Stratigraphie et Sédimentation au Sud Est de Dôme de Sangiran : l’environnement des Homo erectus au début de Pléistocène Moyen

The Sangiran Dome (Central Java, Indonesia), inscribed on the World Heritage List, is one of the most important sites regarding Homo erectus evolution and regarding hominids’ adaptation to isolated conditions during the Late Lower and Early Middle Pleistocene. Sangiran is a c. 50 sq. km large tectonic ‘boutonnière’ within the Solo depression, whose stratigraphy allows to describe the evolution of the area during the considered period, through the so-called Pucangan, Grenzbank and Kabuh series, influenced by eustatism, volcanism and also orogenesis. Archaeological sites are still rare in the dome, mostly found in the NNW and SSE areas. In the SSE quarter were discovered the oldest artefacts found in Sangiran, the Sangiran 17 Homo erectus fossil (with an almost complete face) and several important archaeological and paleontological sites. Our work focuses on this SSE part of the dome. Its primary objective is to correlate the various sites along a transect defined by the Pucung river between the Dayu and Pucung villages. Cartographic and structural records allow to locate the main sites along a synthetic stratigraphical log, and also to discriminate several structural zones (where the dip varies) linked to the formation of the dome. Our work provides a stratigraphical and structural instrument which is able to help future paleontological and archaeological surveys, allowing to infer the probable location of rich horizons in the topography. A group of stratigraphic sections were identified, recorded and described along the studied transect., in order to relate the evolution of the area between the Late Lower and the Early Middle Pleistocene. Near to the top of the transect, we studied in more details the PCTS site, were several excavation campaigns documented an Early Middle Pleistocene fauna, associated to lithic artifacts (including some using a raw material imported from remote areas) and to several Homo erectus remains. Analyses (granulometry, petrography, mineralogy and taphonomy of tuffaceous pebbles and gravels) helped to precise the deposition environments. This work show that there is little perspective to detail the palaeoclimatic evolution during the considered period in the Pucung area, mostly because of the overwhelming influence of volcanism, much more marked compared to other areas of the dome. It is likely that ‘hot’ volcanic effluients (e.g. volcanic surges) could deposit in the Pucung area. The comparison between the volcanic layers and the alluvial fossil-bearing deposits allows to formulate hypotheses regarding the formation and also the destruction of archaeological occupation layers. Eventually, several facies can be discriminated regarding the Grenzbank, transition zone between the Pucangan and Kabuh series.