Contourite depositional system after the exit of a strait: Case study from the late Miocene South Rifian Corridor, Morocco
Metadatos
Afficher la notice complèteEditorial
Wiley-Blackwell Publishing
Materia
Bottom currents Channels Contourites Deep-water sedimentation Late Miocene Morocco Rifian corridors Tides
Date
2021-04-25Referencia bibliográfica
de Weger, W... [et al.] (2021), Contourite depositional system after the exit of a strait: Case study from the late Miocene South Rifian Corridor, Morocco. Sedimentology. [https://doi.org/10.1111/sed.12882]
Patrocinador
Office National des Hydrocarbures et des Mines (ONHYM), Morocco; TOTAL; BP; ENI; ExxonMobil; Wintershal DEA; TGS; "The Drifters Research Group" at Royal Holloway University of London (RHUL) CTM 2012039599-C03 CGL2016-80445-R CTM2016-75129-C3-1-R; Ministerio de Educacion, Cultura y Deporte (Gobierno Espana)Résumé
Idealized facies of bottom current deposits (contourites) have been established
for fine-grained contourite drifts in modern deep-marine sedimentary environments.
Their equivalent facies in the ancient record however are only scarcely
recognized due to the weathered nature of most fine-grained deposits in outcrop.
Facies related to the erosional elements (i.e. contourite channels) of contourite
depositional systems have not yet been properly established and
related deposits in outcrop appear non-existent. To better understand the sedimentary
facies and facies sequences of contourites, the upper Miocene contourite
depositional systems of the South Rifian Corridor (Morocco) is
investigated. This contourite depositional system formed by the dense palaeo-
Mediterranean Outflow Water. Foraminifera assemblages were used for ageconstraints
(7.51 to 7.35 Ma) and to determine the continental slope depositional
domains. Nine sedimentary facies have been recognized based on lithology,
grain-size, sedimentary structures and biogenic structures. These facies
were subsequently grouped into five facies associations related to the main
interpreted depositional processes (hemipelagic settling, contour currents and
gravity flows). The vertical sedimentary facies succession records the tectonically
induced, southward migration of the contourite depositional systems
and the intermittent behaviour of the palaeo-Mediterranean Outflow Water,
which is mainly driven by precession and millennial-scale climate variations.
Tides substantially modulated the palaeo-Mediterranean Outflow Water on a
sub-annual scale. This work shows exceptional examples of muddy and sandy
contourite deposits in outcrop by which a facies distribution model from the
proximal continental slope, the contourite channel to its adjacent contourite
drift, is proposed. This model serves as a reference for contourite recognition
both in modern environments and the ancient record. Furthermore, by establishing
the hydrodynamics of overflow behaviour a framework is provided that
improves process-based interpretation of deep-water bottom current deposits.