Sedimentological and ichnological signatures of an offshore-transitional hyperpycnal system (Upper Miocene, Betic Cordillera, southern Spain)

Hyperpycnal flows have been widely described in different lacustrine and marine environments but sedimentary structures fossil content hyperpycnites often offer limited information about the palaeoenvironmental conditions. This limitation can be improved by ichnological analysis, which has recently used as a tool to differentiate between type of subaqueous deposits, even though still only few detailed studies on exist. In order bridge this gap knowledge, 50 m-thick package terrestrial organic debris-rich, dominantly structureless well-sorted sandstone bodies alternating with burrowed siltstones (Upper Miocene, Betic Cordillera, Spain) is here analyzed. study based observations well-exposed outcrop cores from well drilled just behind field-scale observational gaps. Two sandbodies were typified basis their stratigraphic architecture, physical structures, ichnofacies fine-grained deposits embedding them: (1) Lobate channelized-top sandstones embebbed into silty sands dominant highly variable degree bioturbation Taenidium Schaubcylindrichnus (depauperate Cruziana ichnofacies) interpreted proximal sustained prodelta settings; (2) channelized-lobate (cut-and-fill sequence) Nereites Phycosiphon (Nereites distal developed offshore settings. The studied succession represent progradation sandy hyperpycnal system along starved setting high variability grain-size, benthic food oxygen content. Results suggest that multi-scale analysis focused trace fossils signatures needed get better understanding these river-derived sustained-flow turbidites (hyperpycnites) are less known than conventional surge-type turbidite counterparts.