The thermal effects of steady-state slab
... of 75 –90 mW/m2 is observed, with local variations attributed to varying crustal heat production [27,28]. The reduced (deep crust/mantle) heat flow for all regions is 55 –65 mW/m2 [19,27,28], suggesting that there is little variation in the deep thermal structure for the entire Cascadia backarc. One ...
... of 75 –90 mW/m2 is observed, with local variations attributed to varying crustal heat production [27,28]. The reduced (deep crust/mantle) heat flow for all regions is 55 –65 mW/m2 [19,27,28], suggesting that there is little variation in the deep thermal structure for the entire Cascadia backarc. One ...
7 on Contents ∗
... and broadening of the basin took place during Middle and Late Miocene times [e.g. Flecker, 1995; Walsh-Kennedy et al., 2014] (Chapters 3 and 5). Subsidence disruption occurred before Messinian times [e.g. Cosentino et al., 2012; Schildgen et al., 2012b] when a broad surface uplift took place in pres ...
... and broadening of the basin took place during Middle and Late Miocene times [e.g. Flecker, 1995; Walsh-Kennedy et al., 2014] (Chapters 3 and 5). Subsidence disruption occurred before Messinian times [e.g. Cosentino et al., 2012; Schildgen et al., 2012b] when a broad surface uplift took place in pres ...
GEOMORPHOLOGY AND MOUNTAIN BUILDING
... FIG. 8 - The Apennine nappe front. If subduction created the Apen- ...
... FIG. 8 - The Apennine nappe front. If subduction created the Apen- ...
An International Journal of CHAPTER 1 The Island of Elba: tectonic
... imbrication to have started even earlier than described above. Internal stacking of the ophiolitic unit could have happened in the initial deformational stages of the orogenic wedge when compression was being accomodated by thrust faulting of the oceanic crust. Overthrusting of serpentinites on Argi ...
... imbrication to have started even earlier than described above. Internal stacking of the ophiolitic unit could have happened in the initial deformational stages of the orogenic wedge when compression was being accomodated by thrust faulting of the oceanic crust. Overthrusting of serpentinites on Argi ...
THE EARTH`S GRAVITY OUTLINE The Earth`s gravitational field
... (iii) density contrast, e.g. the Southern Uplands Fault and Highland Boundary Fault. ...
... (iii) density contrast, e.g. the Southern Uplands Fault and Highland Boundary Fault. ...
Nitrogen concentration and d N of altered oceanic crust obtained on
... Knowledge of the subduction input flux of nitrogen (N) in altered oceanic crust (AOC) is critical in any attempt to massbalance N across arc-trench systems on a global or individual-margin basis. We have employed sealed-tube, carrier-gas-based methods to examine the N concentrations and isotopic comp ...
... Knowledge of the subduction input flux of nitrogen (N) in altered oceanic crust (AOC) is critical in any attempt to massbalance N across arc-trench systems on a global or individual-margin basis. We have employed sealed-tube, carrier-gas-based methods to examine the N concentrations and isotopic comp ...
Fig. 1
... Despite the importance of continental breakup in plate tectonics, precisely how extensional processes such as brittle faulting, ductile plate stretching, and magma intrusion evolve in space and time during the development of new ocean basins remains poorly understood. The rifting of Arabia from Afri ...
... Despite the importance of continental breakup in plate tectonics, precisely how extensional processes such as brittle faulting, ductile plate stretching, and magma intrusion evolve in space and time during the development of new ocean basins remains poorly understood. The rifting of Arabia from Afri ...
The Eclogite Engine: Chemical geodynamics as
... consistency, material properties that depend on both temperature and pressure, low efficiency, a way to expel waste heat, and obedience to the Second Law distinguish a real engine from a perpetual motion machine. Mantle convection is often simulated with fluids that have constant properties or prope ...
... consistency, material properties that depend on both temperature and pressure, low efficiency, a way to expel waste heat, and obedience to the Second Law distinguish a real engine from a perpetual motion machine. Mantle convection is often simulated with fluids that have constant properties or prope ...
Alkalic magmas generated by partial melting of
... become similar in composition to partial melts of peridotite or hybridized peridotite. Lundstrom et al. (2000) argued that such reactions promote formation of dunite channels. If pyroxenite bodies have relatively large spatial dimensions, their partial melts could segregate into conduits that allow ...
... become similar in composition to partial melts of peridotite or hybridized peridotite. Lundstrom et al. (2000) argued that such reactions promote formation of dunite channels. If pyroxenite bodies have relatively large spatial dimensions, their partial melts could segregate into conduits that allow ...
... elements and geochemically similar elements) form when normal eucrite magmas pass through regions that were heated enough to partially melt. Such partial melts would contain higher levels of elements that are not incorporated readily into major minerals, so have higher concentrations in melted regio ...
Chapter 2 Volcanoes - San Diego State University Department of
... arc lies about 100 ‐ 125 km from the trench. However, if the subducting plate dips steeper, as for example 60o, then the volcanic arc will lie about 58 ‐ 72 km from the trench. In contrast, if the subducting plate dips say 30o, then the volcanic arc will lie about 173 – 217 km from the trench. ...
... arc lies about 100 ‐ 125 km from the trench. However, if the subducting plate dips steeper, as for example 60o, then the volcanic arc will lie about 58 ‐ 72 km from the trench. In contrast, if the subducting plate dips say 30o, then the volcanic arc will lie about 173 – 217 km from the trench. ...
Front, left to right: Mark Handy, Tuncay Taymaz, Jean
... episodic is an important research frontier in the study of active and ancient natural systems, as well as in laboratory and numerical experiments on fault system behavior. Two new developments provide insight into this issue and summon a reevaluation of our concepts of the timescales of fault zone b ...
... episodic is an important research frontier in the study of active and ancient natural systems, as well as in laboratory and numerical experiments on fault system behavior. Two new developments provide insight into this issue and summon a reevaluation of our concepts of the timescales of fault zone b ...
S-Velocity Structure of the Upper Mantle
... ‘spectral-element’ resolution test: inverting published global synthetic data sets computed with the spectral-element method for laterally heterogeneous mantle models, Lebedev and van der Hilst [2008] have been able to reconstruct the synthetic models accurately. The tomographic model displays low-S ...
... ‘spectral-element’ resolution test: inverting published global synthetic data sets computed with the spectral-element method for laterally heterogeneous mantle models, Lebedev and van der Hilst [2008] have been able to reconstruct the synthetic models accurately. The tomographic model displays low-S ...
Zinc isotope evidence for a large-scale carbonated mantle beneath
... shows that the expelled carbon from arc volcanism is much less than that subducted (Kerrick and Connolly, 2001; Johnston et al., 2011). Therefore, a significant mass of non-dissolved carbonates can survive subduction-related dehydration and melting and must be subducted/recycled to the mantle via sla ...
... shows that the expelled carbon from arc volcanism is much less than that subducted (Kerrick and Connolly, 2001; Johnston et al., 2011). Therefore, a significant mass of non-dissolved carbonates can survive subduction-related dehydration and melting and must be subducted/recycled to the mantle via sla ...
Hot spot activity and the break-up of Pangea (PDF
... a model of plate motion during the Pangean break-up. The position of the northern part of Pangea was constrained using Iceland and Jan Mayen hot spots. The Iceland hot spot was traced from its present day position to Greenland in the Paleocene, to Baffin Bay in the Late Cretaceous, to the Alpha Ridg ...
... a model of plate motion during the Pangean break-up. The position of the northern part of Pangea was constrained using Iceland and Jan Mayen hot spots. The Iceland hot spot was traced from its present day position to Greenland in the Paleocene, to Baffin Bay in the Late Cretaceous, to the Alpha Ridg ...
Bresse Graben System, European Crust and Topo Europe
... this day. The rift flanks disinter the same types of rocks as the graben but there are no cretaceous, tertiary or quaternary formations because the rift flanks experienced erosion. Major zones with normal faults define the boundaries between the graben and the rift flanks. The URG consists of a Vari ...
... this day. The rift flanks disinter the same types of rocks as the graben but there are no cretaceous, tertiary or quaternary formations because the rift flanks experienced erosion. Major zones with normal faults define the boundaries between the graben and the rift flanks. The URG consists of a Vari ...
2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... the distribution of trace elements in minerals is strongly controlled by ionic radius and charge. The partition coefficient of a given trace element between solid and melt can be quantitatively described by the elastic strain this element causes by its presence in the crystal lattice. When this stra ...
... the distribution of trace elements in minerals is strongly controlled by ionic radius and charge. The partition coefficient of a given trace element between solid and melt can be quantitatively described by the elastic strain this element causes by its presence in the crystal lattice. When this stra ...
a post-Gravity Recovery and Interior Laboratory reassessment
... revised crustal thicknesses at the Apollo 12, 14, 15 and 16 sites of 33 ± 5, 31 ± 7, 35 ± 8 and 38 ± 7 km, respectively. In an inversion by Hikida & Wieczorek [28], they required only that the minimum crustal thickness be less than 1 km and obtained an average crustal thickness of 43 km, with a thic ...
... revised crustal thicknesses at the Apollo 12, 14, 15 and 16 sites of 33 ± 5, 31 ± 7, 35 ± 8 and 38 ± 7 km, respectively. In an inversion by Hikida & Wieczorek [28], they required only that the minimum crustal thickness be less than 1 km and obtained an average crustal thickness of 43 km, with a thic ...
Chapter 16. Noble Gas Isotopes
... Both high-R and low-R domains may coexist in the upper mantle , as long as they are larger than diffusion distances; these can be commingled during the melting process or sampled separately if sampling is done at a small scale. The so-called high-He hotspots exhibit very large variance (Figure 16.2) ...
... Both high-R and low-R domains may coexist in the upper mantle , as long as they are larger than diffusion distances; these can be commingled during the melting process or sampled separately if sampling is done at a small scale. The so-called high-He hotspots exhibit very large variance (Figure 16.2) ...
Structure of the crust and uppermost mantle of Iceland from
... single large-scale smeared dome modelled here (see Section 2.2.1). In this case the gravity minimum may coincide with a thicker section of upper crust between the domes. The track of the ICEMELT pro¢le passes between the three central volcanoes beneath northwest Vatnajo«kull. It is also possible tha ...
... single large-scale smeared dome modelled here (see Section 2.2.1). In this case the gravity minimum may coincide with a thicker section of upper crust between the domes. The track of the ICEMELT pro¢le passes between the three central volcanoes beneath northwest Vatnajo«kull. It is also possible tha ...
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.