AAPG Geoscience Technology Workshop

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Structural Evolution of the Eastern Mediterranean, Levant Basin During Mesozoic Tethyan Rifting: A Conceptual Rifting Model Based Upon 2-D Kinematic Restorations

Abstract

Structural restorations of cross-sections spanning the Levant Basin describe both an evolution of Mesozoic, Tethyan rifting and a spatial and temporal distribution of Mesozoic petroleum systems elements. The structural models are based upon 2-D depth reflection seismic, refraction seismic, and data from bore-hole penetrations. Although both the timing of break-up and crustal composition are under-constrained it is generally agreed that the crust underlying the central Levant Basin is less than 10 km thick (e.g., Makris et al, 1983; Netzeband, 2006). Furthermore, based upon additional geophysical analyses (3-D gravity-inversion coupled with flexural back-stripping) the crust in the Levant Basin can be interpreted as highly attenuated (thinning factors up to 0.9) Pan-African, continental-crust with possible magmatic addition (Cowie 2012; Steinberg et al, 2018). 2-D structural restorations presented here describe the kinematics of crustal stretching and thinning in the Levant Basin that presumably resulted in break-up and seafloor spreading in the Herodotus Basin, west of the present-day position of the Eratosthenes Seamount. A paradigm shift in the understanding of passive margin evolution has led to the recognition that low-angle detachments can play a significant role in the attenuation of continental crust and mantle exhumation leading to complete break-up of the lithosphere (e.g., Manataschal, 2004). Accordingly, we propose a spatially migrating, poly-phase rift model, that includes the possibility of hyper-extension of the continental crust on low-angle, crustal-scale detachments. In this model, many of the resulting intra-basin structures with crustal-roots are expected to be variably rotated and eroded continental fragments. The Eratosthenes Seamount is characterized as either a continental ribbon (in the broad sense of Lister et al, 1986; Peron-Pinvidic and Manatschal, 2010) or a stranded continental hanging block (in the broad sense of Lavier and Manatschal, 2006; Mohn et al, 2010) with magmatics added before, during, or after the Tethyan rifting event. The proposed conceptual model of rift evolution could have significant implications to a potential Mesozoic petroleum system in the Levant Basin. For example, diachronous sedimentation associated with outward migration of both tectonic strain and rift-related mantle upwelling could result in a non-uniform distribution of potential source and reservoir rocks. Despite extreme thinning of the crust, the mantle upwelling (and possible magmatic additions) could mitigate subsidence such that crustal-fragments are kept elevated to relatively shallow water conditions suitable for carbonate growth late into the syn-rift and onset of break-up. Key challenges to developing the conceptual model include post-rift tectonism (principally contractional overprinting) associated with closure of the Tethyan ocean realm leading to inter-continental collision and several magmatic episodes spanning the Mesozoic and Cenozoic.