Modern-style arc magmatism since ca. 2.2 billion years ago revealed by Nb/Ta-Dy/Yb systematics in igneous rocks

Abstract

The subduction of oceanic lithosphere is a significant mechanism in plate tectonics, which regulates volcanic activity along convergent plate boundaries on the modern Earth. However, while there is evidence for at least episodic, hot subduction in the Archaean, modern-style subduction might have not occurred on the early Earth under a different tectonic regime, potentially due to the high mantle temperature. It remains uncertain when modern-style subduction and its corresponding arc magmatism started operating on a global scale. Here we show that the modern arc intermediate-felsic rocks exhibit a distinct Nb/Ta-Dy/Yb correlation compared to their Archean counterparts due to the contrasting petrogenesis. Our statistical analysis of a worldwide igneous rock database, spanning geological history, indicates the widespread occurrence of intermediate-felsic rocks with modern arc signatures since ca. 2.2 Ga, which coincides with the onset of the supercontinent cycle. Continuous subduction of the cold oceanic lithosphere not only gave rise to arc magmatism along active margins but also accelerated the cooling rate of the mantle, which largely terminated the widespread formations of intermediate-felsic rocks derived from crustal delamination and slab melting.