title: Laser-induced breakdown spectroscopy for elemental characterization of calcitic alterations on cave walls.
abstract: Cave walls are affected by different kinds of alterations involving preservative issues in the case of ornate caves, in particular regarding the rock art covering the walls. In this context, coralloids correspond to a facies with popcorn-like aspect belonging to the speleothem family, mostly composed of calcium carbonate. The elemental characterization indicates the presence of elements that might be linked to the diagenesis and the expansion of the alterations as demonstrated by prior analyses on stalagmites. In this study, we report the use of laser-induced breakdown spectroscopy (LIBS) to characterize the elemental composition of one coralloid sample with a portable instrument allowing punctual measurements and a laboratory mapping setup delivering elemental images with spatial resolution at the micrometric scale, being particularly attentive to Mg, Sr, and Si identified as elements of interest. The complementarity of both instruments allows the determination of the internal structure of the coralloid. Although a validation based on a reference technique is necessary, LIBS data reveal that the external layer of the coralloid is composed of laminations correlated to variations of the LIBS signal of Si. In addition, an interstitial layer showing high LIBS signals for Fe, Al, and Si is interpreted to be a detrital clay interface between the external and the internal part of the coralloid. These preliminary results sustain a possible formation scenario of the coralloid by migration of the elements from the bedrock.
authors.affiliation: IRAMAT-CRP2A, UMR CNRS 5060, Maison de l'Archéologie, Université Bordeaux Montaigne, Domaine Universitaire, Esplanade des Antilles, 33607, Pessac Cedex, France. lena.bassel@u-bordeaux-montaigne.fr.
authors.forename: Léna
authors.initials: L
authors.lastname: Bassel
authors.affiliation: Institut Lumière Matière, UMR 5306, Université de Lyon 1 - CNRS, Université de Lyon, 69622, Villeurbanne Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Motto-Ros
authors.affiliation: Institut Lumière Matière, UMR 5306, Université de Lyon 1 - CNRS, Université de Lyon, 69622, Villeurbanne Cedex, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Trichard
authors.affiliation: CRITT Matériaux Alsace, 19 rue de St Junien, C. S. 80023, 67305, Schiltigheim, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Pelascini
authors.affiliation: IRAMAT-CRP2A, UMR CNRS 5060, Maison de l'Archéologie, Université Bordeaux Montaigne, Domaine Universitaire, Esplanade des Antilles, 33607, Pessac Cedex, France.
authors.forename: Faten
authors.initials: F
authors.lastname: Ammari
authors.affiliation: IRAMAT-CRP2A, UMR CNRS 5060, Maison de l'Archéologie, Université Bordeaux Montaigne, Domaine Universitaire, Esplanade des Antilles, 33607, Pessac Cedex, France.
authors.forename: Rémy
authors.initials: R
authors.lastname: Chapoulie
authors.affiliation: PACEA, UMR CNRS 5199, Université Bordeaux, Bâtiment B8, Allée Geoffroy Saint Hilaire CS 50023, 33615, Pessac Cedex, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ferrier
authors.affiliation: I2M, UMR CNRS 5295, Université Bordeaux, 33607, Pessac, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Lacanette
authors.affiliation: CELIA, UMR CNRS 5107, Université Bordeaux, 351 Cours de la Libération, F-33405, Talence Cedex, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Bousquet
mesh_terms: D001106:Archaeology; D001154:Art; D002119:Calcium Carbonate; D059552:Caves; D007834:Lasers; D013057:Spectrum Analysis
chemical_list: D002119:Calcium Carbonate
keywords: Alterations; Conservation; LIBS; Laser-induced breakdown spectroscopy; Ornated cave; Speleothems