palaeoechology and taphonomy of Albian-Cenomanian Echinoids of Kazhdumi Formation in Firouzabad section, Zagros Basin
Subject Areas : زمین شناسی نفتBabak Sedghi 1 , Ali Bahrami 2 , Yazdi Yazdi 3
1 - Ph.D. in Paleontology & Stratigraphy, Department of Geology, Faculty of Sciences, University of Isfahan, Isfahan, Iran
2 - دانشگاه اصفهان
3 - professor
Keywords: Kazhdumi, Echinoderms, Taphonomic, Epifauna, Diapirs, ,
Abstract :
Kazhdumi Formation deposits in Firouzabad section were investigated regarding the postmortem and burial events of echinoderms, from about 150 echinoderm fossils which include 10 genera and 13 species of Coenholectypus neocomiensis, Phymosoma binexilis, Dorocidaris taouzensis, Cottaldia aff. Benettiae, Leptosalenia sergipensis, Phymosoma baylei, Micropedina olisiponensis, Tetragramma deshayesi, Macraster douvillei, Mecaster batnensis, Macraster obtritus, Pliotoxaster comanchei, Macraster sp., Hemiaster sp. most part of them suffer from disarticulation and fragmentation, radial cracks and shell deformation (test outline distortion and radial cracking) and volume change and biological erosion (bioerosion) and perforation by living worms (microboring). Of course, after volume changes, fractures or taphonomic compression, the existing solutions (hydrocarbon and solutions rich in iron, manganese and sometimes silica) hydroxides have been replaced in the cracks. The test of these echinoderms has been used by symbiotic epifauna such as Osterids and Gryphaes as food and attachment points and shelter after their death and burial. It seems that the volume change, crushing, solution injection and fauna bending are influenced by the tectonic pressure of the salt domes of the region and the soft lithology (high plasticity) of the Kazhdami formation between the Darian and Sarvak formations.