Glacial Methane Hydrate Dissociation in the South China Sea Margin During the Oligocene

Methane hydrate dissociation along continental margins has been widely associated with global carbon cycle perturbations and climate changes. However, the relationship between hydrate dynamics, carbon cycle disturbances, and climate variations remains unclear. Here, we report eleven anomalously depleted carbon isotope excursions in benthic foraminifera, along with increased coccolith recrystallization, suggesting episodic methane release from the northern South China Sea during the Oligocene. These abnormal patterns were generally coupled with benthic oxygen isotope maxima, indicating that hydrate destabilization was triggered by ice sheet expansion and sea-level decline during the Antarctic glaciations. This contrasts with the majority of previous studies, which have typically linked methane-sourced carbon emissions to global warming throughout Earth's history.