Late-Proterozoic to Paleozoic history of the peri-Gondwana Calabria-Peloritani Terrane inferred from a synthesis of zircon chronology

ABSTRACT Amalgamation and break up of supercontinents and superterranes (Rodinia, Gondwana, Pangea) characterize the history of the Earth between Neoproteozoic and Palaeozoic times. All geological processes known today, starting with Rodinia fragmentation and culminating with the assemblages of Pangea, have been the focus of research in recent decades. Records of magmatism, sedimentation, metamorphism and anatexis accompanying the evolution of the superterrane Gondwana are preserved in some tectonic units of the nappe structured Calabria-Peloritani Terrane reworked by the Variscan and Alpine orogenies. This exotic terrane, according to the most recent paleogeographic reconstructions, was one of the peri-Gondwanan blocks comprising the “Galatian superterrane”. A large number of geochronological data obtained using microbeam techniques, together with previous data collected through traditional methods are today available on different rock types exposed in Calabria-Peloritani Terrane. These data, together with the zircon grain growth textures revealed by SEM imaging (cathodoluminescence -CL and variable pressure secondary electron -VPSED) and the REE-U-Th distribution in the zircon domains were considered in this paper. In particular, U-Pb analyses of zircon from 10 samples of augen gneisses, 8 mafic and intermediate metaigneous rocks and 6 metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) have been considered to define the peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the Variscan orogeny. The zircon grains of all considered samples preserve a Proterozoic memory suggestive of detrital, metamorphic, and igneous origin. The available data fit a frame involving: (1) Neoproterozoic detrital input from cratonic areas of Gondwana; (2) Pan-African/Cadomian assemblage of blocks derived from East and West African Craton; (3) metamorphism and acidic -basic magmatism between 593 Ma and 526 Ma, within an active margin setting; (4) rifting and opening of Ordovician-Silurian basins fed by detrital input from the assembled Cadomian blocks recording provenance from both East and West Gondwana cratonic areas. The Paleozoic basins evolved through sedimentation, metamorphism and magmatism until the Variscan orogeny involving Palaeozoic and pre- Paleozoic blocks. The Proterozoic records decidedly decrease in the high grade metamorphic rocks affected by pervasive partial melting and high temperature of metamorphism.