Sedimentary provenance and U-PB detrital zircon in the mesozoic record of the Parecis Basin, Rôndonia and Juruena sub-basin

Abstract

Sediment provenance analysis is a tool increasingly used in the study of basins. This technique allows identifying the mineralogical and lithological composition of source areas, inferring paleogeography, climate and relief, determining the main sand distribution routes, and estimating the distance and transport time. The Mesozoic volcanic-sedimentary packages of the Parecis Basin mark a significant part of the South American Platform evolution, regarding tectonism, subsidence, sedimentation, basic and alkaline magmatism, uplift and erosion. Also, these packages registers the initial stages of Andean Orogeny subduction. Different authors have established opposite stratigraphic proposals for Parecis Basin regional correlations, and also for its tectonics evolution. Given this context, there are controversies regarding the chronostratigraphic positioning and relationships between the intervals, especially the units called Salto das Nuvens and Utiariti formations. This article presents the faciological framework and facies association, heavy mineral assemblage, ZTR index and sediment sources, and U-Pb detrital zircon ages to both sub-basins. Detrital Zircon data reveal minimum ages of 124 Ma for the Rondônia sub-basin and 245 Ma for the Juruena sub-basin for sedimentary deposition attributed to the base of the Cretaceous units. The detrital age of zircons points to a varied contribution, between elements from different provinces and ages of the Amazon Craton, the Paraguay Fold Belt and records of alkaline magmatism of ages Permo-Triassic and Cretaceous in the different kimberlithic fields of Rondônia and Mato Grosso.