The evolution and stratigraphy of the Corinth Rift
The Gulf of Corinth is a semi-isolated basin that during glacial lowstands was separated from the Mediterranean Sea by the Rion- Antirion sill in the west (e.g., Perissoratis et al. 2000; Mc Neill et al. 2019a). The basin was connected to the Mediterranean Sea during eustatichighstands (corresponding to interglacial intervals), but a wide spectrum of transitional states within the aquatic environment alterations are documented (McNeill et al. 2019b). The evaluation of the timing and form of transition from lacustrine (isolated), to brackish (semi-isolated) or marine conditions can be accurately traced by means of aquatic palynomorph analysis (i.e. freshwater algae, dinoflagellate cysts and foraminifer test lining remains).
The Corinth Rift is a unique laboratory for the study of the early rift development processes due to the fact that it is young (<5Ma), highly active and its complete history has been recorded at high resolution within the onshore and offshore sedimentary deposits (Nixon et al. 2016). The onshore syn-rift sediments, demonstrating a thickness of up to ~2.5km, may be divided into three lithostratigraphic groups: a Lower Group characterized by alluvial to lacustrine sediments deposited in the Late Pliocene; a Middle Group (2.5-1.8Ma to 0.7-0.45Ma ago) dominated by lacustrine fan deltas; and an Upper Group (0.7-0.45Ma ago to present) characterized by alternating marine and lacustrine sediments (e.g. Ori 1989;Gawthorpe et al. 1994; Rohais et al. 2007; Backert et al. 2010; Palyvos et al. 2010; Leeder et al. 2012; Ford et al. 2013).
Up to ~2.5km of sediments have accumulated in the offshore Gulf of Corinth. The syn-rift offshore succession is divided into two seismic stratigraphic units separated by an unconformity (U): the deeper and generally homogenous Seismic Unit 1 (SU1), that is considered to be equivalent to the onshore Middle Group, followed by the well-stratified Seismic Unit 2 (SU2). Integrated sequence stratigraphic interpretations suggest that SU2 represents alternation of marine and lacustrine sediments, recording the glacial-interglacial cycles (Sachpazi et al. 2003; Leeder et al. 2005; McNeill et al. 2005; Lykousis et al. 2007; Bell et al. 2008, 2009; Taylor et al. 2011). SU2 is the equivalent of the onshore Upper Group, while the age of U is considered to be ~0.6Ma (Nixon et al. 2016). Taking into account that onshore sedimentary records are fragmentary and hold taphonomic biases, the Corinth Gulf deposits constitute a unique opportunity for studying both fault and rift evolutionary history and deformation rates, as well as the response of drainage evolution and sediment supply to rift and fault evolution.
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