Middle Pleistocene glaciation, alluvial fan development and sea-level changes in the Bay of Kotor, Montenegro

A coarse-grained alluvial fan at Lipci in the Bay of Kotor, western Montenegro, was deposited in the Middle Pleistocene by a high-energy, steep gradient proglacial stream draining an outlet glacier on the Orjen massif. The fan apex is currently about 50 m above sea-level, but the majority (c. 60%) of this landform now lies offshore. Field mapping, sedimentological analysis and uranium-series dating were combined with a marine bathymetric survey and seismic profiling to explore the morphology and history of the entire fan complex. The Lipci fan was deposited on the margin of a large polje downstream of moraines that formed during the Middle Pleistocene (Marine Isotope Stage 12). The sea-level may have been more than 120 mlower than present during the glacial stages of the Middle Pleistocene. The sediments on the terrestrial portion of the fan are strongly cemented by secondary calcite and the oldest uranium-series ages show that the fan was deposited before 320 ka. These ages are consistent with a larger uranium-series dataset (n = 39) from other glacial and glacio-fluvial formations surrounding Mount Orjen. Seismic profiling of the submerged portion of the fan in the Bay of Kotor shows well-preserved palaeochannels with inset terraces. The Lipci fan is unusual because even its distal segments are well preserved after exposure to multiple post-Marine Isotope Stage 12 regression-transgression cycles. This is probably due to the strong cementation of the fan sediments and its sheltered location in the Bay of Kotor.