Parsons and J. Pavlenkova and S. Rundshau 70 Pearson, C. Emeleus, and S. London Richardson, J. Smallwood, R. White, et al. Riisager, P. Riisager, and A. Roberts, J. Backman, J. Morton, et al. DSDP 81 , Rognvaldsson, G. Gudmundsson, K. Agustsson, et al.
Papers presented at the Reykjavic, , pp. Smallwood and R.
Sinton and R. Saunders A. ODP Sci. Results , — Storey, R. Duncan, H. Larsen, et al. Duncan, A. Pedersen, et al. Stuart, R. Ellam, P. Harrop, et al. Talwani, C. Windisch, and M. Taylor, M. Thirwall, B. Murton, et al. Tegner, R. Duncan, S. Bernstein, et al. Vogt, R. Perry, R. Feden, et al. Plenum Press, New York, , pp. Weir, R. White, B. Brandsdottir, et al. Soc , — White and D. Wolfe and I. Bjarnason, VanDecar J.
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Kononov 1 A. Advertisement Hide. Genesis of the lithosphere of the Iceland region North Atlantic according to geophysical data. Authors Authors and affiliations E. Verzhbitskii M. Kononov A. Byakov O. Marine Geology First Online: 03 May This process is experimental and the keywords may be updated as the learning algorithm improves. This is a preview of subscription content, log in to check access.
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Lobkovskii, M. Kononov, et al. Genshaft and A. Karslou and D. Mirlin, V. Melikhov, and T. Belousov and G. Udintsev Nauka, Moscow, , pp. Mirlin, K. Popov, and D. Polyak and Ya. Polyak, V. Kononov, and M.
Rift Zone of the Reykjanes Ridge , Ed. Lisitsin and L. Zonenshain Nauka, Moscow, [in Russian]. Khain and P. A Nauchnyi Mir, Moscow, , pp. Beblo, A. Bjornsson, K. Arnason, et al. Bjarnason, W. Menke, O. Flovens, et al. Carlson and H. CrossRef Google Scholar. Chambers and M. Clift, A. Carter, and A.
Dickin and N. MacDougall J. Continental Flood Basalt. Hingham, Mass. Eldholm and K. Eldholm, J. Thiede, E. We attribute this. Boat Basin , U. All of the waters of Camp Pendleton Boat Detection of baleen whales on an ocean -bottom seismometer array in the Lau Basin.
Long-term deployment of ocean -bottom seismometer arrays provides a unique opportunity for identifying and tracking whales in a manner not usually possible in biological studies. The calls are distinct to individual species and even geographical groups among species, and are thought to serve a variety of purposes. Distinct repeating calls can be automatically identified using matched-filter processing, and whales can be located in a manner similar to that of earthquakes. Many baleen whale species are endangered, and little is known about their geographic distribution, population dynamics, and basic behaviors.
The Lau back-arc basin , a tectonically active, elongated basin bounded by volcanic shallows, lies in the southwestern Pacific Ocean between Fiji and Tonga. Although whales are known to exist around Fiji and Tonga, little is understood about the population dynamics and migration patterns throughout the basin. Twenty-nine broadband ocean -bottom seismometers deployed in the basin recorded data for approximately ten months during the years To date, four species of whales have been identified in the data: Blue one call type , Humpback two call types, including long-lasting 'songs' , Bryde's one call type , and Fin whales three call types.
Three as-yet-unknown call types have also been identified. After the calls were identified, idealized spectrograms of the known calls were matched against the entire data set using an auto-detection algorithm. The auto-detection output provides the number of calls and times of year when each call type was recorded.
Based on the results, whales migrate seasonally through the basin with some overlapping of species. Initial results also indicate that different species of whales are more common in some parts of the basin than. Phanerozoic stratigraphy of Northwind Ridge, magnetic anomalies in the Canada Basin , and the geometry and timing of rifting in the Amerasia Basin , Arctic Ocean.
Grantz, A. Cores from Northwind Ridge, a high-standing continental fragment in the Chukchi borderland of the oceanic Amerasia basin , Arctic Ocean , contain representatives of every Phanerozoic system except the Silurian and Devonian systems. Cambrian and Ordovician shallow-water marine carbonates in Northwind Ridge are similar to basement rocks beneath the Sverdrup basin of the Canadian Arctic Archipelago.
Upper Mississippian? These resemblances indicate that Triassic and older strata in southern Northwind Ridge were attached to both Arctic Canada and Arctic Alaska prior to the rifting that created the Amerasia basin. Late Jurassic marine lutite in Northwind Ridge was structurally isolated from coeval strata in the Sverdrup and Arctic Alaska basins by rift shoulder and grabens, and is interpreted to be a riftogenic deposit.
This lutite may be the oldest deposit in the Canada basin. A cape of late Cenomanian or Turonian rhyodacite air-fall ash that lacks terrigenous material shows that Northwind Ridge was structurally isolated from the adjacent continental margins by earliest Late Cretaceous time. Closing Amerasia basin by conjoining seafloor magnetic anomalies beneath the Canada basin or by uniting the pre-Jurassic strata of Northwind Ridge with kindred sections in the Sverdrup basin and Hanna trough yield simular tectonic reconstructions. Together with the orientation and age of rift-marine structures, these data suggest that: 1 prior to opening of the Amerasia basin , both northern Alaska and continental ridges of the Chukchi borderland were part of North America, 2 the extension that created the Amerasia basin formed rift-margin graben beginning in Early Jurassic time and new oceanic crust probably beginning in Late Jurassic or early Neocomian time.
Reconstruction of the Amerasia basin on the. The North-eastern Indian Ocean has recently received a renewed interest. The disastrous earthquakes and tsunamis of Dec. The Ninetyeast Ridge, a long submarine ridge which extends NS on more than km, has been the focus of a recent cruise aiming to study the interaction of a hotspot with the oceanic lithosphere and spreading centres.
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Both the study of the seismogenic zone under Sumatra and the Ninetyeast Ridge formation require accurate determination of the age and structure of the oceanic lithosphere in the Wharton and Central Indian Basins. First we delineate tectonic elements such as the Sunda Trench, the Ninetyeast Ridge, and the fracture zones of the Wharton and Central Indian basins from a recent version of the free-air gravity anomaly deduced from satellite altimetry and available multibeam bathymetric data. We use all available magnetic data to identify magnetic anomalies and depict seafloor spreading isochrons in order to build a tectonic map of the Wharton Basin.
To do so, we apply the analytic signal method to unambiguously determine the location of the magnetic picks. The new tectonic map shows more refinements than previous ones, as expected from a larger data set. The fossil ridge in the Wharton Basin is clearly defined; spreading ceased at anomaly 18 young Symmetric anomalies are observed on both flanks of the fossil ridge up to anomaly 24 54 Ma , preceded by a slight reorganization of the spreading compartments between anomalies 28 and 25 64 - 56 Ma and a more stable phase of spreading between anomalies 34 and 29 83 - 64 Ma.
Generations of spreading basins and stages of breakdown of Wegener's Pangea in the geodynamic evolution of the Arctic Ocean. This study made it possible to indentify three temporally and spatially isolated generations of spreading basins : Late Jurassic-Early Cretaceous, Late Cretaceous-Early Cenozoic, and Cenozoic.
The first generation is determined by the formation, evolution, and extinction of the spreading center in the Canada Basin as a tectonic element of the Amerasia Basin. The second generation is connected to the development of the Labrador-Baffin-Makarov spreading branch that ceased to function in the Eocene. The third generation pertains to the formation of the spreading system of interrelated ultraslow Mohna, Knipovich, and Gakkel mid- ocean ridges that has functioned until now in the Norwegian-Greenland and Eurasia basins.
The interpretation of the available geological and geophysical data shows that after the formation of the Canada Basin , the Arctic region escaped the geodynamic influence of the Paleopacific, characterized by spreading, subduction, formation of backarc basins , collision-related processes, etc. The origination of the Makarov Basin marks the onset of the oceanic regime characteristic of the North Atlantic intercontinental rifting, slow and ultraslow spreading, separation of continental blocks microcontinents , extinction of spreading centers of primary basins , spreading jumps, formation of young spreading ridges and centers, etc.
The aforesaid indicates that the Arctic Ocean is in fact a hybrid basin or, in other words, a composite heterogeneous ocean in respect to its architectonics. The Arctic Ocean was formed as a result of spatial juxtaposition of two geodynamic systems different in age and geodynamic style: the Paleopacific. A tale of two basins : An integrated physical and biological perspective of the deep Arctic Ocean. This review paper integrates the current knowledge, based on available literature, on the physical and biological conditions of the Amerasian and Eurasian basins AB, EB of the deep Arctic Ocean AO in a comparative fashion.
The present day Holocene AO is a mediterranean sea that is roughly half continental shelf and half basin and ridge complex. Even more recently it is roughly two thirds seasonally and one third perennially ice-covered, thus now exposing a portion of basin waters to sunlight and wind. Basin boundaries and submarine ridges steer circulation pathways in overlying waters and limit free exchange in deeper waters. Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin.
Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark Galeocerdo cuvier population structure off the oceanic insular system of Fernando de Noronha FEN and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry.
A total of 25 sharks measuring cm in total length TL were sampled. Most sharks were likely immature females ranging between and cm TL, with few individuals oceanic basin , one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than days at liberty.
The present results suggest that young tiger sharks measuring oceanic habitats from the western South Atlantic Ocean , which agrees with a previously-hypothesized ontogenetic habitat shift from coastal to oceanic habitats experienced by juveniles of this species in this region. In addition. A total of 25 sharks measuring — cm in total length TL were sampled.
Stable isotope analyses of feather amino acids identify penguin migration strategies at ocean basin scales. Identifying the at-sea distribution of wide-ranging marine predators is critical to understanding their ecology. Advances in electronic tracking devices and intrinsic biogeochemical markers have greatly improved our ability to track animal movements on ocean -wide scales.
Here, we show that, in combination with direct tracking, stable carbon isotope analysis of essential amino acids in tail feathers provides the ability to track the movement patterns of two, wide-ranging penguin species over ocean basin scales. In addition, we use this isotopic approach across multiple breeding colonies in the Scotia Arc to evaluate migration trends at a regional scale that would be logistically challenging using direct tracking alone. Morphology and chemical composition of glass shards and associated microtektites have been used to trace their provenance.
Polyakov, Igor V. Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of the intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin.
The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin. Ancient drainage basin of the Tharsis region, Mars: Potential source for outflow channel systems and putative oceans or paleolakes.
Dohm, J. Large topographic highs formed the margin of the gigantic drainage basin. Subsequently, lavas, sediments, and volatiles partly infilled the basin , resulting in an enormous and productive regional aquifer. The stacked sequences of water-bearing strata were then deformed locally and, in places, exposed by magmatic-driven uplifts, tectonic deformation, and erosion.
Copyright by the American Geophysical Union. A comparison of the South China Sea and Canada Basin : two small marginal ocean basins with hyper-extended margins and central zones of sea-floor spreading. Both the South China Sea and Canada Basin preserve oceanic spreading centres and adjacent passive continental margins characterized by broad COT zones with hyper-extended continental crust.
We have investigated the nature of strain accommodation in the regions immediately adjacent to the oceanic spreading centres in these two basins using 2-D backstripping subsidence reconstructions, coupled with forward modelling constrained by estimates of upper crustal extensional faulting. Modelling is better constrained in the South China Sea but our results for the Beaufort Sea are analogous. A weak lower crust in the presence of high heat flow is suggested for both basins.
Extension in the COT may continue even after sea-floor spreading has ceased. A zonally averaged, three- basin ocean circulation model for climate studies. A two-dimensional, three- basin ocean model suitable for long-term climate studies is developed. The model is based on the zonally averaged form of the primitive equations written in spherical coordinates.
The east-west density difference which arises upon averaging the momentum equations is taken to be proportional to the meridional density gradient. Lateral exchanges of heat and salt between the basins are explicitly resolved. Moreover, the model includes bottom topography and has representations of the Arctic Ocean and of the Weddell and Ross seas. Superimposed on this thermohaline circulation are vigorous wind-driven cells in the upper thermocline.
The simulated temperature and salinity fields and the computed meridional heat transport compare reasonably well with the observational estimates. When mixed boundary conditions i. The conveyor-belt circulation always results at this stage. A series of perturbation experiments illustrates the ability of the model to reproduce different steady-state circulations under mixed boundary conditions.
Finally, the model sensitivity to various factors is examined. This sensitivity study reveals that the bottom topography and the presence of a submarine meridional ridge in the zone of the Drake Passage play a crucial role in determining the properties of the model bottom-water masses.
The importance of the seasonality of the surface forcing is also stressed. Do manganese nodules grow or dissolve after burial? Results from the Central Indian Ocean Basin. Buried nodule size decreases with core depth and this distribution appears to be similar to the phenomenon of "Brazil Nut Effect".
Buried nodules exhibit both smooth and rough surface textures and are ellipsoidal, elongated, rounded, sub rounded, irregular and polynucleated. Buried nodules from siliceous ooze suggest their formation under hydrogenetic, early digenetic and diagenetic processes whereas those from red clay are of hydrogenetic origin. REE are enriched more than 1. However, the mode of incorporation of REE into buried nodules from both sedimentary environments is by a single authigenic phase consisting of Fe-Ti-P.
Shale-normalized REE patterns and Ce anomalies suggest that nodules from siliceous ooze formed under more oxidizing conditions than those from red clay. Nodules buried at depths between 1. Chemical composition, surface texture and morphology of buried nodules are similar to those of surface nodules from the same basin. Furthermore, buried nodule compositions do not exhibit any distinct patterns within the core depth. Mesoscale dynamics in the Lofoten Basin - a sub-Arctic "hot spot" of oceanic variability.
A sub-Arctic "hot spot" of intense mesoscale variability is observed in the Lofoten Basin LB - a topographic depression with a maximum depth of about m, located in the Norwegian Sea. The standard deviation of sea surface height SSH , measured with satellite altimetry, reaches nearly 15 cm in the center of the basin Figure 1a.
The fact that surface drifter trajectories do not exhibit cyclonic circulation in the LB Figure 1b suggests that, at least in the upper ocean , satellite altimetry observes only the propagation of form without the corresponding transfer of mass. Linearly propagating wavelike disturbances that do not trap fluid inside are related to planetary or Rossby waves. Variations in topography may lead to the concentration of wave energy in certain regions or wave trapping.
The dispersion analysis suggests that the observed wavelike cyclonic propagation of SSH anomalies in the LB is the manifestation of baroclinic topographic Rossby waves, that we term "the basin waves" in order to distinguish them from the other types of topographic waves, such as shelf or trench waves. We identify two modes of basin waves in the LB: a di-pole mode and a quadri-pole mode. The wavelength of each mode is about km.
We show that the cyclonically rotating basin waves are responsible for the observed amplification of SSH variability in the LB. Because the baroclinic basin waves in the LB are probably associated with large vertical displacements of the thermocline and due to possible wave breaking events, they can play an important role in the mixing of the inflowing Atlantic Water with ambient water masses. Southern rim of Pacific Ocean basin : southern Andes to southern Alps. Between the southern Andes of Tierra del Fuego and the southern Alps of New Zealand lies the least accessible and geologically least explored part of the Pacific Ocean basin.
A joint United Kingdom-United States project was initiated in to elucidate the geologic history and structure of the Pacific margin of Antarctica from the Antarctic Peninsula to Pine Island Bay at approximately lone. The first season of this West Antarctic Tectonics Project was spent in the Ellsworth-Whitmore crustal block, and the second in the Thurston Island crustal block. A final geologic season will be spent in the Pensacola Mountains of the Transantarctic Range in The oxidation state of iron and manganese in polymetallic nodules from the Central Indian Ocean Basin. The study of oxidation states of iron Fe and manganese Mn in polymetallic nodules were carried out by means of X-ray photoelectron spectroscopic techniques.
Basin -scale estimates of oceanic primary production by remote sensing - The North Atlantic. The monthly averaged CZCS data for are used to estimate annual primary production at ocean basin scales in the North Atlantic. The principal supplementary data used were vertical profiles of chlorophyll and sets of parameters derived from photosynthesis-light experiments. Four different procedures were tested for calculation of primary production. The spectral model with nonuniform biomass was considered as the benchmark for comparison against the other three models.
The less complete models gave results that differed by as much as 50 percent from the benchmark. Vertically uniform models tended to underestimate primary production by about 20 percent compared to the nonuniform models. At horizontal scale, the differences between spectral and nonspectral models were negligible. The linear correlation between biomass and estimated production was poor outside the tropics, suggesting caution against the indiscriminate use of biomass as a proxy variable for primary production. The newfoundland basin - Ocean -continent boundary and Mesozoic seafloor spreading history.
It is pointed out that over the past 15 years there has been considerable progress in the refinement of predrift fits and seafloor spreading models of the North Atlantic. With the widespread acceptance of these basic models has come increasing interest in resolution of specific paleogeographic and kinematic problems. Two such problems are the initial position of Iberia with respect to North America and the geometry and chronology of early pre m.
From the examination of magnetic data in the Newfoundland Basin , the OCB east of the Grand Banks is defined as the seaward limit of the 'smooth' magnetic domain which characterizes the surrounding continental shelves. A substantial improvement in Iberia-North America paleographic reconstructions is achieved. Fate of copper complexes in hydrothermally altered deep-sea sediments from the Central Indian Ocean Basin.
The current study aims to understand the speciation and fate of Cu complexes in hydrothermally altered sediments from the Central Indian Ocean Basin and assess the probable impacts of deep-sea mining on speciation of Cu complexes and assess the Cu flux from this sediment to the water column in this area. This study suggests that most of the Cu was strongly associated with different binding sites in Fe-oxide phases of the hydrothermally altered sediments with stabilities higher than that of Cu-EDTA complexes.
The speciation of Cu indicates that hydrothermally influenced deep-sea sediments from Central Indian Ocean Basin may not significantly contribute to the global Cu flux. However, increasing lability of Cu-sediment complexes with increasing depth of sediment may increase bioavailability and Cu flux to the global ocean during deep-sea mining.
All rights reserved. Genesis of Central Indian Ocean basin seamounts: morphological, petrological, and geochemical evidence. We present the petrological investigation carried out of the seamounts located between water depths of and m in the Central Indian Ocean Basin CIOB. The seamounts have variable shapes conical and elongated and heights m. The basalts have a glassy veneer that forms the outer rind, while the holocrystalline interior shows variable textures.
The production of the seamounts may have involved a periodic tapping of a regularly replenished and shallow seated source melt. These basalts from the older seamounts of the CIOB are analogous to their present-day counterparts that form at the fast-spreading EPR and other locales in the world oceans. Impact of data assimilation on ocean current forecasts in the Angola Basin. The addition of drifters significantly improves Lagrangian predictability in comparison to the baseline case as well as the addition of either altimetry or OSCAR.
On average the assimilation of either altimetry or OSCAR with drifter velocities does not significantly improve Lagrangian predictability compared to the drifter assimilation alone, even degrading predictability in some cases. When the forecast current speed is large, it is more likely that the combination improves trajectory forecasts. Conversely, when the currents are weaker, it is more likely that the combination degrades the trajectory forecast. Gravity anomalies and associated tectonic features over the Indian Peninsular Shield and adjoining ocean basins.
A combined gravity map over the Indian Peninsular Shield IPS and adjoining oceans brings out well the inter-relationships between the older tectonic features of the continent and the adjoining younger oceanic features. The Simple Bouguer anomaly map shows consistent increase in gravity value from the continent to the deep ocean basins , which is attributed to isostatic compensation due to variations in the crustal thickness.
Large crustal thickness and trends of the gravity anomalies may suggest a transitional crust in the Bay of Bengal up to km from the east coast. The crustal thickness under the Laxmi ridge and east of it in the Arabian Sea is 20 and 14 km, respectively, with km thick Tertiary and Mesozoic sediments separated by a thin layer of Deccan Trap.
The crustal density model in this part of the Arabian Sea east of Laxmi ridge and the structural trends similar to the Indian Peninsular Shield suggest a continent- ocean transitional crust COTC.
Ocean Basins - sea, depth, oceans, temperature, important, largest, system, marine, Pacific
The COTC may represent down dropped and submerged parts of the Indian crust evolved at the time of break-up along the west coast of India and passage of Reunion hotspot over India during late Cretaceous. The crustal model under this part also shows an underplated lower crust and a low density upper mantle, extending over the continent across the west coast of India, which appears to be related to the Deccan volcanism. The crustal thickness under the western Arabian Sea west of the Laxmi ridge. Sedimentology of cores recovered from the Canada Basin of the Arctic Ocean.
Edwards, B. Researchers from the United States and Canada are collaborating to understand the tectonic and sedimentary history of the Arctic Ocean between Canada and Alaska. As part of this on-going study, a joint US-Canadian ice breaker expedition operated in parts of the Canada Basin during August Occasional interruptions of the seismic data acquisition provided the ship time to collect gravity and piston cores at five sites-of-opportunity throughout the basin.
High-resolution multibeam bathymetry and chirp sub-bottom profiler data collected immediately prior to coring reveal the fine-scale morphology of each site. Core photographs, X-ray radiographs, and physical property data support the following descriptions. Two piston cores were collected from the Beaufort Sea continental margin in a region of known bottom simulating reflectors BSRs. Site 1 m water depth : This core recovered 5. Gas hydrate recovered in the core catcher combined with cracks and voids, methane and other hydrocarbon gasses, pyrite concretions, chemosynthetic clams, carbonate nodules, and soft carbonate masses indicate the likely upward migration of deep-seated fluids.
Site 2 m water depth : This core, positioned 40 km upslope from the gas hydrate core, recovered 3 m of gray sticky silty clay and clayey silt near the base of an erosional scarp. Some voids and fracturing are apparent but carbonate masses and pyrite concretions are absent. Site 3 m water depth : This core from the top of a seamount discovered in in the north-central part of the Canada Basin recovered 4. More than 3 m of dark brown to yellowish brown, massive interbedded silty clays with sands and matrix-supported gravels ice rafted debris [IRD] occur in abrupt contact with underlying reddish yellow to brownish yellow silty clay and.
We present images from a deep multi-channel seismic reflection survey acquired in over the oceanic lithosphere of the Wharton Basin offshore northern Sumatra, NW of Simeulue island. Similar dipping mantle events are imaged on the oceanic portion of another long-offset profile acquired in offshore central Sumatra south of Pagai island, which will also be presented. Such events are unlikely to be imaging artefacts of the 2D acquisition, such as out-of-plane energy originating from sharp, buried basement reliefs trending obliquely to the profile. Due to their geometry, they do not seem to be associated with plate bending at the trench outer-rise, which has a relatively modest expression at the seafloor and within the incoming sedimentary section north of the Simeulue elbow.
We propose that these deep-penetrating dipping reflectors are fossil fault planes formed due to compressive stresses at the beginning of the continent-continent collision between India and Eurasia, the early stages of which were responsible for the cessation of seafloor spreading at the Wharton ridge at ca 40 Ma. In , JSC Sevmorgeo with assistance of several research institutions of Federal Agency of Mineral Resources Rosnedra and Ministry of Defense carried out a unique set of offshore seismic and geological studies in the Mendeleev Rise area and adjacent areas of the Amerasia Basin.
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Two specially re-equipped icebreakers "Kapitan Dranitsin" and "Dixon" were used in this campaign. The main results of the expedition were km of multichannel seismic profiles both with long and short streamers m and m, respectively , km long refraction profile crossing Mendeleev Rise. Seismic acquisition with short streamers was accompanied by deployment of sonobuoys. Geological studies included deep-water drilling and sea-bottom sampling by dredge, gravity corer, grab and by specially equipped research submarine.
The newly acquired geological and geophysical data allowed for the following conclusions: 1. It is confirmed by direct tracking of some morphostructures, faults, gravity and magnetic anomalies from the shelf to deep-water highs. This area differs significantly from the Ellesmerian crustal domain located to the east including the Northwind Ridge, which coincides with inferred eastern boundary of the Mesozoides.
Western boundary of this block is inferred along the Spur of Geophysicists, which separates the Podvodnikov Basin into two unequal parts with different basement structure. From the south, southwest and west, the Central Arctic domain is. Inter- ocean exchange south of Africa takes place largely through the movement of Agulhas Rings into the Cape Basin. Recent observations have shown that the highly energetic flow field in this basin consists of anti-cyclonic rings as well as cyclonic eddies.
Very little is known of the characteristics of the cyclonic eddies. Using altimetric data, this study determines the location, frequency and seasonality of these cyclonic eddies their size, trajectories, life spans and their association with Agulhas Rings. Cyclonic eddies were seen to split, merge and link with other cyclonic eddies, where splitting events created child cyclonic eddies. The parent and child cyclonic eddies identified over a decade show that on average 11 parent and 17 child cyclonic eddies appear annually in AVISO merged absolute dynamic topography data along the continental slope.
Average translocation speeds are 2. A significant difference in lifespan for parent and child cyclonic eddies identified in the north and south region of the study area was detected. Topographical features appeared to affect the behaviour and lifespan of these deep cyclonic eddies.
Genesis of the lithosphere of the Iceland region (North Atlantic) according to geophysical data
The Arctic Ocean is generally assumed to be fairly quiescent when compared to many other oceans. The sea-ice cover, a strong halocline and a shallow, cold mixed-layer prevents much of the ocean to be affected by atmospheric conditions and properties of the ocean mixed-layer. In turn, the mixed-layer and the sea-ice is largely isolated from the warm layer of Atlantic origin below by the lower halocline.
Yet, the content of heat, freshwater and biologically important nutrients differs strongly between these different layers. Hence, it is crucial to be able to estimate vertical fluxes of salt, heat and nutrients to understand variability in the upper Arctic Ocean and the sea-ice, including the ecosystem. Yet, it is difficult to obtain direct flux measurements, and estimates are sparse. We present several sets of under-ice turbulent microstructure profiles in the Eurasian and Makarov Basin of the Arctic Ocean from two expeditions, in Our results are presented against a background of the anomalously warm atmospheric conditions during summer followed by unusually low temperatures in September.
Genesis of the lithosphere of the Iceland region (North Atlantic) according to geophysical data
We found highest levels of dissipation near the Eurasian continental slope and smaller peaks in the profiles where Bering Sea Summer Water sBSW lead to additional stratification within the upper halocline in the Makarov Basin. The elevated levels of dissipation associated with sBSW and the base of the mixed-layer were associated with the relatively low levels of vertical eddy diffusivity. We discuss these findings in the light of the anomalous conditions in the upper ocean , sea-ice and the atmosphere during and present estimates of vertical fluxes of heat, salt and other dissolved substances measured in water samples.
Identifying the cause of the dramatic correlation between atmospheric CO2 concentrations and past climate variability has been one of the principal goals of paleoclimate research over the past quarter century. Several plausible mechanisms have been proposed, and each has been rejected as being incapable by itself of accounting for the full range 80 to ppm of glacial to interglacial variability of atmospheric CO2 concentration. Consequently, recent studies have focused on scenarios by which a combination of mechanisms work synergistically to account for the full range of CO2 variability.
We will present evidence from equatorial Pacific sediment cores that increased strength of the ocean 's biological pump was primarily responsible for drawdown of atmospheric CO2 during the early stages of glaciation, and that increased ocean alkalinity or, more specifically, an increase in the ocean carbonate ion concentration led to a further reduction of atmospheric CO2 during maximum glaciation. Increased strength of the biological pump is manifest as increasing differences between the carbon isotope composition of planktonic and benthic foraminifera during early stages of glaciation, as predicted a quarter century ago in classic works by Broecker and by Shackleton.
Increased carbonate ion concentration is manifest by increased preservation and burial of calcium carbonate in deep equatorial Pacific sediments. The carbon isotope record is noisy, but the pattern is repeated over each of the past three glacial cycles, lending confidence to its reliability. Increased preservation and burial of CaCO3 occurred each time the oxygen isotope composition of benthic foraminifera rose above a threshold value corresponding to a sea level lowering of roughly 70 m below present.