RRS Charles Darwin CD75
Cruise summary report
|Ship name (ship code)||RRS Charles Darwin (74AB)|
|Cruise period||1993-01-06 — 1993-02-01|
|Port of departure||Port of Spain, Trinidad and Tobago|
|Port of return||Port of Spain, Trinidad and Tobago|
|Objectives||To 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 scientist||Graham K Westbrook (University of Birmingham School of Earth Sciences)|
|Cruise report||(1.02 MB)|
|General||North West Atlantic Ocean (limit 40W)|
|Geology and geophysics|
|Single-beam echosounding||Quantity: track kilometres = 1750|
Description: 10kHz wide beam echo sounder
|Single channel seismic reflection||Quantity: track kilometres = 900|
Description: 3.5kHz sub-bottom profiler
|Multichannel seismic reflection||Quantity: track kilometres = 900|
Description: 8-channel seismic reflection - 7 air gun array source
|Seismic refraction||Quantity: number of deployments = 26|
Description: digital seismometers on seabed up to 3 days