At the Dawn of Continents: Archean Tonalite-Trondhjemite-Granodiorite Suites

• DOI: 10.2138/gselements.20.3.174
• Publication Date: 2024-06-03T15:54:12Z
• Authors: Oscar Laurent; Martin Guitreau; Emilie Bruand; Jean-François Moyen
• Keywords: Silicic

Archean rocks of the tonalite-trondhjemite-granodiorite (TTG) suite are dominant constituents Earth’s earliest preserved silicic crust, while conversely rare in Phanerozoic continental crust. Their formation represents first critical step towards construction and preservation continents. Formation most TTG magmas involved partial melting hydrous, probably silicified, mafic at various depths (20–50 km, possibly up to 100 km). Many possible tectonic scenarios fit petrological geochemical constraints on formation, whether compatible with a global plate tectonic-like regime or not. Refining such is major challenge that requires systematically integrating formation—relying especially accessory minerals as key petrogenetic tools—with geological context regional scale.