LANS, Benjamin; MAIRE, Richard; QUINIF, Yves; DOUAT, Michel

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Licence d’utilisation du document

LANS, Benjamin
Travaux et recherches archéologiques sur les cultures, les espaces et les sociétés [TRACES]
Department of Anthropology and Archaeology

MAIRE, Richard
Passages

QUINIF, Yves
Service de Géologie Fondamentale et Appliquée

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Communication dans un congrès

Ce document a été publié dans

Proceeding of the 18th UIS Congress - Volume IV - Karstologia Mémoires n°24, Proceeding of the 18th UIS Congress - Volume IV - Karstologia Mémoires n°24, 18th International Congress of Speleology - Savoie Mont Blanc 2022, 2022-07-24, Le Bourget-du-Lac. 2022, vol. 4, p. 170

Résumé en anglais

The Pyrenean Pierre-Saint-Martin/Larra massif presents more than 465 km of surveyed caves. But at the surface of this wellknown karstic mountain area, we can observe "cemeteries" of unroofed and open-air palaeocaves, due to the erosion/dissolution of cretaceous limestones since the Mio-Pliocene. An accurate mapping of these palaeocaves is actually done by remote sensing, in addition to essential field work. Indeed, walls and ground of palaeocaves have not the same micro-topographic characteristics (e.g. roughness) than the surrounding limestone. Those small differences are detected and quantified on the very high-density LIDAR full cover. Moreover, palaeo-speleothems can be detected and localized by the mean of spectral indices analysis, on very high resolution orthophotography and satellite imagery. Some palaeo-galleries have a development of several hundred meters, and show ancient stalagmitic massifs. The first U/Th dating indicate ages older than 400 000 years. An illustration is given by the Lepineux pit, which is extended at the surface by unroofed palaeo-pits, presenting old concretions. Those palaeo-speleothems situated at the surface indicate a pre-ice age, when the entire massif was at a lower elevation, with a forest and a pedologic cover, very favourable to the concretion formation.< Réduire

Origine

Importé de hal

Unités de recherche

Passages - UMR 5319