Sedimentological and magnetic study of an alluvial sequence of the upper pleistocene and holocene of adaila wadi (el ma labiod,tebessa, algeria) and palaeoenvironmental indications

摘要

A stratigrapnic, sedimentologlcal and magnetic study was carried out on an alluvial terrace of the EI Ma Labiod plain, in tne North-East of Algeria. This terrace provides a level very rich in archaeological tools belonging to the aterian civilization, older than 35000years. The sedimentological study results show the predominance of the silty fraction followed by fine and coarse sands. Stratigraphically, succession of coarse deposits covered by fine elements corresponds to river levels implemented by contrasted water flow. The cumulative curves have a parabolic-called facies, and demonstrate that the sediment is immature and non-evolved. The magnetic study results are in agreement with the precedents. They reveal a high concentration of magnetic grains in the median part of the stratigraphical section (hearth) and a weak concentration at the base (unité L) (contemporary of a dry climate). The magnetic grains are of variable size (multi-domain, single-domain and superparamagnetic) and are carried by the magnetite and the maghemite of low coercitive force, and also by the goethite and the hematite of strong coercitive force. The magnetic susceptibility curves according to the temperature and the analysis of the IRM acquisition curve (coercivity spectra) confirm these results.