Cruise inventory

RRS James Cook JC050

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS James Cook (740H)
Cruise identifierJC050
Cruise period2010-07-18 — 2010-08-13
StatusCompleted
Port of departureReykjavík, Iceland
Port of returnBirkenhead, United Kingdom
PurposeResearch
ObjectivesThis cruise was carried out under the auspices of an IODP Site Survey grant from NERC. There were two principal objectives. First, we were tasked with acquiring crossing seismic reflection profiles at a minimum of eight proposed IODP drilling targets on the V-shaped ridges and troughs which straddle the Reykjanes Ridge south of Iceland. Ancillary data (e.g. swath bathymetry, gravity, magnetics, hydrography (XBTs/XCTDs/SVP), sonobuoys, ADCP, EM710, EM120) were also required at each proposed site. Secondly, an important objective was acquisition of a long (~800 km) seismic reflection profile which was parallel to a flowline at right angles to seafloor spreading.

JC050 was preceded by a shake-down cruise (JC049) in which all of the scientific party participated. The purpose of this shake-down cruise was to ensure successful deployment and operation of the Spanish 2 km seismic streamer in preparation for JC050. We departed Reykjavik on 18/7/10 and steamed to start of line. Seismic surveying started on 20/7/10 and ended on 10/8/10. Weather conditions were generally good and only two minor periods of weather downtime occurred. From a technical perspective, the biggest problem we faced concerned the two airguns which were deployed on a single beam and operated at 3000 psi. During the early stages of acquisition, we found that the rear gun experienced damage from repeated collision with the beam. Despite numerous attempts at adjusting chain length and gun separation, we were forced to remove one gun and continue the survey with a single airgun. Nevertheless, data quality was not adversely affected. The primary objectives of JC050 were more than met. A total of 22 potential drilling targets were surveyed which will greatly enhance the planned IODP proposal. We also acquired a total of ~3000 line km which will enable a comprehensive analysis of the V-shaped ridges throughout the oceanic basin. Preliminary stacked seismic profiles were produced by onboard processing and indicated that we had collected a high quality and exciting dataset which is now being analyzed.
Chief scientistNicholas Jeremiah White (University of Cambridge Department of Earth Sciences)
ProjectSite Survey of V-Shaped Ridge Features
Coordinating bodyIODP/NERC
Cruise reportRRS James Cook JC050 cruise report jc050.pdf — access key 'C' (23.25 MB) 
Ocean/sea areas 
GeneralNorth Atlantic Ocean
SpecificIrminger and Icelandic seas, south of Iceland
Track chartsRRS James Cook JC050 cruise track — jc050trk.pdf (00 MB) 
Measurements 
Physical oceanography 
BathythermographQuantity: number of deployments = 35
Description: Expendable XBTs, XCTDs, XSVs, SVP. temperature/salinity/velocity, metres
Current profiler (eg ADCP)Quantity: track kilometres = 3500
Description: Underway current profiling to aid seismic oceanographic analysis
Geology and geophysics 
Multi-beam echosoundingQuantity: track kilometres = 3500
Description: Underway 3.5 kHz sub-bottom profiler, xyz, t, high resolution seabed mapping
Multi-beam echosoundingQuantity: track kilometres = 3500
Description: Underway EA600, EM710, EM120, xyz, t, high resolution seabed mapping
Multichannel seismic reflectionQuantity: track kilometres = 3500
Description: Underway data. SERCEL airgun and streamer, SEG-D, 10 S TWTT, generate vertical images of sub-sea bed down to sediment-basement interface.
Seismic refractionQuantity: number of deployments = 16
Description: Disposable Dowty sonobuoys: wide-angle seismic measurements, SEG-D, TWTT
Gravity measurementsQuantity: track kilometres = 3500
Description: Underway gravity measurements, xyz, mgal, crustal modelling
Magnetic measurementsQuantity: track kilometres = 3500
Description: Underway magnetic measurements, xyz, nT, crustal modelling
Moorings, landers, buoys 
Physical oceanography 
Bathythermograph60° 34' 53" N  36° 9' 41" W — Sound velocity probe
Geology and geophysics 
Seismic refraction56° 0' 35" N  17° 55' 41" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction59° 50' 29" N  23° 10' 53" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 4' 47" N  26° 21' 53" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 7' 11" N  26° 41' 42" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 8' 17" N  27° 6' 41" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 9' 35" N  27° 28' 17" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 11' 29" N  27° 56' 11" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 12' 54" N  28° 25' 41" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 37' 53" N  28° 30' 5" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 12' 54" N  29° 0' 5" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 17' 35" N  29° 38' 29" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 20' 29" N  30° 31' 59" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 23' 29" N  31° 26' 24" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction61° 45' 47" N  39° 40' 41" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 12' 0" N  29° 9' 5" W — Disposable Dowty sonobuoy, not recovered
Seismic refraction60° 37' 59" N  36° 24' 29" W — Disposable Dowty sonobuoy, not recovered