1,721,052 research outputs found
RRS James Cook Cruise 10, 13 May-07 Jul 2007. Hotspot ecosystems in the NE Atlantic, UK contribution to the HERMES Project. Mud volcanoes in the Gulf of Cadiz; submarine canyons west of Portugal; submarine canyons in the northern Bay of Biscay
Full text linkThe major objective of RRS James Cook Cruise 10 was to increase our understanding of how seafloor environmental variables affect the biodiversity, structure, function and dynamics of faunal communities in two specific ‘biological hotspot’ environments, mud volcanoes and submarine canyons, on the NE Atlantic continental slope. The cruise was jointly supported by OCEANS 2025 (Theme 5) and the EU Hotspot Environmental Research on the Margins of European Seas (HERMES) Project. The work was based mainly on the use of the Remotely Operated Vehicle (ROV) ISIS, but a wide suite of additional techniques including sediment coring, water column measurement and sampling, benthic trawling and swath mapping were also deployed. Forty-one ROV dives, some lasting for up to 36 hours, were completed during a highly successful cruise. The ROV programme included swath mapping, video and still photography, sediment coring using both push and mini-box corers, rock sampling, collection of biological samples, water sampling, subseafloor temperature measurement, and the placing and manipulating of a variety of seafloor experiments
RRS "Discovery" Cruise D297, 27 Jul - 16 Aug 2005. The geobiology of the Nazare and Setubal Canyons, Portuguese Continental Margin
Full text linkThe main objective of this cruise was to complete the geological survey of the Setubal and Nazare canyons including more sidescan sonar survey in the canyon mouths and on the lower continental rise north of the mouth of Setubal mouth. Other major objectives were to carry out sampling of the seabed for meio and macro fauna at 3 depth transects in each canyon; to run a series of SHRIMP video runs in the canyons at different depths to quantify the seabed organisms; to measure the amount and type of particulate matter in the water column, particularly near the seabed at the study sites, and to investigate the benthic ichthyofauna and bioluminescence using bottom landers.This cruise provided data for the EU FP6 project HERMES (Hotspot Ecosystem Research on the Margins of European Seas), as well completing work for the EU FP5 project EUROSTRATAFORM
RRS Discovery Cruise 249, 19 Aug-10 Sep 2000. History of sedimentation in the Gulf of Cadiz: investigations with the SOC giant piston corer
Full text linkThis was the third cruise using the new SOC giant piston corer. The objectives were to complete the testing of the giant piston corer which was begun on cruise D219 in November/December 1995 and cruise D225 in February/March 1997, and to collect giant piston cores from the Gulf of Cadiz on sites selected from the TOBI survey carried out on cruise D244 in December 1999. As on previous cruises we had problems with both the ships equipment (outboard sheave on coring gantry), and the giant piston corer. The sheave problem necessitated 2.5 days in port plus transit time. This combined with some weather downtime severely limited the amount of work which could be carried out. Nevertheless, we resolved some coring issues, especially proving that elastic rebound of the kevlar is not a major problem. We also managed to take a consistent series of good cores with a 15 metre barrel, and although all the 27 metre barrel cores bent, the bending took place above the sediment surface leaving a good quality core below. The longest core recovered was 18.1 metres and 21 cores were obtained in all. The cruise also involved testing the scatterometer. This proved to be a failure due to multiple electronic problems and no data was recorded in any of its two deployments
Northwest African Continental Margin: history of sediment accumulation, landslide deposits, and hiatuses as revealed by drilling the Madeira Abyssal Plain
No full textODP drill sites in the Madeira Abyssal Plain reveal sequences of organic-rich turbidites derived from the northwest African margin, in which each turbidite has a volume of tens to hundreds of cubic kilometers. The frequency of turbidite emplacement has been combined with core and seismic data to show the volume of redeposited sediment. The basin began to fill about 22 Ma with numerous small turbidites, up to 100 per million years, each with volumes of a few cubic kilometers. The total volume of turbidites deposited increased between 16 and 11 Ma, as did their individual volumes, and then declined to 7 Ma. At 7 Ma, there was a dramatic increase in the amount of turbidite input to 768 km3/Myr and a rise in the average volume of each unit to 59 km3. These high values have been maintained to the present day. The variations in the amount of redeposited sediment most likely reflect the rates of sedimentation on the northwest African margin since high sedimentation leads to oversteepening of the slopes and eventual mass wasting. The dramatic changes at about 7 Ma may be due to a large increase in upwelling off northwest Africa caused by circulation changes associated with increased glaciation of the poles. Up to 20% of sediment may be remobilized by landslides, with each event leaving a hiatus. Each of these hiatuses extends over an average area of ?4800 km2 and represents removal of sediment layers several tens of meters thick and of several hundred thousand years duration
RRS Charles Darwin Cruise CD157, 28 May - 13 June 2004. Sediment transport through the Setubal and Nazare Canyons
Full text linkThe main objective of the cruise was to groundtruth the sidescan sonar coverage of the Setubal and Nazare Canyons that was collected on the RV Pelagia in November 2003. A range of corers including box, mega, kastenlot and piston provided a range of possibilities to core sediment of varying grainsize from gravel to mud. In addition a deeptowed profiler was used to collect subsurface profiles across the canyons, but plans to use SHRIMP were abandoned due to problems with the conducting cable. The coring was a success given the difficult topography; site location was aided by the TOBI sidescan survey completed in 2003, making it possible to hit relatively small targets just a few hundred metres across. Careful choice of corer type ensured core recovery in the sequence of mixed sands and muds. No corers worked well in the Nazare thalweg due to presumed hard or sandy seabed.The data will be used to groundtruth the TOBI sidescan and to determine the flux of sediment through the Setubal and Nazare Canyons. Initial interpretations suggest significant differences between the canyons and strong changes in the amount of activity with time
RRS Discovery Cruise 225, 24 Feb-07 Mar 1997. Studies of mass wasting in the Agadir Basin and sediment transport in the Gulf of Cadiz - incorporating trials of the giant piston corer
Full text linkThis was the second cruise using the new SOC giant piston corer. The objectives were to complete the testing of the giant piston corer which was begun on cruise D219 in November/December, 1995 and to collect giant piston cores from the Agadir Basin, Gulf of Cadiz and Portuguese margin. We showed that the original problems with the ship's gantry have been overcome and that the ship is now capable of handling the loads experienced during deployment and especially pullout. A large number of relatively minor problems were experienced during the cruise with the design and configuration of the corer. We worked through these systematically until cores were being obtained on a regular basis. A total of 9 cores were obtained from 14 coring attempts. The longest core was 15.97 m long. The quality of cores recovered was excellent
Stratigraphy and palaeoenvironmental analysis of cores taken during "Discovery" Cruise 118, N.E. Atlantic
No full textRRS Discovery Cruise 187, 20 October - 20 November 1989. Geological and geochemical investigations in the Tagus, Horseshoe and Seine Abyssal Plains
Full text linkRRS Discovery Cruise 219, 28 Nov-11 Dec 1995. Mass wasting off Portugal and the Canary Islands - investigation by giant piston coring
Full text linkCruise D219 was beset with problems - bad weather, the need to transfer seamen to port on two separate occasions for compassionate reasons, combined with the need for further trials of the coring system limited our coring attempts to 6 deployments of which only one produced a core. After only 12 days at sea considerable wear was detected on the ship's coring gantry making it unsafe for further work. The cruise was therefore terminated one week early. Nevertheless, we believe that the corer will work and produce good quality cores when the problems with the ship have been rectified
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