67 Long- and Short-Term Environmental Consequences of Large Igneous Provinces Throughout Earth’s History (Posters)

We invite submissions to an interdisciplinary session on Large Igneous Provinces (LIPs), exploring their environmental impacts using geochronology, paleomagnetism, geochemistry, paleoenvironmental proxies, and modeling to integrate diverse data into understanding LIP-induced environmental changes.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Biogeochemical Dynamics Triggered by Large Igneous Province Eruptions in the Mesoproterozoic: A Modeling Perspective

Paper number: 67-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Understanding the stability of the redox state of Earth’s ocean-atmosphere system is crucial for unraveling the co-evolution of Earth’s environment and biosphere. The Mesoproterozoic Era has traditionally been viewed as a period of environmental and evolutionary stasis. However, emerging geochemical evidence—including redox-sensitive trace elements, Cr isotope anomalies, carbonate I/(Ca+Mg) ratios, and Ce anomalies—indicates that transient oxygenation events occurred at least three times between 1.6 and 1.4 Ga. These events were likely accompanied by enhanced continental weathering, ocean eutrophication, and carbon and sulfur isotope anomalies, suggesting global environmental perturbations. While the ultimate drivers of these transient oxygenation events remain uncertain, the detection of Hg enrichments and isotope anomalies beneath the relevant stratigraphic horizons suggests a causal link with large-scale magmatic activity associated with the emplacement of Large Igneous Provinces (LIPs). However, it remains unclear whether the observed geochemical records can be quantitatively explained as biogeochemical responses to such magmatism.

To investigate this, we conducted numerical experiments using the CANOPS model, which simulates biogeochemical cycles of C, N, P, O, and S across the ocean, atmosphere, and lithosphere. The model was initialized with the Mesoproterozoic Earth system conditions (atmospheric O2 ≈ 2% of present atmospheric level (PAL), CO2 ≈ ~100 x PAL, ocean P ≈ 10% modern level, and global mean surface temperature at 290K). Volcanic degassing scenarios simulating Phanerozoic LIP formation were applied, incorporating emissions of CO2 and reduced gases.

The typical simulation demonstrates that LIP-induced warming (+10 K) enhances continental weathering, increasing nutrient input and leading to ocean eutrophication (oceanic P ≈ 60% modern levels). This initially results in ocean deoxygenation. However, enhanced burial of organic carbon and pyrite eventually drives a rise in atmospheric O2 (~16% PAL) within 500 kyr, leading to a more oxidizing ocean state. Simultaneously, oxidative weathering of terrestrial organic matter and the release of isotopically light CO2 from LIPs produce negative δ13C anomalies (−1 to −2 permil), despite elevated primary productivity. The δ34S values exhibit a large positive shift (+50 permil), reflecting euxinia expansion and increased pyrite burial.

These results align with geochemical observations and support the hypothesis that Mesoproterozoic transient oxygenation events were triggered by LIP events. Our model also predicts early-stage warming and ocean deoxygenation, warranting further geological and geochemical validation.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412850

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