Mineralogical and geochemical characteristics of Quaternary sediments from the Island of Susak (Northern Adriatic, Croatia)

Middle and Upper Pleistocene loess-palaeosol sequences up to 90 m thick are exposed on the Island of Susak located in the Northern Adriatic Sea in Croatia. During glacial times the sea level was up to about 120 m lower and a significant part of the Adriatic became land. The source area of the primary aeolian sediments was in the vicinity of the island and is related to the southward extended River Po plain. The loess has a mainly clayey to sandy silt or sand grain-size and is intercalated by at least three tephras, numerous palaeosols and calcareous segregations. The heavy mineral association points to metamorphic and igneous rocks from Alpine regions as source material of the loess. Geochemical and mineralogical properties of loess and palaeosols differentiate one from another and reflect the intensity of weathering and pedogenesis. The oldest tephra contains vitroclasts and serrated clinopyroxene while the middle and the youngest tephra along with vitroclasts, contain idiomorphic augite as diagnostic volcanic features. Based on bulk rock and vitroclast chemistry, morphology of pyroxenes, and the age of the loess sandwiching the tephra, the potential source of this volcanic material could very likely be the Campanian or Aeolian volcanic province in southern Italy. Infrared stimulated luminescence dating-results show that the major part of the aeolian deposits including the tephra layers correlates to MIS 3-MIS 5.