Lecture W6-L15-17
... country rock. This can be at different levels depending on the nature of the magma (and the crust): base of the continental crust for basalts in continental settings, somewhere into the crust for continental granites … or above the surface for oceanic rocks! Lack of pathways, hindering the upwards m ...
... country rock. This can be at different levels depending on the nature of the magma (and the crust): base of the continental crust for basalts in continental settings, somewhere into the crust for continental granites … or above the surface for oceanic rocks! Lack of pathways, hindering the upwards m ...
Pangaea to Plate Tectonics Report
... sun, not that everything moves around earth]. Within a matter of only several years geophysics and geology in particular were revolutionized. . . . What had been rejected for decades by any respectable scientific journal was eagerly accepted within a few short years in the 1960s and 1970s.2 These st ...
... sun, not that everything moves around earth]. Within a matter of only several years geophysics and geology in particular were revolutionized. . . . What had been rejected for decades by any respectable scientific journal was eagerly accepted within a few short years in the 1960s and 1970s.2 These st ...
Fulltext - ETH E
... change from a relatively deep Moho (down to 42 km) below the Atlas Mountain Range to the thin crust of the southwestern Mediterranean Sea has been found. The crust beneath the eastern North Atlantic Ocean can be up to 5 km thicker compared to standard oceanic crust (6 km). Serpentinization of the su ...
... change from a relatively deep Moho (down to 42 km) below the Atlas Mountain Range to the thin crust of the southwestern Mediterranean Sea has been found. The crust beneath the eastern North Atlantic Ocean can be up to 5 km thicker compared to standard oceanic crust (6 km). Serpentinization of the su ...
The Laramide Orogeny: What Were the Driving Forces?
... plates, separated by a spreading center, were subducting beneath western North America during Laramide time (e.g., Engebretson et al., 1985; Kelley, 1993), although the location of the Kula– Farallon–North America triple junction during Laramide time remains a matter of much debate (e.g., Breitsprec ...
... plates, separated by a spreading center, were subducting beneath western North America during Laramide time (e.g., Engebretson et al., 1985; Kelley, 1993), although the location of the Kula– Farallon–North America triple junction during Laramide time remains a matter of much debate (e.g., Breitsprec ...
Hunting for oceanic island Moho
... In addition, the application of the Zhu and Kanamori method to our RFs assuming a single-layered crust resulted in three different solutions for crustal thickness. This indicates the presence of three well-defined interfaces below the surface with physical differences (potentially compositional or f ...
... In addition, the application of the Zhu and Kanamori method to our RFs assuming a single-layered crust resulted in three different solutions for crustal thickness. This indicates the presence of three well-defined interfaces below the surface with physical differences (potentially compositional or f ...
Variations in magmatic processes along the East Greenland
... Seismic velocities and the associated thicknesses of rifted and igneous crust provide key constraints on the rifting history, the differentiation between non-volcanic and volcanic rifted margins, the driving force of magmatism at volcanic margins, that is, active or passive upwelling and the tempera ...
... Seismic velocities and the associated thicknesses of rifted and igneous crust provide key constraints on the rifting history, the differentiation between non-volcanic and volcanic rifted margins, the driving force of magmatism at volcanic margins, that is, active or passive upwelling and the tempera ...
Becker, T. W. - The University of Texas at Austin
... inference of dynamic topography, based on filtered free-air gravity (following Craig et al., 2011), shown in black. We ask if lithospheric thickness variations are sufficient to explain the residual Atlas topography. Such a model is plotted as the dashed red curve of Figure 3C, assuming that all res ...
... inference of dynamic topography, based on filtered free-air gravity (following Craig et al., 2011), shown in black. We ask if lithospheric thickness variations are sufficient to explain the residual Atlas topography. Such a model is plotted as the dashed red curve of Figure 3C, assuming that all res ...
Kohlstedt answers PDF
... The primary field observations have been at mid-ocean ridges. The National Science Foundation supported an extensive investigation of spreading centers in the 1990s into the early 2000s. So we know a lot about these regions. A similar effort is in progress for subductions zones. Maybe we will find s ...
... The primary field observations have been at mid-ocean ridges. The National Science Foundation supported an extensive investigation of spreading centers in the 1990s into the early 2000s. So we know a lot about these regions. A similar effort is in progress for subductions zones. Maybe we will find s ...
An olivine-free mantle source of Hawaiian shield basalts
... More than 50 per cent of the Earth’s upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent wit ...
... More than 50 per cent of the Earth’s upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent wit ...
Making mushy magma chambers in the lower continental crust: Cold
... Increasing geological and geophysical evidence suggests that crustal magma reservoirs are normally low melt fraction ‘mushes’ rather than high melt fraction ‘magma chambers’. Yet high melt fractions must form within these mush reservoirs to explain the observed flow and eruption of low crystallinity ...
... Increasing geological and geophysical evidence suggests that crustal magma reservoirs are normally low melt fraction ‘mushes’ rather than high melt fraction ‘magma chambers’. Yet high melt fractions must form within these mush reservoirs to explain the observed flow and eruption of low crystallinity ...
An olivine-free mantle source of Hawaiian shield
... More than 50 per cent of the Earth’s upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent wit ...
... More than 50 per cent of the Earth’s upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent wit ...
Alignment between seafloor spreading directions and absolute plate
... state of the upper mantle. Becker et al. [2015] further suggested that minimizing the global misfit between APM and spreading direction at ridges defines a comprehensive reference frame. They showed that such an APM model matches seismic anisotropy, satisfies trench migration rates, and has a best fitti ...
... state of the upper mantle. Becker et al. [2015] further suggested that minimizing the global misfit between APM and spreading direction at ridges defines a comprehensive reference frame. They showed that such an APM model matches seismic anisotropy, satisfies trench migration rates, and has a best fitti ...
A new concept of continental construction in the Central Asian
... accumulated against a few magmatic arcs of extended length. The Kemp et al., 2006; Hawkesworth et al., 2010). Have some researchers underestimated the amount of Phanerozoic crustal growth because most of recent geological, tectonic, geodynamic and metallogenic maps and reconstructions of the CAOB ar ...
... accumulated against a few magmatic arcs of extended length. The Kemp et al., 2006; Hawkesworth et al., 2010). Have some researchers underestimated the amount of Phanerozoic crustal growth because most of recent geological, tectonic, geodynamic and metallogenic maps and reconstructions of the CAOB ar ...
Lithosphere, Earth`s Interior and Paleo-Environment
... that extend for several hundreds of kilometers in length. The Great Dyke of Zimbabwe in South Africa and the Abitibi Great Dyke in the Canadian shield extend for about 550 – 600 kilometers. Similarly a gabbroic to dolerite dyke in Peninsular India extending for nearly 450 kilometers in a NNW directi ...
... that extend for several hundreds of kilometers in length. The Great Dyke of Zimbabwe in South Africa and the Abitibi Great Dyke in the Canadian shield extend for about 550 – 600 kilometers. Similarly a gabbroic to dolerite dyke in Peninsular India extending for nearly 450 kilometers in a NNW directi ...
View - GFZpublic
... 2.1 Propagation of seismic rays through the Earth and the formation of seismic records NMSOP-2 offers 10 animations which show the propagation of seismic rays of different seismic phases through the Earth as well as the formation of seismic records of these waves from earthquakes at different depth ...
... 2.1 Propagation of seismic rays through the Earth and the formation of seismic records NMSOP-2 offers 10 animations which show the propagation of seismic rays of different seismic phases through the Earth as well as the formation of seismic records of these waves from earthquakes at different depth ...
The Southern End of the Pacific Ring of Fire: Quaternary Volcanism
... attributed to a combination of thin crust, high heat flow, and an extensional tectonic regime; and has been described as a rifting arc (Wilson et al. 1995a, 2009). Current extension rates range from *15 mm/year in the north to *5 mm/year in the south (Wallace et al. 2004). Oblique subduction of the ...
... attributed to a combination of thin crust, high heat flow, and an extensional tectonic regime; and has been described as a rifting arc (Wilson et al. 1995a, 2009). Current extension rates range from *15 mm/year in the north to *5 mm/year in the south (Wallace et al. 2004). Oblique subduction of the ...
The transition from diffuse to focused extension: Modeled evolution
... Paleogene time and ended by ∼ 26 Ma. This stage of extension was focused primarily within the Victoria Land Basin near the boundary with East Antarctica, and ultimately led to development of the Terror Rift. It is possible that there was an extensional hiatus between 80 Ma and early Paleogene time, ...
... Paleogene time and ended by ∼ 26 Ma. This stage of extension was focused primarily within the Victoria Land Basin near the boundary with East Antarctica, and ultimately led to development of the Terror Rift. It is possible that there was an extensional hiatus between 80 Ma and early Paleogene time, ...
Oxygen-isotope and trace element constraints on the origins of silica
... et al., 1995], and thus they could have bearing on the petrogenesis of the lavas that carried the xenoliths to the surface. These melt inclusions clearly existed in the mantle and so cannot be products of differentiation in or partial melting of the arc crust (though they could be products of differ ...
... et al., 1995], and thus they could have bearing on the petrogenesis of the lavas that carried the xenoliths to the surface. These melt inclusions clearly existed in the mantle and so cannot be products of differentiation in or partial melting of the arc crust (though they could be products of differ ...
2011 - University of Colorado Boulder
... but three higher resolution models are also computed (Table 2). Considering the important effects of seafloor age on the surface heat flux (e.g., Lister, 1977; Parsons, 1982), we quantify seafloor age distribution at different times in our models. Seafloor age calculation is only dependent on the plate ...
... but three higher resolution models are also computed (Table 2). Considering the important effects of seafloor age on the surface heat flux (e.g., Lister, 1977; Parsons, 1982), we quantify seafloor age distribution at different times in our models. Seafloor age calculation is only dependent on the plate ...
Rheology and strength of the lithosphere - Evgueni Burov
... by slow visco-elastic relaxation, in contrast to the underlying, relatively low viscosity asthenosphere. The long-term mechanical base of the lithosphere, hm, is limited by the depth to the 500e600 C isotherm in oceans and the 700e800 C isotherm in continents, while the base of the thermal litho ...
... by slow visco-elastic relaxation, in contrast to the underlying, relatively low viscosity asthenosphere. The long-term mechanical base of the lithosphere, hm, is limited by the depth to the 500e600 C isotherm in oceans and the 700e800 C isotherm in continents, while the base of the thermal litho ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.