Ediacaran rocks from the Cadomian basement of the Saxo-Thuringian Zone (NE Bohemian Massif, Germany): age constraints, geotectonic setting and basin development

Abstract

AbstractThis paper is focused on a compilation of known data from the low-grade metamorphosed rocks of the Ediacaran period in the German part of the Saxo-Thuringian Zone at the northeastern margin of the Bohemian Massif. The geotectonic setting during the formation of Ediacaran rock units is characterized by Cadomian orogenic processes from c. 650–540 Ma at the periphery of the West African Craton. The basin development during that time is characterized by the formation of a Cadomian backarc basin with a passive margin, and the outboard sitting Cadomian magmatic arc originated at c. 570–560 Ma. This arc-marginal basin system was formed on stretched continental crust in a strike-slip regime and reflects an active-margin setting in a style similar to the recent West Pacific. The backarc basin was closed between c. 560–540 Ma by the collision of the Cadomian magmatic arc with the cratonic hinterland: this resulted in the closure of the backarc basin and the formation of a Cadomian retroarc basin. Collision of an oceanic ridge with the Cadomian Orogenic Belt led to a slab break-off of the subducted oceanic plate resulting in an extreme heat flow, and a magmatic and anatectic event culminating at c. 540 Ma that was responsible for the intrusion of voluminous granitoid plutons.