Methane at the NW of Weddell Sea, Antarctica

Abstract

The presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane may suggest the presence of gas accumulations in the substrate of the NW Weddell Sea, Antarctica. The release of methane from the frozen ocean substrate adjacent to Seymour Island would be linked to climate instability during Late Cenozoic, when vast areas of the Antarctic continental shelf were flooded during the marine transgression that occurred c . 18,000 years ago, after the Last Glacial Maximum (LGM). As the ice melted, the sea again occupied the regions which it had abandoned. As the transgression was relatively rapid, the sub-air relief was not destroyed but was submerged and the ground had frozen (permafrost) along with it. Thus, the heat flow from the sea to the marine substrate, now flooded, would have destabilized frozen gas accumulations, which were originally formed into terrestrial permafrost during the LGM, similarly to what would have happened in the Arctic.