Distribution and height of methane bubble plumes on the Cascadia Margin characterized by acoustic imaging

摘要: Submersible investigations of the Cascadia accretionary complex have identified localized venting methane gas bubbles in association with hydrate occurrence. Acoustic profiles these bubble plumes water column vicinity Hydrate Ridge offshore Oregon provide new constraints on spatial distribution vents and fate column. The vent sites remained active over span two years, but varied dramatically time scales a few hours. All emanated from local topographic highs near summit ridge structures. acoustic images disappear at depths between 500 to 460 m, independent seafloor depth. This coincides predicted depth stability boundary 510 490 suggesting that presence skin surface prevents them rapid dissolution. upper limit m suggests dissolution residual is relatively above zone.