The Laramide Orogeny: What Were the Driving Forces?
... American plate must have been driven by ridgepush from the Atlantic spreading-center or by basal drag caused by mantle convection. Basal drag is not considered to be an important factor in driving plate motions (e.g. Stüwe, 2002); this model, therefore, requires that horizontal normal compressive st ...
... American plate must have been driven by ridgepush from the Atlantic spreading-center or by basal drag caused by mantle convection. Basal drag is not considered to be an important factor in driving plate motions (e.g. Stüwe, 2002); this model, therefore, requires that horizontal normal compressive st ...
The Laramide Orogeny - University of Nevada, Reno
... American plate must have been driven by ridgepush from the Atlantic spreading-center or by basal drag caused by mantle convection. Basal drag is not considered to be an important factor in driving plate motions (e.g. Stüwe, 2002); this model, therefore, requires that horizontal normal compressive st ...
... American plate must have been driven by ridgepush from the Atlantic spreading-center or by basal drag caused by mantle convection. Basal drag is not considered to be an important factor in driving plate motions (e.g. Stüwe, 2002); this model, therefore, requires that horizontal normal compressive st ...
subduction dynamics and mantle tomography beneath japan
... slabs. Gray dots shown in cross-sections represent the Pacific and Philippine Sea slab seismicity. Dashed black curves in cross-sections represent the 410-km and 660-km seismic discontinuities. Continuous black curves shown on the map represent the location of the three cross-sections. 2.3 Numerical ...
... slabs. Gray dots shown in cross-sections represent the Pacific and Philippine Sea slab seismicity. Dashed black curves in cross-sections represent the 410-km and 660-km seismic discontinuities. Continuous black curves shown on the map represent the location of the three cross-sections. 2.3 Numerical ...
nature ano evolution of the subcontinental mantle lithosphere below
... Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicate that these inelusions are derived from the subcontinental mande lithosphere. The conditions of equilibrati ...
... Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicate that these inelusions are derived from the subcontinental mande lithosphere. The conditions of equilibrati ...
Paper
... from the shelf down to the abyssal plain without any rise. This configuration is due to the very active contouritic processes that have controlled the Southern passive volcanic Argentine Margin sedimentation and morphology along time to reach the present-day configuration. The term continental rise ...
... from the shelf down to the abyssal plain without any rise. This configuration is due to the very active contouritic processes that have controlled the Southern passive volcanic Argentine Margin sedimentation and morphology along time to reach the present-day configuration. The term continental rise ...
Chapter 6. The Shape of the Earth
... to 1400 km. Although these have been interpreted as the scales of convection and thermal variations they could also be caused by density variations due to chemistry and, perhaps, partial melt content, in the upper mantle . Several of the spectral peaks are similar in wavelength to chemical variation ...
... to 1400 km. Although these have been interpreted as the scales of convection and thermal variations they could also be caused by density variations due to chemistry and, perhaps, partial melt content, in the upper mantle . Several of the spectral peaks are similar in wavelength to chemical variation ...
1 The tectonic agenda
... • The deforming plate boundaries are very narrow in comparison to the lateral dimensions of the individual plates. Plate tectonicscan only provide a useful description if the number of plates remains small; if large numbers of plates are needed to describe the behaviour of the lithosphere, then the ...
... • The deforming plate boundaries are very narrow in comparison to the lateral dimensions of the individual plates. Plate tectonicscan only provide a useful description if the number of plates remains small; if large numbers of plates are needed to describe the behaviour of the lithosphere, then the ...
A narrowly spaced double-seismic zone in the subducting Nazca plate
... bands of seismicity (Figure 3a). The distribution of depths, calculated from the top of the upper seismic layer, indicates a distance between the two layers of 8 – 10 km (Figure 3b). The top of the upper seismic layer correlates with a dipping reflector (Nazca-reflector) that was imaged at somewhat ...
... bands of seismicity (Figure 3a). The distribution of depths, calculated from the top of the upper seismic layer, indicates a distance between the two layers of 8 – 10 km (Figure 3b). The top of the upper seismic layer correlates with a dipping reflector (Nazca-reflector) that was imaged at somewhat ...
Baltica upside down: A new plate tectonic model for Rodinia and the
... and has represented one of the mainstays of pre-Mesozoic plate reconstructions. Current models intimately link early Paleozoic or late Precambrian opening of the Iapetus Ocean to breakup of the Rodinia supercontinent (e.g., Hoffman, 1991; Torsvik et al., 1996; Dalziel et al., 2000). The paleogeograp ...
... and has represented one of the mainstays of pre-Mesozoic plate reconstructions. Current models intimately link early Paleozoic or late Precambrian opening of the Iapetus Ocean to breakup of the Rodinia supercontinent (e.g., Hoffman, 1991; Torsvik et al., 1996; Dalziel et al., 2000). The paleogeograp ...
Processes of Magma Evolution and Magmatic Suites
... regions where lithospheric extension has created intra-plate rifts. The African Rift Valley is a prime example. There are a number of more exotic primary magmas, usually highly alkaline primary magmas, which are very small in volume but have a paramount petrological and geodynamic importance. These ...
... regions where lithospheric extension has created intra-plate rifts. The African Rift Valley is a prime example. There are a number of more exotic primary magmas, usually highly alkaline primary magmas, which are very small in volume but have a paramount petrological and geodynamic importance. These ...
Drift Theory and Plate Tectonics: A Case of Embedding
... astronomy or that of the phlogiston theory of combustion by the oxygen theory are usually presented as clear examples of replacement. Unlike other sorts of diachronic developments that clearly exhibit either a continuous character or a discontinuous one, crystallization occurs when continuous and di ...
... astronomy or that of the phlogiston theory of combustion by the oxygen theory are usually presented as clear examples of replacement. Unlike other sorts of diachronic developments that clearly exhibit either a continuous character or a discontinuous one, crystallization occurs when continuous and di ...
No plume beneath Iceland
... activity variable, low amplitude (few 100 m) & localised. • 54 Ma uplift associated with igneous activity distant from proposed plume, high amplitude (up to 1 km) & widespread. • Time between onset and peak uplift for both igneous phases probably << 1 Myr. • Uplift history complex & not satisfactori ...
... activity variable, low amplitude (few 100 m) & localised. • 54 Ma uplift associated with igneous activity distant from proposed plume, high amplitude (up to 1 km) & widespread. • Time between onset and peak uplift for both igneous phases probably << 1 Myr. • Uplift history complex & not satisfactori ...
Southwest U.S. Region Mountain
... • Several fragments into which it has been split are clearly visible • To the west of the fragments, the hot mantle upwelling under the Basin and Range Province and the upwelling under the Southern Rocky Mountains are visible • The high oceanic plateau fragment 300 miles under the Great Plains that ...
... • Several fragments into which it has been split are clearly visible • To the west of the fragments, the hot mantle upwelling under the Basin and Range Province and the upwelling under the Southern Rocky Mountains are visible • The high oceanic plateau fragment 300 miles under the Great Plains that ...
Crust-mantle structures and Neogene
... These movements could not produce the opening of the Tyrrhenian basin, or the building of the Apennines (Anderson and Jackson, 1987a). However, the Apenninic thrust sheets underwent large displacements from west to east with associated counterclockwise rotations of up to 40°. During the last 10 Ma, ...
... These movements could not produce the opening of the Tyrrhenian basin, or the building of the Apennines (Anderson and Jackson, 1987a). However, the Apenninic thrust sheets underwent large displacements from west to east with associated counterclockwise rotations of up to 40°. During the last 10 Ma, ...
ferrari answers
... 3. What is the reason for the abrupt change for flat to steep subduction in the Cocos plate? Why is the Cocos plate more difficult to subduct than the Rivera plate? There is no evidence that the Cocos slab beneath the central Mexico is more buoyant than to the east or than the Rivera slab. This is i ...
... 3. What is the reason for the abrupt change for flat to steep subduction in the Cocos plate? Why is the Cocos plate more difficult to subduct than the Rivera plate? There is no evidence that the Cocos slab beneath the central Mexico is more buoyant than to the east or than the Rivera slab. This is i ...
the earth`s mantle elasticity and constitution
... change of composition, involving a change of intrinsic density; or (2) a change to phases of higher density, or (3) changes of both of these kinds. A phase change of olivine from its familiar orthorhombic symmetry to a cubiC, spinel structure has been suggested by Bernal and Jeffreys: this seemed pa ...
... change of composition, involving a change of intrinsic density; or (2) a change to phases of higher density, or (3) changes of both of these kinds. A phase change of olivine from its familiar orthorhombic symmetry to a cubiC, spinel structure has been suggested by Bernal and Jeffreys: this seemed pa ...
Document
... (IBM) arc that aim at comprehensive understanding of arc evolution and continental crust formation. We propose to drill a deep hole that penetrates through a complete sequence of intra-oceanic arc upper crust and into the in situ middle crust that may be a nucleus of continental crust. The average c ...
... (IBM) arc that aim at comprehensive understanding of arc evolution and continental crust formation. We propose to drill a deep hole that penetrates through a complete sequence of intra-oceanic arc upper crust and into the in situ middle crust that may be a nucleus of continental crust. The average c ...
PDF File - Tulane University
... the experimental charge could possibly react with the container in which it was placed. Thus, the choice of the container or capsule, as it is called, is very important. Perhaps the best in this regard is gold. Gold remains relative inert at high temperatures, and thus does not appear to react with ...
... the experimental charge could possibly react with the container in which it was placed. Thus, the choice of the container or capsule, as it is called, is very important. Perhaps the best in this regard is gold. Gold remains relative inert at high temperatures, and thus does not appear to react with ...
Mantle-drip magmatism beneath the Altiplano
... Pyroxenites inferred to have sourced the plateau magmas described here were most likely clinopyroxenites with or without garnet, which typically complement large arc systems at depth (Ducea and Saleeby, 1998). Rare earth element (REE) patterns suggest that garnet may have been present in the pyroxen ...
... Pyroxenites inferred to have sourced the plateau magmas described here were most likely clinopyroxenites with or without garnet, which typically complement large arc systems at depth (Ducea and Saleeby, 1998). Rare earth element (REE) patterns suggest that garnet may have been present in the pyroxen ...
Geology - Geostud
... values were determined on the basis of Poisson’s ratios between 0.25 and 0.3 for various lithologies (Christensen, 1996). To obtain realistic synthetic waveforms, each computed waveform is convolved with the observed vertical component. The real ambient noise measured 100–5 s before Pwave arrival wa ...
... values were determined on the basis of Poisson’s ratios between 0.25 and 0.3 for various lithologies (Christensen, 1996). To obtain realistic synthetic waveforms, each computed waveform is convolved with the observed vertical component. The real ambient noise measured 100–5 s before Pwave arrival wa ...
Precambrian Research Geochemical and numerical constraints
... rocks with different petrogenetic processes. Furthermore, Smithies (2000) pointed out that most early Archean and many Neoarchean TTGs lack mantle signatures thus showing no evidence for slab melt–mantle interactions and, therefore, cannot be attributed to modern-style subduction. Therefore, the ter ...
... rocks with different petrogenetic processes. Furthermore, Smithies (2000) pointed out that most early Archean and many Neoarchean TTGs lack mantle signatures thus showing no evidence for slab melt–mantle interactions and, therefore, cannot be attributed to modern-style subduction. Therefore, the ter ...
Sum4_Flatslabs
... the subducting plate to supplement the buoyancy factor. This was not a part of his models and is therefore a possibility. 2. There may be other possibilities not discussed by van Hunen. We discussed the possibility that there may be other mechanisms, yet undetermined, ...
... the subducting plate to supplement the buoyancy factor. This was not a part of his models and is therefore a possibility. 2. There may be other possibilities not discussed by van Hunen. We discussed the possibility that there may be other mechanisms, yet undetermined, ...
pdf file - Pacific Northwest Geodetic Array
... Please send your comments and/or additions to this draft! RATIONALE Subduction zones are the most dynamic tectonic environments on earth. The fastest relative plate motions and the highest mass fluxes of sediment, magma, and related fluids into the continental crust and mantle occur at subduction zo ...
... Please send your comments and/or additions to this draft! RATIONALE Subduction zones are the most dynamic tectonic environments on earth. The fastest relative plate motions and the highest mass fluxes of sediment, magma, and related fluids into the continental crust and mantle occur at subduction zo ...
The Yellowstone Hotspot: Plume or Not?
... slab material, exploits a zone of weakness in the slab, or breaks through the slab (e.g., Obrebski et al., 2010). Alternatively, an upwelling plume might slip around the exposed southern edge of the subducting Juan de Fuca slab, or be drawn in from the east during westward trench retreat and Farallo ...
... slab material, exploits a zone of weakness in the slab, or breaks through the slab (e.g., Obrebski et al., 2010). Alternatively, an upwelling plume might slip around the exposed southern edge of the subducting Juan de Fuca slab, or be drawn in from the east during westward trench retreat and Farallo ...
Supercontinent
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as P.F. Hoffman (1999) use the term ""supercontinent"" to mean ""a clustering of nearly all continents"". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.