https://dx.doi.org/10.1029/2004GL021286">
 

Abstract

Log and core data document gas saturations as high as 90% in a coarse‐grained turbidite sequence beneath the gas hydrate stability zone (GHSZ) at south Hydrate Ridge, in the Cascadia accretionary complex. The geometry of this gas‐saturated bed is defined by a strong, negative‐polarity reflection in 3D seismic data. Because of the gas buoyancy, gas pressure equals or exceeds the overburden stress immediately beneath the GHSZ at the summit. We conclude that gas is focused into the coarse‐grained sequence from a large volume of the accretionary complex and is trapped until high gas pressure forces the gas to migrate through the GHSZ to seafloor vents. This focused flow provides methane to the GHSZ in excess of its proportion in gas hydrate, thus providing a mechanism to explain the observed coexistence of massive gas hydrate, saline pore water and free gas near the summit.

Publication Date

12-14-2004

Journal Title

Geophysical Research Letters

Publisher

American Geophysical Union (AGU)

Digital Object Identifier (DOI)

https://dx.doi.org/10.1029/2004GL021286

Document Type

Article

Rights

©2004. American Geophysical Union. All Rights Reserved.

Comments

This is an article published by AGU in Geophysical Research Letters in 2004, available online: https://dx.doi.org/10.1029/2004GL021286

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