Ages and possible provenance of the sediments of the Capim River kaolin, Northern Brazil.

Abstract

Provenance studies carried out on the soft and flint facies of the Capim River kaolin (northern Brazil) trace the possible sources of sediments that host the ore. Pb–Pb evaporation geochronology was applied to four predominant morphologic classes of detrital zircons, and the ages obtained were compared to the main age intervals of the rocks surrounding the Capim kaolin district (CKD). Four major plateau ages (2.15, 2.02, 1.87, and 1.51 Ga) were defined for both soft and flint facies, indicating a common source for the kaolin and provenance from NE and SW. The 2.15 and 2.02 Ga ages correlate with the granitic bodies of the Gurupi region, located NE of the study area. The 1.87 and 1.51 Ga ages show provenance from the Amazon Craton, the former from the southern portion, in the Caraja´s region, and the latter from the southwestern portion. Although less abundant, Archean (3.18, 2.79, and 2.55 Ga) and Neoproterozoic ages (0.8 and 0.51 Ga) also correlate with the SW and NE provenances, respectively. The first corresponds to the oldest rocks of the Caraja´s region and the second to the rocks of the Gurupi region, corresponding to the Brasiliano orogeny.