Lewisian, Torridonian and Moine Rocks of Scotland
... northern Scotland, including Archaean to Palaeoproterozoic basement (the Lewisian Gneiss Complex) and later Proterozoic sedimentary and metasedimentary rocks (the Torridonian and Moine successions). The volume also contains detailed descriptions of structures within the Moine Thrust Belt and the nor ...
... northern Scotland, including Archaean to Palaeoproterozoic basement (the Lewisian Gneiss Complex) and later Proterozoic sedimentary and metasedimentary rocks (the Torridonian and Moine successions). The volume also contains detailed descriptions of structures within the Moine Thrust Belt and the nor ...
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... rocks may be the result of the remelting of pre-existing continental crust, in which case the crust is referred to as “reworked,” “rejuvenated” or “remelted.” Juvenile versus reworked crust can also be distinguished by whether isotopic compositions are relatively homogeneous and mantle-like (in the ...
... rocks may be the result of the remelting of pre-existing continental crust, in which case the crust is referred to as “reworked,” “rejuvenated” or “remelted.” Juvenile versus reworked crust can also be distinguished by whether isotopic compositions are relatively homogeneous and mantle-like (in the ...
The Architecture, Chemistry, and Evolution of Continental Magmatic
... such is the case with the belt of arc-related magmatism that formed during the Laramide orogeny (75–35 Ma) in the interior of the North American Cordillera due to shallow subduction (Barton 1996). This extensive belt of plutons that makes up the Cordilleran interior arc is well exposed in Arizona, N ...
... such is the case with the belt of arc-related magmatism that formed during the Laramide orogeny (75–35 Ma) in the interior of the North American Cordillera due to shallow subduction (Barton 1996). This extensive belt of plutons that makes up the Cordilleran interior arc is well exposed in Arizona, N ...
Origin of carbonatites in the South Qinling orogen:
... show a Sr–Nd isotopic signature similar to that of the chondritic uniform reservoir (CHUR), and parallel Sm–Nd model ages (TCHUR) of 190–300 Ma. However, the rocks have extremely variable Pb isotopic values straddling between the HIMU and EM1 mantle end-members. Most carbon and oxygen isotopic compo ...
... show a Sr–Nd isotopic signature similar to that of the chondritic uniform reservoir (CHUR), and parallel Sm–Nd model ages (TCHUR) of 190–300 Ma. However, the rocks have extremely variable Pb isotopic values straddling between the HIMU and EM1 mantle end-members. Most carbon and oxygen isotopic compo ...
Differential preservation in the geologic record of intraoceanic arc
... Intraoceanic subduction zones undergoing tectonic erosion exhibit important differences from those in a state of tectonic accretion (Fig. 2). Approximately one quarter of modern oceanic arcs experience long-term accretion from the downgoing plate (Fig. 2A), whereas three quarters are of the erosiona ...
... Intraoceanic subduction zones undergoing tectonic erosion exhibit important differences from those in a state of tectonic accretion (Fig. 2). Approximately one quarter of modern oceanic arcs experience long-term accretion from the downgoing plate (Fig. 2A), whereas three quarters are of the erosiona ...
Differentiation of the continental crust by relamination
... recorded in some arc sections (DeBari and Sleep, 1991; Kelemen et al., 2003a), loss of these rocks still yielded a mafic arc crust very different from continental crust (DeBari and Sleep, 1991; Greene et al., 2006). This is so because garnet-free mafic rocks that are either density-stable or too visco ...
... recorded in some arc sections (DeBari and Sleep, 1991; Kelemen et al., 2003a), loss of these rocks still yielded a mafic arc crust very different from continental crust (DeBari and Sleep, 1991; Greene et al., 2006). This is so because garnet-free mafic rocks that are either density-stable or too visco ...
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... assembly and accretion to the Saharan Metacraton concurrent with the assembly of eastern and western Gondwana. At the end of the Precambrian it lay at one end of the East African Orogen, with its northern margin (present coordinates) forming a low-relief stable shelf facing an open ocean; to the sou ...
... assembly and accretion to the Saharan Metacraton concurrent with the assembly of eastern and western Gondwana. At the end of the Precambrian it lay at one end of the East African Orogen, with its northern margin (present coordinates) forming a low-relief stable shelf facing an open ocean; to the sou ...
34 - School of Ocean and Earth Science and Technology
... are themselves surrounded by Proterozoic rock. This pattern suggests the continents grew over time around the Early Archean “nuclei.” Large areas of the continents are >1 Ga, so by about 1 Ga much of the crust had been formed. ...
... are themselves surrounded by Proterozoic rock. This pattern suggests the continents grew over time around the Early Archean “nuclei.” Large areas of the continents are >1 Ga, so by about 1 Ga much of the crust had been formed. ...
Peridotite and Metabasic Rocks of the Marianské Lázně
... The MLC consists predominantly of metabasic rocks, including eclogite, metagabbro, and various amphibolites, and subordinate amounts of serpentinite, feldspathic gneiss (metakeratophyre), and calcsilicate rocks. In this excursion, five localities have been selected to illustrate four of the important ...
... The MLC consists predominantly of metabasic rocks, including eclogite, metagabbro, and various amphibolites, and subordinate amounts of serpentinite, feldspathic gneiss (metakeratophyre), and calcsilicate rocks. In this excursion, five localities have been selected to illustrate four of the important ...
The detrital record of orogenesis: A review of approaches and
... Sediments eroded from the mountain belt have been deposited in the marine depositional environments of remnant ocean basins and deep sea fans, and in sedimentary basins on land of which the major depocentres are the foreland basin and suture zone (Fig. 3). ...
... Sediments eroded from the mountain belt have been deposited in the marine depositional environments of remnant ocean basins and deep sea fans, and in sedimentary basins on land of which the major depocentres are the foreland basin and suture zone (Fig. 3). ...
res terrae - Oulun yliopisto
... caused a fluctuating base level, which created an accommodating space for basin-fills during the pure extensional tectonics. The lack of a deepwater sedimentation prism and oceanic crust, and the non-evolution to passive margin indicate that the rifting failed to complete the continental break-up. A ...
... caused a fluctuating base level, which created an accommodating space for basin-fills during the pure extensional tectonics. The lack of a deepwater sedimentation prism and oceanic crust, and the non-evolution to passive margin indicate that the rifting failed to complete the continental break-up. A ...
full text - NWT Protected Area Strategy
... Territories. The site is recognized as a unique window into Earth’s early history as rocks at this locality have yielded ages of greater than 4 billion years old. The Acasta gneisses are a finite resource with significant scientific and cultural value. For this reason, the area is being considered f ...
... Territories. The site is recognized as a unique window into Earth’s early history as rocks at this locality have yielded ages of greater than 4 billion years old. The Acasta gneisses are a finite resource with significant scientific and cultural value. For this reason, the area is being considered f ...
the basic mineralogic, paragenetic and genetic
... In the deposits Anayatak, (Çakmakkaya and Akköy the latter forms of pyrite are very common, but they were also observed in many other deposits of this type. Enclosure of minute dense grains of some metallic minerals in others or in the host rock is a very common feature in some deposits. Massive inc ...
... In the deposits Anayatak, (Çakmakkaya and Akköy the latter forms of pyrite are very common, but they were also observed in many other deposits of this type. Enclosure of minute dense grains of some metallic minerals in others or in the host rock is a very common feature in some deposits. Massive inc ...
Sabzevar Ophiolite, NE Iran - The University of Texas at Dallas
... ophiolites, like the Nain–Baft ophiolites, to be related to a seaway surrounding the Lut Block. Shojaat et al. (2003) suggested that the Sabzevar ophiolite was emplaced during NE-dipping subduction and Noghreyan (1982) proposed formation in a back-arc basin, based on the geochemistry of lavas and ga ...
... ophiolites, like the Nain–Baft ophiolites, to be related to a seaway surrounding the Lut Block. Shojaat et al. (2003) suggested that the Sabzevar ophiolite was emplaced during NE-dipping subduction and Noghreyan (1982) proposed formation in a back-arc basin, based on the geochemistry of lavas and ga ...
alleghanian plutonism in the eastern blue ridge
... with Laurentia (Massey and Moecher 2005). East-dipping thrusts do not rule out an arc setting for the eastern Blue Ridge (EBR) plutons because they pre-date the estimated collision. ...
... with Laurentia (Massey and Moecher 2005). East-dipping thrusts do not rule out an arc setting for the eastern Blue Ridge (EBR) plutons because they pre-date the estimated collision. ...
STATE GEOLOGICAL MAP OF UKRAINE
... m height). This part of the area is of medium-mountain type, extensively eroded, with narrow ridges, steep (2540o) slopes, narrow river and stream valleys, and altitudes 400-800 to 1000 m. Mountain slopes are overgrown with beech forests, and at the watersheds Alpine meadows (polonyny) are developed ...
... m height). This part of the area is of medium-mountain type, extensively eroded, with narrow ridges, steep (2540o) slopes, narrow river and stream valleys, and altitudes 400-800 to 1000 m. Mountain slopes are overgrown with beech forests, and at the watersheds Alpine meadows (polonyny) are developed ...
Early Paleozoic Tectonic and Thermomechanical
... southward oceanic subduction. The process produced a wide mélange belt and the Qilian magmatic arc. Arc magmatism was active between 520 and 400 Ma, coeval with North Qaidam UHP metamorphism. The North Qaidam UHP metamorphic belt also spatially overlaps the early Paleozoic Qilian magmatic arc. Petro ...
... southward oceanic subduction. The process produced a wide mélange belt and the Qilian magmatic arc. Arc magmatism was active between 520 and 400 Ma, coeval with North Qaidam UHP metamorphism. The North Qaidam UHP metamorphic belt also spatially overlaps the early Paleozoic Qilian magmatic arc. Petro ...
GSA TODAY - Geological Society of America
... of the resulting seafloor to the continental margin (as Sierran subduction drew it ever closer), until the ophiolite docked against the continental margin prior to the onset of Franciscan accretion; (3) Saleeby infers “forearc” seafloor spreading induced by transtensional deformation within the west ...
... of the resulting seafloor to the continental margin (as Sierran subduction drew it ever closer), until the ophiolite docked against the continental margin prior to the onset of Franciscan accretion; (3) Saleeby infers “forearc” seafloor spreading induced by transtensional deformation within the west ...
volcanogenic massive sulphide deposits
... base metal classification used by Franklin et al. (1981) and refined by Large (1992) is perhaps the most common. VMS deposits are divided into Cu-Zn, Zn-Cu and Zn-Pb-Cu groups according to their contained ratios of these three metals (Fig 2). The Cu-Zn and Zn-Cu categories for Canadian deposits were ...
... base metal classification used by Franklin et al. (1981) and refined by Large (1992) is perhaps the most common. VMS deposits are divided into Cu-Zn, Zn-Cu and Zn-Pb-Cu groups according to their contained ratios of these three metals (Fig 2). The Cu-Zn and Zn-Cu categories for Canadian deposits were ...
Guidebook
... The Crystalline-Mesozoic Zone is built up of basement shearing nappes, each of them showing large developed metamorphic formations covered by a Mesozoic or Permo-Mesozoic sedimentary envelope. The nappes, of Meso-Cretaceous age, cover each other. They are (up/down) the Bucovinian Nappe, the Subbucov ...
... The Crystalline-Mesozoic Zone is built up of basement shearing nappes, each of them showing large developed metamorphic formations covered by a Mesozoic or Permo-Mesozoic sedimentary envelope. The nappes, of Meso-Cretaceous age, cover each other. They are (up/down) the Bucovinian Nappe, the Subbucov ...
Fig. 1
... the conjugate passive continental margins. Study of passive margin geology, combined with wide-angle seismic imaging of crustal structures and rift stratigraphy provided a primary framework from which to infer the extensional mechanisms and mantle conditions that characterised breakup (e.g., White, ...
... the conjugate passive continental margins. Study of passive margin geology, combined with wide-angle seismic imaging of crustal structures and rift stratigraphy provided a primary framework from which to infer the extensional mechanisms and mantle conditions that characterised breakup (e.g., White, ...
provenance analysis and detrital zircons: keys to - ETH E
... sedimentary rocks in these accretionary complexes permits understanding the Cretaceous to Paleogene geological evolution, the geodynamic context and the tectonic-sedimentation relationships. The multidisciplinary provenance study, including sandstone framework, heavy mineral analysis, in situ U-Pb d ...
... sedimentary rocks in these accretionary complexes permits understanding the Cretaceous to Paleogene geological evolution, the geodynamic context and the tectonic-sedimentation relationships. The multidisciplinary provenance study, including sandstone framework, heavy mineral analysis, in situ U-Pb d ...
EDS011 - GeologyOntario
... settings for rocks of Mesoarchean to Cretaceous age varies widely in Ontario. The Tectonic Assemblages of Ontario map attempts to accommodate the diverse levels of confidence about our knowledge of different tectonic domains (tectonic provinces, orogens or basins) in Ontario, within a legend that i ...
... settings for rocks of Mesoarchean to Cretaceous age varies widely in Ontario. The Tectonic Assemblages of Ontario map attempts to accommodate the diverse levels of confidence about our knowledge of different tectonic domains (tectonic provinces, orogens or basins) in Ontario, within a legend that i ...
mississippi valley-type lead-zinc deposits (mvt)
... Summary of Economic Characteristics MVT deposits account for approximately 25 percent of the world's lead and zinc resources, and they are dispersed throughout the world (Fig. 1). A large proportion of Pb and Zn production comes from several classic MVT districts located in the drainage basin of the ...
... Summary of Economic Characteristics MVT deposits account for approximately 25 percent of the world's lead and zinc resources, and they are dispersed throughout the world (Fig. 1). A large proportion of Pb and Zn production comes from several classic MVT districts located in the drainage basin of the ...
Continental crust generated in oceanic arcs
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s 1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s 1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
Geological history of Earth
The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.Earth was initially molten due to extreme volcanism and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as the result of a Mars-sized object with about 10% of the Earth's mass impacting the planet in a glancing blow. Some of this object's mass merged with the Earth, significantly altering its internal composition, and a portion was ejected into space. Some of the material survived to form an orbiting moon. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered from comets, produced the oceans.As the surface continually reshaped itself over hundreds of millions of years, continents formed and broke apart. They migrated across the surface, occasionally combining to form a supercontinent. Roughly 750 million years ago, the earliest-known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia, 600 to 540 million years ago, then finally Pangaea, which broke apart 180 million years ago.The present pattern of ice ages began about 40 million years ago, then intensified at the end of the Pliocene. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000–100,000 years. The last glacial period of the current ice age ended about 10,000 years ago.