Neoproterozoic mantle connections during the West Gondwana assembly in the Vazante Carbonate Platform, Central Brazil

Abstract Post-collisional mafic-ultramafic magmas provide significant insights into continental extension, including tectonic processes, sources, and geochronological constraints. Here, we report the first Neoproterozoic geochronological data for mafic-ultramafic dikes that cross-cut the Vazante carbonate-dominated sequence on the West Gondwana platform, Central Brazil. Although these dikes have been previously dated, the Neoproterozoic generation had not been identified. These dikes exhibit positive εNd(t) values and a tholeiitic to alkaline affinity, supporting a mantle-derived source. The 591 ± 11 Ma dikes were emplaced during the final transition from a ductile continental collision regime to a brittle extension regime, characterized by the ascent of mantle-derived melts through crustal structures during the late assembly of West Gondwana. This transition led to the development of a system of sinistral NE-trending faults that acted as deep channels for metalliferous fluid percolation following the continental collision. Our findings establish a minimum depositional age for the Vazante Carbonate Platform, which was a long-standing challenge.