Project scientists and colleagues at the Syrian Petroleum Company have studied the regional structure and geologic evolution of Syria. We are currently generating new structural maps and tectonic models for the whole country. Information on this region is relatively limited, despite the local importance of hydrocarbon production and abundant surface and subsurface data. Our regional approach involves new interpretations of seismic reflection profiles, well data, remote sensing imagery, and potential-field data, merged with existing interpretations of similar data sets. These interpretations, integrations, analyses, and map preparation are all performed within a GIS platform.As detailed elsewhere in this issue, the importance of GIS as a data storage and interrogation tool for petroleum exploration is well established. This article describes our use of GIS to facilitate regional tectonic mapping in Syria. Although not directly related to the search for hydrocarbons, the maps and models generated have obvious utility for oil exploration. Herein we detail the types of data being used, their integration and interpretation within the GIS, and our preliminary analysis and findings. We will show how a GIS approach eases data archiving and map generation and also provides interpretational possibilities not available with more traditional mapping procedures.Our interpretations show that much tectonic deformation within Syria occurred within repeatedly reactivated "mobile zones." GIS-generated structural maps on various geologic horizons, and tectonic maps at key time points, illustrate the interconnected and contemporaneous nature of the tectonic episodes within the different Syrian mobile zones. Hydrocarbon plays in Syria, such as the Euphrates Fault System, owe their existence to these tectonic episodes; better understanding of the deformation will lead to more informed exploration strategies. Hence, the data stored within the GIS can directly influence exploration strategies and decisions.Study area and GIS coverages. Our research concerns the northern Arabian Platform, specifically Syria and immediately surrounding areas (Figure 1). Past research by Cornell Syria Project scientists concerns the tectonic evolution of the different tectonic zones within Syria, as delineated in Figure 1. The previous studies established the timing and style of structural deformation within each zone. Previous attempts were made to correlate the findings; however, these past syntheses relied on fewer data than currently available, and a full integration of all available data and results was never attempted. In the current work we are taking a truly regional approach, focusing simultaneously on all parts of the country, notwithstanding nonuniform data distribution.To achieve a fully regional and comprehensive tectonic analysis of Syria, we are constructing data "coverages" or "layers" within a GIS. The geographic extent of each coverage is at least all of Syria. There are three types of
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...
Abstract:We examine the structure and evolution of the Ghab basin that formed on the active, yet poorly understood, northern segment of the Dead Sea transform fault system. The basin formed in PlioQuaternary time at a complex step-over zone on the fault. Subsidence occurred along cross-basin and transform-parallel faults in two asymmetric depocentres. The larger depocentre in the south of the basin is asymmetric towards the east, the margin along which most active transform displacement apparently occurs. The Syrian Coastal Ranges, located directly west of the Ghab basin, are a consequence of Late Cretaceous and Cenozoic regional compression, heavily modified by the Dead Sea fault system and Ghab basin formation. We prefer a model whereby the Dead Sea fault system in northwest Syria developed in Plio-Quaternary time, consistent with previously proposed models of two-phase Dead Sea fault system movement and Red Sea spreading.
Basement depth in the Arabian plate beneath eastern Syria is found t o be much deeper than previously supposed. Deep-seated faulting in the Euphrates fault system is also documented. Data from a detailed 300 k m long reversed refraction profile, with offsets up to 54 km, are analysed and interpreted, yielding a velocity model for the upper 9 km of continental crust. The interpretation integrates the refraction data with seismicreflection profiles, well logs and potential field data, such that the results are consistent with all available information. A model of sedimentary thicknesses and seismic velocities throughout the region is established. Basement depth o n the north side of the Euphrates is interpreted to be around 6 km, whilst south of the Euphrates basement depth is at least 8.5 km. Consequently, the potentially hydrocarbon-rich pre-Mesozoic section is shown, in places, t o be at least 7 km thick. The dramatic difference in basement depth on adjacent sides of the Euphrates graben system may suggest that the Euphrates system is a suture/shear zone, possibly inherited from Late Proterozoic accretion of the Arabian plate. Gravity modelling across the southeast Euphrates system tends to support this hypothesis. Incorporation of previous results allows us to establish the first-order trends in basement depth throughout Syria
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.
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