Séminaire ISTerre

MasterClass #5 : Débat sur le début de la tectonique des plaques et l’émergence des continents par Nick Arndt

mardi 28 juin 2022 - 09h00
Nick Arndt, Bruno Dhuime, Marion Garçon, Peter Cawood - ISTerre, Universté de Montpellier, Université Clermont Auvergne, Monash University
--- 
Matinée du 28 juin 2022 dédiée à Nick Arndt : Débat sur le début de la tectonique des plaques et l’émergence des continents .

8h40 - 9h00 Coffee

9h00 - 9h15 Introductory words (Ph. Roux, Director) and presentation of the program (C. Cordier, Chair)

9h15 – 10h00 Nick Arndt will start by presenting the main issues and questions :
- When did plate tectonics start ?
- The rate of growth of continental crust through geological time
- The tempo of growth of continental crust – continuous or episodic ?
- The mechanism of crustal growth – subduction- or plume-related ?
- When did subduction become the main granite-forming process ?
- Composition and thickness of Archean continental crust ?
- Temperature and style of convection of the Archean mantle ?

He will then give his view on these issues, explaining that he advocates an early start of subduction, entertains the idea of early plate tectonics, and promotes mantle-pulse-driven episodic growth of the continental crust.

10h00 - 10h30 Bruno Dhuime, University Montpellier, will then argue that plate tectonics started no earlier than 3 Ga preceded by a stagnant lid tectonic regime, that the continental crust formed continuously, interrupted by periods of enhanced recycling, and that the composition and thickness of the continental crust was different in the Archean.

10h30 - 10h45 Marion Garçon, University Clermont Auvergne, will summarise recent results based on the geochemistry of sedimentary rocks to support the idea of early episodic continental growth.

10h45 - 11h00 Peter Cawood, Monash University, Melbourne, will review some of the key arguments and how we might take this discussion forward.

11h00 – 12h00 Open discussion (C. Cordier, Chair)

Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/91446159474?pwd=S04vT0tRZjVScldyODlxNGpaYURwQT09