اثرشناسی سازند جیرود در رخداد انقراض هانگنبرگ (فامنین- تورنزین)، برش ‏زایگون، البرز مرکزی ‏

A detailed ichnological study on the geirud formation (late devonian-early carboniferous) from the zaygon area, central ‎alborz shows a diverse trace fossils, which include 14 ichnogenera represented by 23 ichnospecies. these trace fossils ‎contains various ethological patterns, such as domichnia, fodinichnia, grazing, equilibrichnia, and fugichnia. these trace ‎fossils are: arenicolites, asterosoma,‎‏ ‏chondrites intricate,‎‏ ‏chondrites targionii,‎‏ ‏diplocraterion parallelum,‎‏ ‏arenicolites isp., ‎asterosoma isp., chondrites intricate,‎‏ ‏chondrites targionii, chondrites isp.,‎‏ ‏diplocraterion parallelum, helminthoidichnites ‎isp., helminthopsis abeli, helminthopsis isp.,‎‏ ‏palaeophycus heberti, palaeophycus tubularis,‎‏ ‏planolites beverleyensis, ‎planolites isp., phycodes cf. palmatus,‎‏ ‏rhizocorallium jenense, rhizocorallium irregular,‎‏ ‏rosselia soccialis, taenidium ‎serpentinum,‎‏ ‏taenidium satanassi, talassinoides horizntalis,‎‏ ‏thalassinoides suevicus,‎‏ ‏thalassinoides paradoxicus, ‎‏ ‏zoophycos isp.‎‏ ‏‎ studied beds consist by alternations of laminated mudstones and siltstones, and thick- to medium-bedded ‎sandstones with wavy lamination. hummocky, trough and low angle to planar cross-bedding are common in layers. it seems ‎that these beds were deposited in the delta to open marine environments.‎‏ ‏determined ichno-assemblage represents ‎characteristic of a moderately shallow-marine environment, which effected occasionally by high-energy conditions. a trace ‎fossil assemblage has been examined from the‏ ‏uppermost dark-colored shale layers of the geirud formation in the ‎devonian/carboniferous (d-ca) boundary. this assemblage include chondrites targionii, zoophycos isp., which involved by ‎hangenberg event. ‎