LOESSFEST'09 | Aug. 31st – Sept. 3rd, 2009 |Novi Sad-Serbia
The Loess Record on the Island of Susak, Croatia
Wacha, L.1,2, Mikulčić Pavlaković, S.3, Novothny, Á.1, Crnjaković, M.3, Frechen, M.1
1Leibniz Institute for Applied Geophysics (LIAG), Geochronology and Isotope Hydrology, Stilleweg 2, D-30655 Hannover, Germany
2Croatian Geological Survey, Sachsova 2, 10000 Zagreb, Croatia
2Croatian Natural History Museum, Department of Mineralogy and Petrography, Demetrova 1, 10000 Zagreb, Croatia
Susak, a small island in the North Adriatic Sea, Croatia, is unique because of the great thickness of the Quaternary deposits, which is up to 90 m thick. The deposits on Susak are a remarkable and representative Upper Pleistocene loesspaleosol record of the river Po plain region. They consist of loess, loess derivatives and sand, intercalated with numerous paleosols of different kinds and at least three tephra layers. Thirteen samples were collected for the optically stimulated luminescence (OSL) dating of polymineral fine-grain material. The single aliquot regenerative dose (SAR) protocol, as well as the multiple aliquot additive dose (MAAD) protocol were used for dating. Ages were fading corrected. Independent age control is provided by the radiocarbon dating of charcoal remains. The results show that the two investigated sections (between 8 and 30 m a. s. l.) are a very detailed Oxygen Isotope Stage 3 loess-paleosol record, if correlated with the deep sea record, with short periods of stronger sand deposition. The middle tephra (TF2) shows an age range between 46.0 ± 3.2 ka and 43.4 ± 2.9 ka, based on the luminescence dating results of the loess below and above the tephra layer, and can be related to several central and south Italian volcanic provinces. The possible source area of the uppermost tephra layer (TF3), which is around 32.0 ka old, could be the Campanian Province in South Italy. The great thickness of the deposits is very likely the result of the vicinity of the source area, which is the river Po plain in Northern Italy. During the Pleistocene glacio-eustatic marine regression, the sea level of the Adriatic Sea was well below the present day one and the Po plain extended to the South-east and was exposed to strong wind activity resulting in material transport across the dry North Adriatic basin. The numerous paleosols intercalated in the loess are an evidence of a climate that was milder than the climate which accompanied loess sedimentation in other nearby areas, for example the Carpathian Basin.