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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 static water level is the level of water in a well that is not being affected by withdrawal of ground water [6].?

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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 block (Keyword) returned 182 results for the whole karstbase:
Showing 16 to 30 of 182
POST JURASSIC BRITTLE TECTONICS OF THE HAMMAM ZRIBA MINE (NORTHEASTERN TUNISIA) AND RELATED KARST AND FLUORINE, BARYTINE AND CELESTITE OCCURRENCES IN CARBONATE ENVIRONMENTS, 1991, Melki F. , Zargouni F. ,
The Hammam Zriba mine is located in a lenticular horst structure, of varying width (0.3 to 1 km) and NNW-SSE strike over about 3 kms. The mineralization is strata-bound at the top of massive Portlandian limestones and is overlain by embedded Middle to Upper Campanian limestones with marl intercalations. This horst has formed during the late Jurassic as an emerged block bound by major faults that were remobilized later during various deformation stages. These facts are clearly documented by field observations and tectonic analysis essentially along the N160-N180 trending faults in the Portlandian lithofacies. These fractures have also controlled the palaeomorphological framework of the uppermost part of the Portlandian massive facies. The overlying Campanian unit exhibits onlap structures that rest on the irregular eroded karstified and mineralized surface which forms a screen surface for the upward channelized fluids and mineral formations in karst and graben. Fluids were apparently channelized by faults trending N070-N090 and N160-180, a few hundred metres long, that have facilitated karst, dissolution and mineral deposition during tectonic events

STRUCTURAL AND HYDROGEOLOGICAL ORIGIN OF TOWER KARST IN SOUTHERN CHINA (LIJIANG PLAIN IN THE GUILIN REGION), 1992, Drogue C, Bidaux P,
Spectacular towers (average 130 m high) are to be seen in the Lijiang plain near Guilin in middle and upper Devonian limestone forming a downthrown structural panel surrounded by the high relief of a cockpit karst. The limestone was fractured by at least three Triassic and Tertiary tectonic episodes. Statistical analysis of the altitudes of tower summits shows that they are distributed according to a log-normal law with a well marked mode at 250-280 m. This mode is very similar to that of the depression altitudes of the cockpit karst. It was deduced that tower summits and cockpit bottoms show that there was an ancient, relatively flat surface which was the basic level for flow in the surrounding karstic relief (water table at ground level). Fall in this ground water caused preferential karstic breakdown in very fractured zones, leaving the stronger blocks. This subsidence must have taken place in stages, as is shown by Pliocene and lower Quaternary fossil cavities at various altitudes of the towers. Observation of fracturing in the field, in aerial photographs and satellite images show that the edges of the towers are mainly transverse faults with sub-vertical planes

DISLOCATION OF THE EVAPORITIC FORMATIONS UNDER TECTONIC AND DISSOLUTION CONTROLS - THE MODEL OF THE DINANTIAN EVAPORITES FROM VARISCAN AREA (NORTHERN FRANCE AND BELGIUM), 1993, Rouchy J. M. , Groessens E. , Laumondais A. ,
Within the Franco-Belgian segment of the Hercynian orogen, two thick Dinantian anhydritic formations are known, respectively in the Saint-Ghislain (765 m) and Epinoy 1 (904 m) wells. Nevertheless, occurrences of widespread extended breccias and of numerous pseudomorphs of gypsum/anhydrite in stratigraphically equivalent carbonate deposits (boreholes and outcrops), suggest a larger extent of the evaporitic conditions (fig. 1, 2). The present distribution of evaporites is controlled by palaeogeographical differentiation and post-depositional parameters such as tectonics and dissolution. These latter have dissected the deposits formerly present in all the structural units. By using depositional, diagenetic and deformational characters of these formations, the article provides a model for the reconstruction of a dislocated evaporitic basin. This segment of the Hercynian chain is schematically composed of two main units (fig. 1, 3) : (1) the autochthonous or parautochthonous deposits of the Namur synclinorium, (2) the Dinant nappe thrusted northward over the synclinorium of Namur. The major thrust surface is underlined by a complex fault bundle (faille du Midi) seismically recognized over more than 100 km. A complex system of thrust slices occurs at the Hercynian front. Except for local Cretaceous deposits, most of the studied area has been submitted to a long period of denudation since the Permian. Sedimentary, faunistic and geochemical data argue for a marine origin of the brines which have generated the evaporites interbedded with marine limestones. Sedimentary structures. - The thick evaporitic formations are composed of calcium-sulfates without any clear evidence of the former presence of more soluble salts (with the exception of a possible carbonate-sulfate breccia in the upper part of the Saint-Ghislain formation). As in all the deeply buried evaporitic formations, the anhydrite is the main sulfate component which displays all the usual facies : pseudomorphs after gypsum (fig. 4A, B), nodular and mosaic (fig. 4C), laminated. The gypsum was probably an important component during the depositional phase despite the predominant nodular pattern of the anhydrite. Early diagenetic nodular anhydrite may have grown during temporary emersion of the carbonates (sabkha environments), but this mechanism cannot explain the formation of the whole anhydrite. So, most of the anhydrite structures result from burial-controlled gypsum --> anhydrite conversion and from mechanical deformations. Moreover, a complex set of diagenetic processes leads to various authigenic minerals (celestite, fluorite, albite, native sulfur, quartz and fibrous silica) and to multistaged carbonate <> sulfate replacements (calcite and dolomite after sulfate, replacive anhydrite as idiomorphic poeciloblasts, veinlets, domino-like or stairstep monocrystals...). These mineral transformations observed ill boreholes and in outcrops have diversely been controlled during the complex evolution of the series as : depositional and diagenetic pore-fluid composition, pressure and temperature changes with burial, bacterial and thermochemical sulfate reduction, deep circulations favored by mechanical brecciation, mechanical stresses, role of groundwater during exhumation of the series. Deformational structures. - A great variety of deformational structures as rotational elongation, stretching, lamination, isoclinal microfolding, augen-like and mylonitic structures are generated by compressive tectonic stresses (fig. 4D to J). The similarities between tectonic-generated structures and sedimentary (lamination) or diagenetic (pseudo-nodules) features could lead lo misinterpretations. The calcareous interbeds have undergone brittle deformation the style and the importance of which depend of their relative thickness. Stretching, boudins, microfolds and augen structures F, H. I) affect the thin layers while thicker beds may be broken as large fractured blocks dragged within flown anhydrite leading to a mylonitic-like structure (fig, 4G). In such an inhomogeneous formation made of interlayered ductile (anhydrite) and brittle (carbonate) beds, the style and the intensity of the deformation vary with respect to the relative thickness of each of these components. Such deformational features of anhydrite may have an ubiquitous significance and can result either from compressive constraints or geostatic movements (halokinesis). Nevertheless, some data evidence a relation with regional tangential stresses: (1) increase of the deformation toward the bottom of the Saint-Ghislain Formation which is marked by a deep karst suggesting the presence of a mechanical discontinuity used as a drain for dissolving solutions (fig. 3, 4); (2) structural setting (reversed series, internal slidings) of the Epinoy 1 formation under the Midi thrust. However, tectonic stresses also induce flowing deformations which have contributed to cause their present discontinuity. It can be assumed that the evaporites played an active role for the buckling of the regional structure as detachment or gliding layers and more specifically for the genesis of duplex structures. Breccia genesis. - Great breccia horizons are widely distributed in outcrops as well as in the subsurface throughout the greater part of the Dinant and Namur units (fig. 2). The wide distribution of pseudomorphosed sulfates in outcrops and the stratigraphical correlation between breccia and Saint-Ghislain evaporitic masses (fig. 2) suggest that some breccia (although not all) have been originated from collapse after evaporites solution. Although some breccia may result from synsedimentary dissolution, studied occurrences show that most of dissolution processes started after the Hercynian deformation and, in some cases, were active until recently : elements made of lithified and fractured limestones (Llandelies quarries) (fig. 5A), preservation of pseudomorphs of late replacive anhydrite (Yves-Gomezee) (fig. 5B, C), deep karst associated with breccia (Douvrain, Saint Ghislain, Ghlin boreholes) (fig. 3, 4, 5D)). Locally, the final brecciation may have been favored by a mechanical fragmentation which controlled water circulations (fig. 5E). As postulated by De Magnee et al. [19861, the dissolution started mostly after the Permian denudation and continued until now in relation with deep circulations and surface weathering (fig. 6). So, the above-mentioned occurrences of the breccia are logically explained by collapse after dissolution of calcium-sulfates interbeds of significant thickness (the presence of salt is not yet demonstrated), but other Visean breccia may have a different origin (fig. 5F). So, these data prove the extension of thick evaporitic beds in all the structural units including the Dinant nappe, before dissolution and deformation. Implications. - Distribution of Visean evaporites in northern France and Belgium is inherited from a complicated paleogeographic, tectonic and post-tectonic history which has strongly modified their former facies, thicknesses and limits (fig. IA, 6). Diversified environments of deposition controlled by both a palaeogeographical differentiation and water level fluctuations led to the deposition of subaqueous (gypsum) or interstitial (gypsum, anhydrite) crystallization. Nevertheless, most of the anhydrite structures can be interpreted as resulting from burial conversion of gypsum to anhydrite rather than a generalized early diagenesis in sabkha-like conditions. Deformation of anhydrite caused by Hercynian tangential stresses and subsequent flow mechanisms, have completed the destruction of depositional and diagenetic features. The tectonic deformations allow us to consider the role of the evaporites in the Hercynian deformations. The evaporites supplied detachment and gliding planes as suggested for the base of the Saint-Ghislain Formation and demonstrated by the structural setting of Epinoy 1 evaporites in reverse position and in a multi-system of thrust-slices below the Midi overthrust (fig. 7). So, although the area in which evaporation and precipitation took place cannot be exactly delineated in geographic extent, all the data evidence that the isolated thick anhydritic deposits represent relics of more widespread evaporites extending more or less throughout the different structural units of this Hercynian segment (fig. 1B). Their present discontinuity results from the combination of a depositional differentiation, mechanical deformations and/or dissolution

BEDDING KARST AND MULTILAYERED GROUNDWATER FLOWS IN KARSTIC BLOCK MOUNTAINS IN THE NORTHEAST OF MOUNT XISHAN, TAIYUAN, CHINA, 1993, Zhang D. C. ,
The hydrogeology of the northeastern part of Mt Xishan has historically been interpreted in terms of a simple unconfined aquifer model. The groundwater required is characterized by (1) karst terrain, (2) multilayered unconfined groundwater flow developed in block mountains involving rapid hanging discharges and (3) deep confined groundwater with a carbon 14 age of 1000-2800 years and low tritium content. The flows are partly towards the southern part of Mt Xishan, partly east towards the porous aquifers of the Nitun Basin and partly discharging through the Lancun Spring system. The spatial structure of karst aquifers in block mountains is elucidated by an understanding of stratigraphic, structural, lithological, climatic and karst geomorphological evolution. The actual complex hydrogeological conditions in the Mt Xishan area considered are demonstrated by a comprehensive model proposed by the author. Such a model may also be applied in other karstic block mountains

VARIOUS APPROACHES FOR FLOW SIMULATIONS IN A KARST - APPLICATION TO ROSPO MARE FIELD (ITALY), 1994, Corre B,
Rospo Mare field is located in the Adriatic Sea, 20 km of the Abruzzes coast, at an average depth of 80 m. The reservoir is a karst which is essentially conductive; yet unlike a conventional porous medium, it cannot be simulated by the usual tools and techniques of reservoir simulation. Therefore, several approaches were used to describe the flow mechanism during the production period in greater detail. The first approach consisted of generating three-dimensional images which were constrained by both petrophysical and geological factors and then, using up-scaling techniques, obtaining the equivalent permeabilities (scalar or tensorial) of grid blocks located in different zones within the karst. This approach shows that within the infiltration zone it is possible, whatever the scale, to find an equivalent homogeneous porous medium; on the other hand, within the epikarst this equivalent medium does not exist below pluridecametric dimensions. Thus it is impossible to study the sweeping mechanism on a small scale, so we must use a deterministic model which describes the network of pipes in the compact matrix, in which a waterflood is simulated by means of a conform finite-element model. This constituted the second approach. The third and final approach consisted of inventing a system of equations to analytically solve the pressure field in a network of vertical pipes which are intersected by a production drain and submitted to a strong bottom water-drive. This model allows us to simulate the water-oil contact rise within the reservoir and study the flows depending on the constraints applied to the production well. It appears that cross flows occur in the pipes even during the production period

RELATIONSHIP BETWEEN FRACTURES AND KARSTIFICATION - THE OIL-BEARING PALEOKARST OF ROSPO MARE (ITALY), 1994, Soudet H. J. , Sorriaux P. , Rolando J. P. ,
The Rospo Mare oil field is located in the Adriatic Sea, 20 km off the Italian coast. The reservoir lies at a depth of 1300 m and consists of a paleokarst oi Oligocene to Miocene age which developed within Cretaceous limestones, now covered by 1200 m of Mio-Pliocene sequences. The oil column is about 140 m 8 high. The karstic nature of the reservoir was identified through vertical, cored drill holes which allowed us to analyse the various solution features and the sedimentary infilling (speleothems, terra rossa, marine clays), as well as their vertical distribution. Erosion morphology at the top of the karst is highly irregular, including in particular paleovalleys as well as many pit-shaped sink holes. Detailed geophysical knowledge of that morphology helped to optimize the development of the field through horizontal drilling. Observations concerning the upper part of the reservoir were compared to a palaeokarst of the same age, outcropping widely onshore, in quarries located nearby. The Rospo Mare paleokarst is an integral part of the ante Miocene paleokarst assemblages of the periphery of the Mediterranean which were formed in tropical conditions. Only the fractures enhanced by meteoric water during the formation of the karat are important for reservoir connectivity. During the formation of the karst there were several phases of dissolution and infilling which modified the geometry of the open fissures and only these fractures play an important role in the reservoir drainage. Vertically we can distinguish three very different zones from top to bottom: at the top the epikarst (0-35 m) in a zone of extension. All the fractures have been enlarged by dissolution but the amount of infilling by clay is substantial. The clays are derived either from alteration of the karat fabric or by deposition during the Miocene transgression; the percolation zone (15-45 m) is characterized by its network of large fractures vertically enlarged by dissolution which corresponds to the relict absorption zones in the paleokarst. These fractures, which usually have a pluridecametric spacing, connect the epi-karst with the former sub-horizontal river system. This zone has been intersected by the horizontal wells during the field development. In this zone there are local, horizontal barriers oi impermeable clay which can block vertical transmissibility. In these low permeability zones the vertical fractures have not been enlarged due to dissolution hence the horizontal barrier; the zone of underground rivers (35-70 m) is characterized by numerous horizontal galleries which housed the subterranean ground water circulation. When these fissures are plurimetric in extent this can lead to gallery collapse with the associated fill by rock fall breccia. This can partly block the river system but always leaves a higher zone of free circulation with high permeabilities of several hundreds of Darcys. These galleries form along the natural fracture system relative to the paleohydraulic gradient which in some cases has been preserved. The zone below permanent ground water level with no circulation of fluids is characterized by dissolution limited to non-connected vugs. Very locally these fissures can be enlarged by tectonic fractures which are non-connected and unimportant for reservoir drainage. Laterally, only the uppermost zone can be resolved by seismic imaging linked with horizontal well data (the wells are located at the top of the percolation zone). The Rospo Mare reservoir shows three distinct horizontal zones: a relict paleokarst plateau with a high index of open connected fractures, (area around the A and B platforms); a zone bordering the plateau (to the north-east of the plateau zone) very karstified but intensely infilled by cap rock shales (Miocene - Oligocene age); a zone of intensely disturbed and irregular karst paleotopography which has been totally infilled by shales. The performance of the production wells is dependent on their position with respect to the three zones noted above and their distance from local irregularities in the karst paleotopography (dolines, paleovalleys)

Die Hhle von Shantipur bei Kathmandu (Nepal)., 1995, Gebauer, H. D.
[Nepal, Geol. Krtchen, Blockdiagramm]

Signification des remplissages des karsts de montagne, quelques cls lusage des splologues, 1995, Audra, P.
This paper is intended to cavers in order to help them identify the most significant mountain karst infillings. Carbonated varves sedimentation occurs during floodings in glacial environment. The varves block the deep parts of the networks. Pebbles sealings show a powerful erosion in the vadose zone, near glacial sinkholes. Gelifract spreadings are indicators of frost and snow action in periglacial environment. Reworked weathered rocks are the most ancient deposits, inherited from tertiary warm phases when karstification occurred under regolith covers. Their clearing is partly simultaneous with cave systems elaboration, in relation to the alpine uplift, during Pliocene. Speleothems are also warm or temperate climate indicators. Crystalline morphology reflects environmental characteristics, while their surface sight could have been smoothed during discharge reactivations. Finally, some infillings could have recorded neotectonic movements: broken speleothems, deformed clastic sediments, etc.

PROCESSES ASSOCIATED WITH MICROBIAL BIOFILMS IN THE TWILIGHT ZONE OF CAVES - EXAMPLES FROM THE CAYMAN ISLANDS, 1995, Jones B. ,
The twilight zone of a cave, an environment transitional between the well-illuminated environment outside the cave and the dark environment of the cave interior, is one of the most unusual microenvironments of the karst terrain. Walls in the twilight zone of caves on Grand Cayman and Cayman Brac are coated with a biofilm that incorporates a diverse assemblage of epilithic microbes and copious mucus. Most microbes are different from those found elsewhere in the karst terrains of the Cayman Islands, probably because they have adapted to life in the poorly illuminated twilight zone. None of the microbes employ an endolithic life mode, and less than 10% of them show evidence of calcification. The biofilm does, however, provide a medium in which a broad spectrum of destructive and constructive processes operate. Etching, the dominant destructive process, produces residual dolomite, residual calcite, blocky calcite, and spiky calcite. Constructive processes include precipitation of calcite, dolomite, gypsum, halite, and sylvite. Although filamentous microbes are common, examples of detrital grains trapped and bound to the substrate are rare. Destructive processes are more common than constructive ones

ELECTROMAGNETIC AND SEISMOACOUSTIC SIGNALS REVEALED IN KARST CAVES (CENTRAL ITALY), 1995, Bella F, Biagi Pf, Caputo M, Dellamonica G, Ermini A, Plastino W, Sgrigna V, Zilpimiani D,
Since 1988-89 equipment for detecting electric, magnetic and seismoacoustic signals has been running inside the Amare cave. The Amare cave is placed on the southern slope of the Gran Sasso chain, that is one of the largest karst areas of the Italian Apennines. In 1992, a similar equipment was installed inside the Cervo cave. This cave is located in another karst area of the Central Apennines, at about 50 km southwestwards of the Amare cave. In both these measurements sites, the signals are recorded every ten minutes in a digital form; the equipment is able to record signals, the frequency of which ranges from some hundred Hz to some hundred kHz. The data collected up to now seem to identify two different states that we call ''quiet'' and ''perturbed'' state. In the quiet state only electric and magnetic signals with the highest frequencies appear. These signals are connected with radio broadcastings and with the general lightnings activity of the Earth. A perturbed state is characterized by the sudden appearance of seismoacoustic signals coupled with electric and magnetic ones. This phenomenology is connected with local processes. Rainfall, atmospheric-pressure variations and some thermal effects are responsible for these local processes. A possible model is proposed to justify the observed phenomenology: micromovements of the limestone blocks that constitute the roof of the caves are invoked for the production of seismoacoustic signals. The electrification generated by these movements is invoked for the production of electric and magnetic signals

Biology of the Caves at Sinkhole Flat, Eddy County, New Mexico, 1996, Cokendolpher, J. C. , Polyak, V. J.
Quantification of limestone petrology and structure in a 25 km section of the northern Vaca Plateau, Belize, facilitated development of a model of speleogenesis and evolution of area caves and the karst landscape. The limestones in the study area are mostly depositional breccias developed between the mid-Cretaceous and mid-Tertiary adjacent to the emergent Maya Mountain Fault Block. Micritic and some fossiliferous-pelletic lithoclasts of the Cretaceous Campur Formation are cemented by sparite which formed in a shallow-sea high energy environment adjacent to the emergent area. Planes of structural weakness developed in the Campur Limestone have similar orientations to contemporary karst landform features including solution valleys, the long-axis of depressions, and cave passages. This correspondence suggests an important structural control on the formation and evolution of area caves and the karst landscape. Base level modification by way of valley incision and the development of secondary permeability enhanced interfluve development, causing caves to be truncated along valley sides and abandoned as active flow routes. The dry valleys and stair-step cave profiles indicate that the lowering of base level through time was interspersed with stable periods when horizontal cave passages were excavated.

Geomorphological aspects of gypsum karst areas with special emphasis on exposed karst., 1996, Sauro Ugo
Medium- to large-size forms in gypsum karst are described, including dolines, blind valleys, ploje-like depressions, collapses and positive and/or residual forms such as outliers, cone-like hills, dome-like hills, mesa-like tabular blocks and plateaux and breccia pipe hills. The similarities and/or difference between gypsum and carbonate forms are discussed.

Nickpoint recession in karst terrains: An example from the Buchan karst, southeastern Australia, 1996, Fabel D, Henricksen D, Finlayson Bl, Webb Ja,
Nickpoint recession in the Buchan karst, southeastern Australia, has resulted in the formation of an underground meander cut-off system in the Murrindal River valley. Three nickpoints have been stranded in the surface channel abandoned by the subterranean piracy, and these can be correlated with river terraces and epiphreatic cave passages in the nearby Buchan River valley. The presence of palaeomagnetically reversed sediments in the youngest cave passage in the Buchan valley implies that the topographically lowest nickpoint in the Murrindal valley is more than 730 ka old, and the other nickpoints are probably several million years old. The nickpoints are occasionally active during floods, but the diversion of most surface flow underground has slowed down their retreat to the extent that they have been effectively stationary for several million years Underground nickpoint migration has been by both incision within major phreatic conduits and their abandonment for lower-level passages. The nickpoints are all present in the upstream part of the cave system, but have not migrated past the sink in the river channel, despite the long period of time available for this to happen. The sink is characterized by collapsed limestone blocks; these filter out the coarse bedload from the river channel. As a result, erosion within the cave passages is dominantly solutional and therefore slower than in the surface channel, where it is mostly mechanical. In addition, to transmit a drop in base level the cave system requires the removal of a larger volume of rock than for the surface migration of a nickpoint, because any roof collapse material in the subsurface system must be removed. These factors have slowed the migration of the base-level changes through the subsurface system, and may be a general feature in caves that have diffuse sinks as their main inputs

Geomorphological evidence for anti-Apennine faults in the Umbro-Marchean Apennines and in the peri-Adriatic basin, Italy, 1996, Coltorti M, Farabollini P, Gentili B, Pambianchi G,
The Apennines are a relatively recent mountain chain which has been affected by uplift movements since the Upper Pliocene. In fact the remnants of an “erosional surface”, reduced close to base level, is preserved at the top of the relief. There is no general agreement on the geodynamic stress field and mechanisms which are creating the chain. However, it is largely accepted that uplift occurred together with the activation, on the western side of the chain, of extensive faults, oriented in the Apennine direction (NW-SE), which have been linked to the opening of the Tyrrhenian sea. A great debate is going on about the presence and significance of anti-Apennine faults (NE-SW) which have been observed by some authors but completely denied by others.The main evidence is represented by[ (1) block faulting of the remnants of the “erosional surface”. Along the Marchean Ridge, more elevated relief, delimiting relatively depressed areas, was created in correspondence with the Sibillini Mts. and Mt. S. Vicino. Similar evidence has been found in the Umbro-Marchean Ridge. Locally more than 1500 metres of displacement have been observed between more and less uplifted remnants. (2) Block faulting of fan deltas and related beaches, of Sicilian to Crotonian age, with more elevated sediments preserved between the Tronto and Tenna rivers and between the Musone and Esino rivers. Maximum displacement along a transect parallel to the coast is 200 metres. (3) fault-scarps affecting the Middle Pleistocene river terraces, as observed along the Esino, the Tronto, the Chienti and the Tenna river valleys. Maximum displacements are in the order of 50 metres. (4) Faulting of horizontal karst galleries and reorientation of the cave network, as in the Frasassi Gorge. Maximum displacements are about 100 metres. (5) Captures and alignments in the drainage network of the main river courses. (6) Large-scale gravitational movements, as in the Ancona landslide, and along the Chienti and Esino rivers.Their activation occurred in most cases after the Lower Pleistocene and although their displacements may be of relatively limited extent, dispite their recent activity, they played a major role in the modelling of the landscape. These faults display transtensive, extensional and trascurrent movements. Apart from the controversial geodynamic significance of these faults, from a geomorphological point of view they must be considered transverse elements of the stress field from blocks more or less uplifted along the Apennine chain.The importance and timing of activity of these faults in the Quaternary geomorphological evolution of the Umbria-Marchean Apennines is demonstrated using evidence usually underestimated by structural geologists, which can contribute to a debate based on a multidisciplinary approach

Yucatan karst features and the size of Chicxulub crater, 1996, Connors M, Hildebrand Ar, Pilkington M, Ortizaleman C, Chavez Re, Urrutiafucugauchi J, Granielcastro E, Camarazi A, Vasquez J, Halpenny Jf,
The buried Chicxulub impact structure is marked by a dramatic ring of sinkholes (called cenotes if containing water), and adjacent less prominent partial rings, which have been shown to coincide with maxima in horizontal gravity gradients and a topographic depression. These observations; along with the discreteness and spacing of the features, suggest a formation mechanism involving faulting in the outer slump zone of the crater, which would thus have a diameter of approximately 180 km, An opposing view, based primarily on the interpretation of gravity data, is that the crater is much larger than the cenote ring implies, Given the association of the known cenote ring with faults, we here examine northern Yucatan for similar rings in gravity, surface features and elevation, which we might expect to be associated with outer concentric faults in the case of a larger, possibly multiring, structure, No such outer rings have been found, although definite patterns are seen in the distribution of karst features outside the crater rim, We explain these patterns as resulting mainly from deformation related to the block fault zone that parallels the shelf edge of eastern Yucatan

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