Neoproterozoic pre-collisional events recorded in the Sergipano belt, Southern Borborema Province, West Gondwana

Abstract

ABSTRACT The Canindé Domain is crucial for understanding the pre-collisional events in Sergipano Belt, Borborema Province, especially during the Late Stenian/Early Tonian (740–680 Ma). We present thermobarometric, geochronology, and isotopic studies of the metavolcanosedimentary rocks of the Novo Gosto unit. The calculated metamorphic conditions resulted in a range of T: 600–740°C and P: 3.5–10.0 kbar for non-mylonitic amphibolites and values of T: 636–808°C and P: 7.0–12.0 kbar for mylonites, both of amphibolite facies. The minimum metamorphic conditions imprint in these rocks are T: 390°C and P: 2.5 kbar, indicating retrometamorphism in greenschist facies. The probable age of the peak metamorphic event was obtained in zircon rims from a quartzite at 692 ± 8.5 Ma. U-Pb detrital zircon and Nd model ages of the metasedimentary rocks point out Early Tonian as primary source rocks. Subordinate contributions of Mesoproterozoic, Paleoproterozoic, and Neoarchean sources were also recognized. These primary sources are related to Cariris Velhos event rocks, whereas the subordinate sources are from the Pernambuco-Alagoas superterrane. Early Tonian and Late Stenian ages were recognized for the first time in the Canindé Domain, with U-Pb zircon ages of 1005 ± 3 and 989 ± 6 Ma in amphibolites and mylonitized granites, mostly outcropping at the southwestern limit of the area. New ages were also obtained in the Novo Gosto surrounding intrusions: Canindé Layered Gabbroic Intrusion (~718 Ma), Garrote (~715 Ma) and Curralinho/Boa Esperança (~708 Ma) metagranites, and Gentileza metavolcanic rock (~700), which integrate the early pre-collisional magmatism of the Sergipano Belt (~740-680 Ma). Finally, U-Pb zircon ages were obtained in the Poço Redondo Domain, potential source area of the Novo Gosto metasedimentary rocks, resulting in ages of 957 ± 11 and 988 ± 15 Ma. The new data bring perspective to future correlations with adjacent belts and the understanding of the structuration of West Gondwana during the Brasiliano-Pan-African Orogeny.