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UDC 551.435.8:551.3.053(44) Philippe Audra, Fabien Hoblea, Jean-Yves Bigot & Jean-Claude Nobecourt: The role of condensation corrosion in thermal speleogenesis. Study of a hypogenic sulfidic cave in Aixles-Bains, France Condensation-corrosion is an active speleogenetical process in thermal caves where high thermal gradient drives air convection. Wall retreat rates are greater than in meteoric caves. Conversely, evaporation produces depositional processes by replacement of limestone by gypsum and by aerosol decantation leading to the formation of popcorns. The Chevalley Aven belongs to Aix-les-Bains thermal-sulfidic cave system. Condensation occurs at the contact of cool walls of large spheres; conversely, evaporation occurs at the output of the narrow passages where the air sinks down from the upper sphere. A weathered layer and biofilms are present where slow condensation occurs. Corrosion distribution varies according to thermal rock conductivity and causes the sphere to develop upwards, laterally, and divergent. This morphodynamic pattern favors the development of stacked spheres, isolated by narrow necks, and arranged in a bush-like pattern. This development is clearly active in the vadose zone above the thermal water table. We propose that some avens above water table hypogenic caves, like Villa Luz (Mexico), may be of condensation-corrosion origin instead of phreatic. future development will collect physical and chemical data to calculate the condensation-corrosion budget and assess its role in cave development.

UDC 551. 435.84(234.3) Philippe Audra, Alfredo Bini, Franci Gabrovšek, Philipp Häuselmann, Fabien Hobléa, Pierre-Yves Jeannin, Jurij Kunaver, Michel Monbaron, France Šušteršič, Paola Tognini, Hubert Trimmel & Andres Wildberger: Cave and Karst evolution in the Alps and their relation to paleoclimate and paleotopography Progress in the understanding of cave genesis processes, as well as the intensive research carried out in the Alps during the last decades, permit to summarize the latest knowledge about Alpine caves. The phreatic parts of cave systems develop close to the karst water table, which depends on the spring position, which in turn is generally related to the valley bottom. Thus, caves are directly linked with the geomorphic evolution of the surface and reflect valley deepening. The sediments deposited in the caves help to reconstruct the morphologic succession and the paleoclimatic evolution. Moreover, they are the only means to date the caves and thus the landscape evolution. Caves appear as soon as there is an emersion of limestone from the sea and a water table gradient. Mesozoic and early tertiary paleokarsts within the alpine range prove of these ancient emersions. Hydrothermal karst seems to be more widespread than previously Ta temeljijo na sintezi novih dognanj o procesih speleogeneze in rezultatih intenzivnih terenskih raziskav v Alpah v zadnjih desetletjih. Razvoj freatičnih delov jamskih sistemov poteka v bližini freatične površine, ki je vezana na položaj izvirov, ti pa so vezani na dno alpskih dolin. Torej je razvoj jam neposredno vezan na geomorfološki razvoj terena in poglabljanje dolin. Jamski sedimenti nosijo informacijo o zaporedju morfoloških in klimatskih dogodkov. Še več, določanje starosti jam in poteka razvoja površja, je možno edino z datacijo jamskih sedimentov. Razvoj jam se začne ob emerziji apnenca in vzpostavitvi hidravličnega gradienta. Mezocojski in zgodnje terciarni paleokras v območju Alp so dokaz starih emerzij. Hidrotermalni kras je očitno bolj razširjen, kot so domnevali v preteklosti. Te jame so bile pozneje preoblikovane z meteorno vodo, ki je zabrisala sledi zgodnjega hipogenega zakrasevanja. Ledeniki zavi-TIME in KARST -2007 54 presumed. This is mostly due to the fact that usually, hydrothermal caves are later reused (and reshaped) by meteoric waters. Rock-ghost weathering is described as a new cave genesis agent. On the contrary, glaciers hinder cave genesis processes and fill caves. They mainly influence cave genesis indirectly by valley deepening and abrasion of the caprock. All present datings suggest that many alpine caves (excluding paleokarst) are of Pliocene or even Miocene age. Progress in dating methods (mainly the recent evolution with cosmogenic nuclides) should permit, in the near future, to date not only Pleistocene, but also Pliocene cave sediments absolutely. Key Words: Karst, Cave genesis, Alps, Glaciations, Messinian event, Paleoclimate, Paleotopography. rajo procese speleogeneze in zapolnjujejo jame. Na razvoj jam vplivajo posredno, p...

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