Dear colleagues, Please consider the following session 3d at Goldschmidt Conference Lyon 2021 (4-9 July 2021). Abstract submission deadline and Student Helper application deadline 26 February 2021 Theme 3: Earth's Lithosphere through Time: from Hadean to Modern Session Number 3d Title The Earth in Transition: from pre-Plate Tectonics to Plate Tectonics. How and when did global Plate Tectonics begin on Earth and what went before? We welcome contributions on geochemical and petrological constraints and geodynamic models focused at global recycling on Earth, at styles of global tectonics and their temporal evolution, the origin and relation of subduction to Archean crustal and mantle-derived rocks, and the Hadean/Archean record from refractory minerals such as zircon, olivine, chromite and diamond. Conveners Stephan V Sobolev  <https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Person/17664> GFZ Potsdam John W. Valley  <https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Person/19072> Dept of Geoscience, U. Wisconsin Alexander V Sobolev  <https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Person/159> University Grenoble Alps https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Session/1915 <https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Session/1915> ________________________________________ Professor Alexander Sobolev Institut des Sciences de la Terre (ISTerre) Université Grenoble Alpes-CNRS Maison des Géosciences 1381 rue de la Piscine BP 53, 38041 Grenoble Cedex 9, France Tel: 33 (0)476514108 Fax: 33 (0)476635252 E-mail: alexander.sobolev@univ-grenoble-alpes.fr http://scholar.google.ru/citations?user=4IR9u1QAAAAJ&hl=en&oi=ao