Biotic versus abiotic calcite formation on prehistoric cave paintings: the Arcy-sur-Cure ‘Grande Grotte’ (Yonne, France) case

Abstract

The ‘Grande Grotte’ cave at Arcy-sur-Cure (Yonne, France) with its prehistoric paintings shows important calcite concretions. Two types of calcite have been observed on the wall: translucent yellowish layers and opaque white or grey layers that completely obstruct the paintings. Other calcite types are present in the lakes of the cave (floating calcite rafts at the surface of the lake and soft calcite at the bottom of the lake).The morphology of the different calcites was observed at different scales by optical microscopy with normal and polarized light, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The elemental composition was measured by using particle-induced X-ray emission (micro-PIXE) and the structure by X-ray diffraction (XRD), infrared (FT-IR) and Raman spectroscopy. The bacterial diversity and its role in calcite formation were assessed by culture and 16S-SSCP in order to distinguish and to assess various abiotic and biotic formation mechanisms.The investigation of calcite characteristics enables conclusions on the formation mechanism and on a biotic or abiotic origin of the calcites. The change of calcite types on the walls reveals changes of the environmental cave parameters. In addition, interactions of calcites with the prehistoric paint layer could be evaluated.

Synchrotron Methods: Color in Paints and Minerals

“…In cave sites, speleothems such as stalagmites and stalactites are important geochronological archives used to trace the archaeological record (Fairchild et al, 2006;Genty et al, 2004;White, 2003). In some rare cases, such speleothems even serve as support for Paleolithic cave art (Chalmin et al, 2007). Flints and obsidians have been frequently encountered either as tools or as raw material for the manufacture of tools.…”

“…Calcium carbonate samples from the wall, from lake sediment, and from film (floating at the surface of the lake like a raft) in the Large cave of Arcy-sur-Cure were studied using a multidisciplinary approach, including microscopic, spectroscopic, microbiological, and molecular biology methods, in order to assess the origin and the possible biogeochemical formation mechanisms of the various calcium carbonates present at the surface of Paleolithic rock art (Chalmin et al, 2007;Reiche et al, 2006a).…”

Synchrotron X-Ray Microanalysis and Imaging of Synthetic Biological Calcium Carbonate in Comparison With Archaeological Samples Originating from the Large Cave of Arcy-sur-Cure (28000-24500 BP, Yonne, France)

“…Two sampling campaigns were carried out to collect calcite near the paintings on the wall (Chalmin et al, 2007). The calcite samples consisted of powders from the yellowish translucent layer, the white and gray opaque layers, and floating calcite from the surface of the lake and the pools.…”

“…Particularly, DNA- and RNA-based molecular surveys are increasingly used to identify the bacterial communities and evaluate the risk of rock art alteration (Zimmermann et al, 2005; Portillo & Gonzalez, 2009; Rusznyak et al, 2012). The precise evaluation of biological impacts on rock art is therefore a highly urgent issue for the Lascaux and Altamira caves (Schabereiter-Gurtner et al, 2002) as well as for the Large cave of Arcy-sur-Cure (Chalmin et al, 2007; Reiche & Chalmin, 2009), where prehistoric figures are completely masked by a white opaque calcite layer, which must be removed to render the prehistoric figures visible. This opaque carbonate layer was assumed to be due to bacterial biomineralization.…”

“…The first identification of bacteria at the origin of the floating calcite in the cave lake of Arcy-sur-Cure was performed several years ago, and these first results demonstrated their calcifying capabilities (Adolphe et al, 1994). More recently, bacterial counting, isolation, and identification were carried out on various calcite samples that cover paints (Chalmin et al, 2007). By means of microbiological analyses, the presence of two genera of bacteria was reported, namely, Pseudomonas and Bacillus spp., which are known for their calcifying capabilities (Adolphe & Billy, 1974).…”