Tectonic activity recorded by multiple episodes of zircon growth: an
... media, a suggestion supported by stable isotope evidence, but this could also relate to the intrinsic chemical properties of the calc-silicates. Mobility of zirconium in fluids is enhanced if the Zr can be transported as a fluoride complex. As such solutions are mildly acidic they may precipitate zi ...
... media, a suggestion supported by stable isotope evidence, but this could also relate to the intrinsic chemical properties of the calc-silicates. Mobility of zirconium in fluids is enhanced if the Zr can be transported as a fluoride complex. As such solutions are mildly acidic they may precipitate zi ...
Origin of carbonatites in the South Qinling orogen:
... dacite, rhyolite and pyroclastic rocks, and the Neoproterozoic Yaolinghe group made up of tholeiitic basalt, spilitic diabase, alkali trachyte and spilite (Huang, 1993). Many occurrences of carbonatites have now been identified in this part of China; these rocks were emplaced into the deformed southe ...
... dacite, rhyolite and pyroclastic rocks, and the Neoproterozoic Yaolinghe group made up of tholeiitic basalt, spilitic diabase, alkali trachyte and spilite (Huang, 1993). Many occurrences of carbonatites have now been identified in this part of China; these rocks were emplaced into the deformed southe ...
NORSK GEOLOGISK TIDSSKRIFT 45 DISTRIBUTION PATTERNS
... The alternative is to use the method of CoRYELL et al. (1963) (see p. 252), and relate all other results to one base analysis. The most desirable distribution to use as a base would be the initial distribution in the earth. ScHMITT et al. (1963, 1964) have assumed that this was dose to, if not ident ...
... The alternative is to use the method of CoRYELL et al. (1963) (see p. 252), and relate all other results to one base analysis. The most desirable distribution to use as a base would be the initial distribution in the earth. ScHMITT et al. (1963, 1964) have assumed that this was dose to, if not ident ...
Eds. I. S. Evans, R. Dikau, E. Tokunaga, H. Ohmori... © by TERRAPUB, Tokyo, 2003.
... lava plateaus and plains, which is not directly related to present-day MORs. Riftgeneous morphostructure is typical of MORs, while the volcanic-block one is ...
... lava plateaus and plains, which is not directly related to present-day MORs. Riftgeneous morphostructure is typical of MORs, while the volcanic-block one is ...
Geotourism in the Oman Mountains Prof. Dr. Sobhi Nasir
... its original position – at bottom of the sea - onto Oman around 90 million years ago. The Oman Ophiolite outcrops in a belt 600 km long and 150 km wide and between 5 and 10 km thick. It provides us with a peak beneath the seafloor and exposes one of the most hidden boundaries (Moho) of planet Earth. ...
... its original position – at bottom of the sea - onto Oman around 90 million years ago. The Oman Ophiolite outcrops in a belt 600 km long and 150 km wide and between 5 and 10 km thick. It provides us with a peak beneath the seafloor and exposes one of the most hidden boundaries (Moho) of planet Earth. ...
Iceland is cool: An origin for the Iceland volcanic province in the
... locus of spreading in Iceland, thought to be consistent with an eastward-migrating plume, and a maximum in crustal thickness and volcanic activity beneath central Iceland. The features quoted are, however, required by the complex tectonic history of the region, which is described in this section. Fo ...
... locus of spreading in Iceland, thought to be consistent with an eastward-migrating plume, and a maximum in crustal thickness and volcanic activity beneath central Iceland. The features quoted are, however, required by the complex tectonic history of the region, which is described in this section. Fo ...
Physics and chemistry of the Earth`s interior – Oceanic
... Defined seismically: the step in velocity from ~7.5 to 8.1 km/s and believed to be the transition downward into ultramafic rock …the seismic Moho The petrological Moho: the divide between residual mantle ultramafics and material derived from melt (including cumulate ...
... Defined seismically: the step in velocity from ~7.5 to 8.1 km/s and believed to be the transition downward into ultramafic rock …the seismic Moho The petrological Moho: the divide between residual mantle ultramafics and material derived from melt (including cumulate ...
EOCENE TECTONIC EVOLUTION OF NW MEXICO (SONORA and
... and Sonora, that is, actually, between two parts of the Baja-Borderland terrane, or block.] Gastil (1991) assumed that the terrane (block) in question could have travelled north along a California-Oaxaca megashear.with a convexity towards the West (implying, possibly, an accordance with the subducti ...
... and Sonora, that is, actually, between two parts of the Baja-Borderland terrane, or block.] Gastil (1991) assumed that the terrane (block) in question could have travelled north along a California-Oaxaca megashear.with a convexity towards the West (implying, possibly, an accordance with the subducti ...
Geochemical evidence for interaction between oceanic crust and
... eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary basins in eastern China suggests that Cenozoic basaltic magmatism was probably associated with extension and thinning of the lithosphere along the eastern edge of the Eurasian continent (Ma and Wu, 19 ...
... eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary basins in eastern China suggests that Cenozoic basaltic magmatism was probably associated with extension and thinning of the lithosphere along the eastern edge of the Eurasian continent (Ma and Wu, 19 ...
Understanding the 3D Structure of the Gilmore Fault Zone Through
... locus of orogenesis, generally young from west to east. The WMB dominates the central zone and the eastern zone is characterised by a series of Silurian-to Devonian rift basins (e.g., the Tumut Trough, which is adjacent to the GFZ) and granite batholiths developed on a Cambro-Ordovician basement. Th ...
... locus of orogenesis, generally young from west to east. The WMB dominates the central zone and the eastern zone is characterised by a series of Silurian-to Devonian rift basins (e.g., the Tumut Trough, which is adjacent to the GFZ) and granite batholiths developed on a Cambro-Ordovician basement. Th ...
TROPICS Continent-Building in Costa Rica
... is to produce new continental crust through subduction-related magmatism. However, the bulk crustal composition inferred for most intra-oceanic arcs is basaltic and does not match either the geophysical structure or the composition of continental crust. To solve this conundrum, a two-step procedure ...
... is to produce new continental crust through subduction-related magmatism. However, the bulk crustal composition inferred for most intra-oceanic arcs is basaltic and does not match either the geophysical structure or the composition of continental crust. To solve this conundrum, a two-step procedure ...
Rhenium–osmium isotope and elemental behaviour during
... the original sample composition fell either within the MORB field (for basalts) or within the field defined by the measured unaltered gabbros (for gabbroic lithologies). Thus, it can be estimated that the circled sample (Fig. 3a) may have lost approximately 80% of its initial Ba. Both Rb and K (not ...
... the original sample composition fell either within the MORB field (for basalts) or within the field defined by the measured unaltered gabbros (for gabbroic lithologies). Thus, it can be estimated that the circled sample (Fig. 3a) may have lost approximately 80% of its initial Ba. Both Rb and K (not ...
Indentation of a continent with a built
... transfer before suturing is thought to be reversed after suturing. Instead of weak wet sediments being transferred from the subducting plate onto the non-subducting plate, continental suturing is thought to be followed by the transfer of weak warm upper crust onto cold stiff continent. The transfer ...
... transfer before suturing is thought to be reversed after suturing. Instead of weak wet sediments being transferred from the subducting plate onto the non-subducting plate, continental suturing is thought to be followed by the transfer of weak warm upper crust onto cold stiff continent. The transfer ...
Structure of the Lithosphere and the Sedimentary Record: Where do
... followed by an unconformity and rapid uplift after several million years. This is consistent with a model in which rapid sedimentation generates a negative thermal anomaly which temporarily offsets the positive, crustal, thermal anomaly generated by the impact event. Imaging the structure of crust b ...
... followed by an unconformity and rapid uplift after several million years. This is consistent with a model in which rapid sedimentation generates a negative thermal anomaly which temporarily offsets the positive, crustal, thermal anomaly generated by the impact event. Imaging the structure of crust b ...
Weakness of the lower continental crust: a condition for
... We discuss three interconnected processes that occur during continental compression and extension: delamination of the lower crust and sub-crustal lithosphere, escape tectonics (i.e., lateral crustal flow), and crustal uplift. We combine calculations of lithospheric viscosity–depth curves with geolo ...
... We discuss three interconnected processes that occur during continental compression and extension: delamination of the lower crust and sub-crustal lithosphere, escape tectonics (i.e., lateral crustal flow), and crustal uplift. We combine calculations of lithospheric viscosity–depth curves with geolo ...
Setting Based Classification
... • Caused by hot H2O-rich fluids and usually involving metasomatism Coombs (1961) • Difficult type of metamorphism to constrain, since hydrothermal effects often play some role in most of the other types of metamorphism ...
... • Caused by hot H2O-rich fluids and usually involving metasomatism Coombs (1961) • Difficult type of metamorphism to constrain, since hydrothermal effects often play some role in most of the other types of metamorphism ...
Structural control on present-day topography of a basement massif
... rocks of the Sirwa (see Fig. 3 B). B) The Anti-Atlas Major Fault South of the Sirwa region. Neogene sedimentary and volcanic rocks have a vertical offset of 500m related to the reverse slip of the fault. In the uplifted hanging wall, the High Erosional Surface is preserved beneath Neogene rocks. C) ...
... rocks of the Sirwa (see Fig. 3 B). B) The Anti-Atlas Major Fault South of the Sirwa region. Neogene sedimentary and volcanic rocks have a vertical offset of 500m related to the reverse slip of the fault. In the uplifted hanging wall, the High Erosional Surface is preserved beneath Neogene rocks. C) ...
Zuni–Bandera volcanism, Rio Grande, USA — Melt formation in
... the active Rio Grande Rift. Alkalic and tholeiitic magmas have erupted through Proterozoic continental crust with the tholeiitic magmas having undergone shallow-level fractional crystallization of olivine ± clinopyroxene ± spinel. The alkaline–tholeiitic lava flows lack elemental and isotopic correl ...
... the active Rio Grande Rift. Alkalic and tholeiitic magmas have erupted through Proterozoic continental crust with the tholeiitic magmas having undergone shallow-level fractional crystallization of olivine ± clinopyroxene ± spinel. The alkaline–tholeiitic lava flows lack elemental and isotopic correl ...
Rheological heterogeneity, mechanical anisotropy
... This paper aims to present an overview on the influence of rheological heterogeneity and mechanical anisotropy on the deformation of continents. After briefly recapping the concept of rheological stratification of the lithosphere, we discuss two specific issues: (1) as supported by a growing body of ...
... This paper aims to present an overview on the influence of rheological heterogeneity and mechanical anisotropy on the deformation of continents. After briefly recapping the concept of rheological stratification of the lithosphere, we discuss two specific issues: (1) as supported by a growing body of ...
Late-orogenic heating during exhumation: Alpine PTt trajectories
... upper crustal radiogenic material in the crustal and/or mantle wedge directly overlying the subducting lithosphere. This wedge is referred to as Tectonically Accreted Radiogenic Material (TARM). A key result of this study is that some of the rocks moving through the wedge undergo heating during the ...
... upper crustal radiogenic material in the crustal and/or mantle wedge directly overlying the subducting lithosphere. This wedge is referred to as Tectonically Accreted Radiogenic Material (TARM). A key result of this study is that some of the rocks moving through the wedge undergo heating during the ...
The Imbert Formation of northern Hispaniola: a tectono
... Chaotic rock assemblages, often referred in a descriptive non-genetic sense as a mélange (Cowan, 1985), are commonly found in forearc and trench environments and are attributed either to tectonic, sedimentary or diapiric processes, as well as their mutual interplay and superposition (Harris et al., ...
... Chaotic rock assemblages, often referred in a descriptive non-genetic sense as a mélange (Cowan, 1985), are commonly found in forearc and trench environments and are attributed either to tectonic, sedimentary or diapiric processes, as well as their mutual interplay and superposition (Harris et al., ...
What is A Volcano?
... The most devastating destruction from volcanoes is the tremendous loss of life. Following an eruption in 1815, there were 56 000 people killed by a tidal wave from a eruption. Lava from the volcano is hot enough to catch everything in its path on fire, even the ash from a volcano is hot enough to st ...
... The most devastating destruction from volcanoes is the tremendous loss of life. Following an eruption in 1815, there were 56 000 people killed by a tidal wave from a eruption. Lava from the volcano is hot enough to catch everything in its path on fire, even the ash from a volcano is hot enough to st ...
nature ano evolution of the subcontinental mantle lithosphere below
... The Sr and Nd isotopic compositions of the inelusions are similar to oceanic basalts, with the isotopic compositions of the fertile garnet-Iherzolites being similar to MORB. The lack of any phases with Sr and Nd isotopic compositions implying ancient enrichment event, such as have been reported from ...
... The Sr and Nd isotopic compositions of the inelusions are similar to oceanic basalts, with the isotopic compositions of the fertile garnet-Iherzolites being similar to MORB. The lack of any phases with Sr and Nd isotopic compositions implying ancient enrichment event, such as have been reported from ...
The Geology of the Paleozoic Era
... • Global tectonic theme of the Paleozoic assembly of the supercontinent, Pangaea. • Deposition due to transgressions (and disconformities due regressions) of shallow continental (epeiric) seas. Interiors of continents were frequently flooded. • Formation of mountain belts at edges – tectonic activit ...
... • Global tectonic theme of the Paleozoic assembly of the supercontinent, Pangaea. • Deposition due to transgressions (and disconformities due regressions) of shallow continental (epeiric) seas. Interiors of continents were frequently flooded. • Formation of mountain belts at edges – tectonic activit ...
3 Factors controlling the crustal density structure - diss.fu
... heterogeneous, having a wide range of chemical compositions and a complex tectonic structure. The inaccessibility of the lower crust masks its nature and, therefore, knowledge of its compositional structure is mainly derived from models based on indirect observables like seismic velocities and surfa ...
... heterogeneous, having a wide range of chemical compositions and a complex tectonic structure. The inaccessibility of the lower crust masks its nature and, therefore, knowledge of its compositional structure is mainly derived from models based on indirect observables like seismic velocities and surfa ...
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.