Origin of the Eastern Mediterranean: Neotethys rifting along a cryptic Cadomian suture with Afro-Arabia

Abstract

The Eastern Mediterranean is a land-locked basin, a remnant of the Neotethys Ocean. It was formed in the Permian−Triassic as a result of the drift of the Tauride block from the Afro-Arabian margin of Gondwana. Herein, we show that rather than being a genuine Afro-Arabia crustal fragment, the Tauride block is underlain by late Neoproterozoic Cadomian basement, which differs significantly from the Neoproterozoic “Pan-African” basement of NE Africa from which it was detached. Resembling other Cadomian terranes of western Europe, the Tauride basement is chiefly a graywacke succession deposited in a mid- to late Ediacaran back-arc basin formed on the periphery of Afro-Arabia, above the southward-subducting proto-Tethys Ocean. The back-arc region was deformed and metamorphosed to various degrees and intruded by latest Ediacaran−Cambrian granites and volcanics during the Cadomian orogeny. Unlike the protracted (∼300 m.y.) Neoproterozoic crustal evolution recorded in Afro-Arabia, the Cadomian basement of the Taurides evolved briefly, over ∼50 m.y. We show that the entire cycle of sedimentation, metamorphism, and magmatism in the Tauride basement took place in the late Ediacaran−Cambrian and lagged after Neoproterozoic Pan-African orogeny and igneous activity in Afro-Arabia. The Cadomian orogeny accreted the Taurides, and adjoining peri-Gondwana Cadomian terranes, with an already-consolidated Afro-Arabian continent. Permian−Triassic rifting of the Eastern Mediterranean occurred close to the transition between these two domains. Rifting was thus inherited from, and superimposed on, late Ediacaran structures formed in front of the current Afro-Arabia margin of Gondwana during Cadomian orogeny. The boundary between the Cadomian edifice and the Pan-African crust of Afro-Arabia appears to lie presently on the southern margin of the Mediterranean, extending from Morocco in the west to Arabia in the east. Hence, the continental margin of the Eastern Mediterranean, including in the Levant Basin, is probably underlain by a thinned Cadomian crust.