Transverse and linear dunes in an Upper Pleistocene marine sequence, Corinth Basin, Greece

Abstract

ABSTRACTA range of large‐scale dunes of oolitic calcarenite composition are exposed in the Corinth Basin of central Greece. These transverse dunes and a very large linear dune (> 15 m high) lie within an Upper Pleistocene, transgressive marine sequence. Tidal flow, accelerated by constriction through a narrow, fault‐bounded seaway, is interpreted to have generated the current velocities necessary to produce the dunes.Marine facies in the Upper Pleistocene sequence include beach to offshore conglomerates and sandstones with wave‐modified sedimentary structures and herringbone cross‐stratification. An offshore facies association comprises variably bioturbated siltstones and sandstones with a varied marine fauna that includes thermophile species such as scleractinian corals and Strombus bubonius. Oolitic sandstone facies also occur.Oolitic sands were apparently produced in shoal environments subject to tidal (and wave) action, and transported by dominant southerly currents over the southern part of the basin. Oolites accumulated in a linear dune 2.7 km long and 15–20 m high and in three‐dimensional transverse dunes up to 10 m high having a variety of compound and simple internal geometries. The isolated, WSW‐ENE‐trending linear form exhibits angle of repose sedimentary dips (up to 35°) of avalanche sets on its SE flank and sets typically with dips of 15–20° to the NW. Internal high‐angle discontinuities are developed in the SE‐dipping lee face. It is proposed that a dominant north‐to‐south flow crossed over the crest obliquely, resulting in both net erosional and depositional processes on the lee flank. A subordinate (?tidal) current may have locally and or periodically crossed the dune crest in a westwards direction. A string of transverse dunes, which were located adjacent to a fault/marine terrace scarp, is interpreted to have originally coalesced to form the linear dune.The distribution of transverse and linear dunes together with the palaeogeographical reconstruction suggest that a marine connection periodically existed across the Corinth Isthmus during the Late Pleistocene due to a combination of active faulting and glacio‐eustatic highstands of sea level.