The inception of the Maliac Ocean: Regional geological constraints on the western Circum-Rhodope belt (northern Greece)

Abstract

Abstract Considerable debate surrounds the early-Alpine paleogeographic significance of the Circum-Rhodope belt (CRB, Greece), in particular, whether it was a rifted section of the southern Euroasian foreland, or of the late Mesozoic back-arc system of the Vardar Ocean or of both. In the attempt to clarify the complex nature of the CRB, nine new lithostratigraphic formations (with its members) in consideration of the spatiotemporal and regional geological context are constrained by tracing the changes in regional plate interactions and linked magmato-sedimentary record. The analysis of the stratigraphic data in combination with the highly complex, yet poorly constrained regional geology is employed to reconstruct the late Permian, Triassic, and latest Jurassic developments of this part of the southern European foreland. A continuum between the rifting and Triassic opening of the Maliac Ocean, the Carnian Eo-Cimmerian docking, is supported by the consolidated new data embedded into a collection of the nine distinct lithostratigraphic formations. The terminal Vardar plate approach during the latest Jurassic - earliest Cretaceous and the convergence with the investigated portion positioned to the south of the Balkan-Hellenic foreland thrust belt configured this regional Neotethyan flysch trough, whereas the Paleocene - Eocene east-west shortening and nappe stacking ejected the incoherent early Alpine system referred to as the CRB. The ejected Permo-Triassic, including the early Jurassic ophiolite-bearing formations of the CRB, are matched to be in line with those of the regional Southeast European importance. In fact, the results place the western CRB or eastern Maliac Ocean to lie at the distal southern margin (promontory) of the Eurasian craton aligned with the early- and late Paleozoic crystalline terranes: Paleozoic to Lower Triassic Variscan basement (segment of the Pelagonian Unit), “Veles Series” and Lower Complex of the Serbo-Macedonian Unit (Vertiskos Unit).