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... 2. When did subduction begin? To understand how new subduction zones form today, we must also consider when and why this tectonic style was established on Earth. It is widely acknowledged that the early Earth was hotter and that there was more mixing of the mantle [1], but this does not require plat ...
... 2. When did subduction begin? To understand how new subduction zones form today, we must also consider when and why this tectonic style was established on Earth. It is widely acknowledged that the early Earth was hotter and that there was more mixing of the mantle [1], but this does not require plat ...
Early Ordovician rifting of Avalonia and birth of the Rheic Ocean: U
... of late Neoproterozoic volcano-sedimentary sequences that are overlain by a Palaeozoic platformal sedimentary succession. Detrital zircons from the Conception Group are dominated by 570–620 Ma ages and contain a significant component generated by erosion of coeval igneous arc-volcanic rocks. Overlyi ...
... of late Neoproterozoic volcano-sedimentary sequences that are overlain by a Palaeozoic platformal sedimentary succession. Detrital zircons from the Conception Group are dominated by 570–620 Ma ages and contain a significant component generated by erosion of coeval igneous arc-volcanic rocks. Overlyi ...
Upper mantle flow in the western Mediterranean
... Maghrebides subduction started, nucleating along the Alps–Betics retrobelt and possibly triggered by the occurrence, in the foreland east of the Alpine belt, of oceanic or thinned continental lithosphere [6]. The Apennines–Maghrebides subduction zone was characterized, since the beginning, by fast r ...
... Maghrebides subduction started, nucleating along the Alps–Betics retrobelt and possibly triggered by the occurrence, in the foreland east of the Alpine belt, of oceanic or thinned continental lithosphere [6]. The Apennines–Maghrebides subduction zone was characterized, since the beginning, by fast r ...
Top driven asymmetric mantle convection
... The volumes of lithospheric loss must be compensated by the same amount of mantle upwelling. If there are 306 km3/yr of lithospheric loss, we expect the same amount of lithospheric production. New oceanic lithosphere is formed along the about 60,000 km long oceanic ridges and backarc basin systems. ...
... The volumes of lithospheric loss must be compensated by the same amount of mantle upwelling. If there are 306 km3/yr of lithospheric loss, we expect the same amount of lithospheric production. New oceanic lithosphere is formed along the about 60,000 km long oceanic ridges and backarc basin systems. ...
From mud to granite: The Cooma metamorphic sequence
... metamorphic transformation of the rocks, providing evidence that the metamorphic rocks formed from the sedimentary turbidites (Fig. 2). New metamorphic minerals formed as a consequence of increasing temperature and pressure. Around the township of Cooma, the pressure and temperature conditions are h ...
... metamorphic transformation of the rocks, providing evidence that the metamorphic rocks formed from the sedimentary turbidites (Fig. 2). New metamorphic minerals formed as a consequence of increasing temperature and pressure. Around the township of Cooma, the pressure and temperature conditions are h ...
The heavy noble gas composition of the depleted MORB mantle
... To characterize the heavy noble gas composition of MORBs we present new He, Ne, Ar, and Xe abundances and isotopic compositions from the equatorial Mid-Atlantic Ridge. Both depleted MORBs nominally devoid of plume influence and more enriched MORBs thought to represent the influence of a HIMU mantle pl ...
... To characterize the heavy noble gas composition of MORBs we present new He, Ne, Ar, and Xe abundances and isotopic compositions from the equatorial Mid-Atlantic Ridge. Both depleted MORBs nominally devoid of plume influence and more enriched MORBs thought to represent the influence of a HIMU mantle pl ...
KENT C. CONDIE
... and graduate students in the Earth Sciences. The rapid accumulation of data on plate tectonics, mantle evolution, and the origin of continents in the last decade has necessitated continued updating of the course. The book is written for an advanced undergraduate or graduate student, and it assumes a ...
... and graduate students in the Earth Sciences. The rapid accumulation of data on plate tectonics, mantle evolution, and the origin of continents in the last decade has necessitated continued updating of the course. The book is written for an advanced undergraduate or graduate student, and it assumes a ...
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... isotopic compositions indicating isolation from the asthenosphere for a long time. Nevertheless, distinct isotopic compositions are readily inferred to identify old lithospheric material, which could be the continental crust, lithospheric mantle, or both. Zircon ages can also help distinguish juveni ...
... isotopic compositions indicating isolation from the asthenosphere for a long time. Nevertheless, distinct isotopic compositions are readily inferred to identify old lithospheric material, which could be the continental crust, lithospheric mantle, or both. Zircon ages can also help distinguish juveni ...
Chapter 8 Let`s take it from the top: the crust and upper mantle
... may have crustal thicknesses greater than 20 km. Some of these appear to represent large volumes of material generated at oceanic spreading centers or triple junctions, and a few seem to be continental fragments. Although these anomalously thick crust regions constitute only about 10% of the area of ...
... may have crustal thicknesses greater than 20 km. Some of these appear to represent large volumes of material generated at oceanic spreading centers or triple junctions, and a few seem to be continental fragments. Although these anomalously thick crust regions constitute only about 10% of the area of ...
From oceanic plateaus to allochthonous terranes: Numerical
... the Caribbean (Kerr et al., 1997; Kerr and Tarney, 2005) are believed to have formed through extensive accretion along its active margin. Schubert and Sandwell (1989) have estimated an upper bound to the continental crust addition rate by the accretion of all oceanic plateaus to be 3.7 km3/year, whi ...
... the Caribbean (Kerr et al., 1997; Kerr and Tarney, 2005) are believed to have formed through extensive accretion along its active margin. Schubert and Sandwell (1989) have estimated an upper bound to the continental crust addition rate by the accretion of all oceanic plateaus to be 3.7 km3/year, whi ...
Crustal contamination of mafic magmas: evidence from a
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
Continental Growth and Recycling in Convergent Orogens with
... basement are accreted to continents represent important sites of continental crustal growth and recycling. Crust accreted in these settings is dominated by an upper layer of recycled crustal and arc detritus (turbidites) underlain by a layer of tectonically imbricated upper oceanic crust and/or thin ...
... basement are accreted to continents represent important sites of continental crustal growth and recycling. Crust accreted in these settings is dominated by an upper layer of recycled crustal and arc detritus (turbidites) underlain by a layer of tectonically imbricated upper oceanic crust and/or thin ...
Cenozoic magmatism in the western Ross Embayment:
... Wilson [1963] and Morgan [1971], plume occurrence has been frequently postulated just on the basis of magma chemistry, and plume theory has been stretched to the point that at least in some instances simpler explanations can be found. This controversy should be addressed in an integrated geological ...
... Wilson [1963] and Morgan [1971], plume occurrence has been frequently postulated just on the basis of magma chemistry, and plume theory has been stretched to the point that at least in some instances simpler explanations can be found. This controversy should be addressed in an integrated geological ...
Intracratonic asthenosphere upwelling and lithosphere rejuvenation
... generated, by asthenospheric upwelling dominated by the presence of an HIMU signature. Accordingly, this rejuvenated lithosphere (accreted asthenosphere without any EM influence), may represent an appropriate mantle section from which deep alkaline basic melts could have been generated and shallower ...
... generated, by asthenospheric upwelling dominated by the presence of an HIMU signature. Accordingly, this rejuvenated lithosphere (accreted asthenosphere without any EM influence), may represent an appropriate mantle section from which deep alkaline basic melts could have been generated and shallower ...
joseph barrell - National Academy of Sciences
... Washington. He had but two sons, and one of them, John, also a cooper by trade, married Mary, daughter of William Colburn, one of the twelve original founders of the colony. It is from this union that all of the American Barrells of colonial origin have sprung. Until recently, the Barrells have been ...
... Washington. He had but two sons, and one of them, John, also a cooper by trade, married Mary, daughter of William Colburn, one of the twelve original founders of the colony. It is from this union that all of the American Barrells of colonial origin have sprung. Until recently, the Barrells have been ...
A2 Course Study Guide
... uncertain – it is impossible after all to get into a magma chamber with experimental instruments. Molten silicate rock is physically different from the liquid water that results when ice is melted. Pure water consists only of simple molecules of H2O, and therefore ice melts (and freezes) at atmosphe ...
... uncertain – it is impossible after all to get into a magma chamber with experimental instruments. Molten silicate rock is physically different from the liquid water that results when ice is melted. Pure water consists only of simple molecules of H2O, and therefore ice melts (and freezes) at atmosphe ...
EARTH SCIENCE SOL REVIEW - Augusta County Public Schools
... small area in contact with an igneous intrusion “bakes” the rock and changes it. Regional metamorphism— large area changed due to heat and pressure. Usually with mountains. ...
... small area in contact with an igneous intrusion “bakes” the rock and changes it. Regional metamorphism— large area changed due to heat and pressure. Usually with mountains. ...
geologic map (scale 1 :250000) of the penokean orogen, central
... Finally, the region henceforth referred to as the foldand-thrust belt (Fig. 1) contains a much larger proportion of volcanic rocks than was heretofore realized. Sizable areas formerly thought to be underlain by metasedimentary rocks or granitoid gneiss, because of their subdued magnetic signature, a ...
... Finally, the region henceforth referred to as the foldand-thrust belt (Fig. 1) contains a much larger proportion of volcanic rocks than was heretofore realized. Sizable areas formerly thought to be underlain by metasedimentary rocks or granitoid gneiss, because of their subdued magnetic signature, a ...
Mountain Building Web Activity
... The Caucasus Mountains are located between the Black Sea and Caspian Sea, separating Europe from Asia. This 550-mile long mountain range lies between Russia to the north and the countries of Georgia, Azerbajian and Armenia to the south. With an average elevation of 6000-9000 feet (~1800-2700 meters) ...
... The Caucasus Mountains are located between the Black Sea and Caspian Sea, separating Europe from Asia. This 550-mile long mountain range lies between Russia to the north and the countries of Georgia, Azerbajian and Armenia to the south. With an average elevation of 6000-9000 feet (~1800-2700 meters) ...
U-Pb MINERAL AGE DETERMINATIONS FROM ARCHEAN ROCKS
... The Lomperovaara tonalite within the Vintilänkaira-Kemihaara complex and syenitic rocks cross-cutting the Tulppio metavolcanic belt have minimum zircon ages of c. 2.80 Ga, and a hornblende-gneiss inclusion within the Lomperovaara tonalite gives the same 2.83 Ga as a tonalite of the Ahmatunturi compl ...
... The Lomperovaara tonalite within the Vintilänkaira-Kemihaara complex and syenitic rocks cross-cutting the Tulppio metavolcanic belt have minimum zircon ages of c. 2.80 Ga, and a hornblende-gneiss inclusion within the Lomperovaara tonalite gives the same 2.83 Ga as a tonalite of the Ahmatunturi compl ...
Patagonia: where does it come from?
... is proposed that the Somuncurá Massif of northern Patagonia is the conjugate margin of the Pensacola Mountains in East Antarctica. The main episodes of deformation within the Cambrian-Ordovician Ross Orogeny are correlated, as well as the passive margin setting during the Silurian-Devonian, which in ...
... is proposed that the Somuncurá Massif of northern Patagonia is the conjugate margin of the Pensacola Mountains in East Antarctica. The main episodes of deformation within the Cambrian-Ordovician Ross Orogeny are correlated, as well as the passive margin setting during the Silurian-Devonian, which in ...
Depleted lithosphere, cold, trapped asthenosphere, and frozen melt
... shallow anomaly distinguished by its very low P- and S-wave velocities and its moderately high Vp / Vs ratio. We interpret these anomalies to represent very depleted cold lithosphere, cooled trapped asthenosphere, and frozen pooled melt, respectively. Recent research looking at the elastic propertie ...
... shallow anomaly distinguished by its very low P- and S-wave velocities and its moderately high Vp / Vs ratio. We interpret these anomalies to represent very depleted cold lithosphere, cooled trapped asthenosphere, and frozen pooled melt, respectively. Recent research looking at the elastic propertie ...
Continent-sized anomalous zones with low
... he movement of Earth’s tectonic plates, which includes divergence at mid-ocean ridges to create new crust and lithosphere, as well as convergence and consumption of older plates into Earth’s interior at subduction zones, is related to convective motions of the underlying mantle rock over geologic ti ...
... he movement of Earth’s tectonic plates, which includes divergence at mid-ocean ridges to create new crust and lithosphere, as well as convergence and consumption of older plates into Earth’s interior at subduction zones, is related to convective motions of the underlying mantle rock over geologic ti ...
3 - Blinklearning
... 1.1. The origin of the Earth Before starting this section, remind students about the concepts of density and gravity. It will help them to understand clearly the origin of our planet. It is important that students differentiate the concepts of density and mass. Otherwise, they will not be able to un ...
... 1.1. The origin of the Earth Before starting this section, remind students about the concepts of density and gravity. It will help them to understand clearly the origin of our planet. It is important that students differentiate the concepts of density and mass. Otherwise, they will not be able to un ...
Composition of the depleted mantle
... 1985]. One possibility is that the DM is an open system whereby U, Th and Pb have different exchange rates, and therefore have different residence times in non-DM mantle and CC [Galer et al., 1989; Galer and O’Nions, 1985; Paul et al., 2002]. A second class of models argues that the discrepancy betw ...
... 1985]. One possibility is that the DM is an open system whereby U, Th and Pb have different exchange rates, and therefore have different residence times in non-DM mantle and CC [Galer et al., 1989; Galer and O’Nions, 1985; Paul et al., 2002]. A second class of models argues that the discrepancy betw ...
History of Earth
The history of Earth concerns the development of the planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span.Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere, but it contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. One very large collision is thought to have been responsible for tilting the Earth at an angle and forming the Moon. Over time, the planet cooled and formed a solid crust, allowing liquid water to exist on the surface.The first life forms appeared between 3.8 and 3.5 billion years ago. The earliest evidences for life on Earth are graphite found to be biogenic in 3.7-billion-year-old metasedimentary rocks discovered in Western Greenland and microbial mat fossils found in 3.48-billion-year-old sandstone discovered in Western Australia. Photosynthetic life appeared around 2 billion years ago, enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose. During the Cambrian period it experienced a rapid diversification into most major phyla. More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described.Geological change has been constantly occurring on Earth since the time of its formation and biological change since the first appearance of life. Species continuously evolve, taking on new forms, splitting into daughter species, or going extinct in response to an ever-changing planet. The process of plate tectonics has played a major role in the shaping of Earth's oceans and continents, as well as the life they harbor. The biosphere, in turn, has had a significant effect on the atmosphere and other abiotic conditions on the planet, such as the formation of the ozone layer, the proliferation of oxygen, and the creation of soil.