Le karst du gypse des Andes de Mendoza-Neuquen (Argentine), 1992, Salomon J. N. , Bustos R.

THE GYPSUM KARST OF MENDOZA-NEUQUEN (ANDES, ARGENTINA) - Gypsum and anhydrite formations are highly developed in the Andes at the latitude of Santiago (Chile) and Mendoza (Argentina), where they have played a fundamental part in the various stages of the Andes orogeny. After a brief description of the geological background of the cordillera and some information on the main gypsum formations (Tabanos, Auquilco, Huitrin, Papol), the authors deal with the specific climatic context of the high cordillera: a cold and dry atmosphere (high altitude) apparently hardly propitious to the appearance of karstic phenomena. The latter nevertheless do exist and are often well-developed (Pozo de las Animas). They come mainly in the shape of domes and dolines whilst in the bottom of the valley numerous ferruginous crusts are noteworthy. Although the endokarst suffers from the fragility of the rock, a number of caves have developed, some of which are outstanding (Cueva del Leon, 1km).

Observations sur le karst de Bardas Blancas-Malargüe (Andes de Mendoza, Argentine), 1995, Mikkan, R. A.

The karst of Bardas Blancas, situated south of Mendoza province, deve-lops in Jurassic and Cretaceous limes-tones. The continental and semi-arid climate (300 mm/year) is characterized by temperate summers and cold winters. The periglacial processes are actives. The relief presents a semi-karstic morphology: structural landforms ("Schichttreppenkarst" with cuestas) and afew dolines, swallow-holes and pavements. The Los Brujas cave, about 1 000 m long, shows a labyrinthic network (3 siaged levels) with phreatic passages. The impor-tant gypsum speleothems (crusts, flowers) in the lower level and the calcite-opale speleothems indicate an hydrothermal speleogenesis (dissolution by sulfuric acid and gypsum deposit). The actual and active tectogenesis of this region (uphft, hydrothermalism, volcanism) plays an important part in the geomorphological evolution.

Chemical deposits in volcanic caves of Argentina., 1998, Benedetto Carlos, Forti Paolo, Galli Ermanno, Rossi Antonio

During the last Conference of the FEALC (Speleological Federation of Latin America and Caribbean Islands) which was held in the town of Malargue, Mendoza, in February 1997, two volcanic caves not far from that town were visited and sampled for cave mineral studies. The first cave (Cueva del Tigre) opens close to the Llancanelo lake, some 40 kms far from Malargue and it is a classical lava tube. Part of the walls and of the fallen lava blocks are covered by white translucent fibres and grains. The second visited cave is a small tectonic cavity opened on a lava bed some 100 km southward of Malargue. The cave "El Abrigo de el Manzano" is long no more than 10-12 meters with an average width of 3 meters and it hosts several bird nests, the larger of which is characterized by the presence of a relatively thick pale yellow, pale pink flowstone. Small broken or fallen samples of the secondary chemical deposits of both these caves have been collected in order to detect their mineralogical composition. In the present paper the results of the detailed mineralogical analyses carried out on the sampled material are shortly reported. In the Cueva del Tigre lava tube the main detected minerals are Sylvite, Thenardite, Bloedite and Kieserite, all related to the peculiar dry climate of that area. The flowstone of "El Abrigo de el Manzano" consists of a rather complex admixture of several minerals, the large majority of which are phosphates but also sulfates and silicates, not all yet identified. The origin of all these minerals is related to the interaction between bird guano and volcanic rock.