Geoarchaeological alluvial terrace system in Tarazona: Chronostratigraphical transition of Mode 2 to Mode 3 during the middle-upper pleistocene in the Guadalquivir River valley (Seville, Spain)

Abstract

A geoarchaeological study of some lithic assemblages found in late Middle Pleistocene and beginning Upper Pleistocene alluvial terraces system has been carried out. The MIS 6/MIS 5 transition in the fluvial terraces of the Guadalquivir River has been identified in the Middle Terraces Complex (MTC) at Tarazona (T11.1, +44–38 m and T11.2, +36–30 m) Seville (Spain). The results were obtained from an archaeological excavation (TAR-III), and two other complementary archaeological sites (TAR-I and TAR-II). Geomorphological cartography, chronostratigraphic study with OSL dating, cantometric analysis and technotypological characterization of 5870 lithic pieces (measurement techniques for erosion and transport on gravels and lithic) have been accomplished. The alluvial chronosequence shows a probable climatic character with autocyclic sedimentary processes correlated with the transition from MIS 6 to MIS 5. Four alluvial Episodes with associated lithic techno-complexes were identified, which refer to the chronostratigraphic transition from Mode 2 to Mode 3 during the late Middle Pleistocene (MIS 6) and the beginning of Upper Pleistocene (MIS 5): Episode 1 with Mode 2 (MIS 6); Episode 2 with varied assemblages that could be associated to Mode 2 or Mode 3 (129/121 ka, MIS 5e and MIS 5d, pre-110 ka); Episode 3 with Mode 3 (between 110 and 104 ka, MIS 5c), and Episode 4 with Mode 3 (post-MIS 5c). The archaeological sites have lithic pieces which were knapped in situ (workshop, habitual or temporary sites) or were slightly displaced. The raw material selection of high quality (quartzites from alluvial deposits) is very notable during Mode 2 (Acheulian) (TAR-I2), Mode 2 or Mode 3 assemblages (TAR-III5) and Mode 3 (TAR-III1, 2, 3). During Mode 3 (Middle Paleolithic) (TAR-II1), the selection of flint raw material was from areas near or in the Guadalquivir terraces.