ON THE SCALE OF MANTLE CONVECTION The relative motion of
... motions. The scale of any such convection is at present unknown, but it should correspond to the size of the plates. Since these vary in scale from very large plates, such as the Pacific plate (-6000 km), to smaller plates, such as the Caribbean (- 1000 km), we might expect a corresponding variation ...
... motions. The scale of any such convection is at present unknown, but it should correspond to the size of the plates. Since these vary in scale from very large plates, such as the Pacific plate (-6000 km), to smaller plates, such as the Caribbean (- 1000 km), we might expect a corresponding variation ...
Slide 1 - Global Heat Flow Database
... The transect across the Cascades between latitudes 45 N to 49 N shows a narrow band of high HFD over the volcanic arc followed by a gradual increase in HFD from 60 mW m-2 to 80 mW m-2 over a distance of about 800 km. In the region of the Idaho Batholith, between 800 km and 1150 km, HFD is about 80 ...
... The transect across the Cascades between latitudes 45 N to 49 N shows a narrow band of high HFD over the volcanic arc followed by a gradual increase in HFD from 60 mW m-2 to 80 mW m-2 over a distance of about 800 km. In the region of the Idaho Batholith, between 800 km and 1150 km, HFD is about 80 ...
Global Tectonics - dynamicearth.de
... named after the Komati Formation in the Barberton Greenstone belt of the Kaapvaal craton, South Africa (Viljoen & Viljoen, 1969), are varieties of Mg-rich basalt and ultramafic lava that occur almost exclusively in Archean crust. The high Mg content (>18 wt% MgO) of these rocks (Nisbet et al., 1993; ...
... named after the Komati Formation in the Barberton Greenstone belt of the Kaapvaal craton, South Africa (Viljoen & Viljoen, 1969), are varieties of Mg-rich basalt and ultramafic lava that occur almost exclusively in Archean crust. The high Mg content (>18 wt% MgO) of these rocks (Nisbet et al., 1993; ...
Geological Society of America Bulletin
... sections should have deformed the accretionary prism or other parts of the crust in the shallow part of the subduction zone hanging wall (e.g., Taira, 2001). The first signs of this collision should define when the NE Philippine Sea plate began to be subducted beneath SW Japan. Understanding migrati ...
... sections should have deformed the accretionary prism or other parts of the crust in the shallow part of the subduction zone hanging wall (e.g., Taira, 2001). The first signs of this collision should define when the NE Philippine Sea plate began to be subducted beneath SW Japan. Understanding migrati ...
THE UPPER MANTLE AND ALKALIC MAGMAS
... mantle material comes dose to the thermal gradient within the earth (Fig. 1). However, along with the temperature effect, some phase effect like development of plagioclase (RINGWOOD 1962a, b), complex pyroxene (RINGWOOD 1962b), or amphibole (0XBURGH 1964) may be involved in lowering the seismic velo ...
... mantle material comes dose to the thermal gradient within the earth (Fig. 1). However, along with the temperature effect, some phase effect like development of plagioclase (RINGWOOD 1962a, b), complex pyroxene (RINGWOOD 1962b), or amphibole (0XBURGH 1964) may be involved in lowering the seismic velo ...
(2016). A joint local and teleseismic tomography study of
... In most tomographic studies investigating upper mantle velocities, the Vp and Vs anomaly magnitudes are dissimilar [e.g., Schmandt and Lin, 2014]. This is because Vp and Vs are affected differently by the three main factors that contribute to the velocity anomalies: temperature variations, the prese ...
... In most tomographic studies investigating upper mantle velocities, the Vp and Vs anomaly magnitudes are dissimilar [e.g., Schmandt and Lin, 2014]. This is because Vp and Vs are affected differently by the three main factors that contribute to the velocity anomalies: temperature variations, the prese ...
Paper 3.2 Mb pdf - Miles F Osmaston
... necessarily removing its underlying mantle too, the seismological evidence elsewhere, e.g., in the Andean “flat-slab” segments, north-central Peru and central Chile, already confirmed that the undercutting had proceeded to depths far into the mantle domain. This excluded gravitational action and sug ...
... necessarily removing its underlying mantle too, the seismological evidence elsewhere, e.g., in the Andean “flat-slab” segments, north-central Peru and central Chile, already confirmed that the undercutting had proceeded to depths far into the mantle domain. This excluded gravitational action and sug ...
as a PDF
... fuel large igneous provinces and generate volcanic chains. The plume hypothesis has influenced most fields of geochemistry, petrology, geodynamics and mantle evolution. The key axioms underlying the plume paradigm are identified: Axioms are self-evident truths and are seldom stated explicitly. When ...
... fuel large igneous provinces and generate volcanic chains. The plume hypothesis has influenced most fields of geochemistry, petrology, geodynamics and mantle evolution. The key axioms underlying the plume paradigm are identified: Axioms are self-evident truths and are seldom stated explicitly. When ...
Text - I2M Associates
... Magma passing through or incubating in the crust may interact with surrounding material. Crustal contamination of mafic magmas is expressed by having low Nb, Ta, Nb/Y and Ta/Y, and high concentrations of incompatible elements such as Rb, Ba, K, relative to other trace elements [6, 12, 16]. Negative ...
... Magma passing through or incubating in the crust may interact with surrounding material. Crustal contamination of mafic magmas is expressed by having low Nb, Ta, Nb/Y and Ta/Y, and high concentrations of incompatible elements such as Rb, Ba, K, relative to other trace elements [6, 12, 16]. Negative ...
Geology - Central Washington University Geological Sciences
... margins, but very different from most rifted margins, which display much more gradual transitions in crustal thickness. The geophysical data indicate an absence of synrift intrusive and volcanic rocks, underplated mafic rocks at the base of the crust, and abnormally thick oceanic crust adjacent to t ...
... margins, but very different from most rifted margins, which display much more gradual transitions in crustal thickness. The geophysical data indicate an absence of synrift intrusive and volcanic rocks, underplated mafic rocks at the base of the crust, and abnormally thick oceanic crust adjacent to t ...
accepted manuscript
... The EW-trending Xiaohuangshan ophiolite mélange (about 22 km long and 6 km wide) is situated in the Xiaohuangshan fault (TXF) (Fig. 3). A matrix of various schists contains about fifty exotic lenticular blocks that are mainly harzburgites and dunites, and a few olivine pyroxenites, pyroxenites, ande ...
... The EW-trending Xiaohuangshan ophiolite mélange (about 22 km long and 6 km wide) is situated in the Xiaohuangshan fault (TXF) (Fig. 3). A matrix of various schists contains about fifty exotic lenticular blocks that are mainly harzburgites and dunites, and a few olivine pyroxenites, pyroxenites, ande ...
38. EVIDENCE FOR DETACHMENT TECTONICS ON THE IBERIA
... confirmed that the basement ridge comprises serpentinized mantle rocks bounding the western end of the transition zone from oceanic to continental crust. Drilling also sampled serpentinites at Site 899, in the form of a mass-flow deposit, suggesting that serpentinized peridotite must form basement c ...
... confirmed that the basement ridge comprises serpentinized mantle rocks bounding the western end of the transition zone from oceanic to continental crust. Drilling also sampled serpentinites at Site 899, in the form of a mass-flow deposit, suggesting that serpentinized peridotite must form basement c ...
Seismic velocity structure and anisotropy of the Alaska subduction
... Previous studies of anisotropy in Alaska have been primarily from the analysis of SKS shear wave splitting [Christensen and Abers, 2010; Hanna and Long, 2012; Song and Kawakatsu, 2013; Perttu et al., 2014]. These studies have shown a striking transition in the observed fast-splitting direction at th ...
... Previous studies of anisotropy in Alaska have been primarily from the analysis of SKS shear wave splitting [Christensen and Abers, 2010; Hanna and Long, 2012; Song and Kawakatsu, 2013; Perttu et al., 2014]. These studies have shown a striking transition in the observed fast-splitting direction at th ...
Thermal and chemical structure at the bottom of the lower mantle
... chondritemantle. These are thought to be either primitive mantle residues (1), dense subducted slab components (2), products of chemical interactions between the core and mantle (3, 4), or dense melts perhaps as old as the Earth itself (5). The core-mantle boundary is a complex region that has been ...
... chondritemantle. These are thought to be either primitive mantle residues (1), dense subducted slab components (2), products of chemical interactions between the core and mantle (3, 4), or dense melts perhaps as old as the Earth itself (5). The core-mantle boundary is a complex region that has been ...
Kinematic Evolution of the Gulf of Mexico and Caribbean James
... Ecuador, having originated from subduction accretion complexes in western Mexico; 7) a KulaFarallon ridge segment is proposed to have generated at least part of the western Caribbean Plate in Aptian-Albian time, as part of the plate reorganisation associated with the polarity reversal; 8) B” plateau ...
... Ecuador, having originated from subduction accretion complexes in western Mexico; 7) a KulaFarallon ridge segment is proposed to have generated at least part of the western Caribbean Plate in Aptian-Albian time, as part of the plate reorganisation associated with the polarity reversal; 8) B” plateau ...
Chapter 10: Plate Tectonics
... new rock as older rock is eroded away. Seas were once found far inland from today’s ocean boundaries. This explains the existence of marine fossils far from the ocean’s shorelines. Examining these fossils gives scientists clues about what life was like in Earth’s past. ...
... new rock as older rock is eroded away. Seas were once found far inland from today’s ocean boundaries. This explains the existence of marine fossils far from the ocean’s shorelines. Examining these fossils gives scientists clues about what life was like in Earth’s past. ...
Origin and evolution of the lower crust in magmatic
... dense cumulates from the base of arc crust, foundering into less dense, underlying mantle peridotite, is likely, as supported by geochemical evidence from Talkeetna and Kohistan. Relamination of buoyant, subducting material—during sediment subduction, subduction erosion, arc-arc collision, and conti ...
... dense cumulates from the base of arc crust, foundering into less dense, underlying mantle peridotite, is likely, as supported by geochemical evidence from Talkeetna and Kohistan. Relamination of buoyant, subducting material—during sediment subduction, subduction erosion, arc-arc collision, and conti ...
Accurate focal depth determination of oceanic earthquakes using
... being due to depth-dependent stress and strain. Numerical modeling also suggests that the stress field within the lithosphere varies systematically and significantly with depth. The upper and the lower competent lithosphere are in horizontal deviatoric compression and tension, respectively (Parmentier ...
... being due to depth-dependent stress and strain. Numerical modeling also suggests that the stress field within the lithosphere varies systematically and significantly with depth. The upper and the lower competent lithosphere are in horizontal deviatoric compression and tension, respectively (Parmentier ...
Carbon Retention in Deeply Subducted Sedimentary Rocks
... shown for context. ...............................................................................................62 Appendix 6. Comparison of observed bulk δ13C values with values predicted for a closed-system model, where isotope ratios are controlled by exchange within the system rather than by e ...
... shown for context. ...............................................................................................62 Appendix 6. Comparison of observed bulk δ13C values with values predicted for a closed-system model, where isotope ratios are controlled by exchange within the system rather than by e ...
View - GFZpublic
... cal models on the origin of the Dead Sea basin that started in Miocene time, and (c) are consistent with typical xenolith‐derived geotherms for terranes of similar age and lithospheric thickness. Moho temperatures (at depths between 35 and 40 km) of the AS in pre‐Mio ...
... cal models on the origin of the Dead Sea basin that started in Miocene time, and (c) are consistent with typical xenolith‐derived geotherms for terranes of similar age and lithospheric thickness. Moho temperatures (at depths between 35 and 40 km) of the AS in pre‐Mio ...
Subduction kinematics and dynamic constraints
... reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower plates move relative to the mantle. Relative to a fixed point in the upper plate U, the transient subduction hinge H ca ...
... reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower plates move relative to the mantle. Relative to a fixed point in the upper plate U, the transient subduction hinge H ca ...
Subduction kinematics and dynamic constraints
... reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower plates move relative to the mantle. Relative to a fixed point in the upper plate U, the transient subduction hinge H ca ...
... reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower plates move relative to the mantle. Relative to a fixed point in the upper plate U, the transient subduction hinge H ca ...
Mechanisms of lithospheric extension at mid
... Department of Geological Sciences, Brown University, Providence, RI 02912, USA ...
... Department of Geological Sciences, Brown University, Providence, RI 02912, USA ...
- Wiley Online Library
... [1] Physical properties of the mantle lithosphere have a strong influence on the rifting processes and rifted structures. In particular, in context of rifting, two of these properties have been overlooked: (1) Mohr-Coulomb plasticity (localizing pressure dependent) may not be valid at mantle depths a ...
... [1] Physical properties of the mantle lithosphere have a strong influence on the rifting processes and rifted structures. In particular, in context of rifting, two of these properties have been overlooked: (1) Mohr-Coulomb plasticity (localizing pressure dependent) may not be valid at mantle depths a ...
PNAS-2014-Anderson-1..
... detail, they also violate the first and second laws of thermodynamics because they require noncooling boundaries and external sources of energy, material, and information (e.g., Maxwell demons); that is, the model planets are not closed, isolated, selforganizing systems living off of their own resou ...
... detail, they also violate the first and second laws of thermodynamics because they require noncooling boundaries and external sources of energy, material, and information (e.g., Maxwell demons); that is, the model planets are not closed, isolated, selforganizing systems living off of their own resou ...
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few mm to over ten cm per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr.