Titanium isotopic evidence for felsic crust and plate tectonics 3.5 billion years ago

• DOI: 10.1126/science.aan8086
• Publication Date: 2017-09-21T18:11:19Z
• Authors: Nicolas D. Greber; Nicolas Dauphas; Andrey Bekker; Matouš P. Ptáček; Ilya N. Bindeman; Axel Hofmann
• Keywords: Felsic; Billion years

Earth exhibits a dichotomy in elevation and chemical composition between the continents ocean floor. Reconstructing when this arose is important for understanding plate tectonics started how supply of nutrients to oceans changed through time. We measured titanium isotopic shales constrain continental crust exposed weathering found that all ages have uniform composition. This can only be explained if emerged was predominantly felsic (silica-rich) since 3.5 billion years ago, requiring an early initiation tectonics. also observed change abundance biologically phosphorus nickel across Archean-Proterozoic boundary, which might helped trigger rise atmospheric oxygen.