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

Abstract

A 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.

High-resolution provenance determination of construction-stone: A preliminary study of Corinthian oolitic limestone quarries at Examilia

“…Regional variation originates from the differing compositions of the clastic input into the ooid shoal areas from the various areas of high ground bordering the shallow marine shelf (Collier and Thompson, 1991;Hayward and Williams, in prep.). In the northeast of the EQL, this input was relatively copious and comprised the fine-to coarse-grained weathering products of altered mafic and ultramafic rocks.…”

“…) during the Tyrrhenian (200 ka) (Collier and Thompson, 1991). The dunes and underlying Pliocene and Pleistocene marls, limestones, sandstones, and conglomerates have been uplifted during the last few hundred ka during the regional uplift which affects the whole northern Peloponnese (Keraudren and Sorel, 1987).…”

“…The detailed sedimentology of the Examilia dune has been described in Collier and Thompson (1991). In general, the limestone of the EQL is a thinly bedded and thinly laminated, fine-grained oosparite and oointrasparite (average grain-size range is 150-350 pm).…”

A reconstruction of the pre‐8th century B.C. palaeotopography of central Corinth, Greece

“…This calcrete is in places exposed at the modern surface within the excavated archaeological site and the surrounding area, and in eroded exposures can be difficult to distinguish from the later, Holocene nodular calcrete developed over the oolite. The oolite, the last marine sediment to form on the terrace, formed as a series of large submarine dunes through the banking up of ooid sands by current action (Collier and Thompson, 1991). Individual dunes coalesced over time to form a line that trends approximately WSW -ENE across the study area (Figure 1a).…”

“…For further details on the geology of the region, see von Freyberg (1973), Vita-Finzi and King (1985), Keraudren and Sorel (1987), Collier (1990), and Collier and Thompson (1991). In the descriptions below, the term "quarry" is used to denote a discrete, localized area within which there is visible evidence for stone extraction (quarry faces, tool marks, etc.).…”