Abstract
Visible gas hydrate and possible pore-space hydrate samples have been recovered for the first time in North America from within ice-bonded permafrost in a 451-m-deep core hole in the Mackenzie Delta, Northwest Territories, Canada. The visible hydrate was found as thin icelike layers that released methane gas initially upon retrieval, but stabilized for up to 4 h at atmospheric pressure conditions and subfreezing temperatures. The temporary stabilization of hydrate samples is attributed to the self-preservation phenomenon described by others on the basis of laboratory studies. High methane concentrations in well-ice-bonded sediments and gas releases suggest that pore-space hydrate may be found at depths as shallow as 119 m. Geochemical and isotopic determinations suggest that the methane hydrate observed in the core hole is biogenic (microbial) in origin.
