TAK-Online
Contents and Abstracts
Racovita, G., Boghean, V. & Petrescu, M. Le bilan topoclimatique de la Grotte de Closani (Monts Mehedinti, Roumanie). pp. 7–86.
Synthèse des données portant sur la thermométrie et l'hygrométrie de l'atmosphère, la thermométrie des substratums calcaires et l'évapo-condensation souterraine, obtenues durant deux cycles annuels de mesures. La distribution spatiale des valeurs moyennes des divers paramètres topoclimatiques, ainsi que l'amortissement de leurs variations à l'intérieur de la grotte sont analysées par des modèles résultant de l'adaptation des courbes fonctionnelles. Les conclusions relèvent les particularités topoclimatiques de la cavité, auxquelles s'ajoutent quelques considérations sur la signification qu'on peut attacher à ces modèles.
TAK Articles
Forti, P. Benedetto, C. & Costa, G. Las Brujas Cave (Malargue, Argentina): An example of the oil pools control on the speleogenesis. pp. 87–94.
The influence of the oil pools and their fluids over the speleogenesis of limestone areas was proposed only recently for the region of the Guadalupe Mountains (New Mexico).
A new demonstration of this has been found in the Las Brujas cave (Malargue, Mendoza Province, Argentina), which is the most famous and the only partially prepared for the tourism in the country. The organization of a joint-program between the Italian Speleological Society and the Argentina Institute of Speleological Research made the scientific exploration of this cave possible.
Thanks to the detailed morphological analyses of the hosted speleothems and cave minerals it was possible to reconstruct the complex speleogenetic evolution the cave underwent, which started with the upwelling of fluids full of hydrogen sulphide from an oil pool. In the present paper, after a short geographic and geolithologic sketch of the karst area, the speleogenetic steps for the Las Brujas cave are presented and discussed.
Diaconu, G. Accolements réguliers des cristaux de calcite du milieu spéléal. pp. 95–100.
L'auteur présente un point de vue suivant lequel l'accolement régulier est une particularité cristalo-géométrique qui peut résulter dans le processus de croissance des cristaux sans égard que les individus ainsi associés ont la même composition chimique ou bien des compositions chimiques différentes.
Istvan, D. & Damian, S., G. Regular rhombohedric calcite crystals intergrowths in the cave „Pestera Cristalelor din Valea Rea“ (Rodnei Mountains, Romania). pp. 101–106.
In a small cave carved in the metamorphic limestones of Piatra Rea, a whole section of the passage walls and ceiling, about 13 m long, is covered with quasi-parallel calcite crystals, up to 10-12 cm long and 2 cm thick. Crystallographic, microscopic, DTA, X-ray and spectral quantitative investigations strongly suggest a vug-type genesis. The last crystallization sequences display temporary air-rich episodes and, finally, seepage and dripping crusts witness for full-air conditions. The paragenesis which resulted from this last stage of crystallization (calcite, aragonite, strontianite, dolomite, pyrite) suggests a special chemistry of the solutions (also confirmed by the spectral analyses) and probably, a higher temperature. Calcite crystals intergrowths developed under specific conditions, which had evolved from a closed space to an aerial environment during long periods of time, in which changes of the solutions chemical composition and temperature had occurred.
Ghergari, L., Onac, B., P. & Sântamarian, A. Mineralogy of moonmilk formation in Romanian and Norwegian caves. pp. 107–120.
Ten different moonmilk samples collected in nine caves from Romania and Norway were analysed in order to define their mineralogical and crystallographical features. Using transmission polarizing microscopy, X-ray, SEM and TEM techniques we identified the following crystals' morphologies: fibrous, acicular, prismatic and fibrous-lamellar; these were ascribed to two different situations: calcite pseudomorphosis after aragonite or vaterite (possible) and calcite paramorphosis after monohydrocalcite.
A ternary system to diagnose various types of moonmilk is proposed.
Roata, S. Depositional processes in active caves of the Sureanu Mountains (the Southern Carpathians, Romania). pp. 121–128.
The study is concerned with a detailed analysis of sediments from four active caves of the Sureanu Mountains. The influence of the morphology on the hydrodynamic features of the underground rivers is also stated. Consequently, three types of active caves were distinguished: tunnel caves (Pestera Bolii), semiopen caves (Sura Mare) and closed caves (Gaura Frântoanei, Pestera lui Cocolbea).
Horoi, V. Sedimentological studies in Racovita Gallery–Topolnita Cave (Mehedinti Plateau, Romania). An evolutive interpretation. pp. 129–144.
Mineralogical, granulometric and sequential analyses were performed on the infilling deposits preserved in the most important fossil gallery in Topolnita Cave - Racovitã Gallery.
Two evolutive cycles have been outlined, corresponding to a single stage of hydrologic activity. During this period, the external changes in climate and geomorphology controlled the succession of the erosion, accumulation and chemical precipitation phases.
Stoica, R. Karst phenomena in the Plain of Danube (Romania). pp. 145–151.
One of the geodynamic effects of the earthquake dated March 4, 1977, generally little known, although it is very dangerous for the stability of constructions, was the earth-falls identified in the southern part of Giurgiu town, due to the sudden flow of a great volume of sandy materials from the alluvial deposit into the karstic cavities of the subjacent limestone formations.
The paper presents the results of geological, hydrogeological and geophysical surveys performed by ISPIF-SA on the platform of Giurgiu Chemical Plant, where a sinkhole of large dimensions occurred, the mechanism of this complex phenomenon, similar activities in other countries and anti-karst measures to protect the constructions located in areas with such a potential.
Prohaska, S. & Stevanovic, Z. The development of autocross-regression model for karst springflow simulation. pp. 151–154.
The coefficients of a linear regression between the flowrates of the karst spring „Nemanja 2“, considered as an output, and the same flowrates and the rainfall, taken as input functions, were computed. The agreement between the reconstructed history of the spring flowrates and the actually recorded values is achieved within a standard estimation error of about 75% of the spring mean annual discharge.
Mitrofan, H., Tudor, M. & Trufas, V. A correlative analysis of the discharge history of the Sura Mare swallet - resurgence karst system (Romania). pp. 155–162.
Conventional signal analysis has been performed on the flowrate histories of a karst outlet and of its major swallet, which provides about half of the discharged water volume.
Both the swallet, supplied by a crystalline rocks aquifer, and the karstic outlet, display a similar behavior: poor correlation with the rainfall history and important autocorrelation, extended over more than 10 days. Moreover, the simultaneous swallet and outlet flowrates are very close correlated.
A possible explanation for this „porous aquifer“ behaviour of the karst system may be a sandstone layer, „trapped“ between two limestone stacks: an upper one, exposed to direct infiltration, and a lower one, which hosts the major cave stream passage.
Tenu, A. & Davidescu, F. Relations entre le Lac Techirghiol (Dobroudja du Sud, Roumanie) et les aquifères adjacents. pp. 163–174.
Le lac Techirghiol représente, par les qualités de ses eaux et de la boue, une des plus importantes bases de traitement de la Roumanie.
En commençant par l'année 1970, on a constaté une augmentation continue du niveau de l'eau dans le lac, en parallèle avec une diminution de la salinité et des effets défavorables sur la capacité de régénération de la boue thérapeutique.
L'identification des causes du déséquilibre mentionnée et la conservation de l'ensemble des conditions initiales rendent nécessaire la connaisance détaillée géologique, hydrologique et hydrogéologique de la zone dans l'ensemble ainsi que les interrelations du lac avec des divers facteurs modifiants, naturels ou artificiels.
Un tel ensemble de connaissances peut être finalement structuré dans un modèle conceptuel vaste qui doit constituer la base d'une future modélisation numérique quantitative.
Le modèle présenté par les auteurs est basé non seulement sur des observations de terrain mais aussi sur quelques centaines d'analyses concernant les paramètres physico-chimiques (conductivité spécifique * dens., etc.) et surtout isotopiques (18O, D,14C, 3H) effectuées dans tous les types d'eau de la zone.
Oraseanu, I. Hydrogeological regional classification of the Romanian karst. pp. 175–180.
Hydrogeological features of the Romanian karst are specific for each of the main geo-structural units of the country. Such differences, supported by field data, conduct the author to distinguish four hydrogeologic types of karst: Carpathian Orogen karst type, North Dobrogea karst type, platform karst type and post-tectonic Carpathians' cover karst type.
Povara, I. & Horoi, V. Morpho-hydrographic and hydrogeologic observations in the limestone area from the south-eastern Metaliferi Mountains (Romania). pp. 181–188.
The results of the preliminary research performed on a karstic area from Metaliferi Mountains are described. The exo- karstic morphology, the underground drainages and the chemistry of two low TDS springs, one of which is hypothermal (22.8 deg C), are discussed. A convective cell, developed in a normal heat-flow environment, is considered as a possible explanation for the recorded spring temperature.
Feru, M., U. Considérations sur la genèse et la circulation des eaux thermominérales karstiques de la zone de Mangalia (Roumanie). pp. 189–198.
A partir du fait que les eaux thermominérales de Mangalia sont des eaux sulfureuses (H2S = 1,5 - 11 mg/l), chlorosodiques, bromoiodurées, à minéralisation réduite (1,0 - 1,4 g/l), dont la composition chimique ne peut être expliquée par la circulation dans des roches carbonatées, il faut admettre l'existence d'au moins deux composantes: l'une minéralisante, constituée par des eaux de gisement à concentration élevée, provenant éventuellement d'en dehors du système karstique, qui sont accompagnées sans exception par des gaz libres méthaniques, dont l'accès vers la surface doit être mis en rapport avec une faille de profondeur et une autre, diluante, à caractère bicarbonaté, magnésien, calcique et à minéralisation réduite, au dessous de 1 g/l, qui caractérise les eaux à circulation karstique.
Les recherches isotopiques sur les eaux souterraines des formations calcaires de la Dobroudja Méridionale et l'étude de la concentration en deutérium de ces eaux ont prouvé que l'aire d'alimentation de ce dernier type d'eau doit être située du côté de la Plate-forme Prébalcanique; la nappe aquifère accumulée dans les calcaires sarmatiens est alimentée aussi par les eaux d'infiltration locale.
Quant à l'hydrogène sulfuré, il faut remarquer que c'est un gaz habituel dans les eaux de gisement et qu'il est un résultat de la réduction des sulfates contenus dans les eaux, par des bactéries anaérobies spécifiques, en présence de certaines matières organiques (dans ce cas, le méthane).
Radulescu, C. & Samson, P., M. Dental morphology of the Mimomys/Arvicola transition forms. pp. 199–206.
On the basis of dental material coming from a Middle Pleistocene chronological succesion of three karst deposits (Gura Dobrogei - 4 rock-shelter, lower level, Casian Cave and Gura Dobrogei Cave - phase 1) of Central Dobrogea, Romania, a gradual transition from Mimomys intermedius to Arvicola cantianus is presented corresponding to a shift from rhizodont to arhizodont condition. The evolutionary process is distinguished by the reduction of the roots and their very late formation in cheek-teeth characterized by increasing hypsodonty.
Codrea, V. & Czier, Z. Preliminary data concerning the big mammalian fauna from the Subpiatrã Pleistocene deposits, Bihor County (Romania). pp. 207–210.
On the occasion of some customary dynamiting activities, performed in June 1989 at the limestone quarry which supplies the Enterprise for Cement from Alesd, a series of breccia fragments containing vertebrate bones could be noticed. Thus, it was discovered that the explosion destroyed a small, probably filled up, pot-hole. the following taxa have been identified there up to the present: Carnivora - Ursus deningeri von Reichenau, Meles sp. (?thorali Viret); Proboscidea - an elephant with trogontheroid features; Perissodactyla - Equus sp. (big size), Dicerorhinus etruscus brachycephalus (Schroeder); Artiodactyla - cf. Praealces latifrons (Johnson), Capreolus capreolus süssenbornensis (Kahlke), Cervus sp. (elaphus size), Caprinae indet., Bison cf. priscus Bojanus, Sus scrofa Linné. A list of micromammals (Venczel, 1990) can be added to the big mammalian fauna. The elements already discovered suggest the MmQ - 3b biozone (Agusti et al., 1987).
Short Notes
Todor, V., Giurgiu, I. & Silvasanu, G. L'analyse quantitative de quelques spéléothèmes et échantillons de la grotte en sel 6S de Mînzalesti (Subcarpathes de Vrancea - Roumanie). pp. 211–212.
Kessler, E. & Venczel, M. Quaternary vertebrate remains from Emirkaya-2, Turkey. pp. 213–216.