Age, provenance and tectonic setting of metasedimentary sequences of the Gurupi Belt and São Luís cratonic fragment, northern Brazil: Broadening the understanding of the Proterozoic-Early Cambrian tectonic evolution

Abstract

Geological, U-Pb (detrital zircon), whole-rock Nd isotopes, and geophysical information constrain the timing, provenance, and depositional and tectonic settings of sedimentary successions from the Gurupi Belt (GB) and São Luís cratonic fragment (SLCF) in northern Brazil. The results, along with published information about the magmatic events are used to discuss the crustal framework and regional correlations. We defined the following stages of sedimentation related to the Rhyacian and Neoproterozoic-Early Cambrian evolution. (1) 2240–2160 Ma –metavolcano-sedimentary sequences formed in arc- (SLCF) and back-arc (GB) basins. (2) 2165–2120 Ma – two syn-orogenic, siliciclastic (turbidite) sequences; the oldest (>2149 Ma) formed in a forearc or intra-arc setting, the youngest (>2116 Ma) formed in forearc or distal intra-arc system. (3) 2120–2088 Ma – post-collisional, continental, siliciclastic basin(s) formed in fluviatile setting, and representing a foreland system, which was split into two sub-basins in more recent times. These Rhyacian sequences correlate with similar successions in the West-African and Amazonian cratons, and formed during the agglutination of a continental block in pre-Columbia times (>2000 Ma), which remained joined through the assembly (~1800 Ma) and breakup (~1300 Ma) of Columbia, being only fragmented during Rodinia breakup (~750 Ma). This breakup produced, probably distal, intracontinental effects that led to the deposition of (4) 1130–740 Ma – siliciclastic sequences formed in rift and passive margin basins; no evidence of oceanization is observed, and the sequences correlate in time with sedimentary formations of the Rokelide Belt in West Africa. The closure of the epicontinental sea took place during intracontinental orogeny, which represents a distal effect of the collisional orogenies that assembly West-Gondwana at the Neoproterozoic-Early Cambrian boundary. The last sedimentation event comprises (5) < 591 Ma – a post-orogenic/post-collisional siliciclastic basin formed in a rift that might also have been acted as a precursor rift of the Phanerozoic intracratonic basins.