Zircon Behaviour in Deeply Subducted Rocks
... Metamorphic zircon found in HP rocks has usually been interpreted as forming at the pressure peak, i.e. the maximum subduction depth, which in most cases also corresponds to the temperature peak. However, zircon in HP rocks can in fact form over a wide range of conditions, from prograde subduction t ...
... Metamorphic zircon found in HP rocks has usually been interpreted as forming at the pressure peak, i.e. the maximum subduction depth, which in most cases also corresponds to the temperature peak. However, zircon in HP rocks can in fact form over a wide range of conditions, from prograde subduction t ...
Origin of Archean subcontinental lithospheric mantle: Some
... In this model, advocated originally by Helmstaedt and Schulze (1989), the subcontinental lithospheric mantle is proposed to have grown through the accretion of slabs of oceanic lithosphere. The idea is that portions of lithosphere that originally formed at a mid-ocean ridge were thrust one beneath a ...
... In this model, advocated originally by Helmstaedt and Schulze (1989), the subcontinental lithospheric mantle is proposed to have grown through the accretion of slabs of oceanic lithosphere. The idea is that portions of lithosphere that originally formed at a mid-ocean ridge were thrust one beneath a ...
Physics and Chemistry of Deep Continental Crust
... in Mongolia, both far from plate boundaries) as well as the magmatism and enhanced surface heat flow often associated with these anomalous uplifts. Bird (1979) may have been the first to highlight that these nonplate tectonic geologic phenomena may result from the growth of small-scale density insta ...
... in Mongolia, both far from plate boundaries) as well as the magmatism and enhanced surface heat flow often associated with these anomalous uplifts. Bird (1979) may have been the first to highlight that these nonplate tectonic geologic phenomena may result from the growth of small-scale density insta ...
Thematic Article A bathymetric overview of the Mariana forearc
... found where sediment ¯ux to the trench is high. Conversely, forearc basement is exposed where the sediment supply is low; Le Pichon et al. (1993) state that no active accretionary wedge exists where the average trench ®ll is less than 1 km. High-sediment-supply forearcs are characterized by thick se ...
... found where sediment ¯ux to the trench is high. Conversely, forearc basement is exposed where the sediment supply is low; Le Pichon et al. (1993) state that no active accretionary wedge exists where the average trench ®ll is less than 1 km. High-sediment-supply forearcs are characterized by thick se ...
An enhanced image of the PamirHindu Kush
... created by the collision of the Indian and Eurasian plates (Fig. 1). The tectonic evolution of the region can broadly be divided into three stages (Windley 1988). The ¢rst stage saw the northward migration of several plates from Gondwanaland and the formation of magmatic arcs, with the closure of Te ...
... created by the collision of the Indian and Eurasian plates (Fig. 1). The tectonic evolution of the region can broadly be divided into three stages (Windley 1988). The ¢rst stage saw the northward migration of several plates from Gondwanaland and the formation of magmatic arcs, with the closure of Te ...
workshop report
... we observe on the surface of the earth has been deformed, metamorphosed, and otherwise processed perhaps several times from its creation in subduction zones to the present. It’s impossible to imagine a wild tuna fish from opening a can of processed tuna; the same might be said about juvenile versus ...
... we observe on the surface of the earth has been deformed, metamorphosed, and otherwise processed perhaps several times from its creation in subduction zones to the present. It’s impossible to imagine a wild tuna fish from opening a can of processed tuna; the same might be said about juvenile versus ...
Weakness of the lower continental crust: a condition for
... often only indirect evidence for mobilized asthenosphere is available. England and Houseman (1989) mention three key indicators: (1) onset of mafic volcanism, (2) a regional change of the stress system to extension, which is related to (3) regional uplift. The presence of all three indicators provid ...
... often only indirect evidence for mobilized asthenosphere is available. England and Houseman (1989) mention three key indicators: (1) onset of mafic volcanism, (2) a regional change of the stress system to extension, which is related to (3) regional uplift. The presence of all three indicators provid ...
Trace Element and Isotope Geochemistry of the Volcanic Rocks of
... are higher and Nd ratios are lower than those of the IHS. The the Lesser Antillean arc (Fig. 1), which formed along IDS is also characterized by high dla0 values, up to 7-6 in the eastern edge of the Caribbean Plate as a result of clinopyroxene. The Sr and Pb isotope ratios are too high, and the sub ...
... are higher and Nd ratios are lower than those of the IHS. The the Lesser Antillean arc (Fig. 1), which formed along IDS is also characterized by high dla0 values, up to 7-6 in the eastern edge of the Caribbean Plate as a result of clinopyroxene. The Sr and Pb isotope ratios are too high, and the sub ...
Three-dimensional crustal structure of the Mariana island arc from
... [5] The IBM subduction zone, along which Late Cretaceous to Early Jurassic ocean crust of the Pacific plate descends beneath the Philippine Sea plate, extends 2800 km from Guam in the south to Japan in the north, where the northern end of the volcanic arc is colliding with the main Japanese island o ...
... [5] The IBM subduction zone, along which Late Cretaceous to Early Jurassic ocean crust of the Pacific plate descends beneath the Philippine Sea plate, extends 2800 km from Guam in the south to Japan in the north, where the northern end of the volcanic arc is colliding with the main Japanese island o ...
Possible density segregation of subducted oceanic
... The viscosity ratio between the ambient mantle and the serpentinite layer, ηo / ηS, is probably at least 10 because the addition of ppm levels of water to nominally anhydrous minerals can decrease viscosities by a factor of 10 or more [38], hence the presence of enough water to stabilize hydrous min ...
... The viscosity ratio between the ambient mantle and the serpentinite layer, ηo / ηS, is probably at least 10 because the addition of ppm levels of water to nominally anhydrous minerals can decrease viscosities by a factor of 10 or more [38], hence the presence of enough water to stabilize hydrous min ...
The Seismic Structure of Island Arc Crust
... 2004). In addition, some island arcs such as Japan have been built on, or contain some component of, remnant continental crust, and as such they cannot be considered pure island arc systems. In this paper, I will contrast the crustal structure of non-extended and extended island arc systems, includi ...
... 2004). In addition, some island arcs such as Japan have been built on, or contain some component of, remnant continental crust, and as such they cannot be considered pure island arc systems. In this paper, I will contrast the crustal structure of non-extended and extended island arc systems, includi ...
univERsity oF copEnhAGEn
... The North Atlantic margins are the classic places where significant underplating related to rifting and break-up processes has been observed. Ray tracing modelling of a profile (Fig. 2) across the margin at Hatton Bank identifies an up-to 14 km thick zone of unusually high seismic P-wave velocity above ...
... The North Atlantic margins are the classic places where significant underplating related to rifting and break-up processes has been observed. Ray tracing modelling of a profile (Fig. 2) across the margin at Hatton Bank identifies an up-to 14 km thick zone of unusually high seismic P-wave velocity above ...
Moho and magmatic underplating
... The North Atlantic margins are the classic places where significant underplating related to rifting and break-up processes has been observed. Ray tracing modelling of a profile (Fig. 2) across the margin at Hatton Bank identifies an up-to 14 km thick zone of unusually high seismic P-wave velocity above ...
... The North Atlantic margins are the classic places where significant underplating related to rifting and break-up processes has been observed. Ray tracing modelling of a profile (Fig. 2) across the margin at Hatton Bank identifies an up-to 14 km thick zone of unusually high seismic P-wave velocity above ...
Kerguelen Hotspot Magma Output since 130 Ma
... oceanic plateaux predict initially voluminous magmatism over a relatively short period of 1–2 Myr, followed by steady-state magma output at much lower rates (Richards et al., 1989; Duncan & Richards, 1991). Furthermore, massive magma output from hotspots is commonly, but not always associated in spa ...
... oceanic plateaux predict initially voluminous magmatism over a relatively short period of 1–2 Myr, followed by steady-state magma output at much lower rates (Richards et al., 1989; Duncan & Richards, 1991). Furthermore, massive magma output from hotspots is commonly, but not always associated in spa ...
Weakening of the subduction interface and its effects on surface
... the volcanic arc. In order to fit heat flow observations, a number of authors have concluded that a trenchward part of the mantle wedge beneath the forearc must be stagnant [Furukawa and Uyeda, 1989; Furukawa, 1993; Peacock and Wang, 1999; van Keken et al., 2002; Currie et al., 2004a]. [4] Another l ...
... the volcanic arc. In order to fit heat flow observations, a number of authors have concluded that a trenchward part of the mantle wedge beneath the forearc must be stagnant [Furukawa and Uyeda, 1989; Furukawa, 1993; Peacock and Wang, 1999; van Keken et al., 2002; Currie et al., 2004a]. [4] Another l ...
Isostasy, flexure, and dynamic topography
... are frequently not available. Isostatic factors controlling lithospheric buoyancy are frequently uncertain and nonisostatic factors, such as lithospheric bending towards subduction zones and dynamic topography, are hard to distinguish. The question discussed here is whether a set of simple rules tha ...
... are frequently not available. Isostatic factors controlling lithospheric buoyancy are frequently uncertain and nonisostatic factors, such as lithospheric bending towards subduction zones and dynamic topography, are hard to distinguish. The question discussed here is whether a set of simple rules tha ...
Subducting slabs: Jellyfishes in the Earth`s mantle
... cube. Free slip is assumed on all boundaries. The experiment is initiated by placing a vertical (unless otherwise specified) plate of length, l = 0.066 (∼182 km) and thickness h = 0.03 (∼83 km) in the mantle between depths of 0.03 and 0.096 (∼83 km to 264 km, Figure 1a). [8] To ensure that the plate ...
... cube. Free slip is assumed on all boundaries. The experiment is initiated by placing a vertical (unless otherwise specified) plate of length, l = 0.066 (∼182 km) and thickness h = 0.03 (∼83 km) in the mantle between depths of 0.03 and 0.096 (∼83 km to 264 km, Figure 1a). [8] To ensure that the plate ...
V. C. Summer Nuclear Station, Units 2 and 3 COL Application
... Ridge consists of an assemblage of Middle Proterozoic crystalline continental (Grenville) basement rock nonconformably overlain by Late Proterozoic to Early Paleozoic rift-facies sedimentary rock (Reference 279). The basement consists of various types of gneisses, amphibolite, gabbroic and volcanic ...
... Ridge consists of an assemblage of Middle Proterozoic crystalline continental (Grenville) basement rock nonconformably overlain by Late Proterozoic to Early Paleozoic rift-facies sedimentary rock (Reference 279). The basement consists of various types of gneisses, amphibolite, gabbroic and volcanic ...
DEEP STRUCTURE AND GEOPHYSICAL PROCESSES BENEATH
... Julian for supplying computer programs which were subsequently modified; Drs. Jorge Mendiguren, Don Weidner and Professor Sean Solomon for helpful hints on reading seismograms; Dr. D. Joe Andrews for much advice on numerical and mathematical matters; Al Smith, Professors Richard Naylor, Seiya Uyeda ...
... Julian for supplying computer programs which were subsequently modified; Drs. Jorge Mendiguren, Don Weidner and Professor Sean Solomon for helpful hints on reading seismograms; Dr. D. Joe Andrews for much advice on numerical and mathematical matters; Al Smith, Professors Richard Naylor, Seiya Uyeda ...
Types of Metamorphism
... - where?: Localized at interaction of hot, largely aqueous fluids (from igneous source) with country rocks. - Similar to regional ocean-floor metamorphism - the aqueous hydrothermal fluids usually transported via fractures and shear zones at some distance either near or far from their source - The y ...
... - where?: Localized at interaction of hot, largely aqueous fluids (from igneous source) with country rocks. - Similar to regional ocean-floor metamorphism - the aqueous hydrothermal fluids usually transported via fractures and shear zones at some distance either near or far from their source - The y ...
Incipient shortening of a passive margin: the mechanical roles of
... adjustments. Models with various strength profiles represented oceanic lithospheres of different ages. The continental lithosphere reacted to an applied boundary velocity according to the strength and density of oceanic lithosphere. Where oceanic lithosphere was stronger and heavier than continental ...
... adjustments. Models with various strength profiles represented oceanic lithospheres of different ages. The continental lithosphere reacted to an applied boundary velocity according to the strength and density of oceanic lithosphere. Where oceanic lithosphere was stronger and heavier than continental ...
Geodynamic models of Cordilleran orogens
... Cordilleran orogens, such as the central Andes, form above subduction zones, and their evolution depends on both continental shortening and oceanic plate subduction processes, including arc magmatism and granitoid batholith formation. Arc and batholith magma compositions are consistent with partial ...
... Cordilleran orogens, such as the central Andes, form above subduction zones, and their evolution depends on both continental shortening and oceanic plate subduction processes, including arc magmatism and granitoid batholith formation. Arc and batholith magma compositions are consistent with partial ...
Plate dynamics, mantle structure and tectonic evolution of the
... 1.1 Short overview of the tectonic history of the Caribbean plate The Caribbean plate (Figure 1.1) is an actively deforming region between two major subduction zones: the Lesser Antilles subduction zone in the east and the Central America subduction zone in the west. The northern boundary with the N ...
... 1.1 Short overview of the tectonic history of the Caribbean plate The Caribbean plate (Figure 1.1) is an actively deforming region between two major subduction zones: the Lesser Antilles subduction zone in the east and the Central America subduction zone in the west. The northern boundary with the N ...
Present-day crustal motion within the Tibetan Plateau inferred from
... ‘‘glacier-like flow’’ zone which starts at somewhere between the middle and western plateau, goes clockwise around the Eastern Himalayan Syntaxis (EHS), and ends at the southeast corner of the plateau with a fan-like front. The deformation feature of the southern plateau, especially the emergence of ...
... ‘‘glacier-like flow’’ zone which starts at somewhere between the middle and western plateau, goes clockwise around the Eastern Himalayan Syntaxis (EHS), and ends at the southeast corner of the plateau with a fan-like front. The deformation feature of the southern plateau, especially the emergence of ...
Ascent of the ultrahigh-pressure Western Gneiss Region, Norway.
... lower-pressure terranes is in danger of becoming a paradigm (e.g., Ernst, 1999), in spite of only local field evidence supporting this interpretation. Only two of the giant UHP massifs are well known: The UHP rocks of the Kokchetav Massif are exposed within a thin, 1–2 km thick unit (Kaneko et al., ...
... lower-pressure terranes is in danger of becoming a paradigm (e.g., Ernst, 1999), in spite of only local field evidence supporting this interpretation. Only two of the giant UHP massifs are well known: The UHP rocks of the Kokchetav Massif are exposed within a thin, 1–2 km thick unit (Kaneko et al., ...