Chapter 21: Metamorphism
... • Mild deformation, no igneous intrusions discovered • Fine-grained, high-temperature phases, glassy ash: very susceptible to metamorphic alteration • Metamorphic effects attributed to increased temperature and pressure due to burial • Diagenesis grades into the formation of zeolites, prehnite, ...
... • Mild deformation, no igneous intrusions discovered • Fine-grained, high-temperature phases, glassy ash: very susceptible to metamorphic alteration • Metamorphic effects attributed to increased temperature and pressure due to burial • Diagenesis grades into the formation of zeolites, prehnite, ...
as a PDF - Dipartimento di Scienze della Terra
... subduction hinges relative to the mantle. However, the velocity of the subduction hinges cannot be measured precisely, as shown in Doglioni et al. (2007), Fig. 8. The motion of the subduction hinge is for example computed assuming that it equals the amount of backarc spreading (e.g., Heuret and Lall ...
... subduction hinges relative to the mantle. However, the velocity of the subduction hinges cannot be measured precisely, as shown in Doglioni et al. (2007), Fig. 8. The motion of the subduction hinge is for example computed assuming that it equals the amount of backarc spreading (e.g., Heuret and Lall ...
Near-Ultrahigh Pressure Processing of Continental Crust: Miocene
... Only xenoliths erupted from ultrahigh-pressure settings can provide this important information, but such rocks are exceptionally rare. We report here on the petrology, physical properties, and geochronology of a Miocene xenolith suite from the Pamir that has captured nearultrahigh pressure metamorph ...
... Only xenoliths erupted from ultrahigh-pressure settings can provide this important information, but such rocks are exceptionally rare. We report here on the petrology, physical properties, and geochronology of a Miocene xenolith suite from the Pamir that has captured nearultrahigh pressure metamorph ...
High-Mg# andesitic lavas of the Shisheisky Complex, Northern
... produced by melting of eclogite or pyroxenite (van Keken et al. 2002; Kelemen et al. 2003b; Conder 2005). Despite the basic differences between the two models for high-Mg# andesite genesis described earlier, both interpretations imply that high-Mg# andesites are a primary arc magma type that is gene ...
... produced by melting of eclogite or pyroxenite (van Keken et al. 2002; Kelemen et al. 2003b; Conder 2005). Despite the basic differences between the two models for high-Mg# andesite genesis described earlier, both interpretations imply that high-Mg# andesites are a primary arc magma type that is gene ...
MAJOR-ELEMENT CHEMISTRY OF PLUTONIC ROCK SUITES
... and normative plagioclase are preferred because the differences between the two types of suites are more clearly shown. The calc/alkali index is a useful classification of compressional and extensional suites. The calc/alkali indexes were estimated from curves prepared b y two methods. Smooth, hand- ...
... and normative plagioclase are preferred because the differences between the two types of suites are more clearly shown. The calc/alkali index is a useful classification of compressional and extensional suites. The calc/alkali indexes were estimated from curves prepared b y two methods. Smooth, hand- ...
u series disequilibria: insights into mantle melting and
... and melt-matrix interaction); (2) the elapse of time since the fractionation event during which radioactive decay will occur (e.g., melt transport time from mantle source regions to the crust, residence time in crustal magma reservoirs, and time since lava eruption); and (3) surface weathering or hy ...
... and melt-matrix interaction); (2) the elapse of time since the fractionation event during which radioactive decay will occur (e.g., melt transport time from mantle source regions to the crust, residence time in crustal magma reservoirs, and time since lava eruption); and (3) surface weathering or hy ...
PDF
... RECEIVED JUNE 30, 2001; REVISED TYPESCRIPT ACCEPTED APRIL 11, 2002 The Ueno Basalts of central Japan comprise a monogenetic volcanic cone complex that was active between 2·76 and 1·34 Ma. Basalts were erupted at more than 14 centers scattered over a region 40 km in diameter. Alkali basalt was erupte ...
... RECEIVED JUNE 30, 2001; REVISED TYPESCRIPT ACCEPTED APRIL 11, 2002 The Ueno Basalts of central Japan comprise a monogenetic volcanic cone complex that was active between 2·76 and 1·34 Ma. Basalts were erupted at more than 14 centers scattered over a region 40 km in diameter. Alkali basalt was erupte ...
Earth`s first two billion years—The era of internally
... The magmatic and tectonic processes of the pre–2.5 Ga hot, young Earth differed profoundly from those of the modern planet. The ancient rocks differ strikingly in individual and collective composition, occurrence, association, and structure from modern rocks. Widespread forcing of Archean geology in ...
... The magmatic and tectonic processes of the pre–2.5 Ga hot, young Earth differed profoundly from those of the modern planet. The ancient rocks differ strikingly in individual and collective composition, occurrence, association, and structure from modern rocks. Widespread forcing of Archean geology in ...
Geological Society of America Bulletin
... belts. Magmatism during each of these phases produces spatially and temporally associated, mafic-ultramafic to highly evolved rock assemblages. These rock units, which have varying internal structures, geochemical affinities, and age ranges, and originally formed in different geodynamic settings, co ...
... belts. Magmatism during each of these phases produces spatially and temporally associated, mafic-ultramafic to highly evolved rock assemblages. These rock units, which have varying internal structures, geochemical affinities, and age ranges, and originally formed in different geodynamic settings, co ...
Geodynpub_files/Boutelier, Chemenda, 2011
... are employed to model these layers. Finally, since we are interested in the large deformation of the lithosphere we must also consider the material strain softening behavior, required in order to produce and maintain lithospheric-scale shear zones. In the brittle layers of the lithosphere the locali ...
... are employed to model these layers. Finally, since we are interested in the large deformation of the lithosphere we must also consider the material strain softening behavior, required in order to produce and maintain lithospheric-scale shear zones. In the brittle layers of the lithosphere the locali ...
Paper 3.2 Mb pdf - Miles F Osmaston
... for epeirogeny) to the plate tectonics armory, we will then derive an interpretation of Alpine history, concluding with brief comparative remarks on other HP-UHP belts. To complement the understanding of our proposed mechanism for differential thermal epeirogenic action in the context of block-and-b ...
... for epeirogeny) to the plate tectonics armory, we will then derive an interpretation of Alpine history, concluding with brief comparative remarks on other HP-UHP belts. To complement the understanding of our proposed mechanism for differential thermal epeirogenic action in the context of block-and-b ...
STRIKE-SLIP AND OBLIQUE
... R Riedel shears are normally the first subsidiary fractures to occur and generally build the most prominent set. They develop at an acute angle, typically 10-20° clockwise to a dextral main fault, anticlockwise to a sinistral strike-slip fault. They often form an en échelon and overstepping array sy ...
... R Riedel shears are normally the first subsidiary fractures to occur and generally build the most prominent set. They develop at an acute angle, typically 10-20° clockwise to a dextral main fault, anticlockwise to a sinistral strike-slip fault. They often form an en échelon and overstepping array sy ...
science china - Woods Hole Oceanographic Institution
... from 80 Ma. Since 80 Ma, the ridge axis had migrated about 2500 km from DII to the Rodriguez Triple Junction (RTJ, 70°E) and sequentially formed GA, AII and MEL FZs (Fracture Zones) and so on [19]. Currently, the AB transform fault, with a length of about 1000 km, separates the SWIR into eastern and ...
... from 80 Ma. Since 80 Ma, the ridge axis had migrated about 2500 km from DII to the Rodriguez Triple Junction (RTJ, 70°E) and sequentially formed GA, AII and MEL FZs (Fracture Zones) and so on [19]. Currently, the AB transform fault, with a length of about 1000 km, separates the SWIR into eastern and ...
Seismic velocity structure of the rifted margin of the eastern Grand
... (NGFZ) and Charlie-Gibbs (CGFZ) fracture zones. The Mid-Atlantic Ridge, Flemish Cap, and Galicia Bank are marked with the 2000 m bathymetry contour. Gray shaded ages of the seafloor [Müller et al., 1997] are Jurassic (Ju), Berriasian to Barremian (together comprising the Neocomian, Be-Ba), Aptian a ...
... (NGFZ) and Charlie-Gibbs (CGFZ) fracture zones. The Mid-Atlantic Ridge, Flemish Cap, and Galicia Bank are marked with the 2000 m bathymetry contour. Gray shaded ages of the seafloor [Müller et al., 1997] are Jurassic (Ju), Berriasian to Barremian (together comprising the Neocomian, Be-Ba), Aptian a ...
SCIENCE CHINA Magmatism during continental collision
... the India plate is still moving northward at a speed of 3–4 cm yr−1. Therefore, for the Himalaya Orogen, the orogeny might have lasted for 65–70 Myr, but it remains further clarification whether the Himalaya Orogen is still the continuation of continental collision or in the post-collision process. ...
... the India plate is still moving northward at a speed of 3–4 cm yr−1. Therefore, for the Himalaya Orogen, the orogeny might have lasted for 65–70 Myr, but it remains further clarification whether the Himalaya Orogen is still the continuation of continental collision or in the post-collision process. ...
ž / Evidence from mantle xenoliths for relatively thin -100
... Garnet peridotite xenoliths in the Quaternary Pali-Aike alkali olivine basalts of southernmost South America are samples of the deeper portion of continental lithosphere formed by accretion along the western margin of Gondwanaland during the Phanerozoic. Core compositions of minerals in garnet perid ...
... Garnet peridotite xenoliths in the Quaternary Pali-Aike alkali olivine basalts of southernmost South America are samples of the deeper portion of continental lithosphere formed by accretion along the western margin of Gondwanaland during the Phanerozoic. Core compositions of minerals in garnet perid ...
univERsity oF copEnhAGEn
... zones, play major roles in the shaping of the continental crust by tectonic and magmatic processes. These processes and their importance for forming the continental lithosphere have been widely discussed with focus on the various tectonic regimes. Additionally, the interaction of mantle upwelling (p ...
... zones, play major roles in the shaping of the continental crust by tectonic and magmatic processes. These processes and their importance for forming the continental lithosphere have been widely discussed with focus on the various tectonic regimes. Additionally, the interaction of mantle upwelling (p ...
Moho and magmatic underplating
... zones, play major roles in the shaping of the continental crust by tectonic and magmatic processes. These processes and their importance for forming the continental lithosphere have been widely discussed with focus on the various tectonic regimes. Additionally, the interaction of mantle upwelling (p ...
... zones, play major roles in the shaping of the continental crust by tectonic and magmatic processes. These processes and their importance for forming the continental lithosphere have been widely discussed with focus on the various tectonic regimes. Additionally, the interaction of mantle upwelling (p ...
Geophysical and Petrological Constraints on Ocean Plate Dynamics
... “While the thought of a highly mobile sea floor may seem alarming at first, it does little violence to geological history.” Robert S. Dietz [1961] The concept of seafloor spreading [Hess, 1960] led to the modern understanding of plate tectonics where discrete rigid lithospheric plates move with resp ...
... “While the thought of a highly mobile sea floor may seem alarming at first, it does little violence to geological history.” Robert S. Dietz [1961] The concept of seafloor spreading [Hess, 1960] led to the modern understanding of plate tectonics where discrete rigid lithospheric plates move with resp ...
The Central Asia collision zone: numerical present-day kinematics
... transects. In the northern profile (northern Zagros), the LAB rises sharply below the Sanandaj Sirjan Zone in a narrow region of ~90 km, whereas in the southern profile (central Zagros), rising occurs in wider region, from the Zagros Fold-and-Thrust Belt to the Sanandaj Sirjan Zone. The best fit of ...
... transects. In the northern profile (northern Zagros), the LAB rises sharply below the Sanandaj Sirjan Zone in a narrow region of ~90 km, whereas in the southern profile (central Zagros), rising occurs in wider region, from the Zagros Fold-and-Thrust Belt to the Sanandaj Sirjan Zone. The best fit of ...
Toward the reconciliation of seismological and petrological
... Models for the evolution of the oceanic lithosphere are based on the cooling of homogeneous material, even when sophisticated representations of material properties are used [e.g., Grose and Afonso, 2013]. Any fine-scale heterogeneity will simply be absorbed into a mixed assemblage, whose overall pro ...
... Models for the evolution of the oceanic lithosphere are based on the cooling of homogeneous material, even when sophisticated representations of material properties are used [e.g., Grose and Afonso, 2013]. Any fine-scale heterogeneity will simply be absorbed into a mixed assemblage, whose overall pro ...
Downdip landward limit of Cascadia great earthquake rupture
... interseismic plate convergence slip deficit based on the magnitude of coseismic coastal subsidence [Leonard et al., 2004; 2010]. The one area of uncertainty is off central Oregon where the inferred locked/rupture zone is well offshore such that the expected and observed interseismic uplift rate and c ...
... interseismic plate convergence slip deficit based on the magnitude of coseismic coastal subsidence [Leonard et al., 2004; 2010]. The one area of uncertainty is off central Oregon where the inferred locked/rupture zone is well offshore such that the expected and observed interseismic uplift rate and c ...
short and long-term folding and faulting of the lithosphere under
... As we want to study how the lithosphere responds when subjected to a force, in our case a compression, it is important to introduce two important concepts on the field of geodynamics: stress and strain. Stress can be defined as the internal distribution and intensity of a force acting at any point w ...
... As we want to study how the lithosphere responds when subjected to a force, in our case a compression, it is important to introduce two important concepts on the field of geodynamics: stress and strain. Stress can be defined as the internal distribution and intensity of a force acting at any point w ...
PDF
... [1] We present major, trace element, and Pb‐Sr‐Nd‐Hf isotope data for Quaternary basalt and basaltic andesite lavas from cross‐chain volcanoes in the northern Izu (N‐Izu) arc. Lavas from Izu‐Oshima, Toshima, Udonejima, and Niijima islands show consistent chemical changes with depth to the Wadati‐Ben ...
... [1] We present major, trace element, and Pb‐Sr‐Nd‐Hf isotope data for Quaternary basalt and basaltic andesite lavas from cross‐chain volcanoes in the northern Izu (N‐Izu) arc. Lavas from Izu‐Oshima, Toshima, Udonejima, and Niijima islands show consistent chemical changes with depth to the Wadati‐Ben ...
Post-glacial rebound
Post-glacial rebound (sometimes called continental rebound) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Post-glacial rebound and isostatic depression are different parts of a process known as either glacial isostasy, glacial isostatic adjustment, or glacioisostasy. Glacioisostasy is the solid Earth deformation associated with changes in ice mass distribution. The most obvious and direct affects of post-glacial rebound are readily apparent in northern Europe (especially Scotland, Estonia, Latvia, Fennoscandia, and northern Denmark), Siberia, Canada, the Great Lakes of Canada and the United States, the coastal region of the US state of Maine, parts of Patagonia, and Antarctica. However, through processes known as ocean siphoning and continental levering, the effects of post-glacial rebound on sea-level are felt globally far from the locations of current and former ice sheets.