Paleoecological evaluation of the graphoglyptids of the Eocene flysch deposits, west of Khash, southeast Iran, regarding the event sedimentation

Extensive outcrops of Eocene flysch deposits are available in the Khash area, south-east Iran. These flysches comprise sedimentary cycles of marl, shale, siltstone, and sandstone with erosional structures such as groove and flute casts. The studied sediments are deposited as a result of event-sedimentation. Diverse graphoglytids have been collected from an outcrop of these sediments, located 15 Km west of Khash. Seventeen ichnogenera have been determined among the studied deposits. Most of these trace fossils were formed in the pre-event sedimentation phase on the muddy substrates, and they include Desmograpton, Helminthorhaphe, Paleodytion, Protopaleodictyon, Scolicia, Spirophycus, Spirorhaphe, Squamodictyon, Urohelminthoida. Post-event trace fossils are low in ichnodiversity and form in the sandy or silty substrates, they consists of Halopoa, Helicodromites, Helminthopsis, Nereites, Paleomeandron, Phycosiphon, and Planolites. Some of the trace fossils such as Paleodictyon are aligned with respect to the paleocurrent directions, and were affected by the currents. It seems that fine-grained pre-event sediment surfaces was favorite for K-strategist, while post-event sediments were occupied by R-strategist trace-makers.