Geological Society of London
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6. Arkitsa fault, Greece (Jones et al.)

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posted on 2020-01-14, 11:09 authored by K.J.W. McCaffrey, D. Hodgetts, J. Howell, D. Hunt, J. Imber, R.R. Jones, M. Tomasso, J. Thurmond, S. Viseur
This VO dataset shows complex fault geometries developing in an area of active extension, and also illustrates how an enhanced view of the outcrop can be presented by superimposing quantitative geometrical analyses on top of the VO topography. The outcrop is an important analogue for studying the development of 3D fault zones and associated fault damage, and the likely effects on connectivity and reservoir performance. It is located on the eastern shore of Gulf of Evia in central Greece, an area that is currently undergoing active north–south to NE–SW regional extension, with rates on the order of 1–2 mm/year, in response to the complex tectonic interplay between subduction beneath the Hellenic Arc, back-arc extension in the Aegean, and the westward movement of the Anatolian plate. The Arkitsa fault has a throw of >500 m and is part of an array that extends for over 100 km along-strike. The footwall rocks are Upper Triassic–Jurassic platform carbonates and the hanging-wall rocks are Pliocene to Quaternary sediments. The Arkitsa fault is best exposed in an outcrop 450 m south of the main Athens–Lamia national road, where recent quarrying activity during the last 20 years has removed hanging-wall colluvium to reveal clean, fresh exposures of the upper 65–70 m of three large fault panels. This virtual fieldtrip, created using a terrestrial laser scanning (lidar) workflow, shows that it is a powerful and versatile tool that is highly suitable for acquisition of very detailed, precise measurements of slip-surface geometry from well exposed faults (Kokkalas et al. 2007; Jones et al. 2009a). Quantitative analysis of the lidar data, combined with 3D visualization software, allows the spatial variation in various geometrical properties across the fault surface to be clearly shown. Properties such as variation in orientation and curvature (normal, mean and Gaussian) allow culminations and depressions, fault corrugations, and fault splays and bifurcations to be easily identified.