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Article Dans Une Revue Palaeogeography, Palaeoclimatology, Palaeoecology Année : 2016

Geochemical consequences of intense pulse-like degassing during the onset of the Central Atlantic Magmatic Province

Résumé

The Triassic–Jurassic boundary (TJB) ismarked by one of the five largestmass extinctions of the Phanerozoic and the eruption of a large igneous province: the Central AtlanticMagmatic Province (CAMP). The TJB is characterized by a carbonate production crisis, by negative excursions in the carbon isotopic ratio of buried organic matter, and by successive peaks in atmospheric CO2. Herewe use the numerical model GEOCLIMto explore the possible connections between the CAMP emplacement and the observed carbon cycle perturbations. Different degassing scenarios linked to the CAMP eruption are explored. We show that the emission of realistic amounts of CO2 that follow a geologically constrained degassing scenario as short-termpeaks (less than 10 ka) leads to successive decrease in carbonate production, as observed in the geological record. We also calculate the evolution of carbon isotopes and show that our model reproduces the amplitude of the isotopic excursion with a volcanic degassing of CO2 characterized by a carbon isotopic composition of −20‰. Such low values could be associated to carbon pools of light isotopic composition located at the transition zone [Cartigny, P. 2010, Earth and Planetary Science Letters, v. 296, p. 329–339] and not necessarily to biogenicmethane release. Finally, themodel predicts a succession of short-term CO2 rises, with an amplitude in close agreement with available proxy-based reconstructions.
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hal-01258976 , version 1 (19-01-2016)

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Guillaume Paris, Yannick Donnadieu, Valérie Beaumont, Frédéric Fluteau, Yves Goddéris. Geochemical consequences of intense pulse-like degassing during the onset of the Central Atlantic Magmatic Province. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016, 441, pp.74-82. ⟨10.1016/j.palaeo.2015.04.011⟩. ⟨hal-01258976⟩
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