Faulting, seismic‐stratigraphic architecture and Late Quaternary evolution of the Gulf of Alkyonides Basin–East Gulf of Corinth, Central Greece

Abstract

Swath bathymetry, single‐channel seismic profiling, gravity and box coring, 210Pb down‐core radiochemical analyses and sequence stratigraphic analysis in the Gulf of Alkyonides yielded new data on the evolution of the easternmost part of the Gulf of Corinth. Three fault segments, the South Strava, West Alkyonides and East Alkyonides faults, dipping 45, 30 and 45°, respectively, northwards, form the southern tectonic boundary of the Alkyonides Basin. Two 45° southwards dipping segments, the Domvrena and Germeno Faults, form the northern tectonic margin. The Alkyonides Basin architecture is the result of a complex interaction between fault dynamics and the effects of changes in climate and sea/lake level. Chrono‐stratigraphic interpretation of the seismic stratigraphy through correlation of the successive seismic packages with lowstands and highstands of the Late Quaternary indicates that the evolution of the basin started 0.40–0.45 Ma BP and can be divided in two stages. Subsidence of the basin floor during the early stage was uniform across the basin and the mean sedimentation rate was 1.0 m kyear−1. Vertical slip acceleration on the southern tectonic margin since 0.13 Ma BP resulted in the present asymmetric character of the basin. Subsidence concentrated close to the southern margin and sedimentation rate increased to 1.4 m kyear−1 in the newly formed depocentre of the basin. Actual (last 100 year) sedimentation rates were calculated to >2 mm year−1, but are significantly influenced by the presence of episodic gravity flow deposits. Total vertical displacement of 1.1 km is estimated between the subsiding Alkyonides Basin floor and the uplifting Megara Basin since the onset of basin subsidence at a mean rate of 2.4–2.75 m kyear−1, recorded on the East Alkyonides Fault. Gravity coring in the Strava Graben and in the lower northern margin of Alkyonides Basin proved the presence of whitish to olive grey laminated mud below thin marine sediments. Aragonite crystals and absence of the marine coccolithophora Emiliania huxleyi indicate sedimentation in lacustrine environment during the last lowstand glacial interval.

Active faulting at the western tip of the Gulf of Corinth, Greece, from high-resolution seismic data

“…Several studies have been devoted to the mapping of offshore faults in the Gulf of Corinth (Stefatos et al, 2002;Moretti et al, 2003;McNeill et al, 2005a;Lykousis et al, 2007a;Sakellariou et al, 2007aSakellariou et al, , 2007bBell et al, 2008Bell et al, , 2009Taylor et al, 2011;Charalampakis et al, 2014). This study at the western tip of the Gulf results in the completion of the fault map, up to the Rion sill to the west (Fig.…”

“…Concerning the tectonic controls on the rifting, it might result from the extension in the back-arc region of the Aegean subduction zone, enhanced by the interaction with the western tip of the North Anatolian Fault (Armijo et al, , 2004Jolivet, 2001;Hubert-Ferrari et al, 2003;Kokkalas et al, 2006;Reilinger et al, 2010;Pérouse et al, 2012). Except for its Western tip, i.e., west of the town of Aigion, the structure and evolution of the offshore rifting has been reconstructed based on seismic reflection data (Stefatos et al, 2002;Leeder et al, 2002;Moretti et al, 2003;McNeill et al, 2005a;Lykousis et al, 2007a;Sakellariou et al, 2007aSakellariou et al, , 2007bBell et al, 2008Bell et al, , 2009Taylor et al, 2011;Charalampakis et al, 2014). These studies have highlighted a complex basin structure (Bell et al, 2009) characterized by significant along strike variations associated to changes in the inherited basement fabric (Taylor et al, 2011).…”

Strike slip tectonics and transtensional deformation in the Aegean region and the Hellenic arc: Preliminary results

“…6. Interpretation of single channel seismic profiles obtained by HCMR during the last decades ( Figure 2) in the frame of several projects and cruises: HERMES -south and southwest Crete, KM3Net -Southwest Peloponnese, THERA -Santorini area (Sigurdsson et al, 2006;Sakellariou et al, 2010), Gulf of Corinth (Moretti et al, 2004;Lykousis et al, 2007;Sakellariou et al, 2007a), AMPHITRITE -North Evia Gulf (Sakellariou et al, 2007b), North and South Ikarian Basins (Lykousis et al, 1995) and other ( Figure 2). 7.…”

Expedition 381 Scientific Prospectus: Corinth Active Rift Development

“…A dense network of seismic reflection profiles (approximately hundreds of meters to 1-3 km spacing) is available from collaborating groups and published material ( Figure F9; Table T2), including deep penetrating lines imaging basement (Sachpazi et al, 2003(Sachpazi et al, , 2007Clément et al, 2004;Zelt et al, 2004Zelt et al, , 2005Taylor et al, 2011) and high-resolution single and multichannel data revealing a detailed sequence stratigraphy of the synrift sequences (Stefatos et al, 2002;Leeder et al, 2005;McNeill et al, 2005;Lykousis et al, 2007;Sakellariou et al, 2007;Bell et al, 2008Bell et al, , 2009. The ability to integrate these data sets and to correlate key horizons and sequences has been demonstrated in recent publications (e.g., Bell et al, 2008Bell et al, , 2009Taylor et al, 2011).…”

“…Seismic profile spacing and hence horizontal resolution is hundreds of meters to ~2 km for the majority of the active rift. Example publications showing different seismic data sets: Ewing, 2001 (Zelt et al, 2004;Taylor et al, 2011);Vasilios multichannel, 2003Bell et al, 2008Bell et al, , 2009); Aegeao Sakellariou et al, 2007); Vasilios single channel, 1996 (Leeder et al, , 2005; Shackleton, 1982 (Stefatos et al, 2002;Higgs, 1988); high-resolution pinger/sparker (Stefatos et al, 2002;Charalampakis et al, 2014). Locations of existing piston and gravity cores are also shown (red dot = HCMR cores partly unpublished; red star = Moretti et al [2004], blue dot = Collier et al [2000]).…”