Evolutionary cycles during the Andean orogeny
... rebound of the slab tip (owing to lack of further slab pull), flat subduction and termination of subduction-related magmatism. Rapid subduction leads to shallow overriding of the detached slab fragment. Eclogitization of the gradually steepening slab tip at depth and subsequent slab pull permits ast ...
... rebound of the slab tip (owing to lack of further slab pull), flat subduction and termination of subduction-related magmatism. Rapid subduction leads to shallow overriding of the detached slab fragment. Eclogitization of the gradually steepening slab tip at depth and subsequent slab pull permits ast ...
Stratigraphy, geochemistry and tectonic significance of the
... In western Oaxaca, Tertiary magmatic activity is represented by extensive plutons along the continental margin and volcanic sequences in the inland region. K–Ar age determinations reported previously and in the present work indicate that these rocks correspond to a relatively broad arc in this regio ...
... In western Oaxaca, Tertiary magmatic activity is represented by extensive plutons along the continental margin and volcanic sequences in the inland region. K–Ar age determinations reported previously and in the present work indicate that these rocks correspond to a relatively broad arc in this regio ...
Cratonic keels and a 2-layer mantle tested:
... Russia-Arabia cratons HAS driven the keel of Moesia westwards, and is still active (Vrancea). 2. In the Oligocene this action drove the Balkans ~200km westward. This built the Western Alps and started Apennines construction by reactivating Cretaceous subduction and triggering Tyrrhenian slab pull. 3 ...
... Russia-Arabia cratons HAS driven the keel of Moesia westwards, and is still active (Vrancea). 2. In the Oligocene this action drove the Balkans ~200km westward. This built the Western Alps and started Apennines construction by reactivating Cretaceous subduction and triggering Tyrrhenian slab pull. 3 ...
Paleomagnetic reconstruction of Coahuila, Mexico
... of folded upper Mesozoic sedimentary rocks that overlie a Precambrian and Paleozoic basement (López et al., 2001). Coahuila island (Figure 1, inset) is a Cretaceous paleogeographic element of northern Mexico that has been interpreted as a block of continental crust accreted to the North America cont ...
... of folded upper Mesozoic sedimentary rocks that overlie a Precambrian and Paleozoic basement (López et al., 2001). Coahuila island (Figure 1, inset) is a Cretaceous paleogeographic element of northern Mexico that has been interpreted as a block of continental crust accreted to the North America cont ...
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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 ...
Recognizing optimum Banded-Iron Formation
... BIF–hosted gold deposits in the Churchill Province are genetically related and structurally controlled by Paleoproterozoic (1.83 Ga) tectonometamorphic events superimposed on Archean rocks. BIF–hosted gold deposits commonly form large isolated entities without an associated district. The first-order ...
... BIF–hosted gold deposits in the Churchill Province are genetically related and structurally controlled by Paleoproterozoic (1.83 Ga) tectonometamorphic events superimposed on Archean rocks. BIF–hosted gold deposits commonly form large isolated entities without an associated district. The first-order ...
(Nyasa) Rift US Scientists Donna J. Shillingt
... evolution of early-stage rifts. Key questions concern the origin and role of magma during earliest rifting, the formation and evolution of rift segmentation and its manifestation at depth in the crust and lithosphere, and the temporal style of deformation (episodic versus steady-state). The SEGMeNT ...
... evolution of early-stage rifts. Key questions concern the origin and role of magma during earliest rifting, the formation and evolution of rift segmentation and its manifestation at depth in the crust and lithosphere, and the temporal style of deformation (episodic versus steady-state). The SEGMeNT ...
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... Cr data are normalized to NBS 52Cr/ 50Cr=19.28323 [54]. All uncertainties are 2r. Data after ...
... Cr data are normalized to NBS 52Cr/ 50Cr=19.28323 [54]. All uncertainties are 2r. Data after ...
Origins of the lower crustal reflectivity in the L¨utzow
... by assuming a layered lower crustal model with velocity changes of 0.3 km/s in shear waves for 0.5–1.0 km thick layers. The origin of lower crustal reflectivity is discussed in terms of high-pressure laboratory measurements on metamorphic rocks from Western Enderby Land. Lower crustal velocities of ...
... by assuming a layered lower crustal model with velocity changes of 0.3 km/s in shear waves for 0.5–1.0 km thick layers. The origin of lower crustal reflectivity is discussed in terms of high-pressure laboratory measurements on metamorphic rocks from Western Enderby Land. Lower crustal velocities of ...
Precambrian stratigraphy of Manzanita and north Manzano
... financial support for the field work. ...
... financial support for the field work. ...
Continental Growth and Recycling in Convergent Orogens with
... granitic rocks are uncommon and tend to be post-orogenic [43]. Sr and Nd isotopic data (87Sr/86Sr 0.704 to 0.720; εNd +4 to −11 [44,45]) define a hyperbolic mixing array. I-type granites generally give lower 87Sr/86Sr and higher εNd than S-types, which trend towards the more evolved compositions of ...
... granitic rocks are uncommon and tend to be post-orogenic [43]. Sr and Nd isotopic data (87Sr/86Sr 0.704 to 0.720; εNd +4 to −11 [44,45]) define a hyperbolic mixing array. I-type granites generally give lower 87Sr/86Sr and higher εNd than S-types, which trend towards the more evolved compositions of ...
A unique lower mantle source for Southern Italy volcanics
... The Southern Italy volcanism is characterized by the unusual occurrence of volcanic rocks with ocean-island basalt (OIB)-like characteristics, in particular at Etna and Iblean Mts in Sicily. The geochemical properties of the source of the Italian magmatism are usually explained by a north–south bina ...
... The Southern Italy volcanism is characterized by the unusual occurrence of volcanic rocks with ocean-island basalt (OIB)-like characteristics, in particular at Etna and Iblean Mts in Sicily. The geochemical properties of the source of the Italian magmatism are usually explained by a north–south bina ...
AM N Pz Scale 1:8 500 000 - Norges geologiske undersøkelse
... (Based on Boyd. R. in: Eilu et al., 2012) Bog iron ores were exploited in Norway as early as 400 BC: 14C dating shows that twenty-eight deposits had been exploited in central Norway alone prior to 200 AD (Stenvik, 2005). The oldest record of underground mining (late 12th C) is from the Akersberg sil ...
... (Based on Boyd. R. in: Eilu et al., 2012) Bog iron ores were exploited in Norway as early as 400 BC: 14C dating shows that twenty-eight deposits had been exploited in central Norway alone prior to 200 AD (Stenvik, 2005). The oldest record of underground mining (late 12th C) is from the Akersberg sil ...
Deforming Earth*s Crust
... • Faults are never straight up and down, they are on an angle and have their own names. ...
... • Faults are never straight up and down, they are on an angle and have their own names. ...
Crust-Mantle Connections in the Kermadec Arc
... E-mail: tamuray@jamstec.go.jp A new study presents the straightforward but unexpected relationship, which relates crustal thickness to magma type in the Izu-Ogasawara (Bonin) and Aleutian oceanic arcs (Tamura et al., 2016). Volcanoes along the southern segment of the Izu-Ogasawara arc and the wester ...
... E-mail: tamuray@jamstec.go.jp A new study presents the straightforward but unexpected relationship, which relates crustal thickness to magma type in the Izu-Ogasawara (Bonin) and Aleutian oceanic arcs (Tamura et al., 2016). Volcanoes along the southern segment of the Izu-Ogasawara arc and the wester ...
Hot and cold granites? Implications of zircon
... the lithosphere. Heating by influx of mafic magma is permitted but may not be required. In contrast, generation of hot granites is likely to require an important influx of heat but not fluid; heating is most simply explained by intrusion of mafic magma. Although the timing relative to thrusting is n ...
... the lithosphere. Heating by influx of mafic magma is permitted but may not be required. In contrast, generation of hot granites is likely to require an important influx of heat but not fluid; heating is most simply explained by intrusion of mafic magma. Although the timing relative to thrusting is n ...
hall_church_comments
... representative of their thickness at the time of crust formation. Allerton and Vine furthered argued that the Solea Graben was formed by off-axis extension during lulls in the supply of magma to an intermediate to fast-spreading axis, in which case the relationship between ores and magma supply beco ...
... representative of their thickness at the time of crust formation. Allerton and Vine furthered argued that the Solea Graben was formed by off-axis extension during lulls in the supply of magma to an intermediate to fast-spreading axis, in which case the relationship between ores and magma supply beco ...
Incremental Emplacement of Nelson Batholith
... 1988). Carr and Simony (2006) hypothesized based on this data that the BMT suite was linked at depth by former magma conduits and based largely on field-mapping and structural analysis, they surmise that the deep portions of the NB and BMT suite was sheared and thrusted during the Cretaceous–Paleoce ...
... 1988). Carr and Simony (2006) hypothesized based on this data that the BMT suite was linked at depth by former magma conduits and based largely on field-mapping and structural analysis, they surmise that the deep portions of the NB and BMT suite was sheared and thrusted during the Cretaceous–Paleoce ...
- NERC Open Research Archive
... Avalonia collided with the Laurentian margin in the Early Devonian (between 419 Ma and 400Ma). Interestingly, no tectonic event has been detected in the coherent Devonian marine successions in Devon or in the Belgium Ardennes at this time. However, Woodcock et al. (2007) pointed out that Iapetus Oce ...
... Avalonia collided with the Laurentian margin in the Early Devonian (between 419 Ma and 400Ma). Interestingly, no tectonic event has been detected in the coherent Devonian marine successions in Devon or in the Belgium Ardennes at this time. However, Woodcock et al. (2007) pointed out that Iapetus Oce ...
Geology of granite - Royal Society of Western Australia
... form narrow, linear belts, generally 50 - 100 km wide and thousands of kilometres long. These belts occur within, and parallel to, the margins of continents. The Andes (Fig 12) provides one of the simplest examples. Here, in a head-on collision, the South American continent is being pushed over Paci ...
... form narrow, linear belts, generally 50 - 100 km wide and thousands of kilometres long. These belts occur within, and parallel to, the margins of continents. The Andes (Fig 12) provides one of the simplest examples. Here, in a head-on collision, the South American continent is being pushed over Paci ...
Physical Processes Along Internal Boundaries In An Con
... entirely coupled with Barrandian host rocks (NE-SW striking steep foliation and sub-horizontal NE-SW trending lineation determined by mean of AMS, mostly oblate to plane strain fabrics). Mechanisms which may have accommodated pluton emplacement during transpression involve multiple material transfer ...
... entirely coupled with Barrandian host rocks (NE-SW striking steep foliation and sub-horizontal NE-SW trending lineation determined by mean of AMS, mostly oblate to plane strain fabrics). Mechanisms which may have accommodated pluton emplacement during transpression involve multiple material transfer ...
- Canada-Nunavut Geoscience Office
... and sampling, as well as regional and focused thematic studies. Data and information collected during this project will be used to 1) produce new bedrock and surficial geological maps (1:100 000 Canada Geoscience Maps) for all or parts of eight National Topographic System (NTS) map areas (46E, D, 56 ...
... and sampling, as well as regional and focused thematic studies. Data and information collected during this project will be used to 1) produce new bedrock and surficial geological maps (1:100 000 Canada Geoscience Maps) for all or parts of eight National Topographic System (NTS) map areas (46E, D, 56 ...
1 Accretion of terranes and growth of continental crust along the
... result of tectonic loading on the southern margin of Laurentian continental crust. Deformed synorogenic deposits are overlain by an undeformed Upper Pennsylvanian– Middle Permian shallow-marine fill of a successor basin, indicating the termination of orogenic contraction and terrane accretion within ...
... result of tectonic loading on the southern margin of Laurentian continental crust. Deformed synorogenic deposits are overlain by an undeformed Upper Pennsylvanian– Middle Permian shallow-marine fill of a successor basin, indicating the termination of orogenic contraction and terrane accretion within ...
Sedimentary Basins related to Volcanic Arcs
... volcanic arc and submarine trench • range from small basins on trench slope to large basins (50 to 100 km wide, and > 500 km long) with thick fills (several km) • Basins tend to become wider and shallower with time, partly because of accretion at trenches ...
... volcanic arc and submarine trench • range from small basins on trench slope to large basins (50 to 100 km wide, and > 500 km long) with thick fills (several km) • Basins tend to become wider and shallower with time, partly because of accretion at trenches ...
Baltic Shield
The Baltic Shield (sometimes referred to as the Fennoscandian Shield) is located in Fennoscandia (Norway, Sweden and Finland), northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton. It is composed mostly of Archean and Proterozoic gneisses and greenstones which have undergone numerous deformations through tectonic activity (see Geology of Fennoscandia map [1]). The Baltic Shield contains the oldest rocks of the European continent. The lithospheric thickness is about 200-300 km. During the Pleistocene epoch, great continental ice sheets scoured and depressed the shield's surface, leaving a thin covering of glacial material and innumerable lakes and streams. The Baltic Shield is still rebounding today following the melting of the thick glaciers during the Quaternary Period.