Three distinctive feeder‐lobe systems within one time slice of the Tortonian Tabernas fan, SE Spain

Abstract

ABSTRACTExcellent exposures and the presence of lithological markers make it possible to reconstruct the fan facies pattern for a narrow (6000–60 000 yr), late Tortonian (7–8 Ma) time slice of a submarine fan complex that developed in the Tabernas basin. Unlike most classical fan models, which seem to refer to a single feeder‐lobe system, the reconstruction from the Tabernas basin reveals at least three distinctive juxtaposed feeder‐lobe systems: (I) a straight feeder valley terminating in a sandstone body consisting of stacked sand‐filled scours (sand‐rich system); (II) a straight feeder channel diverging in a broad front of nested scours in mudstones. These scours terminate in fine grained sheet‐like turbidite deposits (muddy system); (III) a sinuous channel complex extending far into the basin without ‘lobe’ deposits at its mouth (solitary system).Sedimentary features indicate that in the Tabernas basin, initial basin floor morphology and mass‐flow transport behaviour controlled and eventually stopped formation of the sand‐rich system (I), while depositional topography and slope instability controlled formation of the muddy system (II). The unusual narrowness (10–30 m) and length (8 km) of the solitary system (III) points to its confinement, possibly a result of an intrabasinal fault escarpment trending obliquely to the general direction of slope. Flow stripping (Piper & Normark, 1984) could then explain the absence of a lobe at the channel terminus.