Active seeping of fluids, including greenshouse gasses, from the accretionary wedge might influence global climate. Fluids also strongly influence the mechanics of faults in the wedge.
Description
Chief Scientists: Roland Von Huene, Ernst Flueh. Geophysical data (bathymetry, magnetics, bottomseismometer) of field activity S-97-94-WG in Western Gulf of Alaska from 07/28/1994 to 08/29/1994
Location
Western Gulf of Alaska
Summary
A camera sled with video and still cameras was used to verify the presence of clam and worm communities that are known to inhabit active seeps. Water and sediment samples were collected near the seeps. OBSs were deployed to measure the velocity of sediment to estimate the compaction and loss of porosity.
Comments
USGS contact: Mike Fisher (from 9/2/94 USGS Bulletin) During July the German research ship Sonne conducted geochemical and geophysical research in the Gulf of Alaska. Chief scientists Roland Von Huene and Ernst Flueh of GEOMAR in Germany were interested in measuring the flux of greenhouse gasses from the accretionary wedge near the Aleutian Trench. Multichannel seismic and Hydrosweep bathymetric data provided initial clues to locate potential fluid seeps, and the geochemists investigated likely sites using a video-camera sled. Although we found no obvious seeps, ever optimistic scientists hoped that the following cruise would identify additional sites for detailed analysis. Another research goal was to collect detailed seismic-velocity information from accreted rocks near the trench. From these data, geophysicists hoped to calculate gradients in the degree of compaction of accreted sediment as well as the volume of fluid expelled. The seismic source was two monstrous (2000 cu. in. each) air guns. Ten OBSs were deployed repeatedly with great success in this endeavor. Unfortunately, foul weather foiled our attempt to measure the seismic velocity of highly reflective rocks that form the middle and lower crust of the accretionary complex near lower Cook Inlet. The highlight of the cruise came with our realization that enigmatic features in USGS and Hydrosweep data revealed collision scars that resulted from subduction of seamounts and collision of the Yakutat terrane. Mike Fisher
Staff information imported from InfoBank
Roland Von Huene (USGS Western Region) - Chief Scientist
Ernst Flueh (GEOMAR) - Chief Scientist
