<p>Orthogonal, oblique and transform rifted margins are defined by the comparison of the structural trend of the margin versus the orientation of the oceanic spreading ridge marked by marine magnetic anomalies. However, when neither transform fault nor marine magnetic anomalies can be identified in the oceanic domain, the determination of the obliquity of extension is delicate and deduced from the architecture of the rifted margins. This setting is illustrated by the Eastern Mediterranean Sea, which is a relic of an oceanic domain, now partly subducted northward underneath Anatolian, Aegean and Calabrian domains. Although the Southern and Eastern margins, from Malta to Lebanon, escaped compressional reactivation during Late Cretaceous and Cenozoic, their potential orthogonal, oblique or transform components have been the subject of extensive debates. Multiple geodynamic scenarios implying different ages and directions of oceanic opening have been proposed suggesting that either the southern or the eastern margins had a transform motion (or highly oblique).</p><p>In this contribution, we investigate the architecture of the different margin segments using 2D and 3D seismic data combined with available stratigraphic records and potential field maps. Based on these observations, we identified and mapped the different rift domains of the Eastern Mediterranean margins, adapting the terminology developed for hyper-extended rifted margins. The Eastern Mediterranean rifted margins are characterized by Mesozoic thick post-rift carbonate platforms developed over moderately thinned continental crust. Distal domains are dominated by thick sedimentary basins (>10 km) where the top basement is barely visible on reflection seismic data. Between the carbonate platform and the distal basin, the transition is always sharp (<30km in width) and marked by large normal faults. The resulting rift domain map highlights different structural trends, which are not coherent with a simple pair orthogonal-transform margins. Moreover, we reconstructed the extensional evolution of the former Northern and Western conjugate margins, which are now integrated in the Alps, Balkanides, Hellenides and Taurides by compiling boreholes and onshore geological data. These fossil margins recorded evidence for different tectonic extensional phases from Permian to Cretaceous. &#160;</p><p>Our preliminary conclusion suggests that poly-phased and poly-directional extension led to distinct breakup ages in the Herodotus and northern Levant Basins. It results in the superposition of extensional structures of different orientations and ages, which inhibit the clear determination of orthogonal, oblique or transform margins. We tentatively explain this architectural complexity by the close position of the East Mediterranean Sea to the migrating rotation pole between Africa and Eurasia during the Mesozoic in relation with the Central Atlantic spreading to the West and the multiple subduction systems of the Neo-Tethys to the North.</p>
<p>At the transition between the Atlantic and the Tethys oceanic systems, the plate kinematic configuration of the East Mediterranean domain during the early Mesozoic is still poorly understood. Several factors like the Messinian salt, the different compressional events, the thick carbonate platforms and Cenozoic deltaic deposits combine to blur the imaging of Eastern Mediterranean rifted margins. This has led to distinct and often markedly contrasting interpretations of the timing of opening (ranging from Carboniferous to Cretaceous), structural evolution (divergent to transform segments) and kinematics (N-S to WNW-ESE extension).</p><p>To address this long-standing problem, we gathered disparate geological observations from the margins surrounding the Eastern Mediterranean Sea to integrate them in a global plate model. Distinct, end-member plate kinematic scenarios were tested, challenged and iterated by observations from the Eastern Mediterranean rifted margins.</p><p>The N-African and NW-Arabian margins of the Eastern Mediterranean Sea are relatively weakly reactivated by the different compressional events and were chosen as the starting point of our integrative tectonic study. Legacy plate models for the area mostly show N-S to NNE-SSW opening of the Eastern Mediterranean of pre-Jurassic age. We have integrated dense industrial seismic data, deep boreholes and dredge data, as well as enhanced satellite gravity images that strongly suggests WNW-ESE oriented lithospheric extension and sea floor spreading during the Late Triassic to Early Jurassic.</p><p>Our approach starts by the mapping of the main extensional and compressional structures, the different crustal domains and the pre-rift facies distribution. We investigate the potential conjugate margins now located and imbricated in the Dinarides, Hellenides and Taurides on the northern side of the East Mediterranean Sea by looking at the drowning ages of the Mesozoic carbonate platform and the related rift structures. We refine the full fit and initial spreading of the Atlantic Ocean using crustal thickness and features observed on both sides of the system to calibrate the motion of Eurasia and Africa, which determine the space available to develop the Eastern Mediterranean Sea. Initial tests on the evolution of the main tectonic plates highlight an insufficient eastward motion of Africa relative to Eurasia (Iberia) to accommodate the extension of Eastern Mediterranean during the Jurassic with a purely WNW-ESE direction of extension. Further hypotheses remain to be tested. However, for now, a scenario involving poly-phased and poly-directional motion of the conjugate continent &#8220;Greater Adria&#8221; during Jurassic is favoured to model the Eastern Mediterranean plate evolution in relation with the closure of the Neo-Tethys further north.</p>
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