atoll reef island formation and response to sea level change west island cocos keeling islands abstract reef islands around the margin of coral atolls generally comprise unconsolidated holocene sands and gravels overlying a reef flat or cemented conglomerate platform such islands have accreted within the last 3000 4000 years since sea level has reached a level close to present and the reef flat and conglomerate platform have formed island morphology consists of an oceanward ridge a less distinct lagoonward ridge and low lying central depression several alternative models of how such reef islands might have developed are examined in relation to chronology and sediment provenance particularly in the context of the cocos keeling islands where this issue has been debated since darwin visited the atoll which of these models appears most appropriate for an elongate reef island on the atoll margin is assessed using conventional radiocarbon dating of coral shingle and accelerator mass spectrometry ams radiocarbon dating of individual sand grains from pits across west island the dating results suggest that both coral clasts and individual grains of various components are generally reliable and replicable indicators of the chronology of island accumulation implying rapid transport of skeletal material after death of the contributing organisms across the reef flat zone and relatively little reworking the central part of west island appears to have formed first with oceanward accretion up until about 2000 years bp gradual oceanward accretion with lesser lagoonward extension has continued beyond 2000 years bp at the northern and southern ends of the island and a sequence of lagoonward recurving spits has formed adjacent to the inter island passage at the southern end of the island radiocarbon dating of fossil microatolls indicates a gradual fall of sea level over this period which appears to have had little effect on the pattern of island accretion

chemical stability of the atmosphere and ocean abstract the earth system processes most of the chemical components of its atmosphere and oceans in geologically short periods of time it does this in a regulated way one that maintains a remarkably constant surface environment this we know primarily from the fossil record of uninterrupted complex life on earth that extends over the last billion years we are only beginning to understand the feedbacks that control the chemistry of the oceans and atmosphere numerical models of biogeochemical cycles are most stable when there is feedback between the amount of a chemical component in the ocean or atmosphere and its transfer to or from that reservoir coupling of subsystem especially of those operating on different time scales enhances stability an example of the role of feedback in stabilizing earth s chemical environment is the mechanism of control of atmospheric oxygen there appears to be no strong relationship between oxygen level and oxygen consumption however oxygen production may be a function of oxygen level the burial rate of organic carbon oxygen production in marine sediments may be sensitive to bottom water oxygenation levels also combustion may be an effective mechanism of transferring nutrients namely phosphorus from efficient terrestrial ecosystems to less efficient marine ecosystems when o2 rises fires become more frequent and p is transferred to the ocean stimulating marine organic carbon burial but depressing global burial rates global o2 production rates decline as does the o2 level a negative feedback models of ocean chemical composition are presently incapable of reproducingthe temporal constancy indiated by geological observations these models do not incorporate ion exchange equilibria as important processes in marine geochemical cycles when included these equilibria significantly damp the fluctuations in ion ratios calculated by the extant models

the metal oxide fraction of pelagic sediment in the equatorial north pacific ocean a source of metals in ferromanganese nodules abstract pelagic sediment recovered at domes site a in the equatorial north pacific 151 w 9 15 n consists of a surface homogeneous layer approximately 10 cm thick overlying a strongly mottled layer that is lighter in color the radiolarian composition of both units is quaternary in areas where this sediment was only a few centimeters thick the underlying sediment was early tertiary clay mineralogy and major oxide composition of the two quaternary sediments are uniform their similarity to continental shale suggests that the sediment has a terrigenous source clay mineralogy and major oxide composition of the tertiary sediment also are uniform although they differ markedly from the quarternary sediment in contrast to the major oxides concentrations of mn co cu and ni soluble in hydroxylamine hydrochlorideacetic acid are strongly different in the surface and subsurface quaternary sediment mn and ni exhibit pronounced depletions in the subsurface sediment ni slightly more than mn cu is also depleted in the subsurface sediment but less than mn it is also depleted in the subsurface tertiary sediment whereas the mn concentration remains high concentration of co relative to mn increases into the subsurface quaternary sediment to a constant co mn ratio of 3 10 2 the trivalent ree the ree exclusive of ce and fe exhibit little down core variation distribution of elements in these sediments is closely related to their concentration in associated surface ferromanganese nodules the nodules are of two distinct types those from the area where the quaternary sediment is relatively thick have mno2 as the dominant manganese mineral the ratios of ni mn cu mn and fe mn in these nodules approximate the corresponding ratios of the soluble fraction of surface sediment todorokite is the dominant mineral of nodules recovered from areas where the quaternary sediment is thin relatively high cu mn ni mn and low fe mn ratios of these nodules mirror differences between the soluble fraction of surface and subsurface quaternary sediment these compositional trends of sediment and nodules at domes site a reflect a diagenetic origin for the todorokite nodules and a predominantly hydrogenous origin for the mno2 nodules

gravity changes before and after the 2008 m w 7 9 wenchuan earthquake at pixian absolute gravity station in more than a decade absolute gravity repeated measurements at pixian station about 35 km away from the epicenter of the 2008 wenchuan mw 7 9 earthquake have been carried out over more than a decade four pre earthquake measurements at the pixian station show 30 gals increase from 2002 to 2008 but 13 measurements since 2008 shows that the trend of gravity increase ended after the wenchuan earthquake we analyzed the gravity effects from ground vertical motions using data from continuous gps stations collocated with the pixian absolute gravimetry station and surficial and hydrological processes using local hydrological data we found that these effects are much smaller than the observed gravity increase before the earthquakes the continuously gravity increase before the 2008 wenchuan earthquake cannot be explained by the groundwater level change and vertical deformation and related superficial reasons all absolute gravity was measured by the fg 5 gravimeter in this study the high precision gravity change revealed that the pre earthquake gravity increase may be caused by strain and mass fluid transfer in broad seismogenic source regions further studies are needed to validate such pre earthquake gravity changes which however are difficult to be resolved from space based gravity models

phosphorus in foraminiferal sediments from north atlantic ridge cores and in pure limestones samples of foraminiferal ooze from two north atlantic cores were cleaned and progressively dissolved most of the p fe and mn was released during the first of two reductive cleaning steps most of the remainder of these elements and most of the ca were released during the final acid dissolution step the p in these samples is present largely in fe and mn rich coatings not as a constituent of the foraminiferal shells themselves our results are consistent with those of earlier studies the concentration of p in carbonate oozes in which it is clearly associated with coatings is similar to that of modern calcareous sediments in general and with that of reasonably pure limestones of all ages phosphorus is apparently associated with fe mn oxide coatings in many carbonate sediments the rate of removal of p from the oceans as a constituent of such sediments depends on the rate of formation of fe mn coatings not on the rate of incorporation of p into calcium carbonate

the urban geology of cairns queensland australia the urban geology of cairns on the northeast tropical coast of australia is dominated by quaternary sediments these sediments provide a record of sea level change alluvial and slope response to late quaternary climatic changes and millennial scale occurrences of various natural hazards drying of climate and consequent retraction of rainforest into refugia just prior to and after the last glacial maximum resulted in the construction of extensive high level alluvial fans and slope deposits which were incised following the amelioration of climate during the early holocene the holocene sea level record of the region is best shown by coral micro atolls which suggest that hydro isostatic rebound following flooding of the continental shelf resulted in a sea level fall of approximately 1 m since 5 5 ka coastal progradation following sea level stabilisation at approximately 6 ka has occurred with the deposition of sandy beach ridges and cheniers on a mud substrate these and other ridges on offshore islands along the great barrier reef were likely a result of deposition by storm surge and waves during tropical cyclones these millennial scale records highlight that extreme intensity tropical cyclones occur an order of magnitude more frequently than that suggested by the short not vert similar100 yr historical record of tropical cyclones from the region

submergence and uplift associated with the giant 1833 sumatran subduction earthquake evidence from coral microatolls the giant sumatran subduction earthquake of 1833 appears as a large emergence event in fossil coral microatolls on the reefs of sumatra s outer arc ridge stratigraphic analysis of these and living microatolls nearby allow us to estimate that 1833 emergence increased trenchward from about 1 to 2 m this pattern and magnitude of uplift are consistent with about 13 m of slip on the subduction interface and suggest a magnitude mw of 8 8 9 2 for the earthquake the fossil microatolls also record rapid submergence in the decades prior to the earthquake with rates increasing trenchward from 5 to 11 mm yr living microatolls show similar rates and a similar pattern the fossil microatolls also record at least two less extensive emergence events in the decades prior to 1833 these observations show that coral microatolls can be useful paleoseismic and paleogeodetic instruments in convergent tectonic environments

microatolls and recent sea level change on coral atolls microatolls are colonies of corals commonly porties which are dead on top but living around their perimeter and are found in intertidal environments on coral atolls they can grow to several metres in diameter their upward growth is constrained by sea level through prolonged exposure at the lowest spring tides1 2 and their dead upper surfaces have been limited by past sea levels they act as natural recorders of sea level which is of particular significance for coral atolls thought to be susceptible to inundation and erosion if sea level rises in response to global warming x radiographs of vertical slices through microatolls from the maldives and cocos keeling islands indian ocean and kiribati pacific ocean record sea level fluctuations over the past few decades there is a high degree of reproducibility between adjacent corals although on cocos we noted geographical variation in the pattern of change around the atoll the majority of microatolls sampled on these atolls record a slight fall in sea level over the past ten years

coral microatolls from the central pacific record late holocene el nino microatolls are discoid corals that have grown laterally because vertical growth is constrained by exposure at lowest tides we demonstrate that a modern reef flat porites microatoll from christmas kiritimati island preserves an oxygen isotope record of substantial sea surface temperature variations related to el nino southern oscillation enso we also show that a late holocene fossil microatoll from the centre of the island contains interannual oxygen isotope variations over an approximate 20 year period three pronounced negative isotope anomalies attributed to warm el nino events are superimposed on an annual cycle el nino events similar to those seen in recent decades appear to have been a feature of mid pacific climate in the late holocene analysis of further microatolls offers a source of pre instrumental el nino tropical climate data it may be possible to extend the nino c proxy to indicate intensity and frequency of enso over the past three millennia

an apparent contradiction in the role of phosphorus in cenozoic chemical mass balances for the world ocean little is known about the fluxes to and from the ocean during the cenozoic of phosphorus p a limiting nutrient for oceanic primary productivity and organic carbon burial on geologic timescales previous studies have concluded that dissolved river fluxes increased worldwide during the cenozoic and that organic carbon burial decreased relative to calcium carbonate burial and perhaps in absolute terms as well to examine the apparent contradiction between increased river fluxes of p assuming p fluxes behave like the others expected to drive increased organic carbon burial and observations indicating decreased organic carbon burial we determined p accumulation rates for equatorial pacific sediments from ocean drilling program leg 138 sites in the eastern equatorial pacific and leg 130 sites on the ontong java plateau in the western equatorial pacific although there are site specific and depth dependent effects on p accumulation rates there are important features common to the records at all sites p accumulation rates declined from 50 to 20 ma showed some variability from 20 to 10 ma and had a substantial peak from 9 to 3 ma centered at 5 6 ma these changes in p accumulation rates for the equatorial pacific are equivalent to substantial changes in the p mass balance however the pattern resembles neither that of weathering flux indicators 87sr 86sr and ge si ratios nor that of the carbon isotope record reflecting changes in organic carbon burial rates although these p accumulation rate patterns need confirmation from other regions with sediment burial significant in global mass balances e g the north pacific and southern ocean it appears that p weathering inputs to the ocean are decoupled from those of other elements and that further exploration is needed of the relationship between p burial and net organic carbon burial

the role of the subcutaneous zone in karst hydrology abstract the subcutaneous zone is the upper weathered layer of rock beneath the soil but above the permanently saturated phreatic zone it is of particular hydrological importance in karst because of its high secondary permeability arising from the considerable chemical solution in this zone however corrosional enlargement of fissures diminishes with depth thus permeability decreases in the same direction with the result that percolation is inhibited except down widened master joints and faults storage of water consequently occurs in this zone particularly after storms the upper surface of this suspended saturated layer in the subcutaneous zone is defined by a perched water table which slopes towards points of rapid vertical percolation the potential induces lateral water movement converging on the most permeable areas such as beneath dolines leakage from the subcutaneous store sustains slow percolation in the vadose zone cross correlation of rainfall with percolation rates in caves in new mexico u s a and new zealand reveal response lags of 2 14 weeks with no apparent relationship to depth below the surface other percolation sites show no correlation with rainfall interpreted as being a consequence of considerable friction in tight fissure networks the recognition of storage and rapid as well as very slow percolation from the subcutaneous zone requires re interpretation of the components of hydrographs from karst springs and of some conceptual models of karst aquifers the importance of subcutaneous storage in sustaining baseflow discharge at some sites must be recognised as must the contribution of subcutaneous water to flood hydrographs methods of estimating the volumes of subcutaneous and phreatic components of karst spring flood hydrographs are presented the paper concludes with a discussion of the significance of subcutaneous hydrologic processes for an understanding of karst geomorphology the desirability of explaining karst landform evolution in terms of hydrologic processes is stressed

dysaerobic conditions during heinrich events 4 and 5 evidence from phosphorus distribution in a north atlantic deep sea core abstract reactive phosphorus undergoes diagenetic transformation once transferred into marine sediments the degree of regeneration and redistribution of phosphorus depends on early diagenetic and environmental conditions which may be linked to larger scale phenomena such as bottom water circulation water column ventilation and organic carbon flux phosphorus phases of the

space geodetic observation of expansion of the san gabriel valley california aquifer system during heavy rainfall in winter 2004 2005 1 starting early in 2005 the positions of gps stations in the san gabriel valley region of southern california showed statistically significant departures from their previous behavior station long moved up by about 47 mm and nearby stations moved away from long by about 10 mm these changes began during an extremely rainy season in southern california and coincided with a 16 m increase in water level at a nearby well in baldwin park and a regional uplift detected by interferometric synthetic aperture radar no equivalent signals were seen in gps station position time series elsewhere in southern california our preferred explanation supported by the timing and by a hydrologic simulation is deformation due to recharging of aquifers after near record rainfall in 2004 2005 we cannot rule out an aseismic slip event but we consider such an event unlikely because it requires slip on multiple faults and predicts other signals that are not observed

evidence for smoothly falling sea level relative to north queensland australia during the past 6 000 yr post glacial sea level curves are expected to differ between different parts of the world as a result of global isostatic changes1 or perhaps other forms of geoidal changes2 i report here results from the inner part of the northern great barrier reef which seem to show a pattern of smoothly falling sea level during the past 6 000 yr the results are consistent with stratigraphical results from prograded mangrove coasts on the nearby north queensland mainland the region is remote from the tectonically active margin of the south west pacific ocean and the results contribute to the global data set relevant to isostatic changes being assembled by the international sea level project igcp project no 61 they also provide a baseline relevant to holocene coral reef growth in the inner great barrier reef

a compositional approach to the reconstruction of geochemical processes involved in the evolution of holocene marine flooded coastal karst basins mljet island croatia abstract geochemical patterns in the environment are always the result of certain processes therefore it is essential to decipher a process to properly evaluate the environmental role and potential of chemical elements compounds this allows the distinction between natural and anthropogenic influence on elemental concentrations however if the compositional nature of geochemical data is neglected erroneous or misleading conclusions regarding the processes involved are probable in this study the reconstruction of depositional environments and processes through the holocene in two sediment cores obtained from submerged sinkholes located on the island of mljet croatia was performed by taking into account the compositional nature of geochemical mineralogical and grainsize data problems involving compositional data are always multivariate for example the concentration of a single element does not carry any interpretative information as only the ratios between elements do this has led to the discovery of a large number of geochemical proxies based on elemental ratios which describe certain environmental conditions and processes involved nevertheless some proxies have been found to be restricted to only some specific environments thus preventing them from being used in general therefore some kind of relation between different proxies is necessary to obtain final conclusions however when using simple elemental ratios those correlations cannot be obtained due to the nature of compositional data with a sequential binary partition of a compositional vector orthonormal log ratio olr coordinates proxies can be constructed when based on expert knowledge those proxies fully acknowledge the geochemical properties of the chosen elements with one major difference that the correlation between newly obtained variables is mathematically well grounded as a result the final conclusion is more accurate in this research geochemical proxies obtained as a representation in olr coordinates of the elements that are enriched compared to the local soil were used to perform principal component analyses it helped to unravel the evolution of sedimentary environments mineralogical xrd and heavy mineral data and grain size analyses supported the conclusions obtained based solely on geochemical data furthermore data analysis suggests that the proxies for redox conditions described in the literature should be used with caution as their use is somewhat limited

gravity effect of water storage changes in a weathered hard rock aquifer in west africa results from joint absolute gravity hydrological monitoring and geophysical prospection advances in groundwater storage monitoring are crucial for water resource management and hydrological processes understanding the evaluation of water storage changes wsc often involve point measurements observation wells moisture probes etc which may be inappropriate in heterogeneous media over the past few years there has been an increasing interest in the use of gravimetry for hydrological studies in the framework of the ghyraf gravity and hydrology inafrica project 3 yr of repeated absolute gravity measurements using a fg5 type gravimeter have been undertaken at nalohou a sudanian site in northern benin hydrological data are collected within the long term observing system amma catch once corrected for solid earth tides ocean loading air pressure effects polar motion contribution and non local hydrology seasonal gravity variations reach up to 11 gal equivalent to a wsc of 260 mm thick infinite layer of water absolute temporal gravity data are compared to wsc deduced from neutron probe and water table variations through a direct modelling approach first we use neutronic measurements available for the whole vertical profile where wsc occur the vadose zone and a shallow unconfined aquifer the rmsd between observed and modelled gravity variations is 1 61 gal which falls within the error bars of the absolute gravity data second to acknowledge for the spatial variability of aquifer properties we use a 2 d model for specific yield sy derived from resistivity mapping and magnetic resonance soundings mrs the latter provides a water content mrs known to be higher than the specific yield hence we scaled the 2 d model of mrs with a single factor wsc are calculated from water table monitoring in the aquifer layer and neutronic measurements in the vadose layer the value of is obtained with amonte carlo sampling approach minimizing the rmsd between modelled and observed gravity variations this leads to sy mrs 0 63 0 15 close to what is found in the literature on the basis of pumping tests experiments with a rmsd value of 0 94 gal this hydrogeophysical experiment is a first step towards the use of time lapse gravity data as an integrative tool to monitor interannual wsc even in complicated subsurface distribution

fluxes to sediments underlying the rainbow hydrothermal plume at 36 14 n on the mid atlantic ridge abstract a geochemical investigation has been conducted of a suite of four sediment cores collected from directly beneath the hydrothermal plume at distances of 2 to 25 km from the rainbow hydrothermal field as well as a large biogenic component 80 caco3 these sediments record clear enrichments of the elements fe cu mn v p and as from hydrothermal plume fallout but only minor detrital background material systematic variations in the abundances of hydrothermal elements are observed at increasing distance from the vent site consistent with chemical evolution of the dispersing plume further pronounced ni and cr enrichments at specific levels within each of the two cores collected from closest to the vent site are indicative of discrete episodes of additional input of ultrabasic material at these two near field locations radiocarbon dating reveals mean holocene accumulation rates for all four cores of 2 7 to 3 7 cm kyr 1 with surface mixed layers 7 to 10 cm thick from which a history of deposition from the rainbow hydrothermal plume can be deduced deposition from the plume supplies elements to the underlying sediments that are either directly hydrothermally sourced e g fe mn cu or scavenged from seawater via the hydrothermal plume e g v p as holocene fluxes into to the cores surface mixed layers are presented which typically are an order of magnitude greater than background authigenic fluxes from the open north atlantic one core collected closest to the vent site indicates that both the concentration and flux of hydrothermally derived material increased significantly at some point between 8 and 12 14c kyr ago the preferred explanation is that this variation reflects the initiation intensification of hydrothermal venting at the rainbow hydrothermal field at this time perhaps linked to some specific tectonic event in this fault controlled hydrothermal setting

the marine phosphorus cycle phosphorus introduced to the ocean must ultimately be removed if a steady state is to be maintained over geologic time aeolian input is insignificant and there is evidently no hydrothermal contribution rivers dominate p input to the ocean the fluvial p flux is poorly quantified due to the interactions of two factors 1 man s influence on river nutrient fluxes and 2 inherent complexities in understanding the biological and inorganic associations of p in estuarine and coastal waters our best estimate of the natural or pre man p input flux is about 10 x 10 sup 9 moles p cm sup 2 ocean surface year of the identified flux of phosphorus to the sediments about 90 percent is in the form of biogenic debris or its regeneration products the burial of phosphatic fish debris is negligible p removal by direct reaction of phosphate in seawater with sea floor basalts during mid ocean ridge hydrothermal circulation is insignificant p removal by processes such as sorption on clay surfaces or formation of authigenic fe and al phosphate phases is presently unquantified and remains a serious uncertainty in the phosphorus cycle the identified sources and sinks approximately balance yielding a residence time for p in the oceans of about 10 sup 5 yrs

sedimentary phosphorus record from the oman margin new evidence of high productivity during glacial periods 1 the northern region of the arabian sea is one of the biologically most fertile regions of the world oceans with present productivity rates varying between 150 and 2500 mgc m2 day madhupratap et al 1996 this is related to the influence of the southwesterly summer monsoon which causes vigorous upwelling along the oman margin upwelling ceases during northeasterly winter monsoon activity productivity rates however remain relatively high about 800 mgc m2 day related to deep water mixing madhupratap et al 1996 the goal of this study is to verify if during the last glacial period a period in which winter monsoon conditions prevailed productivity rates were similarly high with an analysis of phosphorus phases stable nitrogen isotopes organic matter content and bulk mineralogy of the upper 10 m of the cores of odp hole 724c corresponding to the last 140 000 years sample resolution is 5 kyr we provide new evidence of high productivity during this last glacial period marine isotopic stages 2 3 and 4 this was probably related to the combined effect of 1 increased eolian input of iron containing dust due to dryness on the adjacent continent and stronger winter monsoon and 2 regeneration and diffusion of dissolved phosphorus from the sediments to the water column due to variations in the position and intensity of the oxygen minimum zone these findings suggest that there is no one to one relationship between summer monsoon activity and productivity which emerges to be a quasi persistent phenomenon across glacial and interglacial stages

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

monitoring deformation from hydrologic processes in a karst aquifer using long baseline tiltmeters 1 the aim of this study is to bring new information on water storage dynamics in karst systems from tiltmeter measurements newly developed long base hydrostatic tiltmeters are installed at two sites on the larzac plateau france in a karst aquifer of 100 km2 recharge area each site is located within a karst cave where two tilt directions are monitored significant reversible tilt deformation reaching amplitudes of 10 6 to 10 5 rad was observed at both sites following heavy precipitation elastic parameters were determined with an experiment in which a tiltmeter site was loaded by up to 25 t of weight at strategic locations at the ground surface mechanisms responsible for the observed tilt were then examined by means of finite element modeling deformation induced by water pressure changes in fractures is our preferred interpretation as the most plausible mechanism within this scope we used the tiltmeter responses to extract time constants using lumped parameter modeling time constants are interpreted to be associated with the filling and emptying of fractures nearby the tiltmeters these instruments therefore appear as useful tools to study the local dynamics of water infiltration in karst systems

structure and water storage capacity of a small karst aquifer based on stream discharge in southwest china summary karst spring stream discharge reflects the global configuration of the aquifer however quantitative description of the aquifer structure such as effective porosity neff and water storage capacity by the discharge analysis is difficult because of the complex conduit fracture system this study attempted to quantify the characteristics of karst aquifer based on discharge recession and time series analysis methods three recession models including modified maillet mangin and boussinesq models were evaluated to choose the most suitable one for analyzing the aquifer structure and auto correlation and cross correlation functions were applied to study the aquifer response in both year and rainfall event time scales the results showed that the modified maillet model was more suitable in the study catchment with mangin model overestimating and boussinesq model underestimating the discharge the neff was 3 73 for the total aquifer and it was 0 07 0 33 and 3 33 for the conduit fracture and matrix respectively based on a case study of a rainfall event with precipitation of 68 mm the water volumes drained by the three media were 25 43 33 40 and 41 17 respectively this indicates that although conduit network is not very developed with lower neff it is still an important water transmissive element draining more than a quarter of water after the rainfall event the memory time of the aquifer was 4 days for the year scale and 8 h for the rainfall event 68 mm scale this demonstrates that the aquifer has a well developed drainage system with a quick response to the rainfall the above results provide further insights for hydrological processes modeling and water resources management for the small catchment in karst regions

on the origin of late holocene sea level highstands within equatorial ocean basins abstract late holocene sea level highstands of amplitude 3 m are endemic to equatorial ocean basins these highstands imply an ongoing and moderate sub mm yr sea level fall in the far field of the late pleistocene ice cover that has long been linked to the process of glacial isostatic adjustment gia clark et al 1978 mitrovica and peltier 1991 coined the term equatorial ocean syphoning to describe the gia induced sea level fall and they provided the first physical explanation for the process they argued that water migrated away from far field equatorial ocean basins in order to fill space vacated by collapsing forebulges at the periphery of previously glaciated regions we provide a complete physical explanation for the origin of equatorial ocean syphoning and the associated development of sea level highstands using numerical solutions of the equation that governs meltwater redistribution on spherical viscoelastic earth models in particular we separate the total predicted sea level change into contributions associated with ice and meltwater loading effects and by doing so isolate a second mechanism that contributes significantly to the ocean syphoning process ocean loading at continental margins induces a levering of continents and a subsidence of offshore regions that has also long been recognized within the gia literature walcott 1972 we show that the influx of water into the volume created by this subsidence produces a sea level fall at locations distant from these margins indeed over the major ocean basins that is comparable in amplitude to the syphoning mechanism isolated by mitrovica and peltier 1991

global atmospheric loading and gravity abstract the purpose of this paper is to model atmospheric pressure effects on surface gravity pressure corrections are usually done with the help of an empirical trans fer function called barometric admittance between pressure and gravity both measured locally we show the validity of this local approach with the help of spectral coherency between air pressure and gravity residuals after subtraction from the superconducting gravimeter observations in strasbourg france of luni solar tides polar motion and instrumental drift contributions we compute the atmospheric surface loading effects using a green s function formalism and global surface pressure data provided by the european centre for medium range weather forecasts ecmwf we model a specific oceanic response to atmospheric loading which incorporates interactions between ocean atmosphere and solid earth and differs from the classical inverted or non inverted barometer hypotheses we investigate the contribution of this global pressure correction in a 3000 day 1987 1996 tidal analysis of the french superconducting gravimeter

absolute gravity monitoring of water storage variation in a karst aquifer on the larzac plateau southern france in this study we attempt to understand the water storage variations in a karst aquifer on the larzac plateau south of france using absolute gravimetry on this karst system water input is exclusively rainfall and draining occurs at the durzon perennial spring in a karstic valley our basis assumption is that water storage in the vadose zone epikarst and infiltration zone has a significant effect on surface gravity through newtonian attraction the karst aquifer is hence being monitored since january 2006 with monthly absolute gravity measurements at three sites the gravity measurements are corrected for regional scale gravity using water storage models in order to obtain gravity variations related exclusively to the local water storage variations the gravity variations exhibit an important seasonal component 10 15 mu gal corresponding to a variation of equivalent water stab thickness of similar to 24 36 cm water storage variation seen by gravimetry is not spatially uniform on the studied karst system corroborating current geomorphologic observations and interpretations finally we use a global mass balance consideration linking rainfall evapotranspiration and spring discharge to provide a conceptual framework for the understanding of observed gravity variations

distribution of various extracted phosphorus compounds in the interbedded turbiditic pelagic sediments of the madeira abyssal plain eastern north atlantic abstract a sequential extraction scheme was used to differentiate different p fractions in the interbedded turbiditic pelagic sediments of the madeira abyssal plain these fractions were carbonate associated exchangeable phosphate pex iron and aluminium associated phosphate poh calcium associated phosphate apatite phcl organic phosphorus porg and remaining phosphorus pr the pex forms a minor fraction of the total sedimentary phosphorus ptot whereas for most samples phcl represents near 80 of the ptot the amount of p in most fractions appears to be determined by the composition and provenance of the various turbidites the relatively high pex and the moderately high apatite p phcl for the sediment of turbidite e organicrich turbidite provenance group may point to a source area that is possibly upwelling related on the other hand the high phcl for the sediments of the turbidites b g n o p corresponds nicely to their volcanic and near coastal provenance area in contrast to this major impact of inherited p only a small contribution comes from p that is associated to post depositional re allocation of fe poh this results in a poh concentration that is slightly higher in the upper post depositionally oxidized layer of a turbidite than it is in the lower still un oxidized layer of the same turbidite in addition this postdepositional oxidation of the upper layer of a turbidite may also result in enhanced fe and p levels in the overlying pelagic interval the c p molar ratio for organic matter in these sediments is much higher than that reported for more recent sediments and for average marine plankton 1200 versus 500 and 106 respectively which may be caused by postdepositional differential decomposition of organic matter

rare earth elements in foraminifera tests abstract the concentrations of nine rare earth elements ree la ce nd sm eu gd dy er and yb have been determined in mixed species assemblages of foraminifera tests taken from atlantic ocean sediment core tops reductive cleaning techniques have revealed that ree are present in three phases in foraminifera tests collected from sea floor sediments ree included in the foraminiferal calcite matrix termed lattice ree ree associated with an authigenic femn rich phase adsorbed onto the surface of the test following the death of the organism termed coating ree and ree associated with alumino silicate detritus termed detrital ree which commonly infills the test chambers after burial in the sediment the concentrations of ree in the nondetrital lattice plus coating and lattice phases have been measured in this study approximately 90 of the ree measured in the non detrital phase reside in the coating phase the remainder being present in the lattice phase these data have been used to investigate the relationship between the distribution of dissolved ree in the ocean and in the coating and lattice phases in addition to the ree the concentrations of mn fe cu al and po4 have been measured as an aid to characterisation of the various phases

microatoll record for large century scale sea level fluctuations in the mid holocene coral microatolls have been long used as precise indicators of past sea level but their use for precise definition of detailed sea level fluctuations is still rare here we report twelve high precision thermal ionization mass spectrometric th 230 ages for twelve rims of five mid holocene microatolls from all emerged reef terrace at leizhou peninsula northern south china sea this is a tectonically stable area enabling lis to reconstruct both the timing and trajectory of local sea level fluctuations accurately the elevations of these microatoll rims and cores were accurately determined relative to the surface of modern livin microatolls at the same site the results indicate that the sea level during the period of 7050 6600 yr bp years before ad 1950 was about 171 to 219 cm above the present with at least four cycles of fluctuations over this 450 yr interval sea level fluctuated by 20 40 cm on century scales crown copyright c 2009 published by university of washington all rights reserved

inverse modeling of the hydrological and the hydrochemical behavior of hydrosystems characterization of karst system functioning inverse modeling of mass transfer characterizes the dynamic processes affecting the function of karst systems and can be used to identify karst properties an inverse model is proposed to calculate unit hydrographs as well as impulse response of fluxes from rainfall runoff or rainfall flux data the purpose of which is hydrograph separation contrary to what hydrologists have been doing for years hydrograph separation is carried out by using transfer functions in their entirety which enables accurate separation of fluxes as was explained in the companion paper pinault et al this issue the unit hydrograph as well as impulse response of fluxes is decomposed into a quick and a slow component and consequently the effective rainfall is decomposed into two parts one contributing to the quick flow or flux and the other contributing to the slow flow generation this approach is applied to seven french karstic aquifers located on the larzac plateau in the grands causses area in the south of france both hydrodynamical and hydrogeochemical data have been recorded from these springs over several hydrological cycles for modeling purposes karst properties can be represented by the impulse responses of flow and flux of dissolved species the heterogeneity of aquifers is translated to time modulated flow and transport at the outlet monitoring these fluxes enables the evaluation of slow and quick components in the hydrograph the quick component refers to the flush flow effect and results from fast infiltration in the karst conduit network when connection is established between the infiltration and phreatic zones inducing an increase in water head this component reflects flood events where flow behavior is nonlinear and is described by a very short transfer function which increases and decreases according to water head the slow component consists of slow and fast infiltration underground runoff storage in annex to drain systems and discharge from the saturated zone these components can be further subdivided by measuring chemical responses at the karst outlet using such natural tracers enables the slow component of the unit hydrograph to be separated into preevent water i e water of the reservoir and event water i e water whose origin can be related to a particular rainfall event these measurements can be used to determine the rate of water renewal since the preevent water hydrograph is produced by stored water when pushed by a rainfall event and the event water hydrograph reflects rainwater transfer separating the two components can yield insights into the characteristics of karst aquifers the modes of infiltration and the mechanisms involved in karstification as well as the degree of organization of the aquifer

using time lapse gravity for groundwater model calibration an application to alluvial aquifer storage 1 the estimation of hydrological model parameters by calibration to field data is a critical step in the modeling process however calibration often fails because of parameter correlation here it is shown that time lapse gravity data can be combined with hydraulic head data in a coupled hydrogeophysical inversion to decrease parameter correlation in groundwater models this is demonstrated for a model of riverbank infiltration where combined inversion successfully constrains hydraulic conductivity and specific yield in both an analytical and a numerical groundwater model a sensitivity study shows that time lapse gravity data are especially useful to constrain specific yield furthermore we demonstrate that evapotranspiration and riverbed conductance are better constrained by coupled inversion to gravity and head data than to head data alone when estimating the four parameters simultaneously the six correlation coefficients were reduced from unity when only head data were employed to significantly lower values when gravity and head data were combined our analysis reveals that the estimated parameter values are not very sensitive to the choice of weighting between head and gravity data over a large interval of relative weights

delta o 18 sr ca and mg ca records of porites lutea corals from leizhou peninsula northern south china sea and their applicability as paleoclimatic indicators combined seasonal to monthly resolution coral skeletal delta 18 o sr ca and mg ca records are reported for one modem and two late holocene porites lutea corals from a fringing reef at leizhou peninsula the northern coast of the south china sea scs all the profiles for the period 1989 2000 reveal annual cycles well correlated with instrumental sea surface temperatures sst and display broad peaks in summer and narrow troughs in winter reflecting seasonal growth rate variations calibration against instrumental sst yields the following equations delta 18 o 0 174 0 010 xsst degrees c 1 02 0 27 mswd 5 8 sr ca mmol mol 0 0424 0 0031 xsst degrees c 9 836 0 082 mswd 8 6 and mg ca mmol mol 0 110 0 009 xsst degrees c 1 32 0 23 mswd 55 the scatter in the mg ca sst relationship is much larger than analytical uncertainties can account for suggesting the presence of sst unrelated components in the mg ca variation calculated sr ca sst values for two later holocene porites lutea samples u series ages similar to 541 bc and similar to 487 ad respectively from the same reef suggest that sst in the scs at similar to 541 bc was nearly as warm as in the 1990s the warmest decade of the last century but at similar to 487 ad it was significantly cooler this observation is consistent with climatic data reported in chinese historic documents confirming that the sr ca sst relationship is a reliable thermometer removing the sst component in the delta 18 o variation based on calculated sr ca sst values the residual delta 18 o reflects the deviation of the holocene seawater delta 18 o from the modem value which is also a measure of the holocene sea surface salinity sss or the summer monsoon moisture level in mainland china such residual delta 18 o was close to zero at similar to 541 bc and 0 3 parts per thousand at similar to 487 ad suggesting that it was as wet as in the 1990s at similar to 541 bc but significantly drier at similar to 487 ad in mainland china which are also consistent with independent historic records calculated mg ca sst values for the two late holocene corals are significantly lower than the sr ca sst values and are also in conflict with chinese historic records suggesting that coral mg ca is not reliable proxy for sst at comparable sr ca ranges fossil corals always display negative mg ca offsets if compared with the modem coral of the same site we interpret this observation as due to preferential loss of mg during meteoric dissolution of cryptic mg calcite bearing microbialites in the exposed fossil corals microbialites mgo up to 17 sr only 100 300 ppm are ubiquitous during reef building processes and their presence in only a trace amount will have a significant impact on coral mg ca ratios without detectable influence on coral sr ca ratios c 2004 elsevier b v all rights reserved

spatial distribution of sedimentary p pools in a mediterranean coastal lagoon albufera d es grau minorca island spain the method for the sequential extraction of p proposed by jensen et al mcglathery k j marino r howarth r w 1998 limnol oceanogr 43 799 810 was used to study the spatial distribution of sedimentary p in superficial sediments of a mesohaline coastal lagoon located in a watershed formed by carboniferous sandstone in the western mediterranean minorca island spain dissolved inorganic phosphate ip dissolved organic phosphate op fe ca al and f were analyzed in the extractions to assess adequacy of this method to clay sediments the elemental composition of the solid phase al fe k ti si mg and ca was also analyzed to relate concentrations of p pools to the mineral composition samples from marine carbonated sediments rock and some materials of biological origin tubes of polychaete ficopomatus enigmaticus bivalve shell debris were analyzed for comparative purposes the sequential procedure allowed to extract almost all sedimentary p from carbonate sediments and biogenic debris but only 70 of total phosphorus tp from clay sediments and rock main ip pools in the lagoon were fe bound p 16 6 of tp caco3 bound p mainly from ficopomatus tubes 12 0 of tp and detrital carbonate fluorapatite 7 8 of tp the most abundant p pool was refractory p 20 3 of tp which appeared associated to the fe k al silicate fraction and to humic p this indicated that clay humic organic p complexes were the main p reservoir in the lagoon spatial distribution of p pools reflected differential sedimentation of allochthonous materials authigenic precipitation of fe oxides and fe bound p as well as the differential distribution of organisms such as ficopomatus

quantitative estimation of water storage and residence time in the epikarst with time lapse refraction seismic the hydrodynamic characterization of the epikarst the shallow part of the unsaturated zone in karstic systems has always been challenging for geophysical methods this work investigates the feasibility of coupling time lapse refraction seismic data with petrophysical and hydrologic models for the quantitative determination of water storage and residence time at shallow depth in carbonate rocks the biot gassmann fluid substitution model describing the seismic velocity variations with water saturation at low frequencies needs to be modified for this lithology i propose to include a saturation dependent rock frame weakening to take into account water rock interactions a bayesian inversion workflow is presented to estimate the water content from seismic velocities measured at variable saturations the procedure is tested first with already published laboratory measurements on core samples and the results show that it is possible to estimate the water content and its uncertainty the validated procedure is then applied to a time lapse seismic study to locate and quantify seasonal water storage at shallow depth along a seismic profile the residence time of the water in the shallow layers is estimated by coupling the time lapse seismic measurements with rainfall chronicles simple flow equations and the petrophysical model the daily water input computed from the chronicles is used to constraint the inversion of seismic velocities for the daily saturation state and the hydrodynamic parameters of the flow model the workflow is applied to a real monitoring case and the results show that the average residence time of the water in the epikarst is generally around three months but it is only 18 days near an infiltration pathway during the winter season the residence times are three times shorter in response to the increase in the effective rainfall

cadmium zinc copper and barium in foraminifera tests the concentrations of cadmium zinc copper and barium have been determined on 2 mg samples of single species foraminifera populations cleaning techniques were tested using north atlantic core tops and followed by a detailed downcore study for the last 30 000 years in south atlantic core v22 174 raw foram tests cleaned by crushing followed by ultrasonic removal of fine grained material and dissolved in a ph 5 5 acetate buffer contain appreciable amounts of trace elements associated with ferromanganese and alumino silicate contaminants a reductive complexing cleaning treatment reduces ferromanganese contamination by 1 2 orders of magnitude acetate buffers at ph 5 5 complex iron and raise the solubility of ferromanganese oxides these buffers are unsuitable for separating carbonate lattice bound trace elements from the fraction associated with ferromanganese phases improved mechanical and ultrasonic reductive cleaning combined with a mild dissolution in distilled water under 1 atm pco2 reduces contaminant levels another order of magnitude the cd and zn concentrations order 10 8 mole cd mole ca and 10 5 mole zn mole ca of species with low surface area show an increase with decreasing isotopic temperatures this increase is consistent with the increasing concentrations of these metals from low values in surface waters to higher values at depth the variance of cd and zn over the last 30 000 years in the central south atlantic is consistent with the probable variability of the dissolved trace elements at the calcification levels of the species analyzed cu and ba are irreproducible and probably sensitive to residual contaminant phases the trace element content of the tests differs from levels observed in a recent coprecipitation study foraminifera may be a significant vector in zinc cycling in the ocean

high frequency winter cooling and reef coral mortality during the holocene climatic optimum a detailed ecological micro structural and skeletal sr ca study of a 3 42 m thick goniopora reef profile from an emerged holocene reef terrace at the northern south china sea reveals at least nine abrupt massive goniopora stress and mortality events occurred in winter during the 7 0 7 5 thousand calendar years before present cal ka bp within the holocene climatic optimum whilst calculated sr ca sst sea surface temperature maxima during this period are comparable to those in the 1990s sr ca sst minima are significantly lower probably due to stronger winter monsoons such generally cooler winters superimposed by further exceptional winter cooling on inter annual to decadal scales may have caused stress and mortality of the corals about every 50 years sea level rose by similar to 3 42 m during this period with present sea level reached at similar to 7 3 ka bp and a sea level highstand of at least similar to 1 8 m occurred at similar to 7 0 ka the results show that it took about 20 25 years for a killed goniopora coral reef to recover c 2004 elsevier b v all rights reserved

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

separating climate induced mass transfers and instrumental effects from tectonic signal in repeated absolute gravity measurements we estimate the signature of the climate induced mass transfers in repeated absolute gravity measurements based on satellite gravimetric measurements from the gravity recovery and climate experiment grace mission we show results at the globe scale and compare them with repeated absolute gravity ag time behavior in three zones where ag surveys have been published northwestern europe canada and tibet for 10 yearly campaigns the uncertainties affecting the determination of a linear gravity rate of change range 3 4 nm s 2 a in most cases in the absence of instrumental artifacts the results are consistent with what is observed for long term repeated campaigns we also discuss the possible artifact that can result from using short ag survey to determine the tectonic effects in a zone of high hydrological variability we call into question the tectonic interpretation of several gravity changes reported from stations in tibet in particular the variation observed prior to the 2015 gorkha earthquake

paleogeodetic records of seismic and aseismic subduction from central sumatran microatolls indonesia we utilize coral microatolls in western sumatra to document vertical deformation associated with subduction microatolls are very sensitive to fluctuations in sea level and thus act as natural tide gauges they record not only the magnitude of vertical deformation associated with earthquakes paleoseismic data but also continuously track the long term aseismic deformation that occurs during the intervals between earthquakes paleogeodetic data this paper focuses on the twentieth century paleogeodetic history of the equatorial region our coral paleogeodetic record of the 1935 event reveals a classical example of deformations produced by seismic rupture of a shallow subduction interface the site closest to the trench rose 90 cm whereas sites further east sank by as much as 35 cm our model reproduces these paleogeodetic data with a 2 3 m slip event on the interface 88 to 125 km from the trench axis our coral paleogeodetic data reveal slow submergence during the decades before and after the event in the areas of coseismic emergence likewise interseismic emergence occurred before and after the 1935 event in areas of coseismic submergence among the interesting phenomenon we have discovered in the coral record is evidence of a large aseismic slip or silent event in 1962 27 years after the 1935 event paleogeodetic deformation rates in the decades before after and between the 1935 and 1962 events have varied both temporally and spatially during the 25 years following the 1935 event submergence rates were dramatically greater than in prior decades during the past four decades however rates have been lower than in the preceding decades but are still higher than they were prior to 1935 these paleogeodetic records enable us to model the kinematics of the subduction interface throughout the twentieth century

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

the phosphorus cycle phosphogenesis and marine phosphate rich deposits abstract phosphorus in the form of phosphate is an essential nutrient and energy carrier on many different levels of life and a key element in mediating between living and lifeless parts of the biosphere one of the most important aspects of the phosphorus cycle is its vital role in governing productivity thereby interacting with the exogenic part of the carbon cycle which in turn is important in regulating earth s climate phosphorus is a prime element to be traced in earth s history because it allows for the reconstruction of long term feedback mechanisms between climate environment and ecology and of global change as such marine sedimentary phosphate deposits are particularly suited to study aspects of the phosphorus cycle because in the case of ubiquity their origin may result from a general acceleration of the global phosphorus cycle sources of sedimentary phosphate are microbial breakdown of buried organic matter and redox driven phosphate desorption from iron and manganese oxyhydroxides dissolved sea water phosphate represents an additional source which may become important in the formation of phosphatic hardgrounds the main locus of phosphogenesis is near the sediment water interface but phosphogenesis also occurs at greater sediment depths current induced winnowing and transport processes along the sea floor concentrate phosphate precipitates into deposits which exhibit internal stratification patterns typical for the prevailing hydraulic energy regime in a sequence stratigraphic context phosphate deposits preferentially occur along marine or maximum flooding surfaces consequent sedimentary reworking may result in the transfer of phosphates to highstand or lowstand deposits bio chemical weathering on continents represents the most significant source of bioavailable phosphorus this implies that long term changes in marine phosphorus levels and with these changes in marine ecology productivity rates and ratios of exported carbonate carbon and organic carbon are a response to changes in continental weathering rates a compilation of marine sedimentary phosphorus burial rates for the last 160 myr suggests that natural variations have occurred that span one order of magnitude for the late jurassic cretaceous and most of the paleogene the phosphorus cycle appears to have been accelerated in times of climate warming which was most likely due to the spreading of zones of humid climate and more intense continental weathering in the neogene the phosphorus cycle appears to have responded to changes in glacially induced weathering this suggests that uniform interpretations with respect to the emplacement of major phosphorite deposits should be treated with caution integrated analyses of the sedimentary and biogeochemical context of phosphorite occurrences may help to identify paleoenvironmental conditions as well as to improve our understanding of periods of enhanced phosphate accumulation periods which were usually characterized by steep gradients in the development of climate and environment with regard to the complexity of feedback mechanisms between the phosphorus cycle and the biosphere the present day input rates of phosphate into the world s oceans should be of great concern they are more than doubled by anthropogenic means and affect ecological systems on a rapidly increasing scale

significance of shallow core transects for reef models and sea level curves heron reef great barrier reef a sequence of shallow reef cores from heron reef great barrier reef provides new insights into holocene reef growth models isochron analysis of a leeward core transect suggests that the north western end of heron reef reached current sea level by ca 6 5 kyr bp and then prograded leeward at a rate of ca 19 6 m kyr between 5 1 kyr and 4 1 kyr bp pre 1950 to the present reef margin a single short core on the opposing margin of the reef is consistent with greater and more recent progradation there further to the east one windward core reached modern sea level by ca 6 3 kyr bp suggesting near keep up behaviour at that location but the opposing leeward margin behind the lagoon reached sea level much more recently hence heron reef exhibited significantly different reef growth behaviour on different parts of the same margin mean reef accretion rates calculated from within 20 m of one another in the leeward core transect varied between ca 2 9 m and 4 7 m kyr depending on relative position in the prograding wedge these cores serve as a warning regarding the use of isolated cores to inform reef growth rates because apparent aggradation at any given location on a reef varies depending on its location relative to a prograding margin only transects of closely spaced cores can document reef behaviour adequately so as to inform reef growth models and sea level curves the cores also emphasize potential problems in u series dates for corals within a shallow ca 1 5 m zone beneath the reef flat apparent age inversions restricted to that active diagenetic zone may reflect remobilization and concentration of th in irregularly distributed microbialites or biofilms that were missed during sample vetting importantly the th containing contaminant causes ages to appear too old rather than too young as would be expected from younger cement

sedimentary phosphorites an example phosphoria formation southeastern idaho u s a the phosphorous cycle filters through both the biological and geological worlds and sedimentary phosphates exist at the interface between these two portions of the global phosphorous cycle sedimentary phosphates form only when the proper physical conditions and biological activity coincide once deposited the phosphate po43 crystallizes into the mineral carbonate fluorapatite cfa this mineral with substitution of co32 for po43 compositionally falls between the familiar forms of fluorapatite found in igneous and metamorphic rocks and the apatites found in biological material including our own bones and teeth finally through mining and processing it is these sedimentary phosphates that are used as fertilizers and additives for food production and other activities and are subsequently returned to the biosphere the unique settings in which phosphorites form those areas where phosphate is concentrated millions of times above normal and sedimentation rates are drastically slowed are not fully understood and have been the subject of sometimes intense scientific debate over the last century and a half furthermore the mineralogy of these deposits is unique difficult to study and contentious because of our dependence on phosphate for use in fertilizers and other agricultural and chemical uses these deposits are interesting not only from a scientific viewpoint but from an economic standpoint as well however like many mining operations phosphate mining has environmental problems that must be addressed this chapter provides an overview of the salient points in phosphorite formation mineralogy and mining and puts into context the current work being undertaken on the phosphoria formation in southeastern idaho this chapter does not provide a full description of all the sedimentalogical mineralogical and industrial work that has been done on sedimentary phosphates indeed numerous full volumes have been published on phosphorites and more will undoubtedly follow for large scale phosphorites to

authigenic apatite formation and burial in sediments from non upwelling continental margin environments abstract evidence for precipitation of authigenic carbonate fluorapatite cfa in long island sound and mississippi delta sediments suggests that formation of cfa is not restricted to environments of active coastal upwelling we present porewater data suggestive of cfa formation in both these areas application of a sequential leaching procedure designed specifically to separate authigenic carbonate fluorapatite from other phosphorus containing phases including detrital apatite of igneous or metamorphic origin provides strong supporting evidence for authigenic apatite formation in these sediments the size of the authigenic apatite reservoir increases with depth indicating continued formation of cfa during early diagenesis this depth increase is mirrored by a decrease in solid phase organic p at both sites suggesting that cfa is forming at the expense of organic p mass balance considerations application of diagenetic models to interstitial water nutrient data and the saturation state of the interstitial water are consistent with this interpretation diagenetic redistribution of phosphorus among the different solid phase reservoirs is observed at both sites and results in near perfect retention of p by these sediments over the depth intervals sampled formation of cfa in continental margins which do not conform to the classically defined regions of phosphorite formation renders cfa a quantitatively more important sink than has previously been recognized including this reservoir as a newly identified sink for reactive p in the ocean the residence time of p in the modern ocean must be revised downward the implication for ancient oceans of cfa formation in continental margin sediments other than phosphorites is that phosphorite formation may be less a representation of episodicity in removal of reactive p from the oceans than of localized concentration of cfa in phosphatic sediments by secondary physical processes

francolite authigenesis in california continental slope sediments and its implications for the marine p cycle abstract authigenesis of francolite carbonate fluorapatite in continental slope sediments may represent the most important oceanic sink for reactive p we infer from sedimentary p speciation and pore fluid fluoride concentrations that francolite currently forms in holocene sediments on the california continental slope authigenic p accumulation rates range from 0 006 to 0 089 mol cm 2 yr and dissolved fluoride uptake rates range from 0 004 to 0 039 mol cm 2 yr these two independent parameters correlate positively with each other among all sites r 2 0 77 and the slope of their linear relationship gives a p f molar ratio of 2 4 a typical value for authigenic francolite our results imply that active francolite authigenesis sequesters nearly 30 of the remobilized organic and fe bound p at shallow burial depths in california continental slope sediments assuming that similar processes occur globally we estimate that francolite authigenesis in near surface continental slope sediments may account for a burial flux of 1 4 1 0 10 10 mol p yr or 8 to 48 of the global input flux of reactive p to the ocean

two hundred thirty years of relative sea level changes due to climate and megathrust tectonics recorded in coral microatolls of martinique french west indies we sampled six coral microatolls that recorded the relative sea level changes over the last 230 years east of martinique on fringing reefs in protected bays the microatolls are cup shaped which is characteristic of corals that have been experiencing submergence x ray analysis of coral slices and reconstructions of the highest level of survival hls curves show that they have submerged at rates of a few millimeters per year their morphology reveals changes in submergence rate around 1829 11 1895 and 1950 tide gauges available in the region indicate a regional sea level rise at a constant mean rate of 1 1 0 8 mm yr which contrasts with our coral record implying additional tectonic subsidence comparing our coral morphology with that of synthetic corals generated with matlab by using the key west tide gauge record florida we show that their growth was controlled by tectonics and that a sudden relative sea level increase drowned them around 1950 simple elastic models show that this sudden submergence probably occurred during the 21 may 1946 earthquake which ruptured the plate interface in front of martinique in the mantle wedge in an area of sustained seismic activity the 1839 m8 earthquake probably occurred in the same area long term subsidence of microatolls indicates that this deep portion of the megathrust is probably locked down to 60 km depth during the interseismic period our oldest coral recorded a long lasting period 50 years of stable relative sea level after the 1839 earthquake indicating that transient interseismic strain rate variations may occur in the lesser antilles

far field test of the ice 4g model of global isostatic response to deglaciation using empirical and theoretical holocene sea level reconstructions for the fiji islands southwestern pacific holocene paleosea level data for fiji represented by 77 dates and emergence magnitudes are presented screened and adjusted most data are from coral microatolls potentially the most precise paleosea level indicators in this region holocene sea level changes are reconstructed for five areas within fiji known to have had different late quaternary tectonic histories resulting analysis suggests that postglacial sea level in fiji reached its present level more than 6900 14c yr b p it also suggests either that a single maximum 5650 3200 14c yr b p perhaps 2 19 m but more likely 1 35 1 50 m occurred or that two maxima occurred 6100 4550 14c yr b p 0 75 1 85 m and 3590 2800 14c yr b p 0 90 2 46 m broad agreement exists between these empirical sea level reconstructions and those derived theoretically using the ice 4g model predicted maximum 4000 14c yr b p 2 1 m this suggests that both methods of reconstructing holocene sea level changes are valid as are the assumptions underpinning the ice 4g model the most important of these that eustatic sea level had effectively stopped rising by late middle holocene time 5000 4000 yr b p is confirmed by observations from fiji

a novel chemical method to quantify fish debris in marine sediments burial of fish bones which consist primarily of hydroxyapatite has been recognized as a mechanism to remove reactive phosphorus from the oceans in this study a new method is presented which differentiates p associated with biogenous apatite pfish from other p fractions the method consisting of a sequential chemical extraction with 2 m nh4cl has been successfully tested on standard materials it enables us for the first time to quantify fish debris in sediment records and to assess their importance for the marine phosphorus cycle the nh4cl extraction has been applied to sediment samples from the arabian sea preservation of fish debris is significantly higher in sediments located above 1 200 m water depth than it is for deeper sediments the distribution of pfish contents in surface sediments is predominantly governed by the extent of fish debris regeneration which is related to differences in water depth and sedimentation rates in addition a good correlation between high sedimentary pfish contents and low oxygen bottom water concentrations suggests that the presence of the intense oxygen minimum zone may account for the enhanced preservation of fish debris in continental slope sediments

on the impact of topography and building mask on time varying gravity due to local hydrology we use 3 yr of surface absolute gravity measurements at three sites on the larzac plateau france to quantify the changes induced by topography and the building on gravity time series with respect to an idealized infinite slab approximation indeed local topography and buildings housing ground based gravity measurement have an effect on the distribution of water storage changes therefore affecting the associated gravity signal we first calculate the effects of surrounding topography and building dimensions on the gravity attraction for a uniform layer of water we show that a gravimetric interpretation of water storage change using an infinite slab the so called bouguer approximation is generally not suitable we propose to split the time varying gravity signal in two parts 1 a surface component including topographic and building effects 2 a deep component associated to underground water transfer a reservoir modelling scheme is herein presented to remove the local site effects and to invert for the effective hydrological properties of the unsaturated zone we show that effective time constants associated to water transfer vary greatly from site to site we propose that our modelling scheme can be used to correct for the local site effects on gravity at any site presenting a departure from a flat topography depending on sites the corrected signal can exceed measured values by 5 15 gal corresponding to 120 380 mm of water using the bouguer slab formula our approach only requires the knowledge of daily precipitation corrected for evapotranspiration therefore it can be a useful tool to correct any kind of gravimetric time series data

hydrogeological investigations at the membach station belgium and application to correct long periodic gravity variations 1 a comprehensive hydrogeological investigation regarding the influence of variations in local and regional water mass on superconducting gravity measurements is presented for observations taken near the geodynamic station of membach belgium applying a regional water storage model the gravity contribution due to the elastic deformation of the earth was derived in addition the newtonian gravity effect induced by the local water mass variations was calculated using soil moisture observations taken at the ground surface about 48 m above the gravimeters the computation of the gravimetric effect is based on a digital elevation model with spatially discretized rectangular prisms the obtained results are compared with the observations of a superconducting gravimeter sg we find that the seasonal variations can be reasonably well predicted with the regional water storage model and the local newtonian effects shorter period effects depend on the local changes in hydrology this result shows the sensitivity of sg observations to very local water storage changes

manganese carbonate overgrowths on foraminifera tests below the zone where manganese is remobilized as mn2 aq reductively cleaned foraminifera in deep sea sediments have much higher mnca than those in core tops and sediment traps mnca ranges from less than 20 10 6 in and above the mno2 maximum to as high as 700 10 6 in reducing panama basin sediments the most plausible explanation for this enrichment is that the tests are coated with mn carbonate overgrowths these coatings can account for a significant proportion of the mn in reduced deep sea sediments uptake of manganous ion by carbonate may explain the absence of mn nodules in areas of high carbonate accumulation extreme degrees of overgrowth can alter foram trace element values but this artifact can be avoided by avoiding foraminifera with high mn ca

tertiary paleoceanic chemical variability unintended consequences of simple geochemical models five lines of concrete quantitative evidence about oceanic chemical composition during the past 65 m y can provide insights into the controlling processes and their temporal variations but the system constraints are not yet fully understood the calcium carbonate compensation depth mean carbon isotopic ratio and strontium isotopic ratio have all changed significantly during this time while changes in lithium to calcium and strontium to calcium ratios have been much smaller when these tracers are considered separately simple scenarios of changes in geochemical and geological factors can be used to explain the historical records these factors include 1 increases in continental chemical weathering rates and net continental fluxes to the oceans 2 changes in the isotopic composition of material weathered from continents to the oceans 3 decreases in the proportion of calcium carbonate deposited on continental shelves 4 changes in the deposition or weathering rates of certain types of sediments and 5 changes in hydrothermal circulation because these geochemical cycles are linked to each other and to others such as nutrients and global atmospheric carbon dioxide an explanation invoked for one tracer must satisfy the direction magnitude and timing of the patterns for all the tracers several simple scenarios for geochemical variations have been evaluated for their consequences both intended and unintended and compared to the historical records despite the attractiveness and possible justifications of some simple hypotheses for example decreases in organic carbon burial rates increases in carbonate weathering rates on the continents or increases in all continental weathering rates no one simple scenario appears to be consistent with both the timing and magnitude of the changes observed during the past 65 m y for all tracers considered the contradictions uncovered can be useful in defining what knowledge is crucial to further understanding of oceanic chemical history better knowledge is needed of absolute deep ocean sediment accumulation rates and their temporal variability of the extent and time scale of variability in the net carbon isotope input to the ocean from continental weathering of steady state fluxes for oceanic mass balances and the extent to which these mass balances approach steady state behavior and of the links and interactions between the geochemical cycles of various elements

modern vertical deformation above the sumatran subduction zone paleogeodetic insights from coral microatolls coral microatolls from the coast and outer arc islands of western sumatra retain a stratigraphic and morphologic record of relative sea level change which is due in large part to vertical tectonic deformation above the sumatran subduction zone low water levels whose fluctuations produce measurable changes in coral morphology limit the upward growth of the microatolls annual rings derived from seasonal variations in coral density serve as an internal chronometer of coral growth the microatolls act as natural long term tide gauges recording sea level variations on time scales of decades field observations and stratigraphic analysis of seven microatolls five from the outer arc islands and two from the mainland coast indicate that the mentawai islands have been submerging at rates of 4 10 mm yr over the last four or five decades while the mainland has remained relatively stable the presence of fossil microatolls up to several thousand years old in the intertidal zone indicates that little permanent vertical deformation has occurred over that time thus most of the strain accumulated in the past few decades represents interseismic deformation that is recovered during earthquakes elastic dislocation models using these submergence data suggest that elastic strain is being accumulated in the interseismic period and that the subduction zone in this region is fully coupled

analysis of partially emerged corals and reef terraces in the central vanuatu arc comparison of contemporary coseismic and nonseismic with quaternary vertical movements in the central vanuatu arc living and recently deceased reef corals act as natural tide gauges which have allowed us to map vertical tectonic deformation patterns as corals grow the density of the aragonite coral skeletons varies on an annual cycle producing annual growth bands similar to tree rings using coral growth bands we can determine the year coral surfaces died due to emergence we interpret four major coral emergence events as coseismic uplifts that occurred near the epicenters and times of large shallow earthquakes on january 5 1946 ms 7 3 august 11 1965 ms 7 5 october 27 1971 ms 7 1 and december 29 1973 ms 7 5 the 1965 and 1973 events caused maximum uplifts of 120 and 60 cm respectively in the frontal arc also related to these events are uplifts of 10 cm and 6 cm in the back arc on pentecost and maewo islands which lie east of the volcanic chain and the primary forearc zones of uplift and subsidence similar secondary zones of uplift occurred with the great 1960 chile and 1964 alaska earthquakes the amplitude of these secondary uplifts is significantly larger than that predicted by models having a single fault in an elastic half space however the amount of secondary uplift is comparable to that predicted if the fault occurs in a plate of constant thickness overlying a viscoelastic half space at various places in 1957 1969 1970 1977 and 1978 1981 there was about 5 10 cm of emergence not associated with major earthquakes which may indicate nonseismic tectonic uplift however oceanographically lowered sea levels as in el ninos may have determined the times when corals died and recorded these events nevertheless the accumulation of emergence its persistence the limited geographic extent of each event and occurrence in areas of rapid holocene uplift suggest that the causes of the uplifts are tectonic these events suggest that in some areas a third or more of the total accumulated uplift in central vanuatu takes place as aseismic motion however in some areas we find only coseismic emergence in central vanuatu contemporary coseismic vertical deformation holocene uplift and topography have remarkably similar patterns this suggests that the mechanisms and processes causing vertical deformation have varied little over the last 106years apparently the topography structure and seismotectonics are controlled by the subduction of the d entrecasteaux ridge a major bathymetric feature underthrusting this part of the arc the influence of this ridge may have been especially extensive because it migrates very slowly along the arc trend and thus it interacts for a long time with a single portion of the arc system our previous studies of reef terraces indicated the existence of at least four seismotectonic arc segments or blocks along the santo malekula interval of the arc and our present results further support this conclusion each block has uplifted at different times by different amounts at different rates and tilted in a different direction boundaries between the north santo and the south santo segment and between the north malekula and the south malekula segment correlate with the north and south flanks of the d entrecasteaux ridge as does the absence of a physiographic trench west of santo

on the inclusion of ground based gravity measurements to the calibration process of a global rainfall discharge reservoir model case of the durzon karst system larzac southern france thiswork examines the relevance of the inclusion of ground based gravity data in the calibration process of a global rainfall discharge reservoir model the analysis is performed for the durzon karst system larzac france the first part of the study focuses on the hydrological interpretation of the ground based gravity measurements the second part of the study investigates further the information content of the gravity data with respect to water storage dynamics modelling the gravity derived information is found unable to either reduce equifinality of the single objective dischargebased model calibration process or enhance model performance through assimilation

phosphorus accumulation in marine sediments and the oceanic phosphorus cycle ideas about key factors in the oceanic mass balance of dissolved reactive phosphate have changed substantially i present an integrated overview of these here with an emphasis on evaluating the burial sinks for p and defining areas needing further research the major source of reactive p to the ocean is river input reactive p is delivered to the oceanic sediment water interface primarily in particulate organic matter p scavenged by hydrothermal iron rich oxyhydroxide particles with uptake in proportion to deep water phosphate concentrations represents a substantially smaller flux to the sediment water interface diagenetic transformations are important influences on the form of reactive p burial in marine sediments p burial occurs with organic carbon burial and as p associated with iron rich oxyhydroxide particles and coatings formation of authigenic p rich phases presumably apatite at the expense of organic p and oxide associated p is significant in open ocean marine sediments the authigenic p sink may represent a substantially larger portion of the sedimentary burial than indicated by previous estimates focused on p burial in organic rich continental margin sediments

seasonal effect on vertical positioning by satellite laser ranging and global positioning system and on absolute gravity at the oca geodetic station grasse france summary we present a comparison of the vertical displacement monitored by independent techniques at the geodetic observatory of grasse france both satellite laser ranging and global positioning system gps vertical position time series over the period 1998 2003 show a prominent annual signal with a magnitude of 5 6 mm and reaching a maximum every year in july results from 14 absolute gravity measurements are also discussed we investigate the possible origin of the observed signal by comparing it with predictions from various local and regional contributions gps results from a local network indicate that the periodic annual elastic deformation of the 1270 m high karstic plateau due to local water storage loading does not exceed 1 2 mm in contrast a combination of global model prediction for atmospheric and hydrological loading explains more than 70 per cent of the annual and semi annual observed signals

local and global hydrological contributions to time variable gravity in southwest niger p advances in methods of observation are essential to ensure a better understanding of changes in water resources considering climate variability and human activities the ghyraf gravity and hydrology in africa experiments aim to combine gravimetric measurements with dense hydrological surveys to better characterize the annual water storage variability in tropical west africa the first absolute gravimetric measurements were performed in southwest niger near a temporary pond where rapid infiltration to an unconfined aquifer occurs as gravity is sensitive both to local and global variations of water mass distribution the large scale hydrological contribution to time variable gravity has been removed using either grace satellite data or global hydrology models the effect of the local water storage changes was modelled using in situ measurements of the water table soil moisture and pond water level the adjustment of these simulations to residual ground gravity observations helped to constrain the specific yield to a value ranging between 1 8 and 6 2 per cent this range of value is consistent albeit on the low side with the aquifer water content 6 12 per cent estimated by magnetic resonance soundings which are known to slightly overestimate the specific yield in this geological context the comparison of these two independent geophysical methods shows their potential to constrain the local hydrogeological parameters besides this study evidences the worth of correcting the gravity signal for large scale hydrology before recovering local water storage parameters

a master of the earth h d holland and his contributions to geochemistry abstract h d holland was one of the great geochemists of modern times as a professor at princeton university for 22 years and at harvard for 33 he mentored 24 graduate students and 24 postdoctoral researchers he was a member of the u s national academy of sciences and a president of the geochemical society he co authored 179 publications in 64 years from 1949 to 2012 including four books he edited one other book and with karl turekian co edited the ten volume treatise on geochemistry his contributions to geochemistry were mainly in economic geology hydrothermal processes and especially the chemistry and evolution of the earth s atmosphere and oceans a topic to which he devoted nearly half of his publications his most significant contributions documented changes in the composition of seawater through geologic time and the rise of oxygen in earth s atmosphere he pioneered the use of mineral sequences in marine evaporite deposits and fluid inclusions in evaporite minerals to determine the composition of ancient seawater he collected extensive data on paleosols and used them to calibrate the oxygen content of the ancient atmosphere documenting its rise in the great oxidation event that peaked between 2 41 and 2 32 ga and writing extensively about the causes of this event one of the most significant in earth history

processes controlling forms of phosphorus in surficial sediments from the eastern arabian sea impinged by varying bottom water oxygenation conditions abstract the surficial sediments from the upper continental slope of the eastern arabian sea impinged by the oxygen minimum zone omz 150 1200 m water depth show varying concentrations of the biogenic element phosphorus p 0 1 0 2 in the northern and southern areas even though total organic carbon concentrations are relatively constant toc 2 5 prakash babu et al 1999 to understand this discordance 17 surface sediment samples from shelf slope and deep sea of the eastern arabian sea were investigated using a five step sequential extraction scheme to delineate the process responsible for p enrichment in omz high fractions of organic phosphorus porg 10 26 biogenic phosphorus pbio 36 48 relatively low molar corg porg ratios 322 447 and corg preactive ratios close to redfield ratio in omz sediments of the se arabian sea suggest accumulation under high surface production and low residence time of labile forms of p due to high sedimentation rates despite higher productivity in surface waters low fractions of porg 8 13 less than deep sea sediments of the study area 12 13 pbio 25 33 relatively high molar corg porg ratios 341 508 and corg preactive ratios less than redfield ratio in omz sediments from the ne arabian sea may indicate a higher degree of regeneration and diagenetic transformation of labile forms of p to other phases authigenic phosphorus paut fraction varies by a factor of 2 8 in sediments from the omz when compared to well oxygenated deep sea sediments of the study area while the ptotal remains constant significant p transformation seems to occur in ne arabian sea which is suggested by high paut fraction 50 compared to low paut fraction 10 39 in the se arabian sea sediments supply rates of phosphorus variable rates of p dissolution under varying dissolved oxygen contents in the bottom waters and early diagenetic transformation of p within the sediments seem to influence p geochemistry in sediments overlain by the omz in the eastern arabian sea

reassessment of the oceanic residence time of phosphorus phosphorus p is an essential nutrient for the growth of all organisms and is believed to limit marine productivity especially on geologic time scales holland 1984 smith 1984 howarth 1988 codispoti 1989 as a result of the link between marine photosynthetic productivity and atmospheric co2 phosphorus along with other nutrients present in short supply in the euphoric zone have been cited as potential players in the ocean s role in climate change this link has been referred to as the nutrient co2 connection broecker 1982 model simulations which aim to quantify the role of oceanic nutrient inventories in promoting or enhancing climate change rely on the most currently formulated element budgets for the ocean in this paper significant modifications to the currently accepted marine phosphorus budget are proposed the modified p budget presented here requires a reassessment of phosphorus residence time in the ocean and a concomitant review of the role of p as a potential player in climate change over glacialinterglacial time scales element budgets constructed for the oceans consist of a mass balance between inputs and outputs for which the simplifying assumption is generally made that the ocean is in steady state with the specific element in question the fluvial p flux constitutes the bulk of the input term for the marine phosphorus budget atmospheric input is 10 of the fluvial input froelich et al 1982 burial with sediments is the mechanism for ultimate removal of p from the oceans for a system at steady state the input flux equals the output flux in the present paper we focus on the output flux burial with sediments for two reasons first the chemistry of phosphorus buried in sediment cores from which p burial fluxes are calculated has not been affected to the same degree as rivers by anthropogenic perturbation it is therefore simpler to quantify the output term of the p budget which can be extrapolated to pre anthropogenic times second detailed p speciation data permit us to quantify the burial flux of reactive p as contrasted with refractory p in sediments this distinction is significant because burial of reactive p constitutes removal of potentially bio available p from the oceans two types of modification to the marine phosphorus budget are proposed here first the locus of p burial is addressed specifically the importance of p burial in the deep sea is contrasted with p burial in continental margins second the burial flux is characterized in terms of reactive potentially bio available p vs refractory p this distinction is made possible by obtaining detailed p speciation data from application of the sedex method ruttenberg 1992 a selective leaching procedure which separates solid phase p into five reservoirs on the basis of chemical reactivity loosely sorbed p ferric iron bound p authigenic apatite biogenic apatite c a c o 3 bound p detrital apatite p and organic p detailed p spe

benthic phosphorus regeneration net primary production and ocean anoxia a model of the coupled marine biogeochemical cycles of carbon and phosphorus we examine the relationships between ocean ventilation primary production water column anoxia and benthic regeneration of phosphorus using a mass balance model of the coupled marine biogeochemical cycles of carbon c and phosphorus p the elemental cycles are coupled via the redfield c p ratio of marine phytoplankton and the c p ratio of organic matter preserved in marine sediments the model assumes that on geologic timescales net primary production in the oceans is limited by the upwelling of dissolved phosphorus to the photic zone the model incorporates the dependence on bottom water oxygenation of the regeneration of nutrient phosphorus from particulate matter deposited at the water sediment interface evidence from marine and lacustrine settings modern and ancient demonstrates that sedimentary burial of phosphorus associated with organic matter and ferric oxyhydroxides decreases when bottom water anoxia dysoxia expands steady state simulations show that a reduction in the rate of thermohaline circulation or a decrease of the oxygen content of downwelling water masses intensifies water column anoxia dysoxia and at the same time increases surface water productivity the first effect reflects the declining supply of oxygen to the deeper parts of the ocean the second effect is caused by the enhanced benthic regeneration of phosphorus from organic matter and ferric oxyhydroxides sedimentary burial of organic carbon and authigenic calcium phosphate mineral francolite on the other hand is promoted by reduced ocean ventilation according to the model global scale anoxia dysoxia leads to a more efficient recycling of reactive phosphorus within the ocean system consequently higher rates of primary production and organic carbon burial can be achieved even when the continental supply of reactive phosphorus to the oceans remains unchanged

variation of initial 230th 232th and limits of high precision u th dating of shallow water corals one hundred eighty u th data including 23 isochrons on 24 pristine modern and holocene corals and 33 seawater samples were analyzed using sector field mass spectrometry to understand the variability of initial 230th 232th 230th 232th0 this dataset allows us to further assess the accuracy and precision of coral 230th dating method by applying quality control including careful sampling and subsampling protocols and the use of contamination free storage and workbench spaces the resulting low procedural blanks give an equivalent uncertainty in age of only 0 2 0 3 yr for 1 2 g of coral sample using site specific 230th 232th0 values or isochron techniques our study demonstrates that corals with an age less than 100 yrs can be 230th dated with precisions of 1 yr six living subtidal coral samples were collected from two continental shelf sites nanwan off southern taiwan in the western pacific and son tra off central vietnam in the south china sea one coral core was drilled from an open ocean site santo island vanuatu in the western tropical pacific and modern and fossil intertidal coral slabs 17 in total were cut from six sites around the islands of simeulue lago north pagai and south pagai of sumatra in the eastern indian ocean the results indicate that the main source of thorium is the dissolved phase of seawater with variation of 230th 232th0 depending on local hydrology with intense input of terrestrial material low 230th 232th0 atomic ratios of 4 9 10 6 and 3 2 10 6 with a 10 variation are observed in nanwan and son tra respectively at the santo site we find a value of 5 6 10 6 at 4 horizons and one high value of 24 10 6 in a sample from ad 1974 6 0 5 likely due to the upwelling of cold water during a la nina event between ad 1973 and 1976 the natural dynamics of 230th 232th0 recorded in the intertidal corals at sites in the sumatran islands are complicated so that this value varies significantly from 3 0 to 9 4 10 6 three of the 141 modern coral 230th ages differ from their true ages by 23 to 4 indicating the presence of detrital material with anomalous 230th 232th values duplicate measurement of coeval subsamples is therefore recommended to verify the age accuracy this improved high precision coral 230th dating method raises the prospects of refining the age models for band counted and tracer tuned chronologies and of advancing coral paleoclimate research

thermal ionization mass spectrometry u series dating of a hominid site near nanjing china mass spectrometric u series dating of speleothems from tangshan cave combined with ecological and paleoclimatic evidence indicates that nanjing man a typical homo erectus morphologically correlated with peking man at zhoukoudian should be at least 580 k y old or more likely lived during the glacial oxygen isotope stage 16 similar to 620 ka such an age estimate which is similar to 270 ka older than previous electron spin resonance and alpha counting u series dates has significant implications for the evolution of asian h erectus dentine and enamel samples from the coexisting fossil layer yield significantly younger apparent ages that of the enamel sample being only less than one fourth of the minimum age of nanjing man this suggests that u uptake history is far more complex than existing models can handle as a result great care must be taken in the interpretation of electron spin resonance and u series dates of fossil teeth

contribution of magnetic resonance soundings for characterizing water storage in the unsaturated zone of karst aquifers understanding the role of the unsaturated zone in aquifer recharge and contaminant attenuation processes is a major challenge for the protection and management of karstic water resources we present the potential of the magnetic resonance soundings mrs geophysical method for characterizing the vadose zone of karst aquifers composed of epikarst and infiltration layers to investigate the hydraulic functioning of the durzon karst system located on the larzac plateau southern france we used the mrs method at 16 sites the mrs results have been compared with available geologic information and to core water content measurements the remarkable spatial variability of the mrs response observed in the study area makes it possible to determine ranges of water storage properties in relation to the lithology of the investigated carbonate formations dolomite marly and siliceous limestone all soundings found either constant or increasing mrs water content with depth which demonstrates that the infiltration zone might be the major water storage entity for permanent water storage with important consequences for recharge quality and quantity these results show the feasibility and potential of the mrs method for the characterization of the karst unsaturated zone and for understanding the vertical distribution of water content which impacts the overall functioning of karst systems read more http library seg org doi 10 1190 geo2015 0411 1

significance of emerged holocene corals around ovalau and moturiki islands fiji southwest pacific abstract the volcanic islands ovalau and moturiki in central fiji have been subsiding very slowly for most of the past few thousand years and thus have potential for helping define holocene eustatic changes in this otherwise tectonically active region dates from fossil microatolls porites spp emerged above the modern reef flats around these islands indicate such changes ten dates from around ovalau are presented they indicate a general fall of sea level from a high 1 6 m above its present level within the period 6000 3000 yr bp the dates are readily divisible into discrete vertical groups which may indicate the inability of some reefs to reach lowest astronomical tide level as they commonly do where freshwater plumes enter the ocean alternatively the vertical separation of dates may indicate rapid transgressive regressive oscillations the distribution of dates is also characterized by a temporal hiatus of about 1000 years around 4200 yr bp which can be explained as a result of a either a rapid sea level fall around this time b a series of prolonged low sea level episodes associated with an increased frequency of el nino events or c increased nearshore deposition of terrigenous sediment perhaps associated with an increased tropical cyclone frequency or early human impact

global inter annual gravity changes from grace early results 1 fifteen monthly gravity field solutions from the grace twin satellites launched more than two years ago have been studied to estimate gravity field changes between 2002 and 2003 the results demonstrate that grace is capable of capturing the changes in ground water on inter annual scales with an accuracy of 0 4 gal corresponding to 9 mm water thickness on spatial scales longer than 1300 km four of the most widely used global hydrological models have been investigated for their spatial comparison with grace observations of inter annual gravity field variations due to changes in continental water storage the global land data assimilation system model has a spatial correlation coefficient with grace observations of 0 65 over the northern hemisphere this demonstrates that the observed gravity field changes on these scales are largely related to changes in continental water storage

microatolls as sea level indicators on a mid ocean atoll microatolls are discoid corals with flat upper surfaces that develop when upward coral growth is constrained by exposure at low tide they have been widely viewed as important and relatively precise indicators of modern and paleo sea level positions because of their sensitivity to the water air interface though this has rarely been directly established by survey to a precise datum this study involved an accurate survey of 282 microatolls growing in a range of intertidal environments open reef flats interisland passages lagoons across the cocos keeling islands a mid ocean atoll in the indian ocean the upper surface elevation of modern microatolls was found to vary through more than 40 cm across the environments in which these corals occur on cocos representing more than 30 of the spring tide range much of the variation reflects subtle ponding at low water levels across extensive low gradient reef surfaces associated with interisland passages microatolls in open reef flat habitats are typically constrained within the narrowest and most consistent elevation range around the atoll the environment in which individual fossil microatolls occurred when they were alive is significant in reconstructing former sea levels

results from parallel observations of superconducting and absolute gravimeters and gps at the hsinchu station of global geodynamics project taiwan few mm a 1 of horizontal and vertical motions around hs the calibration factor and driftingrateoft48are 75 96 0 07mgalv 1 and0 2 0 7mgala 1 1mgal 10 8 ms 2 both the sg and absolute gravity records contain trends of about 2 3 mgal a 1 the ocean tide gravity effects otges were estimated from nao 99b fes2004 and csr4 0 and their amplitudes agree with the sg observations at the submicrogal level but their phasesdifferfromtheobservationsupto10 thenewtonianeffectofoceantidecontributes 20 to the total otge at hs and it is larger at islands in the taiwan strait the inelastic body tide model of dehant et al 1999 is more consistent with the sg observations than the elastic model modeled gravity atmosphere admittances based on an exponential distribution of air mass explain well the observed admittances the average gravityatmosphere admittance during typhoons is 30 larger than that in a nontyphoon time a list of coseismic gravity changes from t48 caused by earthquakes over 2006 2007 is given for potential studies of fault parameters the modeled effects of atmospheric pressure groundwater soil moisture and polar motion explain the fg5 observed gravity trend to 1 1 mgal a 1 seasonally the groundwater induced gravity change contributes the most

seawater nutrient and carbonate ion concentrations recorded as p ca ba ca and u ca in the deep sea coral desmophyllum dianthus as paleoceanographic archives deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating but have not been fully investigated for geochemical reconstructions of past ocean conditions here we assess the utility of skeletal p ca ba ca and u ca in the deep sea coral d dianthus as proxies of dissolved phosphate remineralized at shallow depths dissolved barium trace element with silicate type distribution and carbonate ion concentrations respectively measurements of these proxies in globally distributed d dianthus specimens show clear dependence on corresponding seawater properties linear regression fits of mean coral element ca ratios against seawater properties yield the equations p cacoral lmol mol 0 6 0 1 p casw lmol mol 23 18 r 2 0 6 n 16 and ba cacoral lmol mol 1 4 0 3 ba casw lmol mol 0 2 r 2 0 6 n 17 no significant relationship is observed between the residuals of each regression and seawater temperature salinity pressure ph or carbonate ion concentrations suggesting that these variables were not significant secondary dependencies of these proxies four d dianthus specimens growing at locations withoarag 6 0 6 displayed markedly depleted p ca compared to the regression based on the remaining samples a behavior attributed to an undersaturation effect these corals were excluded from the calibration coral u ca correlates with seawater carbonate ion u cacoral lmol mol 0 016 0 003 co 2 3 lmol kg 3 2 0 3 r 2 0 6 n 17 the residuals of the u ca calibration are not significantly related to temperature salinity or pressure scatter about the linear calibration lines is attributed to imperfect spatialtemporal matches between the selected globally distributed specimens and available water column chemical data and potentially to unresolved additional effects the uncertainties of these initial proxy calibration regressions predict that dissolved phosphate could be reconstructed to 0 4 lmol kg for 1 3 1 9 lmol kg phosphate and dissolved ba to 19 nmol kg for 41 82 nmol kg basw carbonate ion concentration derived from u ca has an uncertainty of 31lmol kg for 60 120 lmol kg co 2 3

geochemistry and time series analyses of orbitally forced upper cretaceous marl limestone rhythmites lehrte west syncline northern germany a cyclic marl limestone succession of middle late campanian age has been investigated with respect to a milankovitch controlled origin of geochemical data in general the major element geochemistry of the marl limestone rhythmites can be explained by a simple two component mixing model with the end members calcium carbonate and average shale like material carbonate content varies from 55 to 90 non carbonate components are clay minerals illite smectite and biogenic silica from sponge spicules as well as authigenically formed zeolites strontian heulandite and quartz the redox potential suggests oxidizing conditions throughout the section trace element and stable isotopic data as well as sem investigations show that the carbonate mud is mostly composed of low magnesium calcitic tests of planktic coccolithophorids and calcareous dinoflagellate cysts calcispheres diagenetic overprint results in a decrease of 2 18 o and an increase in mn of up to 250 ppm however the sediment seems to preserve most of its high sr content compared to the primary low magnesium calcite of co occurring belemnite rostra the periodicity of geochemical cycles is dominated by 413 ka and weak signals between 51 and 22 5 ka attributable to orbital forcing accumulation rates within these cycles vary between 40 and 50 m ma the resulting cyclic sedimentary sequence is the product of a changes in primary production of low magnesium calcitic biogenic material in surface waters within the long eccentricity and the precession demonstrated by the caco 3 content and the mg al mn al and sr al ratios and b fluctuations in climate and continental weathering which changed the quality of supplied clay minerals the illite smectite ratio demonstrated by the k al ratio high carbonate productivity correlates with smectite favouring weathering semi arid conditions conspicuously dry and moist seasonal changes in warmer climates ti as the proxy indicator for the detrital terrigenous influx as well as rb si zr and na shows only low frequency signals indicating nearly constant rates of supply throughout the more or less pure pelagic carbonate deposition of the long lasting third order middle upper campanian sedimentary cycle

pacific pelagic phosphorus accumulation during the last 10 m y as a limiting nutrient to marine life phosphorus p is an effective tracer of today s marine productivity the distribution of p in marine sediments likewise tracks the history of marine productivity because of its relative insolubility in seawater caco3 biogenic opal terrigenous sediment and total p have been measured in cores from nine pacific sites deep sea drilling project dsdp 65 66 310 77 62 572 463 586 and gpc 3 and one subantarctic dsdp 266 site these sites were specifically chosen to provide information on biota burial flux changes with time for sedimentary sinks that represent key oceanographic variables i e rate of upwelling water depth and carbonate dissolution gradient the accumulation rates of these components for the last 10 ma were then calculated from determined core age versus depth plots core bulk density and porosity data the accumulation of p weakly correlates with that of caco3 moderately with that of total sediment and very strongly with carbonate free accumulation two prominent peaks for all components occur at 2 3 ma and 5 6 ma and record the chemical loading of dissolved caco3 sio2 and p from glacially emergent continental shelves these results indicate that continental shelf phosphorites form during interglacially high sea levels and correspond to low deep sea p accumulation rates whereas glacially lowered sea levels allow for shelf bypassing and greater deep sea p accumulation rates

links between climate and sea levels for the past three million years the oscillations between glacial and interglacial climate conditions over the past three million years have been characterized by a transfer of immense amounts of water between two of its largest reservoirs on earth the ice sheets and the oceans since the latest of these oscillations the last glacial maximum between about 30 000 and 19 000 years ago approximately 50 million cubic kilometres of ice has melted from the land based ice sheets raising global sea level by approximately 130 metres such rapid changes in sea level are part of a complex pattern of interactions between the atmosphere oceans ice sheets and solid earth all of which have different response timescales the trigger for the sea level fluctuations most probably lies with changes in insolation caused by astronomical forcing but internal feedback cycles complicate the simple model of causes and effects

gravity monitoring of tatun volcanic group activities and inference for underground fluid circulations abstract the tatun volcano group tvg located on the northern coast of taiwan adjacent to the city of taipei experiences active hydrothermalism but has no historical record of volcanic eruption yet recent studies suggest that tvg is dormant active rather than extinct to monitor mass transfers and to gain further understanding of this volcanic area gravity variations have been recorded continuously since 2012 using a superconducting gravimeter and once every few months since 2005 using absolute gravimeters we analyze the continuous gravity time series and propose a model that best explains the gravity variations due to local groundwater redistribution by correcting these variations we identify gravity changes as large as 35 gal that occurred concomitantly to fluid pressure induced earthquakes and changes in the gas composition at dayoukeng one of tvg s fumaroles over 2005 2007 we examine several fluid movements that can match the gravity observations yet too few additional constraints exist to favor any of them in particular no significant ground displacements are observed when these gravity variations occurred on the other hand the model of gravity changes due to local groundwater redistribution can be routinely computed and removed from the ongoing time gravity measurements in order to quickly identify any unusual mass transfer occurring beneath tvg

temporal variability of karst aquifer response time established by the sliding windows cross correlation method summary we study the temporal variability of water transfer through the infiltration zone of a karst aquifer by estimating the impulse response of the system using cross correlogram analyses between rainfall and piezometric level time series we apply a sliding window cross correlation method which calculates cross correlograms on partially superposed short time series windows we apply this method for rainfall and piezometric level time series at six boreholes in a fractured karstic aquifer located in burgundy france based on cross correlogram functions we obtain a time series of response time at most of the boreholes the cross correlation functions change over time and the response times vary seasonally being shorter during the summer this unusual structure can be partly explained by the seasonal variability in rainfall intensity which is higher during the summer may september inducing the seasonal behaviour of the epikarst during the summer when rainfall intensity is higher the epikarst is more easily and quickly saturated this induces an increase in lateral water transfer within the epikarst and an increase in concentrated fast flows we also show that the response time seems to tend towards a limit which represents the maximum saturation of the epikarst