Leseane_okstate_0664M_13248
... world [Feucht et al., 2013; Jones et al., 2013]. Our current understanding and models of geodynamic processes explaining rift initiation are therefore strongly influenced by observations from the more evolved rift systems. Estimates of the lithospheric thickness in the southern part of Africa sugges ...
... world [Feucht et al., 2013; Jones et al., 2013]. Our current understanding and models of geodynamic processes explaining rift initiation are therefore strongly influenced by observations from the more evolved rift systems. Estimates of the lithospheric thickness in the southern part of Africa sugges ...
Electrical conductivity as a constraint on lower mantle thermo
... mantle, or from the recycling of oceanic crust (MORB). Calculations based on mineral physics database suggest that LLSVPs are better explained by material enriched in iron and silicate than by recycled oceanic crust, which would require temperatures in excess of 1500 K relative to average temperatur ...
... mantle, or from the recycling of oceanic crust (MORB). Calculations based on mineral physics database suggest that LLSVPs are better explained by material enriched in iron and silicate than by recycled oceanic crust, which would require temperatures in excess of 1500 K relative to average temperatur ...
Back Arc Extension in the Okinawa Trough
... with normal faulting of the initially adjacent Ryukyu nonvolcanic arc and the Taiwan-Sinzi folded belt, corresponds to the first rifting phase. The timing of rifting is supported by the presence of marine sedimentsof corresponding age drilled in the northern Okinawa Trough. The rifting occurred afte ...
... with normal faulting of the initially adjacent Ryukyu nonvolcanic arc and the Taiwan-Sinzi folded belt, corresponds to the first rifting phase. The timing of rifting is supported by the presence of marine sedimentsof corresponding age drilled in the northern Okinawa Trough. The rifting occurred afte ...
Relationship between seismic and gravity anomalies at
... model of the crust-mantle transition, favoring a thin crust/hot mantle seismic structure. Tryggvason (1964) also favored a thin crust (10-15km) and a partially molten mantle. However, Angenheister et al. (1980) reinterepreted the RRISP shots and indicated a crustal thickness of 30km under Iceland. B ...
... model of the crust-mantle transition, favoring a thin crust/hot mantle seismic structure. Tryggvason (1964) also favored a thin crust (10-15km) and a partially molten mantle. However, Angenheister et al. (1980) reinterepreted the RRISP shots and indicated a crustal thickness of 30km under Iceland. B ...
Global Correlations of Ocean Ridge Basalt Chemistry with Axial
... MgO^depth correlation is less significant partly because of the use of samples with MgO 47 wt% only. All these correlations are statistically significant at the 495% confidence level. SiO2 and the minor oxides MnO and P2O5 do not show systematic variation vs ridge axial depth. However, Fig. 5a shows ...
... MgO^depth correlation is less significant partly because of the use of samples with MgO 47 wt% only. All these correlations are statistically significant at the 495% confidence level. SiO2 and the minor oxides MnO and P2O5 do not show systematic variation vs ridge axial depth. However, Fig. 5a shows ...
Determination of fault friction from reactivation of
... Outer-slope faults begin to accommodate extension in the subducting plate in the outer rise at distances of 45–75 km from the trench axis (Masson, 1991; Kobayashi et al., 1998; Massell, 2002; Ranero et al., 2003). Reactivated abyssal-hill faults are identified by their orientation, which is parallel ...
... Outer-slope faults begin to accommodate extension in the subducting plate in the outer rise at distances of 45–75 km from the trench axis (Masson, 1991; Kobayashi et al., 1998; Massell, 2002; Ranero et al., 2003). Reactivated abyssal-hill faults are identified by their orientation, which is parallel ...
A normalised seawater strontium isotope curve: possible
... seafloor spreading rates, which determine ocean crust production, have exhibited only limited variation over the past 150 Myr (Rowley, 2002; Cogné and Humler, 2006), attempts have been made to relate the marine carbonate-based seawater 87 Sr/86 Sr curve to changes in globally integrated chemical we ...
... seafloor spreading rates, which determine ocean crust production, have exhibited only limited variation over the past 150 Myr (Rowley, 2002; Cogné and Humler, 2006), attempts have been made to relate the marine carbonate-based seawater 87 Sr/86 Sr curve to changes in globally integrated chemical we ...
Three-dimensional seismic anisotropy in the crust and uppermost
... coherent patterns in most stations, indicating an SN orientation for the anisotropy. Based on a good fit for the observed anisotropy with the major lineaments on the surface (faults, ridges, and elongated geological structures), the authors proposed that the observed strong anisotropy is caused by cr ...
... coherent patterns in most stations, indicating an SN orientation for the anisotropy. Based on a good fit for the observed anisotropy with the major lineaments on the surface (faults, ridges, and elongated geological structures), the authors proposed that the observed strong anisotropy is caused by cr ...
Tectonic stress field of the continental United States
... regionally consistent orientations persist throughout the seismic "brittle" upper crust. Stress provinces are defined on the basis of uniform stress orientations and relative stress magnitudes (style of faulting). The sources of stress for all the major stress provinces are believed to be linked eit ...
... regionally consistent orientations persist throughout the seismic "brittle" upper crust. Stress provinces are defined on the basis of uniform stress orientations and relative stress magnitudes (style of faulting). The sources of stress for all the major stress provinces are believed to be linked eit ...
lithosphere 2006 - Helsingin yliopisto
... References of Lithosphere Symposia Publications Pesonen, L.J., Korja, A. and Hjelt, S.-E., 2000 (Eds.). Lithosphere 2000 - A Symposium on the Structure, Composition and Evolution of the Lithosphere in Finland. Programme and Extended Abstracts, Espoo, Finland, October 4-5, 2000. Institute of Seismolo ...
... References of Lithosphere Symposia Publications Pesonen, L.J., Korja, A. and Hjelt, S.-E., 2000 (Eds.). Lithosphere 2000 - A Symposium on the Structure, Composition and Evolution of the Lithosphere in Finland. Programme and Extended Abstracts, Espoo, Finland, October 4-5, 2000. Institute of Seismolo ...
1 Imaging the transition from flat to normal subduction: Variations in
... proposed as an explanation for the lateral extent of the Peruvian flat slab (Gutscher et al., 1999b). ...
... proposed as an explanation for the lateral extent of the Peruvian flat slab (Gutscher et al., 1999b). ...
Slide 1 - Global Heat Flow Database
... Locations of active volcanoes (red triangles) and heat flow sites in South America. Light blue sites are in low-angle subduction area; purple sites are in the high angle subduction area. ...
... Locations of active volcanoes (red triangles) and heat flow sites in South America. Light blue sites are in low-angle subduction area; purple sites are in the high angle subduction area. ...
The Caribbean-North America-Cocos Triple Junction
... [7] The change of angle between the plate motion vector and the azimuth of the arcuate plate margin fault was discussed to explain extension eastward and shortening westward close to the transform zone (model E, Figure 3) [Burkart and Self, 1985; DeMets et al., 2000; Rogers and Mann, 2007]. Numerica ...
... [7] The change of angle between the plate motion vector and the azimuth of the arcuate plate margin fault was discussed to explain extension eastward and shortening westward close to the transform zone (model E, Figure 3) [Burkart and Self, 1985; DeMets et al., 2000; Rogers and Mann, 2007]. Numerica ...
to the PDF file. - CURVE
... Figure 14: Sample 10-BV-29 in outcrop (A) and hand sample (B) part o f the Eastern suite of FCM. (A) Shows the outcrop as bedded and very sheared, striking easterly and dipping 10°N whereas (B) shows an average abundance of vesicles present in most samples of this suite.............................. ...
... Figure 14: Sample 10-BV-29 in outcrop (A) and hand sample (B) part o f the Eastern suite of FCM. (A) Shows the outcrop as bedded and very sheared, striking easterly and dipping 10°N whereas (B) shows an average abundance of vesicles present in most samples of this suite.............................. ...
Ocean Drilling Program Initial Reports Volume 160
... at Site 966. The sedimentary structures and the nature of the benthic foraminifers indicate a bathyal, relatively deep-water environment, with pelagic carbonate deposition in a regionally stable tectonic setting, free of input from sediment gravity flows (e.g., calciturbidites). During Late Cretaceo ...
... at Site 966. The sedimentary structures and the nature of the benthic foraminifers indicate a bathyal, relatively deep-water environment, with pelagic carbonate deposition in a regionally stable tectonic setting, free of input from sediment gravity flows (e.g., calciturbidites). During Late Cretaceo ...
PDF version - Western Washington University
... In linking the formation of island arcs to the formation of continental crust, a few central points about continental crust are important to consider. Continental crust is high-standing and thick, with an average “andesitic” bulk composition (Rudnick and Gao 2003; Taylor and McLennan 1985, and refer ...
... In linking the formation of island arcs to the formation of continental crust, a few central points about continental crust are important to consider. Continental crust is high-standing and thick, with an average “andesitic” bulk composition (Rudnick and Gao 2003; Taylor and McLennan 1985, and refer ...
Low seismic velocity layers in the Earth`s crust beneath Eastern
... Analysis of teleseismic receiver functions at digital stations along the Bratsk – Irkutsk – Ulanbaatar – Undurshil profile suggests that low-velocity layers in the Earth’s crust exist not only beneath the Baikal rift zone, where such a layer was found earlier by Deep Seismic Sounding (DSS), but also ...
... Analysis of teleseismic receiver functions at digital stations along the Bratsk – Irkutsk – Ulanbaatar – Undurshil profile suggests that low-velocity layers in the Earth’s crust exist not only beneath the Baikal rift zone, where such a layer was found earlier by Deep Seismic Sounding (DSS), but also ...
Moho map of South America from receiver functions and surface
... et al., 2000; Beurlen, 1970] and there are indications for current tectonic activity [Riccomini and Assumpção, 1999]. [3] The tectonic forces responsible for the observed differences likely also left an imprint beneath the surface. Understanding these subsurface structures may therefore help unravel ...
... et al., 2000; Beurlen, 1970] and there are indications for current tectonic activity [Riccomini and Assumpção, 1999]. [3] The tectonic forces responsible for the observed differences likely also left an imprint beneath the surface. Understanding these subsurface structures may therefore help unravel ...
SXR339 Ancient Mountains ISBN0749258470
... oceanic crust onto the Laurentian margin. The ophiolite is interpreted as an eroded remnant of a much larger ophiolite-bearing thrust nappe. The Tyrone inlier (Figure 5.2) comprises gabbros, a sheeted dyke complex and pillow basalts, and is interpreted as an ophiolite fragment. The complex has been ...
... oceanic crust onto the Laurentian margin. The ophiolite is interpreted as an eroded remnant of a much larger ophiolite-bearing thrust nappe. The Tyrone inlier (Figure 5.2) comprises gabbros, a sheeted dyke complex and pillow basalts, and is interpreted as an ophiolite fragment. The complex has been ...
2.01 Cosmochemical Estimates of Mantle Composition
... substantial radial mixing that must have occurred when the terrestrial planets formed. In current models of planet formation, the Earth is made by collisions of a hundred or more Moon- to Marssized embryos, small planets that formed within a million years from local feeding zones. The growth of the ...
... substantial radial mixing that must have occurred when the terrestrial planets formed. In current models of planet formation, the Earth is made by collisions of a hundred or more Moon- to Marssized embryos, small planets that formed within a million years from local feeding zones. The growth of the ...
Asymmetric plume-ridge interaction around Iceland: The Kolbeinsey
... [1] We present the results of a seismic refraction experiment that constrains crustal structure and thickness along 225 km of the Kolbeinsey Ridge and Tjörnes Fracture Zone and thus quantifies the influence of the Iceland hot spot on melt flux at the spreading center north of Iceland. North of the ...
... [1] We present the results of a seismic refraction experiment that constrains crustal structure and thickness along 225 km of the Kolbeinsey Ridge and Tjörnes Fracture Zone and thus quantifies the influence of the Iceland hot spot on melt flux at the spreading center north of Iceland. North of the ...
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.