Observations of gas hydrates in marine sediments, offshore northern California

摘要: Biogenic gas hydrates were recovered in shallow cores (< 6 m deep) from the Eel River basin offshore northern California between 40°38′ and 40°56′N. The contained primarily methane (δ13C = −57.6 to −69.1‰) occurred as dispersed crystals, small (2–20 mm) nodules, layered bands within sediment. These hydrates, sediment at water depths 510 642 m, coincide nearly, but not exactly, with areas showing bottom-simulating reflectors (BSRs) on seismic-reflection records. This study confirms indirect geophysical geologic observations that are present north of Mendocino Fracture Zone probably absent south Point Arena basin. discovery extends confirmed sites eastern Pacific region beyond Peruvian Central American margins margin.