Paleoecology, bioerosion, and paleoenvironments in the Late Miocene of Dar Pahn Unit, Makran, SE Iran

This study focuses on sedimentation patterns and paleoecological conditions during the Upper Miocene in Southeast Iran, specifically analyzing the Rudig section. The sedimentation was predominantly terrigenous and occurred in marine conditions, forming multiple shallowing upwards sequences comprising silty marl, siltstone, and sandstone. The analysis of molluscan shells from this period indicates minimal bioerosion, with encrusters represented solely by Balanus sp. This low level of encrustation suggests rapid sedimentation and brief exposure times. Bioerosion was limited, with Caulostrepsis taeniola borings found only in the shells of vermetid Thylacodes sp. and predatory gastropod Conus sp. Predatory drillings, identified as Oichnus paraboloides were present in the shells of Turritella sp., Corbula sp., and Bursa sp., along with occasional shell aperture peeling repairs in Turritella sp. The presence of abundant large Thalassinoides burrows in the sandstone facies, along with moderate ichnodiversity supports the interpretation of the sandstone facies as shoreface. The rare occurrence of Ophiomorpha nodosa in siltstone facies, and the dominance of burrowing crustaceans in shallow water facies and suspension-feeding mollusks in deeper facies, provides further insight into the paleoenvironment. This study offers a detailed reconstruction of the sedimentary and ecological dynamics during the Upper Miocene in this region, enhancing our understanding of paleoenvironmental conditions and faunal interactions. Keywords: biofacies, sedimentary facies, bioerosion, encrustation, predation, Cenozoic.