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Invited research article

Mercury linked to Deccan Traps volcanism, climate change and the end-Cretaceous mass extinction

G. Keller, Mateo, P., Monkenbusch, J., Thibault, N., Punekar, J., Spangenberg, J. E., Abramovich, S., Ashckenazi-Polivoda, S., Schoene, B., Eddy, M. P., Samperton, K. M., Khadri, S. F. R., and Adatte, T.



  • Hg anomalies in sediments are a reliable proxy for Deccan volcanism
  • Deccan eruptions caused long-term climate warming in the last 350 ky of the Cretaceous
  • Long-term climate warming resulted in faunal decline but no extinctions
  • Paroxysmal Deccan eruptions occurred during the last 25 ky of the Cretaceous
  • Deccan-induced hyperthermal and ocean acidification led to the KPB mass extinction

Mercury (Hg) anomalies linked to Large Igneous Provinces (LIP) volcanism have been identified in sediments across all five major mass extinctions in Earth's history. This study tests whether Hg in marine sediments is a reliable proxy linking Deccan Traps volcanic eruptions to late Maastrichtian global climate warming and the mass extinction at the Cretaceous-Paleogene boundary (KPB). Our primary test site is the Elles section in Tunisia, the auxiliary Global Stratotype Section and Point (GSSP) to El Kef. Elles has the most complete marine sedimentary record and a high average sedimentation rate of ~4.7 cm/ky. We chose the Hor Hahar section in Israel to corroborate the geographic distribution of Hg fallout from Deccan volcanism. Reliability of the Hg proxy over the last 550 ky of the Maastrichtian to early Danian was evaluated based on high-resolution age control (orbital cyclostratigraphy), stable isotope climate record, Hg concentrations, biotic turnover and mass extinction. These results were correlated with the pulsed Deccan eruptive history constrained previously by U-Pb zircon geochronology.

Our results support Hg as robust proxy for Deccan volcanism with large Hg spikes marking “extreme event” (EE) pulsed eruptions correlative with climate warming peaks separated by steady, less intense eruptions. Longterm global climate warming began near ~350 ky pre-KPB, reached maximum warming (3–4 °C) between 285 and 200 ky pre-KPB, followed by gradual cooling and rapid temperature drop between 45 and 25 ky pre-KPB. During the last 25 ky before the KPB, multiple Hg EE eruptions correlate with hyperthermal warming that culminated in the rapid mass extinction at Elles during ≤1000 years of the Cretaceous. These latest Cretaceous Hg peaks may correlate with massive, distal, Deccan-sourced lava flows (> 1000 km long) that traversed the Indian subcontinent and flowed into the Bay of Bengal, bracketing the mass extinction. These results support Deccan volcanism as a primary driver of the end-Cretaceous mass extinction.  PDF

Fig. 2 The mass extinction, climate change, Mercury fallout directly correlated to cataclysmic Deccan eruptions. (see full Fig. captions below)Fig. 2. Fig. 7. High-resolution planktic foraminifera and relative abundances, δ18O and Hg data at the astronomically tuned Elles section in Tunisia and comparison with δ18O data at Sites 525A and 1262, Deccan Traps stratigraphy and geochronology. Note the direct link between Hg anomalies and δ18O at Elles (and at Sites 525A and 1262, except for the KPB hiatus) demonstrates the effect of Deccan volcanism on global climate; the rapid increase in Hg loading (paroxysmal Deccan eruptions) correlates to hyperthermal warming and surface ocean acidification during the last 25 ky pre-KPB. Ocean acidification is also observed in C30n, lower C29n (CF2 and CF2/CF1). Increased stress on marine life through the late Maastrichtian (increased relative abundance of disaster opportunist species, decreased specialist species) reached maximum during the last 25 ky pre-KPB and ended with the mass extinction. KPB age at 66.016 Ma; Deccan Traps U-Pb dates from Schoene et al. (2015, 2019) and Eddy et al. (2020). Uncertainty in cyclostratigraphic ages: 20 ky (one precession cycle). Ma: millions of years ago, ky: thousands of years.