Datations des cendres volcaniques et analyses géochimiques du remplissage d'Orgnac 3 (Ardèche, France)

Abstract

In the upper levels of Orgnac 3, fresh volcanic ashes trapped in burrows have been discovered allowing the fisson track method of dating to be used on the zircon crystals and which have given an absolute date of 298000 ± 55000 years. The mineralogy of the sediments of the archaeological levels 1 and 2 reveals a sedimentation without an interruption. The geochemical study has revealed a diagenesis of carbonates under the form of concretions and encrustations as well as a diagenesis of calcium phosphates, present in the form of apatite, from bone alteration. We have been able to put into evidence in the upper levels of the infill the formation of a palaeosoil which has resulted from an intense alteration of volcanic minerals.

U-Series and ESR Dating of Teeth from Acheulian and Mousterian Levels at La Micoque (Dordogne, France)

“…On the other hand, the age of the upper layers (L, K and J) seems to correspond with the layers of Orgnac 3 which contain Acheulian and Premousterian industries. Stalagmitic samples at the base of the latter deposits have given an ESR age of 309 34 ka (Falguères et al, 1988) and a mean U-Th age of 339 ka (Shen, 1985), while a fission tracks (TF) age of 298 55 ka was obtained for volcanic ashes trapped at the top of the sequence (Khatib, 1994). Figure 3.…”

Pre-Neandertal behaviour during isotopic stage 9 and the beginning of stage 8. New data concerning fauna and lithics in the different occupation levels of orgnac 3 (Ardèche, South-East France): occupation types

“…Over time, exterior elements, wind transported sands, gradually increased, in relation with the collapsing of the ceiling and the opening up of the entrance of the cave. The effects of run off water are observable, resulting in the deposit of carbonates and the desilicification of flint tools [7,17,18,19]. The layer comprising level 6 (i2) is of heterometric, more or less weathered gravels, in an abundant brownish-red sandy-clay matrix which filled in the spaces between the fallen blocks, some of which 1 m 3 .…”

“…Situated on a plateau near the Rhoˆne Valley, on the righthand shore and to the south of the Arde`che river gorges, the site was excavated from 1959 to 1972 by Jean Combier [6]. The archeological sequence is dated to isotopic stage 9 and the beginning of stage 8 by ESR, U/Th, volcanic minerals and biostratigraphy (Table 1) [8,10,11,12,18,20,25,39]. Biostratigraphical studies (mammal remains, microfauna, fossil pollen) allow to situate the base of the sequence within a temperate context, contemporary with the human occupation and more or less humid according to the levels.…”

Widespread diffusion of technical innovations around 300,000 years ago in Europe as a reflection of anthropological and social transformations? New comparative data from the western Mediterranean sites of Orgnac (France) and Cave dall’Olio (Italy)

“…The archaeological sequence is dated from isotopic stage 9 by ESR, U/Th, (layers 5 and 6) and the beginning of stage 8 by volcanic minerals (from Green clinopyroxene from Mont-Dore-Sancy Volcano) (Shen, 1985;Falguères et al, 1988;Debard, 1988;Debard and Pastre, 1988;Laurent, 1989;Khatib, 1989Khatib, , 1994Masaoudi, 1995). Pre-Neanderthal human remains were discovered in the bottom layers (Lumley, 1981).…”

“…The top of the infilling was probably deposited during a cold and dry phase (Khatib, 1994). The uppermost stratigraphical unit (layers 2 and 1) is mainly characterized by a predominance of species typical of an open landscape (equids and large bovids), and by the replacement of E. mosbachensis by Equus steinheimensis (Forsten and Moigne, 1988).…”