Cruise inventory

RRS Discovery D93A

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74E3)
Cruise identifierD93A
Cruise period1978-05-26 — 1978-06-13
Port of departureLisbon, Portugal
Port of returnPonta Delgada, Portugal
ObjectivesThe main objectives of this cruise were two-fold. The first objective was a study of the deep crust and upper mantle structure associated with the Azores-Biscay Rise using seismic refraction and gravity profiles, Three refraction lines were planned to be shot on the crest and flanks parallel to the ridge axis while three gravity and seismic reflection profiles were to be obtained across the ridge. This work represented an extension of an already completed, and similarly executed, study of Kings Trough, in order to establish the relationship (if any) of Kings Trough to the anomalous Azores-Biscay Rise.
The second objective was a detailed study of crustal ageing along a flowline. The band between 45 and 46N east of the Mid-Atlantic Ridge was chosen for study, particuarly crust between 0 and 40million years old where the greatest ageing changes are believed to occur. The study was planned to consist of unreversed NS and reversed EW refraction profiles shot with a airgun and explosions out to 50kms range. An ancillary experiment was designed to seek for any azimuthal anisotropy in the upper part of young oceanic crust which is liable to be caused by cracks and fissures known to be preferentially orientated parallel to the Mid-Atlantic Ridge axis.
Chief scientistRobert B Whitmarsh (Institute of Oceanographic Sciences Wormley Laboratory)
Cruise reportRRS Discovery D93A cruise report d93.pdf — access key 'C' (0.77 MB) 
Ocean/sea areas 
GeneralNorth East Atlantic Ocean (limit 40W)
Track chartsRRS Discovery D93A cruise track — trk2055a.html RRS Discovery D93A cruise track — trk2055b.html RRS Discovery D93A cruise track — trk2055c.html RRS Discovery D93A cruise track — trk2055d.html RRS Discovery D93A cruise track — trk2055e.html RRS Discovery D93A cruise track — trk2055f.html
Physical oceanography 
Surface measurements underway (T,S)Quantity: track kilometres = 4445
Description: T only
Other physical oceanographic measurementsQuantity: number of profiles = 1
Description: sound velocity stations
Incident radiationQuantity: track kilometres = 4444.8
Routine standard measurementsQuantity: track kilometres = 4444.8
Other meteorological measurementsQuantity: number of observations = 4445
Description: sea and swell
Geology and geophysics 
Core - soft bottomQuantity: number of cores = 7
Single-beam echosoundingQuantity: track kilometres = 4445
Single channel seismic reflectionQuantity: track kilometres = 1850
Seismic refractionQuantity: number of stations = 6
Gravity measurementsQuantity: track kilometres = 4444.8
Magnetic measurementsQuantity: track kilometres = 4444.8