Over 4.5 billion years, Earth has evolved from a molten ball to a cooler planet with large continental plates, but how and when continents grew and plate tectonics started remain poorly understood. In this paper, I review the evidence that 3.5 Ga continental nuclei in Australia formed as thick volcanic plateaux over hot, upwelling mantle and survived due to contemporaneous development of a thick, buoyant, unsubductable mantle root. This type of crust is distinct from, but complimentary to, high-grade gneiss terranes that formed through arc-accretion tectonics on what is envisaged as a vigorously convecting early Earth with small plates. Thus, it is proposed that two types of crust formed on early Earth, in much the same way as in modern Earth, but with distinct differences resulting from a hotter Archean mantle. A remaining question of how plate tectonics was initiated on Earth is investigated, using an analogy with Artemis Corona on Venus.
- Continental Crust
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)