Holocene Methane Emissions in the Southwestern Sea of Okhotsk: Evidence from Carbon Isotopes in Benthic Foraminifera Shells

Several negative stable carbon isotope excursions are revealed in benthic foraminifera from the LV50-05 gas-bearing core collected from an area of active methane venting on the eastern slope of Sakhalin Island, Sea of Okhotsk. Within the study area, four methane events (ME) were established to have taken place during the Holocene, short-term ones—ME-1 (700–900 yrs BP) and ME-2 (1200–1400 yrs BP)—and long-term ones—ME-3 (2500–5400 yrs BP) and ME-4 (7400–10 000 yrs BP).