Peri-Gondwanan acritarchs, chitinozoans, and miospores from Paleozoic succession in the High Zagros Mountains, southern Iran: Regional stratigraphic significance and paleogeographic implications

Abstract

Acritarchs and chitinozoans were documented from Ordovician strata and miospores from Lower Permian beds in the Zardkuh area. Ninety-one palynomorph species, comprising acritarchs (63 species of 31 genera), chitinozoans (16 species of 12 genera), and miospores (12 species of 10 genera) were recognized that form 10 local assemblage zones, comprising Zones A–F= acritarchs, G–I= chitinozoans, and J= miospores. Zone A occurs in the uppermost Ilebeyk Formation, indicating Late Cambrian; Zones B–E are present in the Zardkuh Formation, suggesting Early Ordovician (Tremadocian–Floian)–Middle Ordovician (Dapingian) and Zone F occurs in the Seyahou Formation, presenting Late Ordovician (Hirnantian). Likewise, three Gondwanan chitinozoan Zones G–I were established in this succession. Zones G–H occur in the Upper Shale Member of the Zardkuh Formation, supporting an Early-Middle Ordovician (Floian–Dapingian), and Zone I is restricted to the Seyahou Formation, suggesting Late Ordovician (Hirnantian) age. Finally, Zone J occurs in the Faraghan Formation, confirming Early Permian. Based on palynomorph zones, two hiatuses are present within the Paleozoic sequences of the study area. The first hiatus occurs between the Zardkuh and Seyahou formations, encompassing the Middle Ordovician (Dapingian) and much of the Late Ordovician (Sandbian and Katian). The second hiatus appears between the Seyahou and Faraghan formations, spanning the Silurian, Devonian, Carboniferous, and earliest Permian (Asselian). The palynomorph taxa, including Arbusculidium, Striatotheca, Coryphidium, Vavrdovella, Eremochitina, Velatachitina, and miospore taxa, confirm that the study area belongs to peri-Gondwana paleoprovince. Four new species are Vavrdovella mawlawii sp.nov., Vogtlandia zardkuhensis sp.nov, Pseudocoryphidium zagrosensis gen et sp.nov, and Pterospermella saadii sp.nov.