Upper-mantle S-velocity structure of central and western South
... independent estimates of depth to the Mohorovic̆ić discontinuity, yielding model SA99. The S-velocity structure of SA99 reveals a highly heterogeneous upper mantle with a maximum peak to peak S-velocity difference of 1 km/s above 100 km. The heterogeneity seems to be correlated with tectonic and ge ...
... independent estimates of depth to the Mohorovic̆ić discontinuity, yielding model SA99. The S-velocity structure of SA99 reveals a highly heterogeneous upper mantle with a maximum peak to peak S-velocity difference of 1 km/s above 100 km. The heterogeneity seems to be correlated with tectonic and ge ...
Mechanical (de-)coupling of the lithosphere in the Valencia Trough
... horizontal decoupling. Other authors have studied decoupling as the possibility of two layers to move independently of each other in the vertical sense (e.g. [23], see Fig. 1c). In this view, stresses exerted by the bounding brittle layers would not be transmitted vertically. In contrast, they would ...
... horizontal decoupling. Other authors have studied decoupling as the possibility of two layers to move independently of each other in the vertical sense (e.g. [23], see Fig. 1c). In this view, stresses exerted by the bounding brittle layers would not be transmitted vertically. In contrast, they would ...
Nitrogen isotopes in bulk marine sediment: linking seafloor
... The δ 15 N of marine organic matter exported from the surface is equal to the isotopic composition of the nitrogen substrate supplied to the surface. A small fraction of this nitrogen is provided by local N2 fixation or atmospheric deposition, but the majority is supplied by upward transport from th ...
... The δ 15 N of marine organic matter exported from the surface is equal to the isotopic composition of the nitrogen substrate supplied to the surface. A small fraction of this nitrogen is provided by local N2 fixation or atmospheric deposition, but the majority is supplied by upward transport from th ...
An Iceland hotspot saga
... varying in ages from 5–200 Ma (Steinberger, 2000). Hotspot proliferation has been criticised. The deep plume hotspot-source hypothesis The Canadian geoscientist J. Tuzo Wilson (1908– 1993) first proposed in a number of articles (e.g. Wilson, 1963) that a hotspot source is deep in the mantle and prob ...
... varying in ages from 5–200 Ma (Steinberger, 2000). Hotspot proliferation has been criticised. The deep plume hotspot-source hypothesis The Canadian geoscientist J. Tuzo Wilson (1908– 1993) first proposed in a number of articles (e.g. Wilson, 1963) that a hotspot source is deep in the mantle and prob ...
Physical Oceanographic Assessment of the Nautilus EIS for the
... that upwelling currents would quickly sweep the dissolved fraction up into surface waters. Despite these plots indicating worrying risks to local communities, they were presented without analysis – in fact, without comment. The Nautilus EIS shows much the same pattern. In fact, the same company (Cof ...
... that upwelling currents would quickly sweep the dissolved fraction up into surface waters. Despite these plots indicating worrying risks to local communities, they were presented without analysis – in fact, without comment. The Nautilus EIS shows much the same pattern. In fact, the same company (Cof ...
Annual (interim) report. Reporting Period
... the Jamboree in view of the forthcoming phase and calls. More specifically, it has to be made clear that there is a gap between taxonomic lists resulting from a field observations and habitat classes. When survey maps are made, these lists are as best as possible translated into a level 5 or 6 Eunis ...
... the Jamboree in view of the forthcoming phase and calls. More specifically, it has to be made clear that there is a gap between taxonomic lists resulting from a field observations and habitat classes. When survey maps are made, these lists are as best as possible translated into a level 5 or 6 Eunis ...
Flow and melting of a heterogeneous mantle
... each lithology as labeled with their respective mass fraction in the mantle, / i. For EM and DM, values assumed for K D , D C*sol/liq, DH Afus, TAfus (variables are defined by [15]), are 0.25, 0.02, 10 kJ/mol, and 1336 8C, respectively [15]. For EM, assumed proportions for major component A (defined ...
... each lithology as labeled with their respective mass fraction in the mantle, / i. For EM and DM, values assumed for K D , D C*sol/liq, DH Afus, TAfus (variables are defined by [15]), are 0.25, 0.02, 10 kJ/mol, and 1336 8C, respectively [15]. For EM, assumed proportions for major component A (defined ...
Seismic evidence for subduction-transported water in the lower mantle
... Heijst, 2000]. Whether slabs penetrate to the core-mantle boundary or founder within the lower mantle, subduction clearly transports large volumes of material down into the lower mantle. Recent mineral physics work suggests that significant volumes of water may also be transported into the lower man ...
... Heijst, 2000]. Whether slabs penetrate to the core-mantle boundary or founder within the lower mantle, subduction clearly transports large volumes of material down into the lower mantle. Recent mineral physics work suggests that significant volumes of water may also be transported into the lower man ...
O ceanography THE OffICIAL MAGAzINE Of THE OCEANOGRAPHY SOCIETY
... population maintenance, colonization of new vents, and recolonization of disturbed vents. Historically, studying larvae has been challenging, especially in the deep sea. Advances in the last decade in larval culturing technologies and more integrated, interdisciplinary time-series observations are p ...
... population maintenance, colonization of new vents, and recolonization of disturbed vents. Historically, studying larvae has been challenging, especially in the deep sea. Advances in the last decade in larval culturing technologies and more integrated, interdisciplinary time-series observations are p ...
Rain ratio variation in the Tropical Ocean
... for preservation and (2) calculating organic carbon fluxes with multiple algorithms that depend in varying degrees on ballasting. We find that organic carbon flux estimates from algorithms with and without a ballasting function produce results different from one another. Sediment accumulation rates for ...
... for preservation and (2) calculating organic carbon fluxes with multiple algorithms that depend in varying degrees on ballasting. We find that organic carbon flux estimates from algorithms with and without a ballasting function produce results different from one another. Sediment accumulation rates for ...
From rifting to oceanic spreading in the Gulf of Aden: a synthesis
... Oligocene, 34–33 Ma ago, rifting started to localise along the future area of continental breakup. Initially guided by the inherited basins, continental rifting then occurred synchronously over the entire gulf before becoming localised on the northern and southern borders of the inherited grabens, i ...
... Oligocene, 34–33 Ma ago, rifting started to localise along the future area of continental breakup. Initially guided by the inherited basins, continental rifting then occurred synchronously over the entire gulf before becoming localised on the northern and southern borders of the inherited grabens, i ...
Subduction versus accretion of intra
... subduction/deformation of the continental lithosphere (continent^continent collision). Oceanic subduction typically results in the formation of magmatic arcs. Therefore, collisional mountain belts should normally contain remnants of the arcs. However, such remnants are less systematically found than ...
... subduction/deformation of the continental lithosphere (continent^continent collision). Oceanic subduction typically results in the formation of magmatic arcs. Therefore, collisional mountain belts should normally contain remnants of the arcs. However, such remnants are less systematically found than ...
59 4. DESCRIPTION OF STUDY AREA 4.1. Physiography and
... The age and orientation of the predominantly ENE to NE trending dyke swarms and associated aeromagnetic lineaments coincide with the 2 700 million years Ventersdorp rift structures, but also include similar NE trending Karoo-age dolerite dykes (Uken and Watkeys, 1997). During this period the northea ...
... The age and orientation of the predominantly ENE to NE trending dyke swarms and associated aeromagnetic lineaments coincide with the 2 700 million years Ventersdorp rift structures, but also include similar NE trending Karoo-age dolerite dykes (Uken and Watkeys, 1997). During this period the northea ...
Microbiology of seaMouNts
... associated with seamounts. The volcanically active portion of these undersea mountains hosts a remarkably diverse range of unusual microbial habitats, from black smokers rich in sulfur to cooler, diffuse, iron-rich hydrothermal vents. As such, seamounts potentially represent hotspots of microbial di ...
... associated with seamounts. The volcanically active portion of these undersea mountains hosts a remarkably diverse range of unusual microbial habitats, from black smokers rich in sulfur to cooler, diffuse, iron-rich hydrothermal vents. As such, seamounts potentially represent hotspots of microbial di ...
4.4. Phytoplankton and primary productivity off Northwest Africa The
... euphotic zone, generally defined as the depth where light reaches 1% of its surface value and where photosynthesis occurs. The depth of the euphotic layer varies from less than 10 m in dense or turbid coastal waters to about 80 m in very oligotrophic waters, as those of the tropica ...
... euphotic zone, generally defined as the depth where light reaches 1% of its surface value and where photosynthesis occurs. The depth of the euphotic layer varies from less than 10 m in dense or turbid coastal waters to about 80 m in very oligotrophic waters, as those of the tropica ...
Plate boundary deformation between the Pacific and North America
... One of the consequences of plate tectonics is that a spreading ridge will eventually approach a subduction zone. The problem whether the possible break-up of the approaching ridge will lead to the development of independent micro-plates, or not, is still unresolved. Some 4 million years ago the inte ...
... One of the consequences of plate tectonics is that a spreading ridge will eventually approach a subduction zone. The problem whether the possible break-up of the approaching ridge will lead to the development of independent micro-plates, or not, is still unresolved. Some 4 million years ago the inte ...
A global-scale plate reorganization event at 105−100Ma
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
Relationship between bend‐faulting at trenches and intermediate
... intraslab seismicity from Vanuatu, Tonga and PeruChile subduction zones. In these studies, direct comparison with the actual fault pattern at the trench was not possible due to the lack of highresolution bathymetric maps of the incoming plate. The comparison of a large number of intraplate events fr ...
... intraslab seismicity from Vanuatu, Tonga and PeruChile subduction zones. In these studies, direct comparison with the actual fault pattern at the trench was not possible due to the lack of highresolution bathymetric maps of the incoming plate. The comparison of a large number of intraplate events fr ...
Benthic Exchange and Biogeochemical Cycling in Permeable
... et al. 1996). In this review, we therefore define permeable sediments as those with a permeability greater than 10−12 m2 ; when this threshold is reached, interfacial solute fluxes deviate significantly from those associated with molecular diffusive transport, and advective pore-water flows dominate exc ...
... et al. 1996). In this review, we therefore define permeable sediments as those with a permeability greater than 10−12 m2 ; when this threshold is reached, interfacial solute fluxes deviate significantly from those associated with molecular diffusive transport, and advective pore-water flows dominate exc ...
Lithosphere and Asthenosphere
... The definition of the lithosphere is based on how Earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle. Since it is rigid and brittle, when stresses act on the lithosphere, it breaks. This is what we experience as an earthquake. Although we sometimes refe ...
... The definition of the lithosphere is based on how Earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle. Since it is rigid and brittle, when stresses act on the lithosphere, it breaks. This is what we experience as an earthquake. Although we sometimes refe ...
one ocean final.indd
... meaningful changes to the way in which they view our natural resource base, particularly water. • Ocean Explorer is an exploration of the ocean using leading-edge Google Ocean technology. This component also allows students to collaborate with friends to uncover the ocean’s mysteries. • Time Machine ...
... meaningful changes to the way in which they view our natural resource base, particularly water. • Ocean Explorer is an exploration of the ocean using leading-edge Google Ocean technology. This component also allows students to collaborate with friends to uncover the ocean’s mysteries. • Time Machine ...
Redalyc.Long-term evolution of subduction zones and the
... subduction system along the western North America continental margin (McKenzie and Morgan, 1969; Atwater, 1970, 1989). The magmatism covers a zone more than 1000 km wide. An eastward shift of igneous activity (Lindgren, 1915) took place during Late Mesozoic to Early Cenozoic times (Lipman et al., 1 ...
... subduction system along the western North America continental margin (McKenzie and Morgan, 1969; Atwater, 1970, 1989). The magmatism covers a zone more than 1000 km wide. An eastward shift of igneous activity (Lindgren, 1915) took place during Late Mesozoic to Early Cenozoic times (Lipman et al., 1 ...
3. Strategy for an Observational Network for Ocean Acidification
... surface waters in the global ocean are currently super-saturated (e.g., values of 2-4 for aragonite and 4-6 for calcite), because many organisms have optimal carbonate precipitation rates at these or higher saturation states. Photosynthesis by marine photosynthetic organisms (Reaction 4) consumes ...
... surface waters in the global ocean are currently super-saturated (e.g., values of 2-4 for aragonite and 4-6 for calcite), because many organisms have optimal carbonate precipitation rates at these or higher saturation states. Photosynthesis by marine photosynthetic organisms (Reaction 4) consumes ...
PHYTOPLANKTON, ZOOPLANKTON, MICRONEKTON, AND
... collected data from LTOP and process studies--will provide a comparison to similar observations collected previously and provide a baseline for future data collections and comparisons. The GLOBEC principal investigators have identified a number of historical data sets that should be reevaluated and/ ...
... collected data from LTOP and process studies--will provide a comparison to similar observations collected previously and provide a baseline for future data collections and comparisons. The GLOBEC principal investigators have identified a number of historical data sets that should be reevaluated and/ ...
Analogue modelling of continental collision: Influence of plate
... addition, the shear zone is maintained by far field stresses generated by the attachment of an earlier subducted oceanic slab (e.g. Toussaint et al., 2004a). Far field stresses within the model generated by the moving wall are mostly accommodated within the much thicker ductile layers. Therefore, we l ...
... addition, the shear zone is maintained by far field stresses generated by the attachment of an earlier subducted oceanic slab (e.g. Toussaint et al., 2004a). Far field stresses within the model generated by the moving wall are mostly accommodated within the much thicker ductile layers. Therefore, we l ...
Abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone.Abyssal plains were not recognized as distinct physiographic features of the sea floor until the late 1940s and, until very recently, none had been studied on a systematic basis. They are poorly preserved in the sedimentary record, because they tend to be consumed by the subduction process. The creation of the abyssal plain is the end result of spreading of the seafloor (plate tectonics) and melting of the lower oceanic crust. Magma rises from above the asthenosphere (a layer of the upper mantle) and as this basaltic material reaches the surface at mid-ocean ridges it forms new oceanic crust. This is constantly pulled sideways by spreading of the seafloor. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment is composed chiefly of pelagic sediments. Metallic nodules are common in some areas of the plains, with varying concentrations of metals, including manganese, iron, nickel, cobalt, and copper. These nodules may provide a significant resource for future mining ventures.Owing in part to their vast size, abyssal plains are currently believed to be a major reservoir of biodiversity. The abyss also exerts significant influence upon ocean carbon cycling, dissolution of calcium carbonate, and atmospheric CO2 concentrations over timescales of 100–1000 years. The structure and function of abyssal ecosystems are strongly influenced by the rate of flux of food to the seafloor and the composition of the material that settles. Factors such as climate change, fishing practices, and ocean fertilization are expected to have a substantial effect on patterns of primary production in the euphotic zone. This will undoubtedly impact the flux of organic material to the abyss in a similar manner and thus have a profound effect on the structure, function and diversity of abyssal ecosystems.