Overview

• New research suggests that the first continents were formed before the start of plate tectonics, and were made up of three types of coarse-grained rocks, collectively called granitoids.
• The process of formation of the first crust has puzzled geologists, particularly regarding the involvement of plate tectonics.
• The original crust was composed of three types of rock; tonalite, trondhjemite, and granodiorite, collectively known as TTG.
• Researchers analyzed materials collected worldwide to find the commonalities and ignore the rest.
• The study dispels the long-standing theory that Archean TTGs are formed in Earth's first subduction zones and mark the start of plate tectonics.