Cruise inventory

RRS Discovery D275

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74E3)
Cruise identifierD275
Cruise period2003-10-28 — 2003-12-03
Port of departureFortaleza, Brazil
Port of returnFortaleza, Brazil
ObjectivesThe main aims of cruise D275 were as follows:
a) to determine the deep structure of the crust beneath the Amazon Cone and the shear-type margin to the south and the rift-type margin to the north;
b) to determine the thickness of stretched continental crust beneath the Cone load and, hence, its thermal history;
c) to determine the role (if any) of magmatism at the margin;
d) to determine the location of the ocean-continent boundary;
e) to determine the flexural rigidity, curvature, and, hence, amount of yielding in the basement beneath the Cone load.
Chief scientistAnthony B Watts (University of Oxford Department of Earth Sciences)
ProjectAmazon Cone Seismic Experiment - ACE
Cruise reportRRS Discovery D275 cruise report d275_03.pdf — access key 'C' (3.86 MB) 
Ocean/sea areas 
SpecificNE Brazil and French Guiana continental margin
Track chartsRRS Discovery D275 cruise track — d275_03trk.pdf (0.90 MB) 
Physical oceanography 
BathythermographQuantity: number of profiles = 11
Description: XBT deployments
Other physical oceanographic measurementsQuantity: number of profiles = 4
Description: sound velocity profiles
Routine standard measurementsQuantity: activity duration in days = 35
Description: standard surface met and navigation
Geology and geophysics 
Single-beam echosoundingQuantity: activity duration in days = 30
Description: 10 k Hz bathymetry using both towed fish and hull mounted SIMRAD EA 500. Data from both of limited quality
Single-beam echosoundingQuantity: activity duration in days = 30
Description: sub-bottom profiling with 3.5 k Hz fish mounted transducer. Data of limited quality.
Multichannel seismic reflectionQuantity: number of track lines = 6
Description: using Airgun array sound source and 2.4 km Teledyne analogue multichannel streamer
Gravity measurementsQuantity: activity duration in days = 35
Description: using a gyrostabilised Lacost-Romberg air-sea gravimeter (Model S-84)
Magnetic measurementsDescription: a Varian proton precission magnetometer was towed 200 m behind the ship during survey lines
Other geological/geophysical measurementsQuantity: 9
Description: land stations using SEIS-UK 6TD seismometers to extend velocity model landwards