conduit enlargement in an eogenetic karst aquifer summary most concepts of conduit development have focused on telogenetic karst aquifers where low matrix permeability focuses flow and dissolution along joints fractures and bedding planes however conduits also exist in eogenetic karst aquifers despite high matrix permeability which accounts for a significant component of flow this study investigates dissolution within a 6 km long conduit system in the eogenetic upper floridan aquifer of north central florida that begins with a continuous source of allogenic recharge at the santa fe river sink and discharges from a first magnitude spring at the santa fe river rise three sources of water to the conduit include the allogenic recharge diffuse recharge through epikarst and mineralized water upwelling from depth results of sampling and inverse modeling using phreeqc suggest that dissolution within the conduit is episodic occurring only during 30 of 16 sampling times between march 2003 and april 2007 during low flow conditions carbonate saturated water flows from the matrix to the conduit restricting contact between undersaturated allogenic water with the conduit wall when gradients reverse during high flow conditions undersaturated allogenic recharge enters the matrix during these limited periods estimates of dissolution within the conduit suggest wall retreat averages about 4 10 6 m day in agreement with upper estimates of maximum wall retreat for telogenetic karst because dissolution is episodic time averaged dissolution rates in the sink rise system results in a wall retreat rate of about 7 10 7 m day which is at the lower end of wall retreat for telogenetic karst because of the high permeability matrix conduits in eogenetic karst thus enlarge not just at the walls of fractures or pre existing conduits such as those in telogenetic karst but also may produce a friable halo surrounding the conduits that may be removed by additional mechanical processes these observations stress the importance of matrix permeability in eogenetic karst and suggest new concepts may be necessary to describe how conduits develop within these porous rocks

relationship between dike and volcanic conduit distribution in a highly eroded monogenetic volcanic field san rafael utah usa we mapped 63 conduits 2000 dike segments and 12 sills in the san rafael subvolcanic field utah united states where this pliocene magmatic system is eroded to a depth of 0 8 km and is exceptionally well exposed although the number of mapped conduits dikes and sills might represent minimums depending on the level of erosion and exposure mapped dikes are more numerous around the areally extensive sills and interact with sills and conduits in complex ways we analyze conduit distribution using kernel density methods and compare results with dike and sill distribution we find that the distribution of conduits matches the major features of dike distribution including development of clusters and distribution of outliers these statistical models are then applied to the distributions of volcanoes in several recently active volcanic fields where intrusion distributions must be inferred from very sparse data and compared with san rafael conduit distribution this comparison supports the use of statistical models in probabilistic hazard assessment for distributed volcanism specifically renewed dike intrusion and potential eruptions in active basaltic systems can be assessed probabilistically from the distribution of older volcanoes in distributed volcanic systems

eruption processes and deposit characteristics at the monogenetic mt gambier volcanic complex se australia implications for alternating magmatic and phreatomagmatic activity the 5 ka mt gambier volcanic complex in the newer volcanics province australia is an extremely complex monogenetic volcanic system that preserves at least 14 eruption points aligned along a fissure system the complex stratigraphy can be subdivided into six main facies that record alternations between magmatic and phreatomagmatic eruption styles in a random manner the facies are 1 coherent to vesicular fragmental alkali basalt effusive hawaiian spatter and lava flows 2 massive scoriaceous fine lapilli with coarse ash strombolian fallout 3 bedded scoriaceous fine lapilli tuff violent strombolian fallout 4 thin medium bedded undulating very fine lapilli in coarse ash dry phreatomagmatic surge modified fallout 5 palagonite altered cross bedded medium lapilli to fine ash wet phreatomagmatic base surges and 6 massive palagonite altered very poorly sorted tuff breccia and lapilli tuff phreato vulcanian pyroclastic flows since most deposits are lithified to quantify the grain size distributions gsds image analysis was performed the facies are distinct based on their gsds and the fine ash to coarse fine ash ratios these provide insights into the fragmentation intensities and water magma interaction efficiencies for each facies the eruption chronology indicates a random spatial and temporal sequence of occurrence of eruption styles except for a magmatic horizon of effusive activity occurring at both ends of the volcanic complex simultaneously the eruption foci are located along nw se trending lineaments indicating that the complex was fed by multiple dykes following the subsurface structures related to the tartwaup fault system possible factors causing vent migration along these dykes and changes in eruption styles include differences in magma ascent rates viscosity crystallinity degassing and magma discharge rate as well as hydrological parameters

porosity development in coastal carbonate aquifers geochemical mixing theory suggests that the mixing of seawater and calcite saturated fresh ground water can result in a solution that is undersaturated with respect to calcite previous studies of the mixing of such waters in carbonate rocks along certain coastlines have indicated that this mixing effect may be responsible for significant amounts of calcite dissolution and porosity development in this study potential rates of porosity development by calcite dissolution are assessed by combining geochemical mixing theory with the hydrodynamics of fresh water salt water mixing zones in a coupled reaction transport model results from the reaction path model phreeqe are used with a variable density ground water flow and solute transport model to simulate an idealized cross section of a coastal carbonate aquifer results of the simulations indicate that the dissolution process is sensitive to fresh water chemistry ground water velocities and sea level movement dissolution potential was evaluated at three field sites and evidence from those sites is in general agreement with the simulation results dissolution rates indicated by the model show that under the proper conditions this dissolution mechanism can produce significant increases in porosity over relatively short spans of geologic time tens of thousands of years

climate control of decadal scale increases in apparent ages of eogenetic karst spring water abstract water quantity and quality in karst aquifers may depend on decadal scale variations in recharge or withdrawal which we hypothesize could be assessed through time series measurements of apparent ages of spring water we tested this hypothesis with analyses of various age tracers 3h 3he sf6 cfc 11 cfc 12 cfc 113 and selected solute concentrations dissolved oxygen do no3 mg and so4 from 6 springs in a single spring complex ichetucknee springs in northern florida over a 16 yr period these springs fall into two groups that reflect shallow short group 1 and deep long group 2 flow paths some tracer concentrations are altered with cfc 12 and cfc 113 concentrations yielding the most robust apparent ages these tracers show a 10 20 yr monotonic increase in apparent age from 1997 to 2013 including the flood recession that followed tropical storm debby in mid 2012 this increase in age indicates most water discharged during the study period recharged the aquifer within a few years of 1973 for group 2 springs and 1980 for group 1 springs inverse correlations between apparent age and do and no3 concentrations reflect reduced redox state in older water positive correlations between apparent age and mg and so4 concentrations reflect increased water rock reactions concentrated recharge in the decade around 1975 resulted from nearly 2 m of rain in excess of the monthly average that fell between 1960 and 2014 followed by a nearly 4 m deficit to 2014 this excess rain coincided with two major el nino events during the maximum cool phase in the atlantic multidecadal oscillation although regional water withdrawal increased nearly 5 fold between 1980 and 2005 withdrawals represent only 2 5 of ichetucknee river flow and are less important than decadal long variations in precipitation these results suggest that groundwater management should consider climate cycles as predictive tools for future water resources

linear unit response functions as indicators of recharge areas for large karst springs abstract the delineation of groundwater recharge areas for karst springs is important for estimating groundwater supplies and for identifying sources and directions of contaminant movement this paper suggests the potential utility of spring discharge kernel functions analogous to instantaneous unit hydrographs for surface runoff in the identification of the recharge areas of large springs examples from southeastern missouri u s a show that when consistent methods are used for baseflow separation and excess precipitation determinations derived linear kernels are most physically realistic and have the least fitting error when the assumed spring recharge area is consistent with tracer study results

tidal pumping of water between bahamian blue holes aquifers and the ocean summary exchange of water between conduits and aquifers occurs in many continental karst settings because allogenic recharge from confined catchments causes hydraulic heads in conduits to increase faster than in the aquifer most modern carbonate platforms lack allogenic catchments allowing rainfall to recharge the aquifer uniformly without sufficiently altering head gradients to drive exchange between conduits and aquifers some modern carbonate platforms experience tidal variations which could lead to head gradients that drive exchange to determine the impact of tides on exchange we measured water elevations at high temporal resolution in the ocean blue holes and wells on san salvador island and rum cay bahamas dampened tidal amplitudes inland indicate diffusivity values transmissivity storativity at wells were around 1 3 10 6 m 2 day and at blue holes were around 76 9 10 6 m 2 day assuming dampening results only from head loss these diffusivity values were used to estimate hydraulic conductivity values of around 4 0 294 10 4 m day although they may be lower if the aquifer thickness is greater than the estimated 10 m we assume wells provide values representing greater influence of matrix permeability than values from blue holes which represent a greater influence of conduit permeability differences in permeability drive exchange because hydraulic head in the aquifer lags the head in the conduits and blue hole through a tidal cycle if negligible head loss occurs with flow through conduits as reflected in lag times less than 10 min then differences in elevation at the blue holes and the ocean may represent exchange of water between the blue hole and matrix porosity with this assumption about 0 9 m 3 of water is exchanged per half tidal cycle or about 1 of the complete change in volume of water in the blue hole per half tidal cycle this volume represents an average penetration into the aquifer of 6 8 mm although it could be further in zones with elevated permeability exchange is reflected in systematic changes in specific conductivity and ph between high and low tide and the ph changes reflect reaction with the surrounding aquifer material since exchange occurs twice daily cumulative alteration of aquifer porosity could be large tidal exchange should decrease away from the coast on large carbonate platforms so that tidally driven alteration will be enhanced at the rims over interior of carbonate platforms

isostatic uplift driven by karstification and sea level oscillation modeling landscape evolution in north florida isostatic uplift of tectonically stable passive margin lithosphere can preserve a record of paleo shoreline position by elevating coastal geomorphic features above the influence of nearshore wave activity conversely depositional ages and modern elevations of these features can provide valuable information about the uplift history of a region we present a numerical model that combines sea level oscillation subaerial exposure a precipitation karstification function and isostatic uplift to explore the dynamic geomorphic behavior of coastal carbonate landscapes over multiple sea level cycles the model is used to estimate ages of coastal highstand depositional features along the atlantic coast of north florida numerical simulations using current best estimates for pleistocene sea level and precipitation histories suggest ages for trail ridge 1 44 ma the penholoway terrace 408 ka and the talbot terrace 120 ka that are in agreement with fossil evidence in addition model results indicate that the rate of karstification void space creation or equivalent surface lowering rate within the north florida platform is 3 5 times that of previous estimates 1 m 11 2 k y vs 1 m 38 k y and uplift rate is 2 times as high as previously thought 0 047 mm yr vs 0 024 mm yr this process has implications for landscape evolution in other carbonate settings and may play an underappreciated role within the global carbon cycle

organic and inorganic carbon dynamics in a karst aquifer santa fe river sink rise system north florida usa spatiotemporal variations in dissolved organic carbon doc dissolved inorganic carbon dic major ions concentrations and other geochemical parameters including stable carbon isotopes of dic 13cdic were measured in surface water and deep and shallow well water samples of the santa fe river sink rise eogenetic karst system north florida usa three end member water sources were identified one doc rich dic poor 13cdic depleted one doc poor dic rich 13cdic enriched and one enriched in major ions given their spatiotemporal distributions they were presumed to represent soil water upper aquifer groundwater and deep aquifer water sources respectively using assumed ratios of na cl and so42 for each end member a mixing model calculated the contribution of each water source to each sample then chemical effects of biogeochemical reactions were calculated as the difference between those predicted by the mixing model and measured species concentrations in general carbonate mineral dissolution occurred throughout the sink rise system surface waters were net autotrophic and the subsurface was in metabolic balance i e no net doc or dic production or consumption however there was evidence for chemolithoautotrophy perhaps by hydrogen oxidizing microbes at some deep aquifer sites mineralization of this autochthonous natural dissolved organic matter ndom led to localized carbonate dissolution as did surface water derived ndom supplied to shallow well sites during the highest flow periods this study demonstrates linkages between hydrology abiotic and microbial processes and carbon dynamics and has important implications for groundwater quality karst morphologic evolution and hydrogeologic projects such as aquifer storage and recovery in karst systems

eruptive history of the late quaternary ciomadul csomad volcano east carpathians part i timing of lava dome activity located at the southern tip of the intra carpathian volcanic range in romania and composed of a dozen dacitic lava domes the ciomadul csomad volcanic complex is the youngest eruptive centre of the carpatho pannonian region whereas in the last decade the explosive history of ciomadul since 50 ka has been well constrained by numerous studies the chronology of the dome sequence still lacks robust chronological constraints and an extended analysis of all available data here we apply a detailed k ar dating approach to refine the chronology of the lava dome eruptions using the unspiked k ar cassignol gillot technique our dating focused on the most voluminous central part of the lava dome complex new eruption ages were determined following a strict separation of 10 g of groundmass from about 3 kg of unaltered sample rocks thereby isolating material whose cooling was contemporaneous with the eruption the newly applied methodology mainly consisting of a double full preparation first at larger grain size 0 4 mm and then at 100 m provides an appropriate procedure to separate suitable material to obtain the k ar age of the eruption i e the sample s groundmass in which there is no risk of the presence of older inherited crystals our new geochronological data set gives an improved insight into the temporal construction of the ciomadul volcanic complex where due to the method applied here all ages are younger than those from previous studies that used whole rock k ar ages our new results show that ciomadul s volcanic activity began with the construction of the south eastern peripheral domes from ca 850 ka to 440 ka after a ca 250 ky long repose period the activity resumed in the northern part at around 200 ka with subsequent domes emplaced between 200 and 130 ka aligned roughly north south in the western central part of the complex following a 30 ky long quiescence period the eastern central domes formed between 100 and 60 ka in addition to the chronological history of lava dome volcanism we also investigated the sequence of crystallization of mineral phases present in the lavas with respect to the modification of eruption ages ages obtained on pure minerals plagioclase amphibole and biotite are systematically older than those obtained on groundmass showing that most of them formed up to 1 85 myr before eruption in a long lived pre ciomadul magmatic system crystal size distribution csd data support the age contrasts between juvenile groundmass and older inherited minerals after injection of new magma and convective mixing with crystal clots ascent of the resulting mixture led to eruptions of material representing contrasting ages

years to weeks of seismic unrest and magmatic intrusions precede monogenetic eruptions seismic deformation and gas activity unrest typically precedes volcanic eruptions tracking the changes of this activity with monitoring data makes it increasingly possible to successfully forecast eruptions from stratovolcanoes however this is not the case for monogenetic volcanoes eruptions from these volcanoes tend to be small but are particularly difficult to anticipate since they occur at unexpected locations and there is very limited instrumental monitoring data many monogenetic volcanic fields occur in high density populated areas and or tourist destinations and thus even a small eruption can have a major economic and societal impact we have gathered the available instrumental data for unrest and combined it with new historical accounts of seismicity our occurrences are mainly from high magmatic flux oceanic islands canary islands iceland papua new guinea mexico and japan we find that seismic activity may start one or two years before eruption but it intensifies at approximately two or three months and one or two weeks the petrological and geochemical characteristics of the deposits show that multiple magma batches interacted in a subvolcanic reservoir and multiple intrusions occurred on a similar time scales to the seismicity we propose a general model for these eruptions where early dike intrusions in the crust do not erupt e g stalled intrusions and make small plumbing systems but they probably are key in creating a thermal and rheological pathway for later dikes to be able to reach the surface these observations provide a conceptual framework for better anticipating monogenetic eruptions in similar settings and magmatic fluxes and should lead to improved strategies for mitigation of their associated hazards and risks

parsimonious recharge discharge modeling in carbonate fractured aquifers the groundwater flow in the gran sasso aquifer central italy summary in the carbonate fractured aquifer of the gran sasso central italy numerical simulations have been applied to validate a conceptual model of the recharge discharge cycle at regional scale to identify the effective aquifer features that mostly affect the spring discharges simple parsimonious models based on few key parameters whose effective values are well constrained by previous hydrological geological studies are used input data are represented by infiltration calculated considering rainfall snowmelt and runoff in endorheic basins and effective permeability distribution estimated by geological tectonic and hydrogeological settings of the aquifer discharges of tapped springs and tunnel drainages for the 1999 2009 period have been simulated after estimating the recharge area of each monitored spring by the hydrogeological setting and checking them by mean isotope elevation values discharge monitoring has been compared with the simulations obtaining a good agreement both at seasonal and yearly time basis the simulations will also be useful for previewing discharge in drought period and evaluating protection zones of tapped springs in the territory of a national park

modeling karst spring hydrograph recession based on head drop at sinkholes abstract spring discharge often responds to rainfall with a rapid increase followed by a slower recession and the mode of recession is often exponential like we propose a new model of the response of spring discharge to rainfall based on the square law for turbulent conduit flow the new non exponential model is compared against the exponential model under specific constraints a hydrograph of st marks river in florida is used to illustrate that when the change in sinkhole head defined as the hydraulic head at the upstream end of the karst conduit connected to the spring is relatively small the solution of the new model is close to that of the exponential model which extends the validity and application of the exponential solution when the change in sinkhole head is very large the solutions from the two models clearly differ from each other limitations of the non exponential model are analyzed by simulation of a hydrograph observed downstream of wakulla springs it is concluded that both solutions are applicable when spring response is smaller than or comparable to the base flow but are nonphysical when the response is much larger than the base discharge

exchange of water between conduits and matrix in the floridan aquifer flow through carbonate aquifers may be dominated by conduits where they are present by intergranular or fracture porosity where conduits are missing or may occur in conduits and matrix porosity where both are well developed in the latter case the exchange of water between conduits and matrix could have important implications for water management and hydrodynamic modeling an extensive conduit system has been mapped by dye trace studies and cave diving exploration at the santa fe sinkrrise system located in largely unaltered rocks of the floridan aquifer of north central florida in this area the santa fe river flows underground at the river sink and returns to the surface 5 km to the south at a first magnitude spring called the river rise limited data show that discharge is greater by 27 96 at the river rise than at the sink and that the downstream increase in discharge is inversely related to discharge of the river natural so 2y 4 concentrations indicate that 25 of the water discharging from the rise originates from the sink during low flow conversely so 2y and other solute concentrations indicate that most of the water discharging from the rise originates from 4 the sink during floods ar 40 decrease in na q and cl y concentrations over a 5 1r2 month period at a down gradient water supply well may reflect flow of dilute flood water from the conduits into and through the matrix at rates estimated to be between 9 and 65 mrday calcium concentrations remain constant through time at the well although flood waters have 90 lower ca 2q concentrations than ground water perhaps reflecting dissolution of the matrix rocks this apparent exchange of water between matrix and conduits is important for regional ground water quality and dissolution reactions q 2001 published by elsevier science b v

can we infer the age of karst conduit from the profile of potentiometric surface abstract the floridan aquifer consists of a high presence of karst features that make the landscape prone to sinkholes karst conduits can conduct high amounts of water and affect processes such as groundwater transport a karst conduit evolution model based on dissolution chemistry is applied to the silver springs springshed in ocala florida the model is able to reproduce the observed potentiometric head profiles more accurately than the one dimensional groundwater flow model for confined aquifer with leaky conditions in addition based on the initial fracture geometry and dissolution chemistry the model predicts the age of the conduits from the analyzed head profiles to be approximately 9 60 myrs old the understanding of the karst conduit geometric evolution and mapping can improve conduit age prediction as well as better characterize conduit flow patterns and subsequent groundwater processes

formation of volcanogenic massive sulfide deposits the kuroko perspective abstract the main objective of this paper is to identify the geochemical hydrological igneous and tectonic processes that led to the variations in the physical size geometry and chemical mineralogy metal ratios and zoning characteristics of volcanogenic massive sulfide deposits with respect to space from a scale of mining district size area to a global scale and time from a all volcanogenic massive sulfide deposits vmsds appear to have formed in extensional tectonic settings such as at mid ocean spreading centers backarc spreading centers and intracontinental rifts and failed rifts all vmsds appear to have formed in submarine depressions by seawater that became ore forming fluids through interactions with the heated upper crustal rocks submarine depressions especially those created by submarine caldera formation and or by large scale tectonic activities e g rifting become most favorable sites for the formation of large vmsds because of hydrological physical and chemical reasons the fundamental processes leading to the formation of vmsds include the following six processes 1 1 intrusion of a heat source typically a 10 3 km size pluton into an oceanic crust or a submarine continental crust causes deep convective circulation of seawater around the pluton the radius of a circulation cell is typically 5 km the temperature of fluids that discharge on the seafloor increases with time from the ambient temperature to a typical maximum of 350 c and then decreases gradually to the ambient temperatures in a time scale of 100 to 10 000 years the majority of sulfide and sulfate mineralization occurs during the waxing stage of hydrothermal activity 2 2 reactions between low temperature t 2 4 as disseminated gypsum and anhydrite in the country rocks 3 3 reactions of the modified seawater with higher temperature rocks at depths during the waxing stage cause the transformation of the seawater to metal and h 2 s rich ore forming fluids the metals and sulfide sulfur are leached from the county rocks the previously formed gypsum and anhydrite are reduced by fe 2 bearing minerals and organic matter providing additional h 2 s the mass of high temperature rocks that provide the metals and reduced sulfur is typically 10 11 tons 40 km 3 in volume the roles of magmatic fluids or gases are minor in most massive sulfide systems except for so 2 to produce acid type alteration in some systems 4 4 reactions between the ore forming fluids and cooler rocks in the discharge zone cause alteration of rocks and precipitation of some ore minerals in the stockwork ores 5 5 mixing of the ore forming fluids with local seawater within unconsolidated sediments and or on the seafloor causes precipitation of primitive ores with the black ore mineralogy sphalerite galena pyrite barite anhydrite 6 6 reactions between the primitive ores with later and hotter hydrothermal fluids cause transformation of primitive ores to matured ores that are enriched in chalcopyrite and pyrite variations in the mineralogical and elemental characteristics the geometry and the size of submarine hydrothermal deposits are controlled by the following four parameters 1 a the chemical and physical characteristics of seawater composition temperature density which depend largely on the geographical settings e g equatorial evaporating basins 2 b the chemical and physical characteristics of the plumbing system lithology fractures 3 c the thermal structure of the plumbing system which is determined largely by the ambient geothermal gradient and the size and temperature of the intrusive and 4 d the physical characteristics of the seafloor depth basin topography for example the submarine hydrothermal deposits developed in basaltic plumbing systems are generally poor in pb and ba compared to those developed in felsic plumbing systems the lower temperature systems are generally poorer in sulfides but richer in iron oxides and sulfates the higher temperature and larger hydrothermal systems tend to produce chalcopyrite and pyrite rich ores contrasts in the metal ratios between the noranda type archean vmsds and the younger vmsds reflect the differences in the geothermal gradient of the plumbing systems the submarine hydrothermal deposits developed in the near equatorial regions tend to form large continuous bedded type ores because of the likeliness of creating large stratified basins the basic processes of submarine hydrothermal mineralization have remained essentially the same throughout the geologic history from at least 3 5 billion year ago to the present

analysis of well hydrographs in a karst aquifer estimates of specific yields and continuum transmissivities abstract hydrograph analysis techniques have been well developed for hydrographs obtained from streams and springs where data are cast in terms of total discharge the data obtained from well hydrographs provide water level versus time hence a method of hydrograph analysis is required for situations in which only water level data are available it is assumed here that three segments on a recession curve from wells in a karst aquifer represent drainage from three types of storage conduit c fracture f and matrix m hydrographs from several wells in a karst aquifer are used to estimate the specific yields sy associated with each portion of the aquifer c f m as well as continuum transmissivities t data from three short injection tests at one well indicate continuum t at this well bore is approximately 5 m2 day 1 and tests at numerous other wells in the aquifer yield results between 1 and 7 m2 day 1 the t estimated with well hydrographs from two storms indicates a t of 9 8 m2 day 1 well developed conduit systems in which water levels in wells show a flashy response typically show sys of 1 10 4 1 10 3 and 3 10 3 for c f and m respectively less well developed conduit areas show more nearly equal sys 8 6 10 4 1 3 10 3 3 10 3 areas with no evidence for the presence of conduits have only one or in some cases two slopes on the recession curve in these cases water level responses are slow recession curves with a single slope represent drainage from only the lower t matrix those with two slopes have an additional more rapid response segment on the recession curve which represents drainage from the higher t lower sy fractures in the system

construction of the north head maungauika tuff cone a product of surtseyan volcanism rare in the auckland volcanic field new zealand the auckland volcanic field avf comprises at least 52 monogenetic eruption centres dispersed over 360 km2 eruptions have occurred sporadically since 250 ka predominantly when glacio eustatic sea levels were lower than today now that around 35 of the field is covered by shallow water up to 30 m depth any eruption occurring in the present or near future within this area may display surtseyan dynamics the north head tuff cone evidences eruptive dynamics caused by magma interaction with seawater the first stages of the eruption comprise a phreatomagmatic phase that built a 48 m high tuff cone north head tuff deposits contain few lithic fragments 10 vol and are characterized by deposits from collapsing tephra jets and fall from relatively wet tephra columns the conditions needed for this eruption existed between 128 and 116 ka when the sea level in the auckland area was at least 10 12 m above the pre eruptive surface the hazards associated with this type of eruption pose a risk to the densely populated coastal residential zones and the activities of one of the busiest harbours in new zealand

influences on the variability of eruption sequences and style transitions in the auckland volcanic field new zealand abstract monogenetic basaltic volcanism is characterised by a complex array of eruptive behaviours reflecting spatial and temporal variability of the magmatic properties e g composition eruptive volume magma flux as well as environmental factors at the vent site e g availability of water country rock geology faulting these combine to produce changes in eruption style over brief periods minutes to days in many eruption episodes monogenetic eruptions in some volcanic fields often start with a phreatomagmatic vent opening phase that later transforms into dry magmatic explosive or effusive activity with a strong variation in the duration and importance of this first phase such an eruption sequence pattern occurred in 83 of the known eruption in the 0 25 my old auckland volcanic field avf new zealand in this investigation the eruptive volumes were compared with the sequences of eruption styles preserved in the pyroclastic record at each volcano of the avf as well as environmental influencing factors such as distribution and thickness of water saturated semi to unconsolidated sediments topographic position distances from known fault lines the avf showed that there is no correlation between ejecta ring volumes and environmental influencing factors that is valid for the entire avf in contrary using a set of comparisons of single volcanoes with well known and documented sequences resultant eruption sequences could be explained by predominant patterns of the environment in which these volcanoes were erupted based on the spatial variability of these environmental factors a first order susceptibility hazard map was constructed for the avf that forecasts areas of largest likelihood for phreatomagmatic eruptions by overlaying topographical and shallow geological information combining detailed phase by phase breakdowns of eruptive volumes and the event sequences of the avf along with the new susceptibility map more realistic eruption scenarios can be developed for different parts of the volcanic field this approach can be applied to tailoring field and sub field specific hazard forecasting at similar volcanic fields worldwide

geochemical and statistical evidence of recharge mixing and controls on spring discharge in an eogenetic karst aquifer summary information about sources of recharge distributions of flow paths and the extent of water rock reactions in karst aquifers commonly result from monitoring spring chemistry and discharge to investigate the relationship between spring characteristics and the complexities of karst aquifers we couple variations in surface and groundwater chemistry to physical conditions including river stage precipitation and evapotranspiration et within a sink rise system through a 6 km portion of the upper floridan aquifer ufa in north central florida principal component analysis pca of time series major element compositions suggests that at least three sources of water affect spring discharge including allogenic recharge into a swallet diffuse recharge through a thin vadose zone and water upwelling from deep within the aquifer the deep water source exerts the strongest influence on water chemistry by providing a majority of na mg2 k cl and so 4 2 to the system anomalously high temperature at one of several monitoring wells reflects vertical flow of about 1 m year mass balance calculations suggest diffuse recharge and deep water upwelling can provide up to 50 of the spring discharge however their contributions depend on head gradients between the conduit and surrounding aquifer matrix which are influenced by variations in precipitation et and river stage our results indicate that upwelling from deep flow paths may provide significant contributions of water to spring discharge and that monitoring only springs limits interpretations of karst systems by masking critical components of the aquifer such as water sources and flow paths these results also suggest the matrix in eogenetic aquifers is a major pathway for flow even in a system dominated by conduits

imaging spectroscopy earth and planetary remote sensing with the usgs tetracorder and expert systems 1 imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis we describe a new system that is effective at material identification and mapping a set of algorithms within an expert system decision making framework that we call tetracorder the expertise in the system has been derived from scientific knowledge of spectral identification the expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis additional expert rules and algorithms can be applied based on initial results and more decisions are made until spectral analysis is complete because certain spectral features are indicative of specific chemical bonds in materials the system can accurately identify and map those materials in this paper we describe the framework of the decision making process used for spectral identification describe specific spectral feature analysis algorithms and give examples of what analyses and types of maps are possible with imaging spectroscopy data we also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials we demonstrate the applications of tetracorder to identify and map surface minerals to detect sources of acid rock drainage and to map vegetation species ice melting snow water and water pollution all with one set of expert system rules mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering mineralization hydrothermal alteration and other geologic processes environmental site assessment such as mapping source areas of acid mine drainage has resulted in the acceleration of site cleanup saving millions of dollars and years in cleanup time imaging spectroscopy data and tetracorder analysis can be used to study both terrestrial and planetary science problems imaging spectroscopy can be used to probe planetary systems including their atmospheres oceans and land surfaces

regional scale transport in a karst aquifer 1 component separation of spring flow hydrographs large fluctuations in ca and mg concentrations occur in the discharge of karst springs in southeastern missouri after major storm events rapid flow of relatively dilute storm derived water through solution conduits in the aquifer causes the fluctuations in chemistry a cation balance for the discharge of one spring indicates that about 25 of the total spring flow is storm derived water these storm derived contributions reach a maximum during the recession of storm responses in the spring flow hydrograph at the peak of the responses spring flow is composed primarily of prestorm water that has been displaced in the conduit system by the storm derived water the observed chemical fluctuations and hydrograph components differ from those observed in streamflow where the time of the maximum dilution usually coincides with the time of peak discharge

do phreatomagmatic eruptions at ubehebe crater death valley california relate to a wetter than present hydro climate of the region a novel application of 10 be surface exposure dating is presented to determine the timing of phreatomagmatic eruptions at ubehebe crater and to test the idea that volcanism may relate to a wetter than present hydro climate twelve of the fifteen ages obtained lie between 0 8 and 2 1 ka while three samples give older mid holocene ages the cluster between 0 8 and 2 1 ka is interpreted as encompassing the intervalof volcanicactivityduringwhich ubehebe crater was formed the remaining older ages are inferred to date eruptions at the older neighboring craters the main and most recent period of activity encompasses the medieval warm period an interval of prolonged drought in the american southwest as well as slightly wetter conditions prior to the medieval warm period phreatomagmatic activity under varied hydrologic conditions casts doubt on the idea that eruptive timing relates to a wetter hydro climate instead the presence of a relatively shallow modern water table suggests that sufficient groundwater was generally available for phreatomagmatic eruptions at the ubehebe site in spite of prevailing arid conditions this and the youth of the most recent activity suggest that the ubehebe volcanic field may constitute a more significant hazard than generally appreciated citation sasnett p b m goehring n christie blick and j m schaefer 2012 do phreatomagmatic eruptions at ubehebe crater death valley california relate to a wetter than present hydro climate geophys res lett 39 l02401

water exchange and pressure transfer between conduits and matrix and their influence on hydrodynamics of two karst aquifers with sinking streams summary karst aquifers are heterogeneous media where conduits usually drain water from lower permeability volumes matrix and fractures for more than a century various approaches have used flood recession curves which integrate all hydrodynamic processes in a karst aquifer to infer physical properties of the movement and storage of groundwater these investigations typically only consider flow to the conduits and thus have lacked quantitative observations of how pressure transfer and water exchange between matrix and conduit during flooding could influence recession curves we present analyses of simultaneous discharge and water level time series of two distinctly different karst systems one with low porosity and permeability matrix rocks in southern france and one with high porosity and permeability matrix rocks in north central florida usa we apply simple mathematical models of flood recession using time series representations of recharge storage and discharge processes in the karst aquifer we show that karst spring hydrographs can be interpreted according to pressure transfer between two distinct components of the aquifer conduit and matrix porosity which induce two distinct responses at the spring water exchange between conduits and matrix porosity successively control the flow regime at the spring this exchange is governed by hydraulic head differences between conduits and matrix head gradients within conduits and the contrast of permeability between conduits and matrix these observations have consequences for physical interpretations of recession curves and modeling of karst spring flows particularly for the relative magnitudes of base flow and quick flow from karst springs finally these results suggest that similar analyses of recession curves can be applied to karst aquifers with distinct physical characteristics utilizing well and spring hydrograph data but information must be known about the hydrodynamics and physical properties of the aquifer before the results can be correctly interpreted

physical response of a karst drainage basin to flood pulses example of the devil s icebox cave system missouri usa abstract in karst aquifers water moves from the recharge area sinkhole plains and swallets to the discharge area springs traveling kilometers through the groundwater system in a period of hours to days transit times through karst aquifers are a function of the conduit geometry and connectedness intensity and duration of the recharge event and antecedent soil moisture often many of these factors are unknown or difficult to quantify therefore predicting the response of a karst basin to recharge is difficult numerous researchers have attempted to understand the response of a karst basin but a good understanding of whether the response is dependent on local features or regional effects is currently lacking from april 1994 to may 1995 flood pulse hydrographs from a karst aquifer with well developed and well documented conduits devil s icebox cave system were obtained from a gaging station near the spring of the karst basin data were also collected from within the conduit system in an attempt to determine whether flow was locally controlled by constrictions in the conduits based on an application of bernoulli s equation analyses of the changes in kinetic head and potential head over time indicated local control during storm events the observed sediment patterns and water level variations also support localized flow control during storm events a numerical model of the constrictions was tested and reproduced the responses observed at the spring during initial periods of storm events the model illustrated that the constricted flow was very sensitive to recharge it also illustrated the transition from local control due to constriction to regional controls due to the aquifer matrix

formation of phreatic caves in an eogenetic karst aquifer by co2 enrichment at lower water tables and subsequent flooding by sea level rise formation of extensive phreatic caves in eogenetic karst aquifers is widely believed to require mixing of fresh and saltwater extensive phreatic caves also occur however in eogenetic karst aquifers where fresh and saltwater do not mix for example in the upper floridan aquifer these caves are thought to have formed in their modern settings by dissolution from sinking streams or by convergence of groundwater flow paths on springs alternatively these caves have been hypothesized to have formed at lower water tables during sea level low stands these hypotheses have not previously been tested against one another analyzing morphological data and water chemistry from caves in the suwannee river basin in north central florida and water chemistry from wells in the central florida carbonate platform indicates that phreatic caves within the suwannee river basin most likely formed at lower water tables during lower sea levels consideration of the hydrological and geochemical constraints posed by the upper floridan aquifer leads to the conclusion that cave formation was most likely driven by dissolution of vadose co2 gas into the groundwater sea level rise and a wetter climate during the mid holocene lifted the water table above the elevation of the caves and placed the caves tens of meters below the modern water table when rising water tables reached the land surface surface streams formed incision of surface streams breached the pre existing caves to form modern springs which provide access to the phreatic caves phreatic caves in the suwannee river basin are thus relict and have no causal relationship with modern surficial drainage systems neither mixing dissolution nor sinking streams are necessary to form laterally extensive phreatic caves in eogenetic karst aquifers dissolution at water tables potentially driven by vadose co2 gas offers an underappreciated mechanism to form cavernous porosity in eogenetic carbonate rocks copyright 2012 john wiley sons ltd

the fekete hegy balaton highland hungary soft substrate and hard substrate maar volcanoes in an aligned volcanic complex implications for vent geometry subsurface stratigraphy and the palaeoenvironmental setting the fekete hegy volcanic complex is located in the centre of the bakony balaton highland volcanic field in the pannonian basin which formed from the late miocene to pliocene period the eruption of at least four very closely clustered maar volcanoes into two clearly distinct types of prevolcanic rocks allows the observation and comparison of hard substrate and soft substrate maars in one volcanic complex the analyses of bedding features determination of the proportion of accidental lithic clasts granulometry and age determination helped to identify and distinguish the two types of maar volcanoes ascending magma interacted with meteoric water in karst aquifers in mesozoic carbonates as well as in porous media aquifers in neogene unconsolidated wet siliciclastic sediments the divided basement setting is reflected by distinct bedding characteristics and morphological features of the individual volcanic edifices as well as a distinct composition of pyroclastic rocks country rocks in hard substrate maars have a steep angle of repose leading to the formation of steep sided cone shaped diatremes enlargement and filling of these diatreme is mainly a result of shattering material by fci related shock waves and wall rock collapse during downward penetration of the explosion locus country rocks in soft substrate maars have much shallower angles of repose leading to the formation of broad bowl shaped structures or irregular depressions enlargement and filling of these diatremes is mainly the result of substrate collapse for example due to liquefaction of unconsolidated material by fci related shock waves and its emplacement by gravity flows the fekete hegy is an important example illustrating that the substrate of a volcanic edifice has to be taken into account as an important interface which can have major control on phreatomagmatic eruptions and the resulting characteristics of the volcanic complex

effects of the conduit network on the spring hydrograph of the karst aquifer summary spring hydrograph especially the recession curve is widely used to understand the internal information of the karst aquifer however how the turbulent conduit network influences the spring hydrograph is still unclear generally the spring hydrograph could be divided into the early portion from the point recharge and late portion from the diffuse recharge in this paper modflow cfp is used to understand the influence of turbulent conduit on the spring hydrograph from the diffuse recharge and different influences of the turbulent and laminar conduit on this spring hydrograph and then a conceptual model is used to further interpret it based on the analysis results the influence of turbulent conduit on the spring hydrograph from the point recharge is also discussed for the spring hydrograph from the diffuse recharge when ignoring the storage variation of the conduit network the turbulent conduit just influences the early recession curve and this influence decreases with the spring discharge or rainfall intensity until it disappears when the spring hydrography is strongly reshaped by the storage of the turbulent conduit network only the early recession behavior is influenced by the turbulent conduit network as well however the laminar conduit network has a strongly influence on the whole recession behavior the late exponential recession coefficient decreases with the conduit diameter and conduit storage these different influences of turbulent and laminar conduit on the spring hydrograph are mainly caused by their different flow characteristics although the turbulent conduit could also strongly influence the early spring hydrograph from the point recharge the late spring hydrograph is mainly controlled by diffuse recharge and the influence from the turbulent conduit may also disappear

using hydrochemical stable isotope and river water recharge data to identify groundwater flow paths in a deeply buried karst system the deeply buried river connected xishan karst aquifer xka in western beijing china has been suffering from diminishing recharge for several decades which in turn leads to the disappearing of spring water outflows and continuously lowering of groundwater level in the area thus it is important to correctly recognize the groundwater recharge and flow paths for the sustainable development of the xka to investigate these issues the hydrochemical and isotopic compositions are analysed for both surface water and groundwater samples collected over an area of about 280 km2 results show that a the river water is characterized by high na contents b the 2h and 18o values in the river water are distinctively higher than those of groundwater samples after experiencing the long time evaporative enrichment in the upstream reservoir c the sr concentrations and 87sr 86sr ratios of groundwater clearly indicated the interaction between water and carbonate minerals but excluded the water silicate interaction and d the groundwater samples in the direct recharge area of the xka have the lowest na concentrations and the 2h and 18o values based on the large differences in the na contents and 18o values of groundwater and surface water a simple two component mixing model is developed for the study area and the fractions of the river water are estimated for groundwater samples we find that the distribution pattern of the river water fractions in the xka clearly shows a change of directions in the preferential flow path of the groundwater from its source zone to the discharge area overall our results suggest that the recharged surface water can be a useful evidence for delineating the groundwater flow path in river connected karst aquifer this study improves our understanding of the heterogeneity in karst groundwater systems

laboratory and numerical simulations of spatio temporal variability of water exchange between the fissures and conduits in a karstic aquifer abstract fissures and conduits are main void of karstic aquifer karst aquifers are highly vulnerable to contamination as water exchange between fissure system and conduit system greatly influences the karstification of limestone terrains heterogeneity of karstic aquifer and spring flow regime a two dimensional tank model was constructed and a corresponding numerical model modflow 2005 conduit flow process mode 1 cfpm1 was developed to explore the effects of rainfall intensity and intrinsic structure of karst system hydraulic conductivity of fissures and conduit diameter on conduit matrix water exchange nine different scenarios were designed to quantitatively simulate the spatial and temporal variability of water exchange between the fissures and conduits the study reproduced the area of fissure water recharging to conduit recharge zone the area of conduit water discharging to fissure water discharge zone and the area of fissure water moving laterally transport zone in both physical model and numerical model the results from rainfall scenarios show a relatively stable ratio of exchange zone recharge zone and discharge zone with increasing rainfall intensity indicating that conduit matrix water exchange is not sensitive to rainfall intensity and conduit water discharging to fissure water is just a short term phenomenon it is also found that an increase in hydraulic conductivity of fissure system enhances extensiveness of water transport but restrains conduit matrix water exchange however the enlargement of conduit can prompt the extent of conduit matrix water exchange a positive feedback between the extent of conduit matrix water exchanges and karstification can be confirmed these findings might be essential for better understanding groundwater flow dynamics in karst aquifers

forecasting transitions in monogenetic eruptions using the geologic record spatial forecasting of volcanism and associated hazards in intraplate monogenetic volcanic fields is subject to large uncertainties in both data and models we demonstrate a novel logistic regression method for mapping phreatomagmatic magmatic eruption transition susceptibility using near surface hydrologic topographic and geologic data the method is illustrated on the auckland volcanic field the location of new zealand s largest city auckland environmental factors examined for possible influence included the thickness of water saturated and porous sediments substrate type and geology vent elevation and distance from the nearest fault by comparing these factors with the volumes and styles of past eruption sequences a location specific eruption sequence forecasting model was constructed recognizing that larger and or longer eruptions are more likely to exhaust vent area sources of water estimating volcanic hazard susceptibility in this way allows more effective planning and improved preeruption preparedness between eruptions and during future volcanic crises

detrital cave sediments record late quaternary hydrologic and climatic variability in northwestern florida usa abstract detrital sediment in florida s usa submerged cave systems may preserve records of regional climate and hydrologic variability however the basic sedimentology mineralogy stratigraphic variability and emplacement history of the successions in florida s submerged caves remains poorly understood here we present stratigraphic mineralogical and elemental data on sediment cores from two phreatic cave systems in northwestern florida usa on the dougherty karst plain hole in the wall cave hitw and twin cave water flowing through these caves is subsurface flow in the apalachicola river drainage basin and the caves are located just downstream from jackson blue 1st magnitude spring 2 8 m3 s 1 discharge sedimentation in these caves is dominated by three primary sedimentary styles i ferromanganese deposits dominate the basal recovered stratigraphy which pass upsection into ii poorly sorted carbonate sediment and finally into iii fine grained organic matter gyttja deposits resolving the emplacement history of the lower stratigraphic units was hampered by a lack of suitable material for radiocarbon dating but the upper organic rich deposits have a punctuated depositional history beginning in the earliest holocene for example gyttja primarily accumulated in hitw and twin caves from 5500 to 3500 cal yr bp which coincides with regional evidence for water table rise of the upper floridian aquifer associated with relative sea level rise in the gulf of mexico and evidence for invigorated drainage through the apalachicola river drainage basin gyttja sediments were also deposited in one of the caves during the bolling allerod climate oscillation biologically these results indicate that some floridian aquatic cave stygobitic ecosystems presently receive minimal organic matter supply in comparison to prehistoric intervals the pre holocene poorly sorted carbonate sediment contains abundant invertebrate fossils and likely documents a period of enhanced limestone dissolution and cave formation speleogenesis during lower paleo water levels further work is still required to a determine whether precipitation of the ferromanganese deposits is inorganically or biologically mediated b temporally constrain the emplacement history of the primary sedimentary styles and c determine the full geographic extent of these sedimentary signals however these preliminary observations suggest that sedimentation in the inland underwater caves of northwestern florida is related to quaternary scale hydrographic variability in the apalachicola river drainage basin in response to broader ocean and atmospheric forcing

simulating long term nitrate n contamination processes in the woodville karst plain using cfpv2 with umt3d summary a research version of cfp conduit flow process code cfpv2 is applied with umt3d to simulate long term 1966 2018 nitrate n contamination transport processes in the woodville karst plain wkp northern florida where karst conduit networks are well developed groundwater flow in the wkp limestone porous matrix is simulated using darcy s law and non laminar flow within conduits is described by darcy weisbach equation nitrate n conduit transport and advective exchanges of groundwater and nitrate n between conduits and limestone matrix are calculated by cfpv2 and umt3d instead of modflow and mt3dms since reynolds numbers for flows in conduits are over the criteria of laminar flow the developed numerical model is calibrated by field observations and then applied to simulate nitrate n transport in the wkp the numerical simulations verify the theories that two sprayfields near the city of tallahassee and septic tanks in the rural area are major nitrate n point sources within the wkp high nitrate n concentrations occur near lost creek sink and conduits of wakulla spring and spring creek springs where aquifer discharge groundwater conduit networks control nitrate n transport and regional contaminant distributions in the wkp as nitrate n is transported through conduits rapidly and spread over large areas

volcanz a volcanic loss model for auckland new zealand abstract volcanz is a probabilistic volcanic loss model developed for the auckland region in new zealand that currently considers tephra fall hazards from the auckland volcanic field avf tuhua volcano okataina volcanic centre taupo volcano tongariro volcanic centre and egmont volcano in this first version of the model structural and non structural damage to residential building envelopes and associated cleanup costs are calculated using monte carlo simulation volcanz assigns a minimum and maximum damage value to groups of buildings for every simulation dependent on tephra thickness a central damage value representing loss as a percentage of total replacement cost is then randomly selected between these limits even with small thickness falls non structural damage is expected to roof and wall coatings air conditioning units aerials and satellite dishes due to the corrosive and abrasive properties of tephra an average loss of 583 attributed to non structural damage was assigned to all residential buildings impacted by any thickness of tephra greater than 0 1 mm the costs of tephra removal from buildings cleaning of building exteriors and tephra transport and disposal are also calculated within the model assuming much of the cleanup process will be carried out by homeowners losses from all simulations are plotted against calculated average recurrence intervals aris to produce loss curves structural damage does not become apparent until aris of approximately 8000 years 1 billion losses due to structural damage occur at about 35 000 years and this increases to about 26 billion at 1 million years loss due to non structural damage is constant at approximately 160 million for aris above about 600 years between 600 and 3000 years cleanup loss is approximately 50 million increasing to over 450 million at a return period of 1 million years at aris between 600 and 3000 years total loss is approximately 210 million increasing to 10 billion at 100 000 years and over 26 billion at 1 million years because we only consider residential building damage and associated cleanup these values greatly underestimate total loss from the next volcanic event to impact auckland loss calculations will be improved by adding additional hazard and loss modules to volcanz resulting in a complete catastrophe loss model

characterization of groundwater and surface water mixing in a semiconfined karst aquifer using time lapse electrical resistivity tomography groundwater flow in karst includes exchange of water between large fractures conduits and the surrounding porous matrix which impacts both water quality and quantity electrical resistivity tomography combined with end member mixing analysis emma and numerical flow and transport modeling was used to study mixing of karst conduit and matrix waters to understand spatial and temporal patterns of mixing during high flow and base flow conditions to our knowledge this is the first time emma and synthetic geophysical simulations have been combined here we interpret an 8 week time lapse electrical resistivity data set to assess groundwater surface mixing we simulate flow between the karst conduits and the porous matrix to determine fractions of water recharged to conduits that has mixed with groundwater stored in the pore space of the matrix using a flow and transport model in a synthetic time lapse resistivity inversion comparing the field and synthetic inversions our results enable us to estimate exchange dynamics spatial mixing and flow conditions results showed that mixing occurred at a volumetric flux of 56 m3 d with a dispersivity around 1 69 m during the geophysical experiment for these conditions it was determined that conduit water composition ranged from 75 groundwater during base flow conditions to less than 50 groundwater in high flow conditions though subject to some uncertainties the time lapse inversion process provides a means to predict changing hydrologic conditions leading to mixing of surface water and ground water and thus changes to water quantity and quality as well as potential for water rock reactions in a semiconfined sink rise system

δd and δ18o variations of the magmatic system beneath deception island volcano antarctica implications for magma ascent and eruption forecasting abstract geochemistry of volatiles in active volcanoes provides insights into the magmatic processes and evolution at depth such as magma evolution and degassing which can be implemented into volcanic hazards assessment deception island is one of the most active volcanoes in antarctica with more than twenty explosive eruptions documented over the past two centuries hydrogen and oxygen isotopic variations in the volatiles trapped in the deception island rocks glass and melt inclusions in phenocrysts provide essential information on the mechanisms controlling the eruptive history in this volcanic suite thus understanding the petrological and related isotopic variations in the island has the potential to foresee the possible occurrence and its main eruptive features of a future eruption the new isotopic results of this study combined with exhaustive petrologic knowledge reveal in deception island i fast ascent and quenching of most magmas preserving pre eruptive magmatic signal of water contents and isotopic ratios with local modification by rehydration due to glass exposition to seawater and by meteoric and fumarolic waters ii a plumbing system s variable with time and currently dominated by closed system degassing leading to explosive eruptions iii control on the interactions of ascending magmas with the surface waters producing hydrovolcanic activity throughout the two main fault systems in deception island and at different magma stagnation depths these results can be considered in further studies of volcanic monitoring to improve the capability to interpret geophysical data and signals recorded during volcanic unrest episodes and hence forecast volcanic eruptions and related hazards

how can satellite imagery be used for mineral exploration in thick vegetation areas the hokuroku district northern japan is globally recognized for rich ore deposits kuroko and vein types which have been thoroughly explored under thick vegetation cover this situation is ideal to evaluate the effects of ore deposits on vegetation anomalies through geobotanical remote sensing here we present novel methods to detect vegetation anomalies caused by ore deposits and verify their usefulness by comparing the anomalies with a deposit potential map produced from multiple geological data we use the reflectance spectra of landsat etm images acquired in summer and autumn to calculate a vegetation index for plant physiological activity a key variable to detect the anomalies is a variation of vegetation index with time at each pixel difference in variation is enlarged by a sequence of image enhancement methods for the detection we find that the vegetation anomalies defined by the large ratios correspond well to the high potential zones of ore deposits and known major deposits consequently our methods can extend the applicability of remote sensing based mineral exploration to the areas covered by thick vegetation in addition to traditional arid and semi arid areas this article is protected by copyright all rights reserved

assessment of different topographic corrections in landsat tm data for mapping vegetation types 2003 different methods for topographic correction of landsat thematic mapper images have been assessed in the context of mapping vegetation types the best results were obtained with a variation of the c method which takes into account the overcorrection of low illuminated slopes by the original c method the performance of this method was tested using two criteria the changes in the spectral characteristics of the image and the reduction in standard deviation of each vegetation type after the correction

development of a discrete continuum vdfst cfp numerical model for simulating seawater intrusion to a coastal karst aquifer with a conduit system a hybrid discrete continuum numerical model variable density flow and solute transport conduit flow process vdfst cfp is developed to simulate seawater intrusion to a coastal karst aquifer with a conduit network the darcy weisbach equation is applied to simulate the nonlaminar groundwater flow in the conduit system that is conceptualized as pipes while the darcy equation is used for laminar groundwater flow in the continuum porous medium density dependent groundwater flow with appropriate additional density terms in the conduit is analytically derived the flow and transport equations are coupled and numerically solved by the finite difference method with an implicit iteration procedure two synthetic benchmarks are developed to compare the vdfst cfp model results with other numerical models such as the variable density seawat constant density continuum modflow mt3dms and constant density discrete continuum cfpv2 umt3d models the vdfst cfp model compares reasonably well with the other model results in both conduit and porous medium domains and well describes water and salt exchange between the two systems under turbulent flow conditions within the conduit the darcy weisbach equation calculates the flow rate more accurately without overestimation by the darcy equation sensitivity analysis indicates that conduit diameter friction factor matrix hydraulic conductivity and effective medium porosity are important parameters in the vdfst cfp model the pros and cons of the vdfst cfp model are discussed including the model assumptions and simplifications limitations of the discrete continuum modeling method and the convergence criteria in general the newly developed vdfst cfp model provides a new numerical modeling method for simulating seawater intrusion in a coastal karst aquifer with conduits

pitfalls in application of the conventional chloride mass balance cmb in karst aquifers and use of the generalised cmb method there is unanimity in the literature that chloride mass flux crossing the piezometric surface requires a steady state for the saturated or unsaturated version of the conventional chloride mass balance cmb method to apply data indicate that chloride concentration in point recharge fluxes crossing the piezometric surface can remain at or near surface runoff chloride concentrations rather than finding equilibrium with groundwater chloride preferential groundwater flows were observed through an interconnected network of highly permeable zones with groundwater mixing along flow paths measurements of salinity and chloride indicated that fresher water pockets exist at point recharge locations a stable and measurable fresh water plume develops only when a large quantity of surface water enters the aquifer as a point recharge in such circumstances assumptions and boundary conditions of the conventional cmb method are not met and the method requires modification to include both point and diffuse recharge mechanisms this paper describes a generalised cmb that is applicable to groundwater basins with point recharge in three case studies point recharge flux is estimated to contribute 63 85 and 98 of total recharge however long term average annual point recharge volumes are much smaller than the aquifer storage at 1 5 1 95 and 0 75 and distributed across the basins at discrete locations in the study basins conventional cmb estimated recharges are 46 20 and 11 of the recharge estimated using the generalised cmb indicating the importance of accommodating point recharge into the cmb method the generalised cmb method provides an alternative long term net recharge estimation method for groundwater basins characterised by both point and diffuse recharge

influence of diel biogeochemical cycles on carbonate equilibrium in a karst river abstract variations in temperature photosynthesis and respiration force diel variations in ph and dissolved co 2 concentrations of surface streams possibly controlling carbonate equilibrium between river water and carbonate stream beds diel cycles of water chemistry and 13 c of dissolved inorganic carbon dic were measured to assess how biogeochemical processes affect dissolution and precipitation of calcite and thus channel development in ichetucknee river a large spring fed river discharge 6 m 3 s flowing over carbonate karst terrain in north central florida usa samples were collected at a 4 h sampling interval during two one week periods and at a 1 h interval during a single 24 h period simultaneously temperature ph dissolved oxygen do and no 3 concentrations were measured using in situ sensors at 15 min or 1 h intervals ca 2 dic and no 3 concentrations decreased during the day and increased at night causing diel changes of in stream specific conductivity these changes were inversely related to diel changes in ph pco 2 and do concentrations this work shows that photosynthesis and respiration of subaquatic vegetation are the dominant processes influencing in stream diel variation during the day a simultaneous increase of 13 c dic and decrease in dic indicates that photosynthesis was the primary control on dic concentrations calcite saturation indices ranged from 0 to 0 5 with the highest value in daylight as a result of co 2 consumption causing carbonate precipitation the water remained saturated with respect to calcite at night and 13 c dic values decreased indicating that co 2 production from ecosystem respiration was the dominant process affecting dic concentrations but was insufficient to induce significant carbonate dissolution at night outgassing maintained in stream dic concentrations lower than the supersaturated dic springs source but a drop in 13 c dic indicates that ecosystem respiration had a dominant influence over outgassing although co 2 outgassing occurs it is shown to be a minor component of the dic mass balance while carbonate precipitation represents 88 of dic loss these results indicate that in stream biological processes influence carbonate mineral diagenesis in large clear water rivers

a model for calculating eruptive volumes for monogenetic volcanoes implication for the quaternary auckland volcanic field new zealand abstract monogenetic basaltic volcanism is characterised by a complex array of behaviours in the spatial distribution of magma output and also temporal variability in magma flux and eruptive frequency investigating this in detail is hindered by the difficulty in evaluating ages of volcanic events as well as volumes erupted in each volcano eruptive volumes are an important input parameter for volcanic hazard assessment and may control eruptive scenarios especially transitions between explosive and effusive behaviour and the length of eruptions erosion superposition and lack of exposure limit the accuracy of volume determination even for very young volcanoes in this study a systematic volume estimation model is developed and applied to the auckland volcanic field in new zealand in this model a basaltic monogenetic volcano is categorised in six parts subsurface portions of volcanoes such as diatremes beneath phreatomagmatic volcanoes or crater infills are approximated by geometrical considerations based on exposed analogue volcanoes positive volcanic landforms such as scoria spatter cones tephras rings and lava flow were defined by using a light detection and ranging lidar survey based digital surface model dsm finally the distal tephra associated with explosive eruptions was approximated using published relationships that relate original crater size to ejecta volumes considering only those parts with high reliability the overall magma output converted to dense rock equivalent for the post 250 ka active auckland volcanic field in new zealand is a minimum of 1 704 km3 this is made up of 1 329 km3 in lava flows 0 067 km3 in phreatomagmatic crater lava infills 0 090 km3 within tephra tuff rings 0 112 km3 inside crater lava infills and 0 104 km3 within scoria cones using the minimum eruptive volumes the spatial and temporal magma fluxes are estimated at 0 005 km3 km2 and 0 007 km3 ka the temporal volumetric evolution of auckland is characterised by an increasing magma flux in the last 40 ky which is inferred to be triggered by plate tectonics processes e g increased asthenospheric shearing and backarc spreading of underneath the auckland region

late pleistocene alberca de guadalupe maar volcano zacapu basin michoacan stratigraphy tectonic setting and paleo hydrogeological environment abstract the late pleistocene 21 000 yr bp alberca de guadalupe maar is one of the few phreatomagmatic volcanoes occurring within the scoria cone dominated plio quaternary michoacan guanajuato volcanic field the scarcity of this type of volcano implies that conditions favoring their formation are rarely met in this region we identify these factors by implementing current methods of investigation with emphasis on hydrogeological conditions we present the stratigraphy including a set of 40 ar 39 ar and 14 c dates of the se margin of the zacapu intermontane tectonic basin where the maar just forms a hole 1 km in diameter 150 m deep bearing a 9 m deep lake in the otherwise planar topography of the underlying early pleistocene lava flows of the cerro pelon scoria cone the maar is composed of typical phreatomagmatic surge deposits that are poorly sorted and rich in accidental lithics 60 wt of the deposit with few juveniles basaltic andesite sio 2 54 58 wt the entire structure is cut by an ene wsw trending normal fault and is underlain by andesite lavas and silicic ignimbrites partly inferred from xenoliths encountered in the maar deposits that are miocene to early pleistocene in age the crater is at the center of a n s elongated drainage basin surrounded by topographic highlands that channel water with high hydraulic pressure from most directions towards the location of the maar this geometric configuration was already in existence at the time of the maar forming eruption but the climate was different colder and more humid conditions during the last glacial maximum cw2 climate type annual precipitation of 1000 mm favored the saturation of the fractured shallow aquifer system hydraulic conductivity of 10 8 to 10 7 m s that supplied sufficient groundwater at a high flow rate directed towards the center of the basin upon contact near surface 150 m deep crater with steep inner walls and an underlying shallow diatreme

a new model for simulating spring discharge recession and estimating effective porosity of karst aquifers abstract quantitative analysis of recession curves of karst spring hydrographs is a vital tool for understanding karst hydrology and inferring hydraulic properties of karst aquifers this paper presents a new model for simulating karst spring recession curves the new model has the following characteristics 1 the model considers two separate but hydraulically connected reservoirs matrix reservoir and conduit reservoir 2 the model separates karst spring hydrograph recession into three stages conduit drainage stage mixed drainage stage with both conduit drainage and matrix drainage and matrix drainage stage and 3 in the mixed drainage stage the model uses multiple conduit layers to present different levels of conduit development the new model outperforms the classical mangin model and the recently developed fiorillo model for simulating observed discharge at the madison blue spring located in northern florida this is attributed to the latter two characteristics of the new model based on the new model a method is developed for estimating effective porosity of the matrix and conduit reservoirs for the three drainage stages the estimated porosity values are consistent with measured matrix porosity at the study site and with estimated conduit porosity reported in literature the new model for simulating karst spring hydrograph recession is mathematically general and can be applied to a wide range of karst spring hydrographs to understand groundwater flow in karst aquifers the limitations of the model are discussed at the end of this paper

changes in sources and storage in a karst aquifer during a transition from drought to wet conditions summary understanding the sources and processes that control groundwater compositions and the timing and magnitude of groundwater vulnerability to potential surface water contamination under varying meteorologic conditions is critical to informing groundwater protection policies and practices this is especially true in karst terrains where infiltrating surface water can rapidly affect groundwater quality we analyzed the evolution of groundwater compositions major ions and sr isotopes during the transition from extreme drought to wet conditions and used inverse geochemical modeling phreeqc to constrain controls on groundwater compositions during this evolution spring water and groundwater from two wells dominantly receiving diffuse and conduit flow termed diffuse site and conduit site respectively in the barton springs segment of the edwards aquifer central texas usa and surface water from losing streams that recharge the aquifer were sampled every 3 4 weeks during november 2008 march 2010 during this period water compositions at the spring and conduit sites changed rapidly but there was no change at the diffuse site illustrating the dual nature i e diffuse vs conduit of flow in this karst system geochemical modeling demonstrated that within a month of the onset of wet conditions the majority of spring water and groundwater at the conduit site was composed of surface water providing quantitative information on the timing and magnitude of the vulnerability of groundwater to potential surface water contamination the temporal pattern of increasing spring discharge and changing pattern of covariation between spring discharge and surface water steam recharge indicates that that there were two modes of aquifer response one with a small amount of storage and a second that accommodates more storage

lateral vent migration during phreatomagmatic and magmatic eruptions at tecuitlapa maar east central mexico abstract tecuitlapa maar located in the eastern central volcanic belt of mexico is a late quaternary 100 m deep 1 km diameter crater with an alignment of scoria cones building in height to the east within it analysis of stratigraphic sections around the maar indicates that the phreatomagmatic eruption began in the eastern part of the crater with interaction between the basaltic magma and liquefied tuffaceous sediments the explosion locus gradually moved westward as evidenced by bomb sag trajectories duneform axes and facies changes producing an elliptical crater the eruption then dried out and began to produce scoria spatter cones with nested craters that young in age and climb in height to the east along the same alignment exhibited by the phreatomagmatic eruption the lithic lapilli and ash in the deposits throughout the eruption are from the 10 40 m thick water saturated tuffaceous sediments partially exposed in the maar crater walls rather than the underlying lavas and limestones this implies that the vent migrated laterally rather than vertically during the eruption and this lack of deepening of the explosion loci may be related to the high lithologic contrast between the non consolidated sediments and the underlying fractured bedrock water movement in the bedrock would have been by fracture flow whereas movement within the sediments was through liquefaction failure and fluidization of the deposit low magma supply rates would allow collapse of the non lithified walls of the dike producing mingling and phreatomagmatic explosions whereas the same magma supply rate in fractured bedrock may seal off water access to the magma the alignment of the vents is parallel to regional structural trends so was probably set in the underlying bedrock and the distance that the vent migrated is likely related to the overall dike length the lack of fluidized sediment coating the scoria cone clasts both in the cones and in the deposits in the walls of the maar implies that the phreatomagmatic eruptions used up most of the liquefied sediment which ended the phreatomagmatic portion of the eruption the migration of the scoria cone vent loci can be explained by an actual migration of the vents or because the evidence on their locations is based on surficial crater overlap relations by a fissure eruption that closed up from the west to the east producing later activity at the taller eastern vents

transport of dissolved carbon and co2 degassing from a river system in a mixed silicate and carbonate catchment summary assessing the origin transformation and transport of terrestrially derived carbon in river systems is critical to regional and global carbon cycles particularly in carbonate terrains which represent the largest carbon reservoir on the earth s surface for this reason we evaluated sources cycling and fluxes of dissolved organic and inorganic carbon doc and dic and riverine co 2 degassing to the atmosphere in the santa fe river in north central florida a sub tropical river that flows across two distinct hydrogeological settings of a region dominated by carbonate karst one setting occurs in the upper river catchment where the carbonate floridan aquifer is confined by the siliciclastic hawthorn group while the other setting occurs in the lower catchment where the river flows across the unconfined floridan aquifer the upper catchment is characterized by doc rich and dic poor water and the dic has more variable and lower 13 c values compared to the lower catchment the river in the upper catchment degasses more co 2 to the atmosphere 1156 g c m 2 yr 1 than in the lower catchment 402 g c m 2 yr 1 because soil respired carbon and organic matter decomposition increase dissolved co 2 concentration much of which is consumed during carbonate dissolution reactions in the lower catchment the co 2 flux from the water surface to the atmosphere during a flood event is three times greater than during base flow suggesting that excess precipitation flushes soil organic carbon to the river through interflow and enhances the loss of terrestrial carbon via river water to the atmosphere our values of co 2 fluxes to the atmosphere lie within the range of fluxes from the world s rivers but fluxes from the carbonate dominated region are at the low end while fluxes from the siliciclastic region are at the high end these results indicate that catchment lithologies particularly whether carbonate or siliciclastic as well as flow are critical to carbon budgets in rivers and thus are linked to the global carbon cycle

shift from magmatic to phreatomagmatic explosions controlled by the lateral evolution of a feeder dike in the suoana kazahaya eruption miyakejima volcano japan abstract explosive phreatomagmatic eruption is one of the most hazardous eruption styles particularly in basaltic systems as the instability of the conduit system can result in a sudden and unexpected shift of eruption style from a mild effusion of lavas to violently explosive activity the geological investigations on the phreatomagmatic activities in the 7th century suoana kazahaya eruption ske of miyakejima reveal that the drop of magmatic overpressure in conduit and the distribution of groundwater controlled the occurrence of phreatomagmatic explosion the dry magmatic eruption in the initial phase of the ske indicates that the positive overpressure of magma in the propagating feeder dike prevents the invasion of external groundwater into the conduit explosive phreatomagmatic eruption occurred at the later phase of the ske from the vents in the higher elevation the drop of magmatic overpressure in the upper part of the feeder dike caused by the downslope propagation of the eruption fissure allowed groundwater inflow to the still hot and molten feeder dikes the limited distribution of phreatomagmatic activities indicated the development of shallow groundwater hosted in the porous pyroclastic deposits within a basin of less permeable older edifice as shifts of eruption style from initial magmatic to later phreatomagmatic explosive eruption style in the top of mafic volcanoes are globally observed in many mafic volcanic systems such as kilauea and mt etna this is probably a far more common eruption mechanism than previously thought and hence it needs to be considered in volcanic hazard scenario descriptions the spatial distributions of phreatomagmatic activities in the ske suggest that the detection of buried caldera structure in a volcanic edifice can indicate a potential site for phreatomagmatic explosion the monitoring of the propagation of eruption fissure and drops of magmatic pressure and flux can indicate the potential of the phreatomagmatic explosion by the invasion of groundwater into the hot conduit

structure and function of a conduit aquifer the hydrological function of a karst aquifer is strongly controlled by its physical structure observations of physical hydrology and water chemistry along with artificial tracing allow aquifer behaviour to be identified so that hypothetical aquifer structures can be envisaged such structures can be evaluated in terms of the geology and geomorphology of the area in question and explained in terms of the geomorphological evolution of the aquifer a study of the castleguard meadows karst aquifer rocky mountains alberta is used to demonstrate this four karst springs one perennial the remainder intermittent in one group are considered to be the outlets to a number of conduits the oldest and largest of these is possibly choked by sediment and acts as a reservoir rather than a conduit while others convey overflow floods from the upper saskatchewan glacier the aquifer is of great antiquity but has been disrupted by glaciation the aquifer model developed is a simple hypothesis but provides a valuable

simple transport models for karst systems abstract tracer tests are useful field methods with a wide range of applications in karst aquifers the measured tracer breakthrough curve at a karst spring allows the estimation of the important transport properties of the karst system the breakthrough curve is typically characterized by a long tailing and a low tracer recovery that is not captured by the classical one dimensional advection dispersion model partitioning models are often used and require a large number of parameters in the present work simplified transport models are proposed to simulate the typical karst breakthrough curve the model setup consists of a karst conduit that is interacting laterally with the surrounding matrix the solute transport in both the conduit and matrix are governed by the one dimensional advection dispersion equation and the resulting mathematical model consists of a coupled system of differential equations the laplace transform method is used to derive the transport models for various flow and boundary conditions the models are in terms of four physically meaningful parameters that represent the advection and dispersion properties of the flow in the conduit and matrix algebraic relationships to estimate the model parameters are also derived in terms of the key features of the breakthrough curves the main advantage of the proposed models are their simple formulation and ability to capture the long tailing of the breakthrough curve in terms of just a few parameters application of the models to two real karst aquifers demonstrate their effectiveness in simulating the observed breakthrough curves and estimating the key transport parameters

geomorphology of the post caldera monogenetic volcanoes at deception island antarctica implications for landform recognition and volcanic hazard assessment abstract deception island is one of the most active volcanoes in antarctica with more than 20 monogenetic eruptions during the holocene the latest episodes of 1967 1969 and 1970 have shown that volcanic activity on deception island can become a concern for tourists scientists and military personnel working on or near the island the objective of this work is to identify eruptive processes and the geomorphic evolution of post caldera monogenetic volcanic edifices at deception island by morphometric analyses supported by field observations morphometric analysis has been used since the 1970s to analyse scoria cones but it has rarely been applied to other monogenetic volcanoes such as tuff cones and tuff rings tuff cones and tuff rings represent the most common landforms during deception island s recent geological past with over 70 scattered eruptive vents inside and along the caldera rim these volcanic landforms have been studied based on field observations and later digital elevation model analyses their geometry ranges from 10 to 100 m in height and diameters vary between 300 and 2500 m the morphometric data suggest that tuff cones have a more circular crater than tuff rings with a significant separation between the two landforms using the height hco and basal width wco parameters tuff cones have hco wco ratios with values between 0 04 and 0 16 and outer slopes between 7 and 34 tuff rings have lower hco wco ratios that are between 0 01 and 0 04 and lower outer slopes between 3 and 21 this study shows that basic shape parameters in combination with slope angle analysis can be used to discriminate among different types of monogenetic volcanoes the initial eruptive related morphometric diversity however prevents correlation of eruption ages with morphometric parameters or constructing a relative chronology of the monogenetic eruptions this work provides a better comprehension of the potential evolution of a future eruption and a broader understanding of volcanic hazards on deception island

visualization of conduit matrix conductivity differences in a karst aquifer using time lapse electrical resistivity 1 in the karstic upper floridan aquifer surface water flows into conduits of the groundwater system and may exchange with water in the aquifer matrix this exchange has been hypothesized to occur based on differences in discharge at the santa fe river sink rise system north central florida but has yet to be visualized using any geophysical techniques using electrical resistivity tomography we conducted a time lapse study at two locations with mapped conduits connecting the santa fe river sink to the santa fe river rise to study changes of electrical conductivity during times of varying discharge over a six week period our results show conductivity differences between matrix conduit changes in resistivity occurring through time at the locations of mapped karst conduits and changes in electrical conductivity during rainfall infiltration these observations provide insight into time scales and matrix conduit conductivity differences illustrating how surface water flow recharged to conduits may flow in a groundwater system in a karst aquifer

dissolution in a variably confined carbonate platform effects of allogenic runoff hydraulic damming of groundwater inputs and surface groundwater exchange at the basin scale in variably confined carbonate platforms impermeable confining units collect rainfall over large areas and deliver runoff to rivers or conduits in unconfined portions of platforms runoff can increase river stage or conduit heads in unconfined portions of platforms faster than local infiltration of rainfall can increase groundwater heads causing hydraulic gradients between rivers conduits and the aquifer to reverse gradient reversals cause flood waters to flow from rivers and conduits into the aquifer where they can dissolve limestone previous work on impacts of gradient reversals on dissolution has primarily emphasized individual caves and little research has been conducted at basin scales to address this gap in knowledge we used legacy data to assess how a gradient of aquifer confinement across the suwannee river basin north central florida affected locations magnitudes and processes of dissolution during 2005 2007 a period with extreme ranges of discharge during intense rain events runoff from the confining unit increased river stage above groundwater heads in unconfined portions of the platform hydraulically damming inputs of groundwater along a 200 km reach of river hydraulic damming allowed allogenic runoff with sical 4 to fill the entire river channel and flow into the aquifer via reversing springs storage of runoff in the aquifer decreased peak river discharges downstream and contributed to dissolution within the aquifer temporary storage of allogenic runoff in karst aquifers represents hyporheic exchange at a scale that is larger than found in streams flowing over non karst aquifers because conduits in karst aquifers extend the area available for exchange beyond river beds deep into aquifers post depositional porosity in variably confined carbonate platforms should thus be enhanced along rivers that originate on confining units this distribution should be considered in models of porosity distribution used to manage water and hydrocarbon resources in carbonate rocks copyright 2013 john wiley sons ltd

mapping of an ophiolite complex by high resolution visible infrared spectrometry the sumail massif of the oman peridotite has been surveyed by the high spectral resolution imager hymap the field measurements have been taken simultaneously to the hymap campaign with a ger 3700 spectrometer to compare the two data sets further calibration and atmospheric correction are made through empirical line corrections a continuum removal by a modified gaussian model on reflectance is then performed for each pixel to minimize atmospheric scattering and shadowing effects classification from spectral distance is established using field observations and comparisons at full spectral resolution to identify peridotite subunits harzburgites and dunites and to distinguish plagioclase wehrlites from gabbros detections of hydrothermal transformations of olivine in serpentines and their alteration in carbonates along fracture networks characterized by narrow spectral signatures validate the classification this demonstrates the utility of the high spectral resolution and the development of appropriate processing methods for geological identifications

analyzing multi scale hydrodynamic processes in karst with a coupled conceptual modeling and signal decomposition approach abstract more than 25 of the world s population either lives on or obtains its water from karst aquifers which makes the understanding of these systems essential for water resources management however it is often difficult to observe and assess their internal dynamics precisely in this study we investigated 1 the ability of both conceptual model approach and signal decomposition methods to extract meaningful components from karst spring hydrographs and 2 how a modelled spring discharge acquires its spectral signature through a conceptual reservoirs model we used the conceptual modeling software karstmod to model the discharge of a small karst spring in normandy france we compared the model internal discharges with natural tracers of the system conductivity turbidity and piezometry the results suggested that the conceptual model was able to reproduce part of the internal hydrological behavior of the karst system especially the exchange dynamics between conduits and the surrounding aquifer we compared the internal flows of the model with wavelet details obtained from multiresolution analysis of the spring discharge these internal flows appeared strongly correlated to specific consecutive sums of wavelet details finally we studied how the modeled discharge at the spring was acquiring its spectral characteristics across the model using fourier spectra analysis cut off frequencies visible on the fourier spectrum of the spring were matching the frequencies obtained with the multiresolution analysis these results combined illustrate the ability of decomposition methods to reproduce the spectral variations of the different discharges within the model and likely within the observed karst system

chemical and isotopic δ18o δ2h δ13c 222rn multi tracing for groundwater conceptual model of carbonate aquifer gran sasso infn underground laboratory central italy summary a hydrochemical and isotope study was conducted on the drainage waters of an underground laboratory located inside the gran sasso massif central italy the study was expected to improve the conceptual model of groundwater circulation at the base of an over 1000 thick unsaturated zone in the gran sasso partitioned karst aquifer this lithostratigraphically and tectonically complex aquifer is typical of africa europe thrust and fold collision belt in the mediterranean area in this case investigations on water rock interactions during recharge in complex aquifers overlaid by a thick unsaturated zone have been made thanks to the strategic location of the gran sasso underground laboratories located in the core of a huge carbonate aquifer knowledge of the local basic hydrogeological setting was the starting point for a detailed hydrogeochemical and isotopic study which was carried out at the aquifer scale and at the fine scale in the underground laboratories the water rock interaction processes were investigated both spatially and in temporal sequences analysing recharge waters and groundwater in the underground laboratories by multitracing techniques including major ions and 18o 2h and 13c stable isotopes use of 222rn provides information on transit time in the aquifer processes proved to be typical of carbonate rocks with clear influence of vertical movement of water on chemical physical parameters through the unsaturated zone conversely in the saturated zone these processes proved to be dominantly affected by local geological structural conditions a conceptual model with dual flow velocity is proposed directly related to the local geological structural setting 222rn decay enables to calculate an effective velocity of around 10 m day for the fracture network through the sequence of less permeable dolomites and underlying limestone lag time between recharge and chemical changes in the saturated zone testifies to an effective velocity of about 35 m day for fast flow through recent and active extensional faults

trace metal cycling in karst aquifers subject to periodic river water intrusion abstract river water that enters critical zone aquifers can deliver metals and alter groundwater redox potential resulting in precipitation and or dissolution of metal oxides these effects on metal concentrations should be particularly dynamic in karst critical zones where surface water and groundwater are linked through preferential flow paths e g caves and conduits metals can be either toxins or micronutrients and thus their concentrations are important to water quality to evaluate trace metal dynamics in karst critical zones we measured pb and sr isotopic ratios and major and trace metal concentrations of fe mn oxide deposits collected from two water filled cave networks madison blue and peacock springs in the carbonate upper floridan aquifer florida usa we also measured dissolved and total metal concentrations in water from conduits of both cave networks during three river water intrusion events and subsequent flood recessions the fe mn oxides contain anthropogenic pb that increases in concentration from interior to exterior of the oxides indicating they formed and continued to grow over the past several decades sr isotope ratios of the fe mn oxides are intermediate between flood water and groundwater values and indicate they form during intrusion events this result is corroborated by variations in fe and mn concentrations in water during intrusion and recession the fe mn oxide interiors are more altered than exteriors as shown by depletion of mn concentrations and the lack of a positive ce anomaly in the interior of the fe mn oxides most trace metal concentrations correlate with mn concentrations suggesting remobilization of trace metals over time periods longer than individual intrusion events cycling between accumulation and dissolution of fe mn oxides presents challenges for evaluation and remediation of trace metal contamination of carbonate critical zones

flow parameters in a shallow conduit flow carbonate aquifer inner bluegrass karst region kentucky usa abstract in the carbonate aquifers which underlie most karst terrains groundwater flow is through a dendritic system of solution conduits in such aquifers termed shallow conduit flow aquifers the methods used to model granular and fracture aquifers are not generally applicable investigations were conducted in the inner bluegrass karst region of central kentucky with the objective of developing methods of modeling shallow conduit flow aquifers as well as obtaining quantitative information on a specific portion of the aquifer to assist in its management for water supply purposes in the inner bluegrass karst region groundwater basins are developed in each of which there is an integrated system of solution conduits which conducts recharge to a major spring one of the largest of these groundwater basins feeds royal spring which serves as the principal water supply for the town of georgetown the basin extends over 15 km to the southeast and most of its flow is furnished by underground diversions of cane run a surface stream with headwaters near the center of the city of lexington the principal objectives of the field investigation were to determine discharges at the spring and travel times to the spring from discrete recharge points within the basin termed swallets the spring is ungaged and an attempt was made to obtain a continuous discharge record by the dilution of dye introduced at a swallet comparison of the dye dilution discharge record with stage discharges at the spring revealed substantial discrepancies which are believed to be caused by as much as five sixths of the low flow discharge from the upper portion of the basin bypassing the spring the dye dilution method therefore provided significant insights into the geometry of the conduit system of the groundwater basin although it proved unsatisfactory as a method of determining discharges at the spring analysis of the travel times and stage discharges provided information on the conduit geometry by modeling the flow as open channel flow in a rectangular channel flow in the system is rapid ranging from 140 to 590 m h 1 although the flow rate increases with discharge the relationship is not simple owing to substantial increases in conduit cross sectional area at higher discharges flow is turbulent and subcritical under all conditions the most surprising result was the very low depth of flow calculated less than 17 cm at even the highest discharge although this must be considered an equivalent depth it is believed to indicate that active flow in shallow conduit flow aquifers is generally in a thin zone just beneath the water table

time variant cross correlation to assess residence time of water and implication for hydraulics of a sink rise karst system 1 transport rates and residence time in the subsurface are critical parameters for understanding water rock interactions for efficient contaminant remediation this paper presents a methodology for assessing flow and transit time of water through hydrological systems with specific applications to karst systems and implication for hydraulics of a conduit system surrounded by a porous and permeable intergranular matrix a time variant cross correlation function analysis is applied to bivariate time series that characterize mass transfer assuming a stationary system using sliding windows of various sizes we apply the method to 1 year long temperature records in the santa fe river north central florida measured at 1 the river sink where all the incoming surface water drains into a sinkhole 2 sweetwater lake where the river resurges into a 500 m long karst window and 3 the river rise where the water discharges from a first magnitude karst spring results are compared with those obtained using specific conductivity estimated residence time ranges from less than 1 day during floods to more than 15 days during base flow within the 8000 m flow path between the river sink and the river rise results are used to characterize geometric hydraulic and hydrodynamic properties of this sink rise system with strong matrix conduit interactions these properties are critical to the chemical and physical behavior of surface water groundwater mixing our results also have direct implications for sampling strategies and hydrograph separation of many karst systems with different degrees and types of matrix porosity and permeability

the influence of magma plumbing complexity on monogenetic eruptions jeju island korea terra nova 23 70 75 2011 abstract continuous pyroclastic successions from monogenetic volcanoes in the jeju island volcanic field korea were targeted for detailed geochemical investigations of juvenile ejecta to show that multiple distinct magma pulses may be erupted during a single monogenetic eruption deeply derived and possibly multiply sourced evolving magma pulses may erupt sequentially from the same vent and form generally uninterrupted depositional sequences with continuous chemical trends alternatively pulses can rise independently resulting in breccia horizons and truncation surfaces in depositional sequences and in stepped and mixed chemical trends we infer that uninterrupted eruptions result from clear plumbing systems in which a single large dyke system feeds an eruption and where differently sourced magmas are erupted independently congested plumbing systems consisting of dyke complexes give rise to vent shifts asymmetrical eruptive centres and composite depositional sequences integration of chemical variation and eruptive dynamics provides a powerful means of understanding monogenetic volcanoes

historic hydrovolcanism at deception island antarctica implications for eruption hazards deception island antarctica is the southernmost island of the south shetland archipelago in the south atlantic volcanic activity since the eighteenth century along with the latest volcanic unrest episodes in the twentieth and twenty first centuries demonstrates that the volcanic system is still active and that future eruptions are likely despite its remote location the south shetland islands are an important touristic destination during the austral summer in addition they host several research stations and three summer field camps deception island is characterised by a quaternary caldera system with a post caldera succession and is considered to be part of an active dispersed monogenetic volcanic field historical post caldera volcanism on deception island involves monogenetic small volume vei 2 3 eruptions such forming cones and various types of hydrovolcanic edifices the scientific stations on the island were destroyed or severely damaged during the eruptions in 1967 1969 and 1970 mainly due to explosive activity triggered by the interaction of rising or erupting magma with surface water shallow groundwater and ice we conducted a detailed revision field petrology and geochemistry of the historical hydrovolcanic post caldera eruptions of deception island with the aim to understand the dynamics of magma water interaction as well as characterise the most likely eruptive scenarios from future eruptions we specifically focused on the crimson hill estimated age between 1825 and 1829 and kroner lake estimated age between 1829 and 1912 eruptions and 1967 1969 and 1970 events by describing the eruption mechanisms related to the island s hydrovolcanic activity data suggest that the main hazards posed by volcanism on the island are due to fallout ballistic blocks and bombs and subordinate dilute pdcs in addition deception island can be divided into five areas of expected activity due to magma water interaction providing additional data for correct hazard assessment on the island

remote sensing for mineral exploration abstract remote sensing is the science of acquiring processing and interpreting images and related data acquired from aircraft and satellites that record the interaction between matter and electromagnetic energy remote sensing images are used for mineral exploration in two applications 1 map geology and the faults and fractures that localize ore deposits 2 recognize hydrothermally altered rocks by their spectral signatures landsat thematic mapper tm satellite images are widely used to interpret both structure and hydrothermal alteration digitally processed tm ratio images can identify two assemblages of hydrothermal alteration minerals iron minerals and clays plus alunite in northern chile tm ratio images defined the prospects that are now major copper deposits at collahuasi and ujina hyperspectral imaging systems can identify individual species of iron and clay minerals which can provide details of hydrothermal zoning silicification which is an important indicator of hydrothermal alteration is not recognizable on tm and hyperspectral images quartz has no diagnostic spectral features in the visible and reflected ir wavelengths recorded by these systems variations in silica content are recognizable in multispectral thermal ir images which is a promising topic for research

influence of partial confinement and holocene river formation on groundwater flow and dissolution in the florida carbonate platform much of what is known about groundwater circulation and geochemical evolution in carbonate platforms is based on platforms that are fully confined or unconfined much less is known about groundwater flow paths and geochemical evolution in partially confined platforms particularly those supporting surface water in north central florida sea level rise and a transition to a wetter climate during the holocene formed rivers in unconfined portions of the florida carbonate platform focusing on data from the santa fe river basin we show river formation has led to important differences in the hydrological and geochemical evolution of the santa fe river basin relative to fully confined or unconfined platforms runoff from the siliciclastic confining layer drove river incision and created topographic relief reorienting the termination of local and regional groundwater flow paths from the coast to the rivers in unconfined portions of the platform the most chemically evolved groundwater occurs at the end of the longest and deepest flow paths which discharge near the center of the platform because of incision of the santa fe river at the edge of the confining unit this pattern of discharge of mineralized water differs from fully confined or unconfined platforms where discharge of the most mineralized water occurs at the coast mineralized water flowing into the santa fe river is diluted by less evolved water derived from shorter shallower flow paths that discharge to the river downstream formation of rivers shortens flow path lengths thereby decreasing groundwater residence times and allowing freshwater to discharge more quickly to the oceans in the newly formed rivers than in platforms that lack rivers similar dynamic changes to groundwater systems should be expected to occur in the future as climate change and sea level rise develop surface water on other carbonate platforms and low lying coastal aquifer systems copyright 2012 john wiley sons ltd

modelling spring discharge and solute transport in conduits by coupling cfpv2 to an epikarst reservoir for a karst aquifer abstract karst aquifers differ from unconsolidated granular aquifers with respect to their groundwater flow behavior because of the dual permeability characteristics discrete conduit network coupled to a fissured matrix the duality of recharge point vs diffuse recharge as well as the duality of flow laminar vs turbulent state in many karst aquifers the epikarst frequently plays an important role in redistributing precipitation as diffuse recharge into the fissured matrix and as point recharge into the conduit network as well as for the temporal distribution of recharge input in this paper a coupled groundwater model ce cfpv2 erch is developed consisting of a combination of a simple reservoir model generating the recharge source function assuming the concept of an epikarst horizon erch with cfpv2 a discrete conduit continuum groundwater flow model of the phreatic karst aquifer the ce model is applied to simulate spring discharge and a tracer breakthrough in a karst aquifer near guilin city in southwest china in order to examine the effect of an added epikarst reservoir model simulations are carried out with cfpv2 but without including erch simulation results of both spring hydrograph and tracer breakthrough indicate that cfpv2 with erch performs much better a sensitivity analysis of the ce reveals the relative importance of parameters characterizing the epikarst reservoir point recharge is a main factor determining the large variation in spring discharge and its proportion to total recharge can reach 58 these simulation results highlight the importance of the temporal and spatial distribution of recharge to karst spring discharge response the coupled model provides an effective approach to include the effect of an epikarst zone in cfpv2 and it can easily be applied for the simulation of karst aquifers with similar characteristics as the study site

phreatomagmatic eruptions through unconsolidated coastal plain sequences maungataketake auckland volcanic field new zealand abstract maungataketake is a monogenetic basaltic volcano formed at 85 89 ka in the southern part of the auckland volcanic field avf new zealand it comprises a basal 1100 m diameter tuff ring with a central scoria spatter cone and lava flows the tuff ring was formed under hydrogeological and geographic conditions very similar to the present the tuff records numerous density stratified wet base surges that radiated outward up to 1 km decelerating rapidly and becoming less turbulent with distance the pyroclastic units dominantly comprise fine grained expelled grains from various sedimentary deposits beneath the volcano mixed with a minor component of juvenile pyroclasts 35 vol subtle lateral changes relate to deceleration with distance and vertical transformations are minor pointing to stable explosion depths and conditions with gradual transitions between units and no evidence for eruptive pauses this volcano formed within and on 60 m thick plio pleistocene poorly consolidated highly permeable shelly sands and silts kaawa formation capped by near impermeable water saturated muds tauranga group these sediments rest on moderately consolidated miocene aged permeable turbiditic sandstones and siltstones waitemata group magma water fuelled thermohydraulic explosions remained in the shallow sedimentary layers excavating fine grained sediments without brittle fragmentation required on the whole the resulting cool wet pyroclastic density currents were of low energy the unconsolidated shallow sediments deformed to accommodate rapidly rising magma leading to development of complex sill like bodies and a range of magma water contact conditions at any time the weak saturated sediments were also readily liquefied to provide an enduring supply of water and fine sediment to the explosion loci changes in magma flux and or subsequent stabilisation of the conduit area by a lava ring barrier led to ensuing strombolian and fire fountaining eruption phases future eruptions in littoral environments around auckland are likely to be of this type producing base surges that rapidly decrease in energy over short runout distances 1 km

storm response of the karstic carbonate aquifer of southcentral kentucky abstract temperature and specific conductance were continuously measured in the downstream drainage of the turnhole spring subbasin in the southcentral kentucky karst precipitation was monitored with a rain gage network in the catchment area so that the storm response of specific conductance and temperature could be examined the aquifer feeding the turnhole spring is highly karstic with much of the discharge through integrated open conduits some of which carry water from surface sinking stream catchments both temperature and specific conductance fluctuate rapidly in response to storm events the conductivity curves and to a lesser extent the temperature curves show a sharp dip that lags some hours behind the storm pulse at the onset of the dip is a complicated sequence of fine structures that is interpreted to be the inputs from conduit tributaries to the master trunk drainage system the recovery curves have an exponential form that can be fitted to produce a characteristic response time for the conduit system

river reversals into karst springs a model for cave enlargement in eogenetic karst aquifers most conceptual models of epigenic conduit development assume that conduits sourcing karst springs form as water that is undersaturated with respect to carbonate minerals flows from recharge to discharge points this process is not possible in springs fed by distributed recharge that is transmitted through aquifer matrix porosity such as unconfined aquifers in eogenetic carbonate rocks diffusely recharged water has a long residence time within the aquifer and thus would have equilibrated with the aquifer rocks prior to discharge to the conduits the upper floridan aquifer has high matrix permeability 10 13 m 2 and many springs lack discrete inputs of undersaturated allogenic water in their recharge areas consequently another explanation for their development is necessary during flooding of the suwannee river in north central florida water highly undersaturated with respect to carbonate minerals commonly recharges the upper floridan aquifer through spring vents and solution scallops oriented away from the vents suggest most dissolution along conduit walls occurs during these flow reversals during a single flow reversal at the peacock spring cave system flood water was capable of dissolving up to 3 4 mm of the conduit wall rock dissolution occurs as flow reversals follow preexisting features that include joints and paleo water table caves lack of speleothems in conduits in the upper floridan aquifer has been used as evidence that the caves formed in the phreatic zone however flooding would dissolve any speleothems that may have formed during previous subaerial exposure conduit enlargement during flow reversals suggests that dissolution can progress in the normal upstream directions and this process may be an important driver of dissolution in any karst aquifer with outflows to surface water that are subject to flooding flow reversals would also introduce dissolved organic carbon and oxygen into the groundwater and provide important energy sources for cave ecosystems as well as altering redox chemistry of the aquifer water

compound maar crater and co eruptive scoria cone in the lunar crater volcanic field nevada usa abstract bea s crater lunar crater volcanic field nevada usa consists of two coalesced maar craters with diameters of 440 m and 1050 m combined with a co eruptive scoria cone that straddles the northeast rim of the larger crater the two craters and the cone form an alignment that parallels many local and regional structures such as normal faults and is interpreted to represent the orientation of the feeder dyke near the surface the maar formed among a dense cluster of scoria cones the cone cluster topography resulted in crater rim that has a variable elevation these older cones are composed of variably welded agglomerate and scoria with differing competence that subsequently affected the shape of bea s crater tephra ring deposits associated with phreatomagmatic maar forming eruptions are rich in basaltic lithics derived from

investigation of karstic hydrological processes of niangziguan springs north china using wavelet analysis niangziguan spring complex is the largest karst spring in north china we investigate the karst hydrological processes by using morlet wavelet transform analysis and cross wavelet analysis based on monthly precipitation from 1958 to 2010 and spring discharge from 1958 to 2009 from morlet wavelet transform coefficients of precipitation and the spring discharge in niangziguan springs basin we find that the precipitation and discharge are characterized by the multi scale features in the time domain and the energy distribution of the signal is highly irregular across scales although precipitation eventually becomes spring discharge by infiltrating and propagating through karst formations the signals are attenuated the results also show that the precipitation of niangziguan springs basin has the main periodic components of 1 5 12 and 17 year periods with alternating wet drought cycle similarly the spring discharge of niangziguan springs has the main components of 17 year periods but the 1 5 and 12 year periodicity of precipitation are not reflected in spring discharge which is filtered by the aquifers the results of cross wavelet analysis reveal that the precipitation and spring discharge share the common periodicity of 17 years this means that those signals with high energy and long timescales can penetrate through the aquifer and be reflected in spring discharge whereas other signals are filtered and modified copyright 2011 john wiley sons ltd

vadose co2 gas drives dissolution at water tables in eogenetic karst aquifers more than mixing dissolution most models of cave formation in limestone that remains near its depositional environment and has not been deeply buried i e eogenetic limestone invoke dissolution from mixing of waters that have different ionic strengths or have equilibrated with calcite at different pco2 values in eogenetic karst aquifers lacking saline water mixing of vadose and phreatic waters is thought to form caves we show here calcite dissolution in a cave in eogenetic limestone occurred due to increases in vadose co2 gas concentrations and subsequent dissolution of co2 into groundwater not by mixing dissolution we collected high resolution time series measurements 1 year of specific conductivity spc temperature meteorological data and synoptic water chemical composition from a water table cave in central florida briar cave we found spc pco2 and calcite undersaturation increased through late summer when briar cave experienced little ventilation by outside air and decreased through winter when increased ventilation lowered cave co2 g concentrations we hypothesize dissolution occurred when water flowed from aquifer regions with low pco2 into the cave which had elevated pco2 elevated pco2 would be promoted by fractures connecting the soil to the water table simple geochemical models demonstrate that changes in pco2 of less than 1 along flow paths are an order of magnitude more efficient at dissolving limestone than mixing of vadose and phreatic water we conclude that spatially or temporally variable vadose co2 g concentrations are responsible for cave formation because mixing is too slow to generate observed cave sizes in the time available for formation while this study emphasized dissolution gas exchange between the atmosphere and karst aquifer vadose zones that is facilitated by conduits likely exerts important controls on other geochemical processes in limestone critical zones by transporting oxygen deep into vadose zones creating redox boundaries that would not exist in the absence of caves copyright 2014 john wiley sons ltd