Climate-forced Hg-remobilization driving mutagenesis in ferns in the aftermath of the end-Triassic extinction

The long-term effects of the Central Atlantic Magmatic Province (CAMP), a large igneous province connected to the end-Triassic mass-extinction (201.5 Ma), remain largely elusive. Here, we document the persistence of volcanic-induced mercury pollution and its effects on the biosphere for 2 million years after the extinction event. In sediments recovered in Germany (Schandelah-1 core), we record not only high abundances of malformed fern spores at the Triassic-Jurassic boundary, but also during the Hettangian, indicating repeated vegetation disturbance and environmental stress that was eccentricity forced. Crucially, these abundances correspond to spikes in sedimentary Hg concentrations. Hg-isotope ratios (δ 202 Hg, Δ 199 Hg) indicate a volcanic source at the Triassic-Jurassic boundary but a terrestrial source for the early Jurassic peaks. We conclude that Hg injected by CAMP across the extinction was repeatedly remobilized from coastal wetlands and hinterland areas during eccentricity-forced phases of severe hydrological upheaval and erosion, focusing Hg-pollution in shallow marine basins.