scholarly journals Pliocene - Middle Pleistocene biostratigraphy in the Central Danish North Sea wells E-1, P-1 and TWB-12

1995 ◽  
Vol 13 ◽  
pp. 1-28
Author(s):  
Anette Mønsted Pedersen

Six foraminiferal assemblage zones and 6 subzones have been identified in the boreholes TWB-12, P-1 and E-1. The zones cover the interval from the Pliocene to the Middle Pleistocene. In TWB-12 and E-1 the Pliocene /Pleistocene boundary is placed at the first common occurrence of the species Elphidium oregonense. This species was not found in P-1, and the boundary is here, tentatively, placed above the last local occurrence of Cibicides grossus. The palaeoecological variations indicated by the Pleistocene assemblages, suggest several oscillations both in water depth and in palaeotemperature. A cold, shallow water interval with Elphidium oregonense at the Pliocene/Pleistocene boundary is followed by a Early Pleistocene warm, deep water interval with a high content of the genera Stainforthia and Bulimina. These deposits are probably from the warm Tiglian stage. The succeeding Early Pleistocene fauna! assemblages indicate a cold, upwards shallowing environment, and in this interval the arctic species Elphidiella gorbunovi often has a short ranged occurrence. The fauna! assemblages of the overlying deposits are characterized by the species Elphidium ustulatum and Elphidium albiumbilicatum, and indicates nearshore/ deltaic conditions. This part of the sequence probably includes the Early /Middle Pleistocene boundary. The uppermost assemblages in the examined sequence indicate arctic, shallow water conditions. They are, probably, of Saalian age, and are referred to Middle Pleistocene.

1995 ◽  
Vol 13 ◽  
pp. 1-56
Author(s):  
Anette Mønsted Pedersen

Pliocene and Pleistocene deposits from 66 boreholes from the central and northern North Sea have been examined for their content of benthic foraminifera. In this area the Pliocene/Pleistocene boundary is generally placed at the bottom or middle of the Elphidium oregonense Subzone or at the last local occurrence of Cibicides grossus. A detailed study of the temporal relationship between these two species in the western part of the Danish sector shows, that the last local occurrence of Cibicides grossus in this area is older than the Elphidium oregonense Subzone. On the basis of the results concerning the Lower Pleistocene an emendation of the foraminiferal biostratigraphy for this sub-series is proposed and related to previous work on the biostratigraphy and palaeogeography of the North Sea area. The investigation indicates the existence of two distinct new subzones within the Elphidiella hannai/Cassidulina teretis range: The oldest of the two new subzones is an Acme-zone with Buliminidae as the characteristic taxon, and it is named the Stainforthia/Bulimina Subzone. The depositional environment was a boreal shelf with a water depth presumed to exceed 100 m. Based on its stratigraphic position and enviromental indications the Subzone is referred to the Tiglian stage. The youngest of the two new subzones is a local Range-zone, defined by the presence of the arctic species Elphidiella gorbunovi, and it is named the Elphidiella gorbunovi Subzone. The depositional environment was an arctic shelf with a water depth of less than 50 m. The occurrence of Elphidiella gorbunovi in the central North Sea thus indicates a cold interval in either the Eburonian or the Menapian stage. Succeeding the Elphidiella gorbunovi Subzone, the foraminiferal fauna and the sediment indicate increasingly near-coastal environment and a warming of the climate.


1995 ◽  
Vol 12 ◽  
pp. 101-111
Author(s):  
Peter B Konradi

Cutting samples from two exploration wells, Cleo-1 and Kim-1, in the Central Trough area in the northwestern part of the Danish North Sea, have been investigated for foraminiferal content in the section above the prominent mid-Miocene event. Benthonic foraminifera have been used to produce a stratigraphic subdivision by reference to the standard NSB zonation of King. The NSB 12 to NSB 17 zones (Middle Miocene to Middle Pleistocene) have been identified above the event. These zones can be related to the paleo water depth zonation. Paleoenvironrnental reconstruction shows that sediments from the subject interval from Cleo-1 were deposited in a shallower situation than equivalent deposits in Kim-1. A conspicuous hiatus is identified in Cleo-1 at the Pliocene-Pleistocene boundary.


2020 ◽  
Author(s):  
Javier Gonzalez ◽  
Teresa Medialdea ◽  
Henrik Schiellerup ◽  
Irene Zananiri ◽  
Pedro Ferreira ◽  
...  

<p>The oceans and seas cover more than 70% of the planet, representing a promising new frontier for mineral resources exploration, and an enormous challenge for science and technology. Communities are demanding actions to address global climate change, and the necessary high- and green-technologies required for a transition from a carbon-based to green-energy-based world. The global ocean is at the core of these issues. The seabed mineral resources host the largest reserves on Earth for some critical metals like cobalt, tellurium, manganese, and the rare earth elements, critical for Industry. But seabed geology and ecosystems are widely unexplored, and new geological and environmental studies are required to address the impacts of potential mining activities. In addition, a regulatory framework for minerals extraction and marine spatial planning are necessary for seabed mining sector development.</p><p>The pan-European seas cover about 15 millions square kilometres in the Arctic and Atlantic oceans and the Mediterranean, Baltic, and Black seas, from shallow waters up to 6000 m water depth. Spanning a large diversity of environments and resource settings, including high and low temperature hydrothermal deposits, phosphorites, cobalt-rich ferromanganese crusts, and manganese nodules, deep-sea deposits are particularly attractive for their polymetallic nature with high contents of rare and critical metals. Moreover, shallow-water resources, like marine placer deposits, represent another source for many critical metals and gems. The GeoERA-MINDeSEA[1]  project is compiling data and genetic models for all these deposit types based on extensive studies, carried out previously, which include geophysical surveys, dredging stations, underwater photography and ROV surveys, and mineralogical, geochemical, and isotopic studies.</p><p>The preliminary MINDeSEA results show the potential of the pan-European seas for critical metals, and the enormous gaps of information covering vast marine sectors. More than 600 mineral occurrences are reported in the MINDeSEA database. Seamounts and banks in the Macaronesia sector (Portugal and Spain) and the Arctic ridges (Norway, Denmark, Iceland) show a high potential for Fe-Mn crusts, rich in energy-critical elements like Co but also Te, REEs, and Mn. Fe-Mn crusts are accompanied by phosphorites on the seafloor of continental shelves and slopes along the western continental margins. Seafloor polymetallic sulphides and metalliferous sediments precipitating from hot hydrothermal solutions and plumes are forming today in the Azores Islands (Portugal), the Arctic (Norway, Denmark) and, the Mediterranean volcanic arcs (Italy and Greece). They are among the most important marine resources for Cu, Zn, Ag, and Au. In addition, hydrothermal deposits may contain economic grades of Co, Sn, Ba, In, Bi, Te, Ga, and Ge. Placer deposits of chemically resistant and durable minerals have been discovered on shallow-water settings (<50 m water depth on estuaries, deltas, beaches) linked to the weathering of onshore rocks and ore deposits from the Variscan Belt (UK, France, Portugal, Spain). Finally, shallow-water concretions and nodules from the Arctic, Baltic, and Black Sea represent potential targets for metals exploration and environmental studies.</p><div><br><div> <p>[1] This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166</p> <p> </p> </div> </div>


1985 ◽  
Vol 24 (3) ◽  
pp. 295-306 ◽  
Author(s):  
Robert E. Nelson ◽  
L. David Carter

A 14-m-thick section of marine and nonmarine sediments of the Gubik Formation of northern Alaska, exposed in bluffs near Ocean Point on the Colville River, has been studied by means of pollen analysis. Pollen from the marine sediments, of probable late Pliocene age, records a boreal forest of spruce and birch with minor amounts of alder in the adjacent terrestrial vegetation. Pine and perhaps true fir were probably at or near their northern limit here, but hemlocks and hardwoods were absent. The suggested environment for the Arctic Slope during the time represented by the marine sediments is similar to that of present-day Anchorage. Pollen floras from the overlying fluvial strata, of early or middle Pleistocene age, record predominantly herbaceous taxa indicating tundra conditions probably more severe than those of the present day. These deposits were most likely contemporaneous with glacial conditions in the Brooks Range to the south. Pollen of woody taxa (spruce, alder, birch, heaths) is rare through most of the section, although birch and alder percentages similar to those found in modern river sediments indicate an interstadial or interglacial warming in midsection. Inland climates during glacial episodes may have been similar to those of the present Arctic coast.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  

AbstractThere is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith beds.


2016 ◽  
Vol 86 (3) ◽  
pp. 359-372 ◽  
Author(s):  
Pierluigi Pieruccini ◽  
Claudio Di Celma ◽  
Federico Di Rita ◽  
Donatella Magri ◽  
Giorgio Carnevale ◽  
...  

AbstractA 25 m-thick outcrop section exposed at Torre Mucchia, on the sea-cliff north of Ortona, eastern central Italy, comprises a rare Middle Pleistocene succession of shallow-water and paralic sediments along the western Adriatic Sea. An integrated study of the section, including facies and microfacies analyses, and characterization of paleobiological associations (mollusks, fishes, ostracods, foraminifers and pollen), enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition. The shallow-water deposits include a transgressive, deepening- and fining-upward shoreface to offshore-transition facies succession overlain by a regressive shoreface-foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea-level fall. This forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back-barrier lagoonal mudstones. The palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands (marl prairies). Following the sea-level rising trend, the freshwater marshes were abruptly replaced by a barrier-lagoon system that allowed deposition of the overlying mud-rich unit. Within these deposits, the faunal assemblages are consistent with a low-energy brackish environment characterized by a relatively high degree of confinement. The pollen record documents the development of open forest vegetation dominated by Pinus and accompanied by a number of mesophilous and thermophilous tree taxa, whose composition supports a tentative correlation with Marine Oxygen Isotope Stage 17. The new pollen record from Torre Mucchia improves our understanding of the vegetation development in the Italian Peninsula during the Middle Pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa.


2021 ◽  
Author(s):  
Li Zhang ◽  
Lei Xing ◽  
Mingyu Dong ◽  
Weimin Chen

Abstract Articulated pusher barge vessel is a short-distance transport vessel with good economic performance and practicability, which is widely used in the Yangtze River of China. In this present work, the resistance performance of articulated pusher barge vessel in deep water and shallow water was studied by model tests in the towing tank and basin of Shanghai Ship and Shipping Research Institute. During the experimental investigation, the articulated pusher barge vessel was divided into three parts: the pusher, the barge and the articulated pusher barge system. Firstly, the deep water resistance performance of the articulated pusher barge system, barge and the pusher at design draught T was studied, then the water depth h was adjusted, and the shallow water resistance at h/T = 2.0, 1.5 and 1.2 was tested and studied respectively, and the difference between deep water resistance and shallow water resistance at design draught were compared. The results of model tests and analysis show that: 1) in the study of deep water resistance, the total resistance of the barge was larger than that of the articulated pusher barge system. 2) for the barge, the shallow water resistance increases about 0.4–0.7 times at h/T = 2.0, 0.5–1.1 times at h/T = 1.5, and 0.7–2.3 times at h/T = 1.2. 3) for the pusher, the shallow water resistance increases about 1.0–0.4 times at h/T = 2.7, 1.2–0.9 times at h/T = 2.0, and 1.7–2.4 times at h/T = 1.6. 4) for the articulated pusher barge system, the shallow water resistance increases about 0.2–0.3 times at h/T = 2.0, 0.5–1.3 times at h/T = 1.5, and 1.0–3.5 times at h/T = 1.2. Furthermore, the water depth Froude number Frh in shallow water was compared with the changing trend of resistance in shallow water.


2011 ◽  
Vol 2 (2) ◽  
pp. 320-333
Author(s):  
F. Van den Abeele ◽  
J. Vande Voorde

The worldwide demand for energy, and in particular fossil fuels, keeps pushing the boundaries of offshoreengineering. Oil and gas majors are conducting their exploration and production activities in remotelocations and water depths exceeding 3000 meters. Such challenging conditions call for enhancedengineering techniques to cope with the risks of collapse, fatigue and pressure containment.On the other hand, offshore structures in shallow water depth (up to 100 meter) require a different anddedicated approach. Such structures are less prone to unstable collapse, but are often subjected to higherflow velocities, induced by both tides and waves. In this paper, numerical tools and utilities to study thestability of offshore structures in shallow water depth are reviewed, and three case studies are provided.First, the Coupled Eulerian Lagrangian (CEL) approach is demonstrated to combine the effects of fluid flowon the structural response of offshore structures. This approach is used to predict fluid flow aroundsubmersible platforms and jack-up rigs.Then, a Computational Fluid Dynamics (CFD) analysis is performed to calculate the turbulent Von Karmanstreet in the wake of subsea structures. At higher Reynolds numbers, this turbulent flow can give rise tovortex shedding and hence cyclic loading. Fluid structure interaction is applied to investigate the dynamicsof submarine risers, and evaluate the susceptibility of vortex induced vibrations.As a third case study, a hydrodynamic analysis is conducted to assess the combined effects of steadycurrent and oscillatory wave-induced flow on submerged structures. At the end of this paper, such ananalysis is performed to calculate drag, lift and inertia forces on partially buried subsea pipelines.


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