RRS Discovery D54

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74E3)
Cruise identifierD54
Cruise period1973-06-29 — 1973-08-15
Port of departureSouthampton, United Kingdom
Port of returnBarry, United Kingdom
Objectives1) To use GLORIA to make a long range side-scan sonar survey of an area on the Mid-Atlantic Ridge SW of the Azores.

2) Camera travases were planned across features revealed by the GLORIA survey to identify the nature of targets giving acoutsic echoes.

3) Seismic lines using pop-up bottom seismic recorders were planned in the median valley to determine the structure and to locate the magma chamber, in the neighbouring ridges and across the valley. Microearthquakes were expected during recording time.

4) A site for drilling into layer 2, to be occupied by the Deep Sea Drilling Project in the summer of 1974, requires adequate sediment for initial support of the bottom hole assembly. Seismic reflection profiles and a seismic refraction line were planned to locate a suitable site.

5) It was the intention to obtain as much coverage with GLORIA on passage as possible, especially on the route across the Azores plateau near the mid-Atlantic Ridge and along the Azores-Gibraltar plate boundary, and fracture zones south of this.

6) Profiling at 7-10 knots was planned whenever time allowed.

7) The reversal of a refraction line shot by HMS Hecla in April 1973

8) Electrodes were to be towed along the bottom in the FAMOUS area as part of a Cambridge University research project

9) These were to be made throughout the cruise to add to the study of the bathymetry and magnetic and anomaly field of the Northeast Atlantic

10) Vertical profiles of velocity of sound in the sea are required for the interpretation of both GLORIA and PUBS results and were made to be as required.
Chief scientistAnthony S Laughton (Institute of Oceanographic Sciences Wormley Laboratory)
Cruise reportRRS Discovery D54 cruise report d54.pdf (1.13 MB)  RRS Discovery D54 cruise report d54_data_report.pdf (6.02 MB) 
Ocean/sea areas 
GeneralNorth Atlantic Ocean
Track chartsRRS Discovery D54 cruise track — d54_data_reporttrack.pdf (0.56 MB)  RRS Discovery D54 cruise track — d54track.pdf (0.31 MB) 
Physical oceanography 
Other physical oceanographic measurementsQuantity: number of profiles = 2
Description: Velocimeter for sound velocity
Occasional standard measurements
Geology and geophysics 
Bottom photographyQuantity: number of deployments = 2
Description: Towed buoyant mini camera
In-situ seafloor measurement/samplingQuantity: number of deployments = 3
Description: Bottom towed electrodes
Single-beam echosoundingQuantity: activity duration in days = 41
Description: PES
Long/short range side scan sonarQuantity: track kilometres = 6000
Description: GLORIA
Single channel seismic reflectionQuantity: track kilometres = 7000
Seismic refractionQuantity: number of stations = 5
Description: PUBS deployments
Magnetic measurementsQuantity: activity duration in days = 37
Description: Varian V-75 magnetometer