The evolution of the Earth and its processes to sustain life have been a major research topic during the past decades. Questions regarding the planet's habitability, including when the ocean and the atmosphere became oxygen-rich, still imposes challenges to our understanding of how and when these resources evolved. This increase in atmospheric oxygen through Earth's history modulated an evolutionary trend that may have affected and/or delayed the evolution of life. The geological record, particularly iron formations and shales from the Archean/Paleoproterozoic to the Neoproterozoic, are well-suited archives to further explore such relationships before, during and after the rise of atmospheric oxygen. The aim of this study is to understand changes in the redox-state of the ocean-atmosphere system during periods of oxygenation (e.g. whiffs, GOE, and NOE) through trace element abundances (e.g. Mo, Cr and U), and isotope compositions of Fe and Zn from iron formations (IF), organic matter-rich shales (black shales), and in situ Fe isotopes on selected samples from the Carajás mineral province (CMP), Pará Region, and the Santa Cruz Iron deposit of the Jacadigo Group, Mato Grosso do Sul. In addition, Zn isotopes will be analyzed in the previous well-studied samples from Turee Creek, Australia, and by combining these methods, we expect to shed light into the evolving redox state of the early Earth.
News published in Agência FAPESP Newsletter about the scholarship: