The chronostratigraphy of the latest Middle Pleistocene aeolian and alluvial activity on the Island of Hvar, eastern Adriatic, Croatia

摘要

Pleistocene aeolian sands and alluvial deposits can frequently be traced along the Mediterranean coast. Such deposits also exist along the eastern Adriatic coast and the nearby islands. Four stratigraphical sections of these deposits were studied on the Island of Hvar with the purpose of establishing a chronological framework of the aeolian-alluvial depositional system, using luminescence dating and magnetic susceptibility stratigraphy. Luminescence dating was applied on coarse-grained feldspar and quartz grains separated from the sands. Both quartz optically stimulated luminescence (OSL) and feldspar post-IR infrared stimulated luminescence (pIRIR) age estimates are in good agreement, with values ranging between 167 +/- 24 to 120 +/- 12 ka (OSL) and 179 +/- 18 to 131 +/- 18 ka (pIRIR measured at 290 degrees C) after a fading correction for the pIRIR signal. The results can be clearly correlated to around the end of oxygen isotope stage (OIS) 6 and the beginning of OSI 5, indicating that the aeolian accumulation of sands was a result of the Penultimate Glacial and climate fluctuations at the beginning of the Last Interglacial. Variations in magnetic susceptibility (MS) data can be interpreted alongside these dating results; several stronger peaks detected at the very end of the Penultimate Glacial and the initial stage of the Last Interglacial cycle most probably indicates more intensive pedogenesis resulting from a more favourable climate, probably because of climate changes. Breccias related to major bounding surfaces in association with evidence of soil formation and bioturbation could be the result of more favourable climate conditions and changes during the transition from OIS 6 to OIS 5 (Penultimate Glacial-Last Interglacial). These results are in agreement with similar data from the wider Mediterranean area.