Abstract
Exceptional magmatic events coincided with the largest mass extinctions throughout Earth's history. Extensive degassing from organic-rich sediments intruded by magmas is a possible driver of the catastrophic environmental changes, which triggered the biotic crises. One of Earth's largest magmatic events is represented by the Central Atlantic Magmatic Province, which was synchronous with the end-Triassic mass extinction. Here, we show direct evidence for the presence in basaltic magmas of methane, generated or remobilized from the host sedimentary sequence during the emplacement of this Large Igneous Province. Abundant methane-rich fluid inclusions were entrapped within quartz at the end of magmatic crystallization in voluminous (about 1.0 × 10(6) km(3)) intrusions in Brazilian Amazonia, indicating a massive (about 7.2 × 10(3) Gt) fluxing of methane. These micrometre-sized imperfections in quartz crystals attest an extensive release of methane from magma-sediment interaction, which likely contributed to the global climate changes responsible for the end-Triassic mass extinction.