Plume mantle source heterogeneity through time: Insights from the
... et al., 1996, 1997a; Sinton et al., 1998; Hauff et al., 2000a, 2000b; Lapierre et al., 2000]. Picrites have been reported among the volcanic sequences in the CCOP, which are geochemically similar to the komatiitic lavas from Gorgona Island [Kerr et al., 1996]. Relatively immobile high field strength ...
... et al., 1996, 1997a; Sinton et al., 1998; Hauff et al., 2000a, 2000b; Lapierre et al., 2000]. Picrites have been reported among the volcanic sequences in the CCOP, which are geochemically similar to the komatiitic lavas from Gorgona Island [Kerr et al., 1996]. Relatively immobile high field strength ...
PDF (Chapter 11. Evolution of the Mantle)
... in the North and South Atlantic, where the cross section cuts across the Mid-Atlantic Ridge. Dashed lines are plate boundaries. Circles in upper panel are hotspots. (Model from Nataf and others, 1986.) ...
... in the North and South Atlantic, where the cross section cuts across the Mid-Atlantic Ridge. Dashed lines are plate boundaries. Circles in upper panel are hotspots. (Model from Nataf and others, 1986.) ...
Deep Sea Genetic Resources in the Context of the Convention on
... the theory of a desert-like environment. This was supported by the overwhelming wealth of different habitats like seamounts, deep-sea trenches, reef-forming corals, submarine canyons, cold seeps and pockmarks. Especially the discovery of deep-sea hydrothermal vents and their unique biological commun ...
... the theory of a desert-like environment. This was supported by the overwhelming wealth of different habitats like seamounts, deep-sea trenches, reef-forming corals, submarine canyons, cold seeps and pockmarks. Especially the discovery of deep-sea hydrothermal vents and their unique biological commun ...
Evolution of the middle and lower crust during the transition from
... and age of the zircon suggested that it represented a new generation of zircon growth at high temperatures. These data, and the dependence of crustal viscosity on temperature (e.g., Royden, 1996; Ellis et al., 1998), suggest that the lower crust was weak and flowed easily at the time extension initi ...
... and age of the zircon suggested that it represented a new generation of zircon growth at high temperatures. These data, and the dependence of crustal viscosity on temperature (e.g., Royden, 1996; Ellis et al., 1998), suggest that the lower crust was weak and flowed easily at the time extension initi ...
Outer slope faulting associated with the western Kuril and Japan
... (oceanward) and inner (landward) slopes of the trenches, from the crest of the outer swell to the mid-slope terrace of the inner slope where water depths are less than 3000 m. In all of these cruises, 3.5 kHz survey and/or single-channel seismic reflection profiles together with magnetic and gravity ...
... (oceanward) and inner (landward) slopes of the trenches, from the crest of the outer swell to the mid-slope terrace of the inner slope where water depths are less than 3000 m. In all of these cruises, 3.5 kHz survey and/or single-channel seismic reflection profiles together with magnetic and gravity ...
The Mean Age of Ocean Waters Inferred from Radiocarbon
... The focus of this work is the mass-weighted average age of ocean waters, or the ‘‘mean age,’’ which is here defined to be the mean of the pathway transit times from the mixed layer to the interior. The total amount of remineralized nutrient (or utilized oxygen) along a pathway is related to mean age ...
... The focus of this work is the mass-weighted average age of ocean waters, or the ‘‘mean age,’’ which is here defined to be the mean of the pathway transit times from the mixed layer to the interior. The total amount of remineralized nutrient (or utilized oxygen) along a pathway is related to mean age ...
Mantle structure and tectonic history of SE Asia
... Fig. 2. Tomographic slices through model UU-P07 (Amaru, 2007) at selected depths. Colours indicate the P-wave wave-speed anomalies relative to the radial reference model ak135 of Kennett et al. (1995). Notice that the limits of the wave-speed anomaly scale change with depth. This depth variation fol ...
... Fig. 2. Tomographic slices through model UU-P07 (Amaru, 2007) at selected depths. Colours indicate the P-wave wave-speed anomalies relative to the radial reference model ak135 of Kennett et al. (1995). Notice that the limits of the wave-speed anomaly scale change with depth. This depth variation fol ...
Dinitrogen fixation in aphotic oxygenated marine environments
... demonstrated a significant positive correlation between transparent exopolymeric particle (TEP) concentrations and N2 fixation rates. This suggests that sinking organic material and high carbon (C): nitrogen (N) micro-environments (such as TEP-based aggregates or marine snow) could support high hete ...
... demonstrated a significant positive correlation between transparent exopolymeric particle (TEP) concentrations and N2 fixation rates. This suggests that sinking organic material and high carbon (C): nitrogen (N) micro-environments (such as TEP-based aggregates or marine snow) could support high hete ...
Doglioni et al Mantle wedge asymmetries and geochemical
... body, where the melting feeding the magmatic arc can take place ...
... body, where the melting feeding the magmatic arc can take place ...
Modeling ocean acidification in the California Current System
... (CCS), one of the four major EBUS. A preindustrial simulation was conducted to study the natural carbon chemistry dynamics of this region. Results show that even before anthropogenic CO2 perturbed the carbon chemistry of the CCS, ∼84% of the benthic ecosystems on the continental shelf off northern a ...
... (CCS), one of the four major EBUS. A preindustrial simulation was conducted to study the natural carbon chemistry dynamics of this region. Results show that even before anthropogenic CO2 perturbed the carbon chemistry of the CCS, ∼84% of the benthic ecosystems on the continental shelf off northern a ...
as a PDF - Dipartimento di Scienze della Terra
... directed, apart central-north Japan, where the subduction system is reverting and the backarc basin shrinking. Moreover, the general observed rule is that the hinge moves away from the upper plate along W-directed subduction zones, whereas it regularly moves toward the upper plate along the opposite ...
... directed, apart central-north Japan, where the subduction system is reverting and the backarc basin shrinking. Moreover, the general observed rule is that the hinge moves away from the upper plate along W-directed subduction zones, whereas it regularly moves toward the upper plate along the opposite ...
`emplacement` of an ophiolite?
... lithosphere, which becomes an ophiolite when incorporated into continental margins through a complex process known as 'emplacement'. A fundamental problem of ophiolite emplacement is how dense oceanic crust becomes emplaced over less dense material(s) of continental margins or subduction-accretion s ...
... lithosphere, which becomes an ophiolite when incorporated into continental margins through a complex process known as 'emplacement'. A fundamental problem of ophiolite emplacement is how dense oceanic crust becomes emplaced over less dense material(s) of continental margins or subduction-accretion s ...
32. mineralogical and oxygen isotopic features of serpentinites
... and spinel. Amphiboles are undeformed except in narrow shear zones. Serpentinization cannot be linked with this high-temperature hydrous event. Like the serpentines drilled 100 km to the north at Hole 637A, Leg 103, the great majority of serpentines from the Leg 149 peridotites have δ18O values arou ...
... and spinel. Amphiboles are undeformed except in narrow shear zones. Serpentinization cannot be linked with this high-temperature hydrous event. Like the serpentines drilled 100 km to the north at Hole 637A, Leg 103, the great majority of serpentines from the Leg 149 peridotites have δ18O values arou ...
Stationary Eddies and the Zonal Asymmetry of Net Precipitation and
... that they all tend to have unphysical regions of net evaporation over land, trends associated with changes of observing system, and an overestimated magnitude of water cycling over oceans (affecting precipitation P and evaporation E but not P 2 E). We are interested in the large-scale balance of ter ...
... that they all tend to have unphysical regions of net evaporation over land, trends associated with changes of observing system, and an overestimated magnitude of water cycling over oceans (affecting precipitation P and evaporation E but not P 2 E). We are interested in the large-scale balance of ter ...
Mechanisms of crustal growth in large igneous
... asthenospheric mantle) because of the contamination of the melts by various crustal lithologies as illustrated by the Scottish Tertiary volcanics (e.g., Dickin et al., 1987, among others). Another approach to discuss the origin of the igneous activity is to establish the pattern of magma flow within ...
... asthenospheric mantle) because of the contamination of the melts by various crustal lithologies as illustrated by the Scottish Tertiary volcanics (e.g., Dickin et al., 1987, among others). Another approach to discuss the origin of the igneous activity is to establish the pattern of magma flow within ...
Nutrient gradients in the western North Atlantic Ocean
... detection limits of standard colorometric methods, except during periods of deep vertical mixing. Here we report the application of high-sensitivity analytical methodsFdeterminations of nitrate plus nitrite (N+N) by chemiluminescence and soluble reactive phosphorus (SRP) by the magnesium induced co- ...
... detection limits of standard colorometric methods, except during periods of deep vertical mixing. Here we report the application of high-sensitivity analytical methodsFdeterminations of nitrate plus nitrite (N+N) by chemiluminescence and soluble reactive phosphorus (SRP) by the magnesium induced co- ...
3.20 Trace Element and Isotopic Fluxes
... However, the extent of hydration in the uppermost mantle of subducting oceanic lithosphere is unclear (see Peacock, 2001; Kerrick, 2002). If such hydration occurs, it could profoundly increase the amount of H2O being subducted into the deep Earth, possibly causing flux melting of the slab (see Ranero ...
... However, the extent of hydration in the uppermost mantle of subducting oceanic lithosphere is unclear (see Peacock, 2001; Kerrick, 2002). If such hydration occurs, it could profoundly increase the amount of H2O being subducted into the deep Earth, possibly causing flux melting of the slab (see Ranero ...
Normalized rare earth elements in water
... although it is perhaps more appropriately used in the study of mafic and ultramafic rocks. Piper [20] proposed that the WSA represents perhaps a more appropriate standard in the examination of marine and non-marine sediments and surface waters, owing to similar relative concentrations of the REE in ...
... although it is perhaps more appropriately used in the study of mafic and ultramafic rocks. Piper [20] proposed that the WSA represents perhaps a more appropriate standard in the examination of marine and non-marine sediments and surface waters, owing to similar relative concentrations of the REE in ...
Fe isotopic compositions of modern seafloor hydrothermal
... 2.4 Factors controlling the Fe isotopic compositions of hydrothermal sulfides (1) Vent temperature The hydrothermal fluid temperature of black smoker chimneys in the high-temperature hydrothermal zones at 9 to 10°N on the East Pacific Rise exceeds 300°C. The hydrothermal fluid temperature in the lo ...
... 2.4 Factors controlling the Fe isotopic compositions of hydrothermal sulfides (1) Vent temperature The hydrothermal fluid temperature of black smoker chimneys in the high-temperature hydrothermal zones at 9 to 10°N on the East Pacific Rise exceeds 300°C. The hydrothermal fluid temperature in the lo ...
Do manganese nodules grow or dissolve after burial
... manganese nodules at the sediment-water interface. Possible mechanisms to maintain nodules at the sediment-water interface could be the influence of ocean bottom currents and the reworking of sediment by benthic organisms (Glasby, 1977; Glasby et al., 1982). Alternatively, due to the small density d ...
... manganese nodules at the sediment-water interface. Possible mechanisms to maintain nodules at the sediment-water interface could be the influence of ocean bottom currents and the reworking of sediment by benthic organisms (Glasby, 1977; Glasby et al., 1982). Alternatively, due to the small density d ...
Historical records of coastal eutrophication
... Tyson and Pearson, 1991) but significant numbers of publications only began to appear in the 1990s and have increased substantially since 2000. They have tended to concentrate in certain areas, notably the Louisiana continental shelf, Chesapeake Bay, Norwegian fjords and the Baltic Sea (Fig. 1). A v ...
... Tyson and Pearson, 1991) but significant numbers of publications only began to appear in the 1990s and have increased substantially since 2000. They have tended to concentrate in certain areas, notably the Louisiana continental shelf, Chesapeake Bay, Norwegian fjords and the Baltic Sea (Fig. 1). A v ...
UHP metamorphism in garnet peridotite, Cuaba unit, Rio San Juan
... Four attributes suggest low-P/T (UHT) conditions: (1) Sequence of mineral assemblages, (2) nature of associated rocks, (3) Cr-in-clinopyroxene, Mg2Si2O6-in-clinopyroxene thermobarometry (>1.8 Gpa, >900 ˚C), and (4) tectonic setting. However, the thermobarometry is questionable because of low Cr in c ...
... Four attributes suggest low-P/T (UHT) conditions: (1) Sequence of mineral assemblages, (2) nature of associated rocks, (3) Cr-in-clinopyroxene, Mg2Si2O6-in-clinopyroxene thermobarometry (>1.8 Gpa, >900 ˚C), and (4) tectonic setting. However, the thermobarometry is questionable because of low Cr in c ...
Behaviour of high field strength elements in subduction zones
... on the HFSE mobility at different conditions in the subarc mantle. Hf – Nd isotope and systematic Zr/Hf and Lu/Hf covariations illustrate that Zr – Hf and Lu are immobile in fluid-dominated regimes. Hf – Nd isotope compositions furthermore indicate the presence of ‘‘Indian’’ type depleted mantle ben ...
... on the HFSE mobility at different conditions in the subarc mantle. Hf – Nd isotope and systematic Zr/Hf and Lu/Hf covariations illustrate that Zr – Hf and Lu are immobile in fluid-dominated regimes. Hf – Nd isotope compositions furthermore indicate the presence of ‘‘Indian’’ type depleted mantle ben ...
Earth`s heterogeneous mantle: A product of convection
... fundamental questions. The large amount of available isotope data in oceanic basalts shows that, statistically, only two principal compositional vectors capture the essential features of the data. Care must be taken, however, when estimating the isotopic composition of mantle from basalt samples. Th ...
... fundamental questions. The large amount of available isotope data in oceanic basalts shows that, statistically, only two principal compositional vectors capture the essential features of the data. Care must be taken, however, when estimating the isotopic composition of mantle from basalt samples. Th ...
The Mg isotopic composition of Cenozoic seawater – evidence for a
... −1.34 ± 0.06h and −2.59 ± 0.12h (2σsd ; n = 46). Both measured values are indistinguishable from published values (δ 25 Mg = −1.33 ± 0.07h; δ 26 Mg = −2.58 ± 0.14h; Galy et al., 2003). A total of six samples (two carbonates and four pore fluids), measured on both the GV Isoprobe P and the Thermo Nept ...
... −1.34 ± 0.06h and −2.59 ± 0.12h (2σsd ; n = 46). Both measured values are indistinguishable from published values (δ 25 Mg = −1.33 ± 0.07h; δ 26 Mg = −2.58 ± 0.14h; Galy et al., 2003). A total of six samples (two carbonates and four pore fluids), measured on both the GV Isoprobe P and the Thermo Nept ...
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.