A new insight into the structural evolution of Rosetta Fault, eastern margin of Herodotus Basin, East Mediterranean

Abstract

While exploration activities are flourishing in both the offshore Nile Delta Basin and the Levant Basin, Herodotus Basin remains unexplored. The study of the complex tectonic evolution of this basin is mainly hindered by large water depths, insufficient and poor seismic imaging, as well as the scarcity of well penetrations. The present study offers a new insight into the tectonic history of the eastern margin of Herodotus Basin through detailed structural study of the Rosetta Fault. Detailed structural mapping of Rosetta Fault using 3D seismic and borehole data reveals its complicated deformation history. Together with other NE-SW oriented faults in the Levant Basin and the northern Egypt onshore area, Rosetta Fault experienced different phases of slip at different times including normal slip due to extensional deformation at Triassic to early Cretaceous times and reverse slip at Late Cretaceous to Tortonian times due to the convergence of Eurasia and Afro-Arabia. Contrary to the findings of some plate tectonic models, which consider NE-SW drift of Afro-Arabia and Eurasia, the present study suggests that the direction of Mesozoic extension in Herodotus Basin (as well as the Levant Basin and the northern onshore areas of Egypt) was NW-SE based on the orientations of Mesozoic active faults. Rosetta Fault also shows deformation by sinistral transtension at Messinian and Holocene times intervened by Plio-Pleistocene normal slip. When the Rosetta Fault was affected by normal slip and transtensional deformation at Messinian to Holocene times, the Herodotus Basin lying to the NW of it was affected by NW-SE shortening associated with the Hellenic subduction. The obvious contrast in the deformation style of Rosetta Fault and the Herodotus Basin is attributed to the irregular shape of the convergent plate boundary extending from south Cyprus to SE Crete.