Evolution of the offshore western Gulf of Corinth

Abstract

The young Gulf of Corinth rift in centralGreece is an ideal place to study processes occurring during the initiation and early stages of continental extension. At the east end of the 100-km-long E-W rift, Holocene extension on N-dipping faults equates to geodetic extension rates. At the western end, however, estimated extension rates on N-dipping onshore faults account for only ~20%-40% of the geodetically measured rates (~10-15 mm/ yr). We use high-quality, multichannel, seismic refl ection and swath bathymetry data to investigate the tectonics of the western Gulf and quantify the contribution of offshore fault activity toward total-rift extension. Five major offshore faults generate the variable basement topography, and a ca. 0.4-Ma unconformity separates stratigraphy into two main packages. Basin-fi ll geometry indicates that during the early stages of subsidence of the offshore western Gulf, S-dipping faults were the dominant border-fault structure. This is still the case at the western end of the western Gulf; however, elsewhere, Ndipping faults on the south margin are now relatively more dominant and cause stratigraphy to tilt south. The temporally and spatially varying rift structure contrasts with the simple, consistently N-dipping, borderfault, half-graben geometry of the east Gulf of Corinth. Combined west Gulf offshore and onshore Holocene fault extension rates total 5-14.5 mm/yr, within the range calculated geodetically, and render enhanced slip on a low-angle detachment surface beneath the western Gulf unnecessary.

Patterns of Quaternary uplift of the Corinth rift southern border (N Peloponnese, Greece) revealed by fluvial landscape morphometry

“…On the northern side of the basin, Bell et al (2008) observe partial northward transfer of fault activity from the West and East Channel faults to the South and North Eratini faults (Fig. 1) since 0.5 Ma.…”

“…However, Nixon et al (2013) consensually displace the main transition from ~0.68 to 0.60 Ma because the late-rift section is made of six marine-lacustrine packages that they associate to the last six glacial cycles. This 0.6 Ma discontinuity corresponds also to the main boundary within the seismic profiles that Bell et al (2008Bell et al ( , 2009) put around 0.4 Ma. Keeping in mind the dating uncertainties, the isopach maps of Taylor et al (2011) describing sedimentation in the gulf show that, before 0.7 Ma, two separate depocentres existed, a main one situated in the west-central gulf in front of the southern coast between Akrata and Derveni, and a minor one in the eastern gulf.…”

“…Many seismic reflection studies contributed in the last decade toward an improved mapping of active offshore faults (e.g., Stefatos et al, 2002;Lykousis et al, 2007;Bell et al, 2008;Taylor et al, 2011;Beckers et al, 2015). The mostly north-dipping faults of the southern margin are grouped in several parallel lines of right-stepping en-échelon faults, both on-and offshore.…”

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

“…Our seismic lines tie with Bell et al's (2009) data set, therefore a direct correlation with our data set is possible and allows to estimate the age of our Ford et al (2009Ford et al ( , 2013, Palyvos et al (2005Palyvos et al ( , 2008, Flotté et al (2005), and references therein. Main offshore faults from Flotté et al (2005) for the Gulf of Patras, this study, McNeill et al (2005a), Bell et al (2008), and Taylor et al (2011 for the Western and Central Gulf of Corinth. Isobaths from Bell (2008).…”

“…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).…”