Tectono‐sedimentary processes along an active marine/lacustrine half‐graben margin: Alkyonides Gulf, E. Gulf of Corinth, Greece

Abstract

The Alkyonides half-graben is separated from the Gerania Range to the south by active faults whose offshore traces are mapped in detail. The East Alkyonides and Psatha Faults have well-defined, Holocene-active tip zones and cannot be extrapolated from the onshore Skinos Fault into a single continuous surface trace. During the late Quaternary, catchments draining the step-faulted range front have supplied sediment to alluvial fans along a subsiding marine ramp margin in the hangingwall of the Skinos Fault, to shelf ledge fans on the uplifting footwall to the East Alkyonides Fault and to the Alepochori submarine fan in the hangingwall of the latter. During late Pleistocene lowstand times (c. 70-12 ka), sediment was deposited in Lake Corinth as fan deltas on the subsiding Skinos shelf ramp which acted as a sediment trap for the adjacent 360 m deep submarine basin plain. At the same time, the uplifting eastern shelf ledge was exposed, eroded and bypassed in favour of deposition on the Alepochori submarine fan. During Holocene times, the Skinos bajada was first the site of stability and soil formation, and then of substantial deposition before modern marine erosion cut a prominent cliffline. The uplifting eastern shelf ledge has developed substantial Holocene fan lobe depositional sequences as sediment-laden underflows have traversed it via outlet channels. We estimate mean Holocene displacement rates towards the tip of the Psatha Fault in the range 0.7-0.8 mm year-1. Raised Holocene coastal notches indicate that this may be further partitioned into about 0.2 mm year-1 of footwall uplift and hence 0.5-0.6 mm year -1 of hangingwall subsidence. Holocene displacement rates towards the tip of the active East Alkyonides Fault are in the range 0.2-0.3 mm year-1. Any uplift of the West Alkyonides Fault footwall is not keeping pace with subsidence of the Skinos Fault hangingwall, as revealed by lowstand shelf fan deltas which show internal clinoforms indicative of aggradational deposition in response to relative base-level rise due to active hangingwall subsidence along the Skinos Fault. Total subsidence here during the last 58 kyr lowstand interval of Lake Corinth was some 20 m, indicating a reduced net displacement rate compared to estimates of late Holocene

Statistical mechanics and scaling of fault populations with increasing strain in the Corinth Rift

“…b) Geodetic "horizontal extension rates" across the Rift according to Clarke et al (1998). c) Late Quaternary uplift rates according to 1) Houghton et al (2003), 2) De Martini et al (2004), 3) Leeder et al (2003), 4) Armijo et al (1996), 5) Roberts et al (2009), 6) and 7) Collier et al (1992). d) Summation of upper-crust extension (black) and whole-crust extension derived from crustal thinning (dark red) and basement subsidence (light grey) along three transects in the Corinth Rift (Bell et al, 2011).…”

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

“…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).…”

A comparison of the Iberian and Ebro Basins during the Permian and Triassic, eastern Spain: A quantitative subsidence modelling approach

“…From this perspective we are able to unravel more about the tectonic processes driving Permian and Mesozoic basin formation in the Ebro and Iberian basins. In particular, we aim to discuss the predictions of forward modelling in the framework of observations on fault morphology and a number of other tectonic processes controlling the evolution of particular sectors of each basin (Leeder and Gawthorpe, 1987;Gibbs, 1990;Kooi et al, 1992;van Wees and Cloetingh, 1994;Gawthorpe and Leeder, 2000;Leeder et al, 2002;Young et al, 2002).…”