Cruise inventory

RRS James Cook JC024

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS James Cook (740H)
Cruise identifierJC024
Cruise period2008-05-23 — 2008-06-28
StatusCompleted
Port of departurePonta Delgada, Portugal
Port of returnSouthampton, United Kingdom
PurposeResearch
ObjectivesObjectives
1. To determine the life cycle of an AVR (estimates range from 10ka to 500ka).
2. To test whether the AVR ha a common parental magma derived from a single pulse of mantle melt.
3. To test whether AVRs develop systematically with an evolving volcanic style (e.g., sheet flows > pillow ridges > central volcanoes).
4. To determine how, if at all, these different volcanic components are linked. Are they derived successively from separate magma reservoirs? Are lateral terraces fed from axial vents?
5. To examine whether effusion rate and volume vary with time during AVR development. Are they reflected in volcanic style, run-out length and eruptive position within the AVR?
Summary
JC24 involved the first use of the ROV Isis on an active mid-ocean ridge axis. We departed Ponta Delgada on 23 May 2008 and finished in Southampton on 28 June. A breakdown of the Isis winch on 9 June required us to return to Ponta Delgada to pick up a spare part, involving a loss of four days. Altogether, we spent approximately 9.5 days on passage and 26.5 days on station at 45° 30'N, including one day lost due to bad weather. We completed a 6-day TOBI survey extending approximately 30 km along axis, completely insonifying the AVR with both north- and south-looking sidescan and phase data and obtaining three-component magnetic data on 22 E-W tracks spaced 1.5 km apart. Ship-based EM120 multibeam echosounder and gravity data were logged throughout the cruise, and sea-surface magnetometer was logged during the passage to and from the study area and during the TOBI survey. Eleven Isis sampling and video imaging dives were completed, and a further two dives carried out detailed bathymetry surveys. 270 rock samples were acquired. A WHOI three-component magnetometer was carried on all Isis dives.
The sidescan data were fully processed on board. In addition to the expected hummocky and flat-topped volcanoes, they revealed a number of lateral hummocky
Chief scientistRoger C Searle (University of Durham, Department of Earth Sciences)
Cruise reportRRS James Cook JC024 cruise report jc024.pdf — access key 'C' (5.58 MB) 
Ocean/sea areas 
GeneralNorth East Atlantic Ocean (limit 40W)
SpecificMid-Atlantic Ridge
Track chartsRRS James Cook JC024 cruise track — jc024trk.pdf (00 MB) 
Measurements 
Physical oceanography 
Other physical oceanographic measurementsQuantity: activity duration in hours = 234
Description: ISIS MAPR data
Other physical oceanographic measurementsQuantity: activity duration in hours = 31
Description: Tow-yo MAPR (Miniature Autonomous Plume Recorder) data, used for detecting hydrothermal plumes
Biology and fisheries 
Other biological/fisheries measurementQuantity: number of samples = 37
Description: Coral samples, for shore-based DNA analysis
Geology and geophysics 
Bottom photographyQuantity: activity duration in hours = 234
Description: ISIS video
Bottom photographyQuantity: number of images = 9788
Description: ISIS still photos
In-situ seafloor measurement/samplingQuantity: number of samples = 272
Description: Rock samples, half of each to each PI, to be used for shore-based major- and trace-element geochemistry and U-series dating
Geophysical measurements made at depthQuantity: survey square kilometres = 8
Description: ISIS 3-component magnetics
Geophysical measurements made at depthQuantity: survey square kilometres = 1200
Description: TOBI magnetics (3 component)
Geophysical measurements made at depthQuantity: survey square kilometres = 1200
Description: TOBI LSS (Light Scattering Sensor) data
Multi-beam echosoundingQuantity: survey square kilometres = 1200
Description: Ship-mounted EM120 with multibeam bathymetry
Multi-beam echosoundingQuantity: survey square kilometres = 8
Description: ISIS MS2000 high-resolution bathymetry
Long/short range side scan sonarQuantity: survey square kilometres = 1200
Description: TOBI sidescan sonar
Gravity measurementsQuantity: survey square kilometres = 1200
Description: Ship-based gravity
Magnetic measurementsQuantity: survey square kilometres = 1200
Description: Sea-surface magnetics
Other geological/geophysical measurementsQuantity: survey square kilometres = 1200
Description: TOBI phase bathymetry