Mercury Chemostratigraphy and Geochemical Box Model Constraints on Large Igneous Province Eruption Rates: Case Studies from the Deccan and Siberian Traps
Abstract
Large Igneous Provinces (LIPs) impact climate through the release of CO2 and SO2. The climate effects of these volatiles, particularly SO2, are highly dependent on the rate of emission, and thus high-resolution LIP eruptive fluxes can predict potential climate impacts - assuming eruptive degassing is the primary form of volatile release. While main-phase LIP emplacement lasts ~ 1 million years, active eruptions may occur only 1% of the time, and the tempo of individual eruptive episodes is uncertain. Mercury chemostratigraphy is one way to constrain the timing of LIP eruptions, and there are now mercury concentration records for many periods in geologic history.
Mercury gas emitted by large igneous province eruptions is hypothesized to significantly increase the global mercury budget for the duration of each eruption. In the case of the Siberian Traps, this also includes mercury released by heating of sediments by intrusive magmas. This increase should be apparent in sedimentary records from diverse environments. However, to compare mercury records from different locations and depositional environments, one must account for differences in sedimentation rate, sampling resolution, and sedimentary conditions such as organic carbon and sulfur concentration. We have developed a new statistical framework which uses environmental mercury cycle box models to estimate eruptive rates and volumes by quantitatively evaluating the changes in global mercury budget indicated by varying concentrations in sedimentary records. We then create synthetic mercury records for a variety of potential eruptive histories and statistically compare the synthetic records with actual sedimentary records. We utilize this framework to compare mercury chemostratigraphic records from the literature for both the Cretaceous-Paleogene and Permian-Triassic intervals, as well as a new high-resolution Cretaceous-Paleogene record from Montana. These records constrain Deccan Traps and Siberian Traps eruptive tempo and flux, allowing direct comparison between hypothesized climate effects and actual paleoclimate records.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V31C0116F
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY;
- 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICS;
- 8408 Volcano/climate interactions;
- VOLCANOLOGY