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Geology

University of South Florida

2000

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird Dec 2000

Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird

Geology Faculty Publications

Published mechanisms for rift tip propagation at spreading centers include extensional deformation and an initial period of slow spreading. We investigate whether the gravity signal and inferred crustal structure at pseudofaults formed in medium to superfast spreading environments resemble the gravity signal at fracture zones or nontransform discontinuities formed in slow spreading environments. We find that altimetry-based gravity anomalies on the Mathematician, Bauer, Easter, Juan Fernandez, and northern Chile Ridge pseudofaults, located in 75–150 mm/yr (full rate) seafloor spreading environments, are similar in amplitude and form to Atlantic fracture zones with 20–30 mm/yr spreading rates. A 5–15 mGal positive mantle …

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Development, Management And Economy Of Show Caves, Arrigo A. Cigna, Ezio Burri Jan 2000

Development, Management And Economy Of Show Caves, Arrigo A. Cigna, Ezio Burri

International Journal of Speleology

The problems concerning the development of show caves are here considered by taking into account different aspects of the problem. A procedure to carry out an Environmental Impact Assessment (EIA) has been established in the last decade and it is now currently applied. Such an assessment starts with a pre-operational phase to obtain sufficient information on the undisturbed status of a cave to be developed into a show cave. Successively a programme for its development is established with the scope to optimise the intervention on the cave at the condition that its basic environmental parameters are not irreversibly modified. The …

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Verification Of The Causes Of Glaciations And Sea Level Changes Using The Records Of Calcite Speleothems, Y. Shopov, D. Stoykova, L. Tsankov, M. Sanabria, J. Lundberg, L. Georgiev, P. Forti, D. Georgieva Jan 2000

Verification Of The Causes Of Glaciations And Sea Level Changes Using The Records Of Calcite Speleothems, Y. Shopov, D. Stoykova, L. Tsankov, M. Sanabria, J. Lundberg, L. Georgiev, P. Forti, D. Georgieva

International Journal of Speleology

The luminescence of calcite speleothems displays an exponential dependence on soil temperature unless there is a dense cover of forest over the cave to dampen it. This relationship is determined primarily by the strength of solar visible and infrared radiation. It is suggested that, as a consequence, the microzonal variations of luminescence often found in speleothems can be used as a proxy index of Solar Insolation. The luminescence solar insolation proxy record of a speleothem from Jewel Cave, South Dakota, USA, was found to display millenial and centennial cycles in the record. It exhibits a rapid increase in solar insolation …

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Révision De Quelques Hypothèses Sur Le Creusement Karstique, Jacques Choppy Jan 2000

Révision De Quelques Hypothèses Sur Le Creusement Karstique, Jacques Choppy

International Journal of Speleology

Quite often, as we know better karst phenomena and the evolution of the karst environment, several hypotheses on speleogenesis appeared to be flimsy. Some of these hypotheses, concerning processes playing a part in the creation of karst forms, exceed the limits of their field. Others suggest hydraulic mechanisms, and interventions of geological or geographical factors likely to be questioned. Hypotheses relating to the evolution of karst, as well as the classification of karst types, suffer from the lack of an analytical approach. However, some of these hypotheses still have an important place in the current vision of speleologists and karstologists.

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The Influence Of Cave Tourism On Co2 And Temperature In Baiyun Cave, Hebei, China, Linhua Song, Wei Xiaoning, Liang Fuyuan Jan 2000

The Influence Of Cave Tourism On Co2 And Temperature In Baiyun Cave, Hebei, China, Linhua Song, Wei Xiaoning, Liang Fuyuan

International Journal of Speleology

Baiyun Cave in Hebei Province is one of the main show caves in North China. The speleothem landscape is wonderful, but strongly weathered. In order to set up the relationship between visitor flow and CO2 content and temperature, these parameters were measured at observation sites No. 1 and No. 2 in the tourist peak period of May Day Holiday from May 1 to May 7, 2000. and general tourist season August and October, 2000. The results show that visitor flow strongly affects the fluctuations of cave CO2 content and temperature, that the cave topography and dimensions affect the …

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Is It Always Dark In Caves?, Giovanni Badino Jan 2000

Is It Always Dark In Caves?, Giovanni Badino

International Journal of Speleology

Underground natural sources of visible light are considered. The main light producer is Cerenkov radiation emitted in air, water and rock by cosmic ray muons, that depends, in a complex way, on shape of mountain and of caves. In general the illumination increases linearly with the cavity dimensions. Other light sources are from secondary processes generated by radioactive decays in rock from minerals luminescence. The natural light fluxes in caves are in general easy to detect but are not used from underground life.

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New Rare Cave Minerals From The Perolas-Santana Karst System (São Paulo State, Brazil), Paolo Forti, Ermanno Galli, Antonio Rossi Jan 2000

New Rare Cave Minerals From The Perolas-Santana Karst System (São Paulo State, Brazil), Paolo Forti, Ermanno Galli, Antonio Rossi

International Journal of Speleology

The Perolas-Santana karst system (São Paulo State, Brazil) has been partially studied from the mineralogical point of view. The present paper will contribute to the knowledge of the minerals in these caves, describing the occurrence of euhedral celestite crystals and of a rather rare mineral for a cavern environment: lithiophorite. Thanks to these new discoveries the Perolas-Santana karst system becomes one of the most important in Brazil from a mineralogical point of view. Finally, the result of the chemical analyses carried out on this newly discovered Monoxyhydroxide put in evidence a zonation in the distribution of the different elements which …

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