Why subduction zones are curved - Harvard John A. Paulson School
... of the downgoing slab. Although this analogy is commonly invoked as the explanation for subduction zone curvature [e.g., Turcotte and Schubert, 2002], observations of our planet do not show such a relationship between radius and dip [Tovish and Schubert, 1978; Bevis, 1986]. [4] Instead, four mechani ...
... of the downgoing slab. Although this analogy is commonly invoked as the explanation for subduction zone curvature [e.g., Turcotte and Schubert, 2002], observations of our planet do not show such a relationship between radius and dip [Tovish and Schubert, 1978; Bevis, 1986]. [4] Instead, four mechani ...
Extension of the continental lithosphere Introduction Background
... extended. The way in which they deform is dependent on their rheological properties, pressure, temperature and strain conditions. When the lithospheric is extended hot mantle (asthenosphere) rises to the base of the thinned lithosphere to maintain isostatic equilibrium. The lithosphere cools, contra ...
... extended. The way in which they deform is dependent on their rheological properties, pressure, temperature and strain conditions. When the lithospheric is extended hot mantle (asthenosphere) rises to the base of the thinned lithosphere to maintain isostatic equilibrium. The lithosphere cools, contra ...
Ellipsis Graphical User Interface - School of Geosciences
... extended. The way in which they deform is dependent on their rheological properties, pressure, temperature and strain conditions. When the lithospheric is extended hot mantle (asthenosphere) rises to the base of the thinned lithosphere to maintain isostatic equilibrium. The lithosphere cools, contra ...
... extended. The way in which they deform is dependent on their rheological properties, pressure, temperature and strain conditions. When the lithospheric is extended hot mantle (asthenosphere) rises to the base of the thinned lithosphere to maintain isostatic equilibrium. The lithosphere cools, contra ...
Glossary a - Teacher Friendly Guides
... Brachiopods look somewhat similar to the clams that you find at the beach today. Brachiopods and bivalves both have a pair of hinged shells (valves) to protect themselves while feeding. However, the soft parts of modern brachiopods tell us that they are completely unrelated to bivalves. Brachiopods ...
... Brachiopods look somewhat similar to the clams that you find at the beach today. Brachiopods and bivalves both have a pair of hinged shells (valves) to protect themselves while feeding. However, the soft parts of modern brachiopods tell us that they are completely unrelated to bivalves. Brachiopods ...
Vertical Movements - TU Delft OpenCourseWare
... Following thickness changes: • the crust has nothing more to say (neglecting erosion) •the lithospheric mantle will impose vertical movements; their magnitude depends on the amplitude of the thermal anomaly present at the end of thinning/thickening ...
... Following thickness changes: • the crust has nothing more to say (neglecting erosion) •the lithospheric mantle will impose vertical movements; their magnitude depends on the amplitude of the thermal anomaly present at the end of thinning/thickening ...
On the origin of the asthenosphere
... et al., 1981). The asthenosphere is considered to be the source region of mid-ocean ridge basalt, MORB (e.g., Hofmann, 1997; Stolper, 1980), and the production of MORB by partial melting is the largest volcanic activity on Earth. Consequently, there must be a close connection between mechanical weak ...
... et al., 1981). The asthenosphere is considered to be the source region of mid-ocean ridge basalt, MORB (e.g., Hofmann, 1997; Stolper, 1980), and the production of MORB by partial melting is the largest volcanic activity on Earth. Consequently, there must be a close connection between mechanical weak ...
Seismic character of volcanic activity at the ultraslow
... of swarm (85.58N, 888E). Errors shown are maximum value in error ellipse, because ellipse’s semimajor axes are oriented approximately along axis. Note that after April 15 there is slight southward shift of events toward valley floor. Because most of these later events occurred after U.S.S. Hawkbill ...
... of swarm (85.58N, 888E). Errors shown are maximum value in error ellipse, because ellipse’s semimajor axes are oriented approximately along axis. Note that after April 15 there is slight southward shift of events toward valley floor. Because most of these later events occurred after U.S.S. Hawkbill ...
PhD studentship in Earth Sciences School of Geography, Earth and
... Applicants must have at least a 2:1 degree in Earth Sciences (or a related subject) or equivalent qualification. Each studentship is supported for 3 years and includes full Home/EU tuition fees plus a stipend of £13,726 per annum. The studentship will only fully fund those applicants who are eligibl ...
... Applicants must have at least a 2:1 degree in Earth Sciences (or a related subject) or equivalent qualification. Each studentship is supported for 3 years and includes full Home/EU tuition fees plus a stipend of £13,726 per annum. The studentship will only fully fund those applicants who are eligibl ...
Influence of mantle dynamics on the topographic evolution of the
... state, and none of these attempts have won universal acceptance. Numerous causes of the Tibetan extension have been proposed: gravitational collapse driven by excess gravitational potential energy arising from the buoyant crustal root and the upwelled asthenosphere [Chen and Molnar, 1983; Dewey et a ...
... state, and none of these attempts have won universal acceptance. Numerous causes of the Tibetan extension have been proposed: gravitational collapse driven by excess gravitational potential energy arising from the buoyant crustal root and the upwelled asthenosphere [Chen and Molnar, 1983; Dewey et a ...
Title Page Photo grass of indecisiveness does not grow.” Kahlil Gibran (Brainquote.com)
... • Subduction trenches next to continents (“slab pull”) • Destructive boundary: Rock is destroyed via subduction • E.g., Andes Mountains and Cascade Range ...
... • Subduction trenches next to continents (“slab pull”) • Destructive boundary: Rock is destroyed via subduction • E.g., Andes Mountains and Cascade Range ...
PhD studentship in Earth Sciences School of Geography, Earth and
... Applicants must have at least a 2:1 degree in Earth Sciences (or a related subject) or equivalent qualification. Each studentship is supported for 3 years and includes full Home/EU tuition fees plus a stipend of £13,726 per annum. The studentship will only fully fund those applicants who are eligibl ...
... Applicants must have at least a 2:1 degree in Earth Sciences (or a related subject) or equivalent qualification. Each studentship is supported for 3 years and includes full Home/EU tuition fees plus a stipend of £13,726 per annum. The studentship will only fully fund those applicants who are eligibl ...
Evidence of low flexural rigidity and low viscosity lower continental... during continental break-up in the South China Sea
... southeast Asia is underlain by a region of cold, dense mantle asthenosphere formed by long-lived subduction in the western Pacific. This material is sinking deep into the upper mantle, causing dynamic subsidence, so that sediment-loading corrected depths to basement are as much as 1 km shallower tha ...
... southeast Asia is underlain by a region of cold, dense mantle asthenosphere formed by long-lived subduction in the western Pacific. This material is sinking deep into the upper mantle, causing dynamic subsidence, so that sediment-loading corrected depths to basement are as much as 1 km shallower tha ...
Norte Brasileira Ridge System, an example of natural component or
... In the Southern portion of the Amazonas Deep Fan, the bathymetric contours are displaced considerably to the east around the E-W segments of the Norte Brasileira Ridge. This displacement on the bathymetric lines shows the importance of the ridge as an expressive geomorphologic boundary on the BECM. ...
... In the Southern portion of the Amazonas Deep Fan, the bathymetric contours are displaced considerably to the east around the E-W segments of the Norte Brasileira Ridge. This displacement on the bathymetric lines shows the importance of the ridge as an expressive geomorphologic boundary on the BECM. ...
Insight into collision zone dynamics from topography
... Subduction zone topography is characterised by a long linear oceanic trench flanked by an outer rise on the subducting plate side and raised topography on the overriding plate (Melosh and Raefsky, 1980; Hager, 1984; Gephart, 1994). The origin of this topography is the result of the sum of dynamic fo ...
... Subduction zone topography is characterised by a long linear oceanic trench flanked by an outer rise on the subducting plate side and raised topography on the overriding plate (Melosh and Raefsky, 1980; Hager, 1984; Gephart, 1994). The origin of this topography is the result of the sum of dynamic fo ...
Introduction to Geology - Research at UVU
... 2. Formation of Magma and Volcanism a. Be sure to look at the following 3 handouts on this topic: i. ‘Volcanic Processes Summary’ - a page of text ii. ‘Volcanic Processes Summary Table’ -a table that relates magma formation to volcanic activity iii. ‘Magma Formation in the Earth’ - illustrations of ...
... 2. Formation of Magma and Volcanism a. Be sure to look at the following 3 handouts on this topic: i. ‘Volcanic Processes Summary’ - a page of text ii. ‘Volcanic Processes Summary Table’ -a table that relates magma formation to volcanic activity iii. ‘Magma Formation in the Earth’ - illustrations of ...
Generation of new continental crust by sublithospheric silicic
... 2. Taylor's andesite model: An overview on the origin of upper and lower continental crusts Besides the intriguing andesite average composition, an outstanding feature of the Earth's continental crust is the dichotomy between an upper layer of broadly granodioritic composition (SiO2 = 68 wt.%; MgO= ...
... 2. Taylor's andesite model: An overview on the origin of upper and lower continental crusts Besides the intriguing andesite average composition, an outstanding feature of the Earth's continental crust is the dichotomy between an upper layer of broadly granodioritic composition (SiO2 = 68 wt.%; MgO= ...
Glossary of Terms
... period of time) above an overpressured fluid reservoir when it ruptures and therefore intensely focuses fluid and/or magma flow. They tend to be broadly pipe-like to ribbon-like in geometry. Porphyry stocks and NiS hosting chonoliths are good examples. They are very important because they are the pr ...
... period of time) above an overpressured fluid reservoir when it ruptures and therefore intensely focuses fluid and/or magma flow. They tend to be broadly pipe-like to ribbon-like in geometry. Porphyry stocks and NiS hosting chonoliths are good examples. They are very important because they are the pr ...
Geology, 39
... The Nunatak eclogites occur in the Tasiusarsuaq terrane, central NAC, an area dominated by Late Archean TTG gneisses (Fig. 1A). Our eclogite Pb-Pb secondary isochron of 2.70 ± 0.29 Ga (Fig. 2C) overlaps the main peak in crustal growth of the central NAC between 2.9 and 2.7 Ga (Nutman et al., 2004; N ...
... The Nunatak eclogites occur in the Tasiusarsuaq terrane, central NAC, an area dominated by Late Archean TTG gneisses (Fig. 1A). Our eclogite Pb-Pb secondary isochron of 2.70 ± 0.29 Ga (Fig. 2C) overlaps the main peak in crustal growth of the central NAC between 2.9 and 2.7 Ga (Nutman et al., 2004; N ...
Formation of metamorphic core complexes in non-over - HAL-Insu
... ductile deformation with foliations during extension. A dome is underlined by the bended shape of foliation envelope within the lower crust where carries imprints of the extensional shear zone localized along the detachment and on top of the dome. Some well-known MCCs have been identified in the Aeg ...
... ductile deformation with foliations during extension. A dome is underlined by the bended shape of foliation envelope within the lower crust where carries imprints of the extensional shear zone localized along the detachment and on top of the dome. Some well-known MCCs have been identified in the Aeg ...
SXR339 Ancient Mountains ISBN0749258470
... familiar to geologists across the world as the Moine Thrust (Figure 1.1). Working in the south-eastern Highlands around Glen Clova (Figure 1.1), George Barrow founded the concepts of metamorphic zones and index minerals, which are now universally used to map belts of regional metamorphic rocks. Anot ...
... familiar to geologists across the world as the Moine Thrust (Figure 1.1). Working in the south-eastern Highlands around Glen Clova (Figure 1.1), George Barrow founded the concepts of metamorphic zones and index minerals, which are now universally used to map belts of regional metamorphic rocks. Anot ...
Americas, Asia will join to form a supercontinent
... Geological analysis suggest the current-day continents we know and love will drift together, forming a new supercontinent like ones that existed many millions of years ago. What’s not certain is where that supercontinent will be. The authors of a new Nature study suggest that the next supercontinent ...
... Geological analysis suggest the current-day continents we know and love will drift together, forming a new supercontinent like ones that existed many millions of years ago. What’s not certain is where that supercontinent will be. The authors of a new Nature study suggest that the next supercontinent ...
Seismic imaging of a hot upwelling beneath the British Isles
... The Iceland plume has had an important influence on vertical motions in the North Atlantic. The convecting mantle in this region contains a large-scale low-velocity seismic anomaly, which correlates with a long-wavelength gravity high and bathymetric feature. This suggests that an arm of plume mater ...
... The Iceland plume has had an important influence on vertical motions in the North Atlantic. The convecting mantle in this region contains a large-scale low-velocity seismic anomaly, which correlates with a long-wavelength gravity high and bathymetric feature. This suggests that an arm of plume mater ...
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.