Sperus 7/77 Leg 7
Cruise summary report
|Ship name (ship code)||Sperus (74TJ)|
|Cruise identifier||7/77 Leg 7|
|Cruise period||1977-07-03 — 1977-07-15|
|Port of departure||South Shields, United Kingdom|
|Port of return||Lerwick, United Kingdom|
|Objectives||Geological and geophysical mapping of the UK Continental Shelf.
It was planned to survey in four areas with the following priority:
1. 1:250 000 Cormorant Sheet (61-62° N, 0-2° E).
2. West of Shetland in 1:250 000 Shetland Sheet (60-61° N, 2-0° W).
3. Additional data was required to complete interpretation of 1:250 000 Sutherland Sheet (58-59° N, 6-4° W).
4. 1:250 000 Halibut Bank Sheet (60-61° N, 0-2° E).
Areas 1, 2 and 4 would be surveyed along a regular grid of lines - N-S at 13km spacing and E-W at 8km spacing. Areas 1 and 2 had top priority because these areas are programmed for sampling by Continental Shelf Unit North (CSU N) in 1978. After completion of areas 1 and 2, depending on time remaining, a decision would be made on whether or not to attempt survey of area 3.
Three small additional survey jobs had been requested:
a) A 250km sparker survey to clarify outcrop of base Upper Cretaceous in North Sea Quadrant 42 off the Yorkshire coast.
b) A 300km regional survey extension east off Shetland between 60degN and 60deg20'N.
c) A 300km gravity, magnetic and airgun survey to investigate a possible Tertiary igneous centre west of the Cormorant Sheet.
A small sparker survey 300km was carried out in Quadrant 42 to provide shallow seismic data.
Good pinger and echo-sounder records obtained in the Forties area.
For surveying the sparker, airgun, side scan sonar, pinger, echo-sounder and magnetic equipment were used concurrently.
An extension of the survey line was made over an area of a large magnetic anomaly.
|Chief scientist||A Dobinson (Institute of Geological Sciences, Edinburgh)|
|Cruise report||(18.20 MB)|
North East Atlantic Ocean (limit 40W)
|Track charts||(0.39 MB) (0.21 MB) (0.70 MB)|
|Geology and geophysics|
|Single-beam echosounding||Description: regional geophysical survey|
|Long/short range side scan sonar||Description: regional geophysical survey|
|Long/short range side scan sonar||Description: format: seismic graphic recorder; regional geophysical survey|
|Single channel seismic reflection||Description: pinger.Format: seismic graphic recorde. Regional geophysical survey.|
|Multichannel seismic reflection||Description: wide angle reflection.Format: seismic graphic recorder. Regional geophysical survey|
|Seismic refraction||Quantity: track kilometres = 300|
Description: small sparker survey
|Gravity measurements||Description: format: seismic graphic recorder; regional geophysical survey|
|Magnetic measurements||Description: format: seismic graphic recorder; regional geophysical survey|