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

gypsum caves as indicators of climate driven river incision and aggradation in a rapidly uplifting region detailed geomorphological analysis has revealed that subhorizontal gypsum caves in the northern apennines italy cut across bedding planes these cave levels formed during cold periods with stable river beds and are coeval with fluvial terraces of rivers that flow perpendicular to the strike of bedding in gypsum monoclines when rivers entrench renewed cave formation occurs very rapidly resulting in the formation of a lower level river aggradation causes cave alluviation and upward dissolution paragenesis in passages nearest to the river beds the u th dating of calcite speleothems provides a minimum age for the formation of the cave passage in which they grew which in turn provides age control on cave levels the ages of all speleothems coincide with warmer and wetter periods when co 2 availability in the soils covering these gypsum areas was greater this climate driven speleogenetic model of epigenic gypsum caves in moderately to rapidly uplifting areas in temperate regions might be generally applicable to karst systems in different geological and climatic conditions

a reduced order successive linear estimator for geostatistical inversion and its application in hydraulic tomography national natural science foundation of china 51779179 51609173 51479144 51522904 crdf daa2 15 61224 1 tianjin normal university from the thousand talents plan of tianjin city special fund for public industry research from ministry of land and resources of china 201511047

airborne synthetic aperture radar tracking of internal waves in the strait of gibraltar abstract as part of the international gibraltar experiment we realized on june 22 and 24 1986 two surveys of the strait of gibraltar on board an aircraft equipped with a synthetic aperture radar our objective was to observe at spring tides and during two twelve hour tidal cycles at 24 h interval the generation of internal wave trains linked to the hydraulic jump formed west of the sill during the westward phase of the tidal current and their eastward propagation in the strait the speed of propagation of these waves and the effect of the diurnal component of the tide on their generation and propagation could then be determined our results suggest that two solitary waves of equal amplitude propagated eastwards in the strait on june 22 the tidal coefficient being equal to 92 with a speed relative to the ground of 2 1 to 2 6 m s 1 24 h later during the second survey on june 24 tidal coefficient 90 we observed the propagation of a train of non linear waves the speed of the leading wave of which being about 1 9 ms 1 our data show that other waves pass over the camarinal sill after the release of the bore and secondary internal wave trains are shown to propagate eastwards from there although our sar data show the appearance of waves west of the northern sill at about 4 h after high water hw the mechanism leading to their generation is not clear these waves could propagate eastwards all along the strait and or northwestwards along the western spanish coast they could be responsible for the solitary type events observed at the eastern entrance of the strait at about 7 h after hw by ziegenbein 1969 1970 these events are noticeable in the hydrological parameters time series of armi and farmer 1988 and in the high rate current data 2 min apart from their april 1986 cruise besides these alongstrait waves our sar data show the existence of cross strait waves and give an idea of their wavelength and speed of propagation their presence leads to perturbations in the current revealed by simultaneous current data at the camarinal sill and north of cape cires

an inversion strategy for hydraulic tomography coupling travel time and amplitude inversion summary we present a hydraulic tomographic inversion strategy with an emphasis on the reduction of ambiguity of hydraulic travel time inversion results and the separation of the estimated diffusivity values into hydraulic conductivity and specific storage our tomographic inversion strategy is tested by simulated multilevel interference slug tests in which the positions of the sources injection ports and the receivers observation ports isolated with packers are varied simulations include the delaying effect of wellbore storage on travel times which are quantified and shown to be of increasing importance for shorter travel distances for the reduction of ambiguity of travel time inversion we use the full travel time data set as well as smaller data subsets of specified source receiver angles the inversion results of data subsets show different resolution characteristics and improve the reliability of the interpretation the travel time of a pressure pulse is a function of the diffusivity of the medium between the source and receiver thus it is difficult to directly derive values for hydraulic conductivity and specific storage by inverting travel times in order to overcome this limitation we exploit the great computational efficiency of hydraulic travel time tomography to define the aquifer structure which is then input into the underlying groundwater flow model modflow 96 finally we perform a model calibration amplitude inversion using the automatic parameter estimator pest enabling us to separate diffusivity into its two components hydraulic conductivity and specific storage

thermal genesis of dissolution caves in the black hills south dakota jewel cave 118 km of mapped passages beneath an area of 2 7 km 2 and wind cave 70 km beneath 1 8 km 2 are respectively the fourth and tenth longest known cave systems and the world9s foremost examples of three dimensional rectilinear networks of solutional passages other caves in the black hills are similar they occur in 90 140 m of well bedded mississippian limestone and dolomite walls throughout jewel cave are lined with euhedral calcite spar as much as 15 cm thick wind cave displays lesser encrustations and remarkable calcite boxwork since 1938 opinion has favored cave excavation by slowly circulating meteoric waters in artesian confinement similar to that surrounding the black hills we believe that the caves were developed by regional thermal waters focusing on paleospring outlets in outlying sandstones four sets of criteria are evaluated 1 morphological the three dimensional one phase maze form having convectional features is similar to known and supposed thermal caves in europe 2 petrographic and mineralogical study of the chief precipitates shows a record of carbonate solution calcite precipitation consonant with a model of cooling then degassing waters 3 a thermal anomaly at regional hot springs is shown to extend beneath wind cave where basal lake water samples show chemical and isotopic affinities with the thermal waters and 4 13 c and 18 o measurements place all suspected paleothermal water precipitates in the domain of thermal calcites reported by others and being deposited at the modern hot springs finally u series dates show that the wind cave deposits are quaternary and that the cave is still draining jewel cave is truly relict and divorced from the modern thermal ground water system its great calcite spar sheets are probably older than 1 25 1 50 ma

cathedral cave wellington caves new south wales australia a multiphase non fluvial cave cathedral cave is an outstanding example of a class of multiphase caves with largely non fluvial origins it contains large cavities such as cathedrals and cupolas characteristic of excavation by convection currents in rising waters smaller scale features such as rising half tubes pseudonotches curved juts projecting corners blades and bridges indicate intersection and exhumation of older cavities during the formation of younger ones it is possible to recognize at least ten significant phases of speleogenesis by morphostratigraphy in addition to the four generations of cave filling palaeokarst deposits intersected by the cave the cave we see today results from the progressive integration of a number of previously disconnected or poorly connected solution cavities copyright 2007 john wiley sons ltd

origin and morphology of limestone caves limestone caves form along ground water paths of greatest discharge and solutional aggressiveness flow routes that acquire increasing discharge accelerate in growth while others languish with negligible growth as discharge increases a maximum rate of wall retreat is approached typically about 0 01 0 1 cm yr determined by chemical kinetics but nearly unaffected by further increase in discharge the time required to reach the maximum rate is nearly independent of kinetics and varies directly with flow distance and temperature and inversely with initial fracture width discharge gradient and pco2 most caves require 104 105 yr to reach traversable size their patterns depend on the mode of ground water recharge sinkhole recharge forms branching caves with tributaries that join downstream as higher order passages maze caves form where 1 steep gradients and great undersaturation allow many alternate paths to enlarge at similar rates or 2 discharge or renewal of undersaturation is uniform along many alternate routes flood water can form angular networks in fractured rock anastomotic mazes along low angle partings or sponge work where intergranular pores are dominant diffuse recharge also forms networks and spongework often aided by mixing of chemically different waters ramiform caves with sequential outward branches are formed mainly by rising thermal or h2s rich water dissolution rates in cooling water increase with discharge co2 content temperature and thermal gradient but only at thermal gradients of more than 0 01 c m can normal ground water co2 form caves without the aid of hypogenic acids or mixing artesian flow has no inherent tendency to form maze caves geologic structure and stratigraphy influence cave orientation and extent but alone they do not determine branch work versus maze character

reconstruction of palaeoclimate in shalaii cave se of sangaw kurdistan province of iraq abstract shalaii cave is a closed system cave that contains old and active speleothems it is located on the northeast limb of the ashdagh anticline in sangaw district in northeastern iraq the study presents new data on cave monitoring and the geochemistry of stalagmite archives relevant for the palaeoclimate of iraq an extensive cave monitoring program was conducted from june 2014 to march 2015 which included analyses of cave air temperature relative humidity cave air dripwater and modern calcite precipitates on glass slides physical parameters were measured monthly and continuously using data loggers and meteorological data rainwater and dripwater samples were acquired for stable isotope analyses and hydrochemistry analysis stable isotopes of oxygen and carbon and absolute dating of u th series dating was used to determine palaeoclimate conditions the microclimate of shalaii cave during the studied period june 2014 to march 2015 the average temperature at the entrance point and inside the monitored cave was 17 05 c and 20 18 c respectively the relative humidity at the entrance point and inside the cave was 66 6 and 100 respectively eleven samples of dripwater and five samples of rainwater were acquired for isotope analyses and thirteen samples of dripwater for hydrochemical analysis from the environmental isotopes analysis 2h and 18o all water samples fall between the global meteoric water line gmwl and sangaw meteoric water line smwl the precipitation samples plot well above the gmwl the mechanism of recharge is direct recharge two stalagmites shc 01 and shc 02 were sampled from the cave the first sample shc 01 is dated from 1012 42 to 494 29 yr b p and the second sample shc 02 dates between 8025 38 to 6977 219 yr b p oxygen and carbon isotope results show that there are two climate conditions for palaeoclimate reconstruction in the sangaw district conditions were generally wetter and colder during 8025 38 to 6977 219 yr b p than current conditions from 1012 42 to 494 29 yr b p drier and warmer conditions prevail more similar to today

geomorphology and natural hazards in karst areas a review 1 introductionsince human beings started to colonise the world slowly migrat ing in multiple directions from the african rift and ultimatelyreaching the southernmost territories of the americas they haveinteracted with the natural environment using its resources and suf fering from its hazardous processes survival of mankind was possiblethanks to its ability to adapt to an ever changing environment and itscapability to learn and communicate the new ndings from the ear liest times geomorphic features and processes were an essential partof social survival crozier et al 2011 in karst terrains caves wereused as shelters as well as burial and sacred places playing an instru mental role in the day to day struggle for survival especially duringthe ice ages fig 1 spectacular karst landmarks such as big cave en trances blue karst springs deep collapse sinkholes cenotes or rockarches just to name a few have often become part of the naturaland supernatural heritage of our ancestors in prehistoric times the human impact on the karst environmentwas very limited like the probability of properties and people beingdamaged by karst processes e g subsidence ooding both impactsandhazardsinkarstterrainshaveincreaseddramaticallyover thelasttwo centuries along with the exponential increase in population andour capability to modify the natural environment largely related tothe economic and technological development of the societies an in creasing number of scientists consider that humans are nowadaysthe most effective geomorphic agent and a prime factor in landscapeevolution zalasiewicz et al 2010 price et al 2011 in fact the for mal de nition of the anthropocene as a new epoch of the geologicaltime scale characterised by a signi cant and global human impact onthe earth s ecosystems is being debated at the present time around25 of the earth s population lives on or nearby karst areas ford andwilliams 2007 and the increasing exploitation of karst resources such as water and building material is leading to severe environmen tal impacts and unsustainable situations drew and hotzl 1999 gunn 2004 unfortunately the number of karst areas affected bywater pollution landscape degradation and other impacts is growingveryrapidly additionally thedamagecausedbyhazardouskarstpro cesses especially subsidence sinkholes beck 2003 waltham et al 2005 gutierrez et al 2008a will most likely keep on increasing exposed human elements augment and anthropogenic changes inthe karst systems frequently result in hazard enhancement karstgeomorphologists and hydrologists can play a decisive role in pre venting natural disasters in karst areas particularly those inducedby human activities dams with leakage and sinkhole problems milanovic 2000 cooper and gutierrez 2011 mines and tunnelsaffected by ooding and subsidence li and zhou 1999 autin 2002 casagrandeet al 2005 luchaetal 2008 high speedrailwaysbuilt in sinkhole prone areas guerrero et al 2008 or developmentof sinkholes at huge rates induced by lake level yechieli et al 2006 or water table sprynskyy et al 2009 declines the importance of properly managing karst areas and mitigatingthe detrimental effects caused by human activities on these inherentlysensitive environments has been boosted by a series of conferencesand projects since the early 1990s ford 1993 williams 1993 pariseet al 2008 2009 raising public awareness on the need to protectour endangered natural resources especially in developed countries has promoted the production of karst speci c environmental impactassessments veni 1999 recently severalapproacheshavebeenpro posedtoassessthedegreeofhuman induceddisturbanceinkarstareas van beynen and townsend 2005 calo and parise 2006 de waele 2009 north et al 2009 although these studies are essential for apropermanagementofthekarstresources theymaybefutileifnotfol lowed by adequate administrative decisions and regulations 2 karst geomorphology2 1 karst processeskarst is characterised by the predominance of rock dissolution overmechanical erosion and is typical of present temperate cold andwarm and tropical environments ford and williams 2007 in karstterrains surface and subsurface geomorphology and hydrology arelargely governed by dissolution of carbonate and or evaporite rocks in the most classical common situation surface waters acidi ed byco

evidence of multimodal structure of the baroclinic tide in the strait of gibraltar 1 the multimodal structure of the baroclinic tides in the strait of gibraltar is studied using observations and numerical simulations observational data and model results revealed the presence of two types of tidal internal waves generated over camarinal sill cs one propagates toward the mediterranean and disintegrates into series of nonlinear short internal waves with amplitudes of 50 m and more the second type behind the first propagates slower and has a longer wavelength the vertical structure with both upward and downward displacements of isopycnals can be identified as a manifestation of higher baroclinic modes analysis of the empirical orthogonal functions of the adcp measurements performed over cs and model time series has shown that the second baroclinic mode predominates in the second type of internal waves its amplitude can reach one third that of the first baroclinic mode of the leading waves of depression

structural and host rock controls on the distribution morphology and mineralogy of speleothems in the castanar cave spain t he casta nar cave central western spain formed in mixed carbonate siliciclastic rocks of neoproterozoic age the host rock is finely bedded and shows a complex network of folds and fractures with a prevalent n150e strike this structure controlled the development and the maze pattern of the cave as well as its main water routes the cave formed more than 350 ka ago as the result of both the dissolution of interbedded carbonates and weathering of siliciclastic beds which also promoted collapse of the overlying host rock at present it is a totally vadose hypergenic cave but its initial development could have been phreatic the cave s speleothems vary widely in their morphology and mineralogy in general massive speleothems stalactites stalagmites flowstones etc are associated with the main fractures of the cave and bedding planes these discontinuities offer a fairly continuous water supply other branching fibrous mostly aragonite speleothems commonly occur in the steeper cave walls and were produced by capillary seepage or drip water detailed petrographical and isotope analyses indicate that both aragonite and calcite precipitated as primary minerals in the cave waters primary calcite precipitated in waters of low magnesium content whereas aragonite precipitated from magnesium rich waters differences in isotope values for calcite 5 2 for 18 oa nd 9 6 for 13 c and aragonite 18 oo f 4 5 and 13 co f 3 5 can be explained by the fact that the more unstable mineral aragonite tends to incorporate the heavier c isotope to stabilize its structure or that aragonite precipitates in heavier waters changes in the water supply and the chemistry and instability of aragonite caused 1 inversion of aragonite to calcite which led to the transformation of aragonite needles into coarse calcite mosaics 2 micritization which appears as films or crusts of powdery opaque calcite and 3 dissolution dolomite huntite magnesite and sepiolite were identified within moonmilk deposits and crusts moonmilk occurs as a soft white powder deposit on different types of speleothems but mostly on aragonite formations huntite and magnesite formed as primary minerals whereas dolomite arose via the replacement of both huntite and aragonite owing to its variety of speleothems and location in an area of scarce karstic features the casta nar cave was declared a natural monument in 1997 and is presently the target of a protection and research programme although the main products formed in the cave and their processes are relatively well known further radiometric data are needed to better constrain the timing of these processes for example it is difficult to understand why some aragonite speleothems around 350 ka old have not yet given way to calcite which indicates that the environmental setting of the cave is still not fully understood

mixing at camarinal sill in the strait of gibraltar during the gibraltar experiment in 1985 1986 observations of shear stratification microstructure and acoustic backscatter revealed a complex mixing regime at camarinal sill in the strait of gibraltar the mixing is forced by strong semidiurnal tidal currents and weaker but more steady baroclinic flows flows are characterized as outflow or inflow nearly equivalent to westward or eastward rising water at gibraltar coincides with outflow at all depths we observed two modes of outflow at the sill in may 1986 the transition layer separating atlantic and mediterranean water was between 0 75 mpa and 1 mpa when we sampled east of the sill near neap tide the transition turned down just before reaching the sill crest where the flow became critical increasing shear soon destabilized the transition producing billows which grew to 30 75 m on the west flank of the sill the overturning generated intense turbulence with peak dissipation rates e exceeding 10 2 w kg 1 this turbulence rapidly thickened the transition from z 30 50 m east of the sill to z 130 150 m within 1 2 km west of the sill from the rate of thickening we estimate the rate of formation of new transitional water during neap tide as 0 8 1 2 105 m3 s 1 this outflow mode did not release eastward propagating internal bores when outflow turned to inflow but the inflow did appear to arrest the deep outflow in may the largest average dissipation rate over and just west of the sill had the same magnitude as estimates of the net energy lost by adjustment of velocity and mass across the sill during outflow other averages are smaller than the energy loss presumably because the limited sampling severely underestimates the average dissipation rate during outflow strong shears were observed to rise to 100 times those in the background internal wave field however probably owing to spatial offsets between the ship s acoustic doppler current profiler and our tethered free fall profiler the only statistically significant correlations were found between overturning scales measured directly and those estimated from e in the same profile we observed the other outflow mode in october 1985 when we profiled over the sill near spring tide and the transition was east of the sill centered near 1 5 mpa after encountering the sill the transition rose sharply and remained within 10 20 m of the surface across the sill plunging steeply downward just past the west edge of the sill this was accompanied by intense turbulence and at least one rebound of the transition we did not observe release of eastward propagating bores when inflow turned to outflow but observations by armi and farmer 1988 in april 1986 found bores released at spring tide in regimes similar to the one we observed in october 1985

calcite and aragonite precipitation under controlled instantaneous supersaturation elucidating the role of caco3 saturation state and mg ca ratio on calcium carbonate polymorphism abstract for many decades researchers have attempted to clarify the factors controlling the precipitation of calcium carbonate polymorphs and the incorporation of mg into calcite precipitating in natural systems in this study a novel experimental approach delineates the role of instantaneous supersaturation and solution mg ca ratio in calcium carbonate mineralogy and composition the results of this study show that in solutions with different mg ca ratios the transition between the aragonite and the calcite aragonite precipitation fields is controlled by a combination of the saturation state of the solution with respect to caco3 and the mg ca ratio in solution the data show that for increasing solution mg ca ratios progressively higher supersaturation level is required for calcite precipitation the predominance of aragonite at high solution mg ca and low supersaturations is attributed to a relative decrease in calcite growth rates as a result of increasing incorporation of mg2 in the calcite lattice at higher solution mg ca ratios as suggested by abundant experimental work increasing solution mg ca decreases the growth rate of calcite while aragonite growth rates stay unaffected our experiments do demonstrate that despite decreased growth rate the percentage of mgco3 in calcite increases with increasing solution mg ca ratio as calcite growth rates decrease aragonite growth rates stay constant and it becomes the dominant mineral phase in solutions with high mg ca ratio and low supersaturations these findings are relevant to present day mineralogical distributions in carbonate systems and might be the key to elucidate the environmental conditions responsible for mineralogic changes through geologic time the observed dependence of calcium carbonate mineralogy on solution composition and supersaturation suggests that carbonate mineralogy is controlled by kinetics of growth

the importance of sub mesoscale processes for the exchange of properties through the strait of gibraltar abstract this article presents a detailed analysis of the sub mesoscale transport processes in the strait of gibraltar the interest is focussed on the camarinal sill region and special attention is paid to the across strait transport processes the divergences and convergences in the central zone and the small scale circulation patterns along the northern coastal margin the analysis is based on high resolution 7 m sst images acquired by an air borne hyper spectral scanner and has been complemented with a rhodamine release experiment continuous thermo salinograph records acoustic doppler current adcp profiles from both moorings and vessel mounted experiments and numerical modelling it is deduced from the analysis that the coupling between the upwelling processes induced by the internal tide and the generation of large amplitude internal waves and the cyclonic eddies formed on the coastal margin seems to be the mechanism that explains the chlorophyll maxima frequently found on the coastal margin of the studied area further as a consequence of the small scale patterns of circulation induced by the internal waves the suspended substances are displaced from the coastal margins toward the central zones and later are carried by the westward current toward the convergence zones created by the internal waves where they may be retained and accumulate then in the eastward phase of the tidal current over the camarinal sill these nuclei of concentrated substances nutrients chlorophyll and plankton are transported toward the alboran sea where they must contribute in part to the primary productivity there

aquifer heterogeneity characterization with oscillatory pumping sensitivity analysis and imaging potential 1 periodic pumping tests in which a fluid is extracted during half a period then reinjected have been used historically to estimate effective aquifer properties in this work we suggest a modified approach to periodic pumping test analysis in which one uses several periodic pumping signals of different frequencies as stimulation and responses are analyzed through inverse modeling using a steady periodic model formulation we refer to this strategy as multifrequency oscillatory hydraulic imaging oscillating pumping tests have several advantages that have been noted including no net water extraction during testing and robust signal measurement through signal processing through numerical experiments we demonstrate additional distinct advantages that multifrequency stimulations have including 1 drastically reduced computational cost through use of a steady periodic numerical model and 2 full utilization of the aquifer heterogeneity information provided by responses at different frequencies we first perform fully transient numerical modeling for heterogeneous aquifers and show that equivalent results are obtained using a faster steady periodic heterogeneous numerical model of the wave phasor the sensitivities of observed signal response to aquifer heterogeneities are derived using an adjoint state based approach which shows that different frequency stimulations provide complementary information finally we present an example 2 d application in which sinusoidal signals at multiple frequencies are used as a data source and are inverted to obtain estimates of aquifer heterogeneity these analyses show the different heterogeneity information that can be obtained from different stimulation frequencies and that data from several sinusoidal pumping tests can be rapidly inverted using the steady periodic framework

the role of condensation in the evolution of dissolutional forms in gypsum caves study case in the karst of sorbas se spain abstract the karst of sorbas se spain is one of the most important gypsum areas worldwide its underground karst network comprises over 100 km of cave passages rounded smooth forms condensation cupola and pendant like features appear on the ceiling of the shallower passages as a result of gypsum dissolution by condensation water meanwhile gypsum speleothems formed by capillarity evaporation and aerosol deposition such as coralloids gypsum crusts and rims are frequently observed closer to the passage floors the role of condensation dissolution mechanisms in the evolution of geomorphological features observed in the upper cave levels has been studied by means of long term micro erosion meter mem measurements direct collection and analysis of condensation waters and micrometeorological monitoring monitoring of erosion at different heights on gypsum walls of the cueva del agua reveals that the gypsum surface retreated up to 0 033 mm yr 1 in mem stations located in the higher parts of the cave walls the surface retreat was negligible at the lowest sites suggesting higher dissolution rates close to the cave ceiling where warmer and moister air flows monitoring of microclimatic parameters and direct measurements of condensation water were performed in the covadura cave system in order to estimate seasonal patterns of condensation direct measurements of condensation water dripping from a metal plate placed in the central part of the el bosque gallery of covadura cave indicate that condensation takes place mainly between july and november in coincidence with rainless periods the estimated gypsum surface lowering due to this condensation water is 0 0026 mm yr 1 microclimatic monitoring in the same area shows differences in air temperature and humidity of the lower parts of the galleries colder and drier with respect to the cave ceiling warmer and wetter this thermal sedimentation controls the intensity of the condensation evaporation mechanisms at different heights in the cave

internal waves in a stratified shear flow the strait of gibraltar abstract the wavelengths directions and phase speeds of internal waves propagating through the strait of gibraltar were measured from shore based marine radar images of their surface features shipborne echo sounder images identified these waves as first mode and enabled their amplitudes to be measured the moving features in the radar images were closely correlated with the waves in the echo sounder image a numerical solution of the taylor goldstein equation was used to predict the phase speed of the waves utilizing simultaneous measurements of the density and velocity structure of the water column within the bounds of experimental error there was good agreement between the theoretical and measured phase speeds of the waves on two different tidal cycles no correlation appeared to be present between amplitude and estimated wave width indicating that the waves were not behaving as korteweg devries type solitons

the gruta de las maravillas aracena south west iberia setting and origin of a cave in marbles from dissolution of pyrite abstract the gruta de las maravillas cave is located at the wnw side of the cerro del castillo hill in aracena huelva sw spain the cavity is hosted within marbles included in a strip of high grade metamorphic rocks belonging to the so called aracena massif in the southernmost ossa morena zone the hill is made up of granodiorites marbles quartzites and gneisses with the foliation trending n110 e and dipping roughly 60 80 towards ne the marbles appear highly deformed in ductile conditions with isoclinal folds of different sizes boudins porphyroblasts with sigmoidal morphology and left lateral s c shear fabrics close to the granodiorite contact the marbles include a thin band of disseminated and massive pyrite partially transformed to fe oxides analysis of the brittle deformation and the associated paleostresses indicates a ne sw oriented maximum compression probably related to the latest variscan collisional tectonics 300 ma late carboniferous the gruta de las maravillas is divided into three main levels located at 650 665 and 685 m a s l the dissolution having progressed from top to bottom in different stages of stability of the water table the initial dissolution phases were probably favoured by the presence of pyrite in the host rock which in turn would have caused acidification of the circulating water favouring this hypothesis a thin layer of fe oxides locally including gypsum covers some parts of the cave walls the morphology and structure of the cavity result from interaction between the general nne dipping foliation with sub perpendicular joints the pyrite bearing band in the host marbles and the descending water table

loss of primary texture and geochemical signatures in speleothems due to diagenesis evidences from castanar cave spain geochemical signals from speleothems are commonly used in the investigation of palaeoenvironments in most cases however little attention is paid to whether or not these signals are primary or altered by diagenesis the speleothems of the castanar cave caceres spain which are initially formed of calcite or aragonite have undergone a variety of meteoric diagenetic processes such as micritization and neomorphism inversion that collectively modify their primary features textures mineralogy geochemical signals the mean 13c and 18o values of the aragonites in the cave are 8 66 and 4 64 respectively whereas the primary calcites have mean 13c and 18o values of 9 99 and 5 77 respectively following the diagenetic process of micritization the aragonite isotopic signals averaged 7 63 13c and 4 74 18o and the calcite micrite signals 9 53 13c and 5 21 18o where inversion took place some secondary calcites after the aragonite show preserved aragonite whereas others do not the secondary calcites without aragonite relics show isotopic values slightly higher than those of the primary calcite due to the inheritance of the aragonite signal where aragonite relics are preserved the isotopic signatures are very similar to those of the aragonite micrite in addition the stable isotopic values and sr and mg contents of the speleothems became also modified by micritization and or inversion these diagenetic processes were driven by the changes in composition of the cave waters over time and space but also in the case of aragonite by its initial unstable mineralogy the present results highlight how important diagenesis is in caves and how the initial features of cave minerals may be lost these changes alter the geochemical signals shown by speleothems which may have an impact on the interpretation of the results obtained in palaeoenvironmental studies

3 d transient hydraulic tomography in unconfined aquifers with fast drainage response we investigate through numerical experiments the viability of three dimensional transient hydraulic tomography 3dtht for identifying the spatial distribution of groundwater flow parameters primarily hydraulic conductivity k in permeable unconfined aquifers to invert the large amount of transient data collected from 3dtht surveys we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasilinear geostatistical formulas of kitanidis in order to base our numerical experiments around realistic scenarios we utilize pumping rates geometries and test lengths similar to those attainable during 3dtht field campaigns performed at the boise hydrogeophysical research site bhrs we also utilize hydrologic parameters that are similar to those observed at the bhrs and in other unconsolidated unconfined fluvial aquifers in addition to estimating k we test the ability of 3dtht to estimate both average storage values specific storage ss and specific yield sy as well as spatial variability in storage coefficients the effects of model conceptualization errors during unconfined 3dtht are investigated including 1 assuming constant storage coefficients during inversion and 2 assuming stationary geostatistical parameter variability overall our findings indicate that estimation of k is slightly degraded if storage parameters must bemore jointly estimated but that this effect is quite small compared with the degradation of estimates due to violation of structural geostatistical assumptions practically we find for our scenarios that assuming constant storage values during inversion does not appear to have a significant effect on k estimates or uncertainty bounds less

speleogenetic history of the hungarian hydrothermal karst the hydrothermal karst of hungary displays at least two principal stages of development in two differing environments caves of an early stage were formed within a deep zone of low thermal gradient these caves vugs are small tens of centimeters and lined with scalenohedral crystals of calcite that are often in association with barite calcite yields fluid inclusion temperatures of 55 95 c and is depleted in18o 11 2 to 17 6 per mil pdb the caves were formed by ascending thermal waters charged with co2 solubility of caco3 in such a system gradually increases with the ascent of the fluid solutional zone but drops sharply at a depth of 250 m to 500 m below the water surface depositional zone caves formed in the solutional zone may be shifted into the depositional zone due to tectonic uplift and calcite lines their walls large caves tens to thousands of cubic meters of a late stage were formed within a shallow zone of high thermal gradient immediately below and above the thermal water table the calcite of the phreatic crusts has a rhombohedral habit displays lower fluid inclusion temperatures 35 55 c and less and a depletion in18o of 9 5 to 14 6 per mil pdb several powerful cave forming processes may operate there including convection mixing cooling corrosion and condensation corrosion due to differences in the rate of tectonic uplift rate of hydrothermal system decay and hydrogeologic pattern these caves were either filled with water for a long period of time phreatic calcite crusts are formed or partly dewatered early in their history waterline and subaerial speleothems are formed the zones of thermal cave formation recognized in hungary may have a universal character very similar features are found in other hydrothermal karst areas of the world kirghizia algeria south dakota

internal waves in the strait of gibraltar and their role in the vertical mixing processes within the bay of algeciras abstract this article presents some of the results of an oceanographic survey carried out in the bay of algeciras strait of gibraltar as part of a research project intended to assess the environmental quality of the bay one of the most interesting findings was the step like patterns presented by density profiles within the bay which were indicative of notable vertical mixing activity there the analysis of the observations indicates that those mixing processes may be explained by the interaction between the local internal tide dynamics and the large amplitude internal waves entering the bay which seem to originate from the camarinal sill region

validation of hydraulic tomography in an unconfined aquifer a controlled sandbox study in this study we demonstrate the effectiveness of hydraulic tomography ht that considers variably saturated flow processes in mapping the heterogeneity of both the saturated and unsaturated zones in a laboratory unconfined aquifer the successive linear estimator sle developed by mao et al 2013c for interpreting ht in unconfined aquifers is utilized to obtain tomograms of hydraulic conductivity k specific storage ss and the unsaturated zone parameters pore size parameter and saturated water content s for the gardner russo s model the estimated tomograms are first evaluated by visually comparing them with stratigraphy visible in the sandbox results reveal that the ht analysis is able to accurately capture the location and extent of heterogeneity including high and low k layers within the saturated and unsaturated zones as well as reasonable distribution patterns of and s for the gardner russo s model we then validate the estimated tomograms through predictions of drawdown responses of pumping tests not used during the inverse modeling effort the strong agreement between simulated and observed drawdown curves obtained by pressure transducers and tensiometers demonstrates the robust performance of ht that considers variably saturated flow processes in unconfined aquifers and the unsaturated zone above it in addition compared to the case using the homogeneous assumption ht results as expected yield significantly better predictions of drawdowns in both the saturated and unsaturated zones this comparison further substantiates the unbiased and minimal variance of ht analysis with the sle algorithm

periodic pumping tests summary we performed pumping tests with a periodic succession of injection and production intervals in a field of three shallow boreholes penetrating a jointed sandstone formation tests were conducted at periods ranging from 10 to 5400 s and pumping rates between 5 and 20 l min 1 two types of analysis for the periodic pumping tests are presented injectivity analysis rests on the determination of the amplitude ratio and phase shift between the periodic flow rate and pressure records from the pumping well interference analysis is based on an evaluation of attenuation and phase shift between the periodic pressure signals at the pumping and monitoring wells a periodic excitation permits to employ standard signal processing tools such as fast fourier transformation facilitating the evaluation of weak signals the observed amplitude ratio and phase shift values are compared to analytical predictions of 1 d and radial flow models results of interference tests are particularly diagnostic for the applicability of a subsurface model our test results do not fully agree with any of the considered analytical models suggesting a heterogeneous subsurface we suppose that the two analysis methods yield averaged hydraulic properties of different volumes of a heterogeneous subsurface periodic injectivity tests screen the subsurface to increasing penetration depth if pumping period is systematically increased while the subsurface volume between pumping and monitoring well dominates the outcome of an interference test at all periods periodic pumping provides several operational advantages compared to conventional testing such as drawdown pulse or shut in tests periodic testing can be superposed on a long term operation reducing operational conflicts and permitting continuous monitoring of changes in subsurface properties processing of periodic signals provides results even in a field with strong transient changes in fluid pressure related for example to operations in nearby wells periodic pumping can be performed in a closed loop minimizing the total fluid volume involved

aquifer imaging with pressure waves evaluation of low impact characterization through sandbox experiments understanding the detailed spatial variation of hydraulic properties in the subsurface has been the subject of intensive research over the past three decades a recently developed approach to characterize subsurface properties is hydraulic tomography in which a series of pumping tests are jointly inverted using a heterogeneous numerical model recently cardiff et al 2013 proposed a modified tomography approach named oscillatory hydraulic tomography oht in which periodic pumping signals of different frequencies serve as the aquifer stimulation and pressure responses are recorded at observation locations for tomographic analysis its key advantages over traditional hydraulic tomography are that 1 there is no net injection or extraction of water and 2 the impulse an oscillatory signal of known frequency is easily extracted from noisy data however oht has only been evaluated through numerical experiments to date in this work we evaluate oht performance by attempting to image known heterogeneities in a synthetic aquifer an instrumented laboratory sandbox is filled with material of known hydraulic properties and we measure aquifer responses due to oscillatory pumping stimulations at periods of 2 5 10 and 20 s pressure oscillation time series are processed through fourier transforms and inverted tomographically to obtain estimates of aquifer heterogeneity using a fast steady periodic groundwater flow model we show that oht is able to provide robust estimates of aquifer hydraulic conductivity even in cases where relatively few pumping tests and observation locations are available the use of multiple stimulation frequencies is also shown to improve imaging results

dolomite in caves recent dolomite formation in oxic non sulfate environments castanar cave spain abstract dolomite is a common mineral in the rock record but rare in recent superficial environments where it does occur it is related to anoxic sulfate rich environments and microbial activity the occurrence of some dolomite deposits in caves however indicates that dolomite formation is also possible in oxic non sulfate settings dolomite is forming at 17 c and in oxic vadose conditions on the host rocks and aragonite speleothems of the castanar cave caceres spain it appears as spheroids and dumbbells 50 300 m in diameter that internally consist of micron sized rhombic to rounded crystals initially this dolomite is ca rich non stoichiometric and poorly ordered mg rich solutions allow the precipitation of metastable mg rich carbonates such as huntite this soon transforms into this ca rich dolomite which later ages to form a more stoichiometric dolomite these dolomites show similarities to those grown under anoxic sulfate rich conditions and their presence in caves provides a different setting that may contribute to the understanding of the dolomite problem including their initial formation and later recrystallization processes

determination of hydrogeological parameters using sinusoidal pressure tests a theoretical appraisal a method for determining the hydrogeologic parameters of formations of interest based on a sinusoidal pressure fluctuation in an excitation borehole is proposed equations are derived which describe the dependence of pressures and phase lags outside the excitation borehole on distance signal frequency specific storage hydraulic conductivity and flow rates these cover 2 distinct configurations that of a point source deep within a water saturated elastic formation and that of a line source totally penetrating a confined aquifer the ranges of application of these 2 arrangements are appraised using existing data on hydraulic diffusivities to derive likely excitation and response pressures for various flow rates and signal frequencies the 2 configurations require the accurate measurement of phase shifts in the case of the point source and of amplitude in the line source case and it is concluded that the ranges of applications are useful but limited 20 references

aragonite calcite relationships in speleothems grotte de clamouse france environment fabrics and carbonate geochemistry abstract in grotte de clamouse france aragonite forms in a variety of crystal habits whose properties reflect the conditions of formation prolonged degassing and evaporation yield needle aragonite which is more enriched in 18o and 13c than aragonite ray crystals which form near isotopic equilibrium at present aragonite ray crystals form at the tops of stalagmites at very low discharge 0 00035 ml min and when fluid mg ca ratio is 1 1 temperature and evaporation do not seem to have a significant role in their formation the presence of aragonite in stalagmites should be indicative of a decrease in drip rate related to either dry climate conditions or local hydrology fossil aragonite was in part replaced by calcite in a time frame 13c signal and u content and preserved aragonite relicts up to 16 weight the isotope signal of different aragonite habits may reflect conditions of formation rather than climate parameters the real extent of aragonite to calcite transformation may be underestimated when replacement calcite inherits both textural and chemical properties of the precursor

stable isotope composition alteration produced by the aragonite to calcite transformation in speleothems and implications for paleoclimate reconstructions abstract aragonite a mineralogical constituent of speleothems in cave environments is unstable and susceptible to inversion to calcite a diagenetic process that involves changes in the mineralogy texture and geochemistry of speleothems however the exact alterations of stable isotope compositions during such diagenesis have not been fully investigated in this study two aragonite stalagmites sn3 and sn15 from the shennong cave southeast china were found partially inverted to calcite as determined by x ray diffraction xrd and scanning electron microscopy sem analyses and thin section inspections under microscope the fiber relics and textural ghosts of aragonite preserved in coarse and equant mosaic calcite crystals clearly indicate that the calcite in these two stalagmites were inverted from aragonite the stable isotope compositions 13 c and 18 o given in per mil versus vpdb standard of primary aragonite and secondary calcite were analyzed and compared along both growth layers and growth axes the results show that along growth layers differences of 13 c values between aragonite and calcite are negligible 0 1 0 2 whereas differences of 18 o values between aragonite and calcite are significant 0 63 0 87 comparisons along growth axes show similar results i e differences of 13 c values are negligible 0 06 0 22 whereas differences of 18 o values are significant 0 85 0 29 most likely the aragonite in sn3 and sn15 were internally inverted by interactions of trace calcite crystallites and pore water within intercrystalline pore spaces by a dissolution reprecipitation process occurring in trapped pore water in the case of the inversion of aragonite to calcite in speleothems such as that observed in sn3 and sn15 the 13 c values could be used in paleoclimate and paleoenvironment reconstructions because they are inherited from those of primary aragonite although the 18 o values might be cross calibrated to those of primary aragonite if the aragonite calcite fractionation offset is known e g 0 85 0 29 in this study however the 18 o values of secondary calcite should be used with caution in such reconstructions as the 18 o offset value is not consistently invariable

characterizing co2 plumes in deep saline formations comparison and joint evaluation of time lapse pressure and seismic tomography abstractmonitoring the migration of sequestered co2 in deep heterogeneous reservoirs is inherently difficult geophysical methods have been successfully used but flow conditions are only indirectly linked to the measured properties besides geophysical methods pressure tomography pt is proposed as an alternative method to depict the structure of deep saline formations for co2 sequestration and to continuously delineate co2 plumes in contrast to more established geophysical measurements pressure transients are directly related to flow properties which allows for the estimation of permeability we investigate the influence of aquifer heterogeneity on pt performance and we compare the pt results to crosshole seismic tomography st multilevel fluid injections and high frequency p wave pulses are induced in a simulated deep borehole and the recorded signals at another well are processed by a traveltime inversion scheme the reservoir structure is inferred by clustering the inverted hydraulic diffusi

numerical modeling of the semidiurnal tidal exchange through the strait of gibraltar 1 a three dimensional sigma coordinate free surface model is used to investigate the semidiurnal tidal exchange through the strait of gibraltar the model makes use of a coastal following curvilinear orthogonal grid that includes the gulf of cadiz and the alboran sea with very high resolution in the strait 500 m a lock exchange initial condition is used the western part of the model domain is filled with atlantic water whereas the eastern part is filled with mediterranean water the model is forced at the open boundaries through the specification of the semidiurnal m2 and s2 tidal surface elevation the model is run over a spring neap cycle fortnightly period and the results are compared with available observed data simulated cotidal maps of the m2 and s2 tidal elevation components are in quantitative and qualitative good agreement with observed data as well as with the simulated major and minor axis of tidal ellipse the model reproduces the generation and the subsequent propagation of internal bores both eastward and westward showing that they are always generated during the fortnightly period however the principal aim of this work is to quantify the effects of tidal forcing on mean quantities entrainment and transport of atlantic and mediterranean water along the strait model results reveal that the contribution of the semidiurnal tidal component m2 to the transport is relevant over camarinal sill whereas it is negligible at the eastern end of the strait model results indicate also that the effect of the semidiurnal tide is to increment the mean transport by about 30 both for the inflow and the outflow

kinetic control of morphology composition and mineralogy of abiotic sedimentary carbonates abstract conventional thinking has long held that the abiotic precipitation of calcium carbonate occurs with a causal relationship between fluid my ca ratios and crystal morphology crystal composition and carbonate mineralogy resulting in the formation of meteoric equant low magnesium calcite and marine acicular high magnesium calcite and aragonite problematically calcites with varying amounts of incorporated magnesium occur either as equant or acicular crystals and aragonite may coexist with calcite in either environment commonly however a systematic relation exists between crystal morphology composition mineralogy and rates of reactant supply to growing crystal surfaces for example equant rather than acicular crystals of calcite form in modern deep and or cold marine meteoric phreatic and deep burial settings where the degree of carbonate saturation and or rates of fluid flow are low in areas of higher saturation and or fluid flow such as in warm shallow marine and meteoric vadose environments acicular calcite may predominate this relation is also seen in systems in which aragonite and calcite form in intimate association aragonite precipitation is favored when rates of reactant supply are high calcite forms when rates are low such relations suggest that crystal morphology composition and mineralogy are controlled by the kinetics of surface nucleation and the amount of reactants principally carbonate ions at growth sites precipitating phases are the ones which can best accommodate such excess reactants ambient mg ca ratios only indirectly control the nature of inorganically precipitated carbonate phases

internal tides in the strait of gibraltar abstract analysis of moored current measurements in the strait of gibraltar is provided here the vertical internal displacements double amplitudes with a semidiurnal frequency are extremely large and sometimes exceed 200 m it is found that these displacements are associated with forced tidal internal waves over camarinal sill which crosses the strait the separation of tidal components showed that the amplitude of internal tide with m2 frequency is 69 m while the amplitudes of other components of the internal tide s2 k1 o1 are 3 5 times smaller the amplitudes of the waves decrease with the distance from the sill and at a distance of 50 km from the sill the amplitudes are 3 times smaller than over the sill the energy of internal tides is transferred to internal bore and turbulent mixing the wavelength of the internal tide was estimated on the basis of moored measurements the wavelength of the east propagated wave is 90 km while the west propagated wave is 60 km numerical modeling demonstr

should hydraulic tomography data be interpreted using geostatistical inverse modeling a laboratory sandbox investigation the robust performance of hydraulic tomography ht based on geostatistics has been demonstrated through numerous synthetic laboratory and field studies while geostatistical inverse methods offer many advantages one key disadvantage is its highly parameterized nature which renders it computationally intensive for large scale problems another issue is that geostatistics based ht may produce overly smooth images of subsurface heterogeneity when there are few monitoring interval data therefore some may question the utility of the geostatistical inversion approach in certain situations and seek alternative approaches to investigate these issues we simultaneously calibrated different groundwater models with varying subsurface conceptualizations and parameter resolutions using a laboratory sandbox aquifer the compared models included 1 isotropic and anisotropic effective parameter models 2 a heterogeneous model that faithfully represents the geological features and 3 a heterogeneous model based on geostatistical inverse modeling the performance of these models was assessed by quantitatively examining the results from model calibration and validation calibration data consisted of steady state drawdown data from eight pumping tests and validation data consisted of data from 16 separate pumping tests not used in the calibration effort results revealed that the geostatistical inversion approach performed the best among the approaches compared although the geological model that faithfully represented stratigraphy came a close second in addition when the number of pumping tests available for inverse modeling was small the geological modeling approach yielded more robust validation results this suggests that better knowledge of stratigraphy obtained via geophysics or other means may contribute to improved results for ht

control variability and internal bore evolution in the strait of gibraltar a 2 d two layer model study a two dimensional high resolution non linear two layer free surface boundary fitted co ordinate hydrostatic model was applied to study the time space variability of hydraulic controls and the development of internal bores in the strait of gibraltar the model predicts the occurrence of four averaged over a tropical month controls located to the west of the spartel sill at the spartel and camarinal sills and in the tarifa narrows the last of these controls is apparent in the sense that it consists of discrete fragments alternating with subcritical flow regions the only control which extends over the whole width of the strait is the control at the camarinal sill but it breaks down during neap tide too this control exists concurrently with the control in the tarifa narrows for short periods while for much of the tropical month there is either just one or neither of the controls the model predicts the development of a hydraulic jump and a jump drop pair near the camarinal sill the appearance of bulges of mediterranean water to the east and west of the sill the large amplitude and small amplitude internal bores released from the camarinal sill which travel respectively eastward and westward and their transformation due to radial spreading and dissipative effects also presented here are the results illustrating the effects of earth s rotation on the internal bores in the strait of gibraltar

seismic reflection imaging of karst in the persian gulf implications for the characterization of carbonate reservoirs karstification positively and negatively affects the quality of carbonate reservoirs for example dissolution and brecciation can increase porosity and permeability whereas cavern collapse or cementation driven by postkarstification fluid flow may occlude porosity and reduce permeability karst may also pose challenges to drilling because of the unpredictable and highly variable porosity and permeability structure of the rock and the corresponding difficulty in predicting drilling mud weight when combined outcrop petrographic and geochemical data can constrain the style distribution and origin of seismic scale karst which may provide an improved understanding of carbonate reservoir architecture and allow development of safer drilling programs however relatively few studies have used seismic reflection data to characterize the regional development of seismic scale karst features in this study we use time migrated two dimensional seismic reflection data to determine the distribution scale and genesis of karst in a 3 km thick 9800 ft thick jurassic miocene carbonate dominated succession in the persian gulf we map 43 seismic scale karst features which are expressed as vertical pipe columns of chaotic reflections capped by downward deflected depressions that are onlapped by overlying strata the columns are up to 2 km 6500 ft tall spanning the upper jurassic to upper cretaceous succession and are up to 5 5 km 18 000 ft in diameter we interpret these pipes to have formed in response to hypogene karstification by fluids focused along preexisting faults with hypogene generated depressions enhanced by epigene processes during key intervals of exposure our study indicates that seismic reflection data can and should be used in conjunction with petrographic and geochemical techniques to determine the presence of hypogene karst plays and to help improve the characterization of carbonate reservoirs and associated drilling hazards

environmental controls on the petrology of a late holocene speleothem from botswana with annual layers of aragonite and calcite abstract a carbonate stalagmite from drotsky s cave in northwestern botswana consists of alternating layers of calcite and aragonite layer counts and radiocarbon ages indicate that the calcite aragonite pairs are annual layers representing about 1500 years of deposition the annual layering probably resulted from highly seasonal rainfall comparison of the uppermost layers of the speleothem with meteorological records shows that precipitation of caco3 in drotsky s cave was controlled by climate thickness of calcite layers correlates with rainfall suggesting that calcite precipitation was largely dependent on the quantity of water supplied to the speleothem by contrast thickness of aragonite layers correlates with temperature although variation in temperature cannot explain greater aragonite abundance on the sides of the speleothem compared to its center mg ca ratios in calcite layers increase upward to the bases of overlying aragonite layers and analyses of cave waters suggest that fluid mg ca ratios reach levels sufficient to cause aragonite precipitation increasing evaporation which caused greater ionic strength and supersaturation resultant increasing mg ca ratios in the fluid and perhaps increasing temperature probably combined to cause aragonite precipitation detailed petrographic analysis suggests that each annual cycle of caco3 precipitation began with relatively intense fluid flow sometimes sufficient to dissolve some of the underlying aragonite before precipitation of calcite calcite precipitation under a thick fluid layer allowed euhedral crystals to form at first but thinning of the fluid to a film allowed only flatly terminated calcite crystals by season s end as fluid flow diminished increasing evaporation increasing mg ca ratios in the fluid and perhaps increasing temperature combined to cause aragonite precipitation to begin particularly on the sides of the speleothem in some years fluid flow diminished to the point that dust accumulated on aragonite surfaces before the onset of the next year s precipitation p

occurrence of hypogenic caves in a karst region examples from central italy the caves of the umbria and marche regions in central italy are made up of three dimensional maze systems that display different general morphologies due to the various geological and structural contexts at the same time the internal morphologies of the passages galleries and shafts present some similarity with solutional galleries characterized by cupolas and blind pits anastamotic passages roof pendants and phreatic passages situated at different levels some of these caves are still active as is the case for frassassi gorge parrano gorge and acquasanta terme with galleries that reach the phreatic zone where there is a rising of highly mineralized water rich in hydrosulfydric acid and with erosion of limestone walls and the formation of gypsum elsewhere there are fossil caves such as monte cucco and pozzi della piana where large speleothems of gypsum are present 500 m or more above the regional water table in all of these important karst systems it is possible to recognize basal input points through fracture and intergranular porosity networks at the base of the oxidizing zone in the core of the anticline where mineralized water rises up from the triassic evaporitic layers in small hydrogeological circuits different underground morphologies can derive from the presence of a water table related to an external stream or from the confined setting of the carbonate rocks underlying low permeable sedimentary cover where artesian conditions can occur

sulphuric acid geofluid contribution on thermal carbonate coastal springs italy hypogenic caves developed by sulphuric acid speleogenesis are known all over the world among which the santa cesarea terme caves have been included they are four submerged caves located along a coastal carbonate sector in southern italy and hosting the outflow of coastal springs of thermal mixed waters from 21 to 33 c these waters derive from the mixing of three water end members the fresh pure groundwater of a wide karstic aquifer the deep sulphur thermal water and the seawater this cave system represents an almost unique case of hypogenic sea caves in carbonate environment the thermal mixed waters have a different effect on the surrounding rocks of the caves influencing the sulphuric acid speleogenetic process within the whole cave system to understand the complex and overlapping natural processes acting on the development of these coastal caves a multidisciplinary study has been carried out this study has integrated all the data resulting from different methods and technologies merging morphology structural geology hydrogeology hydrogeochemistry and mineralogy this multidisciplinary study has allowed to define the main geochemical processes acting within these caves including the cave development and the formation of the mineral concretions after the introduction of h2s in the thermal waters formed by the reduction of sulphates in the sedimentary deposits crossed at depth in the offshore the oxidation occurs within the caves producing sulphuric acid favoured by upwelling deep seated thermal flows this acid dissolves the limestone with condensation corrosion process that involve replacement of limestone rock with gypsum this process has resulted to be more active and remarkable within the gattulla cave one of the santa cesarea terme sea caves

effect of aragonite to calcite transformation on the geochemistry and dating accuracy of speleothems an example from castanar cave spain aragonite speleothems are increasingly being used as high resolution climate proxies however aragonite is unstable and susceptible to diagenetic transformation into calcite leading to mineralogical textural and geochemical alterations that have not been fully investigated to provide some insights to these modifications this study combines stable isotope geochemistry and u series dating with petrological observations and empa elemental analyses to characterize a stalagmite from castanar cave caceres spain that shows primary aragonite diagenetically altered and with reverse ages the diagenetic processes include recrystallization to calcite micritization and dissolution characterization and interpretation of the chemistry and nature of the waters from which the aragonite precipitated and of the ones that subsequently formed the calcite indicates that both polymorphs formed from the same fluids these fluids hydrochemically evolved from an aragonite mode to a calcite mode along a diagenetic path within the sample the results show that during transformation the system stayed close in one of the stages and open in the other with the same textural result reverse ages are found either in the recrystallized areas or in the primary aragonite caused by two different u remobilization mechanisms u leaching due to flowing waters on the surface and u loss during the transformation process these results highlight the complex behavior of speleothems during diagenesis and the impact on the geochemical information of the primary and secondary phases and thus the importance of petrological and geochemical characterization of speleothems for paleoclimatic studies

improving the analysis of biogeochemical patterns associated with internal waves in the strait of gibraltar using remote sensing images abstract high amplitude internal waves haiws are physical processes observed in the strait of gibraltar the narrow channel between the atlantic ocean and the mediterranean sea these internal waves are generated over the camarinal sill western side of the strait during the tidal outflow toward the atlantic ocean when critical hydraulic conditions are established haiws remain over the sill for up to 4 h until the outflow slackens being then released mostly towards the mediterranean sea these have been previously observed using synthetic aperture radar sar which captures variations in surface water roughness however in this work we use high resolution optical remote sensing with the aim of examining the influence of haiws on biogeochemical processes we used hyperspectral images from the hyperspectral imager for the coastal ocean hico and high spatial resolution 10 m images from the multispectral instrument msi onboard the sentinel 2a satellite this work represents the first attempt to examine the relation between internal wave generation and the water constituents of the camarinal sill using hyperspectral and high spatial resolution remote sensing images this enhanced spatial and spectral resolution revealed the detailed biogeochemical patterns associated with the internal waves and suggests local enhancements of productivity associated with internal waves trains

comparison of aquifer characterization approaches through steady state groundwater model validation a controlled laboratory sandbox study 1 groundwater modeling has become a vital component to water supply and contaminant transport investigations an important component of groundwater modeling under steady state conditions is selecting a representative hydraulic conductivity k estimate or set of estimates which defines the k field of the studied region currently there are a number of characterization approaches to obtain k at various scales and in varying degrees of detail but there is a paucity of information in terms of which characterization approach best predicts flow through aquifers or drawdowns caused by some drawdown inducing events the main objective of this paper is to assess k estimates obtained by various approaches by predicting drawdowns from independent cross hole pumping tests and total flow rates through a synthetic heterogeneous aquifer from flow through tests specifically we 1 characterize a synthetic heterogeneous aquifer built in the sandbox through various techniques permeameter analyses of core samples single hole cross hole and flow through testing 2 obtain mean k fields through traditional analysis of test data by treating the medium to be homogeneous 3 obtain heterogeneous k fields through kriging and steady state hydraulic tomography and 4 conduct forward simulations of 16 independent pumping tests and six flow through tests using these homogeneous and heterogeneous k fields and comparing them to actual data results show that the mean k and heterogeneous k fields estimated through kriging of small scale k data core and single hole tests yield biased predictions of drawdowns and flow rates in this synthetic heterogeneous aquifer in contrast the heterogeneous k distribution or k tomogram estimated via steady state hydraulic tomography yields excellent predictions of drawdowns of pumping tests not used in the construction of the tomogram and very good estimates of total flow rates from the flow through tests these results suggest that steady state groundwater model validation is possible in this laboratory sandbox aquifer if the heterogeneous k distribution and forcing functions boundary conditions and source sink terms are characterized sufficiently

multimodal internal waves generated over a subcritical ridge impact of the upper ocean stratification abstractinteraction of barotropic tides with subsurface topography is vital to ocean mixing yet the behavior of large amplitude nonlinear internal solitary waves isws that can cause strong mixing remains poorly understood especially that of higher mode and multimodal internal waves therefore a 2 5 dimensional nonhydrostatic model with adjustable vertical resolution was developed to investigate effects of upper ocean stratification on tidally induced multimodal internal waves and to show how they are generated by the subcritical ridge where only upward propagating internal wave beams iwbs are present the effects of the stratification on properties and characteristics of the excited iwbs and on the energy partition of the radiated mode 1 and mode 2 internal waves were investigated based on the model results higher modes of internal waves can also be effectively generated in the iwbs by the subcritical topography and the contribution to iwbs from higher modes increases with the upper ocean stra

the boiling water phenomena at camarinal sill the strait of gibraltar abstract a detailed description of high amplitude steady topographic internal waves recorded at camarinal sill during a survey on the r v investigador is presented these internal waves are generated during the maximum outflow westward stage of the tidal current and remain over the sill for more than 4 h until the outflow slackens then being released towards the mediterranean their amplitudes are comparable to the well known internal bore of camarinal sill occurring during maximum outflow during spring tides however they respond to a different physical origin and their spatial features are also quite different in fact the favourable hydraulic conditions for the generation of steady waves over the sill inhibit the internal bore generation and vice versa analysis of the observations suggests that steady internal waves are the result of a resonant response of the stratified fluid over the sill to the forcing of the flow on the across sill topography an important consequence of the steady internal waves with clear biological implications is the significant mixing phenomena that are induced mixing is enabled by an enhancement of the shear at the trough together with a significant induced vertical advection

cross formational rising groundwater at an artesian karstic basin the ayalon saline anomaly israel it is proposed that a geothermal artesian karstic system at the central part of the yarkon taninim aquifer creates the ayalon saline anomaly asa whose mechanism has been under debate for several decades a 4 year long detailed groundwater monitoring was carried out at 68 new shallow boreholes in the ayalon region accompanied by a comprehensive survey of karstic voids results indicate the rising of warm brackish groundwater through highly permeable swarms of karstic shafts serving as an outflow of the artesian geothermal system the asa area contains hot spots where groundwater contrasts with normal water hundreds of meters away the asa temperature reaches 30 8 c w5 8c warmer than its surroundings chloride concentration reaches 528 mg l 50 100 mg l in the surrounding h2s concentration reaches 5 6 mg l zero all around and ph value is 7 0 compared with 7 8 around subsequently the hydrothermal water flows laterally of at the watertable horizon through horizontal conduits mixing with normal fresh water which had circulated at shallow depth following rainy seasons maximal watertable rise is observed in the asa compared to its surroundings regional hydrogeology considerations suggest that the replenishment area for the asa water is at the samaria mountains east of the asa the water circulates to a great depth while flowing westward and a cross formational upward flow is then favored close the upper sub aquifer s confinement border

a study of internal wave propagation in the strait of gibraltar using shore based marine radar images abstract an x band marine radar on windmill hill gibraltar was used to monitor the propagation of internal waves in the strait of gibraltar during march april and june 1986 surface roughness features of the waves were observed out to a range of 15 km from photographic images of the radar screen the positions of image features were measured manually using a digitizing table and these data were then computer processed to give wave arrival times and phase speeds during most tidal cycles an internal undular bore generated at camarinal sill was observed to pass eastward a waves these occurred throughout the experiments although less frequently near neap tides the time of travel to gibraltar varied significantly so that the bore arrived between four and nine hours after high water arrival times were found to be closely related to the amplitude of the upper layer tidal current this current had a strong diurnal component which was manifested as an inequality between the arrival times of success

tide at the eastern section of the strait of gibraltar from october 1995 to april 1996 three mooring lines were deployed at the eastern entrance of the strait of gibraltar the spatial coverage of the mooring array allows for a good description of the tides they exhibit a dominant semidiurnal nature and a noticeable baroclinic structure that matches the one of the mean exchange tidal currents in the upper layer are irregular and usually too weak to reverse the mean upper layer flow that keeps on flowing east lower layer flow reverses with semidiurnal periodicity because of the smallness of the mean flow and the appreciable amplitude of the regular semidiurnal oscillation of tidal currents in this layer tidal transports can be satisfactorily compared with previous estimates of bryden et al 1994 if we allow for strong internal divergences associated with the internal tide no significant eddy flux of water transport tidal rectification is observed at the eastern section contrary to the almost 50 of the total layer transport found by bryden et al 1994 in camarinal sill section time dependent hydraulic theory provides a good scenario for interpreting these two independent sets of observations despite the fact that the composite froude number does not reach the critical values predicted in the hydraulic models most of the time

interpretation of ancient epikarst features in carbonate successions a note of caution abstract in shallow marine carbonate successions of the phanerozoic evidence for shorter lived subaerial exposure stages of ancient carbonate seafloors is commonly found in the presence of small scale epi karst solution pits in discontinuity surfaces under favorable conditions these solution features are accompanied by soil features including calcretes or root traces alveolar septal structures petrographic evidence such as pendant cements circumgranular cracks or pisoliths bleaching and staining of carbonate rocks or circumstantial geochemical evidence perhaps more often however ancient carbonate successions lack undisputable evidence for meteoric karsting using a well exposed case example from the aptian of oman we here document that the superficial visual field inspection of solution pits in discontinuity surfaces may lead to erroneous interpretations outcrops at jabal madar a diapiric structure allow for an in depth analysis of dissolution features in the regionally extensive top shu aiba discontinuity the solution pits discussed here were investigated for their stratigraphic position their orientation relative to bedding planes diagenetic and petrographic features and their potential relation to extensional fractures related to the updoming of jabal madar the main message brought forward is that under burial conditions spatially localized hypogenic carbonate leaching may form features that are easily mistaken for ancient meteoric epikarst these features preferentially form in interstratal positions where fractured massive carbonate rocks are capped by a major discontinuity surface overlain by non fractured argillaceous sediments thus while dissolution reprecipitation processes in the burial phreatic realm are omni directional in permeable carbonates low permeability argillaceous fines are not or to a much lesser extent prone to chemical corrosion as a consequence carbonate aggressive burial fluids leach out pits at the carbonate shale interface these appear to protrude perpendicular as bowl shaped depressions into the underlying limestones and are in the case examples documented here preferentially aligned along factures these findings have significance for the interpretation of ancient epikarst features in shallow marine carbonate successions

vertical structure of tidal currents over the camarinal sill at the strait of gibraltar an acoustic doppler current profiler adcp is used to estimate the vertical structure of currents at the camarinal sill at the strait of gibraltar the most important tidal components namely m2 s2 o1 k1 m4 m3 msf and mm are examined the semidiurnal tides are the most energetic with along strait speeds of up to 120 cm s 1 for m2 and 48 cm s 1 for s2 the diurnal tides have along strait speeds of 15 35 cm s 1 m4 increases from 4 cm s 1 in the upper layer to 15 cm s 1 below 220 m the fortnightly component msf reaches speeds in excess of 30 cm s 1 at the upper 120 m the vertical structure of the tidal signal is complicated differs between semidiurnal and diurnal tides and varies between spring and neap tides plausible assumptions about the density profile and the bottom friction yield tidal components similar to those observed the effects of friction are described by the use of an analytical constant eddy viscosity model and the effects of stratification by estimating the internal modes at each tidal frequency the major part of the tidal signal is barotropic with the internal tide modes and the frictional effects contributing 20 cm s 1 for the semidiurnal tides nevertheless individual modes reach 50 cm s 1 the internal tides for the diurnal components are 5 cm s 1 with individual modes reaching 8 cm s 1 the vertical profile of msf can be explained by the use of internal modes reaching amplitudes of 40 cm s 1 the fitting of the internal wave modes to the vertical profiles also explains the observed phase change with depth of the semimajor axis the comparison with pressure difference across the strait is consistent with previous studies this report is the first on the adcp time series on the camarinal sill

emine bair khosar cave in the crimea a huge bone accumulation of late pleistocene fauna abstract the crimean mountains are well known from the abundance of middle and late palaeolithic sites and palaeontological remains recovered from cultural layers in caves and rockshelters the fossil bearing deposits of emine bair khosar cave located at the elevation of 1000 m on the chatyrdag plateau yielded a very diverse and numerous vertebrate remains that widen the knowledge of late pleistocene faunal diversity in the crimea the assemblage comprised in total almost 50 species of vertebrates studies included geomorphological geological and stratigraphic analyses as well ams 14c dating faunal remains were present in ten palaeontological sites the main bone accumulation section ba2 was deposited during middle valdai or vytachiv mis 3 interstadial and including a long time gap to the end of the pleistocene and the holocene comparison of the emine bair khosar fauna with vertebrate faunas of other crimean sites showed a remarkable stability in the faunal composition and frequency during the whole mis 3 interstadial steppe and other open country species dominated in the compared assemblages while boreal tundra species were far less numerous inhabitants of forests including red deer and some rodents were stable members of fossil assemblages

stable isotope data as constraints on models for the origin of coralloid and massive speleothems the interplay of substrate water supply degassing and evaporation abstract many speleothems can be assigned to one of two morphological groups massive speleothems which consist of compact bulks of material and coralloids which are domal to digitate in form faster growth on protrusions of the substrate occurs in the typical growth layers of coralloids where those layers are termed coralloid accretions but it is not observed in the typical layers of massive speleothems which in contrast tend to smoothen the speleothem surface and can therefore be defined as smoothing accretions the different growth rates on different areas of the substrate are explainable by various mechanisms of caco3 deposition e g differential aerosol deposition differential co2 and or h2o loss from a capillary film of solution deposition in subaqueous environments to identify the causes of formation of coralloids rather than massive speleothems this article provides data about 13c and 18o at coeval points of both smoothing and coralloid accretions examining the relationship between isotopic composition and the substrate morphology in subaerial speleothems data show enrichment in heavy isotopes both along the direction of water flow and toward the protrusions the first effect is due to h2o evaporation and co2 degassing during a gravity driven flow of water gravity stage and is observed in smoothing accretions the second effect is due to evaporation and degassing during water movement by capillary action from recesses to prominences capillary stage and is observed in subaerial coralloids both effects coexist in smoothing accretions interspersed among coralloid ones intermediate stage thus this study supports the origin of subaerial coralloids from dominantly capillary water and disproves their origin by deposition of aerosol from the cave air on the other hand subaqueous coralloids seem to form by a differential mass transfer from a still bulk of water toward different zones of the substrate along diffusion flux vectors of nutrients perpendicular to the iso depleted surfaces finally this isotopic method has proved useful to investigate the controls on speleothem morphology and to obtain additional insights on the evolution of aqueous solutions inside caves

morphogenesis of hypogenic caves abstract hypogenic speleogenesis is the formation of solution enlarged permeability structures by waters ascending to a cave forming zone from below in leaky confined conditions where deeper groundwaters in regional or intermediate flow systems interact with shallower and more local groundwater flow systems this is in contrast to more familiar epigenic speleogenesis which is dominated by shallow groundwater systems receiving recharge from the overlying or immediately adjacent surface hypogenic caves are identified in various geological and tectonic settings formed by different dissolutional mechanisms operating in various lithologies despite these variations resultant caves demonstrate a remarkable similarity in patterns and meso morphology which strongly suggests that the hydrogeologic settings were broadly identical in their formation hypogenic caves commonly demonstrate a characteristic suite of cave morphologies resulting from rising flow across the cave forming zone with distinct buoyancy dissolution components in addition to hydrogeological criteria hydrostratigraphic position recharge discharge configuration and flow pattern viewed from the perspective of the evolution of a regional groundwater flow system morphogenetic analysis is the primary tool in identifying hypogenic caves cave patterns resulting from ascending transverse speleogenesis are strongly guided by the permeability structure in a cave formation they are also influenced by the discordance of permeability structure in the adjacent beds and by the overall hydrostratigraphic arrangement three dimensional mazes with multiple storeys or complex 3 d cave systems are most common although single isolated chambers passages or crude clusters of a few intersecting passages may occur where fracturing is scarce and laterally discontinuous large rising shafts and collapse sinkholes over large voids associated with deep hydrothermal systems are also known hypogenic caves include many of the largest by integrated length and by volume documented caves in the world more importantly hypogenic speleogenesis is much more widespread than it was previously presumed growing recognition of hypogenic speleogenesis and improved understanding of its peculiar characteristics has an immense importance to both karst science and applied fields as it promises to answer many questions about karst porosity especially as deep seated settings are concerned which remained poorly addressed within the traditional epigenetic karst paradigm

frequency dependent hydraulic properties estimated from oscillatory pumping tests in an unconfined aquifer summary oscillatory pumping tests were conducted at the boise hydrogeophysical research site a periodic pressure signal is generated by pumping and injecting water into the aquifer consecutively and the pressure response is recorded at many points around the source we present and analyze the data from the field test after applying fourier analysis we then match the data with a recently derived analytical solution for homogeneous formations to estimate the equivalent aquifer properties conductivity k specific storage s s and specific yield s y the estimated values are shown to be in agreement with previous estimates conducted at this site we observe variations in the estimated parameters with different oscillation periods of pumping the trend of the parameters with changing period is discussed and compared to predictions by existing theory and laboratory experiments dealing with dynamic effective properties it is shown that the results are qualitatively consistent with recent works on effective properties of formations of spatially variable properties in oscillatory flow to grasp the impact of heterogeneity a simple configuration is proposed helping explain the observed increase in effective conductivity with decreasing period

self potential signals induced by periodic pumping tests 1 we measured the variations of the self potential sp during periodic pumping tests performed at a test site located near a freshwater reservoir kemnader see bochum germany successions of injection and production intervals were applied in a borehole penetrating a jointed sandstone aquifer we report the sp observations for tests with periods ranging between 10 and 60 min and flow rates between 10 and 25 l min 1 the sp responses at the surface exhibit the imposed period but are not truly harmonic contrary to the hydraulic pressure and sp measured in monitoring wells in the grassy zone around the injection well the amplitude of the sp signals decreases with distance from the injection well around one order of magnitude at 10 m in rough agreement with predictions for radial flow in a homogeneous medium around an infinite source the shape of the sp responses also evolves with distance fourier spectral analysis reveals that the surface signals generally contain two main components at the main period and at half the period with the relative weight of the subperiodic components increasing with distance furthermore the characteristics of the sp responses depend on whether the boreholes are left open or closed by packers the comparison between surface and borehole measurements suggests that nonlinear phenomena are acting probably related to the saturation and desaturation processes occurring in the vadose zone

time spatial variability observed in velocity of propagation of the internal bore in the strait of gibraltar 1 some aspects of the time spatial variability of the phase speed of the internal bore generated almost every tidal cycle in camarinal sill are revised using a set of high resolution experimental data collected in two different positions of the strait during may 2003 this variability is mainly driven by the intense tidal currents comparable with the intrinsic propagation velocity of the first mode baroclinic bore it is shown that the importance of the diurnal tide in the strait of gibraltar induces a considerable diurnal inequality on the bore velocity with an observed maximum difference of 0 7 ms 1 between the speed of two consecutives bores propagating along the eastern part of the strait a regularly spatial pattern has been also found the internal bore reaches its maximum velocity in tarifa narrows a theoretical estimation predicts an extreme phase speed of 2 6 ms 1 during our period of study

characteristics and formation mechanisms of the unconformity related paleokarst reservoirs in the upper sinian northwestern tarim basin china abstract in the late sinian the tarim basin experienced regional tectonic uplift and subaerial exposure a regional unconformity was extensively distributed during the succession from the sinian to cambrian as a result a large number of secondary pores were developed in the upper sinian qegebulake formation an integrated study based on petrographical and petrophysical analysis geochemistry karstology and fluid inclusions was performed to provide insight into the characteristics and formation mechanism of the upper sinian carbonate reservoirs the reservoir rocks mainly include microbial dolomite crystalline dolomite and breccias reservoir matrix porosity and permeability range from 0 30 to 11 06 and from 0 00156 md to 1 49 md respectively geological and geochemical characteristics suggest that three phases of dissolution were determined to be responsible for the development of the reservoirs within about 70 m beneath the unconformity they are meteoric dissolution during subaerial exposure and deep seated hydrothermal dissolution and organic acid dissolution during the burial stage the upper sinian dolomite underwent strong meteoric dissolution which is supported by the appearance of the unconformity and the associated caves the geochemical characteristics of the cave filling calcite further indicate the diagenetic overprint from meteoric water including the relatively negative values of 18o 18 46 to 8 5 vpdb and wide range of 13c 8 11 to 0 24 vpdb low ree 1 77 4 23 ppm and yb la and yb ca variation the occurrence of saddle dolomite as well as analytical results such as 13c 0 67 2 52 vpdb and 18o 13 21 to 9 81 vpdb isotope signature and high homogenization temperature of fluid inclusions in quartz 87 2 to 220 c and saddle dolomite 82 3 135 4 c suggest that the reservoirs rocks experienced interaction with hydrothermal fluids only bitumen occurred in the edge of secondary pores formed by dissolution of quartz and saddle dolomite which suggests that organic acid dissolution likely occurred during the evolution of reservoirs a geological model for the evolution of the paleokarst reservoirs is proposed through the analysis of major reservoir controlling factors the primary pore types and reservoir petrophysical property of the qigebulake formation mainly depend on the sedimentation supergene karstification is the most important process for reservoir formation deep seated hydrothermal activity has both positive and negative attribution on the formation of reservoirs organic acid dissolution plays an active role in the formation and preservation of reservoirs this study provides a useful reference for hydrocarbon exploration in the deep buried sinian carbonate reservoirs

measuring well hydraulic connectivity in fractured bedrock using periodic slug tests summary periodic hydraulic experiments were conducted in a five spot well cluster completed in a single bedding plane fracture tests were performed by using a winch operated slug submerged solid cylinder to create a periodic head disturbance in one well and observing the phase shift and attenuation of the head response in the remaining wells transmissivity t and storativity s were inverted independently from head response inverted t decreased and s increased with oscillation period estimated s was more variable among well pairs than t suggesting s may be a better estimator of hydraulic connectivity among closely spaced wells these estimates highlighted a zone of poor hydraulic connection that was not identified by a constant rate test conducted in the same wells periodic slug tests appear to be a practical and effective technique for establishing local scale spatial variability in hydraulic parameters

morphometry and distribution of isolated caves as a guide for phreatic and confined paleohydrological conditions isolated caves are a special cave type common in most karst terrains formed by prolonged slow water flow where aggressivity is locally boosted the morphometry and distribution of isolated caves are used here to reconstruct the paleohydrology of a karstic mountain range within a homogenous karstic rock sequence two main types of isolated caves are distinguished and each is associated with a special hydrogeologic setting maze caves form by rising water in the confined zone of the aquifer under the mt scopus group israel confinement while chamber caves are formed in phreatic conditions apparently by lateral flow mixing with a vadose input from above

relationships between colour and diagenesis in the aragonite calcite speleothems in basajaun etxea cave spain abstract basajaun etxea cave north spain contains a wide morphological and colour variety of speleothems most of them are composed of aragonite but calcite speleothems are also found their most common colour is white but there are also pink green and turquoise speleothems in different areas of the cave mg rich dissolution waters from the cave s crystalline dolostone and magnesite host rock favour aragonite precipitation and drive important diagenetic changes in this paper we will discuss how diagenesis modifies speleothem texture mineralogy and geochemistry causing significant changes in the colour we also discuss how speleothems that have undergone diagenesis may also be useful indictors of paleoclimatic conditions our work shows that diagenesis changes the colour of the speleothems because of the mobility of the chromophore elements during this process along with this elemental alteration comes the loss of the primary isotopic signals of speleothems detailed petrological studies of speleothems should precede their analysis for palaeoclimatic reconstruction so that influence of areas affected by diagenesis can be eliminated in addition diagenetic signals also contain valuable information on the changes of the waters within the cave and the overall evolution of speleothems and the cave itself

three dimensional imaging of aquifer and aquitard heterogeneity via transient hydraulic tomography at a highly heterogeneous field site abstract previous studies have shown that geostatistics based transient hydraulic tomography tht is robust for subsurface heterogeneity characterization through the joint inverse modeling of multiple pumping tests however the hydraulic conductivity k and specific storage ss estimates can be smooth or even erroneous for areas where pumping observation densities are low this renders the imaging of interlayer and intralayer heterogeneity of highly contrasting materials including their unit boundaries difficult in this study we further test the performance of tht by utilizing existing and newly collected pumping test data of longer durations that showed drawdown responses in both aquifer and aquitard units at a field site underlain by a highly heterogeneous glaciofluvial deposit the robust performance of the tht is highlighted through the comparison of different degrees of model parameterization including 1 the effective parameter approach 2 the geological zonation approach relying on borehole logs and 3 the geostatistical inversion approach considering different prior information with without geological data results reveal that the simultaneous analysis of eight pumping tests with the geostatistical inverse model yields the best results in terms of model calibration and validation we also find that the joint interpretation of long term drawdown data from aquifer and aquitard units is necessary in mapping their full heterogeneous patterns including intralayer variabilities moreover as geological data are included as prior information in the geostatistics based tht analysis the estimated k values increasingly reflect the vertical distribution patterns of permeameter estimated k in both aquifer and aquitard units finally the comparison of various tht approaches reveals that differences in the estimated k and ss tomograms result in significantly different transient drawdown predictions at observation ports

speleodisc a 3 d quantitative approach to define the structural control of endokarst an application to deep cave systems from the picos de europa spain abstract the influence of geological structure on endokarst can be studied by establishing the relationships between discontinuities faults joints and bedding with a cave survey the cave survey elaborated by speleologists represents the directions and inclinations of the cave conduits and can be compared to the strike and dip of the discontinuities of a karst massif this paper proposes a methodology the speleodisc method which is effective in defining the structural control of the endokarst the method has been designed and applied in a pilot area from the alpine karst massif of the picos de europa where long and deep cave systems are well developed including more than 360 km of conduits in its entirety the method is based on the projection of cave surveys on geological maps and cross sections and the comparison between the direction and inclination of the cave survey data and the geometry of the massif discontinuities in three spatial dimensions 3 d the speleodisc method includes 1 collection and management of topographic information 2 collection and management of cave data 3 definition of the groups of conduits 4 elaboration of geological maps and cross sections 5 collection of discontinuity data bedding faults and joints 6 definition of groups of discontinuities and 7 comparison between the cave conduit groups and the families of discontinuities the speleodisc method allows us define the influence of the major and minor structures on the caves geometry estimating percentage of caves forced by each group of massif discontinuities and their intersections in 3 d nevertheless the speleodisc approach is mainly controlled by 1 the amount and quality of the cave survey data and 2 the abundance of cave deposits covering the conduit which can mask the original geometry

a travel time based hydraulic tomographic approach 1 hydraulic tomography is a method to identify the three dimensional spatial distribution of hydraulic properties in the subsurface we propose a tomographic approach providing the inversion of travel times of hydraulic or pneumatic tests conducted in a tomographic array the inversion is based on the relation between the peak time of a recorded transient pressure curve and the diffusivity of the investigated system the development of a transformation factor enables the inversion of further travel times besides the peak time of a transient curve as the early travel times of the curve are mainly related to preferential flow features while the inversion based on late travel times are reflecting an integral behavior it can be assumed that the different inversion results reflect the properties of the overall system by comparing the different reconstructions the system interpretation therefore becomes more comprehensive and reliable furthermore the similarity of the proposed hydraulic tomographic approach to seismic travel time tomography allows us to apply the inversion algorithms which are used for seismic tomography we therefore apply the method of staggered grids which enables to refine the grid resulting in a higher nominal resolution to data from a set of interference tests arranged in a tomographic array the tests were conducted in an unsaturated fractured sandstone cylinder in the laboratory the three dimensional reconstructions of the diffusivity distribution are found to be highly reliable and robust in particular the mapped fracture of the sandstone cylinder coincides with our reconstructed diffusivity distribution

three dimensional interference test interpretation in a fractured aquifer using the pilot point inverse method a geostatistical conditional simulation routine that employs both parametric and nonparametric geostatistics is coupled to the pilot point inverse method to simulate the spatial distribution of conductivities in a dolomitic aquifer which is fractured in some areas and unfractured in others an inversion is then conducted to obtain the conductivities within the fractured and nonfractured parts of the aquifer to match interference data from a series of three dimensional pumping tests for an ensemble of 100 conditional simulations the calibrated and predicted drawdowns match the observed drawdowns well a comparison to the transmissivity interpreted from a single well pumping test compared very well to the geometric mean transmissivity calculated from the calibrated realizations in this study the results from this study indicate that conditioning the conductivity fields to the geologic facies data in this case fractured unfractured categorical data as well as to ample transient hydraulic data can lead to robust groundwater flow models which can adequately predict the response to other hydraulic interference tests

high sulfate concentrations in limestone springs an important factor in conduit initiation major ion concentrations in 404 springs in carbonate strata were found to exhibit a wide range in sulfate values sulfate concentrations are often much larger than would be expected from the analysis of samples from surface outcrops springs in the sierra madre oriental mexico the rocky mountains front range canada and the peak district england show similarities in sulfate concentration and in spatial distribution springs with high sulfate concentrations are found close to base level and are thermal springs with low sulfate concentration are found at higher elevations above base level and are not thermal there is a direct relationship between sulfate concentration and spring temperature and an inverse relationship with discharge the results from the three areas described support a model of local and regional flow patterns with deep regional flow providing the warm sulfate rich water the initial fracture porosity development in these aquifers may owe as much to the removal of sulfur minerals as to the removal of carbonate minerals high sulfate values are frequently found in carbonate aquifers so this model may be of widespread applicability

on the importance of geological data for hydraulic tomography analysis laboratory sandbox study abstract this paper investigates the importance of geological data in hydraulic tomography ht through sandbox experiments in particular four groundwater models with homogeneous geological units constructed with borehole data of varying accuracy are jointly calibrated with multiple pumping test data of two different pumping and observation densities the results are compared to those from a geostatistical inverse model model calibration and validation performances are quantitatively assessed using drawdown scatterplots we find that accurate and inaccurate geological models can be well calibrated despite the estimated k values for the poor geological models being quite different from the actual values model validation results reveal that inaccurate geological models yield poor drawdown predictions but using more calibration data improves its predictive capability moreover model comparisons among a highly parameterized geostatistical and layer based geological models show that 1 as the number of pumping tests and monitoring locations are reduced the performance gap between the approaches decreases and 2 a simplified geological model with a fewer number of layers is more reliable than the one based on the wrong description of stratigraphy finally using a geological model as prior information in geostatistical inverse models results in the preservation of geological features especially in areas where drawdown data are not available overall our sandbox results emphasize the importance of incorporating geological data in ht surveys when data from pumping tests is sparse these findings have important implications for field applications of ht where well distances are large

study of the generation and propagation of internal waves in the strait of gibraltar using a numerical model and synthetic aperture radar images of the european ers 1 satellite a weakly nonhydrostatic two layer numerical model based on the boussinesq equations is presented which is capable of describing among others the generation and propagation of nonlinear weakly dispersive internal waves in the strait of gibraltar the model depends on one space coordinate only but it retains several features of a fully three dimensional model by including a realistic bottom profile a variable channel width and a trapezoidal channel cross section the nonlinear primitive boussinesq equations include horizontal diffusion bottom friction and friction between the two water layers the model is driven by a height difference of the mean interface depth between the atlantic and the mediterranean boundaries and by semidiurnal tidal oscillations of the barotropic transport the model presented in this paper describes 1 the mean and tidal flow in the strait of gibraltar 2 the variation of the depth of the interface during a tidal cycle 3 the generation of strong depressions of the interface at the western sides of the spartel sill and the camarinal sill 4 the generation of strong eastward propagating internal bores and 5 their disintegration into trains of internal solitary waves the surface convergence patterns associated with depressions of the interface at the camarinal sill internal bores and internal solitary waves are calculated and compared with roughness patterns visible on synthetic aperture radar sar images of the first european remote sensing satellite ers 1 in total 155 ers 1 sar scenes from 94 satellite overflights over the strait of gibraltar which were acquired in the period from january 1992 to march 1995 have been analyzed it is shown that the proposed model is capable of explaining the observed temporal and spatial evolution of surface roughness patterns associated with eastward propagating internal waves inside the strait of gibraltar as well as the observed east west asymmetry of the internal wave field

the geochemistry and origin of fluids in the carbonate structure of the hranice karst with the world s deepest flooded cave of the hranicka abyss czech republic abstract the origin of fluids in the hranice karst containing the deepest flooded abyss in the world has been investigated using hydrogeological hydrogeochemical and isotopic data at least a part of the co2 gas originates in the mantle as indicated by very enriched 13c dic values and from existing he isotope analyses the origin of groundwater in the karstic aquifer which is exploited at the teplice nad becvou spa is meteoric with a recharge area about 200 m above the becva river valley as indicated by depleted values of 2h and 18o compared to the river water based on detectable tritium the groundwater is from 20 to 50 years old water in the hranicka abyss and in the zbrasov aragonite caves is a mixture of carbonate aquifer groundwater with the river and or shallow groundwater comprising variable proportions of both end members water in death cave lake seems to be affected by agriculture contaminated shallow groundwater as indicated by increased nitrate concentration inverse geochemical modeling of aquifer geochemistry suggested two scenarios 1 reaction of mg rich calcite with deep hypogenic co2 about 30 mmol l plus dissolution of trace amounts of halite and sylvite and cation exchange 2 reaction of mg depleted calcite and mg silicate talc as a source of mg together with deep co2 both scenarios were calibrated using 13c dic values and gave satisfactory results a conceptual model of the site has been developed which includes a gravity driven flow system where meteoric water which has recharged in the surrounding uplands is heated at depth and acquires large amounts of hypogenic co2 which preferentially dissolves mg carbonates along the pre existing tectonic features the miocene transgression followed by the later incision of the becva valley played an important role in groundwater circulation and the origin of fluids

hypogenic origin geologic controls and functional organization of a giant cave system in precambrian carbonates brazil abstract this study is focused on speleogenesis of the toca da boa vista tbv and toca da barriguda tbr the longest caves in south america occurring in the neoproterozoic salitre formation in the sao francisco craton ne brazil we employ a multidisciplinary approach integrating detailed speleomorphogenetic lithostratigraphic and geological structure studies in order to reveal the origin of the caves their functional organization and geologic controls on their development the caves developed in deep seated confined conditions by rising flow the overall fields of passages of tbv and tbr caves represent a speleogenetically exploited large ne sw trending fracture corridor associated with a major thrust this corridor vertically extends across the salitre formation allowing the rise of deep fluids in the overall ascending flow system the formation of the cave pattern was controlled by a system of sub parallel anticlines and troughs with nne ssw dominant orientation and by vertical and lateral heterogeneities in fracture distribution three cave stratigraphic stories reflect the actual hydrostratigraphy during the main phase of speleogenesis cavities at different stories are distinct in morphology and functioning the gross tree dimensional pattern of the system is effectively organized to conduct rising flow in deep seated confined conditions cavities in the lower story developed as recharge components to the system a laterally extensive conduit network in the middle story formed because the vertical flow from numerous recharge points has been redirected laterally along the highly conductive unit occurring below the major seal a scarcely fractured unit rift like and shaft like conduits in the upper story developed along fracture controlled outflow paths breaching the integrity of the major seal and served as outlets for the cave system the cave system represents a series of vertically organized functionally largely independent clusters of cavities developed within individual ascending flow cells lateral integration of clusters occurred due to hydrodynamic interaction between the flow cells in course of speleogenetic evolution and change of boundary conditions the main speleogenetic phase during which the gross cave pattern has been established and the caves acquired most of their volume was likely related to rise of deep fluids at about 520 ma or associated with rifting and the pangea break up in triassic cretaceous this study highlights the importance of speleogenetic studies for interpreting porosity and permeability features in carbonate reservoirs

internal waves and short scale distribution patterns of chlorophyll in the strait of gibraltar and alboran sea 1 a selection of asar images have been analyzed together with instantaneous images of surface chlorophyll recorded with meris and modis in order to study the relationship between the physical and biological processes associated with internal waves in the strait of gibraltar and alboran sea the images show peak levels of chlorophyll at the coastal edges to the north and south of the camarinal sill cs during the generation of internal waves and peak levels of chlorophyll associated with the wave fronts as they travel into the alboran sea the images have been compared with in situ data the results seem to indicate that during the generation of the internal waves a suction process takes place by which coastal waters rich in chlorophyll are drawn towards the center of the channel and then accompany the internal waves as they move towards the alboran sea

the use of electrical resistivity tomograms as a parameterization for the hydraulic characterization of a contaminated aquifer abstract hydraulic characterization of a contaminated aquifer is an important step in depollution processes because its hydraulic parameters control the choice and efficiency of the depollution protocol to be adopted the characterization presented in this article uses a 3d electrical resistivity imagery to identify the spatial heterogeneities of a contaminated aquifer under tidal influence indeed we use a 3d resistivity model as a source of information to parameterize the reconstruction of the hydraulic conductivity in 3d by inverting a set of hydraulic data acquired on the 13 monitored wells in response to two pumping tests this parameterization relies on the identification of the main electro facies in the resistivity model in the saturated zone which will then be exploited in the hydraulic characterization to find their corresponding hydraulic conductivity values this strategy of parameterization permits to reduce the number of the hydraulic conductivity parameters to be identified to eight hydro facies with a stochastic algorithm called the adaptive metropolis algorithm the hydraulic responses associated with the pumping tests are obtained once the natural effect of the tide is removed the hydraulic conductivity model has permitted to highlight the main heterogeneities in the aquifer in which the hydraulic conductivity is ranging between 10 4 6 10 2 8 m s this range of variability reveals the permeable and smooth character of the aquifer in which the presence of coarse sand and flint blocks enhances its transmissivity these permeable zones are electrically identified by resistive anomalies in the 3d electrical resistivity imaging

analysis of short period internal waves using wave induced surface displacement a three dimensional model approach in algeciras bay and the strait of gibraltar 1 a three dimensional nonlinear high resolution sigma coordinate hydrodynamic model was applied to study the sea surface manifestation of short period internal waves measured in algeciras bay and the strait of gibraltar model results reproduce the tidally induced generation of the internal bore over the camarinal sill and its disintegration into wave trains as it moves eastward while propagating along the strait of gibraltar toward the mediterranean sea the wave trains partly penetrate into algeciras bay with typical oscillation periods of 20 and 40 min the modeled wave induced surface train structures are compared with satellite images and in situ observational data obtained from two pressure sensors located inside the bay results demonstrate that wave induced sea surface displacements are indicators of the presence of internal waves and may be used in the context of the internal wave analysis when surface oscillations are captured with sufficient precision

morphological and speleothemic development in brujas cave southern andean range argentine palaeoenvironmental significance abstract brujas cave in the southern andean range is a well known endokarstic site in argentina however the origin and evolution of this cave system are poorly known based on morphological cave features as well as characteristics of cave deposits we propose a meteogene drawdown cave genesis including a change from phreatic to vadose conditions related to the high rate of fluvial downcutting in the area during the vadose period various cave related deposits including authogenic calcite and gypsum speleothems allogenic volcanic ash and external tufas were deposited gypsum crusts are the oldest cave deposits identified 90 2 64 3 ky bp their origin deduced from isotopic characteristics 34 s 9 6 is related to the oxidation of pyrite contained in the jurassic limestone bedrock as well as the dissolution of overlying jurassic triassic evaporite formations gypsum crust deposition is associated with evaporation of water flowing and seeping into the cave during arid environmental conditions calcite deposits precipitated from flowing water under equilibrium conditions represent the main speleothem growth period 67 6 34 ky bp in age their stable isotope values 13 c 3 to 5 and 18 o 9 to 11 may indicate slightly humid and warm conditions related to the regional minchin lacustrine phase and global oxygen isotope stage 3 following this stage a seismic event is evidenced by accumulations of broken stalactites seepage calcite speleothems covering cave walls were deposited under disequilibrium conditions by evaporation probably during holocene time finally another more recent gypsum deposition period represented by gypsum balls has been differentiated micromorphological as well as isotopic 34 s 5 6 data indicate that these gypsum forms are related to cyclic processes solution deposition from water seeping into the cave under arid conditions in addition intense volcanic activity in the area during holocene time is deduced from allogenic volcanic ash and lapilli located mainly at the entrance cave at present limited hydrological activity is observed in the cave and small tufa deposits at karstic discharge points are evidenced we conclude that the geomorphological evolution of brujas cave was controlled by climatic changes wet and dry stages under semiarid environmental conditions in a very active tectonic and volcanic setting during late quaternary time

environmental controls of speleothem mineralogy in a karstic dolomitic terrain soreq cave israel pleistocene speleothems of the soreq cave beth shemesh israel situated within karstic cretaceous dolomitic rocks consist of two major mineralogical types 1 monomineralic low magnesium calcite lmc 0 5 and 7 5 mol mgco 3 straw stalactites stalagmites helictites and pool deposits 2 mineralogically heterogeneous deposits in the form of conical stalactites flowstones and cave corals produced from thin flowing solution films or sprays in which lmc alternates with high magnesium calcite hmc 13 to 33 mol mgco 3 dolomite 33 50 mol mgco 3 and lmc laminations a unique feature of the type 2 is the continuous 0 50 mol range of mgco 3 sem and delta 18 o studies show that all calcites and dolomites grew by direct precipitation from local groundwater solutions lmc formation represents equilibrium precipitation from dripping water solution with mg ca 2 whereas hmc and dolomite precipitation occurred from solution films enriched in mg as the result of prior clos

the flow of atlantic water through the strait of gibraltar abstract we describe and analyze observations of the water exchange through the strait of gibraltar the primary observations were taken in april 1986 and included data from moored recording instruments at four locations in the strait together with an intensive survey by ship these measurements included extensive ctd profiling acoustic doppler current profiling numerous profiles from expendable instruments and imaging using a high frequency echo sounder the analysis focuses on the internal hydraulics of the strait and in particular the presence of hydraulic controls and their influence on the exchange our observations during april 1986 show that the maximal exchange condition in which a subcritical flow is bounded by supercritical flow at both ends of the strait did occur although with various subtleties not explicitly incorporated in our previous theoretical developments the atlantic water moving east along the surface encounters a control at tarifa narrows in the eastern part of the strait the mediterranean water passes through controls both at camarinal sill and at spartel sill further west at our westernmost mooring at spartel the outflowing mediterranean water is continuously supercritical with little tidal variability the control at camarinal sill is periodically lost due to tidal action and reappears on a reverse flow during a falling spring tide tangier basin bounded by camarinal and spartel sills acts as an internal reservoir for the outflowing mediterranean water the interface rising and falling through each tidal cycle during spring tides the tangier basin interface rises high enough to flood the control at camarinl sill and produces a reverse flow of the lower layer when control is lost at camarinal sill a travelling bore is released this bore may modify the location of the control acting on the surface layer in tarifa narrows the atlantic water enters the alboran sea as a jet which may have a well defined northern boundary where it separates from the european coast this boundary may be identified by the presence of a slick although the internal jump west of camarinal sill is almost certainly an area of intense mixing frictional effects do not appear to be dominant in the subcritical portion of the flow

late pleistocene and holocene mid latitude palaeoclimatic and palaeoenvironmental reconstruction an approach based on the isotopic record from a travertine formation in the guadix baza basin spain a comprehensive palaeoenvironmental reconstruction of the last 219 ka has been carried out by determining the isotopic signatures 18 o and 13 c in 766 samples of a thermogene travertine formation in the guadix baza tertiary basin granada se spain this travertine formation was dated from 220 to 5 ka by means of the alpha spectrometry technique initially the study of the 18 o values of the travertine formation was carried out because they are excellent indicators of the overall palaeoclimatic condition of a particular site likewise the evolution of 13 c values which can be directly related to the biomass development of the site has also been studied finally an integrated study of both isotopic records has been performed identifying a total of 12 climatic periods based on their palaeoclimatic and palaeoenvironmental conditions these periods are grouped into four climatic scenarios scenario a characterized by warm and dry periods scenario b characterized by cold and humid periods scenario c constituted by warm and humid periods and scenario d which is characterized by cold and dry periods palaeoclimatic scenarios a and b mainly characterized the palaeoclimatic evolution of the site while in northern europe the palaeoclimatic evolution is mainly characterized by scenarios c and d therefore it is suggested that the palaeoenvironmental evolution at lower latitudes on the iberian peninsula is the opposite of that identified in northern europe however the main climatic events identified at higher latitudes are also reflected in the studied area