PDF (Chapter 3. The Crust and Upper Mantle)
... of the crust is based solely on seismological data. The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types-continental, transitional and oceanic. Oceanic crust generally ranges from 5 to 15 km in thickness and comprises 60 percent ...
... of the crust is based solely on seismological data. The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types-continental, transitional and oceanic. Oceanic crust generally ranges from 5 to 15 km in thickness and comprises 60 percent ...
Lecture 18
... be the case, the idea has been accepted as a sort of working hypothesis by mantle geochemists (although it is unclear exactly how many classes there are, some prefer 4 or 6). The next question to ask is what processes have lead to the distinct identities of these reservoirs. For the MORB reservoir, ...
... be the case, the idea has been accepted as a sort of working hypothesis by mantle geochemists (although it is unclear exactly how many classes there are, some prefer 4 or 6). The next question to ask is what processes have lead to the distinct identities of these reservoirs. For the MORB reservoir, ...
The Caribbean Ocean Plateau – an overview
... refraction profiles recording the mantle were converted to densities and the total mass/sq cm was summed to a depth of 32 km. The values were low (light) compared with standard ocean section and possibly reflected low-density mantle. Edgar & Saunders et al. (1973) stated that crustal layers of the C ...
... refraction profiles recording the mantle were converted to densities and the total mass/sq cm was summed to a depth of 32 km. The values were low (light) compared with standard ocean section and possibly reflected low-density mantle. Edgar & Saunders et al. (1973) stated that crustal layers of the C ...
A Geochemical Study of Crustal Plutonic Rocks from the Southern
... The locations of the dredges are significant as the area contains volcanic rocks (forearc basalts and boninites) that have been pivotal in explaining processes that occur when one lithospheric plate initially begins to subduct beneath another. The plutonic rocks have been classified based on petrolo ...
... The locations of the dredges are significant as the area contains volcanic rocks (forearc basalts and boninites) that have been pivotal in explaining processes that occur when one lithospheric plate initially begins to subduct beneath another. The plutonic rocks have been classified based on petrolo ...
Mantle Meltıng Beneath Mıd-Ocean rıdges
... Melting is a primary means by which the earth cools: seafloor spreading brings hot mantle from depth to the colder surface. Because we normally think that melting occurs through heating (e.g., putting a slab of butter in a frying pan), it may seem paradoxical to say the earth melts while cooling dow ...
... Melting is a primary means by which the earth cools: seafloor spreading brings hot mantle from depth to the colder surface. Because we normally think that melting occurs through heating (e.g., putting a slab of butter in a frying pan), it may seem paradoxical to say the earth melts while cooling dow ...
Origin of ocean island basalts: A new perspective from petrology
... isotopic compositions (rectangles on the left vertical axes) of these ancient ocean crusts are quite depleted after 2.0 Ga and 1.0 Ga evolution with eSr < 24, eNd > 8.4, and eHf > 19. They are, on average, much more depleted than most of the present-day OIB [Albarède, 1995; Salters and White, 1998 ...
... isotopic compositions (rectangles on the left vertical axes) of these ancient ocean crusts are quite depleted after 2.0 Ga and 1.0 Ga evolution with eSr < 24, eNd > 8.4, and eHf > 19. They are, on average, much more depleted than most of the present-day OIB [Albarède, 1995; Salters and White, 1998 ...
Mantle Melting Beneath Mid-Ocean Ridges The Harvard community
... Melting is a primary means by which the earth cools: seafloor spreading brings hot mantle from depth to the colder surface. Because we normally think that melting occurs through heating (e.g., putting a slab of butter in a frying pan), it may seem paradoxical to say the earth melts while cooling dow ...
... Melting is a primary means by which the earth cools: seafloor spreading brings hot mantle from depth to the colder surface. Because we normally think that melting occurs through heating (e.g., putting a slab of butter in a frying pan), it may seem paradoxical to say the earth melts while cooling dow ...
Human Health and Vulnerability in the Nyiragongo Volcano Crisis
... people’s lives. Often concealed by cloud, Nyiragongo has been reluctant to yield its secrets. The earliest European explorers were drawn to the red glow of its crater against the night sky, and an expedition eventually forged a way through almost impenetrable vegetation to reach the summit in 1894. ...
... people’s lives. Often concealed by cloud, Nyiragongo has been reluctant to yield its secrets. The earliest European explorers were drawn to the red glow of its crater against the night sky, and an expedition eventually forged a way through almost impenetrable vegetation to reach the summit in 1894. ...
Open-system Behavior during Pluton^Wall
... wall-rock assimilation. In element^element mixing diagrams, reactive wall-rock assimilation will result in nonlinear mixing arrays, unlike direct wall-rock assimilation, which is linear. Of course, any magmatic recharge, fractional crystallization, diffusive decoupling or selective assimilation of w ...
... wall-rock assimilation. In element^element mixing diagrams, reactive wall-rock assimilation will result in nonlinear mixing arrays, unlike direct wall-rock assimilation, which is linear. Of course, any magmatic recharge, fractional crystallization, diffusive decoupling or selective assimilation of w ...
Flow and melting of a heterogeneous mantle
... Understanding the partial melting process is key to our ability to relate geochemical characteristics of hotspot and midocean ridge lavas to the dynamics and chemical structure of the mantle. We present a method of computing the trace-element and isotopic compositions of magmas generated by melting ...
... Understanding the partial melting process is key to our ability to relate geochemical characteristics of hotspot and midocean ridge lavas to the dynamics and chemical structure of the mantle. We present a method of computing the trace-element and isotopic compositions of magmas generated by melting ...
View/Open - Earth
... place today in the northern Thetis and southern Nereus tips. Basaltic glasses major and trace element composition suggests a rift-to-drift transition marked by magmatic activity with typical MORB signature, with no contamination by continental lithosphere, but with slight differences in mantle sourc ...
... place today in the northern Thetis and southern Nereus tips. Basaltic glasses major and trace element composition suggests a rift-to-drift transition marked by magmatic activity with typical MORB signature, with no contamination by continental lithosphere, but with slight differences in mantle sourc ...
Three distinct types of hotspots in the Earth`s mantle
... There are on the order of 40 remaining, nonprimary hotspots. These do not have enough indications of a deep, lower mantle origin in our view. We will see below that they can themselves be subdivided into two groups, one of which may have a transition zone origin whereas the other would be much more ...
... There are on the order of 40 remaining, nonprimary hotspots. These do not have enough indications of a deep, lower mantle origin in our view. We will see below that they can themselves be subdivided into two groups, one of which may have a transition zone origin whereas the other would be much more ...
volcano - cloudfront.net
... It is relatively poor in silica. • Because of its composition, lava from mantle rock cools to form dark-colored rock. • The term mafic describes magma, lava, and rocks that are rich in iron and magnesium. ...
... It is relatively poor in silica. • Because of its composition, lava from mantle rock cools to form dark-colored rock. • The term mafic describes magma, lava, and rocks that are rich in iron and magnesium. ...
Adakitic Dacites Formed by Intracrustal Crystal Fractionation of
... (3628S, Chile) are the only reported occurrence of adakitic volcanic rocks in the Quaternary Andean Southern Volcanic Zone (33^468S). Dacites of this volcano are chemically distinct from other evolved magmas of the region in that they have high La/Yb (15^20) and Sr/Y (60^90) ratios and systematical ...
... (3628S, Chile) are the only reported occurrence of adakitic volcanic rocks in the Quaternary Andean Southern Volcanic Zone (33^468S). Dacites of this volcano are chemically distinct from other evolved magmas of the region in that they have high La/Yb (15^20) and Sr/Y (60^90) ratios and systematical ...
Spreading Continents Kick-Started Plate Tectonics Plate tectonics
... (Extended Data Fig. 3b), ii/ the slab detaches then the lid stabilizes (Figs. 1a3-4 and Extended Data Fig. ...
... (Extended Data Fig. 3b), ii/ the slab detaches then the lid stabilizes (Figs. 1a3-4 and Extended Data Fig. ...
No Slide Title
... It is relatively poor in silica. • Because of its composition, lava from mantle rock cools to form dark-colored rock. • The term mafic describes magma, lava, and rocks that are rich in iron and magnesium. ...
... It is relatively poor in silica. • Because of its composition, lava from mantle rock cools to form dark-colored rock. • The term mafic describes magma, lava, and rocks that are rich in iron and magnesium. ...
2. Disaster setting - World Health Organization
... people’s lives. Often concealed by cloud, Nyiragongo has been reluctant to yield its secrets. The earliest European explorers were drawn to the red glow of its crater against the night sky, and an expedition eventually forged a way through almost impenetrable vegetation to reach the summit in 1894. ...
... people’s lives. Often concealed by cloud, Nyiragongo has been reluctant to yield its secrets. The earliest European explorers were drawn to the red glow of its crater against the night sky, and an expedition eventually forged a way through almost impenetrable vegetation to reach the summit in 1894. ...
Ophiolites: Figments of Oceanic Lithosphere? Geological Society
... basic magma in relatively narrow zones, and such conditions might be found in a variety of tectonic settings. However, geochemical evidence, in particular arguments based on 'immobile' elements, have been proposed to resolve the problem of tectonic setting. Clearly, if geochemical methods are to be ...
... basic magma in relatively narrow zones, and such conditions might be found in a variety of tectonic settings. However, geochemical evidence, in particular arguments based on 'immobile' elements, have been proposed to resolve the problem of tectonic setting. Clearly, if geochemical methods are to be ...
Intracratonic asthenosphere upwelling and lithosphere rejuvenation
... anhydrous spinel lherzolites. Major and trace element analyses on bulk rocks and constituent mineral phases show that the primary compositions are widely overprinted by metasomatic processes. Trace element modelling of the metasomatised clinopyroxenes allows the inference that the metasomatic agents ...
... anhydrous spinel lherzolites. Major and trace element analyses on bulk rocks and constituent mineral phases show that the primary compositions are widely overprinted by metasomatic processes. Trace element modelling of the metasomatised clinopyroxenes allows the inference that the metasomatic agents ...
"postorogenie" magmatism
... these "postorogenie" magmatic suites, the critical geodynamic problems related to their genesis remain unanswered. However, the geodynamic and compositional data allow some inferences regarding their origin. First, the broad distribution of "postorogenie" magmatic suites through space and time sugge ...
... these "postorogenie" magmatic suites, the critical geodynamic problems related to their genesis remain unanswered. However, the geodynamic and compositional data allow some inferences regarding their origin. First, the broad distribution of "postorogenie" magmatic suites through space and time sugge ...
Niu, Y., Generation and evolution of basaltic magmas
... more refractory component of the source rock. The bulk composition of the resultant melt can only be more felsic (i.e., higher SiO2) or less mafic (i.e., lower FeO and MgO, and lower MgO/FeO ratio) than the source rock. In other words, basaltic melts result from partial melting of mantle peridotites ...
... more refractory component of the source rock. The bulk composition of the resultant melt can only be more felsic (i.e., higher SiO2) or less mafic (i.e., lower FeO and MgO, and lower MgO/FeO ratio) than the source rock. In other words, basaltic melts result from partial melting of mantle peridotites ...
Mantle plumes persevere
... Ocean. In these cases, the mantle-plume origin perseveres. These hotspots show the telltale signs of a deep mantle source, possibly near the core–mantle boundary, that has been active for a long time. However, the southward movement of the Hawaiian plume tells us that we need to entertain more sophi ...
... Ocean. In these cases, the mantle-plume origin perseveres. These hotspots show the telltale signs of a deep mantle source, possibly near the core–mantle boundary, that has been active for a long time. However, the southward movement of the Hawaiian plume tells us that we need to entertain more sophi ...
Basalt
Basalt (pronounced /bəˈsɔːlt/, /ˈbæsɒlt/, /ˈbæsɔːlt/, or /ˈbeɪsɔːlt/)is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of lava basalt flows.