1,721,019 research outputs found
RRS Charles Darwin Cruise 23/87, 13 May - 11 June 1987. Geophysical investigation of the Indian Ocean Triple Junction
Full text linkRV Maurice Ewing Cruise EW9008, 29 Sep-26 Oct 1990. Sidescan sonar and swath bathymetry investigations of the Reykjanes Ridge, southwest of Iceland
Full text linkRRS Charles Darwin Cruise 33/38, 5 May - 1 June 1988. Geophysical and geological investigations of the Lau Back-Arc Basin, SW Pacific
Full text linkInfluence of sediment drift accumulation on the passage fop gravity driven sediment flows in the Iceland Basin, NE Atlantic
No full textThe Maury Channel is a deep-sea sediment transport system located in the Iceland Basin and extends from the Icelandic plateau southwards towards the Charlie-Gibbs Fracture Zone (CGFZ). This study has utilised multibeam bathymetry and multi-channel seismic reflection survey data along 480 km of its 1200 km pathway. In the northern reach of the channel it is predominantly broad (>20 km) and shallow (10 m). Further to the south the channel narrows (5–10 km) and locally deepens to 150 m prior to finally discharging onto the Eriador Plain to the north of the CGFZ. DSDP Site 115 in the Iceland Basin can provide insight into the evolution of the system as it sampled a suite of volcaniclastic turbidites of unequivocal Icelandic provenance. This sequence produces distinct amplitude anomalies on seismic reflection profiles allowing it to be mapped over an area of at least 26,000 km2. The southern edge of the high velocity unit is delimited by onlap onto the flanks of the Miocene (and younger) Gardar Drift. The drift appears to have initially acted as a barrier to southerly flows and promoted ponding of flows in the Maury Fan. Continued sediment supply from Iceland eventually filled the Maury Fan leading to the overspilling of the Gardar Drift dam. A result was the initiation of the Maury Channel. To the south of the drift, where the seabed is steep, flows are confined to the channel, whereas to the north of the drift, where the gradient is less, unconfined flow pathways dominate. The Maury Channel system highlights the interaction between turbidity currents and bottom currents on abyssal plains. The growth of sediment drifts not only mould the seafloor through their bathymetric development but also, through the building of seafloor topography, influence the passage and behaviour of gravity-driven sediment-laden flows along the seafloor.<br/
Seafloor topography and tectonic elements of the Western Indian Ocean
No full textThe break-up of Gondwanaland and dispersal of several of its component continental fragments, which eventually formed the margins of the Indian Ocean, have produced an ocean basin of enormous variety, both in relief and in origin of seafloor features. The western half of the Indian Ocean alone contains every type of tectonic plate boundary, both active and fossil, and, along with some of the deepest fracture zones, the most complex mid-ocean ridge configurations and some of the thickest sedimentary sequences in the world's ocean basins. This ocean is one of the most diverse on the face of the globe. We explore the evolution of the morphology of the Indian Ocean floor, and discuss the effect of its variations, maxima and minima, on the interconnectivity of the ocean's water masses. <br/
RRS "Charles Darwin" Cruise 169, 17 Feb-19 Mar 2005. Hydrothermal exploration of the southern Mid-Atlantic Ridge
Full text linkThe principal objective of this cruise was to identify the first site or sites of high temperature hydrothermal venting anywhere on the southern Mid-Atlantic Ridge, to characterize their geological setting, preliminary chemical nature and to identify, where possible, the nature of any vent-endemic species that might inhabit such vents to investigate whether this ridge system might represent a new biogeographic province. Initially we used the TOBI deep-tow sidescan system equipped with a CTD system and optical backscatter sensors, together with Miniature Autonomous Plume Recorders (MAPRs) to identify two new sites in which diagnostic chemically- and particle-laden plumes indicated the presence of high-temperature hydrothermal venting. Subsequently, we used the ABE autonomous underwater vehicle to (1) locate the core of one of these hydrothermal plumes, (2) obtain a detailed map of the underlying seafloor and (3) photograph three discrete hydrothermal sites (2 black-smoker systems, 1 diffuse-flow) and their associated ecosystems. A series of CTD stations were occupied for water column investigations and a number of rock-coring and dredging stations were also undertaken to provide groundtruthing of sidescan sonar images of the Mid-Atlantic Ridge seafloor
A compilation of geophysical data on the East Greenland continental margin and its use in gravity modelling across the continent-ocean transition
Full text linkNon-living Resources of the Continental Shelf Beyond 200 Nautical Miles: Speculations on the Implementation of Article 82 of the United Nations Convention on the Law of the Sea
No full textEffects on ridge segmentation, magmatic plumbing and eruption style caused by weak hot-spot to ridge interaction: the Central Indian Ridge and Rodriguez hot-spot couplet (abstract of paper presented at AGU Fall Meeting, San Francisco, CA, 10-14 Dec 2001)
No full textStructure and evolution of the South West Approaches and Grand Banks continental margins. Report of work undertaken by IOS during the period April 1975 to April 1984
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