Enhanced erosion by continental arc volcanism as a driver of the Cambrian Explosion.

Abstract

Nutrient availability and rising oxygen levels are important for the Cambrian Explosion (~540-515 Ma), both of which can be satisfied via enhanced weathering driven by climate and tectonics. Although increased subduction and continental arc volcanism coincided with the Cambrian Explosion, their weathering-nutrient feedback role remained unclear. Here we integrate Li-Os isotopes with previously published Sr isotope to investigate connections between subduction-driven weathering dynamics and animal diversification. Our results reveal a shift from enhanced erosion of arc-related juvenile rocks (ca. 540-525 Ma) to clay-forming weathering of old crust (525-515 Ma). We propose that subduction-driven warming and uplift may have accelerated erosion of phosphorus-rich juvenile rocks, releasing nutrients that boosted marine productivity and subsequent oxygen buildup through organic burial. This process ultimately fueled early animal diversification, providing additional evidence for tectonic control of biogeochemical cycles during the Cambrian Explosion.