Statherian-Calymmian (ca. 1.6 Ga) magmatism in the Alto Moxoto Terrane, Borborema Province, northeast Brazil: Implications for within-plate and coeval collisional tectonics in West Gondwana

摘要

We present geochronological, geochemical, and isotopic data on Statherian Calymmian metaplutonites located within the Alto Moxoto Terrane (Borborema Province, Brazil). The Carnoio Suite occurs within a large area of this terrane. It is characterized by slightly deformed syenogranites and quartz-syenites, which present a geochemical signature typical of within-plate magmas. In contrast, the Coloete Suite occurs in the northern border area of the terrane. Its petrographic and geochemical characteristics vary between those of granodiorite and syenogranite, while its geochemistry suggests an arc-related/syn-collisional origin. There are few Statherian A-type granites in the Borborema Province and in its African counterpart. Zircon crystals recovered from the Carnoio Suite (dated 1638 Ma) and from the Coloete Suite (dated 1652 Ma; LA-ICP-MS) provide some clues about magma volume and concentration during the Statherian-Calyrnmian transition. Coeval collisional magmas are scarce in this region: they are interpreted worldwide as a product of peripheral convergences and coeval with the fragmentation of cratonic blocks. Our results suggest that the Alto Moxoto Terrane was part of an ancient block affected by an intraplate event during at the Statherian-Calymmian transition; moreover, its northern limits might have experienced accretion during a crust-reworking episode.