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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. ...

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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. ...

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That injection head is a swivel head connector through which drilling fluid is injected into the drill pipe [16].?

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Your search for shelf (Keyword) returned 68 results for the whole karstbase:
Showing 16 to 30 of 68
Chapter 11 Southern Svalbard:Bjornoya and submarine geology, 1997, Harland W. Brian, Geddes Isobel, Doubleday Paul A. ,
The area south of Spitsbergen (about 76{degrees}31'N) to latitude 74{degrees}N, and between longitudes 10{degrees}E and 35{degrees}E, by which Svalbard was first defined, contains the small island of Bjornoya (Bear Island, Baren Insel) and the rest is sea (Fig. 11.1). The 500 m isobath conveniently separates the edge of the Barents shelf from the Norwegian Sea Basin which runs south from Spitsbergen between 14{degrees} and 16{degrees}30'E. To the east, the large shallow area, Spitsbergenbanken, less than 100 m deep, supports Bjornoya at its southwestern end, extends northeast to Hopen and joins Edge{degrees}ya. It is separated from Spitsbergen to the north by the Storfjordyrenna and to the east by Hopendjupet. These submarine valleys appear to drain westwards into the ocean deep with deltaic fronts convex westward. This chapter focuses first on Bjornoya which though small is a key outcrop in the Barents Sea and distinct in many respects from Spitsbergen being about 250 km distant. The chapter then surveys a little of what is known of the surrounding sub-sea area. Bjornoya (20 km N-S and 15 km E-W), as the southern outpost of Svalbard, has long been a key to Svalbard geology since it is generally free all year from tight sea ice. But though its location is convenient, its cliffs generally bar access. Indeed there are very few places where landing by other than inflatable dinghy are feasible. After the island had been claimed by a Norwegian syndicate in 1915 mining of Tournaisian coal began in 1916 and exported over 116000 ... This 250-word extract was created in the absence of an abstract

An abrupt drowning of the Black Sea shelf, 1997, Ryan William B. F. , Pitman I. I. I. , Major Candace O. , Shimkus Kazimieras, Moskalenko Vladamir, Jones Glenn A. , Dimitrov Petko, Gorur Naci, Sakinc Mehmet, Yuce Huseyin,
During latest Quaternary glaciation, the Black Sea became a giant freshwater lake. The surface of this lake drew down to levels more than 100 m below its outlet. When the Mediterranean rose to the Bosporus sill at 7,150 yr BP1, saltwater poured through this spillway to refill the lake and submerge, catastrophically, more than 100,000 km2 of its exposed continental shelf. The permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of Europe at that time

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

Mesozoic dissolution tectonics on the West Central Shelf, UK Central North Sea, 1999, Clark Ja, Cartwright Ja, Stewart Sa,
3-D seismic mapping of the Upper Jurassic Kimmeridge Clay Formation on the West Central Shelf in the Central North Sea reveals a complex fault array which is constrained by seismic interpretation and well control to be of late Jurassic/early Cretaceous age. Fault shapes in plan-view range from linear to circular. Linear fault lengths are 200-300 m to 5 km, the strongly curved and circular faults range in diameter from 100-1000 m. Fault trends are apparently random and display no correlation in location or trend with basement (sub-Zechstein) structures. There is, however, a strong link between this fault pattern and the structure of the top Zechstein (top salt) surface. Linear faults occur at the edges of elongate salt walls and the circular faults lie directly above structures which have been interpreted here as tall, steep-sided salt chimneys. The salt chimneys are present only in the thick, elongate minibasins of Triassic sediment which lie between the salt walls. It is argued that salt dissolution controls the timing, location, orientation and shape of the late Jurassic/early Cretaceous faults. A model is provided to account for the development of both salt walls and chimneys. We suggest that early Triassic karstification of the Zechstein evaporites led to development of an array of circular collapse features. During the ensuing episode of Triassic halokinesis which led to minibasin subsidence and salt wall growth, salt passively 'intruded' the circular collapse features within the subsiding minibasins to form narrow salt chimneys. The resulting array of salt walls and chimneys was subject to dissolution during subsequent subaerial exposure and the late Jurassic marine transgression of the basin (creating the observed fault array), prior to sealing of the salt from circulating groundwater by compaction of the Upper Jurassic and Lower Cretaceous shales which blanket the area. (C) 1999 Elsevier Science Ltd. All rights reserved

The last sea level changes in the Black Sea: evidence from the seismic data, 1999, Demirbag E, Gokasan E, Oktay Fy, Simsek M, Yuce H,
High resolution shallow seismic data collected from the southwestern shelf of the Black Sea indicate five different seismic stratigraphical units. The lower three of them belong to the Upper Cretaceous-Eocene, Oligocene-Miocene and Early Quaternary (prior to Holocene) sediments, respectively. These units are considered as a basement for the recent sediments deposited related to the latest connection of the Black Sea and the Mediterranean. The surface of these units are truncated to form an etchplain developed before the Flandrian transgression. The fourth unit covers the older units by an onlap. Its contact with the older units seen at -105 m is the shoreline of the Black Sea prior to the last major sea-level change. The fifth unit has been deposited since drowning of the Black Sea shelf. The principal cause of drowning of the Black Sea shelf is not only the last sea level rise as it is at the shelves of the Sea of Marmara but also the opening of the Strait of Istanbul. It is also realised by the comparison of the shelf area and the Catalca-Kocaeli etchplain that, the present continental part of this etchplain has been considerably uplifted with respect to the shelf area along the present shoreline. This uplifting must have also reactivated the faults around the Strait of Istanbul foundering the strait valley and, thus, permitting the Mediterranean waters to pass into the Black Sea, and initiating the sudden drowning of the Black Sea shelf

Bedrock Features of Lechuguilla Cave, Guadalup Mountains, New Mexico, 2000, Duchene, H. R.
Lechuguilla is a hypogenic cave dissolved in limestones and dolostones of the Capitan Reef Complex by sulfuric acid derived from oil and gas accumulations in the Delaware Basin of southeast New Mexico and west Texas. Most of the cave developed within the Seven Rivers and Capitan Formations, but a few high level passages penetrate the lower Yates Formation. The Queen and possibly Goat Seep formations are exposed only in the northernmost part of the cave below -215 m. Depositional and speleogenetic breccias are common in Lechuguilla. The cave also has many spectacular fossils that are indicators of depositional environments. Primary porosity in the Capitan and Seven Rivers Formations was a reservoir for water containing hydrogen sulfide, and a pathway for oxygenated meteoric water prior to and during sulfuric acid speleogenesis. Many passages at depths >250 m in Lechuguilla are in steeply dipping breccias that have a west-southwest orientation parallel to the strike of the shelf margin. The correlation between passage orientation and depositional strike suggests that stratigraphy controls these passages.

Drainage-basin-scale geomorphic analysis to determine reference conditions for ecologic restoration--Kissimmee River, Florida, 2000, Warne Andrew G. , Toth Louis A. , White William A. ,
Major controls on the retention, distribution, and discharge of surface water in the historic (precanal) Kissimmee drainage basin and river were investigated to determine reference conditions for ecosystem restoration. Precanal Kissimmee drainage-basin hydrology was largely controlled by landforms derived from relict, coastal ridge, lagoon, and shallow-shelf features; widespread carbonate solution depressions; and a poorly developed fluvial drainage network. Prior to channelization for flood control, the Kissimmee River was a very low gradient, moderately meandering river that flowed from Lake Kissimmee to Lake Okeechobee through the lower drainage basin. We infer that during normal wet seasons, river discharge rapidly exceeded Lake Okeechobee outflow capacity, and excess surface water backed up into the low-gradient Kissimmee River. This backwater effect induced bankfull and peak discharge early in the flood cycle and transformed the flood plain into a shallow aquatic system with both lacustrine and riverine characteristics. The large volumes of surface water retained in the lakes and wetlands of the upper basin maintained overbank flow conditions for several months after peak discharge. Analysis indicates that most of the geomorphic work on the channel and flood plain occurred during the frequently recurring extended periods of overbank discharge and that discharge volume may have been significant in determining channel dimensions. Comparison of hydrogeomorphic relationships with other river systems identified links between geomorphology and hydrology of the precanal Kissimmee River. However, drainage-basin and hydraulic geometry models derived solely from general populations of river systems may produce spurious reference conditions for restoration design criteria

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

Upper Miocene karst collapse structures of the east coast, Mallorca, Spain, 2000, Ardila Pedro Robledo, Pomar Luis

In the sea cliffs on the Mallorca Island, Western Mediterranean there are extensive outcrops of Upper Miocene carbonate rocks. On the Eastern coast of Mallorca, the reefal complex is overlain by a Messinian shallow-water carbonate complex. There are abundant Paleokarst collapse structures. The Santanyí Limestone beds are affected by V-incasion structures produced by roof collapse of caverns developed in the underlying reefal complex. According to the model, the origin of some of these karst-collapse structures may be related to early diagenetic processes controlled by high-frequency sea-level fluctuations. During lowstands of sea level, fresh-water flow might have create a cave system near the water table by dissolution of aragonite in the reef front facies and coral patches existing in the lagoonal beds. This cave system developed near the subaerial erosion surface. During subsequent rise of sea level inner-shelf beds overlaid the previously karstified reef-core and outer-lagoonal beds. Increase of loading by subsequent accretion of the shallow-water carbonates might have produced V-incasion structures by gravitational collapse of cave roofs when these beds were still not completely consolidated.


Sequence stratigraphy of the type Dinantian of Belgium and its correlation with northern France (Boulonnais, Avesnois), 2001, Hance L. , Poty E. , Devuyst F. X. ,
The relative influences of local tectonics and global eustasy in the architecture of the sedimentary units of the Namur-Dinant Basin (southern Belgium) are determined. Nine third-order sequences are recognised. During the Lower Tournaisian (Hastarian and lower Ivorian) a homoclinal ramp extended from southern Belgium through southern England (Mendips) and into southern Ireland. From the upper Ivorian to the lower Visean rapid facies changes occurred due to progradation and increasing prominence of Waulsortian mudmounds. Progradation gradually produced a situation in which inner shelf facies covered the Namur (NSA), Condroz (CSA) and southern Avesnes (ASA) sedimentation areas, whereas outer shelf facies were restricted to the Dinant sedimentation area (DSA). During the middle and late Viscan a broad shelf was established from western Germany to southern Ireland. Because the shelf built up mainly by aggradation, parasequences can be followed over a large area. An early phase of Variscan shortening is perceptible during the Livian. The stratigraphic gap between the first Namurian sediments (E2 Goniatite Zone) and the underlying Visean varies from place to place, but is more important in the north. Sequence 1 straddles the Devonian-Carboniferous boundary. It starts with a transgressive system tract (TST) corresponding to the Etroeungt Formation (Fm.) and its lateral equivalent (the upper part of the Comb lain-au-Pont Fin.), and to the lower member of the Hastiere Fin. The highstand system tract (HST) is represented by the middle member of the Hastiere Fin. which directly overlies Famennian silicielastics in the northern part of the NSA. Sequence 2 starts abruptly, in the DSA and CSA, with the upper member of the Hastiere Fin. as the TST. The maximum flooding surface (MFS) lies within the shales of the Pont d'Arcole Fin., whereas the thick-bedded crinoidal limestones of the Landelies Fm. form the HST. Sequence 3 can clearly be recognised in the DSA and CSA. Its TST is formed by the Maurenne Fm. and the Yvoir Fm. in the northern part of the DSA and by the Maurenne Fm. and the Bayard Fin. in the southern part of the DSA. The Ourthe Fin. represents the HST. Growth of the Waulsortian mudmounds started during the TST. Sequence 4 shows a significant change of architecture. The TST is represented by the Martinrive Fm. in the CSA and the lower part of the Leffe Fin. in the DSA. The HST is marked by the crinoidal rudstones of the Flemalle Member (Mbr.) and the overlying oolitic limestones of the Avins Mbr. (respectively lower and upper parts of the Longpre Fin.). These latter units prograded far southwards, producing a clinoform profile. Sequence 5 is only present in the DSA and in the Vise sedimentation area (VSA). The TST and the HST form most of the Sovet Fm. and its equivalents to the south, namely, the upper part of the Leffe Fm. and the overlying Molignee Fm. In the VSA, the HST is locally represented by massive grainstones. Sequence 6 filled the topographic irregularities inherited from previous sedimentation. In the CSA, NSA and ASA the TST is formed by the peritidal limestones of the Terwagne Fm. which rests abruptly on the underlying Avins Nibr. (sequence 4) with local karst development. In the DSA, the TST corresponds to the Salet Fin. and, further south, to the black limestones of the strongly diachronous Molignee Fin. Over the whole Namur-Dinant Basin, the sequence ends with the thick-bedded packstones and grainstones of the Neffe Frn. as the HST. Sequence 7 includes the Lives Fm. and the lower part of the Grands-Malades Fm. (Seilles Mbr. and its lateral equivalents), corresponding respectively to the TST and HST. Sequence 8 corresponds to the Bay-Bonnet Mbr. (TST), characterised by stromatolitic limestones. The HST corresponds to the Thon-Samson Mbr. Sequence 9 is the youngest sequence of the Belgian Dinantian in the CSA and DSA. It includes the Poilvache Nibr. (TST, Bonne Fm.) and the Anhee Fm. (HST). These units are composed of shallowing-upward parasequences. The uppermost Visean and basal Namurian are lacking in southern Belgium where sequence 9 is directly capped by Namurian E2 silicielastics. In the VSA, sequence 9 is well developed

Weichselian palaeoclimate and palaeoenvironment in Europe: background for palaeogroundwater formation, 2001, Vaikmae R. , Edmunds W. M. , Manzano M. ,
A review is given of palaeoclimatic and palaeoenvironmental evidence across Europe for the Weichselian period relevant to interpreting the emplacement and circulation of groundwaters. In addition, this provides the background against which the evidence of past climates and environments contained in groundwaters in coastal areas of Europe, from the Baltic to the Atlantic Ocean may be compared. For much of the Weichselian, although significantly colder than at present, conditions were favourable for the recharge of groundwater, as shown, for example, by periods of speleothem growth. During the last glacial maximum (LGM) recharge is likely to have ceased over much of permafrost-covered Europe, although shallow groundwater recharge from meltwater (generated by the geothermal gradients) could have taken place beneath the ice where pressure relief through tunnel valleys may have occurred. Modern recharge could have started as early as 13 14C ka BP, but probably interrupted by the Younger Dryas between 11 and 10 14C ka BP. In the Baltic areas, ice-dammed lakes inhibited the start of the modern hydrogeological regimes until c. 10.3 14C ka BP. Tundra conditions prevailed over most of ice-free southern Europe at the time of the LGM. At this time the area south of the Portuguese-Spanish border retained a generally warm and relatively humid climate due to the maintenance of warmer sea-surface temperatures derived from Atlantic Ocean circulation. For most of coastal Europe, however, the most significant impact on groundwater circulation is likely to have been the lowering of sea levels that drained large areas of the shelf, such as the North Sea and the English Channel, and also had a significant impact on the Atlantic coast of the Iberian Peninsula where the maximum lowering of up to 130 m would have been experienced. This, together with the general changes in climate, would also have reorganized the atmospheric chemistry over sites in Europe that is likely to be recorded in the groundwater's chemical and isotopic signatures

New constraints on the origin of the Australian Great Barrier Reef: Results from an international project of deep coring, 2001, Drilling Icfgbr,
Two new boreholes provide the first direct evidence of the age of the Australian Great Barrier Reef. An inner shelf sequence (total depth, 86 m; basal age = 210 {} 40 ka) comprises a dominantly siliciclastic unit (thickness [~]52-86 m), overlain by four carbonate units (total thickness 0-34 m). A shelf-edge and slope sequence (total depth 210 m) reveals three major sections: (1) a lower section of resedimented flows deposited on a lower slope, (2) a mid-section including intervals of corals, rhodoliths, and calcarenites with low- angle graded laminae, and (3) an upper section of four shelf- margin coral-reef units separated by karst surfaces bearing paleosols. Sr isotope and magnetostratigraphic data indicate that the central Great Barrier Reef is relatively young (post Bruhnes-Matuyama boundary time), and our best estimate for the onset of reef growth on the outer barrier system is ca. 600 {} 280 ka. This date suggests that reef initiation may have been related to the onset of full eccentricity-dominated glacio-eustatic sea-level oscillation as inferred from large-amplitude 'saw-tooth' 100 k.y. {delta}18O cycles (after marine isotope stage 17), rather than to some regional environmental parameter. A major question raised by our study is whether reef margins globally display a similar growth history. The possibility of a global reef initiation event has important implications for basin to shelf partitioning of CaCO3, atmospheric carbon dioxide levels, and global temperature change during Quaternary time

The sequence stratigraphy, sedimentology, and economic importance of evaporite-carbonate transitions: a review, 2001, Sarg J. F. ,
World-class hydrocarbon accumulations occur in many ancient evaporite-related basins. Seals and traps of such accumulations are, in many cases, controlled by the stratigraphic distribution of carbonate-evaporite facies transitions. Evaporites may occur in each of the systems tracts within depositional sequences. Thick evaporite successions are best developed during sea level lowstands due to evaporative drawdown. Type 1 lowstand evaporite systems are characterized by thick wedges that fill basin centers, and onlap basin margins. Very thick successions (i.e. saline giants) represent 2nd-order supersequence set (20-50 m.y.) lowstand systems that cap basin fills, and provide the ultimate top seals for the hydrocarbons contained within such basins.Where slope carbonate buildups occur, lowstand evaporites that onlap and overlap these buildups show a lateral facies mosaic directly related to the paleo-relief of the buildups. This facies mosaic, as exemplified in the Silurian of the Michigan basin, ranges from nodular mosaic anhydrite of supratidal sabkha origin deposited over the crests of the buildups, to downslope subaqueous facies of bedded massive/mosaic anhydrite and allochthonous dolomite-anhydrite breccias. Facies transitions near the updip onlap edges of evaporite wedges can provide lateral seals to hydrocarbons. Porous dolomites at the updip edges of lowstand evaporites will trap hydrocarbons where they onlap nonporous platform slope deposits. The Desert Creek Member of the Paradox Formation illustrates this transition. On the margins of the giant Aneth oil field in southeastern Utah, separate downdip oil pools have accumulated where dolomudstones and dolowackestones with microcrystalline porosity onlap the underlying highstand platform slope.Where lowstand carbonate units exist in arid basins, the updip facies change from carbonates to evaporite-rich facies can also provide traps for hydrocarbons. The change from porous dolomites composed of high-energy, shallow water grainstones and packstones to nonporous evaporitic lagoonal dolomite and sabkha anhydrite occurs in the Upper Permian San Andres/Grayburg sequences of the Permian basin. This facies change provides the trap for secondary oil pools on the basinward flanks of fields that are productive from highstand facies identical to the lowstand dolograinstones. Type 2 lowstand systems, like the Smackover Limestone of the Gulf of Mexico, show a similar relationship. Commonly, these evaporite systems are a facies mosaic of salina and sabkha evaporites admixed with wadi siliciclastics. They overlie and seal highstand carbonate platforms containing reservoir facies of shoalwater nonskeletal and skeletal grainstones. Further basinward these evaporites change facies into similar porous platform facies, and contain separate hydrocarbon traps.Transgressions in arid settings over underfilled platforms (e.g. Zechstein (Permian) of Europe; Ferry Lake Anhydrite (Cretaceous), Gulf of Mexico) can result in deposition of alternating cyclic carbonates and evaporites in broad, shallow subaqueous hypersaline environments. Evaporites include bedded and palmate gypsum layers. Mudstones and wackestones are deposited in mesosaline, shallow subtidal to low intertidal environments during periodic flooding of the platform interior.Highstand systems tracts are characterized by thick successions of m-scale, brining upward parasequences in platform interior settings. The Seven Rivers Formation (Guadalupian) of the Permian basin typifies this transition. An intertonguing of carbonate and sulfates is interpreted to occur in a broad, shallow subaqueous hypersaline shelf lagoon behind the main restricting shelf-edge carbonate complex. Underlying paleodepositional highs appear to control the position of the initial facies transition. Periodic flooding of the shelf interior results in widespread carbonate deposition comprised of mesosaline, skeletal-poor peloid dolowackestones/mudstones. Progressive restriction due to active carbonate deposition and/or an environment of net evaporation causes brining upward and deposition of lagoonal gypsum. Condensed sections of organic-rich black lime mudstones occur in basinal areas seaward of the transgressive and highstand carbonate platforms and have sourced significant quantities of hydrocarbons

Origin, evolution and residence time of saline thermal fluids (Balaruc springs, southern France): implications for fluid transfer across the continental shelf, 2002, Aquilina L, Ladouche B, Doerfliger N, Seidel Jl, Bakalowicz M, Dupuy C, Le Strat P,
Thermal fluids in the Balaruc-les-Bains peninsula, on the northeastern edge of the Than lagoon (southern France), supply the third largest spa in France. These thermal fluids interact with karst water in the Upper Jurassic aquifer composed of limestone and dolomite, forming two massifs to the east and north of the lagoon. These calcareous formations extend under the western end of the Than lagoon. Geochemical and isotope analyses were carried out in 1996 and 1998 on the thermal wells of the Balaruc-les-Bains peninsula to determine the origin of the thermal fluids and their interaction with subsurface karst water. The thermal fluids are a mixture of karst water and water of marine origin. H-3 and NO3 concentrations show that the proportion of present-day karst water in certain thermal wells is small (<5%), thus enabling us to define a 'pure' thermal end-member. The thermal end-member is itself a mixture of seawater and meteoric paleowater. Ca and Sr concentrations indicate a lengthy interaction with the carbonate substratum of the deep reservoir. Sr isotope signatures are very homogeneous and associated mainly with the dissolution of Jurassic carbonate, but also to evaporitic minerals. delta(13)C contents indicate that this dissolution is linked to deep inflow of CO2. Sr-87, trace element and rare earth element (REE) concentrations indicate that there is also a component, with a systematically minor participation, whose origin is deeper than the Jurassic carbonate and attributed to the Triassic and/or to the crystalline basement. Cl-36 concentrations are extremely low, indicating a residence time of around a hundred thousand years. The outflow temperature of the thermal fluids reaches 50 degreesC, and geothermometers indicate a reservoir temperature of around 80-100 degreesC, locating this aquifer at a depth of between 2000 and 2500 m. The geometry of the geological formations indicates a thrust plane associated with major basement faulting that separates the two calcareous massifs and seems to control the rise of deep thermal fluids from the Jurassic carbonate reservoirs and the participation of a deeper component from the basement and/or the Triassic. The present study shows that seawater can infiltrate at great depths and reside for long periods of time compared to the subsurface groundwater cycle. Compared to other highly saline fluids encountered in basement zones, these waters have a relatively well-preserved marine signature, probably due to the carbonate nature of the aquifer in which the fluids resided and their short residence time. (C) 2002 Elsevier Science B.V. All rights reserved

The hypogenic caves: a powerful tool for the study of seeps and their environmental effects, 2002, Forti P, Galdenzi S, Sarbu Sm,
Research performed in caves has shown the existence of significant effects of gas seeps, especially CO2 and H2S, within subterranean voids. Carbon dioxide causes important corrosive effects and creates characteristic morphologies (e.g., bell-shaped domes, bubble's trails), but is not involved in the deposition of specific cave minerals. On the other hand, in carbonate environments, hydrogen sulfide when oxidized in the shallow sections of the aquifer generates important corrosion effects and is also responsible for the deposition of specific minerals of which gypsum is the most common.Studies performed in the last few years have shown that H2S seeps in caves are associated with rich and diverse biological communities, consisting of large numbers of endemic species. Stable isotope studies (carbon and nitrogen) have demonstrated that these hypogean ecosystems are entirely based on in situ production of food by chemoautotrophic microorganisms using energy resulting from the oxidation of H2S.Although located only 20 m under the surface, Movile Cave does not receive meteoric waters due to a layer of impermeable clays and loess that covers the Miocene limestone in which the cave is developed. In the Frasassi caves, where certain amounts of meteoric water seep into the limestone, the subterranean ecosystems are still isolated from the surface. As the deep sulfidic waters mix with the oxigenated meteoric waters, sulfuric acid limestone corrosion is accelerated resulting in widespread deposition of gypsum onto the cave walls.Both these caves have raised a lot of interest for biological investigations regarding the chemoautotrophically based ecosystems, demonstrating the possibility of performing such studies in environments that are easily accessible and easy to monitor compared to the deep-sea environments where the first gas seeps were discovered

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