Geological and geomorphological evidence of recent coastal uplift along a major Hellenic normal fault system (the Kamena Vourla fault zone, NW Evoikos Gulf, Greece)

摘要

The active normal faulting region of central Greece has been the focus of intense study, due to its relatively high rates of tectonic deformation, and the frequent occurrence of damaging, moderate magnitude earthquakes. The structure of central Greece is dominated by a series of roughly WNW-ESE-trending. extensional faults which have created a series of half-grabens, the most prominent of which are the Gulf of Corinth and the Evoikos Gulf. Of these two structures, the Evoikos Gulf, and particularly its northern part, remains poorly understood in terms of its geodynamic structure and tectonic significance. Here, we use exposed coastal sediment sequences and coastal geomorphological indicators to examine the pattern of historical sea-level change in the northern Evoikos Gulf, specifically in the hangingwall of the prominent Kamena Vourla fault system, to better constrain recent coastal elevational changes and tectonic activity in this area. In particular, we describe and analyse a series of exposed coastal sections which contain recent (<3000 year BP) marginal marine sedimentary units, apparently uplifted to elevations of >1 m above contemporary high water level. These deposits occur in the hangingwall of the prominent Arkitsa (normal) fault strand, and indicate a local uplift rate possibly exceeding 1 mm/year, significantly greater than long-term regional uplift rates. The pattern of uplift of these coastal sections is most consistent with recent coseismic uplift on an offshore, shore-parallel, fault strand north of Arkitsa.