The Experts below are selected from a list of 9606 Experts worldwide ranked by ideXlab platform
Joan R. Mylroie - One of the best experts on this subject based on the ideXlab platform.
-
Void Development on carbonate coasts: creation of anchialine habitats
Hydrobiologia, 2011Co-Authors: John E. Mylroie, Joan R. MylroieAbstract:Anchialine Caves in coastal locations develop in two ways: by pseudokarst processes that form talus Caves, sea Caves, tafoni, fissure Caves and lava tubes, and by karst dissolutional processes that form stream Caves, flank margin Caves, and blue holes. Pseudokarst Caves are of minor importance in anchialine Cave habitat Development, with some lava tubes being notable exceptions. Dissolution Caves provide the most extensive, variable, and long-term environments for anchialine habitats. The Carbonate Island Karst Model (CIKM) allows dissolutional Cave Development in carbonate coasts to be understood as the interplay between freshwater and marine water mixing, sea-level change, rock maturity, and interaction with adjacent non-carbonate rocks. Glacioeustatic sea-level changes of the Quaternary have moved all coastal anchialine Cave environments repeatedly through a vertical range of over 100 m, and modern anchialine environments could not develop at their current elevations until ~4,000 years ago when sea level reached its present position. Blue holes form by a variety of mechanisms, but the most common is upward stoping and collapse from deep dissolutional voids. As a result, they provide vertical connection between different levels of horizontal Cave Development produced by a variety of earlier sea-level positions. Blue holes are overprinted by successive sea-level fluctuations; each sea-level event adds complexity to the habitats within blue holes and the Cave systems they connect. Blue holes can reach depths below the deepest glacioeustatic sea-level lowstand, and thereby provide a refugia for anchialine species when Cave passages above are drained by Quaternary sea-level fall. Blue holes represent the most significant anchialine Cave environment in the world, and may provide clues to anchialine Cave species colonization and speciation events.
-
Fresh-water lens anisotropy and flank margin Cave Development, Fais Island, FSM
2011Co-Authors: John E. Mylroie, Joan R. Mylroie, John W. Jenson, Rob MaccrackenAbstract:Fais Island, which lies about 200 km east of Yap, Federated States of Micronesia, in the Caroline Islands of the Western Pacific Ocean, is a small uplifted carbonate platform. Modern fresh water lens discharge is concentrated where high-relief cliffs extend seaward beyond the beach and reef flats. Fresh water flow from the beaches and reef flats is small to insignificant. Flank margin Caves are also concentrated in these headlands and are conspicuously absent in the vertical cliffs inland of beach and reef flat areas. The original porosity in the pre-Holocene carbonate rocks of Fais has been rearranged into high-permeability flow systems by repeated exposure to the fresh water lens. The older headlands that extend past the lower permeability beaches and reef flats, conduct water from the lens to the sea. At the same time, flank margin Cave Development between headlands was diminished by the lack of fresh water lens discharge in those areas. A large closed-contour depression containing a fresh water pool looks at first sight like a sinkhole, but is in fact, an ancient well dug into terraced Holocene sands that infill a reentrant in a paleo-sea cliff. The low relative permeability of these sands creates a more substantial fresh water lens than is available
-
Flank Margin Cave Development in Carbonate Talus Breccia Facies: An Example from Cres Island, Croatia
Acta Carsologica, 2010Co-Authors: Bojan Otoničar, John E. Mylroie, Nenad Buzjak, Joan R. MylroieAbstract:Plava Grota, Cres Island, Croatia, is a flank margin Cave developed in a coastal setting in talus breccia facies. The internal Cave geometry of small entrances, intersecting adjacent chambers, remnant dissolutional bedrock pillars, and low arches matches diagnostic features used to separate flank margin Caves from epigenic stream Caves on one hand, and sea Caves on the other. Plava Grota is found, along with adjacent smaller Caves, solely in a breccia facies that is most probably of Pleistocene age. This breccia is comprised of clasts derived from diagenetically mature, or telogenetic, Cretaceous carbonate rocks. The clasts are loosely cemented by vadose calcite cements. The breccia facies provide a three-dimensional porosity and permeability structure that behaves hydraulically in a manner similar to the high primary porosity and permeability of young eogenetic carbonate rocks in settings such as the Bahamas or Puerto Rico, and the many flow paths found in highly-tectonized telogenetic carbonate rocks in New Zealand. Plava Grota is the first described flank margin Cave from the coastal carbonate rocks of the Adriatic Sea. According to present sea-level position in relation to the Cave, fresh-water springs in and adjacent to the Cave, general tectonic subsidence of the area and Quaternary eustatic sea-level fluctuations, we propose the hypotheses that the Cave was primarily formed during the MIS 5e sea-level highstand.
-
FLANK MARGIN Cave Development IN CARBONATE TALUS BRECCIA FACIES: AN EXAMPLE FROM CRES ISLAND, CROATIA JAMA TIPA »FLANK MARGIN«, NASTALA V POBOČNI BREČI V OBMOČJU MEŠANJA SLADKE IN SLANE VODE: PRIMER Z OTOKA CRESA NA HRVAŠKEM
2010Co-Authors: Nenad Buzjak, John E. Mylroie, Joan R. MylroieAbstract:Abstract UDC 911.2:551.44(497.5) Bojan Otonicar, Nenad Buzjak, John Mylroie & Joan Mylroie: Flank margin Cave Development in carbonate talus breccia fa-cies: An example from Cres Island, Croatia Plava Grota, Cres Island, Croatia, is a flank margin Cave devel-oped in a coastal setting in talus breccia facies. The internal Cave geometry of small entrances, intersecting adjacent chambers, remnant dissolutional bedrock pillars, and low arches matches diagnostic features used to separate flank margin Caves from epigenic stream Caves on one hand, and sea Caves on the other. Plava Grota is found, along with adjacent smaller Caves, solely in a breccia facies that is most probably of Pleistocene age. This breccia is comprised of clasts derived from diagenetically ma-ture, or telogenetic, Cretaceous carbonate rocks. The clasts are loosely cemented by vadose calcite cements. The breccia facies provide a three-dimensional porosity and permeability struc-ture that behaves hydraulically in a manner similar to the high primary porosity and permeability of young eogenetic carbon-ate rocks in settings such as the Bahamas or Puerto Rico, and the many flow paths found in highly-tectonized telogenetic carbonate rocks in New Zealand. Plava Grota is the first de-scribed flank margin Cave from the coastal carbonate rocks of the Adriatic Sea. According to present sea-level position in rela-tion to the Cave, fresh-water springs in and adjacent to the Cave, general tectonic subsidence of the area and Quaternary eustatic sea-level fluctuations, we propose the hypotheses that the Cave was primarily formed during the MIS 5e sea-level highstand.
-
Flank Margin Cave Development in Telogenetic Limestones of New Zealand
Acta Carsologica, 2008Co-Authors: John E. Mylroie, Joan R. Mylroie, Campbell S. NelsonAbstract:Coastal limestone outcrops, typically with advanced levels of diagenetic maturity (i.e., are telogenetic carbonates), were examined on NorthIsland (Raglan Harbour, Kawhia Harbour, Napier, and Waipu Cove) and SouthIsland (Pohara, Paturau River, Punakaiki, Kakanui, and Kaikoura), New Zealand, to determine if flank margin Caves, produced by mixing dissolution, were present. In coastal settings, Caves in carbonate rock can be the outcome of pseudokarst process, primarily wave erosion, as well as karst processes not associated with freshand sea-water mixing suchas epikarst features and conduit-flow stream Caves. Flank margin Caves were successfully differentiated from other Cave types by the following criteria: phreatic dissolutional morphologies at the wall rock and chamber scales; absence of high-velocity, turbulent-flow wall sculpture and sediment deposits; and lack of integration of adjacent Caves into a continuous flow path. The active tectonics of New Zealand creates a variable sea-level situation. The relatively short time of sea-level stability limits the size of the New Zealand flank margin Caves compared to tectonically-stable environments, suchas the Bahamas, where glacioeustasy alone controls sea-level stability. Uplift events can be identified as slow and steady when the flank margin Caves are uniformly elongated in the vertical direction, and episodic when the flank margin Caves show widening and tube development at discrete horizons that cut across rock structure. New Zealand flank margin Caves contain information on uplift duration and rates independent of other commonly used measures, and therefore can provide a calibration to other methods.
John E. Mylroie - One of the best experts on this subject based on the ideXlab platform.
-
Caves and Karst of New England and Eastern New York
Glaciation and Speleogenesis, 2015Co-Authors: Max P. Cooper, John E. MylroieAbstract:Dissolutional Cave Development in the New England and eastern New York area is primarily in Cambro-Ordovician marbles that extend in a north-south band along the western boundary of Connecticut, Massachusetts, and Vermont, and similarly in the eastern-most portion of New York. Some Precambrian marbles, and some Ordovician carbonates are also found in this area. Maine has karst areas, but they are remote, low-lying, and poorly understood. Cave Development appears to have been mostly post-glacial, with a few relict (pre-glacial) large Caves (e.g. Aeolus Bat Cave, Morris Cave), and several large Caves that are likely combination Caves that while active in the current deranged hydrology, have passages inherited from pre-glacial times (e.g. Vermonster, Carthusian and Merlins Caves). Joint activation by isostatic rebound following ice withdrawal, coupled with large glacial lake discharges, are argued to be the prime initiator of Cave Development. The Caves that result are commonly shallow, and vulnerable to removal by the next glaciation, indicating a cyclic nature to Cave Development and destruction, avoided only by the larger, deeper or fortuitously placed Cave systems. A general lack of glacial sediments in smaller Caves is a good indicator that many Caves are post-glacial, though some examples exist of pre-glacial Caves containing sediment (e.g. Weybridge Cave). Cave science has been sparse and sporadic in this region, but a recent wave of papers, coupled with new discoveries of major Caves, indicates that this region will be a greater participant in speleology in the future.
-
Caves and Karst of the Deformed Siluro-Devonian Carbonates, South Central New York
Glaciation and Speleogenesis, 2015Co-Authors: Max P. Cooper, John E. MylroieAbstract:The Siluro-Devonian Helderberg Group carbonates and the mid-Devonian Onondaga Limestone of the Hudson River Valley were highly deformed by the Acadian Orogeny, which limited subsequent outcrop extent and catchment. Glaciation overprinted the tectonic structure and obliterated, modified, and engendered Cave Development. Ice movement was north to south, parallel to the structural grain and the adjacent Hudson River, and differentiating the controls of Cave Development is difficult. Clarksville Cave and Onesquethaw Cave appear pre- and post-glacial, respectively, despite similar sizes in excess of 1 km (0.63 miles), and both show significant structural control. Farther south, the Joralemon Park Caves display maze Development initiated post-glacially, adjacent to pre-glacial Cave remnants in a deranged drainage setting. Pompeys Cave is developed in a limestone member of the Rondout Formation, a member not present west and north in the main Helderberg Plateau. The Cave is a single stream-capture passage of large size with a backflood maze overprint upstream of a major collapse area; despite the large size, the Cave otherwise fits the criteria of being post-glacial in origin. Mystery (Surprise) Cave at 3 km (2 miles) is the longest Cave in this region, and sits near the southern glacial boundary and appears pre-glacial in origin. Numerous other small Caves are strewn along the Hudson River Valley, and all show an interesting interplay between structure, lithology and glaciation.
-
Unusual polygenetic void and Cave Development in dolomitized Miocene chalks on Barbados, West Indies
International Journal of Speleology, 2013Co-Authors: Jonathan B. Sumrall, John E. Mylroie, Hans G. MachelAbstract:Barbados provides an unusual case of polygenetic Cave Development within dolomitized chalks and marls of the Miocene Oceanics Group. These diagenetic processes are driven by a succession and interplay of tectonic uplift, fracturing, hypogene fluid injection, overprinting by mixing zone diagenesis, and mechanical and biological erosion in the current littoral zone. The significance of the voids and Caves within the chalks on Barbados are: 1) these appear to be the first dissolution Caves documented in dolomitized chalk, and 2) these features show a polygenetic origin documenting the diagenetic changes in lithology that allowed the Development and preservation of these Cave types
-
Void Development on carbonate coasts: creation of anchialine habitats
Hydrobiologia, 2011Co-Authors: John E. Mylroie, Joan R. MylroieAbstract:Anchialine Caves in coastal locations develop in two ways: by pseudokarst processes that form talus Caves, sea Caves, tafoni, fissure Caves and lava tubes, and by karst dissolutional processes that form stream Caves, flank margin Caves, and blue holes. Pseudokarst Caves are of minor importance in anchialine Cave habitat Development, with some lava tubes being notable exceptions. Dissolution Caves provide the most extensive, variable, and long-term environments for anchialine habitats. The Carbonate Island Karst Model (CIKM) allows dissolutional Cave Development in carbonate coasts to be understood as the interplay between freshwater and marine water mixing, sea-level change, rock maturity, and interaction with adjacent non-carbonate rocks. Glacioeustatic sea-level changes of the Quaternary have moved all coastal anchialine Cave environments repeatedly through a vertical range of over 100 m, and modern anchialine environments could not develop at their current elevations until ~4,000 years ago when sea level reached its present position. Blue holes form by a variety of mechanisms, but the most common is upward stoping and collapse from deep dissolutional voids. As a result, they provide vertical connection between different levels of horizontal Cave Development produced by a variety of earlier sea-level positions. Blue holes are overprinted by successive sea-level fluctuations; each sea-level event adds complexity to the habitats within blue holes and the Cave systems they connect. Blue holes can reach depths below the deepest glacioeustatic sea-level lowstand, and thereby provide a refugia for anchialine species when Cave passages above are drained by Quaternary sea-level fall. Blue holes represent the most significant anchialine Cave environment in the world, and may provide clues to anchialine Cave species colonization and speciation events.
-
Fresh-water lens anisotropy and flank margin Cave Development, Fais Island, FSM
2011Co-Authors: John E. Mylroie, Joan R. Mylroie, John W. Jenson, Rob MaccrackenAbstract:Fais Island, which lies about 200 km east of Yap, Federated States of Micronesia, in the Caroline Islands of the Western Pacific Ocean, is a small uplifted carbonate platform. Modern fresh water lens discharge is concentrated where high-relief cliffs extend seaward beyond the beach and reef flats. Fresh water flow from the beaches and reef flats is small to insignificant. Flank margin Caves are also concentrated in these headlands and are conspicuously absent in the vertical cliffs inland of beach and reef flat areas. The original porosity in the pre-Holocene carbonate rocks of Fais has been rearranged into high-permeability flow systems by repeated exposure to the fresh water lens. The older headlands that extend past the lower permeability beaches and reef flats, conduct water from the lens to the sea. At the same time, flank margin Cave Development between headlands was diminished by the lack of fresh water lens discharge in those areas. A large closed-contour depression containing a fresh water pool looks at first sight like a sinkhole, but is in fact, an ancient well dug into terraced Holocene sands that infill a reentrant in a paleo-sea cliff. The low relative permeability of these sands creates a more substantial fresh water lens than is available
Philippe Audra - One of the best experts on this subject based on the ideXlab platform.
-
relationships between fluvial evolution and karstification related to climatic tectonic and eustatic forcing in temperate regions
Quaternary Science Reviews, 2017Co-Authors: Dominique Harmand, Kathryn Adamson, Gilles Rixhon, Stephane Jaillet, Benoit Losson, Alain Devos, Marc Calvet, Philippe AudraAbstract:This paper reviews the diversity of relationships between river evolution and karstogenesis. It also underlines the fundamental role of numerical dating methods (e.g. cosmogenic nuclides) applied to sedimentary sequences in tiered Cave passages as they have provided new insights into these complex interactions. Although karst terrain is widespread worldwide, we focus on European karst catchments, where the sedimentary records are especially well preserved. We review the recent dating of fluvial sediments and speleothems, to examine the timing of karstification, incision and deposition in Cave levels. The most complete alluvial records occur in tectonically uplifted high mountains where some of the oldest sediment fills date to the Miocene. Evidence indicates that not only uplift, but also climatic conditions and fluvial dynamics (e.g. knickpoint retreat, increased channel flow and/or sediment load, and stream piracies) can play a major role in speleogenesis and geomorphological evolution. In evaporite rocks, speleogenesis is characterized by rapid dissolution and subsidence. In European catchments, gypsum Cave Development largely occurred during cold climate periods, while limestone Caves formed during warm interglacial or interstadial phases. Our synthesis is used to propose four models of fluvial and karst evolution, and highlight perspectives for further research.
-
'Looping Caves' versus 'water table Caves': The role of base-level changes and recharge variations in Cave Development
Geomorphology, 2014Co-Authors: Franci Gabrovšek, Philipp Häuselmann, Philippe AudraAbstract:Abstract The vertical organisation of karst conduit networks has been the focus of speleogenetic studies for more than a century. The four state model of Ford and Ewers (1978), which still is considered as the most general, relates the geometry of Caves to the frequency of permeable fissures. The model suggests that the ‘water table Caves’ are common in areas with high fissure frequency, which is often the case in natural settings. However, in Alpine karst systems, water table Caves are more the exception than the rule. Alpine speleogenesis is influenced by high uplift, valley incision rates and irregular recharge. To study the potential role of these processes for speleogenesis in the dimensions of length and depth, we apply a simple mathematical model based on coupling of flow, dissolution and transport. We assume a master conduit draining the water to the spring at a base level. Incision of the valley triggers evolution of deeper flow pathways, which are initially in a proto-conduit state. The master conduit evolves into a canyon following the valley incision, while the deep pathways evolve towards maturity and tend to capture the water from the master conduits. Two outcomes are possible: a) deep pathways evolve fast enough to capture all the recharge, leaving the master conduit dry; or b) the canyon reaches the level of deep pathways before these evolve to maturity. We introduce the Loop-to-Canyon Ratio (LCR), which predicts which of the two outcomes is more likely to occur in certain settings. Our model is extended to account for transient flow conditions. In the case of an undulating master conduit, floodwater is stored in troughs after the flood retreat. This water seeps through sub-vertical fractures (‘soutirages’) connecting the master conduit with the deep pathways. Therefore, the loops evolve also during the dry season, and the LCR is considerably increased. Although the model is based on several approximations, it leads to some important conclusions for vertical organisation of karst conduit networks and stresses the importance of base-level changes and transient recharge conditions. It therefore gives an explanation of speleogenesis that relies much more on the dynamic nature of water flow than on the static fracture density.
-
The pattern of Caves: controls of epigenic speleogenesis
Géomorphologie : relief processus environnement, 2011Co-Authors: Philippe Audra, Arthur N. PalmerAbstract:Cave Development is related to the geomorphic evolution. Their morphology, preserved far longer than correlative surface features allows reconstructing the regional history of the surrounding landscape. Modeling shows that initial Cave Development occurs along the water table with loops in the phreatic zone along fractures. Consequently, Cave profiles and levels reflect the local base level and its changes. Cave profile is controlled by timing, geological structure, and recharge. In first exposed rocks, juvenile pattern displays steep vadose passages. In perched aquifers, vadose erosion produces large passage along aquiclude. In dammed aquifers, the main drain is established at the water table when recharge is fairly regular. But when irregular recharge causes backflooding, looping profiles develop throughout the epiphreatic zone. Interconnected Cave levels correspond to some of the largest Cave systems in the world. The oldest abandoned highest levels have been dated beyond 3.5 Ma (Mammoth Cave). However, when base level rises, the deepest parts of the karst are flooded; the flow rises along phreatic lifts, and discharges at vauclusian springs. In the epiphreatic zone, floodwater produces looping tubes above the low-flow water table. In such a case of baselevel rise, per ascensum speleogenesis can produce higher-elevation passages that are younger than passages at lower elevations. Base-level rises occur after tectonic subsidence, filling of valleys, or sea-level rise, as for instance around the Mediterranean in response to the Messinian Crisis. Deep-phreatic karst, if not hypogenic, can generally be attributed to flooding by a base-level rise.
-
The role of condensation-corrosion in thermal speleogenesis : study of a hypogenic sulfidic Cave in Aix-les-Bains, France
Acta Carsologica, 2007Co-Authors: Philippe Audra, Fabien Hoblea, Jean-yves Bigot, Jean-claude NobecourtAbstract:Condensation-corrosion is an active speleogenetical process in thermal Caves where high thermal gradient drives air convection. Wall retreat rates are greater than in meteoric Caves. Conversely, evaporation produces depositional processes by replacement of limestone by gypsum and by aerosol decantation leading to the formation of popcorns. The Chevalley Aven belongs to Aix-les-Bains thermal-sulfidic Cave system. Condensation occurs at the contact of cool walls of large spheres ; conversely, evaporation occurs at the output of the narrow passages where the air sinks down from the upper sphere. A weathered layer and biofilms are present where slow condensation occurs. Corrosion distribution varies according to thermal rock conductivity and causes the sphere to develop upwards, laterally, and divergent. This morphodynamic pattern favors the Development of stacked spheres, isolated by narrow necks, and arranged in a bush-like pattern. This Development is clearly active in the vadose zone above the thermal wateer table. We propose that some avens above water table hypogenic Caves, like Villa Luz (Mexico), may be of condensation-corrosion origin instead of phreatic. Future Development will collect physical and chemical data to calculate the condensation-corrosion budget and assess its role in Cave Development.
Campbell S. Nelson - One of the best experts on this subject based on the ideXlab platform.
-
Flank Margin Cave Development in Telogenetic Limestones of New Zealand
Acta Carsologica, 2008Co-Authors: John E. Mylroie, Joan R. Mylroie, Campbell S. NelsonAbstract:Coastal limestone outcrops, typically with advanced levels of diagenetic maturity (i.e., are telogenetic carbonates), were examined on NorthIsland (Raglan Harbour, Kawhia Harbour, Napier, and Waipu Cove) and SouthIsland (Pohara, Paturau River, Punakaiki, Kakanui, and Kaikoura), New Zealand, to determine if flank margin Caves, produced by mixing dissolution, were present. In coastal settings, Caves in carbonate rock can be the outcome of pseudokarst process, primarily wave erosion, as well as karst processes not associated with freshand sea-water mixing suchas epikarst features and conduit-flow stream Caves. Flank margin Caves were successfully differentiated from other Cave types by the following criteria: phreatic dissolutional morphologies at the wall rock and chamber scales; absence of high-velocity, turbulent-flow wall sculpture and sediment deposits; and lack of integration of adjacent Caves into a continuous flow path. The active tectonics of New Zealand creates a variable sea-level situation. The relatively short time of sea-level stability limits the size of the New Zealand flank margin Caves compared to tectonically-stable environments, suchas the Bahamas, where glacioeustasy alone controls sea-level stability. Uplift events can be identified as slow and steady when the flank margin Caves are uniformly elongated in the vertical direction, and episodic when the flank margin Caves show widening and tube development at discrete horizons that cut across rock structure. New Zealand flank margin Caves contain information on uplift duration and rates independent of other commonly used measures, and therefore can provide a calibration to other methods.
-
FLANK MARGIN Cave Development IN TELOGENETIC LIMESTONES OF NEw ZEALAND JAME TIPA "FLANK MARGIN" V TELOGENETSKIH APNENCIH NOVE ZELANDIJE
2008Co-Authors: E Jon, R Joan, Campbell S. NelsonAbstract:UDC 552.54:551.3.051(931) John E. Mylroie, Joan R. Mylroie & Campbell S. Nelson: Flank Margin Cave Development in Telogenetic Limestones of New Zealand Coastal limestone outcrops, typically witadvanced levels of diagenetic maturity (i.e., are telogenetic carbonates), were ex - amined on NortIsland (Raglan Harbour, Kawia Harbour, Napier, and waipu Cove) and SoutIsland (Poara, Paturau River, Punakaiki, Kakanui, and Kaikoura), New Zealand, to de - termine if flank margin Caves, produced by mixing dissolution, were present. In coastal settings, Caves in carbonate rock can be te outcome of pseudokarst process, primarily wave erosion, as well as karst processes not associated witfresand sea-water mixing sucas epikarst features and conduit-flow stream Caves. Flank margin Caves were successfully differentiated from oter Cave types by te following criteria: preatic dissolutional mor - pologies at te wall rock and camber scales; absence ofig �- velocity, turbulent-flow wall sculpture and sediment deposits; and lack of integration of adjacent Caves into a continuous flow pat�. The active tectonics of New Zealand creates a variable sea- level situation. The relatively sort time of sea-level stability lim- its te size of te New Zealand flank margin Caves compared to tectonically-stable environments, sucas te Baamas, were glacioeustasy alone controls sea-level stability. Uplift events can be identified as slow and steady wen te flank margin Caves are uniformly elongated in te vertical direction, and episodic wen te flank margin Caves sow widening and tube develop - ment at discreteorizons tat cut across rock structure. New Zealand flank margin Caves contain information on uplift dura - tion and rates independent of oter commonly used measures, and terefore can provide a calibration to oter metods.
Nenad Buzjak - One of the best experts on this subject based on the ideXlab platform.
-
Flank Margin Cave Development in Carbonate Talus Breccia Facies: An Example from Cres Island, Croatia
Acta Carsologica, 2010Co-Authors: Bojan Otoničar, John E. Mylroie, Nenad Buzjak, Joan R. MylroieAbstract:Plava Grota, Cres Island, Croatia, is a flank margin Cave developed in a coastal setting in talus breccia facies. The internal Cave geometry of small entrances, intersecting adjacent chambers, remnant dissolutional bedrock pillars, and low arches matches diagnostic features used to separate flank margin Caves from epigenic stream Caves on one hand, and sea Caves on the other. Plava Grota is found, along with adjacent smaller Caves, solely in a breccia facies that is most probably of Pleistocene age. This breccia is comprised of clasts derived from diagenetically mature, or telogenetic, Cretaceous carbonate rocks. The clasts are loosely cemented by vadose calcite cements. The breccia facies provide a three-dimensional porosity and permeability structure that behaves hydraulically in a manner similar to the high primary porosity and permeability of young eogenetic carbonate rocks in settings such as the Bahamas or Puerto Rico, and the many flow paths found in highly-tectonized telogenetic carbonate rocks in New Zealand. Plava Grota is the first described flank margin Cave from the coastal carbonate rocks of the Adriatic Sea. According to present sea-level position in relation to the Cave, fresh-water springs in and adjacent to the Cave, general tectonic subsidence of the area and Quaternary eustatic sea-level fluctuations, we propose the hypotheses that the Cave was primarily formed during the MIS 5e sea-level highstand.
-
FLANK MARGIN Cave Development IN CARBONATE TALUS BRECCIA FACIES: AN EXAMPLE FROM CRES ISLAND, CROATIA JAMA TIPA »FLANK MARGIN«, NASTALA V POBOČNI BREČI V OBMOČJU MEŠANJA SLADKE IN SLANE VODE: PRIMER Z OTOKA CRESA NA HRVAŠKEM
2010Co-Authors: Nenad Buzjak, John E. Mylroie, Joan R. MylroieAbstract:Abstract UDC 911.2:551.44(497.5) Bojan Otonicar, Nenad Buzjak, John Mylroie & Joan Mylroie: Flank margin Cave Development in carbonate talus breccia fa-cies: An example from Cres Island, Croatia Plava Grota, Cres Island, Croatia, is a flank margin Cave devel-oped in a coastal setting in talus breccia facies. The internal Cave geometry of small entrances, intersecting adjacent chambers, remnant dissolutional bedrock pillars, and low arches matches diagnostic features used to separate flank margin Caves from epigenic stream Caves on one hand, and sea Caves on the other. Plava Grota is found, along with adjacent smaller Caves, solely in a breccia facies that is most probably of Pleistocene age. This breccia is comprised of clasts derived from diagenetically ma-ture, or telogenetic, Cretaceous carbonate rocks. The clasts are loosely cemented by vadose calcite cements. The breccia facies provide a three-dimensional porosity and permeability struc-ture that behaves hydraulically in a manner similar to the high primary porosity and permeability of young eogenetic carbon-ate rocks in settings such as the Bahamas or Puerto Rico, and the many flow paths found in highly-tectonized telogenetic carbonate rocks in New Zealand. Plava Grota is the first de-scribed flank margin Cave from the coastal carbonate rocks of the Adriatic Sea. According to present sea-level position in rela-tion to the Cave, fresh-water springs in and adjacent to the Cave, general tectonic subsidence of the area and Quaternary eustatic sea-level fluctuations, we propose the hypotheses that the Cave was primarily formed during the MIS 5e sea-level highstand.