Reassessing the timeframe of Upper Palaeolithic deposits in the Ceahlau Basin (Eastern Carpathians, Romania): Geochronological and archaeological implications

The Pleistocene deposits capping fluvial terraces in the Bistrita valley (Eastern Carpathians, Romania) host a high density of Upper Palaeolithic (UP) settlements, rendering this area a type-region for Late Pleistocene cultural evolution in eastern Romania and beyond. Despite its archaeological significance, site formation, palaeoenvironmental contextualisation and chronostratigraphy are still insufficiently resolved to draw a consistent picture of UP cultural dynamics. In the frame of recent excavations at the sites Bistricioara-Luarie I and III (BLI, BLIII), we aimed at establishing a comprehensive multi-method (TL on heated flints, OSL on sedimentary quartz, radiocarbon dating of charcoal) chronology of the pluristratified archaeological records contained In the loess-like sediments on the lower and middle terraces of the Bistrita river. Therefore, new chronometric data are reviewed in conjunction with OSL ages and radiocarbon dates of a precursor study (Trandafir et al., 2015). Multi-emission TL ages of four heated flints, OSL sediment ages and radiocarbon dates are consistent within 2 sigma throughout the investigated archaeological profiles and allow a much more precise chronological framing of the identified lithostratigraphic units within the last glacial cycle. However, the silt-sized and sand-sized quartz fractions of a luminescence sample do not always produce identical results at 1 sigma. Numerical ages and field observations indicate that the geological record reaches back to Marine Isotope Stage 5 and is preserved on a lower terrace. Depending on their location, the investigated terrace cover beds represent genetically independent geomorphological units, and up to three palaeosols (cambisols) developed in the cover beds, of which at this stage of research only the youngest (PS1) can be traced unequivocally within all profiles. In archaeological terms, the new chronological framing confirms that the currently identified cultural layers belong to the Late Gravettian (28-25 ka BP), and to several Epigravettian stages (24-15 ka BP), leaving limited chronological space for the previously suspected Aurignacian presence at BLI and at other settlements nearby.