PDF
... [14] Mantle lithosphere is widely accepted to be slightly more dense than underlying asthenosphere, by ⬃1–2%, and it is this excess density that powers subduction zones and moves the plates [Davies, 1999]. Density excess increases as the lithosphere ages and thickens, and the observed asymmetry in l ...
... [14] Mantle lithosphere is widely accepted to be slightly more dense than underlying asthenosphere, by ⬃1–2%, and it is this excess density that powers subduction zones and moves the plates [Davies, 1999]. Density excess increases as the lithosphere ages and thickens, and the observed asymmetry in l ...
subduction zones
... [14] Mantle lithosphere is widely accepted to be slightly more dense than underlying asthenosphere, by ⬃1–2%, and it is this excess density that powers subduction zones and moves the plates [Davies, 1999]. Density excess increases as the lithosphere ages and thickens, and the observed asymmetry in l ...
... [14] Mantle lithosphere is widely accepted to be slightly more dense than underlying asthenosphere, by ⬃1–2%, and it is this excess density that powers subduction zones and moves the plates [Davies, 1999]. Density excess increases as the lithosphere ages and thickens, and the observed asymmetry in l ...
Deformation in the asthenospheric mantle beneath the Carpathian
... less than 20∘ and delay time error is mainly between 0.1 and 0.3 s (Table S1). Most of the stations depict a robust pattern of fast orientation (e.g., CBP3I, TARL, and CBP2F) that is mainly oriented NW-SE (hereafter major pattern). Figure 2b shows a histogram of the distribution of the fast azimuth ...
... less than 20∘ and delay time error is mainly between 0.1 and 0.3 s (Table S1). Most of the stations depict a robust pattern of fast orientation (e.g., CBP3I, TARL, and CBP2F) that is mainly oriented NW-SE (hereafter major pattern). Figure 2b shows a histogram of the distribution of the fast azimuth ...
Seismologia ja maan rakenne 762321A Seismology and
... Montagner and Kennett (1996); Bottom: PREM (Dziewonski and Anderson, 1981). - and : P- and S-wave velocity, respectively; - density, Q and Q = Q - “quality factor” Q for P ...
... Montagner and Kennett (1996); Bottom: PREM (Dziewonski and Anderson, 1981). - and : P- and S-wave velocity, respectively; - density, Q and Q = Q - “quality factor” Q for P ...
THESIS SEAFLOOR SPREADING IN THE EASTERN GULF OF
... the Upper Triassic-Lower Jurassic Huizachal redbeds essentially coincides spatially with the Permian-Triassic plutonic belt, and they occur in a 400-km-long and 50- km-wide zone ...
... the Upper Triassic-Lower Jurassic Huizachal redbeds essentially coincides spatially with the Permian-Triassic plutonic belt, and they occur in a 400-km-long and 50- km-wide zone ...
Composition of the Oceanic Crust - DukeSpace
... 4.21). Thus, in contrast to continental crust, oceanic crust is ephemeral: its mean age is about 60 Ma (Cogné et al., 2006) and it is nowhere older than about 167 Ma (Koppers et al., 2003), except in the Eastern Mediterranean where in situ crust as old as 270 Ma may be preserved (Müller et al., 20 ...
... 4.21). Thus, in contrast to continental crust, oceanic crust is ephemeral: its mean age is about 60 Ma (Cogné et al., 2006) and it is nowhere older than about 167 Ma (Koppers et al., 2003), except in the Eastern Mediterranean where in situ crust as old as 270 Ma may be preserved (Müller et al., 20 ...
4. The Relief of the Oceanic Basement and the Structure of the Front of
... The most striking feature in the seismic sections is the sequence of undeformed reflectors lying beneath the deformed zone (Chase and Bunce, 1969; Marlow et al., 1974; Peter and Westbrook, 1976). The top of this sequence has been interpreted as a décollement surface (Biju-Duval et al., 1978; Westbro ...
... The most striking feature in the seismic sections is the sequence of undeformed reflectors lying beneath the deformed zone (Chase and Bunce, 1969; Marlow et al., 1974; Peter and Westbrook, 1976). The top of this sequence has been interpreted as a décollement surface (Biju-Duval et al., 1978; Westbro ...
No Slide Title
... • In 1924, the great Russian biochemist, – A.I. Oparin, postulated that life originated – when Earth’s atmosphere had little or no free oxygen ...
... • In 1924, the great Russian biochemist, – A.I. Oparin, postulated that life originated – when Earth’s atmosphere had little or no free oxygen ...
No Slide Title
... – the rocks were compressed, deformed, – cut by faults, – and intruded by rising magma ...
... – the rocks were compressed, deformed, – cut by faults, – and intruded by rising magma ...
Origins of the lower crustal reflectivity in the L¨utzow
... Bay region (Kanao, 1997). The shear wave velocity models derived consist of 32 layers with thickness of either 1 or 2 km, depending on the expected large velocity discontinuity in the starting model after Ikami et al. (1984). That is, we have set the thickness of 1 km for the topmost surface layer a ...
... Bay region (Kanao, 1997). The shear wave velocity models derived consist of 32 layers with thickness of either 1 or 2 km, depending on the expected large velocity discontinuity in the starting model after Ikami et al. (1984). That is, we have set the thickness of 1 km for the topmost surface layer a ...
Seismic modeling study of the Earth`s deep crust
... geological interfaces. A first estimation of the seismic velocities is obtained from prior geological and geophysical information of the study area. The P-wave seismic-velocity values are taken from various sources (e.g., Ponziani et al., 1995) and considering the data published by Christensen (1989 ...
... geological interfaces. A first estimation of the seismic velocities is obtained from prior geological and geophysical information of the study area. The P-wave seismic-velocity values are taken from various sources (e.g., Ponziani et al., 1995) and considering the data published by Christensen (1989 ...
ISCI 2001 Final Exam Review
... minerals they are made of (basalt vs granitic) 2. Distinguish between the lithosphere and asthenosphere parts of the mantle. 3. Distinguish between the outer and inner core and the elements and minerals are made of. 4. Know that there are 8 plates and know what the plates are made of. 5. Know that t ...
... minerals they are made of (basalt vs granitic) 2. Distinguish between the lithosphere and asthenosphere parts of the mantle. 3. Distinguish between the outer and inner core and the elements and minerals are made of. 4. Know that there are 8 plates and know what the plates are made of. 5. Know that t ...
Supercontinents, mantle dynamics and plate
... superplume genesis. The widely held view that the volume of continental crust has increased over time has been challenged in recent works and current models propose that plate tectonics creates and destroys Earth's continental crust with more crust being destroyed than created. The creation–destruct ...
... superplume genesis. The widely held view that the volume of continental crust has increased over time has been challenged in recent works and current models propose that plate tectonics creates and destroys Earth's continental crust with more crust being destroyed than created. The creation–destruct ...
Geo-neutrinos and Earth`s interior
... on the grounds of available geochemical and/or geophysical data, one cannot exclude that radioactivity in the present Earth is enough to account for even the highest estimate of terrestrial heat flow. An unambiguous and observationally based determination of the radiogenic heat production would prov ...
... on the grounds of available geochemical and/or geophysical data, one cannot exclude that radioactivity in the present Earth is enough to account for even the highest estimate of terrestrial heat flow. An unambiguous and observationally based determination of the radiogenic heat production would prov ...
PDF - University of Arizona
... Figure 6 shows the CCP stacks of four E-W and N-S profiles. The arrivals from Moho can be clearly identified from these cross-sections. Figure 7 shows a map of the depth to Moho determined from the SRF stacks. The Moho depth is fairly consistent throughout the entire region as shown in the crustal ...
... Figure 6 shows the CCP stacks of four E-W and N-S profiles. The arrivals from Moho can be clearly identified from these cross-sections. Figure 7 shows a map of the depth to Moho determined from the SRF stacks. The Moho depth is fairly consistent throughout the entire region as shown in the crustal ...
Crust recycling in the sources of two parallel volcanic chains in
... from Rudnick and Gao (2003). At 130 Ma, 60% partial melting decreases the Th/La ratio of the recycled LCC (eclogite) from 0.150 to 0.036, and its U/La ratio decreases from 0.025 to 0.010. At 20 Ma, the residue of recycled LCC (eclogite) remelted (15% proportions of melts extracted), and these melts ...
... from Rudnick and Gao (2003). At 130 Ma, 60% partial melting decreases the Th/La ratio of the recycled LCC (eclogite) from 0.150 to 0.036, and its U/La ratio decreases from 0.025 to 0.010. At 20 Ma, the residue of recycled LCC (eclogite) remelted (15% proportions of melts extracted), and these melts ...
Dynamic Earth: crustal and mantle heterogeneity
... suggesting deep mantle origins has been challenged by Anderson (2000, 2001). The gradation of tones in the lower mantle is meant to suggest the main heterogeneity regimes. Slab penetration occurs down to about 1200 km, but somewhat unevenly across the globe (Niu & Kawakatsu 1997). Below 2100 km, the ...
... suggesting deep mantle origins has been challenged by Anderson (2000, 2001). The gradation of tones in the lower mantle is meant to suggest the main heterogeneity regimes. Slab penetration occurs down to about 1200 km, but somewhat unevenly across the globe (Niu & Kawakatsu 1997). Below 2100 km, the ...
Full-text PDF (final published version)
... leading to pronounced chemical and isotopic heterogeneity. Firstly, portions of oceanic crust (ocean islands as well as some mid-ocean ridges) show geochemical signatures that cannot be explained as remnants of un-differentiated mantle (also called bulk silicate Earth) or its simple melt depletion ( ...
... leading to pronounced chemical and isotopic heterogeneity. Firstly, portions of oceanic crust (ocean islands as well as some mid-ocean ridges) show geochemical signatures that cannot be explained as remnants of un-differentiated mantle (also called bulk silicate Earth) or its simple melt depletion ( ...
Homework of 9/19
... that erupt basaltic magma also occur on both oceanic and continental crust. —The source of basaltic magma, therefore, must be the mantle. —Everywhere along the midocean ridges, volcanoes erupt basaltic magma. —Some large basaltic volcanoes are not located along midocean ridges. The Hawaiian volcanic ...
... that erupt basaltic magma also occur on both oceanic and continental crust. —The source of basaltic magma, therefore, must be the mantle. —Everywhere along the midocean ridges, volcanoes erupt basaltic magma. —Some large basaltic volcanoes are not located along midocean ridges. The Hawaiian volcanic ...
Indentation of a continent with a built
... when magmas rising from the subducting oceanic plate arc weld the accreted prism of sediments into continental crust in either island or cordilleran arcs (Mitchel and Garson, 1976). Open-ocean subduction may be punctuated by the docking of small terrains with large continents. However, large persist ...
... when magmas rising from the subducting oceanic plate arc weld the accreted prism of sediments into continental crust in either island or cordilleran arcs (Mitchel and Garson, 1976). Open-ocean subduction may be punctuated by the docking of small terrains with large continents. However, large persist ...
Earthquake slip on oceanic transform faults
... (solid lines, 20 samples per second), are corrected for the instrument response and ®ltered between 1 and 150 s. The dashed lines are the synthetics. The stations are chosen to allow comparison between earthquakes on each transform and between transforms. The dates, depths and magnitudes are given. ...
... (solid lines, 20 samples per second), are corrected for the instrument response and ®ltered between 1 and 150 s. The dashed lines are the synthetics. The stations are chosen to allow comparison between earthquakes on each transform and between transforms. The dates, depths and magnitudes are given. ...
Softening of the subcontinental lithospheric mantle by
... Thus, upwelling hot asthenosphere and diffuse porous flow of asthenospheric melts was accompanied by a temperature increase in the affected lithospheric mantle that brought it above the liquidus of percolating melts and close to the dry peridotite solidus, i.e., practically to asthenospheric tempera ...
... Thus, upwelling hot asthenosphere and diffuse porous flow of asthenospheric melts was accompanied by a temperature increase in the affected lithospheric mantle that brought it above the liquidus of percolating melts and close to the dry peridotite solidus, i.e., practically to asthenospheric tempera ...
Satellite gravity anomalies and crustal features of the
... in Table 1. The seismic sequence stratigraphic boundary Oligocene (O) and structural unconformities of upper Miocene (A), lower Pliocene (AA) and upper Pleistocene (B) and seafloor are correlated to ODP Leg 116 results10,11,22. ...
... in Table 1. The seismic sequence stratigraphic boundary Oligocene (O) and structural unconformities of upper Miocene (A), lower Pliocene (AA) and upper Pleistocene (B) and seafloor are correlated to ODP Leg 116 results10,11,22. ...
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.