modification and preservation of environmental signals in speleothems speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system however the climatological meaning of many speleothem records cannot be interpreted unequivocally this is particularly so for more subtle shifts and shorter time periods but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward

methane in underground air in gibraltar karst abstract little is known about the abundance and geochemical behaviour of gaseous methane in the unsaturated zone of karst terrains the concentrations and 13 c of methane in background atmosphere soil air and cave air collected at monthly intervals over a 4 yr period are reported for st michaels cave gibraltar where the regional climate surface and cave processes are well documented methane concentrations measured in gibraltar soil are lower than the local background atmosphere average of 1868 ppb and fall to 13 c relationships in soil air methane lack strong seasonality and suggest mixing between atmosphere and a 12 c depleted residue after methanotrophic oxidation methane abundances in cave air are also lower than the local background atmosphere average but show strong seasonality that is related to ventilation controlled annual cycles shown by co 2 cave air methane abundances are lowest in the co 2 rich air that outflows from cave entrances during the winter and show strong inverse relationship between ch 4 abundance and 13 c which is diagnostic of methanotrophy within the cave and unsaturated zone anomalies in the soil and cave air seasonal patterns characterised by transient elevated ch 4 mixing ratios with 13 c values lower than 47 suggests intermittent biogenic input dynamically ventilated gibraltar caves may act as a net sink for atmospheric methane

microstructure measurements along a quasi meridional transect in the northeastern atlantic ocean 1 this study presents vertical profiles of turbulence parameters obtained in the upper 100 m of the northeastern atlantic ocean along a transect from tropical permanently stratified waters to subpolar seasonally stratified waters in july august 2009 the focus is to fully characterize the vertical mixing along this transect for further studies related to phytoplankton and nutrient distributions derived values of temperature eddy diffusivity kt of temperature variance dissipation rate t and of turbulent kinetic energy dissipation rate e indicate a northward increase of turbulent mixing below the mixed layer in the northern stations where the wind stress is sufficiently high the vertical distributions of e in the mixed layer follow the wind stress scaling the related low wind scaling factors and the low values of e encountered at this cruise are in agreement with a strongly stratified upper water column at midday in summer

origin and distribution of carbon dioxide in the unsaturated zone of the southern high plains of texas partial pressures of co2 o2 n2 and ar were monitored at two locations in the ogallala aquifer system on the southern high plains of texas samples were collected monthly during parts of 1980 1981 from nine depths ranging from 0 6 to 36 meters below land surface pco2 was observed to be greater at depth than in the active soil zone and thus appears to contradict the normal process in which co2 is generated in the soil zone and diffuses upward to the atmosphere and downward to the water table the 13c of the co2 gas was quite uniform and averaged 17 9 per mil po2 declined with depth suggesting in situ generation of co2 by the oxidation of carbon several hypotheses were considered to explain the origin of the co2 at depth it was concluded that the most probable hypothesis was that dissolved and particulate organic carbon introduced by recharging water was oxidized to co2 by the aerobic microbial community that utilized oxygen diffusing in from the atmosphere this hypothesis is consistent with the co2 concentration profile calculated production profile of co2 13c values of co2 gas caliche soil humic acid fraction and dissolved carbonate in groundwater the abundance of co2 its concentration profile and its probable origin provide information for evaluating the observed complex sequence of caliche dissolution and precipitation known to occur in the aquifer

surface wave effects on high frequency currents over a shelf edge bank abstractseveral acoustic doppler current profilers and vertical strings of temperature conductivity and pressure sensors deployed on and around the east flower garden bank efgb were used to examine surface wave effects on high frequency flows over the bank and to quantify spatial and temporal characteristic of these high frequency flows the efgb about 5 km wide and 10 km long is located about 180 km southeast of galveston texas and consists of steep slopes on southern and eastern sides that rise from water depths over 100 m to within 20 m of the surface three dimensional flows with frequencies ranging from 0 2 to 2 cycles per hour cph were observed in the mixed layer when wind speed and stokes drift at the surface were large these motions were stronger over the bank than outside the perimeter the squared vertical velocity w2 was strongest near the surface and decayed exponentially with depth and the e folding length of w2 was 2 times larger than that of stokes drift the 2 h averaged w2 i

an approach to combined rock physics and seismic modelling of fluid substitution effects the aim of seismic reservoir monitoring is to map the spatial and temporal distributions and contact interfaces of various hydrocarbon fluids and water within a reservoir rock during the production of hydrocarbons the fluids produced are generally displaced by an injection fluid we discuss possible seismic effects which may occur when the pore volume contains two or more fluids in particular we investigate the effect of immiscible pore fluids i e when the pore fluids occupy different parts of the pore volume the modelling of seismic velocities is performed using a differential effective medium theory in which the various pore fluids are allowed to occupy the pore space in different ways the p wave velocity is seen to depend strongly on the bulk modulus of the pore fluids in the most compliant low aspect ratio pores various scenarios of the microscopic fluid distribution across a gas oil contact goc zone have been designed and the corresponding seismic properties modelled such goc transition zones generally give diffuse reflection regions instead of the typical distinct goc interface hence such transition zones generally should be modelled by finite difference or finite element techniques we have combined rock physics modelling and seismic modelling to simulate the seismic responses of some gas oil zones applying various fluid distribution models the seismic responses may vary both in the reflection time amplitude and phase characteristics our results indicate that when performing a reservoir monitoring experiment erroneous conclusions about a goc movement may be drawn if the microscopic fluid distribution effects are neglected

a global model for cave ventilation and seasonal bias in speleothem paleoclimate records cave calcite deposits speleothems provide long and continuous records of paleoenvironmental conditions in terrestrial settings typical environmental proxy measurements include speleothem growth rate and variations in elemental and isotope geochemistry commonly the assumption is made that speleothems grow continuously and at a constant rate throughout the year however seasonal variation of growth rate may be the rule in many caves here we apply observations of modern calcite growth and cave air co2 concentrations and a model of factors controlling cave ventilation to construct a global model predicting where cave calcite growth may be seasonal previous models and measurements of calcite precipitation in caves demonstrate the retardation of speleothem growth by high cave air co2 elevated co2 is commonly dissipated by ventilation driven by density differences between cave and surface air seasonal cycles in atmospheric temperature pressure and humidity commonly drive these density contrasts modeling these changes latitudinally and globally indicates a geographic control on seasonal cave ventilation and thus on a principal controlling factor of speleothem growth the model predicts that given constant water calcium and co2 inputs speleothems from temperate to boreal continental regions commonly accumulate more calcite in the cool season and less or none in the warm season these models predict that proxies from temperate to boreal speleothems may be seasonally biased due to seasonal ventilation whereas tropical and maritime records should not

turbulent large eddy momentum flux divergence during high wind events abstractmomentum transport by energy containing turbulent eddies in the oceanic mixed layer were investigated during high wind events in the northern gulf of alaska off kayak island sixteen high wind events with magnitudes ranging from 7 to 22 m s 1 were examined winds from the southeast prevailed from one to several days with significant wave heights of 5 9 m and turbulent langmuir numbers of about 0 2 0 4 surface buoyancy forcing was much weaker than the wind stress forcing the water column was well mixed to the bottom depth of about 73 m spectral analyses indicate that a major part of the turbulent momentum flux was concentrated on 10 30 min time scales the ratio of horizontal scale to mixed layer depth was from 2 to 8 turbulent shear stresses in the mixed layer were horizontally asymmetric the downwind turbulent stress at 10 20 m below the surface was approximately 40 of the averaged wind stress and was reduced to 5 10 of the wind stress near the bottom turbulent kinetic energy in the cros

carbon and oxygen isotope study of the active water carbonate system in a karstic mediterranean cave implications for paleoclimate research in semiarid regions abstract in a semiarid climatic zone such as the eastern mediterranean region annual rainfall variations and fractionation processes in the epikarst zone exert a profound influence on the isotopic compositions of waters seeping into a cave consequently the isotopic compositions of speleothems depositing from cave waters may show complex variations that need to be understood if they are to be exploited for paleoclimate studies this is confirmed by a four year study of the active carbonate water system in the soreq cave israel the 18o smow values of cave waters range from 6 3 to 3 5 the highest 18o values occur at the end of the dry season in waters dripping from stalactites and reflect evaporation processes in the epikarst zone whereas the lowest values occur in rapidly dripping fast drip waters at the peak of the rainy seasons however even fast drip waters are about 1 5 heavier than the rainfall above the cave which is taken to reflect the mixing of fresh with residual evaporated water in the epikarst zone 13c pdb values of dissolved inorganic carbon dic vary from 15 6 to 5 4 with fast drip waters having lower 13c values mostly 15 6 to 12 and higher dic concentrations relative to pool and stalactite drip water the low 13c values of fast drip waters and their supersaturation with respect to calcium carbonate indicates that the seepage waters have dissolved both soil co2 derived from overlying c3 type vegetation and marine dolomite host rock the 18o pdb values of various types of present day low magnesium calcite lmc speleothems range from 6 5 to 4 3 and 13c values from 13 to 5 5 and are not correlated with speleothem type an analysis of 18o values of present day calcite rafts and pool waters shows that they form in oxygen isotope equilibrium similarly the measured ranges of 13c and 18o values for all types of present day speleothems are consistent with equilibrium deposition at cave temperatures the 13c 18o range of contemporary lmc thus reflects the variations in temperatures and isotopic compositions of the presentday cave waters the 10 variation in the 13c values in waters can be modeled by a simple rayleigh calculation of the carbon isotope fractionation accompanying co2 degassing and carbonate precipitation these variations may obscure the differences in the carbon isotopic composition of speleothems that could arise when vegetation cover changes from c3 to c4 type plants this consideration emphasizes that it is necessary to characterize the full range of 13c values associated with contemporaneous speleothems in order to clarify the effects of degassing from those due to differing vegetation types isotopic studies of a number of different types of fossil lmc speleothems show many of them to exhibit isotopic trends that are similar to those of present day lmc but others show both higher and lower 18o ranges in particular the higher 18o range has been shown by independent age measurements to be associated with a period of drier conditions the results of the study thus indicate that it is necessary to work on a well calibrated cave system in semiarid climates and that the fossil speleothem record should be obtained from different types of contemporaneous deposit in order to fully characterize the 18o 13c range representative of any given climatic period

climate caving in to new chronologies speleothems formed in caves such as stalagmites can be dated precisely and are increasingly providing detailed and accurate records of past climates

seismic imaging of massive sulfide deposits part i rock properties laboratory measurements of the density rho and compressional wave velocity v p of massive sulfides and host rocks at elevated pressures show that ores occupy a v p rho field which is distinct from that of common silicate rocks and governed by simple mixing rules between the properties of host rocks and pure sulfide minerals the velocities of the most common sulfides are extremely variable ranging from 3 7 km s for galena through 4 7 km s for pyrrhotite 5 6 km s for sphalerite and chalcopyrite to 8 0 km s for pyrite but their densities are always high 7 6 4 6 4 1 4 2 and 5 0 g cc respectively causing ores of even intermediate grade to have high acoustic impedances this suggests that large massive sulfide bodies should make strong to spectacular seismic reflectors depending on their grade mineralogy size and setting in principle it should thus be possible to use high resolution seismic reflection techniques for base metal exploration and delineation

convectively driven mixing in the bottom boundary layer closely spaced vertical profiles through the bottom boundary layer over a sloping continental shelf during relaxation from coastal upwelling reveal structure that is consistent with convectively driven mixing parcels of fluid were observed adjacent to the bottom that were warm by several millikelvin relative to fluid immediately above on average the vertical gradient of potential temperature in the superadiabatic statically unstable bottom layer was found to be 21 7 3 1024 km 21 or 6 0 3 1025 kg m24 in potential density turbulent dissipation rates increased toward the bottom but were relatively constant over the dimensionless depth range 0 4 1 0z d where d is the mixed layer height the rayleigh number ra associated with buoyancy anomalies in the bottom mixed layer is estimated to be approximately 1011 much larger than the value of approximately 10 3 required to initiate convection in simple laboratory or numerical experiments an evaluation of the data in which the bottom boundary layer was unstably stratified indicates that the greater the buoyancy anomaly is the greater the turbulent dissipation rate in the neutral layer away from the bottom will be the vertical structures of averaged profiles of potential density potential temperature and turbulent dissipation rate versus nondimensional depth are similar to their distinctive structure in the upper ocean during convection nearby moored observations indicate that periods of static instability near the bottom follow events of northward flow and local fluid warming by lateral advection the rate of local fluid warming is consistent with several estimates of offshore buoyancy transport near the bottom it is suggested that the concentration of offshore ekman transport near the bottom of the ekman layer when the flow atop the layer is northward can provide the differential transport of buoyant bottom fluid when the density in the bottom boundary layer decreases up the slope

annual trace element variations in a holocene speleothem high resolution secondary ionization mass spectrometry sims analysis along the growth axis of a holocene speleothem from northern scotland reveals high frequency oscillations and longer term trends in mg ca sr ca and ba ca at the scale of the high frequency oscillations mg ca and sr ca display a well defined anticorrelation while sr ca and ba ca are positively correlated imaging of elemental ratios in two dimensions reveals that the high frequency signal is well preserved and laterally continuous across the sample tims 230th ages and annual ultraviolet luminescence banding provide chronological control and demonstrate that the high frequency cyclicity is annual trace element variations in speleothem calcite are a reflection of hydrochemical processes in the unsaturated zone overlying the cave supply effects and partitioning at the water calcite interface mg partitioning between water and calcite is temperature dependent calculations suggest that the annual mg ca oscillations may be caused by seasonal temperature changes however the longer timescale variations in mg ca are too great to be explained by this mechanism seasonal variations in water residence time in the unsaturated zone which reflect effective precipitation provide a more probable explanation for the observed annual oscillations and also explain the inverse relationship between mg ca and sr ca this record suggests that trace elements in speleothems have the potential to provide the high resolution insights into interannual palaeoclimatic variability required for assessment of general circulation models

elastic wave velocities chemistry and modal mineralogy of crustal rocks sampled by the outokumpu scientific drill hole evidence from lab measurements and modeling the outokumpu scientific deep drill hole intersects a 2500 m deep precambrian crustal section comprising a 1300 m thick biotite gneiss series mica schists at top followed by a 200 m thick meta ophiolite sequence underlain again by biotite gneisses mica schists 500 m thick with intercalations of amphibolite and meta pegmatoids pegmatitic granite from 2000 m downward the dominating rock types are meta pegmatoids pegmatitic granite average isotropic intrinsic p and s wave velocities and densities of rocks were calculated on the basis of the volume fraction of the constituent minerals and their single crystal properties for 29 core samples covering the depth range 198 2491 m the modal composition of the rocks is obtained from bulk rock xrf and mineral chemistry microprobe using least squares fitting laboratory seismic measurements on 13 selected samples representing the main lithologies revealed strong anisotropy of p and s wave velocities and shear wave splitting seismic anisotropy is strongly related to foliation and is in particular an important property of the biotite gneisses which dominate the upper and lower gneiss series at in situ conditions velocity anisotropy is largely caused by oriented microcracks which are not completely closed at the pressures corresponding to the relatively shallow depth drilled by the borehole in addition to crystallographic preferred orientation cpo of the phyllosilicates the contribution of cpo to bulk anisotropy is confirmed by 3d velocity calculations based on neutron diffraction texture measurements for vertical incidence of the wave train the in situ velocities derived from the lab measurements are significantly lower than the measured and calculated intrinsic velocities the experimental results give evidence that the strong reflective nature of the ophiolite derived rock assemblages is largely affected by oriented microcracks and preferred crystallographic orientation of major minerals in addition to the lithologic control c 2009 elsevier b v all rights reserved

calcite fabrics growth mechanisms and environments of formation in speleothems from the italian alps and southwestern ireland five fabrics were identified in alpine and irish caves on the basis of morphological and microstructural characteristics and re lated to growth mechanisms and growth environment columnar and fibrous fabrics grow when speleothems are continuously wet and from fluids at near equilibrium conditions low supersaturation sicc 0 35 through the screw dislocation mechanism the highly defective microcrystalline fabrics form at the same supersaturation range as co lumnar fabric but under variable discharge and the presence of growth inhibitors dendritic fabrics which have the highest density of crystal defects develop in disequilibrium conditions high supersaturation un der periodic very low flow regime periods that result in prolonged out gassing cave calcareous tufa forms in disequilibrium conditions only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near isotopic equilibrium conditions

deep seismic reflection profiling in the archaean northeastern yilgarn craton western australia implications for crustal architecture and mineral potential abstract deep seismic reflection data across the archaean eastern goldfields province northeastern yilgarn craton western australia have provided information on its crustal architecture and on several of its highly mineralised belts the seismic reflection data allow interpretation of several prominent crustal scale features including an eastward thickening of the crust subdivision of the crust into three broad layers the presence of a prominent east dip to the majority of the reflections and the interpretation of three east dipping crustal penetrating shear zones these east dipping shear zones are major structures that subdivide the region into four terranes major orogenic gold deposits in the eastern goldfields province are spatially associated with these major structures the laverton tectonic zone for example is a highly mineralised corridor that contains several world class gold deposits plus many smaller deposits other non crustal penetrating structures within the area do not appear to be as well endowed metallogenically as the laverton structure the seismic reflection data have also imaged a series of low angle shear zones within and beneath the granite greenstone terranes where the low angle shear zones intersect the major crustal penetrating structures a wedge shaped geometry is formed this geometry forms a suitable fluid focusing wedge in which upward to subhorizontal moving fluids are focused and then distributed into the nearby complexly deformed greenstones

the wangkathaa orogeny an example of episodic regional d2 in the late archaean eastern goldfields province western australia abstract the eastern goldfields province egp is a late archaean orogenic belt located on the eastern margin of the yilgarn craton the egp is characterised by a prominent nnw trending tectonic grain developed largely during regional e w oriented shortening a simplistic sequence of largely progressive compressional deformation events d 1 to d 4 has been used by previous workers to explain the development of the egp regional d 2 was thought to be responsible for most of the finite strain and therefore a reliable marker event for correlating deformation histories across the region a re examination of the deformation history has shown that d 2 kalgoorlie orogen of weinberg et al precambrian res 120 2003 219 239 was not a single progressive event rather it was episodic and involved several stages of switching of the tectonic mode compression extension switching between 2665 and 2655 ma the sequence of events during d 2 was an early stage of e w shortening d 2a followed by extension with basin formation and normal fault movement d 2e and finally a second stage of e w compression d 2b we introduce this sequence of events as the wangkathaa orogeny more complex in tectonics and broader in geographical scope than the kalgoorlie orogen features of the wangkathaa orogeny are well illustrated by the geometry and geological relationships that occur in the kurnalpi terrane welcome well area and the kalgoorlie terrane ora banda kambalda and the boorara domains of the central and southern egp available geochronology indicates that this sequence of events was likely to have been diachronous across the entire egp and the eastern southern cross province of the yilgarn craton recognition of these separate episodic stages of e w oriented compression and extension is important in our understanding the tectonic evolution of the egp switching tectonic mode between compression and extension will change the state of mean stress in a rock mass e g from net dilation to net constriction and vice versa and is an effective method in transporting and trapping mineral rich fluids the paradox of the different timings established for d 2 across the province are explained by the wangkathaa orogeny especially if it were diachronous as different workers dated different phases of an episodic orogeny

identifying mineral prospectivity using seismic and potential field data in the hongniangyu district inner mongolia china abstract since the discovery of several large porphyry mo deposits 0 1 mt mo in the jining region of inner mongolia china during the past decades the area has been receiving wide interest for mining activities however mineral exploration in this area is challenging because most of it is thickly covered by cenozoic sediments geophysical surveys especially the seismic method are becoming increasingly important for investigating deep seated ore controlling structures e g porphyry granites faults and even orebodies supporting the discovery of buried ore deposits recently potential field data and seismic reflection data have been acquired for the hongniangyu area south of jining region in this study we mainly use seismic reflection and potential field data to obtain subsurface geological model in support of mineral exploration targeting gravity and magnetic data were firstly used for spatial analysis of mineral system by mapping the distribution of the faults concealed granites and the sedimentary basin through wavelet analysis tilt angle and euler deconvolution to address the common problem of low signal to noise ratio of seismic reflection data obtained in hard rock terranes we applied a sophisticated workflow including refraction static correction noise filtering surface consistent deconvolution and velocity analysis the obtained post stack migrated seismic profile clearly imaged the geometry of the concealed graben located at the north end of the datong basin and the south east dipping kouquan normal fault controls the depression of the graben and offsets cenozoic sediments by several hectometers up to 500 m joint modeling of seismic gravity and magnetic data further provided evidence of the three buried belts of granites intriguingly one of the concealed granitic belts located in the north of hongniangyu area was found to have both significant chargeability and mo geochemical anomalies indicating a high potential of hosting porphyry type mo ore deposits as expected mo and w mineralized cores were discovered in this target area but limited to only one deep drilling hole the presented results provide the geological framework of hongniangyu district and guidelines for delineating new potential mo mineralization in the jining region

microclimatic characterization of a karstic cave human impact on microenvironmental parameters of a prehistoric rock art cave candamo cave northern spain the candamo cave contains an impor tant group of paleolithic paintings which have been seriously deteriorated due to mass tourism in this work an analysis was carried out of different cli matic parameters co2 temperature humidity 222 rn during annual cycles with the cave closed to the public and during an experimental period of controlled visits the effect of visits on the geo chemical characteristics of karstic water was also analyzed together with the cave ventilation the natural variations in the cave air co2 were above 3000 ppm the increase produced through visits was only 100 110 ppm and since the humidi ty is almost permanently at saturation point the critical parameter which limits the visitor capacity becomes air temperature the temperature changes during the annual cycle are of the order of 1 7c in the external part and less than 0 5 7c in the internal part of the cave and a maximum increase of 0 13 7c was observed during the period of the visits the 222 rn and co2 concentration minimums in the summer period july october show that this is the most propitious time for visits since the greatest ventilation is produced in the cave at this time and therefore the greatest capacity for recovery the geochemistry of the water on the other hand indi cated that this is the period of the year in which processes of wall corrosion can be most easily in troduced although this would be of limited magni tude the visitor capacity calculated was 29 visi tors day

subterranean karst environments as a global sink for atmospheric methane abstract the air in subterranean karst cavities is often depleted in methane ch4 relative to the atmosphere karst is considered a potential sink for the atmospheric greenhouse gas ch4 because its subsurface drainage networks and solution enlarged fractures facilitate atmospheric exchange karst landscapes cover about 14 of earth s continental surface but observations of ch4 concentrations in cave air are limited to localized studies in gibraltar spain indiana usa vietnam australia and by incomplete isotopic data to test if karst is acting as a global ch4 sink we measured the ch4 concentrations 13 cch4 and 2 hch4 values of cave air from 33 caves in the usa and three caves in new zealand we also measured co2 concentrations 13 cco2 and radon rn concentrations to support ch4 data interpretation by assessing cave air residence times and mixing processes among these caves 35 exhibited subatmospheric ch4 concentrations in at least one location compared to their local atmospheric backgrounds ch4 concentrations 13 cch4 and 2 hch4 values suggest that microbial methanotrophy within caves is the primary ch4 consumption mechanism only 5 locations from 3 caves showed elevated ch4 concentrations compared to the atmospheric background and could be ascribed to local ch4 sources from sewage and outgassing swamp water several associated 13 cch4 and 2 hch4 values point to carbonate reduction and acetate fermentation as biochemical pathways of limited methanogenesis in karst environments and suggest that these pathways occur in the environment over large spatial scales our data show that karst environments function as a global ch4 sink

understanding seismic reflectivity across hydrothermal alteration zones associated with gold example of the karari gold deposit western australia abstract in this study we examined whole core samples from a gold deposit in western australia the karari mine located south of the carosue dam processing plant by analyzing the mineralogy and performing petrophysical and acoustic measurements on 21 core samples representing different stages of hydrothermal alteration our goal was to document the values of acoustic impedance as a function of the degree of alteration and identify which parameters e g mineralogy porosity foliation affect the seismic reflectivity across the alteration zones to do so we measured the ultrasonic velocities and bulk density at ambient conditions for all samples as well as at confining pressures for two samples the acoustic measurements were conducted in the directions perpendicular and parallel to the foliation of the samples a subset of samples was selected to identify the mineral phases perform automated mineral mapping measure grain density and compute porosity using the bulk density grain density relation and backscattered electron bse images our results show that regardless of the direction of acquisition the acoustic impedance in the background samples is consistently smaller than that in the altered samples this difference in acoustic impedance is attributed to a porosity difference of around 2 between the background and altered samples and is not owing to the presence of alteration minerals seismic reflectivity at the background hydrothermal alteration interface decreases with increasing pressure owing to the closure of microcracks for the karari site with a targeted exploration depth between 200 m and 800 m the altered zones can be differentiated from the host rock by their acoustic impedance as the reflection coefficients are expected to vary between 0 05 and 0 13 depending on the direction of seismic propagation and depth

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

climatic and hydrological variations during the last 117 166 years in the south of the iberian peninsula from spectral and correlation analyses and continuous wavelet analyses the most complete historical series of instrumental data available spanning more than a century on rainfall temperature and outflow of a karst spring obtained from gauging stations in the south of the iberian peninsula were analysed by means of spectral and correlation analyses and continuous wavelet analyses annual periodicity of the rainfall and temperature distributions was constant over more than 100 years although weaker 6 month periodicities have also been observed as well as rainfall and temperature periodicities of 5 and 2 5 years which have also been recorded in other areas of europe these multiannual scale components can be explained by climatic variations or effects described in the literature in connection with the north atlantic oscillation nao and are likely to be the same as the climate variability at decadal to annual scale detected in several proxy data from geological records no long term trends in the distribution of precipitation and temperature were detected

carbon dioxide ground air and carbon cycling in gibraltar karst we put forward a general conceptual model of co2 behaviour in the vadose zone of karst aquifers based on physical principles of air flow through porous media and caves combined with a geochemical interpretation of cave monitoring data this gibraltar model links fluxes of water air and carbon through the soil with the porosity of the vadose zone the circulation of ground air and the ventilation of caves gibraltar hosts many natural caves whose locations span the full length and vertical range of the rock we report results of an 8 year monitoring study of carbon in soil organic matter and bedrock carbonate dissolved inorganic carbon in vadose waters and gaseous co2 in soil cave and ground air results show that the regime of cave air co2 results from the interaction of cave ventilation with a reservoir of co2 enriched ground air held within the smaller voids of the bedrock the pco2 of ground air and of vadose waters that have been in close contact with it are determined by multiple factors that include recharge patterns vegetation productivity and root respiration and conversion of organic matter to co2 within the soil the epikarst and the whole vadose zone mathematical modelling and field observations show that ground air is subject to a density driven circulation that reverses seasonally as the difference between surface and underground temperatures reverses in sign the gibraltar model suggests that cave air pco2 is not directly related to co2 generated in the soil or the epikarstic zone as is often assumed ground air co2 formed by the decay of organic matter om washed down into the deeper unsaturated zone is an important additional source of pco2 in gibraltar the addition of om derived co2 is the dominant control on the pco2 of ground air and the ca hardness of waters within the deep vadose zone the seasonal regime of co2 in cave air depends on the position of a cave in relation to the density driven ground air circulation pattern which is itself determined by the topography as well as by the high permeability conduits for air movement provided by caves themselves in the steep topography of gibraltar caves in the lower part of the rock act as outflow conduits for descending ground air in summer and so have higher pco2 in that season caves in the upper rock have high pco2 in winter when they act as outflow conduits for rising currents of co2 enriched ground air understanding seasonal flows of ground air in the vadose zone together with the origins and seasonal regimes of co2 in cave air underpins robust interpretation of speleothem based climate proxy records

cascading of water down the sloping sides of a deep lake in winter during winter the temperature of the water overlying the shallow typically 2 5 m deep shelf region around the edge of the 310 m deep lake geneva falls more rapidly than that over deeper areas this causes the spilling or cascading of relatively dense water from the shallows down the sloping sides of the lake in the form of gravity currents 2 15 m thick and typically 0 1 c cooler than the ambient the flow is intermittent with slugs of cold water lasting on average for 8 hrs with mean downslope speeds of 5 2 cms 1 the temperature and thickness of the slugs is however variable with pulses of colder water lasting for 1 3 hrs each preceded by a front in which thickness increases and temperature falls by about 0 01 c per min the net volume flux carried by the slugs is 18 5 times the mean winter flow into the lake from rivers

the hydrogeochemistry of methane evidence from english groundwaters the presence of methane ch4 in groundwater is usually only noticed when it rises to high concentrations to date rather little is known about its production or natural baseline conditions evidence from a range of non polluted groundwater environments in england including water supply aquifers aquicludes and thermal waters reveals that ch4 is almost always detectable even in aerobic conditions measurements of potable waters from cretaceous jurassic and triassic carbonate and sandstone aquifers reveal ch4 concentrations of up to 500 g l but a mean value of 10 g l however aquiclude and thermal waters from the carboniferous and triassic typically contain in excess of 1500 g l such high concentrations have so far only been found at redox eh potentials below 0 mv but in general ch4 concentration and eh value are poorly correlated this suggests a lack of thermodynamic equilibrium which is confirmed by comparing pe values calculated from the redox couple c 4 c 4 with those derived from eh genesis of ch4 appears to occur on two timescales a rapid if low rate of production from labile carbon in anaerobic microsites in the soil and a much longer millennium scale of production from more refractory carbon methane is rarely measured in groundwater there is no single ionic determinand which acts universally as a proxy but a combination of high hco3 and low so4 concentrations or the reverse is an indication that high amounts of ch4 may be present

multiple origins of methane in the earth methane occurrences in the earth s crust are predominantly of biogenic origin i e their ultimate source is biologically formed organic matter methane can also form through inorganic reactions and is consequently termed abiogenic biogenic methanes can either form through bacterial or thermogenic processes bacterial processes follow a co2 reduction and or fermentation pathway the fermentation processes are quantitatively more important in recent fresh sediments and swamps methane formed by co2 reduction however is most common in older sediments and commercial gasfields temperature organic substrate and age may be the major factors controlling the relative importance of the two pathways stable isotope concentrations in thermogenic methanes seem to be controlled by the extent of conversion of organic matter the timing of gas expulsion and trapping the different character of methane in individual sedimentary basins may be a result of the geologic history geothermal methanes are most likely derived from pyrolysis of organic matter abiogenic methane occurs in hydrothermal vents and ophiolite complexes inorganic reactions either surficial or deep seated are the likely source of such methanes a uniform mantle origin of methane is not supported by the observed isotope variations in naturally occurring methanes

archean gold mineralization in an intrusion related geochemically zoned district scale alteration system in the carosue basin western australia the carosue basin in the eastern goldfields of the archean yilgarn craton western australia is a late stage syntectonic sequence of feldspathic volcaniclastic sedimentary rocks that unconformably overlies deformed greenstones it was intruded by a suite of monzonitic syenitic and lamprophyric magmas that form numerous plugs and dikes within the carosue basin the intrusions are most voluminous at carosue dam where the basin and underlying greenstones are cut by a swarm of north south trending faults a large hydrothermal alteration system several kilometers wide and at least 10 km long is centered on this area zones of sodic albite and potassic biotite alteration are enveloped sequentially by phyllic muscovite and propylitic chlorite alteration a central zone of anomalous bi w mo cu pb ag enrichment is enveloped by a zone of relative zn and as enrichment more or less coincident with the muscovite alteration zone the district scale potassic alteration is attributed to magmatic fluids derived from the intermediate to felsic intrusions the origin of the sodic alteration is uncertain but could be attributed to a magmatic fluid or a mesothermal orogenic fluid two styles of gold mineralization are present within the carosue dam area both types are associated with north south faults the most common type karari type mineralization is best developed in the sodic and potassic alteration zones and is further associated with subvolcanic intrusions disseminated hematite in sodic alteration zones and disseminated pyrite there is a poor correlation between gold grades and quartz carbonate veins the second style of mineralization represented by the twin peaks deposit occurs in a sequence of more mature siliciclastic metasedimentary rocks that lie just outside the carosue basin within the district scale muscovite alteration zone intrusions and hematite are volumetrically minor or absent at twin peaks gold occurs in quartz carbonate veins and is associated with intense carbonate alteration and arsenopyrite the carosue dam district represents an important example of a large archean intrusion related hydrothermal system with contrasting styles of associated gold mineralization the origin of karari and other deposits of this class is equivocal and could be related to magmatic fluids or reaction of a mesothermal orogenic fluid with feldspar rich host rocks twin peaks is an example of an orogenic gold deposit that has been superimposed on the distal parts of the intrusion related alteration system

calcite moonmilk crystal morphology and environment of formation in caves in the italian alps abstract calcite moonmilk which is a cave deposit formed of calcite crystals and water is found in many caves in the italian alps these modern and ancient deposits are formed of fiber calcite crystals 50 500 nm wide and 1 to 10 m long and polycrystalline chains that have few crystal defects radiocarbon dating indicates that most moonmilk deposits in these caves are fossil and that for most precipitation ceased 6400 cal years bp at the end of the mid holocene hypsithermal in the caves of the italian alps the optimal conditions for formation of calcite moonmilk are 1 a temperature range of 3 5 5 5 c 2 low discharge volumes of seepage waters that are slightly supersaturated sical 0 0 to 0 2 and 3 relative humidity that is at or close to 100 microbial activity apparently did not play an active role in the formation of the calcite moonmilk conditions for moonmilk formation are typically found in caves that are located beneath land surfaces which are soil covered and support a conifer forest precipitation of the fiber calcite crystals apparently involved very slow flow of slightly supersaturated fluids the fact that moonmilk appears to form under a narrow range of environmental conditions means that this cave deposit has potential as a paleoclimatic indicator in high alpine karst areas

soil and karst aquifer hydrological controls on the geochemical evolution of speleothem forming drip waters crag cave southwest ireland abstract in recent years there has been increased interest in cave speleothems as archives of palaeoclimate monitoring of rainfall and soil and karst water chemistries was performed at crag cave castleisland co kerry southwest ireland in august 1997 and january 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution piston flow source change and prior calcite precipitation during aquifer throughflow evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries as a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site we propose that a palaeohydrological signal may be recorded by crag cave speleothems that may be interpreted via the study of mg ca ratios in speleothems linked to monitoring of modern drip water chemistry

seismic properties of the voisey s bay massive sulfide deposit insights into approaches to seismic imaging abstractseismic methods offer significant potential advantages for minerals exploration over more traditional geophysical techniques because of the comparatively high resolution of seismic imaging this is particularly true as minerals exploration is required to explore deeper to find resources however adaptation of seismic imaging techniques to the complex crystalline targets common in the mining environment requires a thorough understanding of the physical properties of the specific combination of ore and host rocks under consideration to choose an appropriate imaging technique analysis of the sulfide ores and associated host rocks from the voisey s bay nickel copper cobalt deposit indicates that in the pyrrohotite pentlandite rich but pyrite poor assemblage at voisey s bay seismic velocities are significantly lower mean 4500 m s than either the felsic or mafic host rocks mean 5900 m s and 6400 m s this observation is in contrast with pyrite rich massive sulfide ores that have velocities th

bubble clouds and the dynamics of the upper ocean this is a review of turbulence in the upper ocean close to the sea surface particularly of the information that has been obtained from sonar observations of bubble clouds produced by breaking wind waves these clouds provide tracers of the turbulent motions and are important especially at high wind speeds in the process of air sea gas transfer the observations of bubble clouds are here related to other measurements of turbulence particularly to direct measurements of currents and temperatures in lakes or at sea and to laboratory studies some novel observations of bubble clouds and breaking waves their frequency and relation to langmuir circulation are presented there is now emerging a pattern of clues that point to the dominance of breaking surface gravity waves as a source of turbulence to a depth below the surface of 0 04 to 0 2 times the wavelength of the dominant breaking waves although the effect of swell has yet to be clarified the relative depth appears to increase with increasing values of w 1 c where w10 is the wind speed and c the phase speed of the dominant waves below this region the generation of turbulence may be dominated by shear stress or convection here turbulence is generally similar to that in the atmospheric boundary layer there are however coherent motions on the scale of the mixing layer that persist for periods of a few minutes to an hour or so to which the transport of a large part of the momentum and heat fluxes can be attributed and which strongly affect the dispersion of buoyant particles or bubbles these motions deserve special study to establish their contribution to heat and momentum transport and hence to determine if or when they should be specifically represented in models of the upper ocean devised for example to describe the dispersion of passive and non passive tracers or the air sea transfer of gases

observations of mixing near the sides of a deep lake in winter the dissipation rate of turbulent kinetic energy per unit mass vertical eddy diffusivity kz and the rate of dissipation of temperature variance x are estimated over the sloping sides of lake geneva both far from and near the bed using temperature data from horizontal tracks of a submarine during periods of winter cooling the estimated values are about one order of magnitude greater near the slope than those distant from it the mean dissipation rate per unit mass averaged over the epilimnion varies between o 10 210 m 2 s 23 in calm weather to o 10 28 m 2 s 23 in winds of 8 m s 21 for surface buoyancy fluxes of 6 3 10

trace element variation in speleothem aragonite potential for palaeoenvironmental reconstruction trace element variation in annually laminated stalagmites has the potential to record long term high resolution palaeoclimatic data provided both 1 the relationship between trace element content in the carbonate and the climate and 2 the mechanism of stalagmite growth are understood here we report a secondary ion mass spectrometry sims study of an aragonitic speleothem t7 from cold air cave southern africa which achieves small m spatial resolution and ppm precision t7 has a series of fine visible laminae believed to be annual to subannual this article establishes 1 the usefulness of sims in analyzing speleothem aragonite at the spatial resolution and precision relevant to climatic studies 2 the distribution of trace elements in aragonite on micron scales and their relationship to models for speleothem growth and 3 the potential of aragonite speleothems to encode climatic data at subannual resolution complex reproducible oscillations in sr ca and ba ca are observed parallel to the growth direction of the speleothem however in addition to this variability we observe trace element oscillations perpendicular to the growth direction and infer that aragonite crystallites in the speleothem are laterally as well as vertically zoned stepscans parallel to the growth direction demonstrate complex zoning patterns from which simple climatic data are difficult to extract due to small scale lateral heterogeneity in the aragonite however time series analysis of the whole data set reveals regular cycles in sr ca and ba ca at a scale that matches the magnitude of the visible laminae on this basis it appears that within the complex geochemical variability there resides a regular environmental control possibly variation in water throughput hence rainfall

a 53 year seasonally resolved oxygen and carbon isotope record from a modern gibraltar speleothem reconstructed drip water and relationship to local precipitation abstract the response of a climate proxy against measured temperature rainfall and atmospheric circulation patterns at sub annual resolution is the ultimate test of proxy fidelity but very few data exist showing the level of correspondence between speleothem climate proxies and the instrumental climate record cave sites on the gibraltar peninsula provide a unique opportunity to calibrate speleothem climate proxies with the longest known available precipitation isotopes and instrumental records an actively growing speleothem sampled from new st michaels cave in 2004 is composed of paired laminae consisting of light columnar calcite and a darker microsparitic calcite stable isotope analysis of samples micromilled in 100 m steps at the equivalent of bi monthly intervals reveals fabric correlated annual cycles in carbon isotopes oxygen isotopes and trace elements responding to seasonal changes in cave microclimate hydrology and ventilation patterns calcite 13 c values reach a minimum in the light columnar fabric and evidence from trace element behaviour and cave monitoring indicates that this grows under cave winter conditions of highest p co 2 whereas the dark microsparitic calcite characterised by elevated 13 c and 18 o values grows under low summer p co 2 conditions drip water 13 c dic reaches a minimum in march april at which time the attenuated 18 o signal becomes most representative of winter precipitation an age model based on cycle counting and the position of the 14 c bomb carbon spike yields a precisely dated winter oxygen isotope proxy of cave seepage water for comparison with the gnip and instrumental climate record for gibraltar the 18 o characteristics of calcite deposited from drip water representing winter precipitation for each year can be derived from the seasonally resolved record and allows reconstruction of the 18 o drip water representing winter precipitation for each year from 1951 2004 these data show an encouraging level of correspondence r 2 0 47 with the 18 o of rainfall falling each year between october and march and on a decadal scale the 18 o of reconstructed winter drip water mirrors secular change in mean winter temperatures

dynamical processes of transfer at the sea surface abstract this review describes the dynamical processes of transport from and immediately below the sea surface particularly those which involve convergence and the separation of flow and which result in the renewal of surface water at horizontal scales ranging from millimeters to hundreds of meters turbulence at or near the sea surface derives from several processes breaking waves and the bubbles they may produce precipitation and spray langmuir circulation and thermal convection and turbulence which is internally generated by shear interest in the subject derives from the requirements to predict air sea fluxes of heat momentum and gases to develop climate models to interpret satellite images of the sea surface including those of ship wakes and to predict upper ocean structure including mixing layer depth in models of phytoplankton blooms and acoustic propagation the general effect of subsurface turbulence on the sea surface and the effects of surfactants is described and each process is discussed in turn laboratory experiments and theoretical studies have contributed particularly to the understanding of the interaction of vortices and turbulence with the surface and to the consequences of breaking waves they point to the development of instability in the flow ahead of steep waves carrying parasitic capillary waves which may contribute to the onset of flow separation on the leading face of the waves and the development of a rotor or roller below the wave crest shown most clearly in the pattern of streamlines in a frame of reference moving forward with the wave the conditions near the flow separation line on the wave surface ahead of the rotor may be similar to those produced by vortices approaching a free surface detailed observation of breaking waves at sea is lacking but some progress has been made using acoustics to detect the clouds of subsurface bubbles formed by the larger breakers and the depth to which they penetrate the possible importance of three dimensional effects in breaking waves is discussed and a conjectural sketch of the surface flow field and the surface separation and reattachment pattern following a plunging breaker is described recent observations show elevated levels of turbulence close to the sea surface the depth of the layer in which this occurs is shown to be consistent with information derived from sonar studies of the depth of bubble clouds the observed frequency of breaking waves and laboratory observations of breaking waves rain is known to knock down the sea reducing the frequency and intensity of breaking waves the precise mechanics of the phenomena are uncertain but an enhancement of near surface turbulence and the damping of short surface gravity waves has been observed in laboratory experiments langmuir circulation temperature ramps and convection all associated with coherent structures are processes which mix the upper ocean although their relative importance is unknown connections between studies with quite disparate motivations are found to help provide descriptions of the upper ocean processes and estimates of the time scale of surface renewal associated with each of the processes identified many quantities being transferred across the sea surface appear to be transported by dynamical processes of scale much smaller than that of the dominant surface waves although their subsequent diffusion in the mixing layer may be strongly influenced by the larger scale processes further careful measurements in the laboratory and at sea are required to quantify the fluxes associated with the processes and to relate them to external parameters such as wind speed

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

neotectonics and shoreline history of the rock of gibraltar southern iberia abstract several sets of staircased quaternary marine deposits can be observed along the gibraltar coast ranging from 1 to 210 m above the present mean sea level geomorphological mapping establishes from the relationship between shore scree and dune sedimentary formations five main morphotectonic steps on the rock marine terraces between 1 and 25 m 30 60 m 80 130 m 180 210 m and above each terrace level and its slope aeolian linked sediments is backed by a steep relict sea cliff margin so forming a composite cliff the most recent coastal landforms and sediments are associated with the last 250 ka linked to oxygen isotope stages ois 1 3 5 and 7 these landforms determine a morphosedimentary highstand lowstand sequence with several staircased and offlapped episodes comprising a major morphotectonic step a well developed palaeocliff usually separates the highstand marine terraces of ois 9 from those of ois 7 the gibraltar mean tectonic uplift value of 0 05 0 01 mm yr is maintained from 200 ka to the present before this at least to 250 ka the mean uplift rate was higher 0 33 0 05 mm yr possibly compatible with major tectonic events in response to a nnw sse compressive stress field between africa and iberia

influence of rainfall quantity on the isotopic composition 18o and 2h of water in mountainous areas application for groundwater research in the yunquera nieves karst aquifers s spain abstract the isotopic composition 18 o and 2 h of rainwater and groundwater was determined in the yunquera nieves hydrogeological unit a karstic massif in s spain with complex orography and hydrogeology the aims were to identify 1 the source of the water 2 the main factors determining the isotopic content 3 the catchment area of the springs and 4 the aquifer behaviour the isotopic content of the sampled waters is of mixed atlantic mediterranean origin and is opposite to the quantity of rainwater distribution both in space and time spatially water is isotopically less depleted toward the eastern sector where rainwater quantity is lower which is locally affected by the orography thus it is possible to differentiate the catchment areas of the main springs aquifer recharge is produced by winter precipitation when rainfall water is isotopically more negative and evaporation is lower the decrease in rainfall quantity during the study period provoked an increase in 18 o and 2 h values both in rainwater and in groundwater the recorded variations of the isotopic content of the rainfall are rapidly evident in the spring waters which demonstrates a well developed karst network inside the carbonate aquifers and thus the existence of conduit flow systems

consumption of atmospheric methane in a limestone cave in indiana usa abstract recent observations suggest that karst landscapes may be an unaccounted sink for atmospheric ch4 but questions remain about the processes contributing to sub atmospheric ch4 mole fractions in caves the ch4 dynamics associated with karst environments were studied over 18 months at 6 locations in buckner cave southern indiana by measuring the mole fractions and stable isotopic composition of ch4 and carbon dioxide co2 co2 mole fractions were used to infer seasonal changes in airflow samples were obtained on a monthly basis ch4 mole fractions ranged from 1 9 0 1 ppm near the cave entrance to 0 1 0 1 ppm in the more remote parts of the cave the carbon and hydrogen stable isotopic compositions of ch4 in the cave ranged from 58 7 to 7 vpdb and 170 to 10 vsmow respectively the isotopic data suggest that the ch4 dynamics of buckner cave can be described by a seasonally variable mixing system in which atmospheric ch4 enters primarily through the main entrance and is subsequently consumed by methanotrophs additionally at least two smaller ch4 sources are evident when air has been stagnant the results suggest that subterranean karst cavities are an important sink for atmospheric ch4

similarity structure in the convective boundary layer of a lake natural convection influences a variety of geophysical phenomena including daily mixing cycles in the atmosphere and in surface waters the seasonal overturn of lakes and global climate variability conceptual models of convection in water are primitive and based on very limited data particularly at small dissipative scales here i present an analysis of microscale data from the convective boundary layer of a lake indicating a complex depth dependence in the rate at which temperature fluctuations are dissipated suitably scaled this vertical structure is remarkably similar to that found in the atmospheric convective boundary layer1 2 stirred by rising thermals of buoyant air heated at the earth s surface this comparison consistent with recent documentation of similarity in the more uniform vertical structure of energy dissipation3 5 suggests another unifying link in the structure and dynamics of convection in boundary layers of lakes oceans and the atmosphere6

seismic methods in mineral exploration and mine planning a general overview of past and present case histories and a look into the future abstractdue to high metal prices and increased difficulties in finding shallower deposits the exploration for and exploitation of mineral resources is expected to move to greater depths consequently seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration these methods also can be used with varying degrees of success to directly target mineral deposits at depth we review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions australia europe canada and south africa a wide range of case studies are covered including some that are published in the special issue accompanying this article from surface to borehole seismic methods as well as petrophysical data and seismic modeling of mineral deposits at present high resolution 2d surveys mostly are performed in mining areas but there is a general increasing trend in the use of 3

seasonal variations in modern speleothem calcite growth in central texas u s a variations in growth rates of speleothem calcite have been hypothesized to reflect changes in a range of paleoenvironmental variables including atmospheric temperature and precipitation drip water composition and the rate of soil co2 delivery to the subsurface to test these hypotheses we quantified growth rates of modern speleothem calcite on artificial substrates and monitored concurrent environmental conditions in three caves across the edwards plateau in central texas within each of two caves different drip sites exhibit similar annual cycles in calcite growth rates even though there are large differences between the mean growth rates at the sites the growth rate cycles inversely correlate to seasonal changes in regional air temperature outside the caves with near zero growth rates during the warmest summer months and peak growth rates in fall through spring drip sites from caves 130 km apart exhibit similar temporal patterns in calcite growth rate indicating a controlling mechanism on at least this distance the seasonal variations in calcite growth rate can be accounted for by a primary control by regional temperature effects on ventilation of cave air co2 concentrations and or drip water co2 contents in contrast site to site differences in the magnitude of calcite growth rates within an individual cave appear to be controlled principally by differences in drip rate a secondary control by drip rate on the growth rate temporal variations is suggested by interannual variations no calcite growth was observed in the third cave which has relatively high values of and small seasonal changes in cave air co2 these results indicate that growth rate variations in ancient speleothems may serve as a paleoenvironmental proxy with seasonal resolution by applying this approach of monitoring the modern system speleothem growth rate and geochemical proxies for paleoenvironmental change may be evaluated and calibrated

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

stable isotope microsampling of speleothems for palaeoenvironmental studies a comparison of microdrill micromill and laser ablation techniques three different techniques are currently in use to microsample speleothem and tufa specimens at moderate to high spatial resolution manual microdrilling using a dentist drill semi automated micromilling and laser ablation while a separate handling step is involved in the first two techniques transferring the sample powder to an on line carbonate preparation system linked to an isotope ratio mass spectrometer the laser is directly interfaced with the mass spectrometer via a gas preparation device in this study we compare stable c and o isotope results obtained by these three preparation techniques using continuous he flow mass spectrometry on the same speleothem samples the overall consistency of the results is satisfactorily high in particular between the micromill and the laser data although the precision of the laser data is slightly lower than analyses obtained by the other two methods in particular with respect to 18o the speed of acquisition renders laser ablation a useful reconnaissance technique for rapidly analyzing long sections of speleothems micromilling is the method of choice to obtain highly spatially resolved isotope data of high analytical precision while microdrilling is still an low cost alternative for sampling at comparably low resolution e g of fast growing stalagmites

petrophysics and mineral exploration a workflow for data analysis and a new interpretation framework abstract as mineral exploration seeks deeper targets there will be a greater reliance on geophysical data and a better understanding of the geological meaning of the responses will be required and this must be achieved with less geological control from drilling also exploring based on the mineral system concept requires particular understanding of geophysical responses associated with altered rocks where petrophysical datasets of adequate sample size and measurement quality are available physical properties show complex variations reflecting the combined effects of various geological processes large datasets analysed as populations are required to understand the variations we recommend the display of petrophysical data as frequency histograms because the nature of the data distribution is easily seen with this form of display a petrophysical dataset commonly contains a combination of overlapping sub populations influenced by different geological factors to understand the geological controls on physical properties in hard rock environments it is necessary to analyse the petrophysical data not only in terms of the properties of different rock types it is also necessary to consider the effects of processes such as alteration weathering metamorphism and strain and variables such as porosity and stratigraphy to address this complexity requires that much more supporting geological information be acquired than in current practice the widespread availability of field portable instruments means quantitative geochemical and mineralogical data can now be readily acquired making it unnecessary to rely primarily on categorical rock classification schemes the petrophysical data can be combined with geochemical petrological and mineralogical data to derive explanations for observed physical property variations based not only on rigorous rock classification methods but also in combination with quantitative estimates of alteration and weathering to understand how geological processes will affect different physical properties it is useful to define three end member forms of behaviour bulk behaviour depends on the physical properties of the dominant mineral components density and to a lesser extent seismic velocity show such behaviour grain and texture behaviour occur when minor components of the rock are the dominate controls on its physical properties grain size and shape control grain properties and for texture properties the relative positions of these grains are also important magnetic and electrical properties behave in this fashion thinking in terms of how geological processes change the key characteristics of the major and minor mineralogical components allows the resulting changes in physical properties to be understood and anticipated

subterranean microbial oxidation of atmospheric methane in cavernous tropical karst abstract subterranean methanotrophy is a potentially important but overlooked sink for the atmospheric greenhouse gas methane ch 4 this study documents a microbial ch 4 sink in tropical subterranean karst cavities in vietnam s northern karst province where porosity steep topography and scarce soil and vegetation cover foster the exchange of subterranean air with the atmosphere our data are based on i surveys of ch 4 carbon dioxide and radon concentrations in the air of 11 caves ii in situ mesocosm experiments in caves as well as iii laboratory mesocosm measurements using sediment and rock from caves the extent of ch 4 depletion in cave air depends on the ventilation rate and the availability of moisture to provide a habitat for ch 4 oxidizing bacteria both of which are seasonally variable in northern vietnam and in part depend on monsoonal activity mesocosm experiments using fresh versus sterilized rock and sediment confirmed the role of microbial methanotrophy towards uptake of ch 4 from cave air our results also suggest that within cave heterogeneity of environmental variables like salinity may affect rates of ch 4 oxidation we conservatively estimate that 150 000 metric tons of atmospheric ch 4 are microbially oxidized annually in the 29 000 km 2 of vietnamese tropical karst which would compensate for 7 of vietnam s agricultural ch 4 emissions from rice farming and livestock future studies estimating the global fluxes of the atmospheric greenhouse gas ch 4 should consider subterranean karst as a potentially important ch 4 sink

annually laminated sequences in the internal structure of some belgian stalagmites importance for paleoclimatology abstract fifteen stalagmites from four caves and one sealed tunnel in southern belgium are composed of alternations of annually deposited white porous and dark compact laminae this is demonstrated by comparing the number of laminae with the local history of the site for modern stalagmites and with radioisotopic ages for late glacial and holocene stalagmites annual cyclicity in the internal structure of these speleothems is explained by the highly seasonal variations of the water excess which influences underground water flow comparison between climatic data and modern stalagmites of a closed tunnel shows that growth laminae can record climatic variations 1 there is a good correlation r 0 84 between lamina thickness in a stalagmite and water excess 2 during years with a high water excess dark compact laminae are more developed which makes the speleothem darker vertical successions of several laminae represent microsequences that may have recorded climatic variations with a time resolution of 1 2 year in a late glacial stalagmite successive laminae microsequences form very regular cycles of 11 years separated by a thick darkcompact lamina it is supposed that as for modern stalagmites the thick dark compact lamina corresponds to a period of high water excess hence this 11 year cycle may reflect a climatic cycle

spatial variability of cave air carbon dioxide and methane concentrations and isotopic compositions in a semi arid karst environment there is insufficient information on the movement of air in karst environments to constrain the uncertainty associated with quantifying sources and sinks of methane ch4 and carbon dioxide co2 within caves for global carbon accounting we analysed cave air samples for their co2 and ch4 concentrations co2 and ch4 and carbon isotopic compositions from sampling campaigns in winter august 2014 and summer february 2015 at numerous heights and locations throughout gaden and cathedral caves in a semi arid environment wellington caves nsw australia ventilation is the dominant control on cave air co2 and ch4 with the highest cave air co2 concentrations co2 cave occurring in summer in association with the lowest cave air ch4 concentrations ch4 cave analyses show that the cave air co2 has both atmospheric and soil sources soil air and cave air in both caves undergo methanogenesis and methanotrophy but we identify cave specific differences in cave air ch4 and co2 ch4 cave in cathedral cave shows an inverse relationship to co2 cave particularly in areas separated from the main cave passage in contrast gaden cave has near atmospheric ch4 cave and isotopic ratios present at all locations sampled in winter where no ventilation is occurring in summer ch4 cave in gaden cave decreases but remains reasonably high compared to cathedral cave our research shows adjacent caves vary in their ability to act as a net sink for ch4 and highlights the need for further studies before global generalisations can be made about the carbon budget of karst environments

cave air control on dripwater geochemistry obir caves austria implications for speleothem deposition in dynamically ventilated caves there are very few process studies that demonstrate the annual variation in cave environments depositing speleothems accordingly we initiated a monitoring program at the obir caves an austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pco2 during summer and low pco2 in winter although similar seasonal changes in soil pco2 occur they are not directly connected with the changes in the subsurface since the dripwaters are fed from a well mixed source showing little seasonal variation cold season flushing by relatively co2 poor air enhances degassing of co2 in the cave and leads to a high degree of supersaturation of dripwater with regard to calcite forced calcite deposition during the cold season also gives rise to a pronounced pattern of synchronous seasonal variations in electrical conductivity alkalinity ph ca and 13cdic which parallel variations recorded in 13ccave air chemical components unaffected by calcite precipitation e g d 18o sio2 so4 lack a seasonal signal attesting to a long residence in the karst aquifer modeling shows that degassing of co2 from seepage waters results in kinetically enhanced c isotopic fractionation which contrasts with the equilibrium degassing shown from the soreq cave in israel the obir caves may serve as a case example of a dripstone cave whose seepage waters and speleothems show intra annual geochemical variability that is primarily due to chemical modification of the groundwater by a dynamic bidirectional subsurface air circulation

coherent structures at the ocean surface in convectively unstable conditions the turbulent boundary layer at the ocean surface has some dynamical similarities to the atmospheric boundary layer1 4 the atmospheric turbulent boundary layer may exhibit not only random fluctuations but also spatially coherent organized motion5 6 thorpe1 conjectured that such organized motion should also be found in the upper ocean boundary layer in convectively unstable conditions here i report on observations made in the tropical atlantic ocean which confirm this view horizontal temperature profiles obtained at a depth of 2 m at night revealed ramp like structures vertical velocity profiles in the upper few metres of the ocean was determined using a free rising profiler and exhibited abrupt changes corresponding to sudden changes in temperature these features are known5 6 to be characteristic of spatially coherent organized motions in turbulent boundary layers

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

annual trace element cycles in calcite aragonite speleothems evidence of drought in the western mediterranean 1200 1100 yr bp each of two calcitic stalagmites from grotte de clamouse herault southern france displays a discrete aragonite layer dated at around 1100 yr bp the layer of fanning aragonite ray crystals is immediately preceded by calcite with mg and sr compositions that are uniquely high for the past 3 kyr trace element compositions close to the boundary between original aragonite and calcite are consistent with quasi equilibrium partitioning of trace elements between the phases study of modern dripwaters demonstrates that pronounced covariation of mg ca and sr ca ratios in dripwater occurs owing to large amounts of calcite precipitation upflow of the drips that fed the stalagmites trace element to ca ratios are enhanced during seasonally dry periods ion microprobe data demonstrate a pronounced covariation of trace elements including mg and sr in calcite and sr u and ba in aragonite the mean peak spacing is close to the long term mean of annual growth rates determined by differences in u series ages and so the trace element peaks are interpreted as annual the trace element chemistry of the stalagmites on annual to inter annual scales thus directly reflects the amounts of prior calcite precipitation interpreted as an index of aridity the longer term context is a multi decadal period of aridity 1200 1100 yr bp possibly correlated with an analogous episode in central america the arid period culminated in the nucleation of aragonite but within a decade was followed by a return to precursor conditions copyright 2005 john wiley sons ltd

observations of a quasi shear free lacustrine convective boundary layer stratification and its implications on turbulence 1 convection due to surface cooling has been investigated in the surface boundary layer of a small lake under near ideal conditions undisturbed by wind large scale currents and differential cooling successive temperature microstructure profiles revealed a stable stratification in the lower bulk of the convective boundary layer despite strong cooling over the entire layer lateral heat fluxes as well as heat exchange with the thermocline could be excluded as driving mechanism of the observed stratification acoustic doppler current profiler adcp measurements indicated an asymmetric pattern of vertical velocities strong downward plumes were observed upon a background of slow upflow we suggest that this asymmetry allows cold water from the super adiabatic surface layer to intrude at the base of the convective layer thus causing the observed stratification this in particular involves downward plumes that feature a relatively low entrainment rate in the center bulk of the convective layer corresponding large eddy simulation studies as well as thermistor string and adcp data were found consistent with this scenario the dissipation rate of turbulent kinetic energy tke was estimated on the basis of the temperature microstructure profiles and from the adcp data mean dissipation rates of only about 20 of the surface buoyancy flux were typically identified this finding is attributed to respectively low buoyant production rates of tke attenuated by strong convective plumes penetrating through the stable stratification in the lower bulk of the convective layer into the thermocline index terms 4568 oceanography physical turbulence diffusion and mixing processes 4524 oceanography physical fine structure and microstructure 4572 oceanography physical upper ocean processes 4239 oceanography general limnology keywords convection temperature microstructure adcp stratification turbulent kinetic energy convective boundary layer

in situ measurement of seasonal δ18o variations and analysis of isotopic trends in a modern speleothem from southwest australia we present a record of seasonal and inter annual oxygen o and carbon c isotope ratios from an 81 year old stalagmite from moondyne cave southwest australia the growth history of stalagmite mnd s1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992 this stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal wet winter dry summer and has experienced a 200 mm 20 reduction of mean rainfall since the mid 1960s and a 0 8 c temperature rise since 1953 seasonal variations in calcite o were measured in situ by high spatial resolution ion microprobe whilst inter annual variations of o and c were measured by conventional gas source mass spectrometry comparison of the speleothem stable isotopes and instrumental temperature records reveals that o variations are too large to be driven by temperature alone and are in the opposite sense however daily rainfall o measurements show that the mean seasonal range in o of rainfall in southwest australia is large 2 and inversely correlated with rainfall amount a rainfall driver for the speleothem o is confirmed by the detection of seasonal shifts of 0 7 1 5 in speleothem that track rainfall o smoothed by storage in the overlying limestone the seasonal range in speleothem o is larger than any inter annual and decadal variation observed in the record the prominent annual cycles in speleothem o revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events or possibly also moisture sources could produce significant changes in mean speleothem o the ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters if this is the case then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean o and c that have a complex relation to climate this finding should be generally applicable to the interpretation of long term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large including most of the sub tropical monsoon belts and mid to high latitudes with distinct rainfall seasons

stable isotope study of cave percolation waters in subtropical brazil implications for paleoclimate inferences from speleothems we analyze the interannual monthly variability of oxygen isotope ratios in data from iaea stations along the atlantic coast of south america between 238 and 348 s to evaluate the influence of parameters such as temperature rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical brazil in addition a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the santana cave system 24831v s 48843v w is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water d 18 o interannual monthly variations in d 18 o of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer negative values of d 18 o to a more extratropical regime in winter positive values of d 18 o variations in groundwater d 18 o indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters regardless of location of collection in the cave in addition the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs significant perturbations in the groundwater composition characterized by more positive values of d 18 o are probably connected to an increased atlantic moisture contribution associated with extratropical precipitation this implies that the d 18 o of speleothems from caves in this region may be a suitable proxy for studying