Peraluminous igneous rocks as an indicator of thermogenic methane release from the North Atlantic Volcanic Province at the time of the Paleocene–Eocene Thermal Maximum (PETM)
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Unusual cordierite-bearing peraluminous dacites, produced by melting of organic-rich sediments by intrusion of basaltic magma, are found within the North Atlantic Volcanic Province (NAVP). Calculations suggest that formation of the dacites, radiometric dated at 55.9 ± 0.3 Ma and possibly widespread, could have released an average of ∼4,500 Gt (range from 3,000 to 6,000 Gt) of carbon as methane, with a δ13C of about −35‰. Published model results suggest that such a methane release could explain the negative δ13C excursion in the oceans and atmosphere, the extreme global warming, and the marked dissolution of carbonates in the deep oceans that accompanied the concurrent Paleocene–Eocene Thermal Maximum (PETM). Outgassing from melting of sediments and formation of dacites, possibly in conjunction with methane produced in contact metamorphic aureoles and by methane hydrate release, provides a novel way of explaining the PETM and its timing.
KeywordsNorth Atlantic Volcanic Province Paleocene–Eocene Thermal Maximum Peraluminous dacites
Thanks to S. Self, Th. Thordarson, H. Svensen, A. Miles, and S. Galeotti for careful reading of the paper.
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