Republished from: Original article
  PDF: /pdf/seka_pdf10280.pdf

Abstract:

Identifying cave levels provides insight into cave development and climatic changes that have affected a karst system over time. Cosmogenic dating has been used to interpret levels in Mammoth Cave and the Cumberland Plateau. This absolute dating technique has proven successful in determining cave paleoclimates and regional geomorphic history, but is expensive. The study presented here is a preliminary method to cosmogenic dating that can outline a region’s speleogenesis using a Geographic Information System (GIS) and published denudation rates. The Carter Cave system in northeastern Kentucky is within the karst landscape found along the western edge of the Appalachians and contains multiple daylighted caves at various elevations along valley walls. These characteristics make the Carter Caves an ideal location to apply GIS to cave level identification and evolution as described by Jacoby et al. (in review), who identified the cave levels within the area. The authors concluded that an argument can be made for either four or five cave levels in the Carter Cave system; however, studies identified four levels in both Mammoth Cave and the Cumberland Plateau. Further analysis indicated that the fifth level formed as a result of a change in lithology rather than an event that influenced the local base level. This research is an extension of the conclusions presented by Jacoby et al. (in review). The GIS was used to calculate the volume of surficial material lost within each level as a result of degradational geomorphic processes. Then, level thickness lost and published denudation rates were used to calculate the relative time required to form each level. There was not one denudation rate applicable to each level within the cave system, but the rates varied between 12 m/Ma and 40 m/Ma. This study concludes that the cave system took between 3.4 and 5.7 Ma to form. This study did not perform an absolute dating of cave sediments or assess any detailed stratigraphic influence.

Republished from: Original article
  PDF: /pdf/seka_pdf10279.pdf

Abstract:

This paper demonstrates the dominant hypogenic origin of caves and other karst features in the Prichernomorsky artesian basin, a major hydrogeological structure of the north Black Sea region. The basin occupies the south of the continental part of Ukraine and the north-central plain part of the Crimea Peninsula and is dominated by the Neogene (lower through middle Miocene) and Paleogene (Eocene through Paleocene) carbonate rocks, intercalated with sands, sandstones, clays and marls. The key study areas, in which some limestone members are exposed and partially drained, lie in the opposed sides of the basin: the north Black Sea region in the continental part (caves in Early Pliocene and Miocene limestones) and the Inner Range of the fore-mountain Crimea in the south, where the basin borders with the fold-trust Alpine mountain region (caves in Eocene and Paleocene limestones). The hypogenic origin of caves is strongly suggested by the analysis of cave morphology and occurrence relative to lithostratigraphy and structural features, cave sediments, isotopic and mineralogical data, and paleohydrogeological analysis. Despite of differences in age and diagenetic maturity of the host rocks, the caves demonstrate remarkable common features imposed by their common origin. The hypogenic speleogenetic model well explains observed specific hydrogeological and geochemical features of the regional multi-storey aquifer system in the central confined part of the basin. Hypogene speleogenesis is likely to play a role in the formation of carbonate-hosted reservoirs, as well as in the migration and accumulation of hydrocarbons in the Prichernomorsky basin.

Republished from: Davis, R. L., and Gamble, D. W., eds., 2006, Proceedings of the 12th Symposium on the Geology of the Bahamas and Other Carbonate Regions, p. 88-99
  PDF: /pdf/seka_pdf9854.pdf

Abstract:

Coastal Quintana Roo, Mexico, including islands such as Cozumel and Isla Mujeres, contains numerous ridges of Quaternary eolian calcarenite in two packages, one Pleistocene and one Holocene. The Pleistocene eolianites are recognizable in the field by well-developed terra rossa paleosol and micritic crust on the surface, containing a fossil epikarst. The foreset beds of these eolianites commonly dip below modern sea level, and fossilized plant root structures are abundant. The Holocene
eolianites lack a well-developed epikarst, and have a calcernite protosol on their surfaces. The degree of cementation, and the grain composition, are not reliable indicators of the age of Quaternary eolianites.

The Pleistocene eolianites have been previously described (e.g. Ward, 1997) as exclusively regressive-phase eolianites, formed by the regression during the oxygen isotope substages (OIS) 5a and 5c. However, certain eolianites, such as those at Playa Copal, contain flank margin caves, dissolution chambers that form by sea water/fresh water mixing in the fresh-water lens. For such mixing dissolution to occur, the eolianite must already be present. As the flank margin caves are found at elevations of 2-6 m above current sea level, the caves must have developed during the last interglacial sea-level highstand, and the eolianites could not have formed on the regression from that or younger highstands. Therefore the eolianites must be transgressive-phase
eolianites developed at the beginning of the last interglacial sea-level highstand, or either transgressive- or regressive-phase eolianites from a previous sea-level highstand that occurred earlier in the Pleistocene. There is no field evidence of oxygen isotope substage 5c or 5a eolianites as suggested by Ward (1997).

Most coastal outcrops show classic regressive–phase Pleistocene eolianites as illustrated by complex and well-developed terra rossa paleosols and epikarst, and dense arrays of fossilized plant roots. However, in addition to flank margin caves, other evidence of transgressive-phase eolianites includes notches in eolianites on the west side of Cozumel, with subtidal marine facies onlapping the notches. The absence of a paleosol between those two units indicates that the eolianite is a transgressive-phase deposit from the last interglacial. All Holocene eolianites are, by definition, transgressive-phase units.

Republished from: Martin, R. and Panuska, B., eds., 2004, Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions, Gerace Research Center, San Salvador Island, Bahamas, p. 145-155
  PDF: /pdf/seka_pdf9855.pdf

Abstract:

The landforms of San Salvador, Bahamas, demonstrate extensive karst development, in particular epikarst features called pit caves. Studies on Hog Cay, an interior dune ridge located north of the San Salvador International Airport runway, indicate that some pit caves have morphologies controlled by bedding. These pit caves, initiating within the vadose zone, have a tendency to follow the foreset beds of the dune for some distance and are analogous to solution chimneys found in continental settings. These solution chimneys are distinguished from vertical shafts, which propagate vertically into the vadose zone of the
subsurface with little, if any, horizontal offset.

Previous field observations have described how eolian deposits can be sorted by grain size into alternating coarse-grained and fine-grained strata. The alternating strata undergo selective cementation, where the coarse-grained strata become poorlycemented and the fine-grained strata become well-cemented because of retention of pore waters. This is observed in weathered outcrops as poorly-cemented micro-recesses and well-cemented micro-ledges. In the subsurface, the coarse-grained, poorlycemented strata are the preferred flow path for vadose water. This water is perched upon and flows laterally along the foreset beds on the well-cemented, fine-grained strata. Pit caves forming under these conditions are described as solution chimneys. Also found on Hog Cay are pit caves that extend from the surface down to near sea level. These vertical shafts are generally found on the crests of dunes, with the deepest shaft being over 15 meters. They commonly display a near-perfect cylindrical shape and extend vertically with no horizontal offset. The walls of vertical shafts exhibit micro-ledge and micro-recess morphology; however, the vertical shafts have no indication of bedding control, which may be due to cementation in the fine-grained layers
being less complete in certain areas, facilitating vertical shaft development.

Preliminary XRD analysis of the pit caves shows that the top and bottom wall rocks of one pit is almost entirely calcite, but the wall rocks in the middle of the pit have a high aragonite content. These observations are consistent with long residence time of meteoric water in the epikarst at the top of the pits, and in the fill material at the base of the pits, such that aragonite was inverted to calcite. However, the rapid transit time of the vadose water along the pit walls allowed dissolution to enlarge the pit, but without inversion of the primary aragonite.

  PDF: /pdf/seka_pdf9853.pdf

Abstract:

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 elsewhere on the island.

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January 24, 2020

The 16th Sinkhole Conference: Register and Help the People of Puerto Rico!

in Miscellaneous by Super User
As written at the top of this news message, our friends in Puerto Rico have told us that the best way you can help the people of the island recover is go to Puerto Rico. We hope you register for the Sinkhole Conference, not simply because we believe it will be a great experience for you, but also because we truly believe it will help these people who have suffered greatly from natural tragedies over the past few years. If you register now and wish to give a presentation, you still have the opportunity. Sign up for Karst Clips, a lightning talk-style session where you can update everyone on…
January 24, 2020

Call for the 2020 EuroSpeleo Protection Label

in Miscellaneous by News Manager
Dear Caving Friends, The European Speleological Federation (FSE) and its European Cave Protection Commission (ECPC) is very pleased to announce the launching of the 2020 Call for the EuroSpeleo Protection Label. Please find enclosed the application form (deadline for applications 15 June 2020). You can also find the application form on the FSE website: http://www.eurospeleo.eu/en/commissions-en/cave-protection/ecpc-activities/eurospeleo-protection-label.html The aim of the EuroSpeleo Protection Label is to support active cave protection in the speleo clubs, committees, national commissions,…