The Late Miocene Rifian corridor as a natural laboratory to explore a case of ichnofacies distribution in ancient gateways

Abstract Oceanic gateways have modulated ocean circulation and influenced climatic variations throughout the Earth´s history. During late Miocene (7.8–7.35 Ma), Atlantic Ocean Mediterranean Sea were connected through Rifian Corridor (Morocco). This gateway is one of few examples deep ancient seaways with a semi-continuous sedimentary record. Deposits comprise turbidites intercalated between deep-sea mudstone (i.e., hemipelagites drift deposits), channelized sandstone contourite facies, shallow marine sandstone. Herein an ichnological analysis was conducted in these upper sediments to improve characterisation palaeoenvironmental conditions. In addition, ichnofacies analysed elucidate how bottom currents control distribution can modify their attributes. Turbidite deposits are typified by vertical trace fossils Ophiomorpha ), conforming rudis ichnosubfacies. Contouritic exhibits high density low diversity trace-fossil assemblage, predominant Macaronichnus Scolicia , resembling proximal expression Cruziana ichnofacies. Shallow environments dominated (e.g., Conichnus Ophiomorpha, Skolithos allowing assignation study reveals for first time variability attributes at Corridor, associated turbidites, sediments. Hydrodynamic energy as major factor controlling maker communities studied seaway. Highly energetic conditions typical shallower settings present deeper-water slope), contributing ichnodiversity impoverishment