmvb samples along with previously analyzed morb oib babb and arc samples reveals a continuum of re and os contents that is best explained by variation in oxygen fugacity and thus sulfide stability in the source region high re and os magmatic suites are best explained by derivation by melting of oxidized mantle where sulfide is no longer stable and re and os behave incompatibly whereas low re and os magmatic suites are derived from melting of relatively reduced mantle where sulfide is stable and re and os behave compatibly intermediate examples abound and arc magmas span a wide range of re and os concentrations due to variation of fo2 in the source during genesis of arc magmas low re magmatic suites are furthermore potentially affected by volatility which can lower re by a factor of 3 5

in vitro diagenesis of teeth of sus scrofa mammalia suidae micro and nanostructural alterations and experimental dissolution abstract molars and premolars of sus scrofa were extracted and crushed to expose fresh surfaces of enamel and dentine fragments of teeth were placed in a soluble humus extract for 2 months soil composition was analysed by ion exchange chromatography and icp oes micro and nanostructural changes of the fresh and etched dentine and enamel were observed with scanning electron and atomic force microscopes extracts of soils contained dissolved organic compounds oxalic and acetic acids and humic compounds with the sugar content being low the comparison of micro and nanostructures of fresh and etched teeth shows no secondary deposits on the etched teeth the microstructures of enamel and dentine are preserved but they are smoothed enamel crystallites of etched teeth are very clean with well defined outlines two dissolution steps are observed for p and ca an unexpected result is that enamel is etched in a short time however the etching effects of the individual components present in the soil are not known thus interpreting the obtained data in a multi component solution such as soil extracts is not easy

patterns of chemical change during bone fossilization the uptake of elements by bone during fossilization is a well recognized phenomenon but the nature of and the factors leading to chemical heterogeneity in fossil bone are only just starting to be elucidated indeed in the recent past the assumption that fossil bone is chemically homogeneous has been commonly used in several investigations including those of bone dating and dietary studies in an attempt to understand the processes of element uptake we have investigated some chemical heterogeneities in a fossil bone and have assessed the potential use of bone composition as an indicator of the trace element contents of associated groundwater our study extends other work1 2 by giving the first analysis of rare earth element ree distribution in a fossil bone and by showing that information on the redox state and ree abundance pattern of the groundwater can be obtained the results contribute to the interpretation of bone analyses in studies on provenance and age determination as well as in the diet and health of past populations

geology and k ar dating of the tuxtla volcanic field veracruz mexico the tuxtla volcanic field tvf is located on the coast of the gulf of mexico in the southern part of the state of veracruz mexico volcanism began about 7 my ago in the late miocene and continued to recent times with historical eruptions in ad 1664 and 1793 the oldest rocks occur as highly eroded remnants of lava flows in the area surrounding the historically active cone of san martin tuxtla between about 3 and 1 my ago four large composite volcanoes were built in the eastern part of the area rocks from these structures are hydrothermally altered and covered with lateritic soils and their northern slopes show extensive erosional dissection that has widened preexisting craters to form erosional calderas the eastern volcanoes are composed of alkali basalts hawaiites mugearites and benmoreites with less common calc alkaline basaltic andesites and andesites in the western part of the area san martin tuxtla volcano and its over 250 satellite cinder cones and maars produced about 120 km3 of lava over the last 0 8 my a ridge of flank cinder cones blocked drainage to the north to form laguna catemaco lavas erupted from san martin and its flank vents are restricted to compositions between basanite and alkali basalt the alignment of major volcanoes and flank vents along a n55 w trend suggests an extensional stress field in the crust with a minimum compressional stress orientation of n35 e in total about 800 km3 of lava has been erupted in the tvf in the last 7 my this gives a magma output rate of about 0 1 km3 1000 year a value smaller than most composite cones but similar to cinder cone fields that occur in central mexico individual eruptions over the last 5000 years had volumes on the order of 0 1km3 with average recurrence intervals of 600 years the alkaline compositions of the tvf lavas contrast markedly with the calc alkaline compositions erupted in the subduction related mexican volcanic belt to the west leading previous workers to suggest that the tvf is not related to subduction trace element signatures of tvf lavas indicate however that they are probably related to subduction we suggest that the alkaline character of the tvf lavas is the result of low degrees of melting of a mantle source coupled with a stress regime that allows these small volume melts to reach the surface in the tvf

a census of north brazil current rings observed from topex poseidon altimetry 1992 1998 six years of topex poseidon altimeter data are used to investigate the formation of rings and eddies shed by the north brazil current upper layer thickness maps were used to identify 34 of these features formed in the north brazil current retroflection region an average of more than 5 rings and eddies per year the ensemble of ring trajectories closely parallels the 500 m isobath and one out of six rings penetrate into the caribbean sea through the southern lesser antilles the rest of the rings and eddies follow a northern trajectory past barbados once they reach 58w their estimated mean translation speed is 14 km day and their mean length scale is approximately 100 km our results suggest that the formation rate of nbc rings and eddies is nearly twice that previously thought and that they may account for more than 1 3 of the interhemispheric transport within the atlantic meridional overturning cell

geochemical study of vertebrate fossils from the upper cretaceous santonian csehbanya formation hungary evidence for a freshwater habitat of mosasaurs and pycnodont fish abstract the diverse vertebrate remains from the upper cretaceous freshwater settings at iharkut hungary contain two fossil groups pycnodontiformes fish and mosasauridae that are almost exclusively known from marine palaeo environments hence their appearance in alluvial sediments is very unusual trace element and isotope compositions of the remains have been analyzed to investigate the taphonomy and the ecological differences among the different fossil groups present at iharkut all examined fossils have undergone post depositional diagenetic alteration which resulted in high concentrations of ree u and fe together with almost complete homogenization of 18oco3 values similar ree patterns in different fossils suggest a common origin for all remains hence the discovered species most likely lived in the same local ecosystem despite partial diagenetic overprinting the 18opo4 values of the fossils indicate sufficient taxon specific isotopic diversity to permit some broad conclusions on the palaeo environment of the fossils in particular it is apparent that the isotopic composition of the pycnodontiformes fish and mosasauridae remains is most compatible with a freshwater palaeo habitat and incompatible with a marine palaeo environment in addition the sr concentration and isotope data indicate that the pycnodontiformes and mosasauridae likely lived predominantly in a freshwater environment and were not simply occasional visitors to the iharkut river ecosystem regarding other fossil groups high 18opo4 values of alligatoroidea and iharkutosuchus teeth suggest that these small crocodile species might have inhabited swamps and ponds where the water was relatively rich in 18o due to evaporation

the mean and annual cycle of upper layer temperature fields in relation to sverdrup dynamics within the gyres of the atlantic ocean using 28 years of expendable bathythermograph data 1967 1994 we describe the mean and annual cycle of the upper ocean temperature fields in the atlantic from 30 s to 50 n in the context of the basin scale wind driven gyres sverdrup stream function field which provide a framework for describing the oceanographic measurements we examine the circulation field implied by the temperature distributions which are used as a proxy for the field of mass similarities between the temperature and stream function fields increase with depth in the lower to subthermocline depths of the tropical and equatorial gyres the zonal currents form a closed circulation a southeastward boundary current is suggested near and below 150 m that provides closure for the tropical gyre and the equatorial gyre axis is southward of that suggested by the stream function field higher in the water column the north equatorial countercurrent necc may be a surface manifestation of the north equatorial undercurrent neuc where the latter can be interpreted as the southern limb of the tropical gyre because there are large vertical shears in the tropics the equatorial gyre is not clearly indicated in the vertically integrated temperature field but appears below about 200 m here the south equatorial undercurrent seuc can be interpreted as the eastward flowing northern limb of the equatorial gyre and is opposite in direction to the westward flowing south equatorial current above both the neuc and seuc are analagous to currents in the pacific that are governed by non sverdrup dynamics despite the shortcomings of the data the mean annual cycle appears to be relatively stable and we have discounted the possibility that in regions where it represents a significant percentage of the total variance it is changing slowly over the 28 years of record the wind forcing fields which undergo large meridional movements 5 6 of latitude during their annual cycle with some exceptions have essentially no counterpart in gyre movements between their seasonal extremes most of the variability associated with the annual cycle is confined to the upper 300 m greatest variability where ranges exceed 6 c occurs in the northwestern atlantic in late winter and early spring during this time of year south of the gulf stream and below about 100 m water temperatures exhibit a systematic phase lag with depth the next largest area of variability where ranges can also exceed 6 c resides in the tropical western basin between the equator and 10 n just below 100 m in the eastern basin ranges decrease and shoal additionally the phase fields are consistent with the intensification and relaxation of the tropical ridge trough system where the necc disappears in march in the west but the necc neuc complex is strongest in september

migration and viking dublin paleomobility and paleodiet through isotopic analyses abstract during the early medieval period in ireland dublin was established as the largest viking settlement on the island in the ninth century ad a previous biodistance study has suggested that the population of the town consisted of a polyethnic amalgam of immigrant and indigenous in this study we use biogeochemistry to investigate paleomobility and paleodiet in archeological human remains from the ninth to eleventh century levels at the sites at fishamble street ii national museum of ireland excavation number e172 fishamble street iii e190 and john s lane e173 as well as twelfth century remains from wood quay e132 through radiogenic strontium isotope stable oxygen carbon and nitrogen isotope and elemental concentration analyses we investigate the origins of the individuals who lived and died in early and late viking dublin mean archaeological human enamel and bone isotope values from dublin are 87 sr 86 sr 0 70975 0 00139 2 n 22 13 c carbonate v pdb 14 8 0 8 1 n 12 and 18 o carbonate v pdb 7 2 1 0 1 n 12 archaeological human bone samples exhibit mean 13 c collagen v pdb 20 8 0 5 1 n 12 and mean 15 n collagen air 10 0 1 7 1 n 12 comparing these data with archaeological faunal data from dublin and published data from northern europe we argue that there are no clear immigrants from other parts of the north atlantic although there is one clear outlier in both origins and diet overall the relative homogeneity in both paleomobility and paleodiet may support models of acculturation in viking dublin rather than a high number of first generation immigrants or continued migration from scandinavia

diagenesis in prehistoric bone problems and solutions abstract post depositional chemical alteration or diagenesis in prehistoric human bone is the major problem in the use of trace element analyses for dietary reconstruction following a review of recent studies of diagenesis we discuss means for evaluating post depositional chemical change in bone and for removing such contaminants three different procedures are described which reflect current efforts to evaluate and reduce the effects of diagenesis these include 1 mechanical cleaning 2 chemical cleaning through acid washing and 3 washing with a reducing agent these procedures usually remove major contaminants leaving significant potential of trace element analyses for the investigation of past diet

chemical compositional changes in archaeological human bones due to diagenesis type of bone vs soil environment abstract diagenesis in human remains is a subject of growing interest due to the increase in bone chemical studies to reconstruct pre and post mortem features in archaeological and forensic sciences the efforts made during the last decades have solidified our understanding of diagenetic processes however their high complexity demands more research to address them empirically specifically considering factors such as types of soil substratum and skeletal element in this work a geochemical study of human remains from the archaeological site of a lanzada nw spain is performed to understand diagenesis i e chemical alteration and life environmental exposure three types of bone thoracic long and cranial from 30 skeletons of two periods 9 roman 21 post roman were analysed by x ray fluorescence bones were recovered from burials located in slightly alkaline haplic arenosol calcaric and acidic cambic umbrisol humic soils principal components analysis was applied to extract the main chemical signatures and analysis of variance to determine the influence of different factors bone composition was characterized by four chemical signals related to i alteration of bone bioapatite ii metal sorption from the soil solution iii presence of fine silt clay soil particles and iv lead incorporation thoracic bones were found to be more sensitive to diagenesis and the burial environment long bones and crania presented a similar response skeletons buried in the acidic soil were significantly poorly preserved lead content was higher in bones of the roman period which seems to be related to pre mortem conditions previous investigations on palaeopollution in nw spain enable us to hypothesize that roman individuals may have been subjected to a high exposure of pb due to elevated atmospheric metal contamination

isotopic and trace element constraints on the origin and evolution of alkaline and calc alkaline magmas in the northwestern mexican volcanic belt a wide variety of rock types has been produced by pliocene to recent volcanism in the northwestern portion of the mexican volcanic belt composite cones erupted rocks typical of calc alkaline volcanic belts associated with subduction monogenetic cinder cones surrounding the composite cones erupted mildly alkaline basalts and related rocks one larger center las navajas produced basalts trachytes and peralkaline rhyolites such alkaline rocks are typically associated with crustal extension related to rifting both subduction and rifting appear to be taking place in western mexico the most basic calc alkaline rocks although somewhat fractionated show depletion in high field strength elements hfse and enrichment in alkaline earth elements relative to other incompatible elements a characteristic typical of magmas in subduction related volcanic arcs the basic alkaline rocks show no depletion in hfse and show higher concentrations of incompatible elements than the basic calc alkaline rocks the calc alkaline rocks show a tight cluster of 87sr 86sr and 143nd 144nd ratios both of which correlate weakly with sio2 basic alkaline rocks have lower sr and higher nd isotopic ratios whereas the more differentiated alkaline rocks have isotopic ratios that overlap with and extend beyond the range of values found in calc alkaline rocks trace element data indicate that calc alkaline magmas could not have been derived by crystal fractionation from the alkaline magmas nor by assimilation of crustal materials by alkaline magmas the evolution of both calc alkaline and alkaline rocks requires a process of crystal fractionation accompanied by assimilation afc of crustal rocks to account for changes in isotopic ratios and trace element concentrations in the more differentiated members of each suite assuming a contaminant located in the lower or middle crust afc modeling shows that the amounts of assimilation required for alkaline magmas are somewhat higher than those for calc alkaline magmas calc alkaline and alkaline rocks appear to have resulted from melting of two distinct sources alkaline from an oib type source and calc alkaline from a mixed mantle and slab derived source

radiogenic and stable strontium isotopes in provenance studies a review and first results on archaeological wood from shipwrecks abstract different approaches are used to study wood provenance but most of them are based on tracers in wood that are generally controlled by climatic factors the strontium isotopic ratio 87 sr 86 sr in trees and soils is related to the signature of the local bedrock despite being used in diverse archaeological studies sr isotopes have rarely been used to trace the provenance of archaeological wood and especially wood from shipwrecks in addition recent analytical advances have allowed the detection of mass dependent fractionation of sr isotopes during biogeochemical processes as reflected in the variation of 88 86 sr values between different environmental materials the 88 86 sr values could be used in conjunction with the 87 sr 86 sr isotope ratio to improve constraints on the sources of sr in the archaeological materials being studied this paper discusses the potential and limitations of using both of these sr isotope ratios to trace the provenance of wood from shipwrecks we review the 87 sr 86 sr and 88 86 sr variations in rocks waters soils plants and other living organisms and discuss how to determine the local sr isotopic signature of potential sites we also compile a list of known wood post mortem modifications in seawater possible implications in terms of the modification of the original sr isotope ratios of wood during storage in seawater are illustrated through preliminary observations this paper points out some limitations and perspectives for using sr isotopes in provenancing wood from shipwrecks and suggests future research to test and apply this approach for tracing the origin of archaeological wood

trace element and isotopic aspects of predator prey relationships in terrestrial foodwebs abstract strontium calcium ratio sr ca and stable carbon isotope ratio 13c 12c analyses of bone and enamel apatites may be used for reconstructing predator prey relationships in vertebrate fossil assemblages the approach is based on the rationale that 13c 12c in predator apatite closely resemble those of their prey while sr ca is predictably reduced in specific predator prey pairs as an example we compare the relationship of the extant leopard panthera pardus and its preferred prey in modern foodwebs with the relationship of fossil leopards from the member 1 fossil faunal assemblage at swartkrans cave and their likely prey the results suggest that swartkrans member i leopards depended heavily on papio baboons with some lesser contribution from hyrax procavia sp the approach has considerable potential for elucidating the preferred prey of extinct predators such as sabertooth cats

diet and mobility in middle archaic florida stable isotopic and faunal evidence from the harris creek archaeological site 8vo24 tick island abstract we explore diet and mobility in middle archaic florida using human burials and faunal remains from the harris creek archaeological site 8vo24 on tick island we conducted stable carbon and oxygen isotopic 13 c 18 o analyses of 50 human enamel samples and strontium isotopic 87 sr 86 sr analysis of a subset of 10 most individuals 46 50 subsisted on local freshwater and terrestrial resources with relatively depleted 13 c values c 3 and 18 o values matching those of central and north florida water resources within the st johns river valley eight of 10 burials have local within valley 87 sr 86 sr values two human burials yield marine 13 c and 87 sr 86 sr values which we interpret as evidence for across valley movement from the coast another two individuals show depleted 18 o values likely obtained from northern rivers we also identified potential food resources and non local foods from the harris creek faunal assemblage we found six species with estuarine and marine habitat preferences two of which whelk and quahog indicate that people of harris creek traveled to or traded with coastal areas

eddies in the north brazil current retroflection region observed by geosat altimetry mesoscale fluctuations in the western tropical atlantic are analyzed in geosat altimetry sea surface height ssh and geostrophic velocity anomalies to investigate the role of eddies in the north brazil current nbc retroflection zone the detachment of anticyclonic eddies from the nbc retroflection is observed during november through january when the nbc retroflection into the north equatorial countercurrent necc weakens and finally breaks down these eddies are traced over more than 2 months between 50 and 60 w on their way toward the caribbean at average speeds of 15 cm s 1 in one case an apparent merger of two anticyclonic eddies occurs one detached from the retroflection zone and one detached from the necc cyclonic eddies are also observed but are generally less persistent mesoscale ssh variance just west of the retroflection increases by a factor of 2 from early summer to winter mainly because of the anticyclonic eddies interhemispheric water mass transfer associated with the eddy flux out of the nbc retroflection may amount to an average transport of 3 sv

the origin of the juch uypampa cave mummies strontium isotope analysis of archaeological human remains from bolivia previous analyses of strontium isotopes from human bone and teeth have identified diverse patterns of residential mobility in the south central andes during the middle horizon ad 500e1100 during this time the large polity of tiwanaku exerted great influence over what are now southern peru northern chile northwestern argentina and bolivia recently five naturallymummified individuals were discovered in the cave of juch uypampa in the pulacayo region of southern bolivia although these individuals were buried with a number of fine tiwanaku style grave goods as well as non tiwanaku items the burial site is isolated and does not conform to the pattern of large tiwanaku affiliated cemeteries and residential sites outside of the lake titicaca basin strontium isotope analysis was performed on enamel from two adult men and bone from a third adult male in order to test the hypotheses that one or more of the males was from either the tiwanaku heartland in the lake titicaca basin the chilean oasis of san pedro de atacama which contains a series of cemeteries with tiwanaku style grave goods or the local area in which they were buried results show that two individuals likely spent their childhood in the local area where they were interred while the third man probably spent at least the last twenty years of his life in that region before being buried there this raises interesting questions regarding the nature of tiwanaku influence in southern bolivia and the relationship between the juch uypampa mummies and the tiwanaku polity 2005 elsevier ltd all rights reserved

vertical structure of the seasonal cycle in the central equatorial atlantic ocean xbt sections from 1980 to 1988 abstract a set of temperature profiles from expendable bathythermographs collected from 1980 to april 1988 along two ship routes transecting the equatorial atlantic from 11 n to 11 s is analyzed to inter the vertical structure of the annual variability of the temperature and the currents in the upper ocean during the average seasonal cycle the vertical isotherm displacements occur earlier below 300 meters than near the surface at most locations within 4 degrees of the equator at the equator the amplitude of the displacements does not decrease with depth in the upper 500 meters this still holds down to 700 meters but there are less data at these depths the lead of the deeper isotherm displacements with respect to those in the upper thermocline implies that there is a contribution to the pressure forces from these layers that is not in phase with the contribution of the upper thermocline this also suggests that the energy source of the seasonal variability is close to the surface dynamic height and

experimental constraints on the low pressure evolution of transitional and mildly alkalic basalts multisaturated liquids and coexisting augites basaltic liquids saturated at one atmosphere in augite olivine and plagioclase show a strong linear trend in pseudo quaternary projections from nepheline to slightly quartz normative compositions coexisting augites show a corresponding variation from slightly nepheline to hypersthene normative compositions consequently alkalic and mildly alkalic liquids coexist with nepheline normative augites tholeiitic liquids coexist with hypersthene normative augites and transitional liquids coexist with augites compositionally intermediate between those crystallizing in alkalic and tholeciitic melts the variation in augite composition is due to a decrease in wollastonite and non quadrilateral components going from mildly alkalic to transitional and tholeiitic augites the observed liquid and augite trends lack correlations between normative composition and crstallization temperature this is an artifact of plotting unrelated liquid lines of descent individual liquid lines of descent in contrast display good correlation between normative composition and crystllization temperature which for both liquids and coexisting augites are highly oblique to nearly perpendicular to the general trend because the composition of the first augite to appear on the liquidus varies as a function of the bulk system the location of the thermal divide shows corresponding variations as a consequence unifying cotectics and pseudo quaternary normative projections should not without specific experimental knowledge be used to address liquid lines of descent and common magmatic parentages

ecological and physiological variability of sr ca and ba ca in mammals of west european mid wurmian food webs the middle to upper paleolithic transition in western europe is characterized from an ecological point of view by large ungulate communities adapted to cold climatic conditions the aim of this study is to reconstruct the trophic relationships prevailing in these paleoecosystems which have no equivalent in the modern world bone and dentine remains representing five mammalian assemblages dated around 35 ka bp one of which included a neandertal specimen are investigated for sr ca and ba ca of bioapatites examination of the n content and u ree luminescence of bulk material ca p ratios and mn and ca contents of purified samples demonstrates that the sr ca and the ba ca ratios of bone and dentine samples are not significantly altered by diagenesis as a consequence of the biological discrimination of sr and ba in relation to ca sr ca and ba ca values are impoverished with increasing trophic position and are strongly correlated within a trophic web the slopes of the linear regressions between sr ca and ba ca are consistent with modern variability furthermore a statistical difference was found between ba ca of foregut and hindgut herbivores when coexisting collagen is preserved the sr ba ca and 15n are strongly correlated the distribution of values suggests that the 15n range is mainly controlled by the variability of soil conditions whereas the 13c range may be related to resource availability

seismicity and tectonics of the subducted cocos plate we have examined teleseismic earthquake locations reported by the international seismological centre isc for the middle america region and selected 220 as the most reliable these hypocenters and other data are used to delineate the deep structure of the subducted cocos plate the results indicate that the subducted plate consists of three major segments segment i extends from the panama fracture zone to the nicoya peninsula the structure of this segment is poorly defined segment ii is the largest and best defined segment this segment consists of two parts iia and iib part iia extends from the nicoya peninsula to western guatemala and is very well defined and continuous in structure its strike follows the curvature of the trench and dips at about 60 part iib extends from western guatemala to orizaba mexico the dip of this part of the segment decreases slightly toward the northwest and its strike is more northward than that of the trench segment iii extends from orizaba to the rivera fracture zone and is not well defined due to a lack of earthquake activity beneath about 100 km its orientation differs markedly from segment ii and strikes somewhat more westward than the trench between parts iia and iib of segment ii the subducted plate seems to be continuous bending smoothly to accommodate the change in geometry local network data from costa rica suggest there may be a tear between segments i and ii between segments ii and iii there is a gap in the hypocenters which makes it difficult to define the boundary the change in geometry between these two segments indicates that there may be a tear and two strike slip focal mechanisms in the region support this conclusion we find no convincing evidence supporting the existence of segments smaller than the three described above if there is smaller scale segmentation in the shallow part of the subducting plate the plate must still maintain enough continuity to appear continuous at greater depths there is no evidence for any major tear in the subducted plate associated directly with either the tehuantepec ridge or the orozco fracture zone the shallow subduction at the northwestern end of segment ii may be related to the bouyancy of the tehuantepec ridge the cocos ridge is probably directly responsible for the change in geometry between segments i and ii and may even be slowing or stopping subduction in segment i the structure of the subducted plate in segment ii and the changes in the character of volcanism along the arc can be related to the relative motion of the north american and caribbean plates the present geometry of part iib of segment ii is more consistent with the probable configuration of the trench about 7 ma ago than with the present configuration indicating that the north american plate is overriding the subduction zone appendices 2 3 and 4 are available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington dc 20009 document b84 009 2 50

authigenic minerals in fossil bones from the mesozoic of england poor correlation with depositional environments abstract petrographic microscopy x ray diffractometry and scanning electron microscopy energy dispersion spectrometry studies of cavity infills of bone samples from english mesozoic vertebrate deposits isle of wight swanage lyme regis aust cliff westbury garden cliff tytherington allow a better understanding of the distribution of authigenic minerals in bone voids and shed light on the importance of diagenetic processes on bone preservation surprisingly few minerals were identified as void fillers in all depositional environments carbonates sulphides oxides and sulphates being most abundant calcite is present in almost all samples pyrite is very common in voids as well as incorporated into bone francolite in many samples several generations of infills are found often consisting of layered cements the co occurrence of the common minerals indicates anaerobic slightly alkaline and often sulphate reducing environments in the bone voids later oxidation is common in iron minerals calcite pyrite and barite lack unambiguous environmental control whereas sphalerite is possibly an indicator for marine deposits freshwater deposits show no particular mineral combination which would help in separating them from other environments in some instances sediment infills and pyrite show geopetal structures

origin of archaeological black bones within a waterlogged context a multidisciplinary approach abstract this paper presents the interdisciplinary study on the origin of black bones at the neolithic lakeside settlement of dispilio greece 5500 3500 bce where animal bones have been recovered from a waterlogged and organic soil matrix containing charcoal ash and burnt cultural remains in the past this has been interpreted as the result of the destruction of the village by fire and abandonment this study aims to examine this theory through the distinction of burnt vs oxide stained bones a selection of 44 fish and 19 mammal bone samples are examined through optical microscopy scanning electron microscopy sem x ray microanalysis eds x ray diffraction xrd rietveld analysis infrared spectroscopy atr nir and chemical analyses icp ms alterations of histology mineralogy chemistry crystallinity and structural parameters prove that the black bones from dispilio owe their colour to mn and fe oxide staining light coloured bones found at the site have not been affected by this diagenetic procedure which suggests that they were buried in a totally different geochemical environment the analytical techniques employed did not offer any proof that the studied material is burnt however due to the fact that most techniques used to this day allow for the identification of thermal alteration of bone at temperatures usually higher than 300 450 c the possibility of thermal alterations due to an indirect fire thus at lower temperatures or a fire of small duration cannot be identified and thus be ruled out

metal content in medieval skeletal remains from southern croatia abstract this work is a contribution to the existing knowledge of lifestyle and diet of the south croatian population who lived in early medieval period the one hundred samples dating from 9th century were discovered and collected at the burial sites ostrovica and naklice concentrations of metals and their mutual relationships were examined in regards to gender and age of skeletal remains differences were observed in diet between men and women as well as among age groups for a correct interpretation of the results it is necessary to determine the metal content in the soil namely metals in archaeological bones are influenced by changes in soil diagenesis which is confirmed by our results we concluded that there were no influences of diagenesis on lead calcium strontium and zinc content while cadmium iron manganese and copper are most exposed

effect of atlantic meridional overturning circulation changes on tropical atlantic sea surface temperature variability a 2 layer reduced gravity ocean model study abstract previous coupled climate model simulations reveal that a dipole like sst pattern with cooler warmer temperature over the north south tropical atlantic emerges in response to a slowdown of the atlantic meridional overturning circulation amoc using a 2 layer reduced gravity ocean model a systematic investigation into oceanic processes controlling the tropical atlantic sea surface temperature sst response to amoc changes by varying the strength of northward mass transport at the open boundaries was conducted it is found that the north brazil current nbc reverses its direction in response to a shutdown of the amoc such a circulation change causes a decrease in upper equatorial ocean stratification and warming in the gulf of guinea and off the coast of africa these findings point to the importance of oceanic dynamics in the equatorial sst response to amoc changes sensitivity experiments further show that the sst response relates nonlinearly to amoc changes the strength of the sst res

a quaternary monogenetic volcanic field in the xalapa region eastern trans mexican volcanic belt geology distribution and morphology of the volcanic vents abstract the most abundant volcanic manifestations along the east west trending trans mexican volcanic belt tmvb are the scoria cones these have been grouped by other authors in extended monogenetic volcanic fields such as michoacan guanajuato chichinautzin apan and los tuxtlas here we present geological and morphological data of a relatively unknown group of monogenetic volcanoes located on the east flank of the cofre de perote volcano cp around the city of xalapa in the state of veracruz mexico within an area of about 2400 km2 the xalapa monogenetic volcanic field xmvf contains over 50 late quaternary volcanoes most of them are scoria cones but small shield volcanoes and tuff rings also occur the lava flows produced by these volcanoes are constrained by an abrupt topography and cover a great percentage of the surface on the eastern and northeastern flanks of cp between 3000 and 500 m a s l the representative rocks of the different volcanic centers include olivine basalt basaltic andesite with phenocrysts of plagioclase pyroxene and minor olivine and andesite with phenocrysts of plagioclase and pyroxene sio2 and al2o3 contents of the rocks vary between 45 and 62 wt and 15 to 18 wt respectively most of the basaltic rocks have mgo contents between 4 2 and 9 wt ni and cr concentrations between 23 and 180 and 10 to 380 ppm respectively with a typical calc alkaline behavior trace elements suggest two types of magmas the most abundant are characterized by an enrichment of lile and lree with negative anomalies of nb and ti which denote a calc alkaline affinity others are lile depleted and show high concentrations of mgo cr and ni which is typical of primary calc alkaline magmas the mean scoria cone morphological values are cone height hco 90 8 m cone diameter wco 686 38 m crater diameter wcr 208 49 m and 0 12 km3 for the cone volume we dated twelve different scoria cones using the 40ar 39ar method for the other cones we used morphologic indicators such as the ratio of the scoria cone height to basal diameter hco wco and maximum slope angle additionally vegetation type and cone and lava flow morphologies were also considered in order to determine rough relative ages in general the ages fall into three groups those older than 2 0 ma those between 0 25 0 40 ma and those less than approximately 0 1 ma

implications of diagenesis for the isotopic analysis of upper miocene large mammalian herbivore tooth enamel from chad high resolution chemical and textural investigation of upper miocene mammalian tooth enamel from chad using electron microprobe and scanning electron microscope techniques provide direct evidence of extensive diagenetic alteration when compared with some modern and contemporaneous fossil specimens chemical and textural changes in chadian fossil enamel during fossilization include large amounts of secondary fe si mn and al bearing oxides both as coarse precipitation in cracks and permeating the apatite high fluorine contamination i e apatite alteration ca p cl na and mg depletion and sulphur contamination such diagenetic contamination significantly affects the oxygen and carbon isotope analysis of carbonate in apatite altering the delta o 18 and delta c 13 biogenic signals towards more positive values isotopic alteration is however greater for oxygen than for carbon indeed isotopic analysis of the heavily oxide and s contaminated chadian fossil tooth enamel samples on a classical dual inlet multiprep system versus three continuous flow irms mass spectrometers show great differences in both the delta o 18 and delta c 13 values while the multiprep dual inlet approach provides carbon and oxygen isotopic results that are indubitably altered and generally inconsistent with any biological values isotopic analysis on continuous flow systems which automatically filter out contaminating gases allow to attain or at least greatly approach primary isotopic signals some of the chadian fossil enamel samples analysed in this work come from the very important upper miocene tm266 fossil locality that yielded sahelanthropus tchadensis a k a toumai the oldest member of the hominid clade known so far at this site as in others a few or no other environmental proxies than isotopic analysis of biomaterials are available for palaeoenvironmental and palaeoecological reconstructions therefore to obtain reliable environmental information from the time of this ancient hominid recovering uncontaminated biogenic isotopic signals is crucial and from these results it is now technically possible c 2008 elsevier b v all rights reserved

as a dietary indicator in modern and archaeological bone strontium isotope ratios 87sr86sr in human and animal bone are inherited via foodstuffs from rocks in the areas in which an individual lived if such an area includes more than one rock type with differing 87sr86sr or is coastal region with terrestrial 87sr86sr different from that of the sea then bone strontium isotope ratio measurements provide a measure of the relative importance of foods from each isotopic zone in the southwestern cape of south africa marine and coastal terrestrial areas covered by marine sands should yield foods with 87sr86sr close to the marine average while the cambrian and pre cambrian shales and sandstones of the hinterland ought to be enriched in 87sr from radioactive decay of 87rb during the considerable time elapsed since they were laid down analyses of modern animal bones show that these patterns do prevail furnishing us with a new means of reconstructing prehistoric diets preliminary measurements on archaeological human material recovered from coastal shell midden sites apparently reflect heavy reliance on coastal foods however these bones have been shown to be contaminated with diagenetic marine strontium from the shells in the middens experiments on faunal specimens show that diagenetic strontium can be removed by repeated washing in acetic acid sodium acetate buffer mineral with 87sr86sr similar to the burial environment dissolves first while subsequent washes remove strontium with different 87sr86sr for two coastal human skeletons however the marine coastal terrestrial nature of the isotopic signature remains further experimental work is required in order to establish the limits of the technique however a combination of the solubility profile method and strontium isotope analysis promises to provide a powerful tool for reconstructing palaeodiets

sr isotopic composition of hydroxyapatite from recent and fossil salmon the record of lifetime migration and diagenesis by comparing the sr isotopic composition of migratory fossil salmon which lived in the ocean but died in continental regions to the well established marine sr isotopic record the age of the continental deposit could be determined with high accuracy this approach to marine continental correlation and dating requires 1 that marine resident salmon bear a marine s7sr 86sr value in their bones or teeth and 2 that the original s7sr 86sr value of fossils is not overprinted by diagenesis the vertebrae of modern hatchery reared salmon exhibit sr isotopic variations indicative of freshwater to marine migration during bone growth modern marine s7sr s6sr values were preserved in growth layers formed later in life marine phase growth layers in the bones and teeth of the late miocene migratory salmon oncorhynchus rastrosus were subjected to stepwise selective leaching to separate biogenic hydroxyapatite from diagenetic calcium carbonate and recrystallized hydroxyapatite although the procedure yielded leachates with sr ca and ca p values characteristic of apatite the leachates had 87sr s6sr values consistently less radiogenic than values for late miocene seawater 0 7087 the fossils were substantially contaminated by sr from the hosting clastic sediments specimens in continental deposits differed in 87sr 86sr value from host sediments by 0 0002 to 0 0200 supporting the conclusion that these salmon were migrants from marine waters however because the original sr isotopic composition of fossil bones and teeth cannot be determined with confidence archaeological paleobiological and stratigraphic applications of this technique may be limited

constraints on the origin of alkaline and calc alkaline magmas from the tuxtla volcanic field veracruz mexico lavas erupted in the tuxtla volcanic field tvf over the last 7 ma include primitive basanites and alkali basalts mildly alkaline hy normative mugearites and benmoreites and calc alkaline basalts and basaltic andesites the primitive lavas are silica undersaturated with high concentrations of both incompatible and compatible trace elements variable la yb with constant yb at 6 to 8 times chondritic and low sr and o and variable pb and nd isotopic ratios the primitive magmas originated by increasing degrees of melting with pressure decreasing from greater than 30 kbar to 20 kbar in the garnet stability field another group of alkali basalts and hawaiites has lower ni and cr concentrations and higher fe mg ratios and was derived from the primitive group by crystal fractionation at pressures of several kbar incompatible trace elements in these silica undersaturated lavas show depletion in high field strength elements hfse relative to large ion lithophile elements similar to subduction related basalts ba nb ratios are nearly constant and thus the hfse depletion cannot be the result of a residual hfse bearing phase in the source but could be the result of generation from a source contaminated by fluids or melts from the subducted lithosphere the silica saturated mugearites and benmoreites and the calc alkaline basalts and basaltic andesites were erupted only between 3 3 and 1 0 ma these have incompatible element concentrations generally lower than in the silica undersaturated lavas and thus could not have been derived by crystal fractionation from the silica undersaturated alkaline magmas magmas parental to the silica saturated magmas originated by higher degrees of melting at lower pressures than the primitive magmas melting may have been promoted by an influx of fluid from the subducted lithosphere trace element and sr nd pb and o isotopic data suggest that three components are involved in the generation of tvf magmas the mantle a fluid from the subducted lithosphere and continental crust tvf alkaline lavas are similar to those erupted in the back arc region of the mvb and japan and show characteristics similar to alkaline magmas erupted in the southern andean volcanic arc these low degree melts reach the surface along with calc alkaline lavas in the tvf due to an extensional stress field that allows their passage to the surface

the forest or the trees behavioral and methodological considerations for geochemical characterization of heavily tempered ceramic pastes using naa and la icp ms abstract in this paper the utility of la icp ms for instrumentally separating clay and temper within pottery samples is examined through a well known case study that has been previously characterized through naa and petrography coarse orange pottery is composed of kaolinitic clays heavily tempered within volcanic ash from the basalt rich tuxtla mountains of southern veracruz mexico we attempt to address the following topics with analyses on this pottery 1 can la icp ms replicate the same groups previously identified by naa and petrography 2 can instrumental isolation of the clay fraction within the pottery replicate known patterns in raw clay source geochemistry in the tuxtla mountains 3 can data for both the clay and volcanic ash fractions of each pottery sherd be combined to simulate the bulk inaa data the results demonstrate that the clay fraction of the pottery sherds can be isolated furthermore the la icp ms data for the clay fractions display nearly identical chemistry to available naa data for raw clay samples collected from geological contexts in the region instrumentally isolating the clay fraction in this case eliminates the homogenizing effects of adding a common temper and increases the chemical separation among groups making it easier to identify clay procurement strategies for each specimen however focusing only on the clay fraction ignores significant tempering variation attempts to simulate the bulk naa by combining la icp ms data for clays and temper was reasonably successful in reestablishing the tempering variation lost by exclusive focus on clays but such an approach could not replace the more precise data generated from naa and petrography

correction to isotopic and trace element constraints on the origin and evolution of alkaline and calc alkaline magmas in the northwestern mexican volcanic belt by surendra p verma and stephen a nelson

differential diagenesis of strontium in archaeological human dental tissues the investigation of prehistoric human migration from the measurement of sr isotope ratios within preserved tissue is critically dependent on the preservation of biogenic sr a number of recent studies have involved isotope ratio measurements on samples of archaeological tooth and bone but doubt remains as to the extent of diagenesis in various skeletal tissues and the effectiveness of procedures designed to decontaminate them the authors have compared sr abundance and isotope ratios in enamel and dentine from archaeological teeth in order to assess the integrity of the biogenic sr signal preserved within the respective tissues it is concluded that enamel appears in most cases to be a reliable reservoir of biogenic sr but that dentine and by implication bone is not the diagenesis of dentine is highly variable even between burials within a single site for the majority of teeth dentine diagenesis was not simply by addition of soil derived sr but involved substantial sometimes complete turnover of the original biogenic material it is suggested that for most of the samples investigated current decontamination techniques may not have been effective in isolating biogenic sr from dentine similar considerations are likely to apply to archaeological and fossil bone but the possibility arises to use dentine and enamel measurements to assess the effectiveness of decontamination procedures which may then be used for bone

primitive calc alkaline and alkaline rock types from the western mexican volcanic belt since the early pliocene small volumes of alkaline magmas have erupted in the western mexican volcanic belt mvb in close association with the volumetrically dominant calc alkaline magmas both suites include relatively rare primitive types characterized by high mg cr and ni contents primitive hypersthene normative basalts parental to the calc alkaline suite are found along the volcanic front but are absent at greater distances from the trench the volcanic front calc alkaline suites are typically hornblende bearing indicating relatively high water contents associated primitive alkaline magmas at volcanic front locations also contain hydrous minerals these nepheline normative suites include basanites phlogopite bearing minettes and other hornblende bearing lamprophyres these are probably the youngest and freshest lamprophyres yet discovered on earth and ideal samples for addressing the origin of this exotic class of rocks on extended morb normalized elemental plots all lamprophyres show patterns similar to the calc alkaline basalts but have overall enrichments of 2 to 25x in ti k p ba sr light rare earth elements and other incompatible elements the lamprophyres show the same strong relative enrichments of ba k and sr and depletions in ti and nb that characterize the calc alkaline rocks of western mexico and all subduction zones these similarities in relative element abundances support a common source region for all primitive magmas of the western mvb the primitive calc alkaline and alkaline rocks of western mexico show narrow overlapping ranges in sr nd and pb isotopic ratios also consistent with derivation of all magmas from a common source the presence of the relatively cold subducted cocos and rivera plates below the volcanic front demands that all primitive magmas originated in the depth range 30 to 75 km these magmas are enriched in ba k sr and other elements probably transported by hydrous fluids rising from the subducted slab several lines of evidence support the presence of phlogopite in the source region of western mvb magmas probably in the form of phlogopite rich veins cutting asthenospheric peridotite the first liquids formed upon partial melting of this veined source region will concentrate the vein component and generate the lamprophyres these lamprophyric melts rarely erupt in arc settings more commonly forming dikes in the arc crust eruption of lamprophyric magmas in the western mvb is favored by through crustal extensional fracture systems related to active rifting of the jalisco block from the n american plate larger volumes of calc alkaline basalt are generated by melting of the same source which dilutes the vein component with larger proportions of peridotitic wall rock

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

mobility of bell beaker people revealed by strontium isotope ratios of tooth and bone a study of southern bavarian skeletal remains in order to contribute to the continuing discussion of the mobility of the late neolithic bell beaker people 69 skeletons from southern bavaria were analyzed for the 87sr 86sr isotope ratios in tooth enamel and compact bone whereas sr isotope ratios in the enamel of the first permanent molar match the sr isotopic composition at the place of early childhood the respective value in the adult femoral bone matches the sr isotope ratio characteristic of the place of residence over the last few years prior to death significant differences between 87sr 86sr in these tissues indicate that 17 5 25 of these individuals changed residence during their lifetime the overall direction of the migration according to archaeological finds from the area was toward the southwest a relative surplus of migrating females and two cases of evidence for migration in children argue for the movement of small groups exogamy might explain the higher numbers of immigrating females with regard to current information on migration rates in prehistory the southern bavarian bell beaker people were indeed highly mobile especially since the archaeometric method used in this study is likely to underestimate movement

uranium and thorium distributions in fossil bones from olduvai gorge tanzania and kanam kenya abstract the micro distributions of uranium and thorium have been studied in fossil bone cortices in samples from olduvai gorge tanzania and kanam kenya and compared with modern bones collected from the surface at olduvai gorge concentrations in excess of 800 ppm u and 200 ppm th are recorded in sections of some fossil bones whereas concentrations do not exceed 20 ppm u or 1 ppm th in the modern bones in fossil bones th has a larger intra bone variation than u the distribution profiles of the two elements across the fossil bone cortices are quite distinct and reflect differences in their geochemical behaviour in the supergene environment in particular the two possible oxidation states of u compared with one for th allow u to be more mobile than th but also more susceptible to variations in the redox potential of the depositional environment in some fossil bone samples secondary leaching of u has occurred whereas th is retained in the bone cortex u is incorporated into fossil bone earlier than th

determining the local 87sr 86sr range for archaeological skeletons a case study from neolithic europe measurement of strontium isotopes in archaeological skeletons is an effective technique for characterizing prehistoric mobility however interpretation of the results can be highly sensitive to small changes in the determined local 87sr 86sr signature at an archaeological site because the local range is often defined as within 2 s d from the mean 87sr 86sr value in archaeological human bones the susceptibility of bones to diagenesis may lead to significant overestimates in the number of non locals at a particular site tooth enamel on the other hand is highly resistant to postmortem biochemical alteration and it is found that 87sr 86sr in archaeological enamel samples from animals of neolithic germany provide a useful alternative estimate for the local range

sr and sr ca in marine and terrestrial foodwebs in the southwestern cape south africa abstract strontium and calcium have been measured in a range of plants and animals both marine and terrestrial from the southwestern cape of south africa as part of an investigation of modern and prehistoric foodwebs in the region first the meat of marine molluscs and crustaceans are shown to have sr and sr ca values comparable to those of terrestrial plants thus the consumption of these marine foods in this region cannot produce the markedly elevated sr levels seen in archaeological human skeletons from coastal sites such levels are shown to be a diagenetic phenomenon second reduction in sr ca in higher trophic levels is seen only when predators are compared with their prey however individual herbivore or carnivore species cannot be taken to represent other animals in their respective trophic level these data imply that sr ca is inappropriate for determining meat intake in complex prehistoric human diets in this region the technique may be more useful in examining specific prey predator relationships including those in the early hominid fossil record

strontium increases and crystallinity changes in taphonomic and archaeological bone bone strontium levels and hydroxyapatite crystal sizes increased with time in two exposed wildebeest skeletons the strontium increases could not be removed by sequential washing according to the method of sillen a 1986 biogenic and diagenetic srca in plio pleistocene fossils of the omo shungura formation paleobiology12 311 323 human subfossil bone recovered archaeologically also showed evidence of extensive diagenetic reworking that resulted in crystal growth and elevated strontium levels the increase in bone strontium content was independent of nonapatitic contaminating crystal phases

upper layer temperature structure of the western tropical atlantic mean monthly topographies of the 20 c and 10 c isothermal surfaces are used to describe the vertical displacements of the upper and lower thermocline in the western tropical atlantic the isotherm topographies are generated from expendable bathythermograph data collected between 1966 and 1993 the topographies confirm and extend closer to the coast earlier findings that demonstrate large spatial and temporal variability in the region for example the ridge and trough systems observed previously in the interior are shown and their extension to the western boundary is described in particular it is shown that the ridge associated with the north equatorial countercurrent necc extends from the interior northwestward along the western boundary reaching farther north along the boundary in the upper thermocline than in the lower thermocline south of the equator the northwestern corner of the countercurrent trough is apparent on the lower surface but not on the upper the annual and semiannual harmonics of the vertical isotherm displacements account on the average for about 60 of total variance on both surfaces the horizontal structure of the first harmonic amplitude is similar for both surfaces showing maximum amplitude along the axis of the necc ridge minimum amplitudes are observed to the north along the axis of the countercurrent trough these distributions are similar to the pattern of the first harmonic amplitude of the wind stress curl supporting earlier studies of curl forcing of near surface current features

impact of the choice of bone samples on trace element data in excavated human skeletons abstract the choice of bone samples for trace element analysis of excavated human skeletons is of great influence on trace element data and their interpretation with regard to the reconstruction of ancient diets and palaeoenvironment trace element content in bone specimens from different anatomical sites shows considerable variations even in a single individual primarily due to different metabolic turnover rates in compact and trabecular bone it can be shown that the trace element content in a compact bone sample is well correlated with the total skeletal content of the respective element the use of compact bone from corresponding anatomical sites for trace element analyses is therefore recommended since otherwise any comparison of trace element data of different individuals may produce misleading results

the consequences of wari contact in the nasca region during the middle horizon archaeological skeletal and isotopic evidence during the middle horizon ad 650e1000 the wari polity expanded its sphere of control in various regions of the andes including nasca on the south coast of peru the nature of the interaction between wari and local communities varied this study explores the consequences of wari contact in the nasca region at the site of la tiza which includes individuals dated to the early intermediate middle horizon and late intermediate periods using evidence for burial ritual along with demographic paleopathological and isotopic data population composition mobility diet and health are investigated d 13 c data indicate a relatively stable diet through time at la tiza with evidence for continued maize consumption and paleopathological results indicate health problems associated with this type of diet d 18 o and 87 sr 86 sr data suggest that most of the individuals buried at la tiza were local to the area however two female adults from the middle horizon burials are characterized as nonlocal based on d 18 o and 87 sr 86 sr values and several individuals overlap with the 87 sr 86 sr local range for the wari heartland in conjunction with the use of new tomb types during this period these results highlight the ideological and populational changes occurring with wari contact at la tiza