Succession of pleistocene non-marine sediments containing marine fossils, Mljet island, eastern Adriatic (Croatia)

Small areas of Pleistocene sands occurring on islands in the eastern Adriatic, Croatia, record environmental and depositional conditions during climate changes of that period. The Pleistocene deposits of the Island of Mljet located in the south-eastern Adriatic have been studied using mapping, logging, facies analysis, petrography, heavy minerals and fossil conten. The studied sediments include modified deposits, aeolian deposits and fluvial deposits. Modified sediments originated from previously deposited sands and minor gravels which experienced pedogenic homogenisation. Aeolian deposits are represented by deflationary gravel, dun cross-stratified sands and low-angle laminated sands. Aeolian sands were mostly sourced from exposed, shallow-marine sands. Fluvial deposits include gravels reworked from the slope and colluvial sediments related to the carbonate bedrock, and recycled aeolian sands, which were deposited by high-gradient streams. Two tephra horizons represent former sand-grade volcaniclastic material reworked by streams, mixed with aeolian sand and deposited from river floods shortly after eruption and ash fall. The studied succession includes major stratigraphic surfaces (=super bounding surfaces) related to processes of landscape stabilisation and stratigraphic gaps. The lower, modified part of the succession originated during an interglacial (or interstadial) period. Subsequent aeolian sands reflect the onset of a glacial period characterised by strong, cold winds, and an initial sea-level fall which resulted in the exposure of shallow-marine sands, making them a source for the aeolian sands. It is tentatively proposed that the base of the aeolian deposits corresponds to the onset of the Last Glacial period.