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
Constraining Carbon flux from the Central Atlantic Magmatic Province- insights from metasediments from Florida
Paper number: 67-2
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM
Authors
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Lindsi Allman Presenting AuthorFlorida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, Florida
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Emily StewartFlorida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, FL
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Kanwa SenguptaFlorida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, FL
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Mainak MookherjeeFlorida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, FL
Abstract
The emplacement of Large Igneous Provinces (LIPs) and associated rapid release of carbon to the surface is often linked with catastrophic climatic changes, possibly leading to mass extinctions. Most of the released carbon is often associated with volcanic emissions; however, high-grade contact metamorphism of sediments by intruding dikes and sills may release up to 100% of the trapped sedimentary carbon from host rocks. While numerical modeling has provided crucial insights into the outward flux of metamorphic carbon, ground truthing from field-based observation is often lacking and is much needed for validation.
To provide such field-based constraints on outward carbon flux, we examine sediments metamorphosed by basaltic sills associated with the Central Atlantic Magmatic Province (CAMP), captured in two boreholes from the Florida basement. We use geochemical and textural analysis, and thermodynamic modeling to constrain carbon release. In addition, we performed 1-D thermal modeling and estimated temperatures using vitrinite reflectance of sedimentary organic matter and complementary Raman Spectroscopy to assess thermal maturity.
Our results indicate that carbon in the form of CO2 was released from carbonates below a 10 m sill. This is accompanied by upward fluid transport and some recapture of CO2 at the top of the sill. While CO2 from carbonate is mobilized, evidence suggests minimal movement of organic carbon, likely due to the high activity of CO2 during heating. We estimate ~0.0- 7.1 x 103 moles C m-2 released. This large range is primarily the result of uncertainties in the volumetric extent of carbonation. Our estimated upper bound agrees well with prior modeled estimates from other regional CAMP studies. Additionally, we noted a discrepancy between the apparent temperature predicted using Raman Spectroscopy of Carbonaceous Material (RSCM) and the predicted peak temperatures from 1D thermal modeling. Although limitations of RSCM temperature calibrations and/or simplifications in 1-D thermal modeling may cause such a discrepancy, the observed deviation of ~100 °C would not be expected. A likely explanation for such temperature discrepancy is the presence of aqueous pore fluid in the sediment below the sill, and short heating timescales may account for such a mismatch. Our study demonstrates that a combination of field-based study, geochemical & spectroscopic analysis, and heat flow modeling is crucial for gaining insights into the mobility of carbon during LIP emplacement.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-413794
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