- Arizona State University
... al., 1987]. After perhaps 10 Myr of relative quiescence, rift activity resumed with high-angle normal faulting and alkalic basaltic volcanism [e.g., Baldridge et al., 1991]. During the past 4 Myr there has been increased volcanism along the Jemez Lineament (Figure 1), including the Mount Taylor regi ...
... al., 1987]. After perhaps 10 Myr of relative quiescence, rift activity resumed with high-angle normal faulting and alkalic basaltic volcanism [e.g., Baldridge et al., 1991]. During the past 4 Myr there has been increased volcanism along the Jemez Lineament (Figure 1), including the Mount Taylor regi ...
Aleutian white paper 1
... Aleutian lower crust appear to be higher than for IBM, but interpretation of these data is complicated by the unusual nature of the two arc crossings, and the oblique fore-arc to arc geometry of the one strike line. In any case, our focus here is on the plutonic middle crust. Systematic study of coe ...
... Aleutian lower crust appear to be higher than for IBM, but interpretation of these data is complicated by the unusual nature of the two arc crossings, and the oblique fore-arc to arc geometry of the one strike line. In any case, our focus here is on the plutonic middle crust. Systematic study of coe ...
Plumes and Hotspots
... of density differences due to temperature between materials on either side of the layer. The earth interior has two such thermal boundary layers—the crust-mantle boundary, where heat is transferred by conduction, and the lower mantle-outer core boundary, where heat conduction takes place by convecti ...
... of density differences due to temperature between materials on either side of the layer. The earth interior has two such thermal boundary layers—the crust-mantle boundary, where heat is transferred by conduction, and the lower mantle-outer core boundary, where heat conduction takes place by convecti ...
Chapter 14. Magmas: Windows into the Mantle
... model involves transport of cold slabs, including the crust, to the core-mantle boundary (CMB) where they heat up and generate ~ 3000 km deep narrow plumes that come up under oceanic islands . Enrichment of the lower part of the lithosphere by upward migrating metasomatic melts and fluids, and ineff ...
... model involves transport of cold slabs, including the crust, to the core-mantle boundary (CMB) where they heat up and generate ~ 3000 km deep narrow plumes that come up under oceanic islands . Enrichment of the lower part of the lithosphere by upward migrating metasomatic melts and fluids, and ineff ...
Mantle temperature control on composition of arc magmas along the
... Abundant volcanism in the Central Kamchatka Depression (CKD) adjacent to the Kamchatka–Aleutian Arc junction occurs where the Pacific slab edge is subducting beneath Kamchatka. Here we summarize published data on CKD rocks and demonstrate a systematic south-to-north change of their compositions from ...
... Abundant volcanism in the Central Kamchatka Depression (CKD) adjacent to the Kamchatka–Aleutian Arc junction occurs where the Pacific slab edge is subducting beneath Kamchatka. Here we summarize published data on CKD rocks and demonstrate a systematic south-to-north change of their compositions from ...
Reference crust-mantle density contrast beneath Antarctica based
... Moho density contrast differs significantly in East and West Antarctica (see Fig. 3). Moho density contrast maxima are situated throughout the central part of East Antarctica with the extension under the Transantarctic mountain range. Moho density contrast there exceeded 500 kg/m3. Moho density cont ...
... Moho density contrast differs significantly in East and West Antarctica (see Fig. 3). Moho density contrast maxima are situated throughout the central part of East Antarctica with the extension under the Transantarctic mountain range. Moho density contrast there exceeded 500 kg/m3. Moho density cont ...
PHYSICAL GEOLOGY LECTURE NOTES, PAGE I. Introduction
... 100 to 350 kms) and the Mesosphere (relatively solid, rigid material that extends from 350 to 2900 kms) c. Core - composed mostly of an iron-nickel alloy ...
... 100 to 350 kms) and the Mesosphere (relatively solid, rigid material that extends from 350 to 2900 kms) c. Core - composed mostly of an iron-nickel alloy ...
A Lithospheric CrossSection Through the Swiss AlpsI
... about 92 Ma this period was followed by the main compressional episodes of the Alpine orogeny, due to rifting in the central Atlantic: the Cretaceous Eoalpine phase, and the Tertiary Meso- and Neoalpine phases (e.g. Triimpy 1973, 1982). The geometry of the tectonic structure is well constrained (Fig ...
... about 92 Ma this period was followed by the main compressional episodes of the Alpine orogeny, due to rifting in the central Atlantic: the Cretaceous Eoalpine phase, and the Tertiary Meso- and Neoalpine phases (e.g. Triimpy 1973, 1982). The geometry of the tectonic structure is well constrained (Fig ...
Campbell, I.H., Large Igneous Provinces and the mantle plume
... An obvious weakness of the thermal plume hypothesis is that it fails to explain a number of minor volcanic chains that stretch across the ocean basin and cannot be linked to LIPs. These appear to be the product of plume tails without heads. It has been suggested that the plumes responsible for these ...
... An obvious weakness of the thermal plume hypothesis is that it fails to explain a number of minor volcanic chains that stretch across the ocean basin and cannot be linked to LIPs. These appear to be the product of plume tails without heads. It has been suggested that the plumes responsible for these ...
North America Dynamics and Western US Tectonics
... view of the forces responsible for plate motion has edge forces driving rigid plates over a weak and relatively static asthenosphere that acts to resist plate motion. Recently, this view has been challenged by some global geodynamicists, who advocate a model with mantle flow (driven primarily by oce ...
... view of the forces responsible for plate motion has edge forces driving rigid plates over a weak and relatively static asthenosphere that acts to resist plate motion. Recently, this view has been challenged by some global geodynamicists, who advocate a model with mantle flow (driven primarily by oce ...
PPT - Margins
... of mantle melt (Lizzaradle et al., 2007): earlier transition to narrow rift mode • Reduction of differences in buoyancy forces (Bialas and Buck, 2007; submitted): earlier transition to narrow rift mode • Diffuse deformation, after transition to narrow rift mode (Persaud et al., 2003) • Build new tra ...
... of mantle melt (Lizzaradle et al., 2007): earlier transition to narrow rift mode • Reduction of differences in buoyancy forces (Bialas and Buck, 2007; submitted): earlier transition to narrow rift mode • Diffuse deformation, after transition to narrow rift mode (Persaud et al., 2003) • Build new tra ...
Chapter 7. Radiogenic Isotope Geochemistry of the Crust and Oceans
... As we found in Chapter 5, 182Hf (half-life 9 Ma) was present in the early Solar System and the silicate Earth’s 182W/184W is about 2 epsilon units higher than chondrites. The difference reflects sequestration of W in the Earth’s core (or, more likely, the cores of the planetary embryos that accreted ...
... As we found in Chapter 5, 182Hf (half-life 9 Ma) was present in the early Solar System and the silicate Earth’s 182W/184W is about 2 epsilon units higher than chondrites. The difference reflects sequestration of W in the Earth’s core (or, more likely, the cores of the planetary embryos that accreted ...
Local earthquake tomography of central Costa Rica
... along the plate boundary. Offshore, close to the shoreline, the plate boundary is generally found at 12–15 km depth. The dip of the plate boundary is decreasing from northwest (NW) to southeast (SE), and the margin wedge is thinnest in central Costa Rica where numerous seamounts are subducted. This ...
... along the plate boundary. Offshore, close to the shoreline, the plate boundary is generally found at 12–15 km depth. The dip of the plate boundary is decreasing from northwest (NW) to southeast (SE), and the margin wedge is thinnest in central Costa Rica where numerous seamounts are subducted. This ...
Crustal Growth by Magmatic Accretion
... included within clinopyroxene rims adjacent to plagioclase. These quartz textures seem to be formed by breakdown reactions of plagioclase: anorthite ¼ Ca Tschermaks (in clinopyroxene) þ quartz and albite ¼ jadeite (in clinopyroxene) þ quartz. Yoshino et al. (1998) classified zoning patterns of Al in ...
... included within clinopyroxene rims adjacent to plagioclase. These quartz textures seem to be formed by breakdown reactions of plagioclase: anorthite ¼ Ca Tschermaks (in clinopyroxene) þ quartz and albite ¼ jadeite (in clinopyroxene) þ quartz. Yoshino et al. (1998) classified zoning patterns of Al in ...
Subduction factory 2. Are intermediate
... observations imply that dehydration in subducting slabs could cause seismicity. Connolly [1997] and Hacker [1997] have emphasized that even reactions with a negative total volume change can lead to elevated fluid pressures over the timescale at which the rock can creep or become sealed. [12] As an o ...
... observations imply that dehydration in subducting slabs could cause seismicity. Connolly [1997] and Hacker [1997] have emphasized that even reactions with a negative total volume change can lead to elevated fluid pressures over the timescale at which the rock can creep or become sealed. [12] As an o ...
SUBMIT_1
... geological history, which caused intense erosion of early formed strata and generally distributed unconformity in North Africa . Hercynian fold belts were formed at northern and southern Africa, where foreland basins and intermountain basins developed along those two fold belts. After the end of Her ...
... geological history, which caused intense erosion of early formed strata and generally distributed unconformity in North Africa . Hercynian fold belts were formed at northern and southern Africa, where foreland basins and intermountain basins developed along those two fold belts. After the end of Her ...
Plate tectonic reconstructions and - Archimer
... The good fit between the ECMA and WACMA lineations, even if their amplitudes significantly differ not only along strikes but also on each side of the central Atlantic Ocean, suggests that the two features are conjugate and thus can be used as isochrons for plate kinematic reconstructions. Louden et ...
... The good fit between the ECMA and WACMA lineations, even if their amplitudes significantly differ not only along strikes but also on each side of the central Atlantic Ocean, suggests that the two features are conjugate and thus can be used as isochrons for plate kinematic reconstructions. Louden et ...
High resolution image of the subducted Paci¢c (?) plate beneath
... on the depths of eclogitization. Teleseismic converted phases permit a direct method to image slab structure, and they have been used to image layering in slabs beneath central Oregon and the central Andes. Beneath Cascadia a prominent low velocity layer is observed to 45 km depth and is interpreted ...
... on the depths of eclogitization. Teleseismic converted phases permit a direct method to image slab structure, and they have been used to image layering in slabs beneath central Oregon and the central Andes. Beneath Cascadia a prominent low velocity layer is observed to 45 km depth and is interpreted ...
The Deadliest Tsunami in History
... Survivors of the Indian Ocean tsunami reported that the sea surged out as fast and as powerfully as it came ashore. Many people who had survived the wall of water rushing inland were seen being swept out to sea when the ocean retreated. A tsunami is a series of waves, and the first wave may not be t ...
... Survivors of the Indian Ocean tsunami reported that the sea surged out as fast and as powerfully as it came ashore. Many people who had survived the wall of water rushing inland were seen being swept out to sea when the ocean retreated. A tsunami is a series of waves, and the first wave may not be t ...
Uncertainties and implications of the Late Cretaceous and Tertiary
... given past time the relative position can be described mathematically as the rotation required to bring magnetic anomaly and fracture zone crossings of this age from the second plate into coincidence with those on the first plate. A variety of different techniques have been ...
... given past time the relative position can be described mathematically as the rotation required to bring magnetic anomaly and fracture zone crossings of this age from the second plate into coincidence with those on the first plate. A variety of different techniques have been ...
A selfconsistent model of melting, magma migration and
... Numerical modeling and anMysis are used to investigate the processesleading to the eruption of mantle-derived magma at mid-ocean ridges. Our model includes the following effects: melting due to decompression,magma migration by percolation, and circulation of the mantle driven by both the oceanic pla ...
... Numerical modeling and anMysis are used to investigate the processesleading to the eruption of mantle-derived magma at mid-ocean ridges. Our model includes the following effects: melting due to decompression,magma migration by percolation, and circulation of the mantle driven by both the oceanic pla ...
PNG ON THE MOVE - GPS MONITORING OF PLATE TECTONICS
... Surveying and Land Studies showing some startling results from these surveys. Introduction Papua New Guinea lies in one of the most tectonically and volcanically active regions in the world, a region where the Pacific and Australian Plates collide. Within Papua New Guinea there are also several smal ...
... Surveying and Land Studies showing some startling results from these surveys. Introduction Papua New Guinea lies in one of the most tectonically and volcanically active regions in the world, a region where the Pacific and Australian Plates collide. Within Papua New Guinea there are also several smal ...
Section 5 - Huntington Catholic School
... Earth’s crust is called folding. • Types of Folds Depending on how rock layers deform, different types of folds are made. • The major types of folds are anticlines, synclines, and monoclines. ...
... Earth’s crust is called folding. • Types of Folds Depending on how rock layers deform, different types of folds are made. • The major types of folds are anticlines, synclines, and monoclines. ...
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.