T331 Mercury in the Geologic Record

Wednesday, 25 October 2017
1:30 PM - 5:30 PM
Room 607

MERCURY CONCENTRATIONS AND MERCURY STABLE ISOTOPE VARIATIONS AT THE PETM: VOLCANIC LOADING SIGNAL OF THE NORTH ATLANTIC IGNEOUS PROVINCE?

Paper number: T331-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) represents one of the most abrupt (~2 kyr onset; < 220 kyr duration), large-magnitude (~5 to 8 °C; global average) warming events of the Cenozoic. Associated with the PETM are extensive benthic marine extinctions, with significant ramifications for terrestrial biomes globally. A proposed mechanism for the initiation of the PETM is climate forcing from volcanogenic volatile emissions (principally CO2) produced by North Atlantic Igneous Province (NAIP) flood basalts, and a subsequent positive feedback response involving destabilization of shallow seafloor clathrates (gas hydrates, principally CH4). Here, we present a record of total Hg [THg] concentrations of ocean sediments from three localities ranging from the Arctic Ocean to the South Atlantic. We observe a record of elevated [THg] coincident with well-documented carbon isotope (δ13C) excursions in the same marine sediment cores at Walvis Ridge (South Atlantic), Bass River (New Jersey), and Svalbard (Norway), where measured maximum [THg] at each site ranged from 0 to 16.2, 12.6 to 31.5, and 5.2 to 91 ng/g, respectively. Elevated [THg] at each of these localities may be the result of increased volcanogenic Hg emissions from the NAIP. Volcanic emissions of gaseous elemental mercury (Hg0), thought to be the largest time-averaged source of Hg to the atmosphere, represent a small fraction of total volatiles released from eruptions of the NAIP, and would occur in conjunction with CO2 and other gases responsible for climate forcing. We also document a large magnitude (≥ 3‰) δ202Hg excursion across the PETM at Walvis Ridge, coincident with peak [THg] values. Further investigation of stable Hg isotopic variations at each site is ongoing, and will help further constrain the mechanism(s) behind rapid PETM warming.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-296370

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