Tectonic and geologic evolution of Syria

Publisher's version archived with permission from publisher.Using extensive surface and subsurface data, we have synthesized the Phanerozoic tectonic and geologic evolution of Syria that has important implications for eastern Mediterranean tectonic studies and the strategies for hydrocarbon exploration. Syrian tectonic deformation is focused in four major zones that have been repeatedly reactivated throughout the Phanerozoic in response to movement on nearby plate boundaries. They are the Palmyride Mountains, the Euphrates Fault System, the Abd el Aziz-Sinjar uplifts, and the Dead Sea Fault System. The Palmyrides include the SW Palmyride fold and thrust belt and two inverted sub-basins that are now the Bilas and Bishri blocks. The Euphrates Fault System and Abd el Aziz-Sinjar grabens in eastern Syria are large extensional features with a more recent history of Neogene compression and partial inversion. The Dead Sea transform plate boundary cuts through western Syria and has associated pull-apart basins. The geological history of Syria has been reconstructed by combining the interpreted geologic history of these zones with tectonic and lithostratigraphic analyses from the remainder of the country. Specific deformation episodes were penecontemporaneous with regional-scale plate-tectonic events. Following a relatively quiescent early Paleozoic shelf environment, the NE-trending Palmyride/Sinjar Trough formed across central Syria in response to regional compression followed by Permian-Triassic opening of the Neo-Tethys Ocean and the eastern Mediterranean. This continued with carbonate deposition in the Mesozoic. Late Cretaceous tectonism was dominated by extension in the Euphrates Fault System and Abd el Aziz-Sinjar Graben in eastern Syria associated with the closing of the Neo-Tethys. Repeated collisions along the northern Arabian margin from the Late Cretaceous to the Late Miocene caused platform-wide compression. This led to the structural inversion and horizontal shortening of the Palmyride Trough and Abd el Aziz-Sinjar Graben

Design and development of information systems for the geosciences: An application to the Middle East

Publisher's version archived with permission from publisher. http://www.gulfpetrolink.net/publication/geoarabia.htmAs our understanding grows of how the Earth functions as a complex system of myriad interrelated mechanisms, it becomes clear that a revolutionary and novel approach is needed to study and understand it. In order to take advantage of an ever-growing number of observations and large data sets and to employ them efficiently in multidisciplinary studies aimed at solving earth system science problems, we are developing a comprehensive Solid Earth Information System (SEIS). The complex nature of the solid earth sciences raises serious challenges for geoscientists in their quest to understand the nature and the dynamic mechanisms at work in the planet. SEIS forms a first step in developing a broader and more comprehensive information system for earth system sciences designed for the needs of the geoscientists of the 21st century. In a way, SEIS is a step towards the Digital Earth. Application of SEIS to the complex tectonics of the Middle East shows that information systems are crucial in multidisciplinary research studies and open new avenues in research efforts. SEIS includes an Internet module that provides open access to anyone interested. Researchers as well as educators and students can access this knowledge and information system at http://atlas.geo.cornell.edu

Global Positioning System measurements of strain accumulation and slip transfer through the restraining bend along the Dead Sea fault system in Lebanon

Approximately 4 yr of campaign and continuous Global Positioning System (GPS) measurements across the Dead Sea fault system (DSFS) in Lebanon provide direct measurements of interseismic strain accumulation along a 200-km-long restraining bend in this continental transform fault. Late Cenozoic transpression within this restraining bend has maintained more than 3000 m of topography in the Mount Lebanon and Anti-Lebanon ranges. The GPS velocity field indicates 4-5 mm yr-1 of relative plate motion is transferred through the restraining bend to the northern continuation of the DSFS in northwestern Syria. Near-field GPS velocities are generally parallel to the major, left-lateral strike-slip faults, suggesting that much of the expected convergence across the restraining bend is likely accommodated by different structures beyond the aperture of the GPS network (e.g. offshore Lebanon and, possibly, the Palmyride fold belt in SW Syria). Hence, these geodetic results suggest a partitioning of crustal deformation involving strike-slip displacements in the interior of the restraining bend, and crustal shortening in the outer part of the restraining bend. Within the uncertainties, the GPS-based rates of fault slip compare well with Holocene-averaged estimates of slip along the two principal strike-slip faults: the Yammouneh and Serghaya faults. Of these two faults, more slip occurs on the Yammouneh fault, which constitutes the primary plate boundary structure between the Arabia and Sinai plates. Hence, the Yammouneh fault is the structural linkage that transfers slip to the northern part of the transform in northwestern Syria. From the perspective of the regional earthquake hazard, the Yammouneh fault is presently locked and accumulating interseismic strain

Crustal deformation in northwestern Arabia from GPS measurements in Syria: Slow slip rate along the northern Dead Sea Fault

New Global Positioning System (GPS) measurements in NW Syria provide the first direct observations of near-field deformation associated with the northern Dead Sea fault system (DSFS) and demonstrate that the kinematics of the northern section of this transform plate boundary between the Arabian and Sinai plates deviate significantly from plate model predictions. Velocity estimates based on GPS survey campaigns in 2000, 2007 and 2008, demonstrate left-lateral shear along the northern DSFS with 1σ uncertainties less than 0.7 mm yr-1. These velocities are consistent with an elastic dislocation model with a slip rate of 1.8-3.3 mm yr-1 and a locking depth of 5-16 km. This geodetically determined slip rate is about half of that reported farther south along the central section (Lebanese restraining bend) and the southern section (Jordan Valley and Wadi Araba) of the transform and consequently requires some deformation to occur away from the transform along other geological structures. The factor of two difference in slip rates along the transform is also consistent with differing estimates of total fault slip that have occurred since the mid Miocene: 20-25 km along the northern DSFS (in NW Syria) versus about 45 km along the southern DSFS segment. Some of the strain deficit may be accommodated by north-south shortening within the southwestern segment of the Palmyride fold belt of central Syria. Additionally, a distinct change in velocity occurs within the Sinai plate itself. These new GPS measurements, when viewed alongside the palaeoseismic record and the modest level of present-day seismicity, suggest that the reported estimates of recurrence time of large earthquakes (M > 7) along the northern section of the DSFS may be underestimated owing to temporal clustering of such large historical earthquakes. Hence, a revised estimate of the earthquake hazard may be needed for NW Syria

Active tectonics of the western Mediterranean: Geodetic evidence for roll back of a delaminated subcontinental lithospheric slab beneath the Rif Mountains, Morocco

Copyright 2006, Geological Society of America. See also: http://www.geosociety.org; http://atlas.geo.cornell.edu/morocco/publications/fadil2006.htmSurface deformation in Morocco derived from five years of GPS survey observations of a 22-station network, four continuously recording GPS stations, and four IGS stations in Iberia indicate roughly southward motion (~3 mm/yr) of the Rif Mountains, Morocco relative to stable Africa. Motion of the Rif is approximately normal to the direction of Africa-Eurasia relative motion, which is predominantly strike slip, and results in shortening of the Rif and subsequent crustal extension of the adjacent Alboran Sea region. The sense, and the N-S asymmetry of the observed deformation (i.e., no evidence for north-directed shortening in the Betic Mountains north of the Alboran Sea) cannot be easily explained in terms of crustal plate interactions suggesting that dynamic processes below the crust are driving the recent geologic evolution of the western Mediterranean. The model that best fits the observations involves delamination and southward roll back of the African lithospheric mantle under the Alboran and Rif domains