During the latest Eocene, as Earth's climate transitioned from a greenhouse to an icehouse state, likely forced by declining atmospheric carbon dioxide pressure (pCO2), a large tract of basic and ultrabasic seafloor breached sea level in the New Caledonian region of the southwestern Pacific Ocean. A plausible mechanism for CO2 drawdown at this precise time, 35–34 Ma, invokes weathering of the seafloor rocks, composed of highly soluble Ca- and Mg-rich silicates, and related organic carbon burial. Carbon burial fluxes based on estimates of paleo-area, paleo–erosion rate, and paleo–sedimentation rate suggest a peak perturbation of 0.3–0.5 Emol (1018 mol) m.y.−1 This perturbation may have been sufficient to lower atmospheric pCO2 ∼100 ppmv, thus triggering growth of the East Antarctic ice sheet and a host of related environmental changes.

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