Tectonic setting of the Mesozoic Pindos basin of the Peloponnese, Greece

Abstract

Summary The Pindos isopic zone of western Greece comprises a 1 km thick sequence of Mesozoic and early Tertiary deep water sediments now preserved in a series of imbricate thrust slices in the Central Hellenic Nappe. This paper examines the question as to whether the basement to the Pindos Zone was oceanic or continental crust. Mid-Triassic volcanic rocks around the margins of the Pindos basin suggest initial development as a back-arc basin by subduction of Mesogea beneath Apulia. There is then no volcanic record through the Late Triassic, but tuffs are widespread in the Jurassic. Rare lavas and pyroclastics of Late Jurassic or earliest Cretaceous age are shown by new chemical analyses to be mid-ocean ridge type basalts associated with calc-alkaline andesites and dacites characteristic of subduction. This close juxtaposition of such rock types suggests a back-arc basin setting. Thus at least part of the Pindos Zone appears to have been underlain by oceanic crust. This Late Jurassic oceanic basin is probably tectonically unrelated to the earlier mid-Triassic basin.