Evolution of late Neoproterozoic to early Paleozoic tectonic elements in Central and Southeast European Alpine mountain belts: review and synthesis

Abstract

Late Neoproterozoic to early Paleozoic, Cadomian tectonic elements are widespread in the southeastern Alpine–Mediterranean mountain belts, with discontinuous exposure extending from the Alps to the Menderes Massif in Turkey. The sequences include voluminous plutonic island and continental arc successions, some ophiolites of variable, late Neoproterozoic and Cambrian to early Ordovician ages, high- to medium-grade metamorphic sequences and subordinate metasediments. Geological and geochronological data suggest that these Cadomian elements partly experienced tectonothermal activity including metamorphism and magmatism between ca. 650 and 600 Ma, followed by further I- and S-type plutonism in an Andean-type continental margin setting ca. between 570 and 520 Ma. Subsequently, a major rift zone developed which resulted in continental stretching and subsequent formation of a back arc basin which is dated as late Cambrian. Rifting is followed by oceanic spreading which commenced ca. at the Cambrian/Ordovician boundary, possibly in a back-arc setting. This tectonic scenario suggests that Alpine–Mediterranean Cadomian tectonic elements were accreted to Gondwana during early Cadomian events (ca. 600–650 Ma). Subsequently, they were likely part of a long-lasting ‘outer’ subduction zone of Gondwana at the margin of a Panthalassa-type ocean during late Neoproterozoic III and Cambrian. Due to back-arc spreading, continental pieces started to split off from Gondwana ca. at the Cambrian–Ordovician boundary.