Evidence for Late Jurassic release of methane from gas hydrate

Four Late Jurassic carbonate successions deposited in the Tethys-Atlantic O cean record a negative carbon isotope excursion of at least 2 parts per tho usand. The excursion is present in both organic and carbonate carbon record s and is comparable in magnitude and duration to isotopic changes during th e late Paleocene thermal maximum. Our results indicate that during the Late Jurassic, long considered a warm greenhouse time, additional greenhouse ga s was input to the atmosphere by a sudden release of methane from buried ga s hydrate. A potential triggering mechanism may have been the opening of an oceanic gateway through the early Atlantic between the ancient Tethys and Pacific Oceans.