Abstract

RAHIMINEJAD, Amir Hossein; YAZDI, Mehdi  and  GHOSH, Amit Kumar. Paleoecology of Lower Miocene coralline red algae-rich grainstone facies in the Qom Formation (Vartun section, central Iran). Bol. Soc. Geol. Mex [online]. 2022, vol.74, n.2, A020122.  Epub June 05, 2023. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2022v74n2a020122.

In this paleoecological study we focused on coralline red algae-rich shoal grainstone facies in the Lower Miocene (Aquitanian) carbonates of the Qom Formation in the Vartun section in central Iran. The identified coralline red algae are mainly non-geniculate, although very rare geniculate forms of corallines were also recognized in thin section analysis. The identified algae are represented by Melobesioideae (Lithothamnioncf.valens,Lithothamnioncf.rovereoti,Lithothamnioncf.peleense, andLithothamnionspp.), Mastophoroideae (Neogoniolithonsp.,Spongitesspp., andSpongitescf.fruticulosus),Sporolithonspp. (Sporolithonspp. andSporolithoncf.airoldii), and geniculate coralline (Corallina). The algal taxa mainly display fruticose and lumpy growth forms. The dominance of the former is consistent with high water energy in the identified shoal environment. The presence of Lower Miocene algae indicates that deposition of carbonates took place in warm tropical to subtropical waters in a euphotic marine environment during the Aquitanian. Likewise, high water energy and sediment agitation resulted in taphonomic features such as fragmentation, abrasion, and disarticulation.

Keywords : red algae; rhodophyta; carbonate producers; facies; Miocene; Aquitanian.

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