Palaeozoic oceanic crust preserved beneath the eastern Mediterranean

Subduction of oceanic crust into the mantle results in the relatively young Mesozoic-Cenozoic age of the current oceanic basins(1), thus, hindering our knowledge of ancient oceanic lithospheres. Believed to be an exception, the eastern Mediterranean Sea (containing the Herodotus and Levant basins) preserves the southern margin of the Neotethyan, or older, ocean(2-4). An exceptionally thick sedimentary cover(5) and a lack of accurate magnetic anomaly data have led to contradicting views about its crustal nature and age(2-9). Here I analyse total and vector magnetic anomaly data from the Herodotus Basin. I identify a long sequence of lineated magnetic anomalies, which imply that the crust is oceanic. I use the shape, or skewness, of these magnetic anomalies to constrain the timing of crustal formation and find that it formed about 340 million years ago. I suggest that this oceanic crust formed either along the Tethys spreading system, implying the Neotethys Ocean came into being earlier than previously thought, or during the amalgamation of the Pangaea Supercontinent. Finally, the transition from the ratherweak and stretched continental crust found in the Levant Basin(6-8) to the relatively strong oceanic Herodotus crust seems to guide the present-day seismicity pattern as well as the plate kinematic evolution of the region.