Stratigraphic architecture, sedimentology and structure of the Middle Pleistocene Corinth Canal (Greece), an analogue for tidal straits

The man-made Corinth canal connects the Aegean Sea with the Corinth Gulf while displaying high steep walls allowing to study the sedimentological structure of this area. A former strait naturally connecting the gulf with the Aegean Sea is assumed in this area. Therefore, this exceptionally well-exposed site could be used as an analogue to study tidal straits after the definition of its stratigraphic architecture, sedimentology and structure. To do so, we used field observations associated with a 3D model built from drone imaging.
We document a first connection at ~1.8 Ma with a facies transition from deep lacustrine to shallow marine environments. Then a second connection as a strait divided in a centre zone and 2 adjacent dune-bedded strait zones. The centre is an active horst where sediment bypass occurred. On both sides opposite dipping conglomeratic dunes are represented by simple and compound dune foreset architectures with multiscale asymmetric herringbones cross stratifications (Figure 1). These observations document a tidal strait with conglomeratic dune bedded strait zones in a micro-tidal context. This interpretation is based on the following criteria (Longhitano & Chiarella, 2020): i) the opposite dipping of the foresets from the central horst, ii) the simple and compound foreset architectures, iii) the lack of mud and the multiscale asymmetric herringbones cross stratifications, that argue for a dune accretion direction and tidal currents to the NW and the SE. The thick set of conglomerates forming tidal dune complexes in the adjacence of the strait-centre zone represents a novelty of this work, as no previous research have documented facies like these.
These ~300 ka strait deposits are the only one preserved in the canal area despite the several highstands recorded by the marine terraces in the Corinth bay. After deposition ended, this connection faded due to regional uplift and offset of Kalamaki-Isthmia fault. This paleostrait improves our understanding of middle to late Pleistocene paleogeography and structural controls on sea connections.