AAPG Geoscience Technology Workshop

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The Offshore Afiq Canyon and its Messinian Yafo Sand apron are Indicators of Young Fluvial Systems Unimpeded by the Levant Rift

Abstract

The offshore extension of Afiq Canyon is a deep valley, buried under thick Plio-Quaternary sediments beneath the continental slope off the southern coastal plain of Israel. The valley is filled with Neogene sediments that are capped by Messinian salt. The age of outcropping strata on the canyon walls indicates the likelihood that the canyon was exposed subaerially during the terminal Messinian stage of Mediterranean desiccation because eroded products of Cretaceous, Paleocene and Eocene age were delivered to an apron of Yafo Sand at the foot of the canyon, interpreted on the basis of its geometry and material from the Or South-1 well as an alluvial/fluvial deposit. Additional valleys of similar dimensions and characteristics to the marine extension of Afiq Canyon occur elsewhere along the continental slope of the entire Levant, suggesting that several rivers of the fluvial system of the Levant, which drained northwestern Arabia to the Mediterranean Sea during the Oligo-Miocene, still prevailed in the Messinian. The Afiq Canyon and its offshore apron as well as equivalents such as the Nahr Menashe fluvial system off Lebanon, imply that the geography of the Levant during late Miocene differed from the present. The Levant rift could not have been a continuous tectonic depression as it is in the present, but rather a sufficiently disconnected series of grabens that allowed large rivers to still flow in between. The presence of the Afiq apron of substantial volume and with a thickness approaching 200 m along its apex confirms active fluvial systems feeding their bedloads into the Mediterranean as recent as 5 million years ago.