Cruise inventory

RRS Charles Darwin CD75

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Charles Darwin (74AB)
Cruise identifierCD75
Cruise period1993-01-06 — 1993-02-01
Port of departurePort of Spain, Trinidad and Tobago
Port of returnPort of Spain, Trinidad and Tobago
ObjectivesTo conduct seismic experiments at four sites in two areas to determine the effects of the accretion of sediment into an accretionary wedge upon the porosity and pore-fluid pressure of the accreted sediments and the sediments thrust beneath the wedge.
In each area, measurements of P-wave and S-wave velocities from a site on the undisturbed ocean floor in front of the accretionary wedge were to be compared with measurements taken from a site on the toe of the accretionary wedge.
In addition it was hoped that changes in the seismic anisotropy of the sediments could be distinguished between the two sites.
Grids of seismic reflection profiles were run to define the slopes of layers and show where sediments were deformed.
Chief scientistGraham K Westbrook (University of Birmingham School of Earth Sciences)
Cruise reportRRS Charles Darwin CD75 cruise report cd75.pdf — access key 'C' (1.02 MB) 
Ocean/sea areas 
GeneralNorth West Atlantic Ocean (limit 40W)
Specific1520N-1540N;5830W-5855W, 1415N-1435N;5725W-5755W
Track chartsRRS Charles Darwin CD75 cruise track — trk3859.html
Geology and geophysics 
Single-beam echosoundingQuantity: track kilometres = 1750
Description: 10kHz wide beam echo sounder
Single channel seismic reflectionQuantity: track kilometres = 900
Description: 3.5kHz sub-bottom profiler
Multichannel seismic reflectionQuantity: track kilometres = 900
Description: 8-channel seismic reflection - 7 air gun array source
Seismic refractionQuantity: number of deployments = 26
Description: digital seismometers on seabed up to 3 days