Arc-like magmatism in syn- to post-collisional setting: The Ediacaran Angra Fria Magmatic Complex (NW Namibia) and its cross-Atlantic correlatives in the south Brazilian Florianópolis Batholith

Ediacaran syn-tectonic plutonic rocks (amphibole gabbros, quartz diorites/tonalites to biotite- and muscovite-bearing granites) of the Angra Fria Magmatic Complex (Kaoko Belt, north-western Namibia) belong two compositionally similar, magnesian, transitional tholeiitic–calc-alkaline suites, Older (∼625–620 Ma) Younger (∼585–575 Ma). Both have counterparts in broadly contemporaneous Florianópolis Batholith (southern Brazil), from which they were separated during Cretaceous opening southern Atlantic. In Complex, only unequivocal mantle contributions are identified mingling zones Suite hybrid mafic–intermediate dykes uncertain age. Previously published Hf-in-zircon isotopic data, together with new whole-rock geochemical Sr–Nd signatures, underline an important role crustal anatexis a material late Palaeoproterozoic early Mesoproterozoic mean residence (1.9–1.5 Ga). This interval resembles some Nd model ages for Tonian ‘Adamastor Rift’-related felsic magmatic Namibian Coastal Uruguayan Punta del Este terranes. detail, probably originated mainly by fluid-present melting metabasalts metatonalites, followed (near) closed-system fractional crystallization (with or without accumulation) amphibole ± plagioclase. For Suite, principal process was dehydration relatively lower protoliths (metagreywackes intermediate–acid orthogneisses >> metapelites), leaving garnet residue. Based on geological context, conspicuous enrichment hydrous-fluid-mobile large ion lithophile over conservative high field strength elements is not interpreted through classic oceanic plate subduction, devolatilization, fluxed-melting overriding wedge. Instead, it thought reflect high-grade metamorphism deeply buried continental crust attendant water-fluxed overlying lithologies, connected inversion Rift’.