Bivergent thrust wedges surrounding oceanic island arcs: Insight
... faulting in an island arc may, therefore, be evidence that the arc is relatively rigid. The rigidity of an island arc may arise from its mafic composition and has implications for seismic-hazard analysis. INTRODUCTION It has long been recognized that convergence in continent-continent collisions and ...
... faulting in an island arc may, therefore, be evidence that the arc is relatively rigid. The rigidity of an island arc may arise from its mafic composition and has implications for seismic-hazard analysis. INTRODUCTION It has long been recognized that convergence in continent-continent collisions and ...
The Hawaiian SWELL Pilot Experiment
... Regional body wave tomography using temporary deployments of broadband arrays have come a long way to image plume–like features on land (e.g. Wolfe et al, 1997; Keyser et al., 2002; Schutt and Humphreys, 2004) but similar studies at Hawaii are extremely limited, due to the nearly linear alignment of ...
... Regional body wave tomography using temporary deployments of broadband arrays have come a long way to image plume–like features on land (e.g. Wolfe et al, 1997; Keyser et al., 2002; Schutt and Humphreys, 2004) but similar studies at Hawaii are extremely limited, due to the nearly linear alignment of ...
PDF (Chapter 9. The Source Region)
... would crystallize as eclogite. Eclogite is a dense clinopyroxene-garnet-rich rock that is the high-pressure form of MORB and picrite, the postulated direct parent of MORB. The parent reservoir, in addition, probably contains orthopyroxene and olivine, the other major minerals of the mantle. The com ...
... would crystallize as eclogite. Eclogite is a dense clinopyroxene-garnet-rich rock that is the high-pressure form of MORB and picrite, the postulated direct parent of MORB. The parent reservoir, in addition, probably contains orthopyroxene and olivine, the other major minerals of the mantle. The com ...
Upper mantle and lithospheric heterogeneities in central
... to the mantle transition zone. Receiver functions provide valuable information on structural features, which are important for the resolution of European lithospheric dynamics. Moho depths vary from less than 25 km in extensional areas in central Europe to more than 50 km at stations in eastern Euro ...
... to the mantle transition zone. Receiver functions provide valuable information on structural features, which are important for the resolution of European lithospheric dynamics. Moho depths vary from less than 25 km in extensional areas in central Europe to more than 50 km at stations in eastern Euro ...
Origin of marginal basins of the NW Pacific and their plate tectonic
... of dextral pull-apart. The Java, Makassar, Celebes and Sulu Seas basins together with grabens in Borneo also comprise a local dextral, transform-margin type basin system similar to the central and southern parts of the Shanxi Basin in geometry. The overall configuration of the Philippine Sea resemble ...
... of dextral pull-apart. The Java, Makassar, Celebes and Sulu Seas basins together with grabens in Borneo also comprise a local dextral, transform-margin type basin system similar to the central and southern parts of the Shanxi Basin in geometry. The overall configuration of the Philippine Sea resemble ...
Seismic evidence for a chemical heterogeneity in the midmantle: A
... velocity discontinuity (reflector) below the earthquakes. Travel time inversion shows that the seismic reflector dips southwest by 20 at 24.25N, 144.75E, and at a depth of 1115 km with a lateral extension at least 100 100 km. The location corresponds to the lower edge of a high-velocity anomal ...
... velocity discontinuity (reflector) below the earthquakes. Travel time inversion shows that the seismic reflector dips southwest by 20 at 24.25N, 144.75E, and at a depth of 1115 km with a lateral extension at least 100 100 km. The location corresponds to the lower edge of a high-velocity anomal ...
Author`s personal copy - Freie Universität Berlin
... Ever since Steinmann (1905) tried to relate the oceanic affinity of Alpine ophiolites to Alpine folding, a major challenge of Mediterranean geology has been to understand the fate of ocean basins preserved in the circum-Mediterranean mountain belts—how they formed, their size and, finally, how they we ...
... Ever since Steinmann (1905) tried to relate the oceanic affinity of Alpine ophiolites to Alpine folding, a major challenge of Mediterranean geology has been to understand the fate of ocean basins preserved in the circum-Mediterranean mountain belts—how they formed, their size and, finally, how they we ...
Melt generation in the continental crust: answered and unanswered
... temperature for constant-enthalpy assimilation of upper amphibolite-facics rocks into an equal mass of basaltic melt at its liquidus temperature, and also because this is approximately the maximum temperature recorded in mafic granulites which are believed to represent the deep crustal environ- ...
... temperature for constant-enthalpy assimilation of upper amphibolite-facics rocks into an equal mass of basaltic melt at its liquidus temperature, and also because this is approximately the maximum temperature recorded in mafic granulites which are believed to represent the deep crustal environ- ...
The ocean-continent boundary in the Gulf of Lion from analysis of
... has a limited lateral extent seawards. This anomalous crustal structure could be the result of extremely thinned and possibly broken up, continental crust underplated and intruded by partial melt, or could represent serpentinized peridotite material. Important questions about the evolution of the Gu ...
... has a limited lateral extent seawards. This anomalous crustal structure could be the result of extremely thinned and possibly broken up, continental crust underplated and intruded by partial melt, or could represent serpentinized peridotite material. Important questions about the evolution of the Gu ...
A Plate Tectonic Model for the Origin of Porphyry Copper Deposits
... of distincttypesof mineraliz- (Nielsen, 1968; Lowell and Guilbert, 1970). Acation with each stage of geosynclinaldevelopment. cordingto this model, a felsic magma,becoming Porphyrycopperdeposits,for instance,are considered water-saturated as it intrudes towards the surface to typify the post-orogeni ...
... of distincttypesof mineraliz- (Nielsen, 1968; Lowell and Guilbert, 1970). Acation with each stage of geosynclinaldevelopment. cordingto this model, a felsic magma,becoming Porphyrycopperdeposits,for instance,are considered water-saturated as it intrudes towards the surface to typify the post-orogeni ...
Zha, Y., S. C. Webb, S. S. Wei, D. A. Wiens, D. K. Blackman, W
... The current phase of spreading in the Lau basin occurs along several north–south striking segments from 24◦ S to 15◦ S (Conder and Wiens, 2006; Zellmer and Taylor, 2001). From south to north, the spreading rate increases from 30 mm/yr at the southern Valu Fa ridge (VFR) to 95 mm/yr at the northern e ...
... The current phase of spreading in the Lau basin occurs along several north–south striking segments from 24◦ S to 15◦ S (Conder and Wiens, 2006; Zellmer and Taylor, 2001). From south to north, the spreading rate increases from 30 mm/yr at the southern Valu Fa ridge (VFR) to 95 mm/yr at the northern e ...
Final Exam Study Guide File
... 43. Which of the following properties is generally the least useful in identifying minerals? a. hardness c. cleavage b. streak d. color REF: p. 50 OBJ: 2.10 Explain why color is often not a useful property in identifying minerals. MSC: comprehension 44. In areas where unconsolidated sediments are sa ...
... 43. Which of the following properties is generally the least useful in identifying minerals? a. hardness c. cleavage b. streak d. color REF: p. 50 OBJ: 2.10 Explain why color is often not a useful property in identifying minerals. MSC: comprehension 44. In areas where unconsolidated sediments are sa ...
Upper plate proxies for flat-slab subduction processes in southern
... Geochronologic data were not recalibrated using modern standards. Subduction-related magmatism in southern Alaska is attributed to various episodes of volcanic arc activity, as well as subduction of a spreading ridge between ca. 61 and 50 Ma that created a slab-window that allowed for mantle upwelli ...
... Geochronologic data were not recalibrated using modern standards. Subduction-related magmatism in southern Alaska is attributed to various episodes of volcanic arc activity, as well as subduction of a spreading ridge between ca. 61 and 50 Ma that created a slab-window that allowed for mantle upwelli ...
2200 million years of crustal evolution: the baltic shield
... Ma with ISr 0.7024. REE patterns suggest derivation by partial melting of basaltic crustal material. The third generation of granitoids has evolved by remelting of crustal material (Martin and Querré 1984). Greenstone belts A generalized stratigraphic sequence similar to the classical model of Anhae ...
... Ma with ISr 0.7024. REE patterns suggest derivation by partial melting of basaltic crustal material. The third generation of granitoids has evolved by remelting of crustal material (Martin and Querré 1984). Greenstone belts A generalized stratigraphic sequence similar to the classical model of Anhae ...
Ringwood Phase transformations and their bearing on the
... petrological differentia~on of pyrolite at mid-ocean spreading centres to form new oceanic lithosphere. The MORB basaltic crust is underlain by a layer of harzburgite. During subduction, these lithologies each respond to sequential phase transformations in a different manner, so that at any given de ...
... petrological differentia~on of pyrolite at mid-ocean spreading centres to form new oceanic lithosphere. The MORB basaltic crust is underlain by a layer of harzburgite. During subduction, these lithologies each respond to sequential phase transformations in a different manner, so that at any given de ...
cycles in nature biological cycle - National Open University of Nigeria
... present in the atmosphere or found dissolved in surface water. During the process of photosynthesis green plaints, algae and blue green bacteria use energy from the sun to combine with carbon dioxide (c02) from the atmosphere with water (H20) to form carbohydrates. These carbohydrates store energy. ...
... present in the atmosphere or found dissolved in surface water. During the process of photosynthesis green plaints, algae and blue green bacteria use energy from the sun to combine with carbon dioxide (c02) from the atmosphere with water (H20) to form carbohydrates. These carbohydrates store energy. ...
Scandium
... of scandium-bearing oxides have been recognized, and most of these occur in meteorites, such as allendeite [Sc4Zr3O12], named for its type locality, the Allende meteorite. These minerals are rare, and, as described above, most scandium on Earth occurs as a trace component of other minerals. ...
... of scandium-bearing oxides have been recognized, and most of these occur in meteorites, such as allendeite [Sc4Zr3O12], named for its type locality, the Allende meteorite. These minerals are rare, and, as described above, most scandium on Earth occurs as a trace component of other minerals. ...
Evolution of the Eastern Alps
... More eclogitic rocks are present SE and SW of the Tauern Window. The eclogite facies in both cases is surrounded by amphibolite facies rocks. All of those outcrops were dated to the Middle Cretaceous orogeny (110-90 Ma) – an age that is not present in any other metamorphic rock in all of the Alps. A ...
... More eclogitic rocks are present SE and SW of the Tauern Window. The eclogite facies in both cases is surrounded by amphibolite facies rocks. All of those outcrops were dated to the Middle Cretaceous orogeny (110-90 Ma) – an age that is not present in any other metamorphic rock in all of the Alps. A ...
Shear wave anisotropy beneath the Cascadia subduction zone and
... anisotropy may be related to present-day subduction-induced deformation of the mantle beneath the subducting plate. The delay times show an increase with distance from the deformation front (trench), which may be indicative of 3–5 per cent anisotropy within the forearc mantle wedge, with a fast dire ...
... anisotropy may be related to present-day subduction-induced deformation of the mantle beneath the subducting plate. The delay times show an increase with distance from the deformation front (trench), which may be indicative of 3–5 per cent anisotropy within the forearc mantle wedge, with a fast dire ...
Roberts et al., 2013, Basin Modeling
... extracted from these maps and the maps of stretching/thinning factor can be readily converted to maps of top basement heat-flow. The gravity inversion methodology and workflow is summarized in Figure 1a (adapted from Alvey 2010). Key to the success of the gravity inversion method are two geological ...
... extracted from these maps and the maps of stretching/thinning factor can be readily converted to maps of top basement heat-flow. The gravity inversion methodology and workflow is summarized in Figure 1a (adapted from Alvey 2010). Key to the success of the gravity inversion method are two geological ...
Implications of mantle plume structure for the evolution of flood basalts
... escapes from the mantle and loads the earth's surface, followed by slow subsidence over 109 years as the plume's thermal anomaly gradually decays. The timing and duration of volcanism has not been predicted with certainty, but activity is expected to begin as a burst and to die away rapidly over a t ...
... escapes from the mantle and loads the earth's surface, followed by slow subsidence over 109 years as the plume's thermal anomaly gradually decays. The timing and duration of volcanism has not been predicted with certainty, but activity is expected to begin as a burst and to die away rapidly over a t ...
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.