Crustal Shortening and Extension in the Central Andes: Insights
... allow material flow along the strike of the mountain belt. The elastic parameters used in the calculations include the Young’s modulus (7x1010 MPa) and the Poisson’s ratio (0.25). Winkler springs are used to simulate the body forces induced by vertical displacement of density boundaries and the isos ...
... allow material flow along the strike of the mountain belt. The elastic parameters used in the calculations include the Young’s modulus (7x1010 MPa) and the Poisson’s ratio (0.25). Winkler springs are used to simulate the body forces induced by vertical displacement of density boundaries and the isos ...
Chapter 15. The Hard Rock Cafe
... If picrites are the parent for tholeiitic basalts, then roughly 30% melting is implied for generation fi-om a shallow peridotitic parent. If the parent is eclogitic, then similar temperatures would cause more extensive melting. Generation of basaltic magmas from an eclogitic parent does not require ...
... If picrites are the parent for tholeiitic basalts, then roughly 30% melting is implied for generation fi-om a shallow peridotitic parent. If the parent is eclogitic, then similar temperatures would cause more extensive melting. Generation of basaltic magmas from an eclogitic parent does not require ...
Shape and origin of the East-Alpine slab constrained by the
... During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity. More shallow slabs imaged below the Alpi ...
... During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity. More shallow slabs imaged below the Alpi ...
Subduction of the oceanic Hikurangi Plateau and its impact on the
... one of the most extreme volcanic events on Earth, characterized through eruption of vast amounts of lava in a geologically short period1. Oceanic LIPs either accrete and obduct, adding to the continental landmass2–4 or in rare cases recycle back into the Earth’s mantle via subduction. Known examples ...
... one of the most extreme volcanic events on Earth, characterized through eruption of vast amounts of lava in a geologically short period1. Oceanic LIPs either accrete and obduct, adding to the continental landmass2–4 or in rare cases recycle back into the Earth’s mantle via subduction. Known examples ...
Chapter F4
... The Composition of the Earth, continued • The Mantle is the layer of the Earth between the crust and the core. The mantle is much thicker than the crust and contains most of the Earth’s mass. • The crust is too thick to drill through, so scientists must draw conclusions about the composition and oth ...
... The Composition of the Earth, continued • The Mantle is the layer of the Earth between the crust and the core. The mantle is much thicker than the crust and contains most of the Earth’s mass. • The crust is too thick to drill through, so scientists must draw conclusions about the composition and oth ...
Heterogeneous sources for Pleistocene lavas of Marie Byrd Land
... from Mt. Avers and Recess Nunatak are basanites (Fig. 2). In the entire suite of lavas studied, SiO2 content ranges from 43 to 49 wt. %, and the MgO content ranges from 7 to 12 wt. %. With a few exceptions, the lavas within each volcanic center are homogeneous in their major and trace element compos ...
... from Mt. Avers and Recess Nunatak are basanites (Fig. 2). In the entire suite of lavas studied, SiO2 content ranges from 43 to 49 wt. %, and the MgO content ranges from 7 to 12 wt. %. With a few exceptions, the lavas within each volcanic center are homogeneous in their major and trace element compos ...
38. Tectonic Constraints on the Hotspot Formation of Ninetyeast Ridge
... the relative motion between the Indian and Australian plates (e.g., Royer and Sandwell, 1989). A second observation concerns the location and orientation of Ninetyeast Ridge relative to the adjacent fracture zones. Ninetyeast Ridge is slightly oblique relative to the fracture zone pattern, suggestin ...
... the relative motion between the Indian and Australian plates (e.g., Royer and Sandwell, 1989). A second observation concerns the location and orientation of Ninetyeast Ridge relative to the adjacent fracture zones. Ninetyeast Ridge is slightly oblique relative to the fracture zone pattern, suggestin ...
univERsity oF copEnhAGEn
... changes from lower crustal reflectivity to a reflection free part of the lower crust, which potentially may indicate the presence of underplated material. We include a wide range of processes into our definition of underplating, which is “addition of mafic magma to the lower crust and uppermost mantle a ...
... changes from lower crustal reflectivity to a reflection free part of the lower crust, which potentially may indicate the presence of underplated material. We include a wide range of processes into our definition of underplating, which is “addition of mafic magma to the lower crust and uppermost mantle a ...
pdf preprint - Institute of Geophysics and Planetary Physics
... 1989) and the geoid. A recent hybrid model—dynamic thinning —in which secondary convection in the ponding asthenosphere erodes the lithosphere downstream (Ribe, 2004), appears to find support in a recent seismic study (Li et al., 2004). The third model, compositional buoyancy, was suggested by Jorda ...
... 1989) and the geoid. A recent hybrid model—dynamic thinning —in which secondary convection in the ponding asthenosphere erodes the lithosphere downstream (Ribe, 2004), appears to find support in a recent seismic study (Li et al., 2004). The third model, compositional buoyancy, was suggested by Jorda ...
Moho and magmatic underplating
... changes from lower crustal reflectivity to a reflection free part of the lower crust, which potentially may indicate the presence of underplated material. We include a wide range of processes into our definition of underplating, which is “addition of mafic magma to the lower crust and uppermost mantle a ...
... changes from lower crustal reflectivity to a reflection free part of the lower crust, which potentially may indicate the presence of underplated material. We include a wide range of processes into our definition of underplating, which is “addition of mafic magma to the lower crust and uppermost mantle a ...
Traces of the crustal units and the upper-mantle
... 2002), with respect to the central point at the Lithuanian– Polish border (coordinates 23 ◦ E and 54 ◦ N) and the magnitude range from 5.5 to 7.2 (Fig. 5). The higher and lower values of the epicentral distance ensure that the first-observed arrivals are the direct P waves, and that they hit the tar ...
... 2002), with respect to the central point at the Lithuanian– Polish border (coordinates 23 ◦ E and 54 ◦ N) and the magnitude range from 5.5 to 7.2 (Fig. 5). The higher and lower values of the epicentral distance ensure that the first-observed arrivals are the direct P waves, and that they hit the tar ...
Imaging the lithospheric structure beneath the Indian continent
... Narmada-Son, Cambay, and Kutch rifts. However, in regions blanketed by the Deccan volcanic traps or sediments (e.g., beneath DVP: CB-DVP and Bundelkhand), the craton boundaries are not so well defined on the surface. The central portion of the Indian shield is mostly covered by thick (up to ~8 km) qu ...
... Narmada-Son, Cambay, and Kutch rifts. However, in regions blanketed by the Deccan volcanic traps or sediments (e.g., beneath DVP: CB-DVP and Bundelkhand), the craton boundaries are not so well defined on the surface. The central portion of the Indian shield is mostly covered by thick (up to ~8 km) qu ...
Sect. 7-3 and 7-4 Practice Quiz
... ____ 17. What can tectonic plates form when they converge? a. mid-ocean ridges c. sea floor b. mountains d. asthenosphere ____ 18. The southern portion of Pangaea that broke apart about 180 million years ago is known as a. Pangaea. c. Gondwana. b. Panthalassa. d. Laurasia. ____ 19. Continental-ocean ...
... ____ 17. What can tectonic plates form when they converge? a. mid-ocean ridges c. sea floor b. mountains d. asthenosphere ____ 18. The southern portion of Pangaea that broke apart about 180 million years ago is known as a. Pangaea. c. Gondwana. b. Panthalassa. d. Laurasia. ____ 19. Continental-ocean ...
Non-plume magmatism and tectonics during the opening of the
... tors, or a basalt wedge, along most of the central Atlantic continental margin. In the SE USA, strong sub-horizontal seismic reflectors of continental flood basalts of the South Georgia basin intersect or overlap the seaward-dipping reflectors (Oh et al., 1995). This very thick (to 25 km) basalt and ...
... tors, or a basalt wedge, along most of the central Atlantic continental margin. In the SE USA, strong sub-horizontal seismic reflectors of continental flood basalts of the South Georgia basin intersect or overlap the seaward-dipping reflectors (Oh et al., 1995). This very thick (to 25 km) basalt and ...
Introduction to EPS special section for the M7.1 and M6.4... in northeastern Japan Akira Hasegawa
... part of Miyagi prefecture and its surrounding areas; one is an intraslab earthquake with M7.1 that occurred on May 26 beneath the northern coast of the prefecture and the other is a shallow inland earthquake with M6.4 that occurred on July 26 in the northern part of the prefecture. After their occur ...
... part of Miyagi prefecture and its surrounding areas; one is an intraslab earthquake with M7.1 that occurred on May 26 beneath the northern coast of the prefecture and the other is a shallow inland earthquake with M6.4 that occurred on July 26 in the northern part of the prefecture. After their occur ...
Aftershock observation of the 2011 off the Pacific coast of... by using ocean bottom seismometer network
... from the deployed OBSs will contribute to the improvement of the hypocenter location in the source region. However, the region where the OBS networks were deployed was limited compared with the source region of the 2011 Tohoku Earthquake. To reveal precise aftershock distribution, an OBS network cov ...
... from the deployed OBSs will contribute to the improvement of the hypocenter location in the source region. However, the region where the OBS networks were deployed was limited compared with the source region of the 2011 Tohoku Earthquake. To reveal precise aftershock distribution, an OBS network cov ...
Magmatic processes at slow spreading ridges
... understanding melt generation, delivery and emplacement processes at slow spreading mid-ocean ridges, and the similarities and differences when compared with those at faster spreading ridges. 2 EX P ER I M EN T LO CATIO N A ND G EO L O GI C A L S ETT IN G The Reykjanes Ridge (Fig. 1) provided a suit ...
... understanding melt generation, delivery and emplacement processes at slow spreading mid-ocean ridges, and the similarities and differences when compared with those at faster spreading ridges. 2 EX P ER I M EN T LO CATIO N A ND G EO L O GI C A L S ETT IN G The Reykjanes Ridge (Fig. 1) provided a suit ...
Evidence for melting of garnet pyroxenite in the generation of
... Post-erosional lavas from Oahu and Kauai show large Os-isotopic variations, and extend to values more radiogenic than the most radiogenic shield stage lavas and far more radiogenic than any peridotites studied to date. lS7Os/~SSOs ranges from 0.142-0.160 in post-erosional lavas from Oahu, and from 0 ...
... Post-erosional lavas from Oahu and Kauai show large Os-isotopic variations, and extend to values more radiogenic than the most radiogenic shield stage lavas and far more radiogenic than any peridotites studied to date. lS7Os/~SSOs ranges from 0.142-0.160 in post-erosional lavas from Oahu, and from 0 ...
Terrestrial Heat Flow and the Mantle Convection Hypothesis
... pattern. The results are compared with observed heat flow. Subject to the assumptions of the models, the results suggest that sub-oceanic mantle convection currents, if they exist, are overlain by a layer 50- 100km thick which is stationary or moves much less rapidly. This appears to rule out the me ...
... pattern. The results are compared with observed heat flow. Subject to the assumptions of the models, the results suggest that sub-oceanic mantle convection currents, if they exist, are overlain by a layer 50- 100km thick which is stationary or moves much less rapidly. This appears to rule out the me ...
Wrench faults down to the asthenosphere
... crust. It is quite obvious that transcurrent faults generated at transform plate boundaries, like the San Andreas Fault in California or the Alpine fault in New Zealand crosscut the entire lithosphere. It is however less clear whether intracontinental strike-slip fault systems generated in active ma ...
... crust. It is quite obvious that transcurrent faults generated at transform plate boundaries, like the San Andreas Fault in California or the Alpine fault in New Zealand crosscut the entire lithosphere. It is however less clear whether intracontinental strike-slip fault systems generated in active ma ...
Scott Tarlow (), Department of Earth and
... of melting contours under and along the ridge axis. The vertical lines along the ridge distance from trench axis show different emplacements of the Hydrous/Anhydrous melting barrier along the ridge axis. C. Above is the relationship between relative melting area (unitless) and ridge distance from th ...
... of melting contours under and along the ridge axis. The vertical lines along the ridge distance from trench axis show different emplacements of the Hydrous/Anhydrous melting barrier along the ridge axis. C. Above is the relationship between relative melting area (unitless) and ridge distance from th ...
The Tectonic Framework of the Sumatran Subduction Zone
... The 100-km-wide Barisan Mountains, the backbone of Sumatra (Figure 2), include preTertiary rocks covered by Cenozoic volcanic rocks. The structural central graben led van Bemmelen (1949) to conclude it was a rift structure and that the Sumatran fault was dip-slip in nature. Subsequent work revealed ...
... The 100-km-wide Barisan Mountains, the backbone of Sumatra (Figure 2), include preTertiary rocks covered by Cenozoic volcanic rocks. The structural central graben led van Bemmelen (1949) to conclude it was a rift structure and that the Sumatran fault was dip-slip in nature. Subsequent work revealed ...
Table of Contents
... Partial support for this work was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement (CCLI) program underAward No. 0837185. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily ...
... Partial support for this work was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement (CCLI) program underAward No. 0837185. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily ...
Flat versus steep subduction: Contrasting modes for the formation
... subduction to collision. Slab inclination conditions for these two stages can be strongly dissimilar, which is taken into account by our models in a simplified manner: the initial slab dip angle corresponds to the early subduction stage and the final slab inclination characterizes the later collision ...
... subduction to collision. Slab inclination conditions for these two stages can be strongly dissimilar, which is taken into account by our models in a simplified manner: the initial slab dip angle corresponds to the early subduction stage and the final slab inclination characterizes the later collision ...
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.