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... increasing silica content is associated with stronger EMII (Enriched Mantle II) isotope affinities and fluid mobile element abundances. A progressive AFC (assimilation–fractional crystallization) model assuming assimilation of a low-K silicic melt reproduces the chemical variations observed in the sub ...
... increasing silica content is associated with stronger EMII (Enriched Mantle II) isotope affinities and fluid mobile element abundances. A progressive AFC (assimilation–fractional crystallization) model assuming assimilation of a low-K silicic melt reproduces the chemical variations observed in the sub ...
On subducting slab entrainment of buoyant asthenosphere
... flow (Fig. 1a). If, however, the asthenosphere layer – presumed to underlie at least much of the oceanic lithosphere – is itself less dense and viscous than the underlying mantle, then the resulting asthenosphere circulation can be strongly altered in ways that may have significant geological conseque ...
... flow (Fig. 1a). If, however, the asthenosphere layer – presumed to underlie at least much of the oceanic lithosphere – is itself less dense and viscous than the underlying mantle, then the resulting asthenosphere circulation can be strongly altered in ways that may have significant geological conseque ...
imp prefaz.qxp - Istituto Nazionale di Oceanografia e di Geofisica
... some specific regions, where the recording was done by local and transitory seismological networks or where the seismic monitoring has been established only in recent years. Looking at the three maps a general trend of deepening of the earthquakes can be remarked when moving from north to south; mor ...
... some specific regions, where the recording was done by local and transitory seismological networks or where the seismic monitoring has been established only in recent years. Looking at the three maps a general trend of deepening of the earthquakes can be remarked when moving from north to south; mor ...
doc Exam notes
... - From H-R Diagram, we can know how intrinsicly bright a star is. - By comparing the apparent and absolute magnitudes, we can determine the distance to the star. 3.1.8 A Distance Scale Based on the Intrinsic Brightness of Galaxies - For the closest galaxies, we can determine their size if we know th ...
... - From H-R Diagram, we can know how intrinsicly bright a star is. - By comparing the apparent and absolute magnitudes, we can determine the distance to the star. 3.1.8 A Distance Scale Based on the Intrinsic Brightness of Galaxies - For the closest galaxies, we can determine their size if we know th ...
Physically Based Terrain Generation
... planets to evolve into their current shape are described by plate tectonics. The theory of plate tectonics states that Earth's surface is divided into relatively few rigid areas called plates that move depending on and affecting the movement of all other plates [9, p. 103]. Erosion is a process that ...
... planets to evolve into their current shape are described by plate tectonics. The theory of plate tectonics states that Earth's surface is divided into relatively few rigid areas called plates that move depending on and affecting the movement of all other plates [9, p. 103]. Erosion is a process that ...
Uplift at lithospheric swellsI: seismic and gravity
... that hotspots may be intermittently active for >100 Ma, often with more than 5 Ma between major eruptive phases, and some can be traced back to large igneous provinces using the age-progression of island chains and records of palaeoplate motions (Duncan & ...
... that hotspots may be intermittently active for >100 Ma, often with more than 5 Ma between major eruptive phases, and some can be traced back to large igneous provinces using the age-progression of island chains and records of palaeoplate motions (Duncan & ...
Limits on lateral density and velocity variations in the Earth`s outer core
... The viscosity of the core is not well known precisely because (unlike the mantle) it is dynamically unimportant. At the top of the core, nutation studies limit the kinematic viscosity v.;; 10 5 cm 2 s- 1 (Toomre 1974; see also Rochester 1976). Although seismic constraints are more global, yet weaker ...
... The viscosity of the core is not well known precisely because (unlike the mantle) it is dynamically unimportant. At the top of the core, nutation studies limit the kinematic viscosity v.;; 10 5 cm 2 s- 1 (Toomre 1974; see also Rochester 1976). Although seismic constraints are more global, yet weaker ...
Multiple sulfur isotope composition of oxidized Samoan melts and
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
Lithosphere, Earth`s Interior and Paleo-Environment
... Indian subcontinent has been unique and perhaps the most mobile (20 cm/yr between 90 and 53 Ma) , with active history of rifting, multiple plume interactions and continental breakups. It contains several Archean-Proterozoic cratons, separated by rift valleys, sutures and mega-lineaments, which have ...
... Indian subcontinent has been unique and perhaps the most mobile (20 cm/yr between 90 and 53 Ma) , with active history of rifting, multiple plume interactions and continental breakups. It contains several Archean-Proterozoic cratons, separated by rift valleys, sutures and mega-lineaments, which have ...
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... western Pacific have a generally Indian character, whereas the basins in the south (Havre Trough and Valu Fa Ridge) have a Pacific character. This difference is mirrored in the compositions of the adjacent arcs: the Kermadec arc trenchward of the Havre Trough, and the Tofua arc volcano Ata trenchwar ...
... western Pacific have a generally Indian character, whereas the basins in the south (Havre Trough and Valu Fa Ridge) have a Pacific character. This difference is mirrored in the compositions of the adjacent arcs: the Kermadec arc trenchward of the Havre Trough, and the Tofua arc volcano Ata trenchwar ...
Abyssal peridotites, very slow spreading ridges and
... SUMMARY: The SW Indian and American-Antarctic Ridges are two of the world's slowest spreading ocean ridges (less than 1 cm a-l), making them the low end-members for rate of ocean ridge magma supply. Two-thirds of the rocks dredged at the numerous large offset transforms along the ridges are residual ...
... SUMMARY: The SW Indian and American-Antarctic Ridges are two of the world's slowest spreading ocean ridges (less than 1 cm a-l), making them the low end-members for rate of ocean ridge magma supply. Two-thirds of the rocks dredged at the numerous large offset transforms along the ridges are residual ...
Scandium Iain M. Samson Department of Earth and Environmental
... with average values of 31, 19, and 14 ppm for the lower, middle, and upper crust, respectively, and an average continental crust value of 22 ppm (Rudnick and Gao 2003). It occurs in higher concentrations in oceanic crust as reflected in values in MORB of between 34 and 48 ppm (Klein 2003). Thus, as ...
... with average values of 31, 19, and 14 ppm for the lower, middle, and upper crust, respectively, and an average continental crust value of 22 ppm (Rudnick and Gao 2003). It occurs in higher concentrations in oceanic crust as reflected in values in MORB of between 34 and 48 ppm (Klein 2003). Thus, as ...
File - Ms. Fergus Science
... earthquakes. For example, the English playwright Shakespeare wrote, “The earth did shake when I was born” (Henry IV, Part I). The Greek philosopher Aristotle gave a natural explanation for earthquakes. He thought that atmospheric winds were drawn into the earth’s interior. These winds caused fires t ...
... earthquakes. For example, the English playwright Shakespeare wrote, “The earth did shake when I was born” (Henry IV, Part I). The Greek philosopher Aristotle gave a natural explanation for earthquakes. He thought that atmospheric winds were drawn into the earth’s interior. These winds caused fires t ...
volcanism and intrusions of the deccan traps, india: geochemistry
... Igatpuri, Neral, Thakurvadi, Bhimashankar and Khandala) on the basis of their chemical and isotopic compositions. Among the upper formations, the Ambenali fm. presents the highest εNd i=66Ma (+4 to +7) and the lowest 87Sr/86Sri (0.7038 to 0.7044), suggesting that it is the least contaminated formati ...
... Igatpuri, Neral, Thakurvadi, Bhimashankar and Khandala) on the basis of their chemical and isotopic compositions. Among the upper formations, the Ambenali fm. presents the highest εNd i=66Ma (+4 to +7) and the lowest 87Sr/86Sri (0.7038 to 0.7044), suggesting that it is the least contaminated formati ...
Structure of the crust and uppermost mantle of Iceland from
... pro¢le cannot be calculated directly from the seismic model, since no data are available for subMoho P wave velocities. Instead, a mantle density of 3260 kg m33 is used in the modelling. This value is derived from the estimated average mantle (harzburgite) composition below Iceland at 40 km depth an ...
... pro¢le cannot be calculated directly from the seismic model, since no data are available for subMoho P wave velocities. Instead, a mantle density of 3260 kg m33 is used in the modelling. This value is derived from the estimated average mantle (harzburgite) composition below Iceland at 40 km depth an ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.