Discussion on incipient continental collision and plate-boundary curvature: Late Pliocene–Holocene transtensional Hellenic forearc, Crete, Greece

Abstract

U. Ring & T. C. Brachert write: In their recent paper ten Veen & Kleinspehn (2003) proposed that the western Messara graben of central Crete underwent transtensional deformation since about 3.4 Ma. Transtension is supposed to be dominantly resolved along 070°-striking sinistral faults and that the 070°-striking faults have strike-slip:normal-slip ratios of 10–100:1. Ten Veen & Kleinspehn (2003) then use their results from the western Messara graben to propose that sinistral transtension should represent tectonic escape of central and eastern Crete during incipient collision of the Libyan passive margin. The interpretation of the kinematic data on which ten Veen & Kleinspehn (2003) base their tectonic model is in contrast to earlier studies, which have attributed the young, i.e. Pliocene to Recent, kinematics of Crete largely to radial extension (Angelier et al. 1982; Fassoulas 2001; Ring et al. 2001). Ten Veen & Kleinspehn (2003, p.167) argued that ‘. . . onshore structural assemblages is critical to deciphering forearc kinematics. . .’ and therefore we present our kinematic data from onshore faults in the western and central Messara graben and compare our data together with the fault-slip data of Fassoulas (2001) from the Heraklion graben and microseismicity data (Hatzfeld et al. 1993; Delibasis et al. 1999) with the fault-slip data of ten Veen & Kleinspehn (2003, fig. 9) for discussing the kinematics of the young faults. We believe that fault-slip data directly reflect the kinematics of the faults from which they were collected and therefore allow testing the proposition often Veen & Kleinspehn that sinistral transtension is supposed to be mainly resolved at the 070°-striking faults, the latter of which are known to be an integral part of the youngest set of faults on Crete (Fassoulas 2001) and are in part seismically active (Delibasis et al. 1999). In general, …