Ichnological analysis and depositional setting of late Miocene marginal marine deposits from the Tafna Basin (northwestern Algeria)


 
 The late Miocene marginal marine deposits of Sikkak area(Tafna Basin, northwestern Algeria) encompass moderately diversified invertebrate trace fossils preserved mainly as epichnia. The present study documents for the very first time the trace fossils occurring in this area, where16 ichnotaxa, dominated by post-depositional domichnial, repichnial and fodinichnial components, are reported: ?
 Bifurculapes
 isp.,
 Diplocraterion
 isp.,
 Helminthoidichnites
 isp., ?
 Kouphichnium
 isp., ?
 Megagrapton irregulare
 ,
 Ophiomorpha annulata, O.
 cf.
 nodosa
 ,
 Oravaichnium
 isp.,
 Palaeophycus
 isp.,
 Planolites
 cf.
 beverleyensis
 ,
 P. montanus
 ,
 Ptychoplasma
 isp.,
 Skolithos
 isp.,
 S. linearis
 ,
 Thalassinoides
 isp. and
 T. suevicus
 . The main producers of the studied trace fossils are arthropods (crustaceans, limulids, insects), annelids (polychaetes, phoronids) and bivalves. These traces are commonly associated with sedimentary structures that are caused by hydrodynamics, suggesting high energy conditions and opportunistic colonization within a marginal marine environment (i.e., backshore to foreshore), and corresponding to the
 Skolithos
 ichnofacies. The crustacean trace ?
 Bifurculapes
 as well as the limulid trackways
 Kouphichnium
 are reported herein for the first time in Algeria. Sedimentological data suggest an imbricated sandstone channels within a marginal marine setting and subaerial exposures indicated by mud-cracks. Thus, the foraminiferal assemblage, dominated by shallow marine species, suggests a Tortonian age for these deposits.
