Distributed normal faulting in the tip zone of the South Alkyonides Fault System, Gulf of Corinth, constrained using 36Cl exposure dating of Late-Quaternary wave-cut platforms.

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Authors

Jenni Robertson , Gerald Roberts, Francesco Iezzi, Marco Meschis , Delia Gheorghiu, Diana Sahy, Chris Bristow, Claudia Sgambato

Abstract

In order to investigate the geometry, rates and kinematics of active faulting in the region close to the tip of a major crustal-scale normal fault in the Gulf of Corinth, Greece, we have mapped faults and dated their offsets using a combination of 234U/230Th coral dates and in situ 36Cl cosmogenic exposure ages for sediments and wave-cut platforms deformed by the faults. Our results show that deformation in the tip zone is distributed across as many as eight faults arranged within ~700 m across strike, each of which deforms deposits and landforms associated with the 125 ka marine terrace of Marine Isotope Stage 5e. Summed throw-rates across strike achieve values as high as 0.3-1.6 mm/yr, values that are relatively high compared to that at the centre of the crustal-scale fault (2-3 mm/yr from Holocene palaeoseismology and 3-4 mm/yr from GPS geodesy). The relatively high deformation rate and distributed deformation rate in the tip zone are discussed in terms of stress enhancement from rupture of neighbouring crustal-scale faults and in terms of how this should be considered during fault-based seismic hazard assessment.

DOI

https://doi.org/10.31223/osf.io/r4jpa

Subjects

Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

normal faulting, 36Cl exposure dating, Deformed marine terraces, Distributed faulting, Fault tip zone, Wave-cut platform

Dates

Published: 2019-10-24 09:01

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License

GNU Lesser General Public License (LGPL) 2.1

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