Lithosphere delamination in continental collisional orogens: A
... We used a large-scale model domain (4000 × 400 km) to study the dynamics of continental collision and lithosphere delamination. Using a nonuniform rectangular numerical grid, we represent the collision zone with a 1 × 1 km high resolution while using a 5 × 1 km for the rest of the model domain. A de ...
... We used a large-scale model domain (4000 × 400 km) to study the dynamics of continental collision and lithosphere delamination. Using a nonuniform rectangular numerical grid, we represent the collision zone with a 1 × 1 km high resolution while using a 5 × 1 km for the rest of the model domain. A de ...
Elevated 87Sr/86Sr Ratios From Mafic Intrusions in the Atlanta Lobe
... plutons show deeper levels of exposure than do plutons from the better studied Sierran Nevada batholith. Additional work on the border zone rocks of the Atlanta lobe includes regional summaries and reconnaissance studies by Anderson (1952), Larsen and Schmidt (1958), Schmidt (1964), Taubeneck (1971) ...
... plutons show deeper levels of exposure than do plutons from the better studied Sierran Nevada batholith. Additional work on the border zone rocks of the Atlanta lobe includes regional summaries and reconnaissance studies by Anderson (1952), Larsen and Schmidt (1958), Schmidt (1964), Taubeneck (1971) ...
nature and composition of the continental crust
... energy at very small offsets (2-10 km), small receiver spacing (25-100 m), and close shot spacing (50-500 m) relative to refraction surveys. Although subcritical reflections have lower amplitudes than critical to supercritical reflections, the acquisition geometry produces a data redundancy that per ...
... energy at very small offsets (2-10 km), small receiver spacing (25-100 m), and close shot spacing (50-500 m) relative to refraction surveys. Although subcritical reflections have lower amplitudes than critical to supercritical reflections, the acquisition geometry produces a data redundancy that per ...
Supercontinents, mantle dynamics and plate
... been challenged in recent works and current models propose that plate tectonics creates and destroys Earth's continental crust with more crust being destroyed than created. The creation–destruction balance changes over a supercontinent cycle, with a higher crustal growth through magmatic influx durin ...
... been challenged in recent works and current models propose that plate tectonics creates and destroys Earth's continental crust with more crust being destroyed than created. The creation–destruction balance changes over a supercontinent cycle, with a higher crustal growth through magmatic influx durin ...
Hotspots and Melting Anomalies - Earth and Environmental Sciences
... An intriguing, yet enigmatic form of age-progressive volcanism is represented by the PukaPuka and Sojourn Ridges, which extend NW away from the East Pacific Rise. With respect to its geographic trend and duration, the Puka-Puka Ridge resembles some of the other volcano chains the region, such as the ...
... An intriguing, yet enigmatic form of age-progressive volcanism is represented by the PukaPuka and Sojourn Ridges, which extend NW away from the East Pacific Rise. With respect to its geographic trend and duration, the Puka-Puka Ridge resembles some of the other volcano chains the region, such as the ...
Not Getting the Drift - Personal webpages at NTNU
... mountains could influence climate both locally and globally. If continents are suitably arranged, warm ocean currents such as the Gulf Stream can bring mild climate to high northern latitudes. The opposite result is also possible. Snow-covered lands and icecovered oceans will reflect solar rays, and ...
... mountains could influence climate both locally and globally. If continents are suitably arranged, warm ocean currents such as the Gulf Stream can bring mild climate to high northern latitudes. The opposite result is also possible. Snow-covered lands and icecovered oceans will reflect solar rays, and ...
An introduction to magma dynamics Geological Society, London
... parts of the crustal plumbing system that are best elucidated by the samples or methods available. It is rare that systems have been studied in sufficient detail to inform the entire process from magma generation in the mantle to eruption at the surface. This book starts with two studies where the a ...
... parts of the crustal plumbing system that are best elucidated by the samples or methods available. It is rare that systems have been studied in sufficient detail to inform the entire process from magma generation in the mantle to eruption at the surface. This book starts with two studies where the a ...
Practice Exam - Georgia State University
... ____ 63. In the 1800s Lord Kelvin estimated the age of the Earth, utilizing a number of assumptions. Which wrong assumption was the primary reason why his estimate (approximately 20 million years) was so wildly inaccurate? a. that the Earth was once hotter than it presently is today b. that the Eart ...
... ____ 63. In the 1800s Lord Kelvin estimated the age of the Earth, utilizing a number of assumptions. Which wrong assumption was the primary reason why his estimate (approximately 20 million years) was so wildly inaccurate? a. that the Earth was once hotter than it presently is today b. that the Eart ...
G. Heinson, Electromagnetic studies of the lithosphere and
... when the essential scientific aim in interpreting and relating observable quantities has been achieved by the assignment of a material property, what further scientific purpose, if any, is being served by efforts to reinterpret it as the value of a function depending on an ill-defined number of unob ...
... when the essential scientific aim in interpreting and relating observable quantities has been achieved by the assignment of a material property, what further scientific purpose, if any, is being served by efforts to reinterpret it as the value of a function depending on an ill-defined number of unob ...
Temporal variation in relative zircon abundance throughout Earth
... a consequence of secular mantle cooling, where lower average mantle melting extent has led to increased average concentrations of incompatible elements such as Zr (Keller and Schoene, 2012), and generally lower M values due to lower Ca and higher Al abundance. Combined, these forcings should result ...
... a consequence of secular mantle cooling, where lower average mantle melting extent has led to increased average concentrations of incompatible elements such as Zr (Keller and Schoene, 2012), and generally lower M values due to lower Ca and higher Al abundance. Combined, these forcings should result ...
Some remarks on subduction zones - Dipartimento di Scienze della
... Is the slab pull the energetic source for plate motions? Is it large enough? Is it correctly calculated? Are the assumptions reliable? Most of the literature indicates that the slab pull is about 3.3x1013 N m-1 (e.g., Turcotte and Schubert, 2002). This is a force per unit length parallel to the tren ...
... Is the slab pull the energetic source for plate motions? Is it large enough? Is it correctly calculated? Are the assumptions reliable? Most of the literature indicates that the slab pull is about 3.3x1013 N m-1 (e.g., Turcotte and Schubert, 2002). This is a force per unit length parallel to the tren ...
emplacement of viscous mushes in the jinchuan ultramafic
... China, is currently a dyke-like body, dominated by olivine-rich ultramafic rocks containing disseminated sulfides. It was discovered in 1958, and follow-up exploration proved that the intrusion hosted as much as half a billion tonnes of net-textured, disseminated and subordinate massive Ni–Cu–PGE su ...
... China, is currently a dyke-like body, dominated by olivine-rich ultramafic rocks containing disseminated sulfides. It was discovered in 1958, and follow-up exploration proved that the intrusion hosted as much as half a billion tonnes of net-textured, disseminated and subordinate massive Ni–Cu–PGE su ...
alleghanian plutonism in the eastern blue ridge
... oceanic lithosphere is unknown but may be recorded in Carboniferous magmatism recently discovered in the southern Appalachians. The four Alleghanian plutons located in the eastern Blue Ridge are the oldest of the Alleghanian plutons and predate the estimated collision ca. 330 Ma. These plutons have ...
... oceanic lithosphere is unknown but may be recorded in Carboniferous magmatism recently discovered in the southern Appalachians. The four Alleghanian plutons located in the eastern Blue Ridge are the oldest of the Alleghanian plutons and predate the estimated collision ca. 330 Ma. These plutons have ...
Mantle-driven deformation of orogenic zones and clutch tectonics
... The upper crust is the best-studied lithospheric layer in terms of deformation. Deformation is both aseismic and seismic, and the bulk rheology is mostly characterized by Coulomb behaviour. The deformation mechanisms for upper crustal deformation are cataclastic flow, pressure solution and dislocati ...
... The upper crust is the best-studied lithospheric layer in terms of deformation. Deformation is both aseismic and seismic, and the bulk rheology is mostly characterized by Coulomb behaviour. The deformation mechanisms for upper crustal deformation are cataclastic flow, pressure solution and dislocati ...
Relationship between Moldanubicum, the Kutn· Hora Crystalline
... were studied using CAMEBAX microanalyser (operator J. Hovorka) at the Faculty of Science, Charles University, Prague. Mineral analyses were performed with the use of CAMEBAX microanalyser (operator J. Hovorka) at the following parameters: accelerating voltage 15 kV, current 22 µA, t = 10 s. Mineral ...
... were studied using CAMEBAX microanalyser (operator J. Hovorka) at the Faculty of Science, Charles University, Prague. Mineral analyses were performed with the use of CAMEBAX microanalyser (operator J. Hovorka) at the following parameters: accelerating voltage 15 kV, current 22 µA, t = 10 s. Mineral ...
Economic geology research, volume 1 1999-2000
... minor mafic volcanic rocks is generally considered to overlie the submarine Skellefte Group of volcanic rocks. The Arvidsjaur Group volcanic rocks are also considered to underlie the Ledfat Group of conglomerates and sandstones. The Arvidsjaur Group has been poorly dated at 1878±2 Ma (Skiöld et al. ...
... minor mafic volcanic rocks is generally considered to overlie the submarine Skellefte Group of volcanic rocks. The Arvidsjaur Group volcanic rocks are also considered to underlie the Ledfat Group of conglomerates and sandstones. The Arvidsjaur Group has been poorly dated at 1878±2 Ma (Skiöld et al. ...
︎PDF - Fabio Crameri
... been advected down into the subduction zone is thought to be key in inducing realistic, single-sided subduction by providing lubrication at the plate interface [Lenardic and Kaula, 1994; Tagawa et al., 2007; Gerya et al., 2008; Crameri et al., 2012a; Duarte et al., 2013; Dymkova and Gerya, 2013]. Th ...
... been advected down into the subduction zone is thought to be key in inducing realistic, single-sided subduction by providing lubrication at the plate interface [Lenardic and Kaula, 1994; Tagawa et al., 2007; Gerya et al., 2008; Crameri et al., 2012a; Duarte et al., 2013; Dymkova and Gerya, 2013]. Th ...
PDF
... 1464-343X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jafrearsci.2011.07.003 ...
... 1464-343X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jafrearsci.2011.07.003 ...
Late Palaeozoic lam pro phyres and as so ci ated mafic subvolcanic
... 1:25 000” (Polish Geological Institute, 1954–1994; references are given in the caption to Fig. 2). In addition, selected outcrops of associated hypabyssal mafic rocks were also sampled. The general term “mafic rocks” is used in this paper for rocks rich in mafic minerals; “felsic rocks”, such as var ...
... 1:25 000” (Polish Geological Institute, 1954–1994; references are given in the caption to Fig. 2). In addition, selected outcrops of associated hypabyssal mafic rocks were also sampled. The general term “mafic rocks” is used in this paper for rocks rich in mafic minerals; “felsic rocks”, such as var ...
Tourmaline Isotopes: No Element Left Behind
... hypothesis is important for studies of ancient crust, where most of the evidence of active continental margins has been lost to erosion and detrital grains in sediments may remain the sole geologic witnesses. Tourmaline is a stable detrital mineral and is relatively abundant in mature clastic sedime ...
... hypothesis is important for studies of ancient crust, where most of the evidence of active continental margins has been lost to erosion and detrital grains in sediments may remain the sole geologic witnesses. Tourmaline is a stable detrital mineral and is relatively abundant in mature clastic sedime ...
Rhenium^Osmium Isotope and Platinum-Group Element
... as the Keel feeder dyke (Fig. 3). Aeromagnetic and gravity anomaly studies show the intrusion extends northward for at least 250 km under younger cover where it becomes more laterally extensive (Fig. 1). The present exposure probably represents a thin, oblique slice through a much larger intrusion ( ...
... as the Keel feeder dyke (Fig. 3). Aeromagnetic and gravity anomaly studies show the intrusion extends northward for at least 250 km under younger cover where it becomes more laterally extensive (Fig. 1). The present exposure probably represents a thin, oblique slice through a much larger intrusion ( ...
Tethyan closure, Andean orogeny, and westward drift of the Pacific
... Although global mantle flow models based on seismic tomography (Zhong, 2001; Becker, 2006) can reproduce the westward direction of the observed HS3 (Gripp and Gordon, 2002) net rotation, they generally do not reproduce the 48 mm/yr amplitude of this rotation. Instead, the maximum amplitude of the pre ...
... Although global mantle flow models based on seismic tomography (Zhong, 2001; Becker, 2006) can reproduce the westward direction of the observed HS3 (Gripp and Gordon, 2002) net rotation, they generally do not reproduce the 48 mm/yr amplitude of this rotation. Instead, the maximum amplitude of the pre ...
Anderson and Natland, 2005
... same data can be, and have been, used in support of other mechanisms, such as propagating fractures, membrane stresses, and sequential volcanic loading, they will likewise not be discussed. Age-progressive volcanism is not uniquely diagnostic of a plume. Clague and Dalrymple (1987, 1989), Koppers et ...
... same data can be, and have been, used in support of other mechanisms, such as propagating fractures, membrane stresses, and sequential volcanic loading, they will likewise not be discussed. Age-progressive volcanism is not uniquely diagnostic of a plume. Clague and Dalrymple (1987, 1989), Koppers et ...
Age of the Earth
The age of the Earth is 4.54 ± 0.05 billion years (4.54 × 109 years ± 1%). This age is based on evidence from radiometric age dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.Following the development of radiometric age dating in the early 20th century, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old.The oldest such minerals analyzed to date—small crystals of zircon from the Jack Hills of Western Australia—are at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to those of other stars, it appears that the Solar System cannot be much older than those rocks. Calcium-aluminium-rich inclusions – the oldest known solid constituents within meteorites that are formed within the Solar System – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of Earth.It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites. Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few millions up to about 100 million years, the exact age of Earth is difficult to determine. It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages.