by Aivo Lepland, Kalle Kirsimäe, Mathieu Moussavou, Anthony R. Prave

Oxygenation of the atmosphere and upper layers of the oceans and evolution of aerobic microbial ecosystems during Proterozoic time are amongst the most profound events in Earth history. The international Earth science community has striven for years to understand these events, often through large multidisciplinary research initiatives such as the highly successful ICDP-sponsored FAR-DEEP project in eastern Fennoscandia. Our new multinational, multidisciplinary initiative GOE-DEEP aims to significantly expand understanding of Paleoproterozoic Earth history by obtaining 11 fresh drill cores from the Franceville Basin of Gabon, likely the best-preserved archive of Paleoproterozoic sedimentary rocks globally. Drill cores from those rocks will form a new sedimentological, paleontological, geochronological and geochemical knowledge base. Such data will reduce significantly existing uncertainties about the genesis of geochemical proxy signals and help reconstruct original environmental conditions across this critical time of Earth’s past. The multi-hole strategy involves drilling cores that recover laterally correlative paleoenvironmental transects from shallower to deeper portions of the same stratigraphic interval across different depositional settings (i.e. from the shoreline to the shelf to the slope-basin plain). This is the only way to confidently determine if geochemical signals are recording facies-specific conditions or if signals are basin-wide hence of potential global significance. GOE-DEEP maps directly onto ICDP´s key scientific themes of (i) geodynamic processes, (ii) geo-resources, (iii) environmental change and life evolution, and could also contribute understanding of (iv) geohazards through documentation of the potential widespread effect of ancient meteorite impacts. Thus, the Franceville Basin offers great promise to resolve fundamental questions about the emergence of Earth´s aerobic biosphere-hydrosphere-atmosphere system. The collective expertise of the GOE-DEEP team, combined with access to state-of-the-art facilities, gives confidence to ensure attaining the scope of data necessary to achieve the drilling and scientific goals embodied in the GOE-DEEP initiative, as well as clearly communicating and sharing these critical findings with the public. GOE-DEEP scientists, through the project’s outreach and training educational programs, will work closely with Gabonese and partner universitie

• The objectives of GOE-DEEP are to provide insights into and answers to fundamental questions about the development of Earth´s hydrosphere-atmosphere-biosphere system, the evolution of life, and the associated environmental changes during early Paleoproterozoic time. These include:
• What controlled Proterozoic oxygen, carbon, sulfur, phosphorus 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 oceans and atmosphere?
• What are the individual and composite basin trends in the isotopic and element-ratio values of geochemical proxy records, and how much influence do facies exert on those values?
• Are events globally synchronous or diachronous, and what was their timing and duration?
• Were Paleoproterozoic environmental conditions affected by meteorite impacts?
• Is there independent evidence (e.g. microfossils, organic geochemistry indicators) to assess the provocative idea that an early, unique metazoan biota, or any other form of eukaryotic life, evolved in the Franceville Basin?
• Are U and Mn enrichments in Paleoproterozoic successions formed by oxidized fluids linked to the GOE or due to later diagenetic overprints and hydrothermal processes?

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

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