The clastic record of an early Brasiliano Orogeny; pre-collisional subduction-related metamorphism within the southern Borborema Province through detrital rutile analysis

The ubiquity of detrital zircon in clastic sediments made zircon one of the primary minerals for provenance and tectonomagmatic studies. Its high U-Pb closure temperature (>900oC), limited growth of new zircon under upper amphibolite-eclogite facies, inherited bias towards felsic sources, and the refractory behavior rarely representing first-cycle sedimentation can hamper the detection of key tectonomagmatic events. Other mineral assemblages, like rutile, formed in medium- to high-grade metapelite and metabasite during high-pressure and low-temperature subduction metamorphism can help to provide a complete record of polyphase orogenic evolution. In this study, we present U-Pb ages and trace elements in detrital rutile from the Ordovician Tacaratu Formation (Tucano-Jatoba Basin) to track the complete polyphase evolution of southern Borborema Province. Coupled U-Pb detrital zircon and rutile analysis revealed that detrital zircon ages lag detrital rutile ages by ca. 100 Ma. Three rutile age peaks at ca. 767 Ma, 669 Ma, and 595 Ma were recognized, agreeing with subduction in magma-poor orogenic phases (lulls) between relatively high magma generation phases (flare-ups). The detrital rutile ages record earlier phases of Brasiliano Orogeny in southern Borborema Province (subduction-related metamorphism; closure of Sergipano Ocean), since this orogeny culminated in the collision of blocks followed by high-temperature metamorphism.