Other ID: 130-1
Organization(s): USGS, Woods Hole Coastal and Marine Science Center
Location: Mohns Ridge, Mid-Atlantic Ridge, Norwegian Sea, North Atlantic;
Principal Investigator(s): William Schwab
Data Type(s): Sonar: Sidescan, Seismics: Sub Bottom Profiler, Imagery: Photo, Imagery: Video, Sampling: Geology, Location-Elevation: Navigation, Location-Elevation: Transects
Scientific Purpose/Goals: The neovolcanic zone of a section of the Mohns Ridge will be mapped. Specific interest is to investigate the possibility of hydrothermal activity. If this activity is found, an instrument package will be used to measure the thermodynamic index properties of the venting fluids. If time allows, Vesterisguinnen will be investigated also for hydrothermal activity.
Start Date: 1987-08-02
Start Port/Location: Bodo, Norway
End Date: 1987-08-20
End Port/Location: Reykjavik, Iceland
Equipment Used: SeaMARC sidescan sonar system, 4.5 kHz, ARGO, Loran-C, GPS (wh), Magnavox satellite positioning system, Benthos 7000
Information to be Derived:
Summary of Activity and Data Gathered: Mohns Ridge is an area of sea-floor spreading and associated volcanic activity (Vogt and others, 1982). As with other mid-ocean ridge systems, the recent or fresh volcanic activity along Mohns Ridge is discontinuous, both temporally and spatially. The question that remains is what are the odds of finding a high-temperature hydrothermal vent on Mohns Ridge? The findings of this cruise suggest that hydrothermal activity has taken place on Mohns Ridge. The presence of temperature anomalies, sediment elutriation structures in rippled, bioturbated sediment, and a water-column density plume suggest that Area 1 was hydrothermally active at the time of this investigation. Although the evidence suggests hydrothermal activity, the existence of a black smoker on Mohns Ridge is not guaranteed by the findings of this cruise. Area 1: 395 sq km SeaMARC data, 106 hrs ARGO pix; Area 2: 5.5 hrs ARGO (bioturbated rippled sediment); Area 3: 275 sq km SeaMARC data, 56.2 hrs ARGO pix, 222 km bathymetry.
Staff: William Schwab
Schwab, W.C., Holcomb, Robin T., and van Dover, Cindy L., 1988, Preliminary presentation and interpretation of ARGO/SeaMARC 1B reconnaissance investigation of Mohns Ridge, Norwegian Sea: U.S. Geological Survey Open-File Report 88-23, 21 p. URL: http://pubs.er.usgs.gov/usgspubs/ofr/ofr8823.