Palaeoenvironment of Eocene prodelta in Spitsbergen recorded by the trace fossil Phycosiphon incertum

Ichnological, sedimentological and geochemical analyses were conducted on the Eocene Frysjaodden Formation in order to interpret palaeoenvironment prodelta sediments in the Central Basin of Spitsbergen. Phycosiphon incertum is the exclusive ichnotaxon showing differences in size, distribution, abundance and density, and relation to laminated/bioturbated intervals. Large P. incertum mainly occur dispersed, isolated and randomly distributed throughout the weakly laminated/non-laminated intervals. Small P. incertum occur occasionally in patches of several burrows within laminated intervals or as densely packed burrows in thin horizons in laminated intervals or constituting fully bioturbated intervals that are several centimetres thick. Ichnological changes are mainly controlled by oxygenation, although the availability of benthic food cannot be discarded. Changes in oxygenation and rate of sedimentation can be correlated with the registered variations in the Bouma sequence of the distal turbiditic beds within prodeltal shelf sediments.Funding for this research was provided by Project CGL2012-33281 (Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain), Project RYC-2009-04316 (Ramón y Cajal Programme) and Projects RNM-3715 and RNM-7408 and Research Group RNM-178 (Junta de Andalucía). The authors benefited from a bilateral agreement between the universities of Granada and Oslo, supported by the University of Granada