shallow system rejuvenation and magma discharge trends at piton de la fournaise volcano la reunion island basaltic magma chambers are often characterized by emptying and refilling cycles that influence their evolution in space and time and the associated eruptive activity during april 2007 the largest historical eruption of piton de la fournaise ile de la reunion france drained the shallow plumbing system 240 106 m3 and resulted in collapse of the 1 km wide summit crater following these major events piton de la fournaise entered a seven year long period of near continuous deflation interrupted in june 2014 by a new phase of significant inflation by integrating multiple datasets lava discharge rates deformation seismicity gas flux gas composition and lava chemistry we here show that the progressive migration of magma from a deeper below sea level storage zone gradually rejuvenated and pressurized the above sea level portion of the magmatic system consisting of a vertically zoned network of relatively small volume magma pockets continuous inflation provoked four small 5 106 m3 eruptions from vents located close to the summit cone and culminated during august october 2015 with a chemically zoned eruption that erupted 45 15 106 m3 of lava this two month long eruption evolved through i an initial phase of waning discharge associated to the withdrawal of differentiated magma from the shallow system into ii a month long phase of increasing lava and so2 fluxes at the effusive vent coupled with co2 enrichment of summit fumaroles and involving emission of less differentiated lavas to end with iii three short lived 2 day long pulses in lava and gas flux coupled with arrival of cumulative olivine at the surface and deflation the activity observed at piton de la fournaise in 2014 and 2015 points to a new model of shallow system rejuvenation and discharge whereby continuous magma supply causes eruptions from increasingly deeper and larger magma storage zones downward depressurization continues until unloading of the deepest least differentiated magma triggers pulses in lava and gas flux accompanied by rapid contraction of the volcano edifice that empties the main shallow reservoir and terminates the cycle such an unloading process may characterize the evolution of shallow magmatic systems at other persistently active effusive centers

exchange of carbon with biological apatite abstract the validity of using carbon isotopes in biological apatite from bone for dietary studies has been questioned because of diagenetic alterations and supposed exchange of carbon from the burial environment laboratory and natural experiments have been devised to test the integrity of carbon isotope ratios in biological apatite with respect to isotopic exchange of carbon with natural waters the laboratory experiment subjected a sample of bone to a synthetic groundwater whose carbon isotopic composition had been adjusted to 9750 analyses indicate that simple carbonates exchanged rapidly with the groundwater but that the actual biological apatite exchanged very little if any of its carbon even with 2 years exposure the natural experiment involved analysis of mammoth and mastodon teeth that had been submerged in sea water for 11 000 years with proper cleaning the original dietary signals were well preserved despite the long exposure to oceanic dissolved carbonate of much different isotopic composition these experiments suggest that properly cleaned biological apatite is an appropriate analytical phase for dietary studies on bone or teeth as old as 10 000 years

simulation of groundwater exchange between an unconfined aquifer and a discrete fracture network with laminar and turbulent flows abstract in this study a new approach is developed to simulate groundwater flow through both an overlying unconfined aquifer and an underlying discrete fracture network the groundwater exchange between the aquifer and the fracture network including magnitude and direction is explicitly simulated based on the mass conservation which depends on a variety of parameters related to flow and network characteristics in the overlying unconfined aquifer we approximate the flow using the dupuit assumptions in the underlying fracture network we use the cubic law and forchheimer s law to iteratively simulate laminar or turbulent flow in individual fractures depending on the reynolds number explicitly separating laminar and turbulent flows in the fractures results in a system of nonlinear equations which is iteratively solved while the flow from the overlying unconfined aquifer is a small portion of the overall flow in the underlying fracture network incorrect use of the laminar or turbulent flow equation in the fractures can lead to significant errors in simulating the flow exchange as apertures increase both the portion of the total flowrate in the aquifer and the portion of the flow in the fractures coming from the aquifer decrease as the overall hydraulic gradient increases both the portion of the total flow in the aquifer and the portion of the fracture flow that comes from the aquifer increase the portion of the total flow in the aquifer increases with the aquifer thickness while the portion of fracture flow coming from the overlying aquifer decreases

basaltic calderas collapse dynamics edifice deformation and variations of magma withdrawal 1 the incremental caldera collapses of fernandina 1968 miyakejima 2000 and piton de la fournaise 2007 are analyzed in order to understand the collapse dynamics in basaltic setting and the associated edifice deformation for each caldera the collapse dynamics is assessed through the evolution of the 1 time interval t between two successive collapse increments 2 amount of vertical displacement during each collapse increment and 3 magma outflow rate during the whole collapse caldera process we show from the evolution of t that piton de la fournaise and fernandina were characterized by a similar collapse dynamics despite large differences in the caldera geometry and the duration of the whole collapse caldera process this evolution significantly differs from that of miyakejima where t strongly fluctuated throughout the whole collapse process quantification of the piston vertical displacements enables us to determine the magma outflow rates between each collapse increment displacement data tiltmeter and or gps for piton de la fournaise and miyakejima are used to constrain the edifice overall deformation and the edifice deformation rates these data reveal that both volcanoes experienced edifice inflation once the piston collapsed into the magma chamber such a deformation which lasts during the first collapse increments only is interpreted as the result of larger volume of piston intruded in the magma chamber than magma withdrawn before each collapse increment once the effect of the collapsing rock column vanishes edifice deflates we also determine for each caldera the critical amount of magma evacuated before collapse initiation and compare it to analog models the significant differences between models and nature are explained by the occurrence of preexisting weak zones in nature i e the ring faults that are not taken into account in analog models finally we show that t at piton de la fournaise and fernandina was equally controlled by the frictional resistance along the ring faults and the magma outflow rate in addition to these two parameters the collapse dynamics of miyakejima was also influenced by variations of the magma bulk modulus which changed after the influx of deep gas rich magma into the collapse related magma chamber altogether our results show that the dynamics of caldera collapse in basaltic volcanoes proceeds in two phases phase 1 starting with the first collapse is characterized by the largest collapse amplitude an incremental edifice inflation and a step by step increase of the rate of magma outflow phase 2 shows a rapid decrease of the magma discharge rate to a low level concomitant with the continuous edifice deflation if deep magma is injected into the magma chamber as at miyakejima an additional phase occurs phase 3

development and application of an analytical model of stream aquifer interaction abstract a mathematical model to simulate stream aquifer interactions in an unconfined aquifer subjected to time varying river stage was developed from the linearized boussinesq equation using the principle of superposition and the concept of semigroups the mathematical model requires an estimate of three parameters to simulate ground water elevations transmissivity specific yield and recharge the solution has physical significance and includes terms for the steady state water level the steady state water level as influenced by a change in river stage a transient redistribution of water levels in the aquifer from the previous day and a transient change in water level caused by a change in river stage the mathematical model was tested using observed water table elevations at three locations across a 2 km wide alluvial valley aquifer the average absolute deviation between observed and simulated daily water levels was 0 09 m the difference in river stage over the test year was 4 9 m

la reunion island dunites as analogs of the martian chassignites tracking trapped melts with incompatible trace elements abstract fractional crystallization of basalts produces a variety of ultramafic cumulates poor in incompatible elements in order to discuss the effect of trapped liquids on the concentrations of incompatible elements in these cumulates we studied a series of dunites and pyroxenites from the piton de la fournaise la reunion island indian ocean these rocks have a high variability in the abundance of these elements which is only partially explained by their proportions of olivines and pyroxenes mass balance calculations indicate that 0 25 to 1 wt of trapped melts are required to account for the budget of the highly incompatible element abundances such as u rb nb or light rare earth elements ree using our results we revisited the ree geochemistry of chassignites a grouplet of martian meteorites chassignites are mineralogically texturally and chemically very similar to the dunites from la reunion island which can be seen as very close terrestrial analogs the variations of ree abundances and ratios in chassigny one of the three known chassignites can be explained by inhomogeneous distribution of trapped melts in this meteorite at the scale of the size of the fragments typically

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

reducing the computational cost of unconfined groundwater flow in conjunctive use models at basin scale assuming linear behaviour the case of adra campo de dalias the optimization of conjunctive use management models with different competing demands several reservoirs and aquifers and a high interconnection among elements over long time horizons requires the use of computationally efficient groundwater flow models a review of conjunctive use models and some methods applied to reduce the computational cost of the groundwater flow model has been performed with special attention to the assumption of linear behaviour the effect of considering invariant transmissivity in a conjunctive use management model at the basin scale has been analyzed using as case study the adra campo de dalias system southeast of spain the system includes an unconfined aquifer not hydraulically connected to the river in which significant drawdown relative to the saturated thickness can appear the basin scale system also includes storage in a reservoir flows in several river segments and canals and a second simpler aquifer the management formulation seeks the best conjunctive operation of reservoir and aquifer to meet urban and irrigation demands while satisfying minimum flow and aquifer head constraints over a time horizon of several years the effect of the linear assumption has been studied by comparing and analyzing management model results obtained modeling the aquifer as confined and as unconfined groundwater flow is simulated in the optimization model using the response matrix method the optimization problem is solved using sequential linear programming slp in the unconfined case and using linear programming lp when confined behaviour is assumed although the drawdown are significant the difference in results is minor suggesting that the use of a linear assumption may be valid in many basin scale conjunctive management problems in which the aquifer is not hydraulically connected to the river system nevertheless the assumption should be tested if possible in each management problem with unconfined aquifers in which significant drawdown appears

modeling transient stream aquifer interaction with the non linear boussinesq equation and its analytical solution a new analytical solution of the non linear transient groundwater flow equation subject to time variable river boundaries was used to simulate stream aquifer interactions in an alluvial valley aquifer the differential equations were solved using the method of decomposition the mathematical model required relatively few parameters to simulate groundwater elevations hydraulic conductivity specific yield and recharge the model was physically based and could simulate the process of a flood wave propagation into an unconfined aquifer the model was tested using observed water table elevations at three locations across a 2 km wide alluvial valley aquifer the average daily deviation between observed and simulated water table elevations was approximately 0 09 m the transient redistribution of water in the aquifer was simulated well with the model the non linear form of the boussinesq equation was shown to better simulate cases when the transmissivity of the aquifer could not be assumed to be a constant

stream floodwave propagation through the great bend alluvial aquifer kansas field measurements and numerical simulations abstract the hypothesis is explored that groundwater level rises in the great bend prairie aquifer of kansas are caused not only by water percolating downward through the soil but also by pressure pulses from stream flooding that propagate in a translatory motion through numerous high hydraulic diffusivity buried channels crossing the great bend prairie aquifer in an approximately west to east direction to validate this hypothesis two transects of wells in a north south and east west orientation crossing and alongside some paleochannels in the area were instrumented with water level recording devices streamflow data from all area streams were obtained from available stream gaging stations a theoretical approach was also developed to conceptualize numerically the stream aquifer processes the field data and numerical simulations provided support for the hypothesis thus observation wells located along the shoulders or in between the inferred paleochannels show little or no fluctuations and no correlations with streamflow whereas wells located along paleochannels show high water level fluctuations and good correlation with the streamflows of the stream connected to the observation site by means of the paleochannels the stream aquifer numerical simulation results demonstrate that the larger the hydraulic diffusivity of the aquifer the larger the extent of pressure pulse propagation and the faster the propagation speed the conceptual simulation results indicate that long distance propagation of stream floodwaves of the order of tens of kilometers through the great bend aquifer is indeed feasible with plausible stream and aquifer parameters the sensitivity analysis results indicate that the extent and speed of pulse propagation is more sensitive to variations of stream roughness manning s coefficient and stream channel slope than to any aquifer parameter

dynamics of floodplain island groundwater flow in the okavango delta botswana abstract surface water groundwater interactions play a crucial role in the hydrology and ecology of the okavango delta the hydrology of the delta is dominated by the annual arrival of a flood wave which is distributed over an number of branches subsequently the flood water feeds the phreatic aquifers underlying the delta islands in order to evaluate the seasonal and long term dynamics of the surface water groundwater interactions between the floodplains and the islands a network of piezometers located in various locations of the delta was monitored groundwater table fluctuations observed for up to 6 years were analysed and modelled using groundwater flow models the floodplain island groundwater flow is in general very dynamic and driven by island evaporation and transpiration a typical small to medium sized island width 500 m and at the perimeter of the flooded area is the influence of long term antecedent conditions apparent the knowledge gained during this study will be used for the improvement of the hydrological and hydro ecological model of the delta and can be useful for the description of floodplain dynamics in semi arid regions in general

reply to battaglia and cayol 2009 we thank cayol and battaglia 2009 hereafter referred to as cb2009 for commenting on our work houlie and montagner 2007 we start our response by reviewing our model and then discuss the potential of discrimination of tilt and displacement at a vbb seismometer from seismic records there appears to be a misunderstanding of the approach and the interpretation of our results presented in houlie and montagner 2007 we do not question the discovery by battaglia et al 2000 of transient deformation before volcanic eruptions as well as the existence of 2 types of signals but the interpretation is not necessarily as simple as proposed in their paper we note that the three components in the seismic record of displacement might have different explanations from a theoretical point of view any perturbation of displacement can be expressed as follows ui t j ui t xj dxj it means that ui t can be expressed by 9 independent terms since zj 0 at the surface of the earth there remain 6 degrees of freedom usually the symmetric part deformation eij related to the stress tensor in the elastic case is separated from the anti symmetric part that is related to rotation or tilt consequently distinguishing displacement and tilt is a real scientific challenge very long period period tn100 s transients are interpreted in terms of tilts battaglia et al 2000 but we explore the possibility that a large part of seismic record is related to translational displacement in addition of or rather than tilt rotation following this simple idea we draw the consequences of this hypothesis and propose a model which differs from previous approaches battaglia et al 2000 battaglia and bachelery 2003 battaglia et al 2005 there are two extreme models for interpreting the data the first one is only based on tilt associated with the dislocation model okada 1992 and a second one is based on ground displacement generated by a spherical source cb2009 claim that the whole signal can be explained by tilt but we claim that a significant part of the signal is related to ground displacement and that actual data cannot yet discriminate between these two models it is likely that both effects are present and the next challenge will be to determine where the right loci of the true solution are between these 2 extrememodels the intention of our paper houlie andmontagner 2007 was to draw attention to this fundamental issue which has important consequences for the understanding of volcano eruption dynamics we suggest that the actual data are not sufficient to provide a definitive answer to this issue our work shows that an interpretation of the currently available seismic record in terms of translational displacements is perfectly valid and that further work will be needed to discriminate between tilt and displacement models and combinations of the two

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

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

aquifer response to surface water transience in disconnected streams 1 existing analytical solutions to determine aquifer response to a change in stream stage are inappropriate where an unsaturated zone exists beneath the stream as in the case of disconnected stream aquifer systems a better understanding of the relationship between aquifer response and transient stream stage in disconnected systems is therefore required as this would also aid in the field determination of the status of connection between the stream and aquifer we use a numerical model to examine transient stream stage and the corresponding water table response beneath disconnected streams the magnitude of head change in the water table level is a balance between the cumulative infiltration during a flow event and the rate at which the water can disperse laterally increases in wave duration stream width and streambed permeability result in greater infiltrated water volume and therefore a higher peak response at the water table conversely higher aquifer transmissivity and aquifer hydraulic conductivity allow the water to move laterally away from the stream faster resulting in a smaller head change below the stream lower unsaturated storage results in a greater and faster aquifer response because the unsaturated zone can fill more quickly under some combinations of parameters the magnitude of the disconnected head response is more than seven times greater than the change in stream stage driving streambed infiltration an effect which can never occur beneath a connected stream the results of this sensitivity analysis are compared to field data from a river in eastern australia to determine periods of disconnection where the change in aquifer head is greater than the change in stream stage disconnection between the stream and aquifer can be determined

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

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

crystal structure mosaicity and strain analysis of hawaiian olivines using in situ x ray diffraction deformation of olivine in a volcanic context is poorly constrained although deformed olivine is abundant in some volcanic rocks and its presence is important for the definition of the magmatic history of volcanic edifices such as kilauea volcano hawaii deformed olivines at kilauea originate in the lower crust therefore the classic approaches and interpretations applied to mantle derived olivine are not applicable deformed olivine crystals from kilauea lava samples were examined using an in situ xrd technique our results validate and refine optical observations of olivine deformation we also confirm the presence of deformation and quantify it for olivine crystals of any size even for small crystals 0 15 mm there are significant correlations between deformation intensity strain related mosaicity and olivine composition and crystal size although this technique does not allow the simple estimation of the p t conditions of deformation crystal formation or magmatic history some constraints are provided herein in particular we estimate the threshold degree of mosaicity above which we consider that a crystal underwent deformation in situ xrd is shown to be an easy to use fast low cost non destructive technique and is less ambiguous than optical microscopy for crystals optically exhibiting subgrain formation analysis of asterism by in situ xrd has been used to reconstruct the mosaic spread of the original grain and thus its original strain condition prior to subgrain formation

aquifer response to sinusoidal or arbitrary stage of semipervious stream analytical expressions for the aquifer responses viz groundwater head rate of flow and cumulative volume of flow to a generalized sinusoidal stage of semipervious streams considering the stream boundary resistance are derived the analytical aquifer responses to a linear stream stage and to a typical analytical flood wave that was used by cooper and rorabaugh are also derived for a zero stream resistance the aquifer responses converge to those for a fully penetrating stream also two analytical methods a ramp kernel method and a fourier series method for obtaining the aquifer responses to an arbitrary temporal stage of sempervious stream are developed the analytical expressions of the ramp kernels for different aquifer responses are developed the ramp kernel method is found superior to the conventional convolution that uses numerical integration or pulse kernels for obtaining the convolution integral in the fourier series method the aquifer responses to sinusoidal stage are used along with fourier series the results obtained using both methods are in close agreement the new methods are also applicable to fully penetrating streams by assigning a zero value to the stream resistance

gravity structure of piton de la fournaise volcano and inferred mass transfer during the 2007 crisis abstract the structure and mass transfers at piton de la fournaise volcano are investigated using new on land and offshore measurements the structures are defined using 2 and 3d modelling short wavelength positive anomalies to the w and nw of the central area are interpreted as shallow piles of thick dense lava flows which have filled volcano tectonic depressions several hundreds of meters deep this finding provides a new insight into the evolution of the volcano conversely the currently active central zone is associated with a negative short wavelength anomaly explained by the presence of thin highly vesiculated and fractured lava flows building the central cone low density formations underlying the rivieres des remparts and langevin areas are tentatively interpreted as breccias related to erosion and or to southward directed mass wasting topographic offshore highs in the continuation of the se and ne rift zones of piton de la fournaise are characterized by negative gravity anomalies and reversed magnetic anomalies their interpretation as hyaloclastites and pillow lavas provides a coherent explanation for both types of signals if we admit that they were primarily constructed during the alizes stage two main deeper dense structures are also found the grand brule complex and a complex beneath the plaine des sables and the enclos fouque both are identified as hypovolcanic intrusive complexes the grand brule complex 10 18 km in plan view shows a marked ns elongated geometry unlike the other comparable complexes on the island the plaine des sables enclos fouque complex a more or less circular structure 5 km in diameter is attributed to the ancient shield stage it is centered on the enclos fault suggesting that the paleo center of the ancient shield was located about 1 5 km eastward of the previously proposed location an apparent contradiction was noted between the seismic and gravity images of the internal structure in particular a high velocity cylinder beneath the summit was not detected in the gravity models this contradiction was resolved by considering the relative sensitivity of each method finally the gravity dataset has allowed us to explore the gravity changes that accompanied the major eruptive and volcano tectonic crisis of april 2007 350 m collapse of the summit and emission of 120 106 m3 of lava the change in the mass distribution of the edifice was large enough to be detected in the survey data collected in the central area before and after the crisis however the accuracy was too low for the precise assessment of the mass transfers

the retention of primary oxygen isotope compositions of fossil elephant skeletal phosphate fossil elephant remains from sediments of plio pleistocene age in the vicinity of lake turkana kenya provide insights into the ability of the phosphate oxygen system to preserve original 18o values 18op in the depositional environment individual fossil specimens exhibit systematic variations in the 18op values of their various tooth and bone components differences in 18op values between these skeletal components can be as high as 3 6 despite the fact that equivalent phases for individual modern elephants have 18op values which vary by less than 0 6 xrd traces of the different skeletal phases of modern and fossil samples also infer differential preservation of primary apatite crystallinities among the various fossil phases fossil samples of dentine cementum and bone have x ray spectra with sharper and more intense peaks compared to their modern counterparts but little change in crystallinity is observed for fossil enamel samples a model based on the premise that the enamel phase preserves primary isotope signatures and that the accompanying skeletal phases are partially re equilibrated with the fluids associated with the microbial decomposition of the elephant s carcass is consistent with the features of the 18op dataset this isotopic evidence in conjunction with the physical and chemical attributes of enamel has led us to postulate that enamel could be preserving primary isotope signatures while other skeletal components are affected to varying degrees by alteration processes in the burial environment

the april 2007 eruption and the dolomieu crater collapse two major events at piton de la fournaise la reunion island indian ocean abstract after 10 years of high activity and 24 eruptions piton de la fournaise pdf produced on april 2 to may 1 2007 one of its most voluminous and intense eruption since at least one century the eruption focused at 590 m elevation in the grand brule on the south east flank of piton de la fournaise 7 km away from summit it was located close to the southern cliff of the grand brule volcano tectonic collapse the rempart du tremblet and to the nearby village called le tremblet and it highly rattled and incommoded the inhabitants there eleven hours after the beginning of the eruption the lava flows reached the sea and created 0 45 km 2 of new land until the end of eruption in the night of april 5 the rock column beneath dolomieu crater started to collapse with a piston like mechanism into the magma chamber forming within less than 24 h the most recent and well documented caldera we report in this paper the chronology of these two related major events in the recent activity of pdf seen by the scientific networks of the volcanological observatory ovpf ipgp and field observations which allowed to back up the scenario of the caldera formation and to quantify these two exceptional episodes

final remark on modeling transient stream aquifer interaction with the non linear boussinesq equation and its analytical solution by serrano s e workman s r 1998 journal of hydrology 206 245 255

internal structure of piton de la fournaise volcano from seismic wave propagation and earthquake distribution abstract arrival times of seismic waves from local earthquakes are inverted for both locating the source and defining the 3 d velocity heterogeneity of piton de la fournaise the lateral heterogeneity of the 2632 m high edifice is resolved as a high velocity plug 1 5 km in diameter surrounded by a low velocity ring which may be interpreted as due to the construction of fournaise on the flank of the older volcano piton des neiges wave mode conversion detected on three component seismograms provides evidence for boundaries of contrasted velocities pre eruptive swarm earthquakes cluster in the high velocity zone under the dolomieu summit crater low strength and cohesion of the surrounding material account for the lack of seismicity for the final 1 3 km radial flow of magma to the vents in enclos fouque beneath the high velocity plug the existence of a body with low velocity for p and even for s waves is well constrained however the walls and base are poorly defined because of the lack of deep earthquakes for sampling the few earthquakes that are located in this depth region usually occur at a depth of around 1 5 km below sea level in the region of the cone this can be considered providing the upper constraint on the lower limit of the aseismic part of the low velocity body the coincidence in time of their occurrence with the swarms above sea level and the eruptions suggests magmatic activation of the low velocity aseismic volume 1 5 km below sea level under the high velocity plug of the cone further down the concentration of seismicity in two swarms between 2 and 4 km under the eastern flank does not allow the structure to be sampled effectively

reply to comment on analytical solutions of the nonlinear groundwater flow equation in unconfined aquifers and the effect of heterogeneity by sergio e serrano

magma transport and storage at piton de la fournaise la reunion between 1972 and 2007 a review of geophysical and geochemical data abstract since the middle of the 20th century improvement in volcano monitoring techniques has provided large data sets that can be used to evaluate the evolution of magma plumbing systems at piton de la fournaise volcano abundant eruptive activity and a dense monitoring network are especially conducive to such research analysis of the extensive set of geophysical and geochemical data associated with the last 35 years of activity provides new insights into magma transport and storage at piton de la fournaise two periods of frequent eruptions separated by 6 years of inactivity can be distinguished 1972 1992 and 1998 2007 considering these two periods we show evidence of major changes in the shallow plumbing system in 2000 during 1972 1992 and 1998 2000 lava compositions and weak long term eruptive precursors lasting few days to three weeks characterized by no significant summit inflation and about ten volcano tectonic earthquakes per day suggest that eruptions were fed by the progressive drainage of an occasionally recharged shallow magma reservoir geophysical evidence of shallow magma reservoir recharge was only recorded in 1986 and 1998 in contrast from 2000 to 2007 geophysical data highlight the appearance of long term precursors 1 to 5 months of summit inflation and strong seismicity up to one hundred events per day preceding cycles of successive eruptions each cycle of eruptions was characterized by a sequence 3 to 10 months in duration of summit and near summit proximal eruptions and ended with a distal low altitude oceanite olivine abundances 20 vol eruption on the eastern flank of the volcano within each of these eruptive cycles lavas became progressively more magnesian over time the preferential motion of the eastern flank caused by continuous recharging of the shallow reservoir since 2000 would favour the occurrence of distal eruptions towards this flank at the end of a cycle

anatomy of piton de la fournaise volcano la reunion indian ocean the aim of this work is to propose a general model of piton de la fournaise volcano using information from geological and geophysical studies firstly we make a graphical compilation of all available geophysical information along a w e profile secondly we construct a geological section that integrates both the geophysical information and the geological information the lithosphere beneath piton de la fournaise is not significantly flexed and the crust is underlain by an underplating body which might represent the deep magma reservoir for la reunion volcanism piton de la fournaise is a relatively thin volcano lying on a huge volcanic construction attributed mostly to les alizes volcano indeed if the differentiated rocks observed at the bottom of the riviere des remparts are the top of les alizes volcano the interface with piton de la fournaise may be located at about sea level beneath the summit area the endogenous constructions intrusive complexes related to les alizes and piton de la fournaise volcanoes represent a large volume the huge intrusive complex of les alizes volcano probably rests on the top of the oceanic crust and appears to have a buttressing effect for the present eastern volcano tectonic activity of piton de la fournaise the early piton de la fournaise edifice was built around a focus located beneath the plaine des sables area the center subsequently moved 5 6 km eastward to its current location the dense high velocity body beneath the plaines des sables and the western part of the enclos probably corresponds to the hypovolcanic intrusive complex that developed before the volcanic center shifted to its present day position magma reservoirs may have existed and may still exist as illustrated by the march 1998 crisis at the mechanical and density interface between the oceanic crust and the les alizes edifice strong evidence also exists for the presence of a shallower magma reservoir located near sea level beneath the summit the march 1998 pre eruptive seismic pattern location and upward migration seems to be evidence for a transfer of magma between the two reservoirs the dominant structural feature of the central zone is a collapse structure beneath the summit craters above the inferred magma reservoir near sea level the collapsed column constitutes a major mechanical heterogeneity and concentrates most of the seismic intrusive and hydrothermal activity because of its higher permeability and weaker mechanical strength

three dimensional streamlines in dupuit forchheimer models an approximate method is presented for determining streamlines in three dimensions using two dimensional dupuit forchheimer models the latter models of horizontal flow which may comprise several aquifers are based on the assumption that the resistance to flow in the vertical direction is neglected this assumption does not preclude the occurrence of flow in the vertical direction vertical components of flow are determined in an approximate fashion by requiring continuity of flow the problem of leakage from a shallow pond above an unconfined aquifer is discussed as an example of determining streamlines in three dimensions the errors induced by the approximation are determined for a few idealized flow problems that can be solved exactly

dendritic crystallization a single process for all the textures of olivine in basalts the olivine macrocrysts found in oceanites picrites and magnesian basalts erupted at hotspot volcanoes are generally interpreted either as phenocrysts crystallized from the magma or as xenocrysts extracted from a deforming cumulate to constrain the origin of these crystals we studied their texture and composition at piton de la fournaise volcano la reunion we show that macrocrysts are organized and subdivided into parallel units this suggests a crystallization by dendritic growth and ripening rather than by a complex combination of paired nucleation crystal aggregation or synneusis dendritic growth is also evidenced by the occurrence of hollow faces p rich zones melt and cr spinel inclusions formed from the accumulation of slow diffusing impurities p cr al in the liquid at the contact with rapid growing olivine we suggest that early dendritic crystallization may even cause branch misorientations and lattice mismatches yielding subgrain boundaries dislocation lamellae and to a certain extent undulose extinction which have all been formerly interpreted in terms of plastic intracrystalline deformation we interpret olivine macrocrysts as phenocrysts crystallized under a strong degree of undercooling t 60 c and derived from a harrisitic mush formed on the cold walls of the magma reservoir given the growth shapes indicated by p zoning patterns and external faces the olivine macrocrysts which consist of groups of several subcrystals have grown in suspension within the liquid and were neither aggregated into a dense cumulate nor corroded shocked or deformed before or during their transport to the surface the major consequence of our study is that most olivine macrocrysts are not xenocrysts and very few of them if any have experienced intracrystalline deformation the importance of deforming creeping cumulate bodies thought to accommodate the spreading of basaltic volcanoes in la reunion and hawaii may hence have been overestimated

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

imaging the dynamics of dyke propagation prior to the 2000 2003 flank eruptions at piton de la fournaise reunion island 1 the relationship between shallow magma storage and flank injections in volcanic edifices is rarely documented we analyse the time series of geodetic and seismic data collected at piton de la fournaise volcano la reunion during 9 flank eruptions from 2000 to 2003 the data depicts how magma injections supplied flank eruptions at piton de la fournaise volcano and allows to precisely determine the direction and duration of dike intrusions indicating a two phases pattern consistent over all the eruptions 1 fast vertical migration of the dyke 2 m s from the magma chamber to the surface in 10 to 50 minutes and 2 slower lateral migration 0 2 0 8 m s in tens of minutes to hours controlled by the rift zone geometry

petrology of 1977 to 1998 eruptions of piton de la fournaise la reunion island abstract geochemical and petrological variations in 35 historical eruptions from the april 1977 eruption to the march september 1998 eruption at piton de la fournaise have been analyzed for their major elements abundances mineralogical compositions and oxygen isotopes during these 21 years samplings were repeated several times during eruptions as well as temperature measurements since the end of 1977 to 1998 all erupted lavas except 1998 hudson basalt belong to the group of the steady state basalts however evidences for small degrees of differentiation can be observed during a single eruption the earliest lava emitted contains less phenocrysts and has almost always a lower mgo mgo mgo feot than the lavas emitted later suggesting that it is more differentiated from one eruption to the next between 1977 and 1998 bulk compositions are more and more differentiated towards the first lava of 1998 a process of low pressure fractional crystallisation involving small proportions of olivine clinopyroxene and plagioclase allows to explain this evolution a major result of our study is to show that this evolution does not correspond to a unique fractionation trend over the considered period different types of magmas have been distinguished the first magma type erupted from october 1977 to november 1987 was richer in potassium 0 82 wt in average than the second one and apparently derived from the liquid of the 1977 oceanite the second magma type erupted from february 1988 to september 1998 was poorer in k 2 o 0 69 wt in average in march 1998 a third magma type hudson basalt erupted simultaneously with the second one hudson basalt has undergone a wehrlitic fractionation and is supposed to come from a deeper magma reservoir than other erupted magmas for this period from 1977 to 1998 the 18 o of lavas progressively decreases with time together with the increasing chemical differentiation of the magmas by low pressure fractional crystallisation this variation agrees with the hypothesis of magma contamination at shallow level in the altered volcanic edifice vlastelic i deniel c bosq c telouk p boivin p bachelery p famin v staudacher t 2009 this issue pb isotope geochemistry of piton de la fournaise historical lavas journal of volcanology and geothermal research 184 63 78 this issue overall petrological variations are in good agreement with a model of a shallow reservoir discontinuously supplied between 1977 and 1998 the speed of the variations the coexistence of different liquids the chemical evolution of the lavas during the same eruption lead us to favour a model of chemically stratified reservoir constituted by a complex of dykes sills and laccoliths close to the surface and located above larger magma bodies

steady annual and monthly recharge implied by deep unconfined aquifer flow abstract we consider the response of a deep unconfined horizontal aquifer to steady annual and monthly recharge a groundwater divide and a zero head reservoir constrain the aquifer so that sinusoidal monthly and aperiodic annual recharge fluctuations create transient specific discharge near the reservoir and an unsteady water table elevation inland one existing and two new long term data sets from the plymouth carver aquifer in southeastern massachusetts calibrate and confirm hydraulic properties in a set of analytical models geohydrology and simulated groundwater flow 1992 data and a new power law for tritiugenic helium to tritium ratios calibrate the steady recharge that drives the classical parabolic model of steady hydraulics applied hydrogeology 2001 observed water table and gradient fluctuations calibrate the transient recharge models in the latter regard monitoring wells within 1 km of buttermilk bay exhibit appreciable specific discharge and reduced water table fluctuations we apply trans am geophys union 32 1951 238 periodic model to the monthly hydraulics and a recharge convolution integral j hydrol 126 1991 315 to annual flow an infiltration fraction of 0 79 and a consumptive use coefficient of 1 08 10 8 m s c relate recharge to precipitation and daylight weighted temperature across all three time scales errors associated with this recharge relation decrease with increasing time scale

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

water table fluctuation owing to time varying recharge pumping and leakage this paper presents an analytical solution of a 2 d linearized boussinesq equation to predict water table variation in a horizontal aquifer induced by time varying recharge and or withdrawal from any number of recharge basins pumping wells and leakage sites of different dimensions the rate of time varying recharge or withdrawal is approximated by series of line elements of different lengths and slopes depending on the nature of variation of recharge or withdrawal rate advantage of this approximation scheme is that any complex nature of recharge and or withdrawal rates for any number of recharge basins pumping wells and leakage sites and for any number of these operations can be approximated with more accuracy application of the solution in the prediction of water table variation in the presence of time varying recharging pumping and leakage is demonstrated with the help of an example problem the present analytical solution is validated by comparing its results with the corresponding numerical results obtained from modflow for the same example problem

cannibalism of olivine rich cumulate xenoliths during the 1998 eruption of piton de la fournaise la reunion hotspot implications for the generation of magma diversity contrasting with its unusual isotopic homogeneity compared to other hotspot volcanoes piton de la fournaise has produced a large diversity of basaltic magmas over its 0 5 ma history picrites and two types of transitional basalts with distinct petrological and chemical compositions a minor group of evolved basalts anomalous group of basalts or agb is enriched in both compatible mg fe ti cr and ni and incompatible k th and la elements and depleted in ca and si relative to the dominant group of evolved basalts the 1998 eruption simultaneously produced the two basaltic types at two distinct vents hudson vent agb kapor vent common basalt but from the same feeding conduit glasses of both magmas are close in composition and belong to the single differentiation trend defined by all 1998 2007 glass compositions thermodynamic model melts code shows that agb type magmas cannot be produced by high pressure 1 gpa clinopyroxene fractionation as previously proposed and that all melts of the 1998 2007 activity period are produced by low pressure 800 mpa crystal fractionation from the most primitive basalt mgo 9 modal composition of 1998 lavas mass balance calculation and sem image analysis and olivine crystal composition show that hudson lavas have assimilated significant fractions of olivine xenocrysts contrary to kapor lavas in addition the higher incompatible element contents of hudson lavas suggest contamination by a differentiated trachytic melt all agb share the following characteristics i evolved glass compositions ii 5 10 olivine xenocrysts and iii vents located in a narrow region at the summit of the edifice they are interpreted as the result of the assimilation of olivine rich xenoliths either by evolved melts or by basaltic melts contaminated by low fractions of differentiated melts produced from interstitial glass frequently coating cumulates minerals or resulting from partial melting of cumulates bearing pyroxene or plagioclase wehrlitic to gabbroic cumulates the scarcity of agb magmas is attributed to their shallow transfer path in rarely intruded lateral zones of piton de la fournaise volcano wehrlitic to gabbroic cumulates bodies are either heterogeneously distributed within the edifice or have been depleted in low melting point components in the rift zone where most of the recent eruptive events are emplaced these results emphasize the exceptional chemical homogeneity of the primary basaltic melt involved in volcanic activity of piton de la fournaise hotspot for 0 5 ma and the increasingly recognized role of magma wall rock interactions in erupted magma compositions

groundwater flow in sloping aquifer under localized transient recharge analytical study abstractthis paper analyzes the groundwater flow system in an unconfined downward sloping aquifer of semi infinite extent in response to localized transient recharge the aquifer is in contact with a water body of constant water level at one end and receives localized transient recharge from a recharge basin of finite width the mathematical model is based on the boussinesq equation with dupuit forchheimer assumption in which the spatial coordinate of the recharge basin is treated as an additional parameter analytical solutions of the linearized boussinesq equation are obtained using the laplace transform technique by dividing the aquifer in a three zone system containing both dirichlet and neumann boundary conditions at the hypothetical interfaces upward and zero sloping cases are deduced from the main results by appropriately adjusting the slope parameter to assess the validity and efficiency of the linearization method the nonlinear boussinesq equation is also solved using a fully explicit predic

groundwater dynamics due to general stream fluctuations in an unconfined single or dual porosity aquifer subjected to general areal recharge abstract analytical solutions of groundwater dynamics in an elongated aquifer subjected to general time dependent recharge are presented the lateral boundaries are specified heads with the head variations governed by general time dependent functions general recharge function was not considered in previous works of this kind both single and double porosity aquifers are considered the solution is obtained using fourier sine and laplace transformations followed by an inverse fourier laplace transform involving residue theorem and convolutional integral for the unconfined single porosity aquifer case the exact time domain solution is obtained using the residue theorem for the unconfined double porosity aquifer case the time domain head is calculated using the de hoog inverse laplace algorithm the presented solution can be used to estimate the hydraulic parameters of 1 groundwater head variation of a river basin aquifer subjected to general lateral head variation and recharge 2 groundwater head variation in a double porosity elongated fractured anticline 3 groundwater depletion of an elongated fractured anticline subjected to recharge due to rainfall or snowmelt to its adjacent alluvial aquifer in addition the presented solution can be utilized to optimize the irrigation pattern in a cropland between two trench drains to control the groundwater mound

fully conservative coupling of hec ras with modflow to simulate stream aquifer interactions in a drainage basin this work describes the application of a methodology designed to improve the representation of water surface profiles along open drain channels within the framework of regional groundwater modelling the proposed methodology employs an iterative procedure that combines two public domain computational codes modflow and hec ras in spite of its known versatility modflow contains several limitations to reproduce elevation profiles of the free surface along open drain channels the drain module available within modflow simulates groundwater flow to open drain channels as a linear function of the difference between the hydraulic head in the aquifer and the hydraulic head in the drain where it considers a static representation of water surface profiles along drains the proposed methodology developed herein uses hec ras a one dimensional 1d computer code for open surface water calculations to iteratively estimate hydraulic profiles along drain channels in order to improve the aquifer drain interaction process the approach is first validated with a simple closed analytical solution where it is shown that a piccard iteration is enough to produce a numerically convergent and mass preserving solution the methodology is then applied to the groundwater surface water system of the choele choel island in the patagonian region of argentina smooth and realistic hydraulic profiles along drains are obtained while backwater effects are clearly represented

development and verification of a 3 d integrated surface water groundwater model summary coupled modelling of surface and subsurface systems is a valuable tool for quantifying surface water groundwater interactions in the present paper the 3 d non steady state navier stokes equations after reynolds averaging and with the assumption of a hydrostatic pressure distribution are for the first time coupled to the 3 d saturated groundwater flow equations in an integrated surface water groundwater model irene a finite difference method is used for the solution of the governing equations of irene a semi implicit scheme is used for the discretisation of the surface water flow equations and a fully implicit scheme for the discretisation of the groundwater flow equations the two sets of equations are coupled at the common interface of the surface water and groundwater bodies where water exchange takes place using darcy s law a new approach is proposed for the solution of the coupled surface water and groundwater equations in a simultaneous manner in such a fashion that gives computational efficiency at low computational cost irene is verified against three analytical solutions of surface water groundwater interaction which are chosen so that different components of the model can be tested the model closely reproduces the results of the analytical solutions and can therefore be used for analysing and predicting surface water groundwater interactions in real world cases

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

aquifer response to stream stage and recharge variations ii convolution method and applications abstract in this second of two papers analytical step response functions developed in the companion paper for several cases of transient hydraulic interaction between a fully penetrating stream and a confined leaky or water table aquifer are used in the convolution integral to calculate aquifer heads streambank seepage rates and bank storage that occur in response to stream stage fluctuations and basinwide recharge or evapotranspiration two computer programs developed on the basis of these step response functions and the convolution integral are applied to the analysis of hydraulic interaction of two alluvial stream aquifer systems in the northeastern and central united states these applications demonstrate the utility of the analytical functions and computer programs for estimating aquifer and streambank hydraulic properties recharge rates streambank seepage rates and bank storage analysis of the water table aquifer adjacent to the blackstone river in massachusetts suggests that the very shallow depth of water table and associated thin unsaturated zone at the site cause the aquifer to behave like a confined aquifer negligible specific yield this finding is consistent with previous studies that have shown that the effective specific yield of an unconfined aquifer approaches zero when the capillary fringe where sediment pores are saturated by tension extends to land surface under this condition the aquifer s response is determined by elastic storage only estimates of horizontal and vertical hydraulic conductivity specific yield specific storage and recharge for a water table aquifer adjacent to the cedar river in eastern iowa determined by the use of analytical methods are in close agreement with those estimated by use of a more complex multilayer numerical model of the aquifer streambank leakance of the semipervious streambank materials also was estimated for the site the streambank leakance parameter may be considered to be a general or lumped parameter that accounts not only for the resistance of flow at the river aquifer boundary but also for the effects of partial penetration of the river and other near stream flow phenomena not included in the theoretical development of the step response functions

transient solution for stream unconfined aquifer interaction due to time varying stream head and in the presence of leakage summary this paper presents new analytical solutions of a linearized boussinesq equation characterizing groundwater flow in a stream unconfined aquifer system due to transient seepage the aquifer is underlain by a horizontal leaky bed and interacts with an adjoining stream of varying water level through a semipervious vertical stream bank close form analytical expressions are derived to predict water head distribution flow rate and volumetric exchange of water in response to time dependent rise or drop in the stream water level comparison between analytical and numerical results shows satisfactory agreement the effects of the finite and semi infinite lengths of the domain are considered in detail certain asymptotic situations such as sudden rise or drop in the stream water level no flow condition at the aquifer s base and absence of vertical stream bank can be dealt with as limiting cases of main results an illustration of the new analytical approach is used to quantify the accretion recession of the bank storage due to variation in various aquifer parameters

cumulate clasts in the bellecombe ash member piton de la fournaise reunion island and their bearing on cumulative processes in the petrogenesis of the reunion lavas abstract among the ejecta from a phreatomagmatic eruption on piton de la fournaise volcano are wehrlitic and gabbroic cumulate clasts these fresh samples comprise olivine fo85 0 to fo69 0 augite en47 1wo44 6wo44 6 to en41 1fs15 4wo43 5 and plagioclase an82 8ab16 8or0 4 to an53 8ab44 8or1 4 with spinel ti rich ferrichromites to ti magnetite and some ilmenite a few percent of highly vesicular interstitial glass is commonly present textures indicate that the cumulates were not wholly crystalline at the time of eruption and that the glass represents a residual intercumulus melt that varies from basaltic to mugearitic sulphide globules typically spherical and up to 40 m diameter represent immiscible melts within the glasses the sulphides contain relatively high contents of cu and ni and appear to be high temperature homogeneous pyrrhotite rich compositions rank order of element abundance in the sulphides is fe s cu ni co and zn wt s although in one sample ni is more abundant than cu lack of correlation between the sulphide globule compositions and their host glasses is probably due to complex partitioning between the silicate melts silicate and oxide crystals sulphide melt and separating volatile phase whereas the cu cu ni at values of the sulphides are similar to those of the sulphide ore bodies from major gabbroic complexes the ni ni fe values are notably high with regard to the low mgo content of their host glasses oxide pairs regarded as reflecting equilibria prior to eruption indicate temperatures of 1017 897 c and log fo2 values of 9 6 12 7 compaction of analogous cumulate mushes with extraction of relatively low density basaltic to mugearitic and ultimately trachytic residual melts is inferred to have yielded the differentiated series lavas and ash flows of the older volcano on reunion piton des neiges the sequence of crystallisation with augite as the second silicate phase rather than plagioclase as is normal in the lava sequences suggests crystallisation at depths 5 km the bellecombe ash cumulate clasts show more evolved assemblages than most other xenolith suites on the volcano in which dunites predominate and are probably products of stagnated magma batches possibly arrested in sill like intrusions in the deeper crust the cumulates are recent components in what is probably a large ca 70 km across layered complex beneath the volcanic edifices accreted during the build up of reunion

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

evidence for a homogeneous primary magma at piton de la fournaise la reunion a geochemical study of matrix glass melt inclusions and pele s hairs of the 1998 2008 eruptive activity abstract magmas erupted at piton de la fournaise volcano since 0 5 ma display a large petrological and chemical range picrites 2 types of transitional basalts and differentiated magmas and low amplitude isotopic heterogeneities the recent activity 1998 2008 includes all magma types except evolved magmas matrix glass compositions from quenched lavas and pele s hairs of the whole 1998 2008 period define a single differentiation trend from a common basaltic melt mgo 9 for the first time identified in the 2007 magmas more primitive melt compositions mgo 12 5 are only evidenced by olivine crystals with high fo contents fo85 88 4 evolutions of major and trace element of glass and mineral compositions are consistently modelled by a unique low pressure crystal fractionation process the composition range of olivine melt inclusions is distinct from that of matrix glass and pele s hair and corresponds to equilibrium crystallisation in closed system of melts trapped from the main differentiation series at high temperature the range of basaltic types at piton de la fournaise is the result of large variations in the differentiation degree 10 to 35 crystallisation of a single primary basaltic melt and the addition in highly variable amounts up to 50 in picrites of co genetic olivine or gabbroic cumulates these cumulates may represent the shallow and dense bodies identified by seismic tomography and have likely been produced by the repetitive intrusion and differentiation of basalts along piton de la fournaise history depending on the shallow transfer paths ascending magmas may disaggregate and incorporate various types of cumulates explaining all particular features of basaltic magmas and picrites these results emphasize the exceptional chemical homogeneity of the primary basaltic melt and of the differentiation process involved in volcanic activity of la reunion hotspot since 0 5 ma and the increasingly recognised role of melt wall rock interactions in compositional and petrological diversity of erupted magmas

applicability of analytical solutions to tidal propagation in circular islands abstract the propagation of tides into coastal aquifers is an important phenomenon in the migration of coastal contaminants for the representation of shoreline boundary conditions in regional scale groundwater models and for the estimation of aquifer properties based on tidal amplitude attenuation and or phase increase in this study an analytical solution to the propagation of tidal fluctuations in a radial flow field applicable to circular islands is compared to the existing straight coastline ferris solution the analytical solution is compared to numerical simulation using seawat of a simple harmonic ocean tide and its propagation within a circular island this represents the first attempt to combine a previous correction that allows seawat to simulate axisymmetric flow and a modification to seawat to create tidal boundary conditions bench testing the analytical solution against the numerical model confirms the numerical approach the circular island solution is compared to the ferris solution in terms of tidal amplitude decay and phase shift whereas amplitude decay from the ferris solution is valid only for near shore locations within circular islands the ferris solution produces reasonable phase lag estimates for typical aquifer diffusivities and for most locations within circular islands by comparing the ferris and circular island solutions we propose a correction factor to the ferris solution that allows it to be applied in circular boundary settings this extends the application of the widely applied ferris solution to a broader range of situations

a semianalytical solution for the boussinesq equation with nonhomogeneous constant boundary conditions the boussinesq groundwater equation is widely used in hydrology to predict streamflow from an unconfined aquifer and derive the aquifer s saturated hydraulic conductivity and drainable porosity and to predict water table height in drainage engineering in this work we solve this equation in an unconfined horizontal aquifer for nonhomogeneous boundary conditions for the water table height the solution is found in the form of a taylor series that has a finite radius of convergence which is different for each initial condition we also present an expression for the flux boundary condition at the origin as a function of the depth of the adjoining stream that automatically satisfies the boundary condition at infinity and thus eliminates the need for a trial and error approach for the solution which is accurate to 10 7 in order to obtain an approximation for the water table height in the region where the series solution diverges first we computed a diagonal pade approximation from the series coefficients which converges in a larger interval than the series and then we matched it with a new asymptotic approximation for large values of the independent variable we found that the proposed matched solution is better suited to cases where the water head at the origin is close to the initial water head in the aquifer

perturbation to the lithosphere along the hotspot track of la reunion from an offshore onshore seismic transect a 250 km long ne sw lithospheric transect spanning the 40 km wide island of la reunion and its submarine edifice is derived from lines of air gun shots at sea on either side along the assumed hotspot trace seismic records were obtained from an array spanning the whole transect and including sea bottom and land receivers providing a system of reversed and overlapping observations low seismic velocity and hence density is found on average for the whole edifice above the oceanic plate we attribute high velocity anomalies within the edifice to an intrusive core confined under the central northern quarter of the island crossing segment unexpectedly the main seismic interfaces top and bottom of the prevolcanic crust do not show significant flexural downwarping under the island in addition clear multipathing in the recorded wave field requires the presence of a body with a seismic velocity intermediate between the prevolcanic crustal material and the normal mantle this lithospheric structure provides the first example where underplating occur s beneath an active volcanic island suggesting a genetic relationship the underplated body could represent residues of the evolution of primary picritic melts that yield erupted basalts evidence for reflectors deeper in the lithosphere may indicate further related heterogeneity in the plate hotspot model commonly assumed the structural variation along the transect could be interpreted as a variation with time of the amount and physical state of underplated material

constraints on magma transfers and structures involved in the 2003 activity at piton de la fournaise from displacement data piton de la fournaise reunion island had shown 8 months of high activity during 2003 including four eruptions and one intrusion the monitoring networks provided by the volcanological observatory of piton de la fournaise show two different kinds of behavior strong and rapid deformations linked with the magma injections and a slight continuous intereruptive inflation of the summit area inversed modeling based on the deformation data using a three dimensional elastostatic boundary element code combined with seismicity provides new insights into the volcanic feeding system involved in the 2003 activity 1 the 2003 eruptions are fed from a pressurized magma chamber located beneath the summit at 300 m above sea level 2 a vertical path was activated between the magma chamber and the surface during the december 2002 collapse allowing the magma to rise into it and leading to the initial summit eruption in may 2003 3 the august and september 2003 lateral eruptions had been fed by dikes intruding along the same vertical pathway at an estimated velocity of 1 1 to 1 3 m s before intruding the flank into the rift zones at a velocity of 0 2 to 0 8 m s this last point suggests a strong structural control on the dike pathway