Extrusive and intrusive magmatism in the North Rockall Trough

2005 ◽  
Vol 6 (1) ◽  
pp. 1621-1630 ◽  
Author(s):  
K. THOMSON
Author(s):  
R. J. Whittington ◽  
M. R. Dobson

Single channel, analogue, seismic reflection profiles using Sparker and small capacity Air gun sources were used to investigate late Tertiary and Quaternary sedimentation both around the margins and on the floor of the north Rockall Trough. The data complement, by being intermediate in penetration and resolution, previous seismic studies; particularly, they allow the upper 500 m of the sediment sequence to be examined in greater detail than hitherto.


1995 ◽  
Vol 52 (S1) ◽  
pp. 90-94 ◽  
Author(s):  
David I. Gibson

An opecoelid digenean parasite, Allopodocotyle margolisi n.sp., is described from the macrourid fish Coryphaenoides (Chalinura) mediterraneus from benthopelagic waters of the North Rockall Trough, NE Atlantic Ocean. This is the first member of the genus to be recorded from deep-sea fishes. It is distinguished from its neritic congeners on the basis of features that include the arrangement of the testes, length of the cirrus-sac, and sucker-ratio. Its distinctness from other opecoelids from deep-sea fishes is also commented upon.


During the Joint Air-Sea Interaction Experiment (JASIN 1978) grids of temperature and salinity profiles were worked within an area of about 150 km x 150 km to obtain details of the mesoscale circulation around the location of the experiment in the North Rockall Trough. Data were also obtained from moored current meters and from research vessel observations in the surrounding waters. In the uppermost layers two water masses were present, North Atlantic Water from southern parts of the Rockall Trough and fresher Modified North Atlantic Water from the north and west. Beneath these an intermediate water formed by Atlantic Water in contact with Subarctic Intermediate Water was found and at greater depth distinctions could be drawn between water from the south, water with an admixture of Norwegian Sea Deep Water from the Scotland-Iceland ridges and, more sparse, water with a component of Arctic Intermediate Water from the Faroe-Shetland Channel. The patterns of circulation were found to change little between the lower depths and 200 m. An anticyclonic eddy of fresher, colder water moved westwards across the northern half of the grid at about 1.4 km day-1, the northern sector of a more saline meander expanded westwards across the southern part of the area, and smaller less well resolved circulations were found in the west. The eddy contained water of overflow origin and the meander appears to have been part of the main Atlantic to Norwegian Sea current. When inverse analysis was applied to two of the data sets to investigate choices of reference level, zero velocity at the bottom gave the only physically realistic solution. Although the necessary process of averaging the observations to data points 45 km apart obscured the resolution of smaller features, confidence in the reference level that satisfied the inverse analysis allowed classical geostrophic analysis to be performed on the full set of stations, supporting and quantifying the earlier analysis of patterns. The influence of the deeper circulation can be seen in the modification of the thermohaline structure in the seasonal thermocline and mixed layers. Boundaries between adjacent upper water masses were distorted by underlying convergences or fragmented by horizontal shears.


2020 ◽  
Author(s):  
Loïc Houpert ◽  
Stuart A. Cunningham ◽  
Neil J Fraser ◽  
Clare Johnson ◽  
N. Penny Holliday ◽  
...  

Author(s):  
Rhian G. Waller ◽  
Paul A. Tyler

Gametogenesis and reproductive periodicity of the solitary scleractiniansFlabellum alabastrum(from the Rockall Trough) andF. angulare(from the Porcupine Seabight) were investigated. Samples were collected between depths from 1370 to 2190 m forF. alabastrumand 2412 to 2467 m forF. angulare. Both species showed gonochorism with a 1:1 sex-ratio and broadcast spawning of gametes is inferred from the lack of brooded planulae. Oocyte sizes were large in both species (925 μm inF. alabastrumand 1015 μm inF. angulare), suggesting lecithotrophic larval development. Fecundity and periodicity of oocyte development differed between the two species.Flabellum alabastrumproduced a maximum of 2800 oocytes per polyp quasi-continuously, whereas the deeper speciesF. angulareproduced a maximum of 550 oocytes per polyp either seasonally or periodically. Both species showed size-dependent fecundity. The data show a decrease in oocyte size and fecundity with depth, in concordance with other deep-water scleractinian species.


2020 ◽  
Author(s):  
Loïc Houpert ◽  
Stuart A. Cunningham ◽  
Neil J Fraser ◽  
Clare Johnson ◽  
N. Penny Holliday ◽  
...  

Author(s):  
J. Mauchline

SynopsisA brief historical account of the early faunal investigations is given. Modern studies concentrate on qualitative and quantitative description and interpretation of the processes taking place within the Rockall Trough. Demographic analyses are feasible on a variety of species allowing estimation of growth and production rates. The pelagic fauna impinges on the benthopelagic environments of the slope regions of the Trough. There it is predated by populations of demersal fish. Advection of fauna takes place to the north and northeast, probably primarily in the slope current.


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