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RRS James Cook JC050
Cruise summary report
Cruise Info. | |
Ship name (ship code) | RRS James Cook (740H) |
Cruise identifier | JC050 |
Cruise period | 2010-07-18 — 2010-08-13 |
Status | Completed |
Port of departure | Reykjavík, Iceland |
Port of return | Birkenhead, United Kingdom |
Purpose | Research |
Objectives | This 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 scientist | Nicholas Jeremiah White (University of Cambridge Department of Earth Sciences) |
Project | Site Survey of V-Shaped Ridge Features |
Coordinating body | IODP/NERC |
Cruise report | (23.25 MB) |
Ocean/sea areas | |
General | North Atlantic Ocean |
Specific | Irminger and Icelandic seas, south of Iceland |
Track charts | (0.12 MB) |
Measurements | |
Physical oceanography | |
Bathythermograph | Quantity: 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 echosounding | Quantity: track kilometres = 3500 Description: Underway 3.5 kHz sub-bottom profiler, xyz, t, high resolution seabed mapping |
Multi-beam echosounding | Quantity: track kilometres = 3500 Description: Underway EA600, EM710, EM120, xyz, t, high resolution seabed mapping |
Multichannel seismic reflection | Quantity: 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 refraction | Quantity: number of deployments = 16 Description: Disposable Dowty sonobuoys: wide-angle seismic measurements, SEG-D, TWTT |
Gravity measurements | Quantity: track kilometres = 3500 Description: Underway gravity measurements, xyz, mgal, crustal modelling |
Magnetic measurements | Quantity: track kilometres = 3500 Description: Underway magnetic measurements, xyz, nT, crustal modelling |
Moorings, landers, buoys | |
Physical oceanography | |
Bathythermograph | 60° 34' 53" N 36° 9' 41" W — Sound velocity probe |
Geology and geophysics | |
Seismic refraction | 56° 0' 35" N 17° 55' 41" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 59° 50' 29" N 23° 10' 53" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 4' 47" N 26° 21' 53" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 7' 11" N 26° 41' 42" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 8' 17" N 27° 6' 41" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 9' 35" N 27° 28' 17" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 61° 45' 47" N 39° 40' 41" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 12' 54" N 28° 25' 41" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 37' 53" N 28° 30' 5" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 12' 54" N 29° 0' 5" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 17' 35" N 29° 38' 29" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 20' 29" N 30° 31' 59" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 23' 29" N 31° 26' 24" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 37' 59" N 36° 24' 29" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 12' 0" N 29° 9' 5" W — Disposable Dowty sonobuoy, not recovered |
Seismic refraction | 60° 11' 29" N 27° 56' 11" W — Disposable Dowty sonobuoy, not recovered |