Methane hydrate dissociation across the Oligocene–Miocene boundary

Methane hydrate dissociation has long been considered as a mechanism for global carbon cycle perturbations, climate change and even mass extinctions in Earth’s history. However, direct evidence of hydrate destabilization and methane release coinciding with such events is scarce. Here we report the presence of diagnostic lipid biomarkers with depleted carbon isotopes from three sites in the Southern Ocean that are directly linked to methane release and subsequent oxidation across the Oligocene–Miocene boundary (23 million years ago). The biomarker evidence indicates that the hydrate destabilization was initiated during the peak of the Oligocene–Miocene boundary glaciation and sea-level low stand, consistent with our model results suggesting the decrease in hydrostatic pressure eroded the base of global methane hydrate stability zones. Aerobic oxidation of methane in seawater consumes oxygen and acidifies the ocean, acting as a negative feedback that perhaps facilitated the rapid and mysterious termination of glaciation in the early Miocene.

Kim B. & Zhang Y. G., in press. Methane hydrate dissociation across the Oligocene–Miocene boundary. Nature Geoscience. Article (subscription required).

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