Microfacies and species richness analysis of upper Bartonian and Priabonian carbonate shelf deposits from the Thrace Basin (Tethyan Ocean, Greece): Paleoenvironmental evolution and species-richness hotspot revealed

Abstract

Sediment, thin section, microfacies and foraminiferal analyses were conducted on middle-upper Eocene carbonate deposits to shed new light on the paleoenvironmental evolution and species richness of the Thrace Basin (Tethyan Ocean, Greece). Material from a total of 7 new sites, covering localities on the mainland and the north-eastern Aegean islands of Samothraki and Lemnos, was examined in order to analyze the general conditions and environmental evolution of the basin over as large a geographical area as possible. Analysis of the sedimentological and paleontological data allowed the identification of 5 microfacies types. These can be assigned to a sequence of interior to outer shelf environments and speak in favor of a model of a rimmed carbonate shelf with isolated platforms. Both open and restricted water circulation patterns have prevailed on and between the platforms. Triggered and driven by dynamic syn-rifting, topographic highs have developed in this area on which productive and species-rich reef structures could thrive. In the late Eocene carbonate deposits we found the highest documented species richness of larger symbiont-bearing foraminifers (LBF) to date, characterizing the Thrace Basin not only as a particularly species-rich and diverse area, but also as a LBF hotspot of diversity.