Geochemical and detrital zircon geochronological investigation of the metavolcanosedimentary Araticum complex, sergipano fold belt: Implications for the evolution of the Borborema Province, NE Brazil

摘要

The Borborema Province is an important Precambrian orogenic system in Northeastern Brazil. It was formed during the assembly of Western Gondwana in the Brasiliano-Pan-African Orogeny. The Neoproterozoic Sergipano Belt is part of the Province and occupies a large area of its southern portion. Investigation of provenance and tectonic environment of the metavolcanic-sedimentary complexes in this belt are of regional amplitude and may reveal important aspects of the evolution of the province. In this study new whole-rock geochemistry, isotope Nd data and U-Pb geochronological data on detrital zircon of the metavolcanic-sedimentary Araticum Complex within the northeastern part of the Sergipano Belt, in order to contribute to the understanding the role of the Sergipano Belt in amalgamation of Western Gondwana. The related data indicate provenance from eroded island arcs and back-arc-relate settings during the Neoproterozoic. Detrital zircon grains indicate populations of Ediacaran-Cryogenian (ca. 660-620 Ma) and Tonian-Stenian ages (around ca. 1047 Ma) suggesting that source areas represent extinct volcanic arcs of the Pernambuco-Alagoas Domain to the north. Based on this study, it is suggested that sediments of the Araticum paleobasin were deposited in an oceanic environment during the arc exhumation over the Brasiliano-Pan African Orogeny, but also with strong contributions from Stenian island arcs, which are attributed to the Cariris Velhos Orogeny. Our results support that major supracrustal sequences of the Sergipano Fold Belt were deposited in the Neoproterozoic, such as indicated by previous studies.