by Aivo Lepland, Mathieu Moussavou, Anthony R. Prave

The first half of the Paleoproterozoie Era (e. 2500 - 2000 Ma) is arguably one of the most extraordinary intervals in Earth history. lt ineludes the Great Oxidation Event (GOE) when Earth's surfaee environments and biosphere underwent a eomplete redox transformation to a planet rieh in free dioxygen (02). During the past two deeades the international Earth seienee eommunity has expended enormous researeh effort to understand the nature of this transformation, including the highly sueeessful ICDP-sponsored FAR-DEEP project in eastern Fennoseandia. Here we propose a Workshop !hat will build upon and eomplement all these previous efforts by signifieantly expanding knowledge about the Paleoproterozoie Earth system. We aim to obtain fresh drilleore from key stratigraphie inlervals in the Paleoproterozoie Franeevillian Basin of SE Gabon. The Franeevillian sueeession is unique beeause il has undergone minimal deformation and experieneed only minor thermal overprinting. Aequiring fresh eore of these well-preserved roeks will form an underpinning framework to integrale sedimentological, stratigraphie, geoehemieal and geoehronologieal datasets. This information will enable researehers to eonfidently reeonstruet original environmental eonditions and signifieantly reduee uneertainties surrounding geoehemieal proxy signals used to infer those eonditions. In effeet, the Franeevillian Basin holds the greatest promise of all Paleoproterozoie sueeessions to ereate the most reliable knowledge base to aseertain the genesis of the proeesses that led to emergenee of the modern aerobie Earth system.

• The project focuses on the fundamental questions about the development Earth's hydrosphere-atmosphere-biosphere system, the evolution of life and the associated environmental changes during Paleoproterozoic. These include: *What was the exact nature in the evolutionary trend of the Proterozoic oxygen, carbon, sulfur, phosphorous and nitrogen cycles; were they responding to global factors or to conditions bespoke to individual sedimentary basins? *What was the timing and tempo of the change in redox state of the ocean and atmosphere? *What are the individual and composite basinal trends in the isotopic and elemenlal ratio values of geochemical proxy records; how much influence do facies exert on those values? *How are these events correlated globally and what is their timing, rates and duration? *Are the U and Mn enrichments in Paleoproterozoic successions formed by oxidized fluids linked to the GOE or due to later diagenetic and/or fluid-rock interaction processes? *ls there independent evidence (e.g. biomarkers, microfossils) to assess the provocative idea that an exceptionally early metazoan biota evolved seemingly unique to the Franceville Basin? The proposed drilling project will form the core of an international, multidisciplinary initiative focusing on key stratigraphic intervals of the Francevillian succession. lt will obtain the necessary data to address the questions and unresolved problems posed above about Earth' s surface environments and their redox evolution during Paleoproterozoic time !hat can be used for creating a self-consistent model explaining the genesis and timing of the establishment of the modern Earth System.

Biochemical Cycles, Francevillian, Great Oxidation Event, Paleoproterozoic, Redox Proxies

Latitude: , Longitude: