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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That speleogenesis is although the term literally means the birth, origin or mode of formation of caves, the full extent of speleogenesis includes all the changes that take place between the inception and the eventual destruction of an underground drainage system. it includes development phases during which the active drainage voids are too small to be considered caves as normally defined, as well as phases when the cave no longer functions as a drain, is enlarging only by collapse and, eventually, is being totally removed [9].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for submarine (Keyword) returned 65 results for the whole karstbase:
Showing 16 to 30 of 65
Scuba observations of standstill levels in Elba Island (ltaly) and in Marie-Galante (West Indies). A worldwide sequence?, 1999, Collinagirard J,
Scuba observations (0 to -60 m) in Provence and Corsica and new data from Elba Island (Italy) indicate the bathymetric location of eustatic erosion levels in the Mediterranean Sea. A general sketch is given (standstill levels at-ii m, -17 m, -25 m, -35 m, -45 m, -50 m/55 m, -100 m). Isotopic data suggest contemporaneity of -100 m and -55 m levels with the two slow-down phases of Holocene transgression documented in Barbados and Tahiti coring (MWP-1A and 1B). Transgression acceleration after 14 000 BP explains the conservation of these littoral morphologies. Tectonics or isostasic movements (never more than 5 m) are prooved by differences observed in different areas of the world

Volcanic gaps and subaerial records of palaeo-sea-levels on Flores Island (Azores): tectonic and morphological implications, 1999, Azevedo Jmm, Ferreira Mrp,
The morphological evolution of Flores Island, as commonly observed for volcanic islands, suggests (1) the balance between constructive processes (effusive and moderately explosive volcanic activities and tectonic uplifting movements) and destructive processes (marine abrasion, stream erosion, crater-forming volcanic explosions, caldera collapses and tectonic subsidence) and (2) the recurrent fluctuations of the sea-level. Records of (a) gaps in the volcanic activity and (b) erosional and depositional marine activity are shown as: - epiclastic deposits of marine origin - erosional morphologies, such as abrasion platforms, terraces, cliffs and caves - intensive palagonitization of the volcanic rocks - vertical changes of the structures in the hydroclastic submarine formations. Taking into account (1) the vertical crustal movements (uplift and subsidence) which may occur in volcanic domains and (2) the sequence of regressive-transgressive trends in the relative sea-level as expressed by indicators of pale-sea-levels, it is assumed that the morphological evolution of Flores Island comprehends three main stages, The existence of important differences between the present-day altitudes of correlated marine records noted in Flores, in Santa Marie Island (Azores Archipelago) and Porto Santo Island (Madeira Archipelago) is related with their crustal behaviour and different volcanic and tectonic evolution.

Some geological observations in Slovačka jama cave (-1268m) in Velebit mountain, Croatia, 1999, Lacković, Damir, Š, Mida Branislav, Horvatinč, Ić, Nada, Tibljaš, Darko

During three speleological expeditions the Slovačka jama cave has been explored to the depth of 1268m. In the cave there are several channels with phreatic forms. The highest relict phreatic channel is probably due to sinkholes formed on the karst uvala Veliki Lubenovac at the time of uvala formation. Lower, recent and subrecent, phreatic horizons at the cave bottom are probably a part of the underground route of the Lika river which sinks on the north-eastern side of Velebit mountain and flows through the mountain to the submarine springs in the Adriatic sea. Other channels are mostly shafts and channels with meandering vadose forms. 14C isotope analysis of speleothems shows that the oldest are situated in both ancient and subrecent phreatic channels, while younger ones are found in the vadose meandering channel.


Submarine karst belt rimming the continental slope in the Straits of Florida, 2000, Land L. A. , Paull C. K. ,

Upper Quaternary water level history and sedimentation in the northwestern Black Sea, 2000, Winguth C. , Wong H. K. , Panin N. , Dinu C. , Georgescu P. , Ungureanu G. , Krugliakov V. V. , Podshuveit V. ,
A regional water level curve for the northwestern Black Sea covering lowstands of the past 900 ka has been inferred from shelf terraces and coastal onlaps identified in seismic data. Corrections for sediment compaction, isostatic response to sediment load and thermal subsidence were included. A water level lowstand of -151 m was found for the last glaciation, ca 30 m lower than the global sea level stand at the Last Glacial Maximum. Water level could develop independently in the Black Sea due to its isolation from the global oceans when the water level of the Black Sea was lower than its outlet.In addition, a deepsea fan complex in the northwestern Black Sea was investigated by seismic reflection, showing that it can be divided into the Danube fan and the Dniepr fan (also fed by the rivers Dniestr and Southern Bug). Eight seismic sequences were distinguished in the northwestern Black Sea and their thicknesses and facies distributions mapped. The two lowermost sequences consist mainly of unchannelized mass transport deposits (slumps, slides, debris flows), while the six upper sequences with their typical channel-levee systems as well as overbank and mass transport deposits constitute the deepsea fan complex. Correlation of fan development with the regional water level curve yields an inferred age of ca 900 ka BP for the Danube fan; development of the Dniepr fan started probably about 100 ka later. Computed average sedimentation rates range between 1.19 and 2.19 m/ka for the Danube fan and between 1.07 and 2.03 m/ka for the Dniepr fan. The corresponding rates for sediment accumulation are 68-141 t/a and 41-82 t/a. Mean denudation rates in the drainage area are computed to be 0.027-0.105 mm/a and 0.017-0.127 mm/a, respectively

Mn-Fe deposits in shallow cryptic marine environment: examples in northwestern Mediterranean submarine caves, 2001, Allouc J, Harmelin Jg,
Black coating of hard substrates by Mn and Fe oxides has long been reported from shallow, dark, submarine caves. However, these littoral metallic deposits have never been studied in detail, despite expected analogies with deep-sea polymetallic crusts. Submarine caves are characterized by darkness and low rates of exchanges with the open sea. Lack of primary production and confinement of inner water bodies result in marked oligotrophy and extremely reduced biomass, i.e. conditions close to those prevailing in deep-sea habitats. Field evidences suggested that the formation of Mn-Fe coatings was closely tied to these particular environmental conditions. The goal of this study was to examine the detailed features of Mn-Fe coatings from dark caves with different local conditions, and to try to identify the processes responsible for their deposition. Study sites and methods Three sublittoral, single-entrance, caves were sampled by scuba diving along the coasts of Provence (France, Mediterranean Sea) (fig. 1). The first site is a large karstic cave (Tremies Cave, 16 m depth at entrance floor, 60 m long; Marseille-Cassis area) with an ascending profile which results in a buffered thermal regime and markedly oligotrophic conditions due to warm water trapping in its upper part (fig. 1 and 2). Wall fragments were sampled at 30 m (medium confinement : zone B) and 60 in (strong confinement : zone C) from the cave entrance. The second site is a large tubular cavity open in conglomerate formations (3PP Cave, 15 m depth at entrance floor, 120 m long; La Ciotat) with a descending profile which results in relative permanence of winter temperatures within the inner parts, complex water circulation and presumed greater input of sedimented particles than in the preceding cave (fig.1 and 2). Wall samples were taken at 25 m, 70 in and 100 m from entrance. The third site is a small, horizontal, cave open in quartzite formations (Bagaud Cave, 7 in depth at entrance floor, about 10 m long; WNW of Port-Cros Island, bay of Hyeres). Sampling was performed on walls of a narrow corridor between an anterior room and a smaller inner room. A sporadic outflow of continental waters is located in the inner room. The samples were preserved in 50% ethylic alcohol or studied soon after their sampling. Before carbon coating and SEM examination, or microanalyses with SEM-associated spectrometers, they were treated in a 33% Chlorox solution and thereafter washed in demineralized water and dried. Micromorphology At low-medium magnification (<20,000), the aspect of coatings varies between caves and, especially, between inner-cave locations. All the described structures are made up of Mn and Fe oxides. In Tremies Cave, coatings of walls from zone B are composed of irregular erected constructions (height : 10s to 100s μm) formed by the aggregation of roughly ovoid primary concretions of about 10 μm (fig. 3). The surface of those primary concretions displays numerous lacunose to reticulate films (pores, about 0.5 μm in diameter, are often subrounded). Remnants of these films and organomorphic corpuscles occur also within the primary concretions (fig. 4). On younger substrates (broken wall exposed since 1970), primary concretions are poorly developed and no prominent construction is visible (fig. 5). In more confined conditions (zone C), the erected constructions of ancient coatings are smaller and less numerous than in zone B but are well individualized (fig. 6). In this zone: C, besides some remnants of lacunose to reticulate films (fig. 7), there is an appearance of filaments and ovoid corpuscles (height/width : 10-30/5-15 μm), which seem to be linked to filaments by a short stalk (fig. 8). In 3 PP Cave, at 25-70 m from entrance, wall coatings present porous heaps of primary concretions (fig. 9). The surface and the inside of the latter comprise remnants of lacunose to reticulate films that evoke those observed in Tremies Cave (fig. 10 and 11). On younger substrates (hard parts of sessile invertebrates), coatings are restricted to micrometric organomorphic corpuscles with some remnants of lacunose or fibrous films (fig. 12). At 100 in from the entrance, coatings are shaped by numerous erected constructions, more or less coalescing (fig. 13). Besides remnants of lacunose films, the primary concretions contain interlacing filaments (diameter : 0.2-0.3 μm) forming cords or veils (fig. 14). In Bagaud Cave, the primary concretions are aggregated in irregular heaps (fig. 15). Lacunose films are particularly frequent and tend to form three-dimensional mamillated structures that were not observed in the other caves (fig. 16). In particular, there is an appearance of tubular structures (fig. 17) and of numerous hemispheroidal structures (diameter : 4-5 μm) with an upper orifice (fig. 18 and 19). At higher magnification (20,000), whatever the cave and inner-cave location, the aspect of oxide deposits is rather smooth or, especially, microgranular (fig. 20). Mineral composition The composition of coatings is different between caves and according to their inner-cave location. In both large caves (Tremies and 3 PP), the Mn/Fe ratio increases with the distance from the cave entrance, i.e. when exchanges with the open sea diminish (fig. 21a). This trend is particularly clear in Tremies Cave, where the confinement gradient is strongly marked. Besides, the Mn/Fe ratio also seems to increase when films are present in the analysed volume (some cubic micrometers) (fig. 21b). In Bagaud Cave, the Mn/Fe ratio reaches high values despite the small size of this cave and its low confinement level. Discussion and conclusions SEM observations suggest that in each studied cave, the Mn-Fe coatings are biosedimentary deposits. Genesis of these deposits is assumed to result mainly from the replacement of biofilms (composed of cells and slime, i.e, of extracellular polymeric substance produced by microorganisms) generated by microbial populations colonizing the cave walls. Considering the darkness of the cave-locations, microbes consist mainly in bacteria, but fungi are probably responsible for the filaments and ovoids corpuscules (evoking sporocysts) occurring in innermost parts. Observations at different scales of the morphological features of oxide deposits reveal a structured organisation which varies along the strong environmental gradients (particularly the confinement level) that occur from the entrance to the innermost parts : erected constructions made up of primary concretions become more and more defined and acquire a pseudo-columnar shape. The aspect of biofilms appears to be controlled by the same environmental parameters. In open or relatively open environments, they frequently show a three-dimensional development (with frequent skullcape-like shapes), while in more confined conditions they exhibit a planar layout. These changes reflect either the adaptation of the slime-producing bacteria to the local trophic resources (correlated to the rate of exchange with the open sea) and water movements, or spatial replacement of taxa. It is assumed that slime (mainly composed of water and exopolysaccharides) induces a local increase of the concentration in dissolved Mn and acts as an ion exchange resin that allows the retention of Mn on the functional groups of EPS. These conditions promote the nucleation of Mn oxide crystallites in the slime. Then. the anionic character of Mn oxides in seawater, and their capacity to catalyse the oxydation of Mn2 to Mn4, allow the process to go on without any other biological intervention; thus, the process of crystal growth becomes possible. In caves where Mn is only supplied by seawater (Tremies and 3 PP), the average value of the Mn/Fe ratio of coatings is negatively correlated to the local availability of nutrients. This trend is probably linked to changes in the selectivity of slimes towards the processes of retention of cations, because this ratio is clearly influenced by the occurrence of biofilms. However, independently from trophic resources, the Mn/Fe ratio can be notably increased when additional Mn is provided by the seeping or flowing of continental waters (Bagaud Cave)

Water-upwelling pipes and soft-sediment-deformation structures in lower Pleistocene calcarenites (Salento, southern Italy), 2001, Massari F. , Ghibaudo G. , D'alessandro A. , Davaud E. ,
A thin sedimentary blanket, consisting mostly of subtidal, unconformity-bounded calcarenite units, was deposited in the small Novoli graben (Apulian foreland, southern Italy) in Pliocene-Pleistocene time. In a limited part of the study area the lower Pleistocene 'Calcarenite di Gravina,' forming the thicker part of this blanket, is crossed by continuous to discontinuous cylindrical pipes as much as 12 m high, most commonly consisting of stacked concave- upward laminae, locally grading upward into soft-sediment-deformation features and large dishes. The evidence favors an origin linked to upwelling of overpressured groundwater from a large karstic reservoir hosted in the Mesozoic carbonate rocks; the reservoir periodically developed a relatively high hydrostatic head due to Tertiary to Pleistocene cover acting as an aquitard or aquiclude. As a result, submarine springs were generated, the activity of which was primarily controlled by relative sea-level fluctuations. It is suggested that the pipes were located in those points where the hydrostatic pressure was sufficient to fluidize the overlying sediment and could be released without notably affecting the surrounding sediments. Some pipes cross calcarenitic infills of karstic sinkholes developed in the underlying units, whereas others follow the course of vertical to high-angle extensional synsedimentary tectonic fractures generated when the calcarenites were still in an unconsolidated to semiconsolidated state. The former relationships suggest that vertical routes of water upwelling during highstand of base level commonly coincided with axes of vadose solution during base-level lowstand; the latter suggest that opening of fractures enhanced the connection of the deep aquifer with the surface, hence intensifying water upwelling. We think that fluidization along the fractures was not hindered by the partially coherent state, and that pipes with a cylindrical geometry could form in spite of the planarity of the fractures. The formation of the pipes and their internal structure of stacked concave-upward laminae is thought to be consistent with a process of fluidization due to through-flowing waters. We believe that essential in this process is the role of upward-migrating transient water-filled cavities, akin to the voidage waves (Hassett's [1961a, 1961b] parvoids) experimentally reproduced by several authors in liquid fluidized beds, and regarded as true instability phenomena of a fluidized suspension occurring above minimum fluidization velocity. It is suggested that the process is akin to the production of the dish structure. It consists of the filling of transient, upward-migrating, water-filled cavities through steady fallout of particles from the cavity roof, their redeposition in a more consolidated state, and subsidence of the roof due to water seepage upward from the cavity. The process was accompanied by segregation of grains according to their size and density, as well by elutriation of finest particles, and led to a new pattern of sediment texture, packing, and fabric with respect to the surrounding calcarenites

Toward a coastal ground-water typology, 2001, Bokuniewicz H,
Although submarine ground-water discharge is recognised as being of physical and ecological significance, direct measurements are rare, and calculations are hampered by a lack of offshore data. Classification of the world's coast with respect to its potential, submarine ground-water contribution would help to focus attention on the most important areas and to extrapolate existing data. A classification may be based on relevant physical/climatological parameters (e.g. precipitation, soil type etc.), or geologic/geomorphic classes (e.g. karst, coastal plain, etc.), or on a collection of state parameters. State parameters for a coastal ground-water typology may include aquifer thickness, onshore hydraulic gradient, anisotropy and fractal dimension of the shoreline. Topographic gradient can serve as a surrogate for the hydraulic gradient. A fourth type of classification may be based on the distribution of salinity in the subterranean estuary but adequate subsurface data are not yet available. (C) 2001 Elsevier Science B.V. All rights reserved

Les karsts littoraux des Alpes-Maritimes : inventaire des mergences sous-marines et captage exprimental de Cabb, 2002, Gilli, ric
Inventory of coastal and submarine springs in the Alpes-Maritimes (France) - Experimental catchment at the Cabb spring. Several submarine freshwater springs are present on karst shore in the Alpes-Maritimes (France). Salinity and conductivity measuring coupled with GPS location has permitted to inventory these springs. Three main springs have an average flow around 500 l/s. A balance on inland and offshore springs allows to explain the deficit observed on karst units of Arc de Nice area. A dam was built in the submarine karst spring of Cabb Massolin (Roquebrune-Cap-Martin, France) to study the effects of an artificial augmentation of the pressure on the salinity of a karst aquifer. Trials in low and high water levels show the impossibility to increase the pressure. The presence of several springs and the important jointing of limestone dont allow a sufficient impermeability of the dam site. Nevertheless, the salinity decreases, due to the physical separation between the two kinds of water.

The sponge community in a semi-submerged temperate sea cave: Density, diversity and richness, 2002, Bell Jj,
The sponge communities inhabiting a temperate semi-submerged sea cave were investigated at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. Thirty-one species of sponge were reported, the majority of which exhibited either an encrusting or massive morphology. Sponge density (averaged over depth) increased with horizontal distance (5 m intervals) into the cave until approximately 30 m, corresponding to the maximum algal intrusion (algal information from Norton et al., 1971). Species diversity and richness (averaged over depth) were highest at 10 m horizontal distance from the cave entrance. Variability in sponge density, diversity and richness was observed with increasing vertical depth (0.5 m intervals) at most horizontal intervals sampled (5 m apart). These three variables increased initially with depth, but then decreased towards the seabed. Bray-Curtis Similarity Analysis and Multi-Dimensional Scaling (MDS) showed cave sponge community composition to have greater similarity (50%) with local loose rock habitats than the nearby cliffs. Similar processes structuring cave and loose rock sponge communities may account for this situation. Information collected from this and previous studies on the biotic (algal communities, other fauna and competition) and abiotic factors (water flow rate, depth, aerial exposure, light, cave morphology, nutrient depletion and humidity) affecting this and other caves is discussed with respect to its influence on the sponges inhabiting different parts of the cave. Although horizontal zonation patterns have been considered analogous to vertical distribution patterns for algal communities (due to similar decreases in light), this was not the case for the studied sponge communities

Coastal and submarine karstic discharges in theGokova Bay, SW Turkey, 2002, Bayari Cs, Kurttas T,
Hydrochemical, stable isotopic (18O and 2H) and thermal infrared data of LANDSAT 5 TM for sea surface temperature anomalies have been used to determine the extent and spatial variation of salinization in coastal and submarine karstic groundwater discharges in the Gokova Bay area, located in the SW Turkey. The bay is an active graben extending in an east-west direction. An artesian aquifer in the eastern tidal plain is the only source of fresh groundwater, whereas Tertiary and Mesozoic carbonates contacting with sea along the northern coastline provide abundant but saline water. Physical properties, major ion chemistry and stable isotope composition indicate a westward increase in the salinity of the karstic springs. The temporal variation of salinity in groundwater is either related to variations in sea level or in seasonal recharge rates, while some springs have time-invariant salinity. Submarine groundwater discharges were determined successfully from satellite images and verified by ground measurements of pH, temperature and electrical conductivity. Some of these discharges are also characterized by the existence of a halocline, as observed during Scuba diving. The westward-increasing salinity appears to be related to decreasing groundwater discharge in this direction

Submarine karst of Croatia - evidence of former lower sea levels, 2002, Surić, Maš, A

During the last, Late Pleistocene-Holocene transgression, rising sea flooded a vast part of the Dinaric karst. Due to prevalence of carbonate rocks in the drainage area of most of the rivers on Eastern Adriatic coast, those rivers carry only approximately 20% of particulates as suspended matter and the rest is dissolved. Consequently, many typical karst features such as karrens, dolines, poljes, caves, pits and river valleys and canyons as well, presently under the sea, can still be recognized. Beside these simply drowned features, some new ones were formed by the sea level rise. Those are submarine springs, so called vruljas, brackish coastal springs and marine lakes. The most significant evidences of former subaerial conditions are speleothems in submerged caves and calc tufa deposits of drowned paleo rivers. Both of them could be used for determination of the former low sea level stands.


Caves and Karsts of Northeast Africa., 2003, Halliday William R.
At least potentially karstifiable rocks cover much of the surface of Egypt and northern Libya. Study of caves and other karstic features of this region has been hampered by lack of roads, rapid disintegration of the surface of friable, poorly consolidated limestone, wind-blown sand and other factors. Interbedding with marly aquicludes hampers speleogenesis locally. Calcareous and evaporite karsts are present, however, and their waters are important albeit generally limited resources. Large quantities of fresh water are lost through submarine springs downslope from Libya's Gebel al Akhdar range; the caves and karst of that range may be among the world's greatest. A recent attempted compendium of caves and karsts of Egypt and Libya contains several important errors; the supposed 5+ km Ain Zayanah Cave does not exist and the Zayanah System includes several smaller caves. The Bir al Ghanam gypsum karst of northwest Libya, however, has caves up to 3.5 km long. In Egypt, the Mokattam, South Galala, Ma'aza, Siwa and Western Desert karsts and the "White Desert" chalk karst of Farafra Depression are especially important. Qattara and nearby depressions may be karstic rather than structural in origin. Unique Wadi Sannur Cave is the world's largest gour and a potential World Heritage site. Little knownsandstone karsts or pseudokarsts in southwestern Egypt may contain analogues of features recently identified on Mars. The well-publicised Uweinat caves of northwestern Sudan are talus caves.

The use of hydrochemical techniques to estimate the discharge of Ovacik submarine springs on the Mediterranean coast of Turkey, 2003, Elhatip H,

Geophysical evidence for karst formation associated with offshore groundwater transport: An example from North Carolina, 2003, Evans Rl,
Marine geophysical data from Long Bay, North Carolina, involving a novel combination of electromagnetic and high-resolution Chirp seismics, show evidence of submarine karst formation associated with what has been inferred to be a site of high-flux submarine groundwater discharge (SGD) a substantial distance offshore. Recently observed temperature and chemical signals from wells in this area provide the basis for the interpretation of the high-flux SGD here, and they also suggest a terrestrial source for the groundwater and thus a potentially important route for nutrient transport to the oceans. Our data indicate that karstification is localized to the high-flux zone, and we suggest that mixing of the chemically distinct (but saline) groundwater with seawater has resulted in the karstification. As karstification increases permeability and flux, a positive feedback would tend to progressively enhance submarine groundwater discharge. Our data reveal a significant local anomaly in apparent porosity: a dense block that may have initiated the local focusing of groundwater flow. Conditions favorable to the formation of similar locally punctuated sites of high-flux SGD are likely to exist along the mid to inner shelf of the southeastern United States, where carbonate aquifers are prevalent

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