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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. ...

Did you know?

That mechanical dispersion is the process whereby solutes are mechanically mixed during advective transport caused by the velocity variations at the microscopic level. synonymous with hydraulic dispersion [22].?

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Your search for shelf (Keyword) returned 68 results for the whole karstbase:
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Controversy over the great flood hypotheses in the Black Sea in light of geological, paleontological, and archaeological evidence, , Yankohombach Valentina, Gilbert Allan S. , Dolukhanov Pavel,
Legends describing a Great Flood are found in the narratives of several world religions, and the biblical account of Noah's Flood is the surviving heir to several versions of the ancient Mesopotamian Flood Myth. Recently, the story of the biblical deluge was connected to the Black Sea, together with the suggestion that the story's pre-Mesopotamian origins might be found in the Pontic basin [Ryan, W.B.F., Pitman, III, W.C., 1998. Noah's Flood: The New Scientific Discoveries About the Event That Changed History. Simon and Schuster, New York]. Based on the significance of this flood epic in the Judeo-Christian tradition, popular interest surged following publication of the idea.Currently, two Great Flood scenarios have been proposed for the Black Sea: (1) an Early Holocene event caused by catastrophic Mediterranean inflow at 7.2 ky BP (initial hypothesis of [Ryan et al., 1997. An abrupt drowning of the Black Sea shelf. Marine Geology 138, 119-126]) or 8.4 ky BP (modified hypothesis of [Ryan et al., 2003. Catastrophic flooding of the Black Sea. Annual Review of Earth and Planetary Science 31, 525-554.); and (2) a Late Pleistocene event brought on by Caspian influx between 16 and 13 ky BP [Chepalyga, A.L., 2003. Late glacial Great Flood in the Black Sea and Caspian Sea. GSA Annual Meeting and Exposition, 2-5 November 2003, Seattle, USA, p. 460]. Both hypotheses claim that the massive inundations of the Black Sea basin and ensuing large-scale environmental changes had a profound impact on prehistoric human societies of the surrounding areas, and both propose that the event formed the basis for the biblical Great Flood legend.This paper attempts to determine whether the preponderance of existing evidence sustains support for these Great Floods in the evolution of the Black Sea. Based upon established geological and paleontological data, it finds that the Late Pleistocene inundation was intense and substantial whereas the Early Holocene sea-level rise was not. Between 16 and 13 ky BP, the Late Neoeuxinian lake (the Late Pleistocene water body in the Pontic basin pre-dating the Black Sea) increased rapidly from ~-14 to -50 m (below the present level of the Black Sea), then rose gradually to ~-20 m by about 11 ky BP. At 11-10 ky BP (the Younger Dryas), it dropped to ~-50 m. When the Black Sea re-connected with the Sea of Marmara at about 9.5 ky BP, inflowing Mediterranean water increased the Black Sea level very gradually up to ~-20 m, and in so doing, it raised the salinity of the basin and brought in the first wave of Mediterranean immigrants. These data indicate no major drawdown of the Black Sea after the Younger Dryas, and they do not provide evidence for any catastrophic flooding of the Black Sea in the Early Holocene.In addition, available archaeological and paleoenvironmental evidence from the Pontic region reveal no recognizable changes in population dynamics between 14 and 6 ky BP that could be linked to an inundation of large magnitude [Dolukhanov, P., Shilik, K., 2006. Environment, sea-level changes, and human migrations in the northern Pontic area during late Pleistocene and Holocene times. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 297-318; Stanko, V.N., 2006. Fluctuations in the level of the Black Sea and Mesolithic settlement of the northern Pontic area. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 371-385]. More specifically, Mesolithic and early Neolithic archaeological data in southeastern Europe and Ukraine give no indications of shifts in human subsistence or other behavior at the time of the proposed catastrophic flood in the Early Holocene [Anthony, D., 2006. Pontic-Caspian Mesolithic and Early Neolithic societies at the time of the Black Sea Flood: A small audience and small effects. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 345-370; Dergachev and Dolukhanov, 2006. The Neolithization of the North Pontic area and the Balkans in the context of the Black Sea Floods. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 489-514]

Donnees geomorphologiques sur la region de Fresh Creek, Ile Andros (Bahama), 1974, Bourrouilh F,
A geomorphological study of the east coast of Andros (Fresh Creek area) shows the existence of a paleotopography represented by low-altitude hills (few metres). This paleotopography is protected by the presence of a calcitic Quaternary crust which covers Pleistocene calcarenite.In the western part of the area, there are long woody axes, oriented NE-SW, parallel to the channels of the creek. They end at two kilometres from the coast, along which is a second kind of lower hills, orthogonal to the first.The first axes can be interpreted as megaripples as seen at the present time on modern deposits (on the Great Bahama Bank) and fossilized by the upper crust. The second direction is made by accretion ripples along the coast.The surface of the Bahamian calcarenite has been studied. The Bahamian karst presents two topographical forms: “blue holes” like those outside the island, which are 60-80 m in diameter and both sparse and deep; and “washtub” dolines; these are numerous and shallow, and, from low altitude, exhibit a honeycombed aspect on the surface. This karstic topography with dolines and blue holes is also seen through the water of the Creek the hard bottom of which is covered only here and there with a few centimetres of sediments. Hence, there is a submerged karstic topography, made of the same elements as the aerial karst, but submerged by the Holocene transgression. The present karstic relief, in relation with the different eustatic levels of the Quaternary, has begun 120,000 years ago, according to the isotopic ages, and might be composed by different steps, difficult to show now, in the topography.The blue holes in the interior of the island of young and little evolved karst, were formed more by solution than by collapse of the karstic caves, because of the absence of a real river to drain the Andros shelf at the time of low sea levels. Blue holes of the inside of the island, as they are called, with submarine openings, have the same salinity as the water of the creek (17.5 g/l). The dolines with very low salinity (0.7 g/l to 3.8 g/l) are filled with stromatolites and charophytes, slowly forming sediments made up essentially of high-magnesian calcite.It seems that the Andros Island karst can be compared with that of the Yucatan, where there are round and deep open pits, called cenote, of which the Bahamian equivalent would be the blue holes which were drowned by the Holocene transgression.ResumeSur l'ile Andros, zone emergee du Grand Banc de Bahama, l'auteur montre l'existence d'une paleotopographie comprenant deux categories de rides d'orientation differente et semblant fossilisee par une croute calcitique recente et l'existence d'un karst aux formes jeunes, bien qu'heritage d'un karst holocene en voie de submersion. Ces formes sont des “blue holes” ou trous bleus circulaires (60 a 80 m de diametre) et peu nombreux, et des dolines, dites en baquet. Dans ces dolines se deposent actuellement des croutes stromatolithiques calcitiques dont l'etude est faite par diffractometrie de rayons X et microscopie electronique a balayage

Hydrogeological conditions in the Middle East, 1982, Burdon Dj,
The geology of Middle East is summarized under the subheadings: Precambrian basement, epicontinental sediments, geosynclinal and shelf deposits, Tertiary volcanics and Quaternary cover. The main tectonic episodes including epeirogenic movements, rifting and the Tertiary orogeny, are reviewed. The imposition of hydrometeorolocal and climatic conditions upon the regional geology provides the setting for the hydrogeological discussion. Five factors which influence infiltration to aquifers under conditions of low precipitation and high potential evaportranspiration are discussed. The predominance of fossil groundwater is the most striking hydrogeological phenomenon occurring on a regional scale in the Middle East. Its mode of formation during the pluvials is outlined and the isotopic evidence is reviewed. The main physical and chemical characteristics of fossil ground-waters are described. It is conservatively estimated that some 65 000 km3 of good- to medium-quality groundwater are stored in the great artesian basins of the Near East. These fossil ground-waters are a non-renewable natural resource. Current annual abstraction is, as yet, a small percentage of the total reserves but economic factors rather than the volume of reserves will determine the ultimate extent of their exploitation. The renewable groundwater resources of the Middle East tend, by comparison, to be of local rather than regional significance. Some originate outside the Middle East, coming in as surface flows in the Nile and Tigris-Euphrates and infiltrating into the sediments in and adjacent to the flood plains. Other renewable resources accumulate within the region where high precipitation and mountainous relief are associated. Such areas include the Djebel Akhdar of Cyrenacia, the Tertiary fold mountains from the Taurus through the Zagros to the Oman ranges, and the volcanic and basement highlands of Yemen, Asir and Ethiopa. Locally, in areas of lower precipitation, lenses of recent fresh groundwater float on regional more saline groundwater. In some areas subsurface flows towards and through wadi systems are also of importance

Depositional history of the late Pleistocene limestones of the Kenya coast, 1984, Braithwaite Cjr,
The coastal limestones of Kenya extend approximately 180 km N-S from Malindi to the Tanzanian border. They are at least 20 m thick and may be subdivided into sedimentary units representing major periods of marine deposition punctuated by sub-aerial erosion. Their foundations are formed by thick fluvial and aeolian quartz sands but there is local evidence of marine deposition following these. In the main limestone unit, deposited about 240,000 years ago, initial high energy shallow-shelf deposition was replaced by quiet water sediments with scattered corals. Sea level stood about 8 m higher than at present. Quartzose sands were confined to western areas. A return to shallow water heralded a new phase of emergence and erosion, producing karst surfaces and sub-aerial sediments. These are overlain by herring-bone cross-bedded quartz-rich calcarenites which were the products of a tidally dominated shelf and, at Watamu and Wasini, pass upwards into aeolian dune deposits. However, these were also emersed and subject to karst erosion before deposition of a further widespread marine limestone. Within this, coral knolls are well developed. Much of the sediment accumulated in shallow water, but the ecological succession indicates that knolls were at times in deeper waters. These deposits formed about 125,000 years ago when sea level ultimately stood 15-20 m above its present position. More recently in the area sea level has again fallen. However, the descent was not continuous and pauses were marked by marine terrace formation and subsequent karst erosion with sub-aerial deposition. Brief reversals caused both terraces and sediments to be overlain by thin marine deposits. Sea level paused at its present position about 30,000 years ago when the present reef platform was probably defined. It continued to fall to a maximum of about-120 m before rising to its existing level 7000 years ago and beginning the current cycle of sediment accumulation

Shallow-marine carbonate facies and facies models, 1985, Tucker M. E. ,
Shallow-marine carbonate sediments occur in three settings: platforms, shelves and ramps. The facies patterns and sequences in these settings are distinctive. However, one type of setting can develop into another through sedimentational or tectonic processes and, in the geologic record, intermediate cases are common. Five major depositional mechanisms affect carbonate sediments, giving predictable facies sequences: (1) tidal flat progradation, (2) shelf-marginal reef progradation, (3) vertical accretion of subtidal carbonates, (4) migration of carbonate sand bodies and (5) resedimentation processes, especially shoreface sands to deeper subtidal environments by storms and off-shelf transport by slumps, debris flows and turbidity currents. Carbonate platforms are regionally extensive environments of shallow subtidal and intertidal sedimentation. Storms are the most important source of energy, moving sediment on to shoreline tidal flats, reworking shoreface sands and transporting them into areas of deeper water. Progradation of tidal flats, producing shallowing upward sequences is the dominant depositional process on platforms. Two basic types of tidal flat are distinguished: an active type, typical of shorelines of low sediment production rates and high meteorologic tidal range, characterized by tidal channels which rework the flats producing grainstone lenses and beds and shell lags, and prominent storm layers; and a passive type in areas of lower meteorologic tidal range and higher sediment production rates, characterized by an absence of channel deposits, much fenestral and cryptalgal peloidal micrite, few storm layers and possibly extensive mixing-zone dolomite. Fluctuations in sea-level strongly affect platform sedimentation. Shelves are relatively narrow depositional environments, characterized by a distinct break of slope at the shelf margin. Reefs and carbonate sand bodies typify the turbulent shelf margin and give way to a shelf lagoon, bordered by tidal flats and/or a beach-barrier system along the shoreline. Marginal reef complexes show a fore-reef--reef core--back reef facies arrangement, where there were organisms capable of producing a solid framework. There have been seven such phases through the Phanerozoic. Reef mounds, equivalent to modern patch reefs, are very variable in faunal composition, size and shape. They occur at shelf margins, but also within shelf lagoons and on platforms and ramps. Four stages of development can be distinguished, from little-solid reef with much skeletal debris through to an evolved reef-lagoon-debris halo system. Shelf-marginal carbonate sand bodies consist of skeletal and oolite grainstones. Windward, leeward and tide-dominated shelf margins have different types of carbonate sand body, giving distinctive facies models. Ramps slope gently from intertidal to basinal depths, with no major change in gradient. Nearshore, inner ramp carbonate sands of beach-barrier-tidal delta complexes and subtidal shoals give way to muddy sands and sandy muds of the outer ramp. The major depositional processes are seaward progradation of the inner sand belt and storm transport of shoreface sand out to the deep ramp. Most shallow-marine carbonate facies are represented throughout the geologic record. However, variations do occur and these are most clearly seen in shelf-margin facies, through the evolutionary pattern of frame-building organisms causing the erratic development of barrier reef complexes. There have been significant variations in the mineralogy of carbonate skeletons, ooids and syn-sedimentary cements through time, reflecting fluctuations in seawater chemistry, but the effect of these is largely in terms of diagenesis rather than facies

Palokarst palozoque en Antarctique, 1986, Maire R. , Laurent R.
PALEOZOIC KARST IN ANTARCTICA - Karst features in Antarctica have been rarely observed. In their study on the geology of the Beardmore Glacier area in the Transantarctic Mountains (south of Ross Ice Shelf), BARRET and al. (1968) describe a pre-glacial karst topography (Mt. Counts) and especially a former cave (diameter 10 m) 10 m below the erosion surface and filled with coarse green sandstone. Shaped in the "Shackleton limestone" (Low to Middle Cambrian) probably during the Permo-Carboniferous (hercynian cycle), this karst is fossilised by the Pagoda formation, a permian tillite of the Beacon sequence (Devonian-Permian- Triassic).

Regional dolomitization of subtidal shelf carbonates: Burlington and Keokuk Formations (Mississippian), Iowa and Illinois, 1987, Harris David C. , Meyers William J. ,
Cathodoluminescent petrography of crinoidal limestones and dolomites from the Mississippian (Osagean) Burlington and Keokuk Formations in Iowa and Illinois has revealed a complex diagenetic history of calcite cementation, dolomitization, chertification and compaction. Dolomite occurs abundantly in subtidal, open-marine facies throughout the study area. Three luminescently and chemically distinct generations of dolomite can be recognized regionally. Dolomite I, the oldest generation, is luminescent, thinly zoned, and occurs mainly as a replacement of lime mud. Dolomite II has dull red unzoned luminescence, and occurs mainly as a replacement of dolomite I rhombs. Dolomite III is non-luminescent, and occurs as a syntaxial cement on, and replacement of, older dolomite I and II rhombs. Petrography of these dolomite generations, integrating calcite cement stratigraphy, chertification and compaction histories has established the diagenetic sequence. Dolomites I and II pre-date all calcite cements, most chert, intergranular compaction and styloites. Dolomite III precipitation occurred within the calcite cement sequence, after all chert, and after at least some stylolitization. The stratigraphic limit of these dolomites to rocks older than the St Louis Limestone (Meramecian) suggests that dolomitization took place before or during a regional mid-Meramecian subaerial unconformity. A single dolomitization model cannot reasonably explain all three generations of dolomite in the Burlington and Keokuk limestones. Petrographic and geochemical characteristics coupled with timing constraints suggest that dolomite I formed in a sea water-fresh water mixing zone associated with a meteoric groundwater system established beneath the pre-St Louis unconformity. Dolomite II and III may have formed from externally sourced warm brines that replaced precursor dolomite at shallow burial depths. These models therefore suggest that the required Mg for dolomite I was derived mainly from sea water, whereas that for dolomites II and III was derived mainly from precursor Burlington--Keokuk dolomites through replacement or pressure solution

Geology of the Capitan shelf margin ? subsurface data from the northern Delaware Basin, 1989, Garber R. A. , Grover G. A. , Harris M.

Yates and other Guadalupian (Kazanian) oil fields, U. S. Permian Basin, 1990, Craig Dh,
More than 150 oil and gas fields in west Texas and southeast New Mexico produce from dolomites of Late Permian (Guadalupian [Kazanian]) age. A majority of these fields are situated on platforms or shelves and produce from gentle anticlines or stratigraphic traps sealed beneath a thick sequence of Late Permian evaporites. Many of the productive anticlinal structures are elongate parallel to the strike of depositional facies, are asymmetrical normal to facies strike, and have flank dips of no more than 6{degrees}. They appear to be related primarily to differential compaction over and around bars of skeletal grainstone and packstone. Where the trapping is stratigraphic, it is due to the presence of tight mudstones and wackestones and to secondary cementation by anhydrite and gypsum. The larger of the fields produce from San Andres-Grayburg shelf and shelf margin dolomites. Cumulative production from these fields amounts to more than 12 billion bbl (1.9 x 109 m3) of oil, which is approximately two-thirds of the oil produced from Palaeozoic rocks in the Permian Basin. Eighteen of the fields have produced in the range from 100 million to 1.7 billion bbl (16-271 x 106 m3). Among these large fields is Yates which, since its discovery in October 1926, has produced almost 1.2 billion bbl (192 x 106 m3) out of an estimated original oil-in-place of 4 billion bbl (638 x 106 m3). Flow potentials of 5000 to 20 000 bbl (800 to 3200 m3) per day were not unusual for early Yates wells. The exceptional storage and flow characteristics of the Yates reservoir can be explained in terms of the combined effects of several geologic factors: (1) a vast system of well interconnected pores, including a network of fractures and small caves; (2) oil storage lithologies dominated by porous and permeable bioclastic dolograinstones and dolopackstones; (3) a thick, upper seal of anhydrite and compact dolomite; (4) virtual freedom from the anhydrite cements that occlude much porosity in other fields which are stratigraphic analogues of Yates; (5) unusual structural prominence, which favourably affected diagenetic development of the reservoir and made the field a focus for large volumes of migrating primary and secondary oil; (6) early reservoir pressures considerably above the minimum required to cause wells to flow to the surface, probably related to pressures in a tributary regional aquifer

Quaternary engineering geology, 1991, Fookes Pg,
The geological and geomorphological effects on the Earth's surface during the Quaternary have been both extensive and profound. An attempt has been made to simplify and summarize these effects by considering the principal agencies at work during the Quaternary: plate tectonics, rapidly rising sea levels, rapidly falling sea levels, rapidly cooling climates and rapidly warming climates. The resulting series of major glacial and interglacial episodes have had far-reaching consequences for the engineering characteristics of the Earth's surface. In attempting to summarize these major omissions will have been inevitable and errors will have occurred due to compression of the subject and its interpretation in a simplified manner. Table 2 summarizes the approach of the paper in itemising the principal Quaternary events, causes and effects, consequences to landscape and inferences to engineering. Each of the six events has been developed into larger tables and accompanied by some discussion and examples. The principal consequences of the events for engineering have been the production of glacial and periglacial soils,over large areas of the northern and southern hemispheres; changes in the sediment patterns on the coasts, the continental shelves and in river systems; and the development of weathering profiles of very variable type and distribution leading to development of in situ residual soils of many different engineering characteristics. The major shifts in climate associated with these events have led to migration of various surface forms which are now being exposed or covered by the present regime, leading to many active slope processes with potential instability for engineering projects and unexpected distribution of materials. The continuing events of plate tectonics which precedes the Quaternary by a long period of geological time explain the distribution of earthquake systems, growing coastlines and mountains, and the pattern of volcanic areas with their own suites of rock and soil of significance for the engineer. ... This 250-word extract was created in the absence of an abstract

CYCLOSTRATIGRAPHY OF MIDDLE DEVONIAN CARBONATES OF THE EASTERN GREAT-BASIN, 1995, Elrick M,
Middle Devonian carbonates (250-430 m thick) of the eastern Great Basin were deposited along a low energy, westward-thickening, distally steepened ramp. Four third-order sequences can be correlated across the ramp-to-basin transition and are composed of meter-scale, upward-shallowing carbonate cycles (or parasequences). Peritidal cycles (shallow subtidal facies capped by tidal-flat laminites) constitute 90% of all measured cycles and are present across the entire ramp. The peritidal cycles are regressive- and transgressive-prone (upward-deepening followed by upward-shallowing facies trends). Approximately 80% of the peritidal cycle caps show evidence of prolonged subaerial exposure including sediment-filled dissolution cavities, horizontal to vertical desiccation cracks, rubble and karst breccias, and pedogenic alteration; locally these features are present down to 2 m below the cycle caps. Subtidal cycles (capped by shallow subtidal facies) are present along the middle-outer ramp and ramp margin and indicate incomplete shallowing. submerged subtidal cycles (64% of all subtidal cycles) are composed of deeper subtidal facies overlain by shallow subtidal facies. Exposed subtidal cycles are composed of deeper subtidal facies overlain by shallow subtidal facies that are capped by features indicative of prolonged subaerial exposure (dissolution cavities and brecciation). Average peritidal and subtidal cycle durations are between approximately 50 and 130 k.y. (fourth- to fifth-order). The combined evidence of abundant exposure-capped peritidal and subtidal cycles, transgressive-prone cycles, and subtidal cycles correlative with updip peritidal cycles indicates that the cycles formed in response to fourth- to fifth-order, glacio-eustatic sea-level oscillations. Sea-level oscillations of relatively low magnitude (< 10 m) are suggested by the abundance of peritidal cycles, the lack of widely varying, water-depth-dependent facies within individual cycles, and the presence of noncyclic stratigraphic intervals within intrashelf-basin, slope, and basin facies. Noncyclic intervals represent missed subtidal beats when the seafloor lay too deep to record the effects of the short-term sea-level oscillations. Exposure surfaces at the tops of peritidal and subtidal cycles represent one, or more likely several, missed sea-level oscillations when the platform lay above fluctuating sea level, but the amplitude of fourth- to fifth-order sea-level oscillation(s) were not high enough to flood the ramp. The large number of missed beats (exposure-capped cycles), specifically in Sequences 2 and 4, results in Fischer plots that show poorly developed rising and falling limbs (subdued wave-like patterns); consequently the Fischer plots: are of limited use as a correlation tool for these particular depositional sequences. The abundance of missed beats also explains why Milankovitch-type cycle ratios (similar to 5:1 or similar to 4:1) are not observed and why such ratios would not be expected along many peritidal-cycle-dominated carbonate platforms

Karst Geomorphology and Hydrology of Gunung Tempurung, Perak, Malaysia, 1995, Gilleson David , Holland Ernst , Davies Gareth

Gunung Tempurung is a 600-metre high limestone tower in the Kinta Valley located to the south of the city of Ipoh, Malaysia. The tower contains at least one extensive cave system, Gua Tempurung, which has a length of approximately 4800 metres and a vertical range of about 200 metres. The tower is an erosional remnant of a thick sequence of Silurian - Permian Limestones initially formed as a shelf deposit near an ancient coastline. The carbonate rocks lie adjacent to, and are laterally bounded by, Late Mesozoic granite plutoniic rocks emplaced by activity related to the Late Triassic uplift from plate boundary stresses along the western edge of the Malay Peninsular. The limestones have been folded and compressed between the granites and have been altered by contact metamorphism to marbles and skarn. Hydrothermal mineralisation of the limestone host rock has yeilded deposits of tin, with some tungsten minerals and other minor ores. In the central part of the karst tower a river-cave system, Gua Tempurung, developed from local damming of the north and south outlets of a small catchment derived from the granite upland area to the east. In several locations inside the dry upper chambers of the cave, vein deposits of tin (cassiterite) are evident in walls and ceilings. Additionally alluvial tin deposits derived from the Old Alluvium are present in the cave.


Prhistoire et karst littoral : la grotte Cosquer et les calanques mar_seillaises (Bouches-du-Rhne, France), 1996, Collinagirard, J.
The Cosquer Cave is a French palaeolithic painted and engraved cave (27000/ 18500 BP) which is located under the sea, in the urgonian limestones of Cap Morgiou ("Massif des Calanques"; Marseille). The en trance was submerged at the end of the last glacial stage and is presently 37 m under sea level. A synthesis about the Cosquer cave environmental studies is presented here. Structural studies show that cave planimetry is determined by Cap Morgiou fracturations (mainly NW/SE and N/S vertical faults). Through archaeological studies, a concretion breaking period can be dated between 27000 and 18000 BP. Geomorphological study of the continental shelf at the foot of the Cosquer cave area shows fossils shorelines at -36 m, -50/55 m, -90 m, -100 m depth. Radiocarbon datings from shells collected in 100m sediments yielded a date of 13 250 BP. Direct scuba diving observations and submarine clive profiles sketching show several eustatic stand-still levels between -36 m and the sea surface indicating a probable tectonic stability during the last 10000 years.

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

Petroleum geology of the Black Sea, 1996, Robinson A. G. , Rudat J. H. , Banks C. J. , Wiles R. L. F. ,
The Black Sea comprises two extensional basins formed in a back-arc setting above the northward subducting Tethys Ocean, close to the southern margin of Eurasia. The two basins coalesced late in their post-rift phases in the Pliocene, forming the present single depocentre. The Western Black Sea was initiated in the Aptian, when a part of the Moesian Platform (now the Western Pontides of Turkey) began to rift and move away to the south-east. The Eastern Black Sea probably formed by separation of the Mid-Black Sea High from the Shatsky Ridge during the Palaeocene to Eocene. Subsequent to rifting, the basins were the sites of mainly deep water deposition; only during the Late Miocene was there a major sea-level fall, leading to the development of a relatively shallow lake. Most of the margins of the Black Sea have been extensively modified by Late Eocene to recent compression associated with closure of the Tethys Ocean. Gas chromatography--mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the Black Sea can be explained by generation from an oil-prone source rock of most probably Late Eocene age (although a wider age range is possible in the basin centres). Burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post-rift basin. A Palaeozoic source rock may have generated gas condensate in the Gulf of Odessa. In Bulgarian waters, the main plays are associated with the development of an Eocene foreland basin (Kamchia Trough) and in extensional structures related to Western Black Sea rifting. The latter continue into the Romanian shelf where there is also potential in rollover anticlines due to gravity sliding of Neogene sediments. In the Gulf of Odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures. Small gas and oil discoveries around the Sea of Azov point to further potential offshore around the Central Azov High. In offshore Russia and Georgia there are large culminations on the Shatsky Ridge, but these are mainly in deep water and may have poor reservoirs. There are small compressional structures off the northern Turkish coast related to the Pontide deformation; these may include Eocene turbidite reservoirs. The extensional fault blocks of the Andrusov Ridge (Mid-Black Sea High) are seen as having the best potential for large hydrocarbon volumes, but in 2200 m of water

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