The structure and dynamics of the mantle wedge
... of deformation that takes place is strongly dependent on temperature, pressure, applied stress and composition. At the low temperatures near the Earth’s surface most silicate rock deforms in a brittle fashion leading to faulting and earthquakes. At higher temperatures viscous deformation takes over, ...
... of deformation that takes place is strongly dependent on temperature, pressure, applied stress and composition. At the low temperatures near the Earth’s surface most silicate rock deforms in a brittle fashion leading to faulting and earthquakes. At higher temperatures viscous deformation takes over, ...
EAST AFRICAN RIFT SYSTEM
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
EAST AFRICAN RIFT SYSTEM
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
Pb composition of Mesozoic Pacific oceanic crust
... Pb/204Pb and 208Pb/204Pb ratios. Three samples from Site 801 display the most extreme 206Pb/204Pb (23.70–26.86) and 207Pb/204Pb (15.73–15.83) ratios ever measured in altered MORB reflecting an increase of 238U/204Pb ratios (m), most likely through addition of seawater derived U. Initial Pb isotopes ...
... Pb/204Pb and 208Pb/204Pb ratios. Three samples from Site 801 display the most extreme 206Pb/204Pb (23.70–26.86) and 207Pb/204Pb (15.73–15.83) ratios ever measured in altered MORB reflecting an increase of 238U/204Pb ratios (m), most likely through addition of seawater derived U. Initial Pb isotopes ...
evidence from Th, Sr and Pb isotope data for Tonga
... However, samples from Tafahi and Niuatoputapu islands have very different Pb isotope compositions to lavas from other arcs in the western Pacific, in ...
... However, samples from Tafahi and Niuatoputapu islands have very different Pb isotope compositions to lavas from other arcs in the western Pacific, in ...
Rheological Response to Tectonic and Volcanic
... Iceland is one of the few places in the world where a Mid-Oceanic Ridge (MOR) is exposed on land, and this gives good opportunity to study geodynamic processes. Spreading of MidAtlantic Ocean Ridge (MAR) segments in Iceland began ~60 million years ago. The MAR segments in Iceland have a divergent sp ...
... Iceland is one of the few places in the world where a Mid-Oceanic Ridge (MOR) is exposed on land, and this gives good opportunity to study geodynamic processes. Spreading of MidAtlantic Ocean Ridge (MAR) segments in Iceland began ~60 million years ago. The MAR segments in Iceland have a divergent sp ...
church_hall
... 1987, p. 44; Thibault 1987, p. 28). Thy (1987), however, claims that the less fractionated part of the stratiform unit is younger than the more fractionated part—which it nevertheless underlies. In this respect the plutonic series likely correlates with either the older low-Ti series of the BG and L ...
... 1987, p. 44; Thibault 1987, p. 28). Thy (1987), however, claims that the less fractionated part of the stratiform unit is younger than the more fractionated part—which it nevertheless underlies. In this respect the plutonic series likely correlates with either the older low-Ti series of the BG and L ...
hall_church_comments
... within the Arakapas fault zone are usually taken to have formed in an oceanic transform fault (Murton and Gass 1986) While it is not possible to differentiate in terms of Ti between the low-Ti rocks of the BG-LPL and the UPL units, Desmet (1977, p. 54) stated that the UPL lavas differ from those of ...
... within the Arakapas fault zone are usually taken to have formed in an oceanic transform fault (Murton and Gass 1986) While it is not possible to differentiate in terms of Ti between the low-Ti rocks of the BG-LPL and the UPL units, Desmet (1977, p. 54) stated that the UPL lavas differ from those of ...
ferrari answers
... related to the dehydration of the slab so a period of high convergence rate may have produced an increase in fluids released from the subducting plate. Another possibility is that North America actively overrode the Cocos plate in the early Miocene (i.e. Cocos do not retreat at the same velocity of ...
... related to the dehydration of the slab so a period of high convergence rate may have produced an increase in fluids released from the subducting plate. Another possibility is that North America actively overrode the Cocos plate in the early Miocene (i.e. Cocos do not retreat at the same velocity of ...
Mantle Influence, Rifting and Magmatism in the East African Rift
... mechanically weak, newly formed crust. On the other hand, the Kenya rift developed in terrain occupied by the Mozambique Belt (MB), the southern member of the EAO. The MB is made up of reactivated pre-existing terrains having mechanical characteristics which were partially modified by the Panafrican ...
... mechanically weak, newly formed crust. On the other hand, the Kenya rift developed in terrain occupied by the Mozambique Belt (MB), the southern member of the EAO. The MB is made up of reactivated pre-existing terrains having mechanical characteristics which were partially modified by the Panafrican ...
Hilliker 1 The Effects of the Farallon Plate Subduction Frank Hilliker
... planet’s lithosphere have drifted across the inner aesthenosphere. These sections (plates) form at a three-pronged junction with the ensuing cracks running until they intersect another threepronged point. At these cracks the now-divided plates function in one of three ways: they diverge, converge, o ...
... planet’s lithosphere have drifted across the inner aesthenosphere. These sections (plates) form at a three-pronged junction with the ensuing cracks running until they intersect another threepronged point. At these cracks the now-divided plates function in one of three ways: they diverge, converge, o ...
Role of the subducted slab, mantle wedge and
... meters above sea level, and summit elevations of these volcanoes and other peaks of the southernmost Andes are generally less than 3,000 m. This suggests crustal thickness of ,35 km, similar to below the southern Andes everywhere south of 368S (Ramos and Kay l992; Kay et al. l993). Xenoliths of lowe ...
... meters above sea level, and summit elevations of these volcanoes and other peaks of the southernmost Andes are generally less than 3,000 m. This suggests crustal thickness of ,35 km, similar to below the southern Andes everywhere south of 368S (Ramos and Kay l992; Kay et al. l993). Xenoliths of lowe ...
Convergence and Collision
... F I G U R E 1 7 . 1 (a) Photo of the southern Andes Mountains of Chile. Rocks exposed on these peaks include relicts of old accretionary prisms, as well as granitic intrusions of a continental volcanic arc. (b) Photo of the central Himalaya Mountains, Nepal. The highest peak, which appears to be nuc ...
... F I G U R E 1 7 . 1 (a) Photo of the southern Andes Mountains of Chile. Rocks exposed on these peaks include relicts of old accretionary prisms, as well as granitic intrusions of a continental volcanic arc. (b) Photo of the central Himalaya Mountains, Nepal. The highest peak, which appears to be nuc ...
EAST AFRICAN RIFT SYSTEM
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
... stress builds up for a long period of time (centuries) to breaking limit. Overstretched zone of weakness opens up along pre-existing faults and basalt intrudes into them at depth (dyking). Fissure eruptions may occur depending of magma supply. The caldera (central) volcanoes of the rift are underlai ...
Genesis of the Neogene to Quaternary volcanism in the Carpathian
... Neogene to Quaternary volcanism of the Carpathian-Pannonian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. Using the spatial and temporal distribution of the magmatic rocks, their major- and traceelement features, and Sr-Nd-Pb isotope characteristics, ...
... Neogene to Quaternary volcanism of the Carpathian-Pannonian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. Using the spatial and temporal distribution of the magmatic rocks, their major- and traceelement features, and Sr-Nd-Pb isotope characteristics, ...
Origin and evolution of the lower crust in magmatic
... Thin oceanic crust is formed by decompression melting of the upper mantle at mid-ocean ridges, but the origin of the thick and buoyant continental crust is enigmatic. Juvenile continental crust may form from magmas erupted above intraoceanic subduction zones, where oceanic lithosphere subducts benea ...
... Thin oceanic crust is formed by decompression melting of the upper mantle at mid-ocean ridges, but the origin of the thick and buoyant continental crust is enigmatic. Juvenile continental crust may form from magmas erupted above intraoceanic subduction zones, where oceanic lithosphere subducts benea ...
Diapirs as the source of the sediment signature in arc lavas
... melt’ signature in arc lavas2–4 . Subduction zone thermal models that incorporate temperature- and stress-dependent viscosity5–8 produce slab-top temperatures above the fluid-saturated sediment solidus (>600–700 ◦ C at ≤3 GPa; refs 9,10), and H2 O/Ce and H2 O/K ratios in melt inclusions from arc lav ...
... melt’ signature in arc lavas2–4 . Subduction zone thermal models that incorporate temperature- and stress-dependent viscosity5–8 produce slab-top temperatures above the fluid-saturated sediment solidus (>600–700 ◦ C at ≤3 GPa; refs 9,10), and H2 O/Ce and H2 O/K ratios in melt inclusions from arc lav ...
Thermal modelling of the Laramide orogeny: testing the £at
... If stress coupling of the upper and lower plates was the driving mechanism for inboard deformation during the Laramide orogeny, the e¡ect of shear heating along this interface must be considered. Shear heating along the subduction interface provides an additional source of heat and results in warmin ...
... If stress coupling of the upper and lower plates was the driving mechanism for inboard deformation during the Laramide orogeny, the e¡ect of shear heating along this interface must be considered. Shear heating along the subduction interface provides an additional source of heat and results in warmin ...
The Yellowstone magmatic system from the
... explaining the magnitude of CO 2 discharge, and constraining dynamic at depths of 5 to 10 km, which is models of the magmatic system for volcanic hazard assessment. often interpreted as a magma reservoir. Several of these studies also image the top of a second The interaction of the North American P ...
... explaining the magnitude of CO 2 discharge, and constraining dynamic at depths of 5 to 10 km, which is models of the magmatic system for volcanic hazard assessment. often interpreted as a magma reservoir. Several of these studies also image the top of a second The interaction of the North American P ...
Thermal Structure and Metamorphic Evolution of Subducting Slabs
... convection and the negative buoyancy of slabs (slab pull) drives plate tectonics [Forsyth and Uyeda, 1975]. Subduction zones are regions of intense earthquake activity, explosive volcanism, and complex mass transfer between the crust, mantle, hydrosphere, and atmosphere. In this contribution, I focu ...
... convection and the negative buoyancy of slabs (slab pull) drives plate tectonics [Forsyth and Uyeda, 1975]. Subduction zones are regions of intense earthquake activity, explosive volcanism, and complex mass transfer between the crust, mantle, hydrosphere, and atmosphere. In this contribution, I focu ...
Cinder cones of Mount Slamet, Central Java, Indonesia
... large collapse structure towards north followed by multiphase eruptions to build up the young cone, as Mount Slamet. There is a possibility that the collapse was accompanied by a formation of the cinder cones. The collapse probably ...
... large collapse structure towards north followed by multiphase eruptions to build up the young cone, as Mount Slamet. There is a possibility that the collapse was accompanied by a formation of the cinder cones. The collapse probably ...
1 The role of the mantle wedge in subduction zone dynamics and
... of sediments derived from biogenic activity in the oceans and from continental erosion add to the chemical diversity. While the mid-oceanic ridges are generally considered passive features, caused by the pull-apart of the surrounding oceanic lithosphere, subduction zones form the main driving force ...
... of sediments derived from biogenic activity in the oceans and from continental erosion add to the chemical diversity. While the mid-oceanic ridges are generally considered passive features, caused by the pull-apart of the surrounding oceanic lithosphere, subduction zones form the main driving force ...
Heterogeneous sources for Pleistocene lavas of Marie Byrd Land
... bedrock surfaces at low elevations. Many volcanic exposures consist of delicate tephra, cinder, and splatter forms, not evidently modified by wet-based glacial ice. In addition, a few necks and irregular conduits cut through bedrock near a north-south-striking vertical fault in the Ochs Glacier area ...
... bedrock surfaces at low elevations. Many volcanic exposures consist of delicate tephra, cinder, and splatter forms, not evidently modified by wet-based glacial ice. In addition, a few necks and irregular conduits cut through bedrock near a north-south-striking vertical fault in the Ochs Glacier area ...
Crustal structure and evolution of the Mariana intra
... fied products (the arc crust) are derived from primary basaltic magmas generated in the mantle wedge. At the juvenile stage of arc evolution, the mantle-derived basalt magma forms the initial arc crust, which is most simply composed of differentiated basalt and cumulate layers. This model regards th ...
... fied products (the arc crust) are derived from primary basaltic magmas generated in the mantle wedge. At the juvenile stage of arc evolution, the mantle-derived basalt magma forms the initial arc crust, which is most simply composed of differentiated basalt and cumulate layers. This model regards th ...
Physical Processes Along Internal Boundaries In An Con
... for complex evaluation of composite magmatic systems. In the present study, we focus on physical processes operating along internal boundaries between individual magma pulses in a magmatic system, evolving from early sheeting to younger nested diapirs (Tuolumne Batholith, central Sierra Nevada, USA) ...
... for complex evaluation of composite magmatic systems. In the present study, we focus on physical processes operating along internal boundaries between individual magma pulses in a magmatic system, evolving from early sheeting to younger nested diapirs (Tuolumne Batholith, central Sierra Nevada, USA) ...
Cascade Volcanoes
This article is for the volcanic arc. For the namesake mountain range see Cascade Range.The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles (1,100 km). The arc has formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.Some of the major cities along the length of the arc include Portland, Seattle, and Vancouver, and the population in the region exceeds 10,000,000. All could be potentially affected by volcanic activity and great subduction-zone earthquakes along the arc. Because the population of the Pacific Northwest is rapidly increasing, the Cascade volcanoes are some of the most dangerous, due to their eruptive history and potential for future eruptions, and because they are underlain by weak, hydrothermally altered volcanic rocks that are susceptible to failure. Consequently, Mount Rainier is one of the Decade Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being worthy of particular study, due to the danger it poses to Seattle and Tacoma. Many large, long-runout landslides originating on Cascade volcanoes have inundated valleys tens of kilometers from their sources, and some of the inundated areas now support large populations.The Cascade Volcanoes are part of the Pacific Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. All of the known historic eruptions in the contiguous United States have been from the Cascade Volcanoes. Two most recent were Lassen Peak in 1914 to 1921 and a major eruption of Mount St. Helens in 1980. It is also the site of Canada's most recent major eruption about 2,350 years ago at the Mount Meager volcanic complex.