Sequence stratigraphy on outcrops in the Gulf of Corinth (Greece): world-class record of multiple regression cycles from the past interglacials

Sequence stratigraphy has predominantly been used on seismic data to interpret basin stratigraphic architectures, especially offshore, but its application to onshore outcrops, and more specifically to the stratigraphic records of the last interglacial periods, remains comparatively rare. The preservation of marine terraces on the southern coast of the Gulf of Corinth (Greece) enables high-resolution study of exposed stratigraphic architectures within terrace deposits.  Fourteen marine terraces corresponding to the last 400 ka are visible in outcrop. This study focuses on the detailed analysis of outcrop sequences in the marine terraces of the Gulf of Corinth, aiming to document multiple regression cycles recorded during past interglacials.

The outcrops are roughly organised in km-large, including hundreds of meters-high Gilbert-type deltas. We identify clinoforms and facies associations thanks to panoramas and stratigraphic logs interpretations and then, we determine the different systems tracts: LST, TST, HST and FSST and the offlap break for the consecutive marine terraces. This enables us to illustrate the processes involved in the formation of marine terraces in relation to eustatic variations. The restored stratigraphic architecture captures an entire record of several cycles organised in an overall forced regression, from the most proximal facies to the most distal ones. This record encompasses the last 400 ka. On this record, we identify almost every HST and some considerable LST and narrow TST in discontinuity with the basement by interpreting topsets, foresets, bottomsets and discontinuities.

We determine how coastline has migrated through time by establishing the trajectory path of the land-sea interface during the last 400 ka. We finally correlate the coastline migration rates with sediment flux dynamics to discuss the relationship between erosion processes and sea-level changes along the coastline.  For example, we illustrate that deposition of sediments in the offshore is more important during low sea levels.

The Gulf of Corinth outcrop sequences could serve as a natural laboratory for testing proxies and understanding the interplay between tectonics, climate, and sea-level changes for the past interglacials.