An early Rupelian origin of Titanoderma pustulatum recorded in the Qom Formation, Iran

• Main Authors: Basso, D, Coletti, G, Bracchi, VA, Yazdi-Moghadam, M
• Other Authors: Bracchi, V
• Format: Conference Object
• Language: English
• Published: Birbal SahniInstitute of Palaeosciences 2019
• Subjects: Coralline algae; Oligocene; Iran; palaeoecology; biostratigraphy; GEO/01 - PALEONTOLOGIA E PALEOECOLOGIA; Elliot; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10281/245490

The Rupelian Uromieh section of the Qom Formation consists of Nummulites-bearing limestones that overlay thick polymictic conglomerates and are overlaid by marlstones rich in planktonic foraminifera. The section was analyzed with the aim to provide a first description of its still unknown coralline algal assemblages, and for depicting its benthic paleoecological evolution through time. The early to middle Rupelian age has been constrained by the occurrence of Nummulites fichteli Michelotti, Nummulites vascus Joly & Leymerie, Halkyardia maxima Cimerman and Subterraniphyllum thomasii Elliot, along with the absence of Nephrolepidina Douvillé and Eulepidina Douvillé. A proximal inner-platform environment is reconstructed for the lower part of the section, based on the abundance of miliolids and corals, while upsection the increase in large rotaliids, coralline algae and bryozoans points toward a distal inner-platform/proximal middle-platform setting. Coralline algal assemblages support this interpretation, with Sporolithales and Hapalidiales becoming more common in the upper part of the section. Within the coralline assemblage, Lithoporella melobesioides Foslie and Titanoderma pustulatum (Lamouroux) Nägeli are two of the most common species, together with articulated coralline algae. Among the latter, S. thomasii is more common in coral-rich intervals. The specimens of T. pustulatum recovered in the Uromieh section predate all the other known records of this species, indicating that the origin of T. pustulatum should be dated at least at the early Rupelian.