Sulfur in olivine-hosted melt inclusions from the Emeishan picrites: Implications for S degassing and its impact on environment

Large-volume (>0.3x10(6) km(3)) basaltic lavas that erupted similar to 260 Ma ago in southwest China form the Emeishan large igneous province. The relationship between the Emeishan volcanism and the end-Guadalupian mass extinction is still unresolved. In order to evaluate the impact of Emeishan flood volcanism on the climate and environment, we have measured sulfur contents in olivine-hosted melt inclusions from Dali picrites. The highest S content of melt inclusions is up to 1311 ppm, which represents that of the undegassed magmas. Comparing the S contents in the undegassed magma and in the degassed posteruptive basaltic lavas, we calculate that eruptions of the Emeishan lavas could have released at least similar to 900 ppm of S, which equates to 5 Mt of SO2 per cubic kilometer of basaltic lavas. During an individual eruption, SO2 could have been added to the atmosphere at a rate of 1.5x10(2)-10(3) Mt/yr, creating 3.1x10(2)-10(3) Mt of H2SO4 aerosols. The quick release of such a huge amount of volatiles into the atmosphere may have absorbed and reflected solar radiation, causing a temperature decrease and eventually leading to a volcanic winter. This scenario demonstrates that the Emeishan flood volcanism was responsible for the end-Guadalupian mass extinction.