TRYON, M. D., and K. M. BROWN
Scripps Institution of Oceanography, La Jolla, CA

Abstract: Aqueous Flux Measurements on Hydrate Ridge, Cascadia

We present results from aqueous flux measurements taken on Hydrate Ridge in the Cascadia accretionary prism during the TECFLUX 98 program, August-September, 1998. The main objective of this program is to determine the effects of widespread formation and local destruction of gas hydrates in this area on element mobilization, transport, and release at the seafloor. The determination of the magnitude and distribution pattern of aqueous flux is a key element in this objective. Measurements were taken over a one month period using eight SIO Benthic Aqueous Flux Meters. These instruments use the dilution of a chemical tracer to record a time series of flux rates. Data analysis is continuing at this time. Five instruments were deployed by the ROPOS ROV in and around areas of microbial mats and clam colonies, indicative of areas of active flow, near the northern summit of the ridge. Preliminary results indicate that flow is heterogeneous, with areas of both upflow and downflow. Significant changes in the magnitude of the flow was also noted on one instrument. Three instruments were also deployed near the southern summit where extensive gas hydrates occur but with no obvious surface indicators for seepage. Flow rates in this region varied from very little flow on the upper flanks of the ridge to apparently highly elevated upward flow on the summit in a region where very shallow gas hydrate deposits were identified during a previous R/V SONNE cruise.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California