Generation of new continental crust by sublithospheric silicic
... andesite magmas are formed in arc settings, the problem of new crust generation is closely related to the origin of andesite magmas. However, the proportion of andesite to basalt in arcs is a debated topic with the consequence that a bulk andesite composition for arcs has been questioned. This was o ...
... andesite magmas are formed in arc settings, the problem of new crust generation is closely related to the origin of andesite magmas. However, the proportion of andesite to basalt in arcs is a debated topic with the consequence that a bulk andesite composition for arcs has been questioned. This was o ...
The Hindu Kush Seismic Zone as a Paradigm
... of HP or UHP rocks. Despite the lack of evidence for HP or UHP metamorphism during the Himalayan orogeny, many other orogenic belts contain evidence of UHP metamorphism during continent-continent collision (e.g., Dabie Shan–Sulu Belt, Kazakhstan, western Norway, and the Alps). Clearly some mechanism ...
... of HP or UHP rocks. Despite the lack of evidence for HP or UHP metamorphism during the Himalayan orogeny, many other orogenic belts contain evidence of UHP metamorphism during continent-continent collision (e.g., Dabie Shan–Sulu Belt, Kazakhstan, western Norway, and the Alps). Clearly some mechanism ...
Origin of Mesoproterozoic A-type granites in Laurentia
... compositions reflect the relative contributions of mantle and crustal sources in their genesis. In Laurentia, a distinctive belt of Mesoproterozoic A-type or “anorogenic” granites of ∼ 1.4 Ga age was emplaced within composite, heterogeneous Proterozoic crust. Zircons are an ideal mineral to constrai ...
... compositions reflect the relative contributions of mantle and crustal sources in their genesis. In Laurentia, a distinctive belt of Mesoproterozoic A-type or “anorogenic” granites of ∼ 1.4 Ga age was emplaced within composite, heterogeneous Proterozoic crust. Zircons are an ideal mineral to constrai ...
Ophiolites and Their Origins
... Ophiolites are the remnants of ancient oceanic crust the Troodos oceanic crust on Cyprus was a product of and upper mantle that were tectonically emplaced into island arc magmatism. This was a revolutionary but controcontinental margins. They display the only evidence for versial development in the ...
... Ophiolites are the remnants of ancient oceanic crust the Troodos oceanic crust on Cyprus was a product of and upper mantle that were tectonically emplaced into island arc magmatism. This was a revolutionary but controcontinental margins. They display the only evidence for versial development in the ...
A unique lower mantle source for Southern Italy volcanics
... represents the mantle source of the Italian magmatism. Our PCA calculation shows that the first principal component alone, which we take to be a mixture of two geochemical end-members, C and a crustally-derived component, explains 99.4% of the whole data variability. In contrast, the DMM end-member ...
... represents the mantle source of the Italian magmatism. Our PCA calculation shows that the first principal component alone, which we take to be a mixture of two geochemical end-members, C and a crustally-derived component, explains 99.4% of the whole data variability. In contrast, the DMM end-member ...
Becker, T. W. - The University of Texas at Austin
... deformation of the free-surface. We have used this to study lithospheric dynamics in order to gain insights on the present-day conditions of stress and deformation of the lithosphere. Our numerical approach takes the observed topography and far-field plate velocities as input and computes the result ...
... deformation of the free-surface. We have used this to study lithospheric dynamics in order to gain insights on the present-day conditions of stress and deformation of the lithosphere. Our numerical approach takes the observed topography and far-field plate velocities as input and computes the result ...
Endless Voyage 101 - Crafton Hills College
... 6. What did the Glomar Challenger of DSDP (the Deep Sea Drilling Project) do for the development of the sea floor spreading theory? ...
... 6. What did the Glomar Challenger of DSDP (the Deep Sea Drilling Project) do for the development of the sea floor spreading theory? ...
Planetary Atmospheres and Life
... both atmospheric composition and redox state, that is, the balance between reduced and oxidized gases, e.g., H2 and O2. The redox state of volcanic gases is, in turn, influenced by the redox state of Earth’s mantle—a topic that will require us to delve into some aspects of petrology. To motivate our ...
... both atmospheric composition and redox state, that is, the balance between reduced and oxidized gases, e.g., H2 and O2. The redox state of volcanic gases is, in turn, influenced by the redox state of Earth’s mantle—a topic that will require us to delve into some aspects of petrology. To motivate our ...
Geology of Greenland Survey Bulletin 177, 89-95
... implies that it was also generally hotter, simply because cooling of the ocean floor is known to be a very slow process (see e.g. Martin, 1986, 1993; Drummond & Defant, 1990; Tarney & Jones, 1994). Some authors have taken this view even further, suggesting that the heat flow was so high that the upp ...
... implies that it was also generally hotter, simply because cooling of the ocean floor is known to be a very slow process (see e.g. Martin, 1986, 1993; Drummond & Defant, 1990; Tarney & Jones, 1994). Some authors have taken this view even further, suggesting that the heat flow was so high that the upp ...
... preceding observations may also support the interpretation that the conduction of excess heat supply from the elevated hot oceanic upper mantle into the adjacent midto-lower continental crust over a long period of geological time may play an important role in the crustal deformation beneath the cont ...
Origin and evolution of the lower crust in magmatic
... the onset of subduction of more oceanic crust that originally formed above the Galápagos mantle plume. We also find that seismic P-waves travel through the crust at velocities intermediate between those typically observed for oceanic and continental crust. We develop a continentality index to quanti ...
... the onset of subduction of more oceanic crust that originally formed above the Galápagos mantle plume. We also find that seismic P-waves travel through the crust at velocities intermediate between those typically observed for oceanic and continental crust. We develop a continentality index to quanti ...
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... which are best preserved where collision is of moderate intensity. Terminal collision between continents results in intense deformation and erosion that can largely remove ophiolitic suture markers, but even in the case of the severe India-Asia collision there are some ophiolitic fragments to mark t ...
... which are best preserved where collision is of moderate intensity. Terminal collision between continents results in intense deformation and erosion that can largely remove ophiolitic suture markers, but even in the case of the severe India-Asia collision there are some ophiolitic fragments to mark t ...
View - GFZpublic
... age (Hargrove et al., 2006). Most of the AS formed during the Pan‐African orogenic cycle (~1000‐530 Ma) by suturing of juve‐ nile intra‐oceanic arc terrains followed by magmatic thickening, giving rise to regional metamorphism and the generation of batholiths of predominantly ...
... age (Hargrove et al., 2006). Most of the AS formed during the Pan‐African orogenic cycle (~1000‐530 Ma) by suturing of juve‐ nile intra‐oceanic arc terrains followed by magmatic thickening, giving rise to regional metamorphism and the generation of batholiths of predominantly ...
Plate tectonics from space - Laboratoire de Géologie de l`Ecole
... Dan McKenzie) firmly established the basis of the plate tectonics theory—in which plate rigidity was a key element—allowing the calculation of the first global models of plate motion, known as plate "kinematics" (see the history of Plate Tectonics, in Le Pichon, 1991, the first global plate model in ...
... Dan McKenzie) firmly established the basis of the plate tectonics theory—in which plate rigidity was a key element—allowing the calculation of the first global models of plate motion, known as plate "kinematics" (see the history of Plate Tectonics, in Le Pichon, 1991, the first global plate model in ...
Rheological heterogeneity, mechanical anisotropy
... the tectonic behaviour of the lithosphere. Lateral rheological heterogeneity of the continental lithosphere may result from various sources, with variations in geothermal gradient being the principal one. The oldest domains of continents, the cratonic nuclei, are characterized by a relatively cold, ...
... the tectonic behaviour of the lithosphere. Lateral rheological heterogeneity of the continental lithosphere may result from various sources, with variations in geothermal gradient being the principal one. The oldest domains of continents, the cratonic nuclei, are characterized by a relatively cold, ...
The role of lower continental crust and lithospheric mantle in the
... The crystalline basement of Sardinia is made up of late Precambrian to Palaeozoic rocks, mostly metamorphosed during the Hercynian Orogeny (Carboniferous^early Permian). During this time, subduction of the proto-Tethys Ocean between the Gondwanan and Laurussian plates [5] was followed by a continent ...
... The crystalline basement of Sardinia is made up of late Precambrian to Palaeozoic rocks, mostly metamorphosed during the Hercynian Orogeny (Carboniferous^early Permian). During this time, subduction of the proto-Tethys Ocean between the Gondwanan and Laurussian plates [5] was followed by a continent ...
Evolution of the Earth as an andesite planet: water, plate tectonics
... The Earth is unique in our solar system in having a buoyant, highland-forming continental crust with a differentiated, andesitic composition; thus, it can be referred to as an “andesite planet.” Andesitic magmatism is associated with convergent plate margins such as subduction zones, leading to a br ...
... The Earth is unique in our solar system in having a buoyant, highland-forming continental crust with a differentiated, andesitic composition; thus, it can be referred to as an “andesite planet.” Andesitic magmatism is associated with convergent plate margins such as subduction zones, leading to a br ...
Divergent Plate Boundaries - North Coast Distance Education
... across the South Pacific, ending in the Gulf of California, a total length of about 70,000 km. Without question, it is the greatest “mountain” system on Earth. The internal structures of the “mountains” of the oceanic ridge, however, are nothing like the mountains of the continents, which largely co ...
... across the South Pacific, ending in the Gulf of California, a total length of about 70,000 km. Without question, it is the greatest “mountain” system on Earth. The internal structures of the “mountains” of the oceanic ridge, however, are nothing like the mountains of the continents, which largely co ...
Evolution of the Earth as an andesite planet: water
... The Earth is unique in our solar system in having a buoyant, highland-forming continental crust with a differentiated, andesitic composition; thus, it can be referred to as an “andesite planet.” Andesitic magmatism is associated with convergent plate margins such as subduction zones, leading to a br ...
... The Earth is unique in our solar system in having a buoyant, highland-forming continental crust with a differentiated, andesitic composition; thus, it can be referred to as an “andesite planet.” Andesitic magmatism is associated with convergent plate margins such as subduction zones, leading to a br ...
the granulite belt of lapland and the belomorides
... Despite their metamorphic fabric they are clearly different from the rhyodacitic metavolcanics, particularly in their higher K and Rb contents (4 % and 150 ppm respectively). Although most of them are of unknown age, one occurrence near Lemmeskäpalo yielded zircon ages of 2.36 Ga (Meriläinen 1976). ...
... Despite their metamorphic fabric they are clearly different from the rhyodacitic metavolcanics, particularly in their higher K and Rb contents (4 % and 150 ppm respectively). Although most of them are of unknown age, one occurrence near Lemmeskäpalo yielded zircon ages of 2.36 Ga (Meriläinen 1976). ...
Evolution of the Atmosphere and Oceans: Evidence from Geological
... tion such as the uptake of CO 2 by microorganisms could trigger precipitation of CaC0 3. Precambrian evaporites on the other hand present evidences for curtailed sulphate precipitation. As mentioned earlier, Phanerozoic evaporites follow the crystallisa.tion path of modern seawater. On the other han ...
... tion such as the uptake of CO 2 by microorganisms could trigger precipitation of CaC0 3. Precambrian evaporites on the other hand present evidences for curtailed sulphate precipitation. As mentioned earlier, Phanerozoic evaporites follow the crystallisa.tion path of modern seawater. On the other han ...
geochronology of proterozoic basement inliers from the colombian
... Global orogenic events on the 1,2-0,98 Ga age interval (the Grenville orogenic cycle) have been attributed to successive continental collisions leading to the agglutination of the Rodinia Supercontinent (Hoffmann, 1991). Within the eastern Colombian Andes a few tectonic inliers of high grade metamor ...
... Global orogenic events on the 1,2-0,98 Ga age interval (the Grenville orogenic cycle) have been attributed to successive continental collisions leading to the agglutination of the Rodinia Supercontinent (Hoffmann, 1991). Within the eastern Colombian Andes a few tectonic inliers of high grade metamor ...
SCIENCE CHINA Magmatism during continental collision
... Orogen began at 50 Ma (An et al., 2001), which is contemporaneous with the UHP metamorphism. Up to now, the India plate is still moving northward at a speed of 3–4 cm yr−1. Therefore, for the Himalaya Orogen, the orogeny might have lasted for 65–70 Myr, but it remains further clarification whether t ...
... Orogen began at 50 Ma (An et al., 2001), which is contemporaneous with the UHP metamorphism. Up to now, the India plate is still moving northward at a speed of 3–4 cm yr−1. Therefore, for the Himalaya Orogen, the orogeny might have lasted for 65–70 Myr, but it remains further clarification whether t ...
Eds. I. S. Evans, R. Dikau, E. Tokunaga, H. Ohmori... © by TERRAPUB, Tokyo, 2003.
... ridges (MORs), while the second one—for peripheral ocean areas. Both morphostructure types co-exist within the framework of uniform ocean crust, an integral process of the ocean floor spreading. Hence, the morphostructure division into two parts is an evidence of a complex evolutionary transformatio ...
... ridges (MORs), while the second one—for peripheral ocean areas. Both morphostructure types co-exist within the framework of uniform ocean crust, an integral process of the ocean floor spreading. Hence, the morphostructure division into two parts is an evidence of a complex evolutionary transformatio ...
Supercontinent
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as P.F. Hoffman (1999) use the term ""supercontinent"" to mean ""a clustering of nearly all continents"". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.