PETM onset triggered by intense volcanism in the North Atlantic: evidence from tellurium

The Paleocene – Eocene Thermal Maximum (PETM) was a global hyperthermal event during which temperatures increased by 6 - 8° C within a few thousand years at the Paleocene - Eocene boundary, and lasted about 250 ka resulting in ocean acidification, anoxia, and marine extinctions. The PETM coincided with the opening of the North Atlantic and the emplacement of the North Atlantic Igneous Province (NAIP). However, because of the short duration of the PETM compared to NAIP volcanism (several Ma), the contribution of NAIP volcanism to these environmental changes is unclear.

Previous studies have used mercury (Hg) enrichments in Paleocene - Eocene sediments as a proxy to link the timing and intensity of NAIP volcanism to the environmental changes at the PETM. However, published Hg and Hg/TOC profiles across the PETM from various locations are different, indicating that Hg is affected by processes other than volcanism. Here we use tellurium (Te), a volatile trace element that is highly enriched in volcanic gas relative to crustal rocks, as an alternative proxy for NAIP volcanism. Te and other trace element concentrations were measured by ICP-MS in sediments from the Fur Formation in Denmark and DSDP Site 550 in the North Atlantic, which span the PETM. Sediments of both study sites are enriched in Te with averages between 200 to 300 ppb and thus exceeding estimated average crustal concentrations of 1 – 5 ppb drastically. In both locations, Te and Te/Nb ratios increase abruptly at the level of the carbon isotope excursion (CIE) onset, remain high during the PETM ‘body’, and decrease towards the end of the main North Atlantic ash phase. The Te variations are not correlated with trace element proxies for anoxia or productivity. The Te data support recent Hg isotope data indicating a brief intense phase of NAIP volcanism initiating at the onset of the δ¹³C excursion and lasting for a few 100 ka. The coincidence of the main volcanic pulse and the CIE onset suggests that the source of the light carbon may be volcanic, rather than metamorphic.