Volcanic phosphorus spikes associated with supercontinent assembly supported the evolution of land plants

Abstract

The origin and evolution of land plants in the Ordovician and Carboniferous reshaped the terrestrial environment, marine ecology, and atmospheric composition, ultimately triggering global climate change. Phosphorus (P) is a limiting nutrient for plants and can only be obtained from pedogenic weathering of bedrock (including rocks and deposits). In the Ordovician and Carboniferous, periodic and frequent volcanic eruptions at convergent plate margins formed the bedrock that elevated P supply for the terrestrial biosphere. Temporal variation of P availability reveals that volcanic P supply spiked at 474–465 Ma, 454–445 Ma, and 319–310 Ma, with the assembly of Gondwana and Pangaea supercontinents. The abundant P supported the crucial Phanerozoic ecological transitions marked by the episodically increased land plant biomass and emergence of non-vascular, vascular, and seed plants. The volcanism-driven evolution and expansion of land plants further accelerated rock weathering and enhanced organic carbon burial. This positive feedback eventually resulted in the ice ages in the Paleozoic. Therefore, the variation of P availability, dependent on the scale and P content of volcanic products, was strongly associated with the plate subduction during supercontinent assembly, revealing the significant impact of tectonism on terrestrial ecosystems.