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Retour de manivelle. Quelle place pour les outils et machines dans l'étude et la valorisation du patrimoine industriel ? Les bâtiments-machines (en Occitanie) The building-machines (in Occitanie

The Piei mine-cave (Lagnes, Vaucluse, France), a hypogene iron-ore paléokarst. The Piei mine-cave is siutated at the contact of the Vaucluse Mounts and the Carpentras basin, close to the Fontaine de Vaucluse spring. It develops in Cretaceous limestone (urgonian fades) on a main regional lineament, the Salorl-Cavaillon fault. The cave was mined in the 19th Century, giving access to passages previously completely filled with diverse neogene sands and massive iron crusts. The miners mainly followed the natural passages. The origin of the cave is related to hypogenic flow rising along deep fissures or hydraulic breccia pipes, depositing iron at the contact or on top of the neogene sand fillings. Microbial activity was present during that time, and is associated to the iron deposition. This cave probably was active in the Neogene, when the Vaucluse plateau was uplifted. The Piei mine-cave records the position of the corresponding base level and thus the progressive tilting of the plateau, as do other similar caves located around the western edge of the Vaucluse Plateau.

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Abstract:Although underground dinosaur tracksites inside anthropic cavities such as mines or tunnels are well-known throughout the world, footprints inside natural karstic caves remain extremely rare. The Malaval Cave (Lozère, southern France) is well-known by speleologists for the abundance and the exceptional quality of acicular and helictite aragonite speleothems. Recent palaeontological prospecting inside this cave allowed the discovery of tridactyl dinosaur tracks.Here, a detailed study of theropod footprints was for the first time conducted inside a natural karstic cave, using photogrammetric imaging technique. Tracks from the Malaval Cave are located inside the "Super-Blanches" galleries. More than 26 footprints were identified. They are Hettangian in age (Lower Jurassic) and preserved as both in situ convex hyporeliefs and ex situ concave epireliefs. Tree morphotypes are distinguished, (i) "DilophosauripusKayentapus" morphotype, (ii) "Eubrontes" morphotype, and (iii) "Grallatorid" morphotype. Sedimentological and mineralogical analyses of the tracksite indicate that the depositional environment varied from periodically emergent subtidal to intertidal/supratidal flat marsh. This work highlights the great interest and importance of palaeoichnological prospecting in karst caves. This is particularly true for the Causses Basin where hundreds of natural cavities were reported by speleologists in the formations yielding dinosaur traces.