Cruise inventory

RRS Shackleton S1/80

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Shackleton (74SF)
Cruise identifierS1/80
Cruise period1979-12-30 — 1980-01-28
Port of departureBombay, India
Port of returnKarachi, Pakistan
Objectives1) Find the crustal structure and the depth to the Moho beneath the Gulf of Oman abyssal plain and the Makran accretionary wedge, to test whether the crust is oceanic or continental and whether it dips northward beneath the Makran.

2) Investigate three dimensional structure of the ridges and intervening basins on the continental Makran margin using a closely spaced grid of continuous seismic reflection panels.

3) Take heat flow measurements to constrain the age of the crust, which is otherwise unknown, and to assist in interpretation of the prominent gas hydrate- free gas reflectors found in the area.

4) Make a detailed seismic survey across a localised accumulation of gas to test whether it is trapped by a phase change to gas hydrate as had been previously postulated.

5) Continue the reconnaissance survey of the Makran margin eastwards to the plate triple junction near Karachi to see whether subduction deformation persisits along the entire coast.

6) Survey the Murray Ridge, a prominent feature of unkown origin, using seismic reflection profiles, and underway gravity, magnetic and bathymetric measurements.
Chief scientistKeith E Louden (University of Cambridge Department of Earth Sciences)
Cruise reportRRS Shackleton S1/80 cruise report shackleton1_80.pdf — access key 'C' (0.62 MB) 
Ocean/sea areas 
GeneralGulf of Oman
Track chartsRRS Shackleton S1/80 cruise track — trk2624.html
Physical oceanography 
BathythermographQuantity: number of profiles = 4
Other physical oceanographic measurementsQuantity: number of profiles = 1
Description: sound velocity station
Geology and geophysics 
Core - soft bottomQuantity: number of cores = 4
Description: physical analysis of sediments
In-situ seafloor measurement/samplingQuantity: number of measurements = 4
Description: sea floor temperature
Multi-beam echosoundingQuantity: track kilometres = 4444.8
Single channel seismic reflectionQuantity: track kilometres = 4444.8
Seismic refractionQuantity: track kilometres = 370.4
Gravity measurementsQuantity: track kilometres = 4444.8
Magnetic measurementsQuantity: track kilometres = 4444.8