Offshore basin evolution and normal fault migration in the western North Gulf of Evia rift

James Wood , Rebecca E. Bell, Alexander C Whittaker, Saoirse Coveney, Frank Chanier, Fabien Caroir, Haralambos Kranis , Athanassios Ganas

Active extension in the North Gulf of Evia, Central Greece is contemporaneous with the well-studied Gulf of Corinth but displays a contrasting style of complex rifting with marked rotational and strike-slip influence from the North Anatolian Fault. We develop a late-Quaternary, syn-kinematic sedimentary age model for the Western Basin of the North Gulf of Evia using 2D seismic reflection data. Seismic stratigraphic principles are used to identify three key horizons based on reflection termination relationships with ages of ~12 ka, ~130 ka and ~325 ka assigned using a sequence stratigraphic model on deltaic clinoform packages. The age model is applied across the basin alongside a network of offshore faults to determine the major structural components, depocenters and evolutionary history of the rift system. We resolve the major controlling faults in the basin to be the Kalypso Fault (~4 mm/yr slip) on the southern margin and the Central Graben (~1-2 mm/yr slip) along the axis of the gulf. We show that the Kalypso Fault is linked to the onshore Coastal Fault System, one of the most active normal fault zones of the rift. The timing of initiation of the Kalypso Fault is constrained to ~325 ka based on thickening relationships of syn-kinematic sediments following a strain localisation (i.e. migration) event with evolving strike from the onshore, Arkitsa Fault. The age model and fault network outlined here aim to further unlock detailed work in the gulf to answer key questions on normal fault behaviour, rift evolution, and associated geohazards in complex settings.