Whole-mantle convection and the transition
... composed of MORB source materials, because it has so few radioactive heat sources; the remaining heat sources are thus thought to be hidden at greater depths in isolated reservoirs unsampled by mid-ocean ridges, but possibly sampled by plumes. In total, these and other observations suggest that the ...
... composed of MORB source materials, because it has so few radioactive heat sources; the remaining heat sources are thus thought to be hidden at greater depths in isolated reservoirs unsampled by mid-ocean ridges, but possibly sampled by plumes. In total, these and other observations suggest that the ...
Mantle Exhumation in an Early Paleozoic Passive Margin, Northern
... mantle during rifting of continental lithosphere at least 25 km thick subjected continental margin metasediments to conditions above the fluid-absent metapelite solidus. The contrasting strength of upper mantle and crustal lithologies during extension may explain the structural juxtaposition and bou ...
... mantle during rifting of continental lithosphere at least 25 km thick subjected continental margin metasediments to conditions above the fluid-absent metapelite solidus. The contrasting strength of upper mantle and crustal lithologies during extension may explain the structural juxtaposition and bou ...
Chemistry of Igneous Rocks
... (Lava is magma on the earth's surface.) Igneous rocks may be either extrusive if they form at the earth's surface (e.g., basalt) or intrusive if magma solidifies underground. Grpnitc, a coarse-grained rock composed predominantly of feldspar and quartz, is an intrusive rock. In fact, granite is the m ...
... (Lava is magma on the earth's surface.) Igneous rocks may be either extrusive if they form at the earth's surface (e.g., basalt) or intrusive if magma solidifies underground. Grpnitc, a coarse-grained rock composed predominantly of feldspar and quartz, is an intrusive rock. In fact, granite is the m ...
Mantle mixing - Earth and Environmental Sciences
... depleted and well-mixed upper mantle is separated by the seismically distinct 670 km boundary from a poorly mixed and enriched lower mantle. The mid-oceanic ridge basalts (MORB) originate from melting of the upper mantle, whereas ocean island basalts (OIB) derive from melting of material that is bro ...
... depleted and well-mixed upper mantle is separated by the seismically distinct 670 km boundary from a poorly mixed and enriched lower mantle. The mid-oceanic ridge basalts (MORB) originate from melting of the upper mantle, whereas ocean island basalts (OIB) derive from melting of material that is bro ...
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 ...
riDge-HotSpot iNteractioNS what mid-ocean ridges tell us
... The causes of hotspots and their depths of origin are the focus of an intense debate in the scientific community. The “plume” model hypothesizes rising of buoyant mantle plumes as the primary cause of prominent hotspots such as Iceland and Hawaii (Morgan, 1971). In contrast, the “anti-plume” school ...
... The causes of hotspots and their depths of origin are the focus of an intense debate in the scientific community. The “plume” model hypothesizes rising of buoyant mantle plumes as the primary cause of prominent hotspots such as Iceland and Hawaii (Morgan, 1971). In contrast, the “anti-plume” school ...
Paleozoic large igneous provinces of Northern Eurasia: Correlation
... V.A. Kravchinsky / Global and Planetary Change 86-87 (2012) 31–36 ...
... V.A. Kravchinsky / Global and Planetary Change 86-87 (2012) 31–36 ...
Cenozoic geological and plate tectonic evolution of SE Asia and the
... important intra-Paci®c events, such as voluminous Eocene boninite magmatism, seem to be older and require other causes. Indentation of Asia by India modi®ed the Asian continent, but there is little indication that India has been the driving force of tectonics in most of SE Asia. The most important C ...
... important intra-Paci®c events, such as voluminous Eocene boninite magmatism, seem to be older and require other causes. Indentation of Asia by India modi®ed the Asian continent, but there is little indication that India has been the driving force of tectonics in most of SE Asia. The most important C ...
Journal of Asian Earth Sciences 20 2002
... important intra-Paci®c events, such as voluminous Eocene boninite magmatism, seem to be older and require other causes. Indentation of Asia by India modi®ed the Asian continent, but there is little indication that India has been the driving force of tectonics in most of SE Asia. The most important C ...
... important intra-Paci®c events, such as voluminous Eocene boninite magmatism, seem to be older and require other causes. Indentation of Asia by India modi®ed the Asian continent, but there is little indication that India has been the driving force of tectonics in most of SE Asia. The most important C ...
2011 - University of Colorado Boulder
... but three higher resolution models are also computed (Table 2). Considering the important effects of seafloor age on the surface heat flux (e.g., Lister, 1977; Parsons, 1982), we quantify seafloor age distribution at different times in our models. Seafloor age calculation is only dependent on the plate ...
... but three higher resolution models are also computed (Table 2). Considering the important effects of seafloor age on the surface heat flux (e.g., Lister, 1977; Parsons, 1982), we quantify seafloor age distribution at different times in our models. Seafloor age calculation is only dependent on the plate ...
Mapping the evolving strain field during continental breakup from
... Afar triple junction (Fig. 1b). This, along with MER parallel ~NENNE oriented φ at stations located within Afar but west of the TGD lend support to structural measurements14 and kinematic models19 that suggest the TGD currently partitions most extension related to the separation of the Arabian Plate ...
... Afar triple junction (Fig. 1b). This, along with MER parallel ~NENNE oriented φ at stations located within Afar but west of the TGD lend support to structural measurements14 and kinematic models19 that suggest the TGD currently partitions most extension related to the separation of the Arabian Plate ...
Chapter 1- INTRODUCTION 1.1. Mantle Rocks This study is
... overlying the mantle that concentrates preferentially the incompatible elements derived by partial melting of the mantle during the Earth’s history. Seismology also recognizes a rigid conductive thermal boundary layer at the top of the convecting mantle that consist of both crust and that portion of ...
... overlying the mantle that concentrates preferentially the incompatible elements derived by partial melting of the mantle during the Earth’s history. Seismology also recognizes a rigid conductive thermal boundary layer at the top of the convecting mantle that consist of both crust and that portion of ...
metamorphism associated with extensional rifting of Gondwana
... of a high-temperature belt, generated by subduction processes beneath part of the Pelagonian realm. If they do record such processes, and the subsequent rapid uplift and cooling of an arc terrain as suggested, subduction must have begun before 85-80 Ma in order to subduct sufficient oceanic lithosph ...
... of a high-temperature belt, generated by subduction processes beneath part of the Pelagonian realm. If they do record such processes, and the subsequent rapid uplift and cooling of an arc terrain as suggested, subduction must have begun before 85-80 Ma in order to subduct sufficient oceanic lithosph ...
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... 9) Consider the tectonic plates on either side of an oceanic-ridge boundary. How are the plates moving with respect to the boundary? A) sliding along it B) falling into it C) moving away from it D) moving toward it Answer: C Explanation: ...
... 9) Consider the tectonic plates on either side of an oceanic-ridge boundary. How are the plates moving with respect to the boundary? A) sliding along it B) falling into it C) moving away from it D) moving toward it Answer: C Explanation: ...
This document in RTF format
... In 1993 a large seafloor volcanic eruption occurred along the CoAxial segment of the JdF, immediately to the north of Axial Volcano. This eruption was detected during its early stages by SOSUS observations (Fox et al., 1995), and subsequently studied intensively (e.g. special section in January 15, ...
... In 1993 a large seafloor volcanic eruption occurred along the CoAxial segment of the JdF, immediately to the north of Axial Volcano. This eruption was detected during its early stages by SOSUS observations (Fox et al., 1995), and subsequently studied intensively (e.g. special section in January 15, ...
Bathymetry of the Pacific Plate and its Implications
... depth or seafloor topography from the prediction of a cooling half-space model (HSC). Are the deviations caused entirely by mantle plumes or lithospheric reheating associated with sublithospheric small scale convection (SSC) or some other mechanisms? In this study, we analyzed the age- and geographi ...
... depth or seafloor topography from the prediction of a cooling half-space model (HSC). Are the deviations caused entirely by mantle plumes or lithospheric reheating associated with sublithospheric small scale convection (SSC) or some other mechanisms? In this study, we analyzed the age- and geographi ...
tethyan evolution of turkey: a plate tectonic approach
... in Turkey, the latter can be used as an independent check on the reconstructions. These unusually favourable conditions provide a good data base on which to tackle a variety of strati~phic~t~ctural problems that have so ...
... in Turkey, the latter can be used as an independent check on the reconstructions. These unusually favourable conditions provide a good data base on which to tackle a variety of strati~phic~t~ctural problems that have so ...
Volcanic hazards - School
... • An island arc DPM. • Two oceanic plates in collision. • Subduction of one tectonic plate occurs • Note that both plates are made of basalt. • Explosive eruption characterised by pyroclastic flows. • The 1995-97 eruption caused over half of the island to be abandoned due to pyroclastic flow risk ...
... • An island arc DPM. • Two oceanic plates in collision. • Subduction of one tectonic plate occurs • Note that both plates are made of basalt. • Explosive eruption characterised by pyroclastic flows. • The 1995-97 eruption caused over half of the island to be abandoned due to pyroclastic flow risk ...
Analysis of magnetotelluric data along the Lithoprobe seismic line 21
... the regional structure is 3D. Note that those limits are only indicative and could be affected by noise. Results for each site are presented in Fig. 3. µ and values larger than 0.1 are found for each MT site and for all the frequencies. This clearly indicates that the conductivity structure is at ...
... the regional structure is 3D. Note that those limits are only indicative and could be affected by noise. Results for each site are presented in Fig. 3. µ and values larger than 0.1 are found for each MT site and for all the frequencies. This clearly indicates that the conductivity structure is at ...
The importance of radiative heat transfer on superplumes in the
... reinforced by incorporating postglacial rebound analysis [15,16]. The presence of a viscosity hill in the lower mantle helps to facilitate the development of superplumes [6,11]. The changes of the spin state of iron [17] may also change the viscosity in the deep lower mantle. Very recently, a new st ...
... reinforced by incorporating postglacial rebound analysis [15,16]. The presence of a viscosity hill in the lower mantle helps to facilitate the development of superplumes [6,11]. The changes of the spin state of iron [17] may also change the viscosity in the deep lower mantle. Very recently, a new st ...
Seismic structure of the crust and uppermost mantle of the Capricorn
... stations were deployed for approximately 1 year (mid 2006–2007) during which time 70 earthquakes were recorded at each station with a suitable signal to noise ratio for receiver function analysis and hence the S wavespeed profiles of the crust and uppermost mantle beneath each recording station are d ...
... stations were deployed for approximately 1 year (mid 2006–2007) during which time 70 earthquakes were recorded at each station with a suitable signal to noise ratio for receiver function analysis and hence the S wavespeed profiles of the crust and uppermost mantle beneath each recording station are d ...
Volledig proefschrift
... of the overriding plate towards the subducting plate by some external force, or ‘lithospheric doubling’ (Vlaar, 1983). This process may provide a means to subduct buoyant material and may result in shallow subduction with a very low to zero subduction angle, as observed today below parts of the Ande ...
... of the overriding plate towards the subducting plate by some external force, or ‘lithospheric doubling’ (Vlaar, 1983). This process may provide a means to subduct buoyant material and may result in shallow subduction with a very low to zero subduction angle, as observed today below parts of the Ande ...
The global range of subduction zone thermal structures from
... evaluated by van Keken et al. (2002) and Gerya et al. (2002). In general, younger (warmer) subducting plates possess higher predicted temperatures at a given pressure than do older plates (Fig. 3A), and slower convergence leads to higher temperatures for P < 2 GPa than does faster convergence (Fig. ...
... evaluated by van Keken et al. (2002) and Gerya et al. (2002). In general, younger (warmer) subducting plates possess higher predicted temperatures at a given pressure than do older plates (Fig. 3A), and slower convergence leads to higher temperatures for P < 2 GPa than does faster convergence (Fig. ...
Plate tectonics
Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός ""pertaining to building"") is a scientific theory that describes the large-scale motion of Earth's lithosphere. This theoretical model builds on the concept of continental drift which was developed during the first few decades of the 20th century. The geoscientific community accepted the theory after the concepts of seafloor spreading were later developed in the late 1950s and early 1960s.The lithosphere, which is the rigid outermost shell of a planet (on Earth, the crust and upper mantle), is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) propose gradual shrinking (contraction) or gradual expansion of the globe.Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.