USGS Coastal and Marine Geology Program

Coastal & Marine Geology Program

Field Activity Details for field activity 1987-033-FA

Other ID: 130-1

Status: Completed

Organization(s): USGS, Woods Hole Coastal and Marine Science Center

Funding Program(s):

Location: Mohns Ridge, Mid-Atlantic Ridge, Norwegian Sea, North Atlantic;

Principal Investigator(s): William Schwab

Affiliate Investigator(s):

Information Specialist(s):

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

Affiliate Staff:
Robin T. Holcomb - Geologist
USGS-Seattle; Harold D. Williams - Marine Tech.
USGS-Denver; B.D.M. Corporation: Jeffrey C. Hoy - Sponsor Rep.
Richard A. Gallotta - Sponsor Rep.; Colmek Systems Engineering: Dale R. Kendall - Engineer
Brent R. Miller - Engineer; Lockheed M&S Div.: David J. Mendez - Engineer
Paul R. Ferguson - Engineer; Marine Imaging Systems: Robert H. Squires - Engineer; U.S. Navy: Ronald G. Bowlin - Marine Tech.
Josef R. Labermeyer - Sonar Tech.; WHOI: Cindy L. van Dover - Biologist
William N. Lange - Data Curator
Thomas K. Dettweiler - Senior Engineer
Stephen R. Gegg - Navigator
Earl M. Young - Marine Tech.
Thomas Crook - Navigator

Project = Mid-Ocean Ridge Research, Mid-Ocean Ridge Research

Location Map:


photo of Knorr


Data Acquired

Survey EquipmentSurvey InfoData Type(s)Data Collected
SeaMARC sidescan sonar system --- Sidescan
4.5 kHz --- Sub Bottom Profiler
ARGO --- Photo
Loran-C --- Navigation
GPS (wh) --- Navigation
Magnavox satellite positioning system --- Navigation
Benthos 7000 --- Navigation