A multiple isotope and trace element approach to constrain the oxygenation and metal cycling of 3.5 to 3.2 Ga paleo-oceans

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Geochemical proxies for the oxygenation of and metal cycling in the hydrosphere, such as Mo, U, Re-Os, S and Fe isotopes can be used to establish the spatiotemporal distribution of these elements in Paleo-oceans, which is inextricably linked to the evolution of life on Earth, by using well-dated and well-preserved marine sediments. However, to date, only little appropriate material is available especially for the Archaean. The Paleo- to Meso-Archaean Barberton Greenstone Belt, South Africa, represents the rosetta stone of research into the earliest Earth processes and conditions because it consists of little metamorphosed volcano-sedimentary successions. However, the primary (bio)geochemical signatures, especially of redox-sensitive elements, of outcrop samples may be compromised. Therefore, it is imperative to obtain continuous sections of unaltered, fresh material through drilling. Using drill core material from the Barberton Drilling Project, we seek funding to constrain (1) the metal sources, redox conditions and potential participation of biota in the Paleo-ocean, using Re-Os-Fe isotopes and platinum-group element systematics of organic-rich stratigraphic layers, banded iron formations and cherts deposited in the shallow to deep marine environment and (2) PGE and Os isotope composition of felsic volcanic rocks, which represent the continental sources of erosion products subsequently deposited on the ocean floor. Application of state-of-the-art geochemical tools to prospective sample material, strategic collaborations with other institutes and integration of data using multiple proxies offer a promising approach to successfully address these questions.