RRS Charles Darwin CD65
Cruise summary report
|Ship name (ship code)||RRS Charles Darwin (74AB)|
|Cruise period||1992-01-28 — 1992-03-01|
|Port of departure||Ponta Delgada, Portugal|
|Port of return||Ponta Delgada, Portugal|
|Objectives||1. Test the morphological inferences made from previously collected Sea Beam swath bathymetry of the median valley. For example, are seamounts identified on the Sea Beam maps identifiable as individual volcanoes on the TOBI images?
2. Define the different morphological styles of volcanism on the TOBI scale. Can the different styles and their associated textures be related to features observed at larger scales on Sea Beam maps and smaller scales on camera images?
3. Distinguish the differences between edifices generated by eruptions through pipes, and those generated by sustained fissure eruptions.
4. Infer the volcanic history of the inner valley floor from the stratigraphic relationships. For example, assess the degree of fracturing in neighbouring structures.
5. Determine how axial volcanic ridges are constructed. For example, are they composed of piled up seamounts and fissure-fed flows?
6. Obtain rock samples from neighbouring seamounts for geochemical analyses. Determine if they are derived from the same crustal magma body, and infer the magmatic plumbing system below the ridge.
7. Determine the relationship between volcanism and faulting. Do volcanism and faulting occur simultaneously?
8. Investigate the location and generation of new median valley fault scarps on the inner valley floor. Are axial volcanic ridges cut by median valley faults?
9. Survey an axial volcanic ridge that has been carried into the crestal mountains. Does the fossil axial volcanic ridge have the same morphology typical ofa ridge currently observed on the inner valley floor?
10. Determine the nature of the septa that divide separate magmatic segments.
11. Determine the extent and nature of small-scale magmatic segmentation.
|Chief scientist||Johnson R Cann (University of Leeds Department of Earth Sciences)|
|Project||British Mid-Ocean Ridge Initiative (BRIDGE)|
|Coordinating body||BRIDGE Steering Committee, NERC, UK|
|Cruise report||(7.83 MB)|
|General||North Atlantic Ocean|
|Specific||median valley of the mid-Atlantic Ridge;24N, 46W to 30N, 42W|
|Geology and geophysics|
|Dredge||Quantity: number of deployments = 35|
Description: Rock dredges for samples for petrological and geochemical analysis
|Bottom photography||Quantity: number of deployments = 8|
Description: IOSDL Bathysnap for volcanic forms
|Long/short range side scan sonar||Quantity: track kilometres = 540|
Description: Deep towed side-scan sonar (TOBI), images of volcanism/tectonics