RRS Discovery D275
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS Discovery (74E3) |
| Cruise identifier | D275 |
| Cruise period | 2003-10-28 — 2003-12-03 |
| Status | Completed |
| Port of departure | Fortaleza, Brazil |
| Port of return | Fortaleza, Brazil |
| Purpose | Research |
| Objectives | The 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 scientist | Anthony B Watts (University of Oxford Department of Earth Sciences) |
| Project | Amazon Cone Seismic Experiment - ACE |
| Cruise report |  (3.86 MB) |
| Ocean/sea areas | |
| Specific | NE Brazil and French Guiana continental margin |
| Track charts | (0.90 MB) |
| Measurements | |
| Physical oceanography | |
| Bathythermograph | Quantity: number of profiles = 11 Description: XBT deployments |
| Other physical oceanographic measurements | Quantity: number of profiles = 4 Description: sound velocity profiles |
| Meteorology | |
| Routine standard measurements | Quantity: activity duration in days = 35 Description: standard surface met and navigation |
| Geology and geophysics | |
| Single-beam echosounding | Quantity: 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 echosounding | Quantity: activity duration in days = 30 Description: sub-bottom profiling with 3.5 k Hz fish mounted transducer. Data of limited quality. |
| Multichannel seismic reflection | Quantity: number of track lines = 6 Description: using Airgun array sound source and 2.4 km Teledyne analogue multichannel streamer |
| Gravity measurements | Quantity: activity duration in days = 35 Description: using a gyrostabilised Lacost-Romberg air-sea gravimeter (Model S-84) |
| Magnetic measurements | Description: a Varian proton precission magnetometer was towed 200 m behind the ship during survey lines |
| Other geological/geophysical measurements | Quantity: 9 Description: land stations using SEIS-UK 6TD seismometers to extend velocity model landwards |
