Mesozoic-Cenozoic evolution of the intraplate Euphrates fault system, Syria: implications for regional tectonics

Abstract

A lack of dramatic surface geological structures along the Euphrates River in Syria belie a complex tectonic history revealed by newly released seismic reflection and well data. We document the intraplate Euphrates fault system, characterize the variation in structural style along its 350 km length in Syria, and infer its Mesozoic-Cenozoic tectonic and deformational history. We then relate the deformation of the Euphrates system and other proximate intraplate structures to nearby Arabian plate boundary processes in order to develop a new model for the tectonic evolution of the northern Arabian plate.Throughout most of Mesozoic time, the Euphrates area experienced minor deposition compared to the Palmyride trough to its southwest, and the Sinjar trough to its northeast. During latest Cretaceous time, however, significant sinistral transtension occurred along the length of the Euphrates fault system in Syria, with graben formation especially noteworthy in southeastern Syria. This episode was probably related to events at nearby plate boundaries, and may have reactivated a zone of weakness formed during Pan-African accretion of the Arabian plate. A Palaeogene sag basin formed over the graben system in southeastern Syria. Neogene continental collision along the northern and eastern Arabian plate boundaries caused minor reactivation of the Euphrates fault system in a dextral transpressional sense, in concert with significant inversion and the main phase of uplift of the nearby Palmyride and Sinjar mountains.Keywords: Syria, Arabian Plate, intraplate processes, seismic profiles, deformation.The northern Arabian plate comprises diverse structural elements and a variety of temporally and spatially differing structural styles. Although located in a primarily intraplate setting, the tectonic history of Syria has been profoundly affected by events along nearby plate boundaries (Fig. 1). The northern boundary of the Arabian plate represents a collision zone in southern Turkey often referred to as the Bitlis suture (e.g., Sengör & Yilmaz 1981; Hempton 1985). The northwesttrending Zagros collision zone is essentially an eastward continuation of the Bitlis zone, produced by continental collision between Arabia and Iran (e.g., Sengör & Kidd 1979; Berberian & Berberian 1981; Berberian & King 1981; Barazangi 1989). The emplacement of ophiolites during Late Cretaceous time along the northwestern, northern, and eastern margins of the Arabian plate indicates an initial episode of convergence at that time, the extent and nature of which remain controversial (e.g., Beydoun 1991). However, Tertiary island-arc-type volcanism in Iran implies that subduction of oceanic crust continued until Miocene time, when full-fledged continental collision began (e.g., Coleman-Saad 1978). Debate continues concerning the Cenozoic history of the Arabian/Anatolian boundary, with various workers favoring either continued convergence, subduction, and shortening (Yilmaz 1993) or strike-slip motion with periods including both extension and converg...

River terrace development in the NE Mediterranean region (Syria and Turkey): Patterns in relation to crustal type

“…11 shows, this disruption takes the form of short sections of terrace at anomalous heights (lower or higher than expected) and/or strongly tilted. This deformation was attributed by Abou Romieh et al to Quaternary slip on a series of faults, some of which could be matched with faults identified in an earlier seismic survey by Litak et al (1997). Overall there are localized zones of maximum uplift followed by minimum uplift in downstream sequence across the area of deformation, which, from structural evidence, is one of primarily right-lateral deformation, with a minor component of shortening (e.g.…”

“…Overall there are localized zones of maximum uplift followed by minimum uplift in downstream sequence across the area of deformation, which, from structural evidence, is one of primarily right-lateral deformation, with a minor component of shortening (e.g. Litak et al, 1997;Seber et al, 2000). This deformation coincides with the northern end of the Palmyra Fold Belt (Fig.…”

A numerical modelling technique that can account for alternations of uplift and subsidence revealed by Late Cenozoic fluvial sequences

“…Angled arrows correspond to the starts of phases of LCFF identified in uplift modelling by Demir et al (2007). Note that the Euphrates terrace deposits in this part of Syria are affected by active faulting as well as regional uplift (Litak et al, 1997;Abou Romieh et al, 2009); the precise height of any particular terrace thus varies with downstream location (see Abou Romieh et al, 2009, for long-profile projections of the terraces). Nonetheless, this composite transverse profile summarises the nature of this fluvial archive in a manner suitable to highlight the issues raised in the present study.…”

Neogene volcanic activity of western Syria and its relationship with Arabian plate kinematics

“…1). This fault system accommodated the differential motion between the African plate (moving in a N-NE direction relative to the Eurasian Plate at a rate of ∼10 mm/year) and the Arabian micro-plate (moving in a N-NW direction at a rate of ∼18-25 mm/year; McClusky et al, 2003); (b) the formation of the upper Oligocene-Miocene Palmyrides fold-and-thrust belt, made up of deformed Cretaceous-Paleogene formations, aligned along NE-SW directed anticlinals and synclinals in the western Arabian plate, east of the DST (e.g., Al-Saad et al, 1992;Salel and Seguret, 1994;Litak et al, 1997;Rukieh et al, 2005; Fig. 1) and (c) major Cenozoic (mostly Neogene) volcanic activity (e.g., Mouty et al, 1992;Heimann and Ron, 1993;Sharkov et al, 1998;Bertrand et al, 2003;Shaw et al, 2003;Abdel-Rahman and Nassa, 2004;Fig.…”

“…The south-eastern part of Syria (the Rutbah Province of Rukieh et al, 2005) is represented by thick undeformed Phanerozoic sedimentary rocks. Differences in Bouguer gravity values between Aleppo plateau and Rutbah uplift allowed some authors to propose for these regions two different origins as two independent micro-plates amalgamated during late Proterozoic along a suture or a shear zone (now represented by the Palmyrides belt; Best et al, 1990;Litak et al, 1997). According to this view, the Palmyrides belt would have developed in correspondence of an ancient mobile belt, a feature observed also in many other places (e.g., Doglioni, 1995;Vauchez et al, 1997).…”