Detrital zircon U-Pb geochronology of the Maricá Group: Sources areas and maximum depositional age
Geocronologia U-Pb de Zircão Detritíco do Grupo Maricá: Áreas Fontes e Idade Máxima de Deposição
DOI:
https://doi.org/10.5016/geociencias.v41i1.16286Abstract
The Maricá Group is the basal unit of the Camaquã Basin and comprises mainly fluvial deposits and shallow marine beds. Provenance studies of the Maricá Group are crucial to understanding the initial development of this basin. This paper aims to present new LA-ICP-MS U-Pb provenance data for the evaluation of the source areas and the maximum depositional age of the Maricá Group. This work includes fieldwork recognition, petrographic analysis, and U-Pb dating of one sandstone and two clasts samples, from the Arroio América Formation, the youngest unit from Maricá Group. The Arroio América Formation was deposited on a braided fluvial system and is composed of sandstones, conglomeratic sandstones, and conglomerates rocks. The sandstone and the sandstone clast display a similar zircon age range and pattern. They are derived from mixed sources (599 – 3025 Ma) with a major contribution of Syderian (2422 Ma), Ediacaran (621 Ma), and Statherian (1749 Ma) sources. Minor contributions from Ryacian (2212-2040 Ma) and Archean (2823-2503) are also present. The Ediacaran sources are related to Ediacaran granites from Bagé Region as the Santo Afonso Suite. The maximum depositional age of the sandstone was constrained at 599.8 ± 11.5 Ma and the sandstone clast at 619.4 ± 11 Ma. The similarity between the sandstone and the clast ages shows that portions of this basin and probably the Maricá Group itself served as a source of sediments, indicating a dynamic setting with deposition, burial, uplift, and rework in a short time.
