Republished from: Original article
  PDF: /pdf/seka_pdf11251.pdf

Abstract:

A statistical model of karstic flow conduits, based on statistical physics of random walks, is developed. It allows us to compute the mean depth of flow conduits versus the distance from the inlet and versus the dip. It provides results that are in good qualitative agreement with previous results of other authors: the mean depth increases, slowly, with the distance, and it increases, not in a regular fashion, with the dip. The variability of the depth of the conduits, possibly leading to some conduits far from the water table, and the fact that well developed conduits are scarce or not, is linked to the probability of exploitation of the different fractures, the potentially permeable bedding planes, faults and joints in the karstifiable rock. On the basis of this result, we propose that interesting cavities - from the point of view of caving and cave diving - are found only in a small range of those exploitation probabilities. Finally, we emphasize the non-euclidean properties of flow conduits; especially, that many shortest pathways may exist and that a straight line is not usually the shortest pathway that actually develops between inlet and outlet.

Republished from: Original article
  PDF: /pdf/seka_pdf10838.pdf

Abstract:

The petrographic, isotopic and chemical changes occurring around 8.2 ka in two stalagmites, one from the Père Noël cave (Han-sur-lesse, Belgium) and one from the Hotton cave (nearby Marche-en-Famenne, Belgium) are presented. The Père Noël stalagmite presents a particularly dense grey compact calcite around 8.2 ka, while the Hotton stalagmite presents a deposition hiatus of ca 1100 years.Besides the macroscopic aspect of the stalagmites, changes in their isotopic (δ18O and δ13С) composition and in their chemical (Sr/Ca, Mg/Ca) composition are observed. Regarding the early start and the duration of the climate deterioration, it is impossible to link the onset of the observed wet phase in the studied speleothems as directly related to the so-called 8.2 ka event. The question arises if the climate deterioration around 8.2 ka observed in both stalagmites is one among other deteriorations occurring during the early Holocene.

Republished from: Original article
  PDF: /pdf/seka_pdf13268.pdf

Abstract:

At the western shores of Messinian Mani Peninsula in South Greece, the composite, integrated karstic system of ‘‘Selinitsa’’ cave and ‘‘Drakos’’ underground river is developed above and below sea-level respectively, in the medium-bedded limestones of the Mani geotectonic unit. The formation and the development of these caves started, most likely, during Middle Pleistocene. Initially, these caves were terrestrial and developed separately. They were connected probably during Holocene through a fi ssure. The development of this united karstic system is controlled by tectonics. ‘‘Selinitsa’’ cave is older than ‘‘Drakos’’. The sequential base levels of karstifi cation demonstrate the continuous sea-level changes during Pleistocene and Holocene, induced by the relative tectonic activity. This united karstic system is characterized by ‘incomplete linkage’ to the sea.

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in Miscellaneous by Super User
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in Miscellaneous by News Manager
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