Rheology and strength of the lithosphere - Evgueni Burov
... (plastic) or viscous (ductile) properties. As can be inferred from rock mechanics data, a large part of the long-term lithospheric strength is supported in the ductile or ductileeelastic regime, while it also maintains important brittle strength. Yet, at short seismic time scale (s), the entire lith ...
... (plastic) or viscous (ductile) properties. As can be inferred from rock mechanics data, a large part of the long-term lithospheric strength is supported in the ductile or ductileeelastic regime, while it also maintains important brittle strength. Yet, at short seismic time scale (s), the entire lith ...
Thinning of continental backarc lithosphere by flow
... the volcanic arc region, as most water is driven from the subducting plate at shallow depths. It is difficult to explain observations of thin lithosphere hundreds of kilometers behind the arc with this mechanism, unless slab-derived water can be carried far into the backarc, perhaps by transport in t ...
... the volcanic arc region, as most water is driven from the subducting plate at shallow depths. It is difficult to explain observations of thin lithosphere hundreds of kilometers behind the arc with this mechanism, unless slab-derived water can be carried far into the backarc, perhaps by transport in t ...
Mobility and immobility of mid-ocean ridges and their implications to
... complexity in the equatorial Atlantic region, an area characterised by a dense pattern of mostly medium to large offset fracture zones as well as a series of unusual ridges and troughs (Mueller and Smith, 1993). These investigators have also suggested that the equatorial Atlantic region recorded th ...
... complexity in the equatorial Atlantic region, an area characterised by a dense pattern of mostly medium to large offset fracture zones as well as a series of unusual ridges and troughs (Mueller and Smith, 1993). These investigators have also suggested that the equatorial Atlantic region recorded th ...
Metamorphic reworking of a high - Lamont
... immediately after HP metamorphism whereas the northern association was retrograded during a later collision that thrust it northward at ca. 70 Ma. They were subsequently juxtaposed opposite each other by major strike slip motion. This model implies that the HP rocks on opposing sides of the Motagua ...
... immediately after HP metamorphism whereas the northern association was retrograded during a later collision that thrust it northward at ca. 70 Ma. They were subsequently juxtaposed opposite each other by major strike slip motion. This model implies that the HP rocks on opposing sides of the Motagua ...
the Scotia Sea and the Caribbean
... Holmes’ (1898-1965) ideas regarding mantle convection, and Harry Hess’ (1906-1969) seafloor spreading hypothesis, the theory of plate tectonics has been accepted since the 1960s. According to this theory, the Earth is subdivided into several rigid plates that move with a few centimeters per year rel ...
... Holmes’ (1898-1965) ideas regarding mantle convection, and Harry Hess’ (1906-1969) seafloor spreading hypothesis, the theory of plate tectonics has been accepted since the 1960s. According to this theory, the Earth is subdivided into several rigid plates that move with a few centimeters per year rel ...
Toward the reconciliation of seismological and petrological
... analysis of xenolith samples from the Solomon Islands sampling material from the Ontong Jave plateau. The material down to 85 km is thought to be related to the former Pacific plate rather than the subsequent modification by plume influence. This upper zone shows variations in Vp and Vs from the lherzo ...
... analysis of xenolith samples from the Solomon Islands sampling material from the Ontong Jave plateau. The material down to 85 km is thought to be related to the former Pacific plate rather than the subsequent modification by plume influence. This upper zone shows variations in Vp and Vs from the lherzo ...
Hotspot Geodynamics Detailed Planning Group
... and the newer model reflects "deeper" flow because of more massive plumes. Hence, the newer results agree less well with observations. Kerguelen is really the only hotspot for which the latest modeling results are substantially different from older ones. Ocean floor age changes across the Ninetyeast ...
... and the newer model reflects "deeper" flow because of more massive plumes. Hence, the newer results agree less well with observations. Kerguelen is really the only hotspot for which the latest modeling results are substantially different from older ones. Ocean floor age changes across the Ninetyeast ...
poster technical sessions
... hazards and mineral-energy resource potential, which brings more societal relevance to this international scientific gathering. Situated at the intersection of the Eurasian, African, and Arabian plates, Anatolia and the eastern Mediterranean region form one of the most seismically and volcanically a ...
... hazards and mineral-energy resource potential, which brings more societal relevance to this international scientific gathering. Situated at the intersection of the Eurasian, African, and Arabian plates, Anatolia and the eastern Mediterranean region form one of the most seismically and volcanically a ...
Tectonic controls on the nature of large silicic calderas in volcanic arcs
... on the nearest transect(s) reported in Lallemand et al. (2005) (Fig. 1B). Extension was examined at two scales. First, in order to characterize the overall stress regime of the arc, we utilized the backarc classifications for transects, also from Lallemand et al. (2005). These values are based on up ...
... on the nearest transect(s) reported in Lallemand et al. (2005) (Fig. 1B). Extension was examined at two scales. First, in order to characterize the overall stress regime of the arc, we utilized the backarc classifications for transects, also from Lallemand et al. (2005). These values are based on up ...
Continental Growth and Recycling in Convergent Orogens with
... at the time of accretion. This crust only produces significant zircon when and if it partially melts, which may occur long after accretion. Keywords: continental growth; tectonics; turbidites; subduction; Gondwana; Damara Orogen; Lachlan Orogen; New Zealand ...
... at the time of accretion. This crust only produces significant zircon when and if it partially melts, which may occur long after accretion. Keywords: continental growth; tectonics; turbidites; subduction; Gondwana; Damara Orogen; Lachlan Orogen; New Zealand ...
Antigorite Peridotite, Metaserpentinite, and other
... igneous rock, makes up most of the field; however, the peridotite samples studied here are hosted in diatremes of serpentinized ultramafic microbreccia (SUM). Crystal fragments of pyrope, olivine, and pyroxene in the microbreccia occur in a serpentine-rich matrix. The SUM was emplaced as crystals an ...
... igneous rock, makes up most of the field; however, the peridotite samples studied here are hosted in diatremes of serpentinized ultramafic microbreccia (SUM). Crystal fragments of pyrope, olivine, and pyroxene in the microbreccia occur in a serpentine-rich matrix. The SUM was emplaced as crystals an ...
PDF
... It is important to stress that the SIR established herein is based upon selected Tethyan ophiolites in which chemostratigraphic relations are sufficiently clear, thanks to many detailed studies over the past three decades. We do not think this geographic focus jeopardizes the significance of our con ...
... It is important to stress that the SIR established herein is based upon selected Tethyan ophiolites in which chemostratigraphic relations are sufficiently clear, thanks to many detailed studies over the past three decades. We do not think this geographic focus jeopardizes the significance of our con ...
Primary magmas and mantle temperatures
... Abstract: The composition of olivine phenocrysts in Hawaiian tholeiitic picrites and in Mid-Ocean Ridge picrites vary up to Mg#91.3 and Mg#92.1 respectively. The compositions and liquidus temperatures of the magmas crystallizing the most magnesian phenocrysts can be estimated and we find that anhydr ...
... Abstract: The composition of olivine phenocrysts in Hawaiian tholeiitic picrites and in Mid-Ocean Ridge picrites vary up to Mg#91.3 and Mg#92.1 respectively. The compositions and liquidus temperatures of the magmas crystallizing the most magnesian phenocrysts can be estimated and we find that anhydr ...
Continental rifting as a function of lithosphere mantle strength
... forces — i.e. softening the lithosphere during extension by the thinning of brittle layers and general heating. Narrow rifts occur when the total force change on rifting is negative, so that the ongoing thinning is kept in the same narrow region. On the contrary, wide rifts occur when the total forc ...
... forces — i.e. softening the lithosphere during extension by the thinning of brittle layers and general heating. Narrow rifts occur when the total force change on rifting is negative, so that the ongoing thinning is kept in the same narrow region. On the contrary, wide rifts occur when the total forc ...
Rhenium–osmium isotope and elemental behaviour during
... thought to reflect the processes of differentiation and recycling that have occurred throughout geological history, and this chemical heterogeneity of the mantle is sampled at the present-day by basaltic volcanism. Mid-ocean ridge basalts (MORB) sample mantle material that is depleted in incompatibl ...
... thought to reflect the processes of differentiation and recycling that have occurred throughout geological history, and this chemical heterogeneity of the mantle is sampled at the present-day by basaltic volcanism. Mid-ocean ridge basalts (MORB) sample mantle material that is depleted in incompatibl ...
sample test
... ____ 35. Oceanic crust near the mid-ocean ridge is younger than oceanic crust farther away from the ridge. _________________________ ____ 36. If subduction occurs faster than oceanic crust can be created, an ocean will expand. _________________________ ____ 37. Along a divergent boundary, two plates ...
... ____ 35. Oceanic crust near the mid-ocean ridge is younger than oceanic crust farther away from the ridge. _________________________ ____ 36. If subduction occurs faster than oceanic crust can be created, an ocean will expand. _________________________ ____ 37. Along a divergent boundary, two plates ...
On the origin of noble gases in mantle plumes
... but signi cant volume of material (from 10 to 35%) has not seen the surface (van Keken & Ballentine 1998; Ferrachat & Ricard 2001; Coltice et al . 2000b). Keeping any sort of chemical layering implies the existence of a stabilizing density strati cation, and preserving an undegassed abyssal layer ...
... but signi cant volume of material (from 10 to 35%) has not seen the surface (van Keken & Ballentine 1998; Ferrachat & Ricard 2001; Coltice et al . 2000b). Keeping any sort of chemical layering implies the existence of a stabilizing density strati cation, and preserving an undegassed abyssal layer ...
Alps vs. Apennines - Dipartimento di Scienze della Terra
... This article will summarize the main achievements in understanding the post-Paleozoic Italian geology, showing how the differences between Alps and Apennines (Laubscher, 1988; Royden and Burchfiel, 1989; Doglioni, 1992) mark an asymmetry. This is similar to what can be followed in subduction zones wo ...
... This article will summarize the main achievements in understanding the post-Paleozoic Italian geology, showing how the differences between Alps and Apennines (Laubscher, 1988; Royden and Burchfiel, 1989; Doglioni, 1992) mark an asymmetry. This is similar to what can be followed in subduction zones wo ...
TROPICS Continent-Building in Costa Rica
... crust of oceanic origin that is undergoing both subduction and underthrusting and that is also developing features characteristic of continents, including the emplacement of arc magmas that are unusually similar in composition to continental crust. The simultaneous presences of these three attribute ...
... crust of oceanic origin that is undergoing both subduction and underthrusting and that is also developing features characteristic of continents, including the emplacement of arc magmas that are unusually similar in composition to continental crust. The simultaneous presences of these three attribute ...
Plumes and Hotspots
... of a mantle plume depends on the depth of emplacement of the hot plume head at the base of the lithosphere, and the presence of recycled oceanic crusts in the form of eclogite in the plume source. Modelling indicates a melting rate of 1–10 km3/a, and a total melt volume of 1–20 million km3, dependin ...
... of a mantle plume depends on the depth of emplacement of the hot plume head at the base of the lithosphere, and the presence of recycled oceanic crusts in the form of eclogite in the plume source. Modelling indicates a melting rate of 1–10 km3/a, and a total melt volume of 1–20 million km3, dependin ...
The Architecture, Chemistry, and Evolution of Continental Magmatic
... subduction magmatism where the upper plate is continental and/or accreted transitional lithosphere. The active-type example is the Andean arc of South America. Well-studied deeply exhumed analogs to the Andean volcanic arc occur as composite batholiths along western North America. The South and Nort ...
... subduction magmatism where the upper plate is continental and/or accreted transitional lithosphere. The active-type example is the Andean arc of South America. Well-studied deeply exhumed analogs to the Andean volcanic arc occur as composite batholiths along western North America. The South and Nort ...
Campbell, I.H., Large Igneous Provinces and the mantle plume
... The plate tectonic hypothesis provides an elegant explanation for Earth’s two principal types of basaltic volcanism, mid-ocean ridge and island arc volcanism, both of which occur at plate boundaries. Mid-ocean ridge basalts form new ocean crust along the tensional zones that develop where adjacent p ...
... The plate tectonic hypothesis provides an elegant explanation for Earth’s two principal types of basaltic volcanism, mid-ocean ridge and island arc volcanism, both of which occur at plate boundaries. Mid-ocean ridge basalts form new ocean crust along the tensional zones that develop where adjacent p ...
nature ano evolution of the subcontinental mantle lithosphere below
... Ultramafic xenoliths found in the Pleistocene Pali-Aike alkali basalts, the southernmost outcropping of the Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicat ...
... Ultramafic xenoliths found in the Pleistocene Pali-Aike alkali basalts, the southernmost outcropping of the Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicat ...
Crust and upper mantle discontinuity structure beneath eastern
... refraction profiles and because individual refraction profiles manifest considerable variation even within given tectonic terranes, we did not assume different crustal velocities for different segments of the array. Rather, we modeled all observed crustal receiver functions with three Vp and Vp /Vs ...
... refraction profiles and because individual refraction profiles manifest considerable variation even within given tectonic terranes, we did not assume different crustal velocities for different segments of the array. Rather, we modeled all observed crustal receiver functions with three Vp and Vp /Vs ...
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few mm to over ten cm per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr.