scholarly journals Paleoecology of Late Eocene-Oligocene foraminiferal assemblages in a two-well transect across the North-East Newfoundland shelf

1991 ◽  
Vol 10 (1) ◽  
pp. 57-67
Author(s):  
F. C. Thomas
Keyword(s):  
North Sea ◽  
Late Eocene ◽  
Western Boundary ◽  
Late Oligocene ◽  
North East ◽  
The North ◽  
Early Oligocene ◽  
The North Sea ◽  
Relationship Of ◽  
The Relationship

Abstract. Core samples from the Paleogene of the Bonavista C-99 well on the northeast Newfoundland shelf and cuttings from downdip Blue H-28 contain foraminiferal assemblages which enable reconstruction of paleoenvironments along a downslope transect in Eocene through Late Oligocene-Miocene time. Comparison with coeval assemblages in North Sea wells with respect to structure and grain size of agglutinated taxa between the two areas reveal inter-basin differences.Reconstruction of the paleobathymetry derived from foraminiferal analysis, confirms seismic evidence for shallowing at the Bonavista site beginning in the Early Oligocene. The relationship of the Bonavista assemblages to contour currents is explored with reference to modern regional analogues. Species such as Reticulophragmium amplectens, Haplophragmoides walteri, Eponides umbonatus and Uvigerina ex. gr. miozea-nuttalli persist stratigraphically higher in the deeper Blue site.The paleoslope of this two-well transect is determined as approximately 0.48° during the Middle to Late Eocene and 0.68° during the Late Oligocene-Early Miocene. The bottom water hydrography of the transect can be evaluated by reference to these assemblages and a comparison to flysch-type agglutinated assemblages from a transect in the North Sea. The presence of an Upper Eocene-Middle Miocene hiatus at the Blue site contrasting with apparently continuous Tertiary deposition at Bonavista places a theoretical upper limit of 500–1000 m on the depth of the early Cenozoic western boundary undercurrent.

scholarly journals Late Cenozoic basin development of the eastern North Sea Basin

1996 ◽  
Vol 43 ◽  
pp. 9-21
Author(s):  
Olaf Michelsen
Keyword(s):  
North Sea ◽  
Late Eocene ◽  
The North ◽  
Early Oligocene ◽  
Late Middle Miocene ◽  
Transport Direction ◽  
Near Shore ◽  
The North Sea ◽  
Central North Sea ◽  
First Time

The Cenozoic succession in the Danish part of the North Sea Basin includes two significant breaks in sedimentation; 1) at the Eocene-Oligocene boundary and 2) at mid Miocene time. The sediment transport direction was from the west during the Middle-Late Eocene and mainly from northeast and east in post Eocene times, and a change from a concordant seismic reflection pattern to a progradational pattern is seen. A clear change in Iithology occurs at the Eocene-Oligocene boundary, from a finegrained clay-dominated deposit below the boundary to a clay with silt and mica above. Near shore marine and fluvial sediments of Early Oligocene to mid Miocene age are known from the offshore and onshore areas, witnessing that the coastline migrated into the basin for the first time since the earliest Cretaceous. This change in sedimentation pattern was probably caused by the initial uplift of Scandinavia. At mid Miocene time a significant environmental change occurred in the North Sea. A change from dark coloured to light coloured deposits indicates introduction of a well-oxygenated environment. A marked increase in rate of sedimentation (and subsidence) is evidenced by the approx. 1500 m thick sedimentary package in the central part of the basin. Late Middle Miocene starved sedimentation seen in the central North Sea may indicate a significant increase in subsidence rates. The base of the Quaternary is a major erosional unconformity, mainly created by erosion caused by uplift of Scandinavia. 1000-1200 m of uplift is calculated for the eastern part of the North Sea Basin. With a post-Eocene subsidence of 2500 m in the central North Sea, the amplitude of the post-Eocene tectonic movements is approx. 3700 m.

Further Investigation upon the Water Movements in the English Channel. Drift-Bottle Experiments in the Summers of 1927, 1928 and 1929, with Critical Notes on Drift-Bottle Experiments in General.

1930 ◽  
Vol 17 (1) ◽  
pp. 241-275 ◽  
Author(s):  
J. N. Carruthers
Keyword(s):  
Wind Speed ◽  
North Sea ◽  
English Channel ◽  
The North ◽  
Different Types ◽  
The North Sea ◽  
The Common ◽  
Relationship Of ◽  
Great Simplicity ◽  
Simple Surface

In July–August of three different years common surface-floating bottles were set adrift at International Station E2 (49° 27' N.—4° 42' W.). With them, various types of drag-fitted bottles were also put out. The journeys accomplished are discussed, and the striking differences as between year and year in the case of the common surface floaters, and as between the different types in the same year, are commented upon in the light of the prevailing winds. An inter-relationship of great simplicity is deduced between wind speed and the rate of travel of simple surface floating bottles up-Channel and across the North Sea from the results of experiments carried out in four different summers.

Exceptional influx of oceanic species into the North Sea late 1997

1999 ◽  
Vol 79 (4) ◽  
pp. 737-739 ◽  
Author(s):  
M. Edwards ◽  
A.W.G. John ◽  
H.G. Hunt ◽  
J.A. Lindley
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Climatic Conditions ◽  
Historical Evidence ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Oceanic Species

Continuous Plankton Recorder records from the North Sea and north-east Atlantic from September 1997 to March 1998 indicate an exceptional influx of oceanic indicator species into the North Sea. These inflow events, according to historical evidence, have only occurred sporadically during this century. This exceptional inflow and previous inflow events are discussed in relation to their similarity in terms of their physical and climatic conditions.

scholarly journals Ovary resorption in the Norway lobster (Nephrops norvegicus) and its possible causes with special reference to sperm storage

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Carola Becker ◽  
Jaimie T. A. Dick ◽  
E. Mánus Cunningham ◽  
Mathieu Lundy ◽  
Ewen Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Demographic Data ◽  
Irish Sea ◽  
Natural Phenomenon ◽  
Nephrops Norvegicus ◽  
North East ◽  
The North ◽  
Norway Lobster ◽  
The North Sea ◽  
Reproductive Cycles

Abstract The Norway lobster, Nephrops norvegicus, is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

Archipelagos and islands

2011 ◽  
Author(s):  
Robert Van de Noort
Keyword(s):  
North Sea ◽  
Coastal Wetland ◽  
Sand Dunes ◽  
Great Distance ◽  
North East ◽  
The North ◽  
Island Archaeology ◽  
The North Sea ◽  
Shallow Soils ◽  
Blackwater Estuary

The North Sea is not renowned for its islands, and much of the modern land–sea interface is sharp, especially along the coasts of Jutland, North and South Holland and much of England. Nevertheless, the North Sea does contain a surprisingly large number of islands and archipelagos, which can be presented with reference to a clear north–south divide. In the northern half of the North Sea, most islands are of hard rock with shallow soils, and their islandness is the result of ongoing glacio-isostatic uplift of previously drowned lands and sea-level rise. With the exception of the Shetland and Orkney archipelagos, few of these islands are found at a great distance from the mainland, and the majority of the countless islands, islets, and rock outcrops off the North Sea coasts of Norway, Sweden, Scotland, and north-east England can be found within a few miles of the mainland. In the southern half of the North Sea, the islands are mainly made up of sand and clay and, in their history if not today, were frequently sandbanks formed by the sea utilizing both marine and riverine sediments. Most of the islands of the Wadden Sea in Denmark, Germany, and Holland are sandbanks elevated by aeolian-formed sand dunes. Further south, the core of the large islands of Zeeland is principally formed of riverine sands and marine clays intercalated with peat, reflecting coastal wetland conditions at various times in the Post-glacial and Holocene (Vos and Van Heeringen 1997). As with Zeeland, the islands on the English side of the North Sea, such as Mersey Island in the Blackwater estuary and Foulness Island in Essex, have now been incorporated into the mainland. Only a few islands cannot be so simply classified:Helgoland in the German Bight, a Sherwood Sandstone stack of Triassic date, is the best known example. Island archaeology, as we have seen (chapter 2), has for many decades approached islands as environments that were relatively isolated from the wider world.

Sea-level related molluscan plankton events (Gastropoda, Euthecosomata) during the Rupelian (Early Oligocene) of the North Sea Basin

2004 ◽  
Vol 83 (3) ◽  
pp. 199-208
Author(s):  
K. Gürs ◽  
A.W. Janssen
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Short Term ◽  
The North ◽  
Early Oligocene ◽  
The North Sea

AbstractSpacio-temporal distribution patterns of North Sea Basin Early Oligocene (Rupelian) pteropoda (holoplanktonic gastropods: Mollusca, Gastropoda, Euthecosomata) are studied. These patterns indicate three short term invasions of a single pteropod species during the Rupelian. These invasions are indicated here as Clio blinkae Event, Praehyalocylis laxeannulata Event and Clio jacobae Event. The conspicuously short occurrences of the species, their abundances and some lithological features of the pteropod bearing strata lead to the conclusion that these plankton events are linked to sea level high-stands allowing currents from the worlds oceans to enter into the North Sea Basin.

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