Le site paléolithique de Chez-Pinaud 1 (Charente-Maritime, France) : lithostratigraphie, processus de formation, approche taphonomique - Archive ouverte HAL
Article Dans Une Revue PALEO : Revue d'Archéologie Préhistorique Année : 2023

Le site paléolithique de Chez-Pinaud 1 (Charente-Maritime, France) : lithostratigraphie, processus de formation, approche taphonomique

Résumé

The Palaeolithic site of Chez-Pinaud 1 yields several Mousterian layers and some Aurignacian pieces. It has been the purpose of several campaigns of excavation. Geologic works exposed hereafter were achieved in the context of excavations carried out by J. Jaubert and J.-J. Hublin between 2004 and 2007. They aimed 1) to establish the lithostratigraphy of the site, 2) to characterize sedimentary and diagenetic processes involved in the genesis of deposits and, 3) to define palaeoenvironments contemporaneous with this sedimentary series. Methods used for this approach were mainly descriptive and were completed by sedimentological analysis: granulometry, micromorphology, determination of organic carbon content. On the grounds of geological results, a tentative global taphonomic approach of archaeological layers has been achieved. It has been completed by a detailed and quantified analysis of archaeological layers contained in the deepest lithostratigraphic unit of the site (unit 5). This study was performed in the context of excavations conducted by W. Rendu since 2019. It has implied analysis exclusively applied on archaeological remains (artefacts, bones): fabric analysis, granulometry of the lithic remains, research of specific organizations. The site of Chez-Pinaud 1 is located near the small town of Jonzac (SW France), in the upstream part of the valley of the Seugne river, which is a left-hand tributary of the Charente river. This part of the valley, SE-NW oriented, runs parallelly to the axis of anticlinal of Jonzac. It is carved in Coniacian and Turonian limestones, which display a very variable texture: grainstone, packstone, mudstone. It exhibits a quite specific morphology: rather wide in its middle part (about 500 m), it is partially barred upstream and downstream by two rocky spurs 1,5 km apart. The site is situated in the middle part of this geomorphological system (fig. 1), on the right side of the river, between 5 and 10 m above the low water level, which is measured here at 32 m of absolute elevation. The plateau, which dominates the site is capped by brown clayey sands that relate to the “Complexe des Doucins”. The layers of archaeological remains are buried in thick slope deposits, which overlie alluvium found by boring. These are related to a former bed of the Seugne river. Sections made during excavations have allowed the lithostratigraphy of this sedimentary series (fig. 2) to be established and seven successive morphogenetic phases to be identified. The oldest refers to the deposition of unit 5 and dates from the MIS 4. Sedimentation is then dominated by solifluction and runoff in a cold periglacial context. Such climatic conditions have locally led to the formation of small sorted polygons. Taphonomic analyses show that Mousterian layers contained in these deposits have suffered only weak modifications, what allows a reliable archaeozoological and technological approach of archaeological assemblages to be achieved. Nevertheless, very locally, in small gullies, only the heaviest remains are preserved. The next morphogenetic phase occurs at around the transition between the MIS 4 and 3. It corresponds to a widespread erosion of the surface of accumulation and probably results from a change in the local base level, i.e. the Seugne river. This change can correspond to a slight incision of the stream in its valley, or to a lateral northward migration of the river that has caused the undercutting of the downslope part of deposits. At the beginning of MIS 3 occurs a new accretion phase (deposition of unit 4), which is the result of several dynamic processes: breakdown of the next calcareous rockwall, solifluction, probably of stone-banked type, and runoff locally of high competency. Importance of movings (several meters) suffered by some sedimentary elements, suggests that Mousterian levels contained in these deposits have undergone deep modifications and probably some mixing. The next sedimentary episode (deposition of unit 3) is dominated by runoff associated to small mudflows. It happens during the second half of MIS 3 (presence of some rare Aurignacian tools). The last accretion phase (deposition of unit 2) is the result of niveo-eolian phenomena in a very cold and arid environment. Probably contemporaneous with the formation of a large sand wedge identified in the neighboring site of Chez-Pinaud 2, it could date from the end of MIS 3 or the beginning of MIS 2. Finally, with the onset of the temperate oceanic Holocene climate, a luvisol develops on the upper part of the sequence. Consecutively to a recent hill side cultivation, it has been for the most part truncated and a cumulic organo-mineral horizon settled (unit 1).
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Dates et versions

hal-04701861 , version 1 (18-09-2024)

Identifiants

  • HAL Id : hal-04701861 , version 1

Citer

Jean-Pierre Texier, Marc Thomas. Le site paléolithique de Chez-Pinaud 1 (Charente-Maritime, France) : lithostratigraphie, processus de formation, approche taphonomique. PALEO : Revue d'Archéologie Préhistorique, 2023, 33, https://journals.openedition.org/paleo/9338#quotation. ⟨hal-04701861⟩
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