The Late Miocene Rifian corridor as a natural laboratory to explore a case of ichnofacies distribution in ancient gateways
Metadatos
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Nature Research
Date
2021-02-18Referencia bibliográfica
Miguez-Salas, O., Rodríguez-Tovar, F. J., & de Weger, W. (2021). The Late Miocene Rifian corridor as a natural laboratory to explore a case of ichnofacies distribution in ancient gateways. Scientific Reports, 11(1), 1-10. [https://doi.org/10.1038/s41598-021-83820-x]
Patrocinador
Secretaria de Estado de I+D+I, Spain CGL2015-66835-P PID2019-104625RB-100; FEDER Andalucía B-RNM-072-UGR18; Junta de Andalucía P18-RT-4074; Scientific Excellence Unit (Universidad de Granada) UCE-2016-05; Ministerio de Educación, Cultura y Deporte (Gobierno de España); BP; ENI; Exxon Mobile; SpectrumRésumé
Oceanic gateways have modulated ocean circulation and have influenced climatic variations
throughout the Earth´s history. During the late Miocene (7.8–7.35 Ma), the Atlantic Ocean and
the Mediterranean Sea were connected through the Rifian Corridor (Morocco). This gateway is
one of the few examples of deep ancient seaways with a semi-continuous sedimentary record.
Deposits comprise turbidites intercalated between deep-sea mudstone (i.e., hemipelagites and
drift deposits), channelized sandstone contourite facies, and shallow marine sandstone. Herein an
ichnological analysis was conducted in these upper Miocene sediments to improve characterisation
of palaeoenvironmental conditions. In addition, ichnofacies were analysed to elucidate how
bottom currents control ichnofacies distribution and can modify their attributes. Turbidite deposits
are typified by vertical trace fossils (i.e., Ophiomorpha), conforming the Ophiomorpha rudis
ichnosubfacies. Contouritic sandstone exhibits high density and low diversity trace-fossil assemblage,
with predominant Macaronichnus and Scolicia, resembling a proximal expression of the Cruziana
ichnofacies. Shallow marine environments are dominated by vertical trace fossils (e.g., Conichnus,
Ophiomorpha, Skolithos), allowing an assignation to the Skolithos ichnofacies. This study reveals for
the first time a variability in ichnofacies attributes and distribution at the Rifian Corridor, associated
with turbidites, contourite and shallow marine sediments. Hydrodynamic energy reveals as the
major factor controlling trace maker communities in the studied seaway. Highly energetic conditions
typical of shallower settings are present in deeper-water environments (i.e., slope), contributing to
ichnodiversity impoverishment in ichnofacies.