Mercury evidence for pulsed volcanism during the end-Triassic mass extinction
Proceedings of the National Academy of Sciences
National Academy of Sciences
Reason for embargo
The Central Atlantic Magmatic Province (CAMP) has long been proposed as having a causal relationship with the end-Triassic extinction event (∼201.5 Ma). In North America and northern Africa, CAMP is preserved as multiple basaltic units interbedded with uppermost Triassic to lowermost Jurassic sediments. However, it has been unclear whether this apparent pulsing was a local feature, or if pulses in the intensity of CAMP volcanism characterized the emplacement of the province as a whole. Here, six geographically widespread Triassic–Jurassic records, representing varied paleoenvironments, are analyzed for mercury (Hg) concentrations and Hg/total organic carbon (Hg/TOC) ratios. Volcanism is a major source of mercury to the modern environment. Clear increases in Hg and Hg/TOC are observed at the end-Triassic extinction horizon, confirming that a volcanically induced global Hg cycle perturbation occurred at that time. The established correlation between the extinction horizon and lowest CAMP basalts allows this sedimentary Hg excursion to be stratigraphically tied to a specific flood basalt unit, strengthening the case for volcanic Hg as the driver of sedimentary Hg/TOC spikes. Additional Hg/TOC peaks are also documented between the extinction horizon and the Triassic–Jurassic boundary (separated by ∼200 ky), supporting pulsatory intensity of CAMP volcanism across the entire province and providing direct evidence for episodic volatile release during the initial stages of CAMP emplacement. Pulsatory volcanism, and associated perturbations in the ocean–atmosphere system, likely had profound implications for the rate and magnitude of the end-Triassic mass extinction and subsequent biotic recovery.
We acknowledge Natural Environment Research Council Grant NE/G01700X/1 (to T.A.M.) and PhD studentship NE/L501530/1 (to L.M.E.P.), Shell International Exploration and Production Inc., a Niels Stensen Foundation Research grant (to M.R.), the US National Science Foundation Grants EAR 0801138 and EAR 1349650 (to J.H.W.), and the Leverhulme Trust for funding.
This is the author accepted manuscript. The final version is available from National Academy of Sciences via the DOI in this record.
Vol. 114 (30), pp. 7929–7934