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The Sedimentary record of Pleistocene aeolian – alluvial deposits on Vrgada Island (eastern Adriatic coast, Croatia)
; Croatian Geological Survey, Department for Geology, Zagreb, Croatia
Kristina Pikelj ; University of Zagreb, Faculty of Science, Department of Geology, Zagreb, Croatia
Borna Lužar-Oberiter ; University of Zagreb, Faculty of Science, Department of Geology, Zagreb, Croatia
Branko Kordić ; University of Zagreb, Faculty of Science, Department of Geology, Zagreb, Croatia
Vrgada Island is situated in the central part of the eastern Adriatic coast. Upper Cretaceous limestones crop out on the surface and Pleistocene sediments cover them in some parts of the island. This study focused on a coastal cliff trending N – S on the northern part of the island. Aeolian-alluvial deposits, which are 12.5 m thick were analysed and three different facies in this succession described. The lowermost facies A highlights a strong aeolian influence marked by an increased silt percentage and was deposited during colder climate conditions. Sand and gravel in facies B were deposited by streams of dense, cold water formed by melting snow and ice from the nearby Dinaric mountains. The bioturbated sandy facies C was probably formed during a warmer climate. An unusually high percentage of augite in the lowermost part of facies A can be explained by the input of volcanic dust, most likely from the Roman or Campanian volcanoes in Italy. This, combined with the surface textures on quartz grains detected from SEM photographs indicates a short distance transport for the sediment, no matter which mechanism was dominant. The sediments from Vrgada Island represent a transitional zone between the north Adriatic islands, where aeolian sediments dominate and the South - Eastern Adriatic archipelago, where mixed alluvial and aeolian sediments were observed.
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