The Novo Progresso Formation, Tapajós Gold Province, Amazonian Craton: zircon U-Pb and Lu-Hf constraints on the maximum depositional age, reconnaissance provenance study, and tectonic implications
Journal of the Geological Survey of Brazil
The Novo Progresso Formation, Tapajós Gold Province, Amazonian Craton: zircon U-Pb and Lu-Hf constraints on the maximum depositional age, reconnaissance provenance study, and tectonic implications
Autor Correspondente: Evandro Klein | [email protected]
Palavras-chave: U-Pb, Hf isotopes, Nd isotopes, Paleoproterozoic, Orosirian, Sedimentology.
Resumos Cadastrados
Resumo Inglês:
The Novo Progresso Formation, located in southeastern Tapajós Gold Province, at its boundary with the Iriri-Xingu Domain, south of the Amazonian Craton, is composed of quartz- and lithic-arenites and siltstones with volcanic/volcanoclastic contributions, and was deposited in fluvial and lake systems. Reconnaissance detrital zircon U-Pb LA-ICP-MS data on a lithic arenite indicate maximum depositional age around 1840 Ma, whereas structural relationships suggest a minimum age of 1780 Ma. The zircon age spectrum shows two well-defined peaks at 1846 and 1968 Ma, and statistically secondary peaks ranging from 2185 Ma to 2973 Ma. εHf values vary from +8.1 to -14.5 (TDM = 2.13 to 3.95 Ga), whereas the εNd values range from -2.5 to -3.3 (TDM = 2.31 to 3.21 Ga), with one positive value of +4.5 (TDM = 1.81 Ga). These data and the lithological composition indicate that surrounding Orosirian rocks from Tapajós and Iriri-Xingu were the main sources for the sediments, with subordinate contributions from older and more distant domains of the Amazonian Craton. In addition, the Hf systematics suggest a ~2.50 Ga-old crustal growth event and a ~3.95 Ga-old hidden component in the eastern portion of the Amazonian Craton. The deposition of the Novo Progresso Formation is related to the development of the large Orosirian intracratonic rift system known as Uatumã Silicic Large Igneous Province (1.89-1.80 Ga), which cut across the Amazonian Craton, following the final stages of magmatism in the Tapajós Gold Province.
