LOESSFEST'09 | Aug. 31st – Sept. 3rd, 2009 |Novi Sad-Serbia
Luminescence Chronology of the Romanian Loess Sequences
Balescu, S.1, Lamothe, M.2
1Laboratoire de Préhistoire et Quaternaire, EA 4221, Université des Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq Cedex, France.
2Laboratoire de Luminescence LUX, Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, CP 8888 Succ. Centre-Ville, H3C 3P8 Montréal, Canada.
The present study focuses on the luminescence chronology of Upper and Middle Pleistocene (< 300 ka) loess deposits of southeastern Romania. The infrared stimulated luminescence (IRSL) dating method is applied to the loess sequences of (1) Tuzla located along the Black Sea shore, (2) Mircea Voda on the Dobrogea plateau and (3) Mostistea in the southeastern Danube plain. These sequences consist of four to seven loess horizons (L1 to L7 downward) alternating with palaeosols (S1 to S7). The two upper palaeosols (S1 and S2) are chernozems developed under steppe vegetation while the lower palaeosols (S3 to S7) are brown-red forest soils formed during more humid climate conditions. The IRSL dating method is applied to silt-sized alkali feldspar grains (40-60μm) from unweathered loess deposits using the multiple aliquot γ dose technique. The measured IRSL ages corrected for long-term fading using the protocol of V. Mejdahl (1988), support the assignment of the three upper loess horizons (L1, L2 and L3) to the last three Pleistocene Glaciations (MIS 2 to 4, MIS 6, MIS 8) and confirm that the Last Interglacial soil (MIS 5e) whose chronostratigraphic position was still debated, corresponds to palaeosol S1. Hence, these IRSL data result in a long chronology contrasting with the previous short chronology proposed by A. Conea (1969) who assigned palaeosols S1 and S2 to Last Glacial interstadials. Moreover, these IRSL results demonstrate that the transition from humid to drier interglacial conditions reflected in the development of the first chernozem soil horizon (i.e. palaeosol S2) within the loessic sequences of southeastern Romania took place during MIS 7.