Facies description of contourites in the Southern Riffian Corridor, Morocco

Abstract

Despite being common in present-day deep-marine environments, ancient contourite drift deposits in outcrop, often referred to as; fossil contourites, are extremely rare. In fact, only 7 have been confidently identified in the ancient stratigraphic record (Stow et al. 1998; Fig 1). One of these outcrops will be the destination of this fieldtrip: the Miocene Ben Allou formation in the Southern Riffian Corridor, Morocco. In recent years, there has been a surge in scientific interest for contourite deposits partly because there are significant gaps in our understanding and partly due to potential economic implications. This increase in attention has improved our understanding of contourites mainly as observed in seismic and core data. However, because of their rarity, contourites in outcrop are known to be much understudied (Rebesco et al, 2014). This is despite the fact that they are relevant to a wide range of subjects across the Earth Sciences as they 1). Record paleoclimate changes 2). Record changes in deep-ocean (geostropic) currents 3). Give insights into shallow to deep marine sediment processes 4). Coastal defense strategies due to sea level rise (Dulfer et al. 2014) 5). Reservoirs and seals in the context of hydrocarbon exploration. Sandy contourites in particular, may be of interest to hydrocarbon exploration for having good reservoir properties and are currently under investigation by Exxon offshore West Africa. All of these implications will benefit from further study of outcrop examples as these permit laterally extensive sampling and logging, thus solving the limitations of core data as well as the low resolution of seismic data. The Ben Allou formation in Morocco is of particular interest, not simply for being sandy in nature, but also for being relatively young with well-established biostratigraphic time constraints, being undistorted by tectonics and having nearby modern analogues of active contourite systems in the Gulf of Cadiz, allowing researchers to compare and contrast the ancient sediments with active modern analogues.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects