Exhumation of high-pressure rocks beneath the Solund Basin
... strike-slip faults (Andersen, 1998; Cuthbert, 1991; Osmundsen & Andersen, 2001; Osmundsen et al., 1998). Following their emplacement onto the Baltica continental margin, the Caledonide thrust sheets were reworked by a major extensional event that resulted most significantly in collapse of the thrust ...
... strike-slip faults (Andersen, 1998; Cuthbert, 1991; Osmundsen & Andersen, 2001; Osmundsen et al., 1998). Following their emplacement onto the Baltica continental margin, the Caledonide thrust sheets were reworked by a major extensional event that resulted most significantly in collapse of the thrust ...
A geological model for the structure of ridge segments in slow
... both slow and fast spreadingcrust are transformfaults; they 1990]. Off-axis, the traces of these discontinuities are modernormallyoffset the ridge axis by 30 km or more (>0.5-2 m.y. ately developedbathymetricvalleys which contain a series of age offset), are orientedin the directionof relative plate ...
... both slow and fast spreadingcrust are transformfaults; they 1990]. Off-axis, the traces of these discontinuities are modernormallyoffset the ridge axis by 30 km or more (>0.5-2 m.y. ately developedbathymetricvalleys which contain a series of age offset), are orientedin the directionof relative plate ...
Tectonic controls on the distribution of large
... subduction results in the formation of an important dextral shear zone on Sumatra, the Sumatran Fault Zone. No significant porphyry systems are known in western Indonesia. The subducting oceanic plate in this region comprises cold Eocene crust, while the thin lithosphere of SE Asia is also relativel ...
... subduction results in the formation of an important dextral shear zone on Sumatra, the Sumatran Fault Zone. No significant porphyry systems are known in western Indonesia. The subducting oceanic plate in this region comprises cold Eocene crust, while the thin lithosphere of SE Asia is also relativel ...
Crustal contamination of mafic magmas: evidence from a
... 1.85 and 1.80 Ga. In the northwestern part of the province, Archean rocks of the Border and Foreland Zones of the craton comprise the basement (Allaart, 1976). Apart from 12 major alkaline igneous complexes and a succession of supracrustal lavas and sediments (Eriksfjord Formation), a large number o ...
... 1.85 and 1.80 Ga. In the northwestern part of the province, Archean rocks of the Border and Foreland Zones of the craton comprise the basement (Allaart, 1976). Apart from 12 major alkaline igneous complexes and a succession of supracrustal lavas and sediments (Eriksfjord Formation), a large number o ...
Seismic re¯ection image revealing offset of Andean subduction
... with a given layer of subducting oceanic lithosphere has therefore remained largely unresolved8. Here we report seismic re¯ection and refraction data across the central Andean subduction zone, which image the subduction boundary to a depth of 80 km. We show, by comparing the location of this boundar ...
... with a given layer of subducting oceanic lithosphere has therefore remained largely unresolved8. Here we report seismic re¯ection and refraction data across the central Andean subduction zone, which image the subduction boundary to a depth of 80 km. We show, by comparing the location of this boundar ...
93. Lee, C. - Squarespace
... 1. Introduction 1.1. The andesite problem It is well-known that Earth’s continental crust is andesitic and that andesites are predominantly found at subduction zones (Taylor and McLennan, 1985). Understanding how andesites form is thus critical for understanding why the Earth has continents. There a ...
... 1. Introduction 1.1. The andesite problem It is well-known that Earth’s continental crust is andesitic and that andesites are predominantly found at subduction zones (Taylor and McLennan, 1985). Understanding how andesites form is thus critical for understanding why the Earth has continents. There a ...
Information Circular No. 358
... ABSTRACT A number of platinum-group-element (PGE-bearing), layered, ultramafic-mafic intrusions in the Pan-Xi and Danba areas of the southwest Sichuan Province of China have been investigated. The two study areas are located, respectively, in the central and northern parts of the Kangding Axis on th ...
... ABSTRACT A number of platinum-group-element (PGE-bearing), layered, ultramafic-mafic intrusions in the Pan-Xi and Danba areas of the southwest Sichuan Province of China have been investigated. The two study areas are located, respectively, in the central and northern parts of the Kangding Axis on th ...
Chapter 11 Section 2
... Collisions between Continental and Oceanic Crust • Some mountains form when ...
... Collisions between Continental and Oceanic Crust • Some mountains form when ...
Differentiation of the continental crust by relamination
... 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 viscous to founder remain in the cold, upper and middle crust. Whereas found ...
... 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 viscous to founder remain in the cold, upper and middle crust. Whereas found ...
Structure and geological evolution of the bedrock of
... The Svecofennian migmatite belts show a complex history of formation, with various phases of anatexis/metamorphism, deformation and intrusion. In the pelitic migmatite belt, in which the Olkiluoto site is situated, four phases of ductile deformation (0 1-0 4 ) and two phases of regional highT/lowP m ...
... The Svecofennian migmatite belts show a complex history of formation, with various phases of anatexis/metamorphism, deformation and intrusion. In the pelitic migmatite belt, in which the Olkiluoto site is situated, four phases of ductile deformation (0 1-0 4 ) and two phases of regional highT/lowP m ...
Geochemistry, Mineralogy and Petrogenesis of El
... sporadically found over an area that covers a distance of 7,000 Km from Yemen in the south through Saudi Arabia, Jordan, Syria, and up to Turkey in the north (Coleman and McGuire 1988; Camp and Roobol 1992; and Pick et al. ...
... sporadically found over an area that covers a distance of 7,000 Km from Yemen in the south through Saudi Arabia, Jordan, Syria, and up to Turkey in the north (Coleman and McGuire 1988; Camp and Roobol 1992; and Pick et al. ...
structural or climatic control in granite landforms? the
... southwestern England, exposed by nival, or periglacial, processes. This is an example of convergent development with a similar form emerging as a result of the activity of different processes. Nubbins or knolls (USA) are block- and boulder-strewn hills, but their derivation from bornhardts is sugges ...
... southwestern England, exposed by nival, or periglacial, processes. This is an example of convergent development with a similar form emerging as a result of the activity of different processes. Nubbins or knolls (USA) are block- and boulder-strewn hills, but their derivation from bornhardts is sugges ...
Sum4_Flatslabs
... the subducting plate to supplement the buoyancy factor. This was not a part of his models and is therefore a possibility. 2. There may be other possibilities not discussed by van Hunen. We discussed the possibility that there may be other mechanisms, yet undetermined, ...
... the subducting plate to supplement the buoyancy factor. This was not a part of his models and is therefore a possibility. 2. There may be other possibilities not discussed by van Hunen. We discussed the possibility that there may be other mechanisms, yet undetermined, ...
Oxygen and hydrogen isotope compositions of oceanic plutonic rocks
... between extensional veins oriented perpendicular to the metamorphic foliation and intensity of deformation. The veins related to deformation are either hornblende-bearing or hornblende- and sodic plagioclase-bearing, and are the most abundant vein type in the upper 250 m of core. Similar amphibole v ...
... between extensional veins oriented perpendicular to the metamorphic foliation and intensity of deformation. The veins related to deformation are either hornblende-bearing or hornblende- and sodic plagioclase-bearing, and are the most abundant vein type in the upper 250 m of core. Similar amphibole v ...
CH9 (ppt檔9895 KB)
... Topography resulting from different resistance to erosion of rocks reveal the presence of the plunging folds. ...
... Topography resulting from different resistance to erosion of rocks reveal the presence of the plunging folds. ...
Deep Mantle Plumes and Geoscience Vision
... The Yellowstone plume first emerged at the McDermitt caldera along the Oregon-Nevada border about 16–17 m.y. ago (Fig. 10), although it may have had ancestral expressions (Geist and Richards, 1993; Opplinger et al., 1997). From this center, dikes raced southward for hundreds of kilometers, forming t ...
... The Yellowstone plume first emerged at the McDermitt caldera along the Oregon-Nevada border about 16–17 m.y. ago (Fig. 10), although it may have had ancestral expressions (Geist and Richards, 1993; Opplinger et al., 1997). From this center, dikes raced southward for hundreds of kilometers, forming t ...
Metamorphism and Metamorphic Rocks
... conditions where there was no differential stress, and are comprised of equant minerals only. These are classified mainly by the minerals present or the chemical composition of the protolith. Foliated Metamorphic Rocks ...
... conditions where there was no differential stress, and are comprised of equant minerals only. These are classified mainly by the minerals present or the chemical composition of the protolith. Foliated Metamorphic Rocks ...
Precambrian Rocks of Alaska
... sets a minimum age of Late Ordovician for the quartzite. Thus, little doubt remains that the Neruokpuk Quartzite and underlying strata are Precambrian, but a more definite age assignment is not yet possible. Mineral resources.-Although the Neruokpuk Quartzite and underlying units locally contain occ ...
... sets a minimum age of Late Ordovician for the quartzite. Thus, little doubt remains that the Neruokpuk Quartzite and underlying strata are Precambrian, but a more definite age assignment is not yet possible. Mineral resources.-Although the Neruokpuk Quartzite and underlying units locally contain occ ...
Karson, J.A., and Lawrence, R.M., 1997.
... metamorphic core complexes of the Cordilleran region (Lister and Davis, 1989) and can be regarded as an oceanic core complexes (Brown and Karson, 1988; Karson, 1990; Mutter and Karson, 1992). Juxtaposition of highly faulted and thinned crust with younger, much less deformed terrains suggests that th ...
... metamorphic core complexes of the Cordilleran region (Lister and Davis, 1989) and can be regarded as an oceanic core complexes (Brown and Karson, 1988; Karson, 1990; Mutter and Karson, 1992). Juxtaposition of highly faulted and thinned crust with younger, much less deformed terrains suggests that th ...
Geol Soc London Spec Publ 204 2002
... Tectonic setting of SE Asia and western Pacific SE Asia and the SW Pacific are dominated by convergence between the Eurasian, the Indian Australian and the Pacific plates (Fig. 1). In addition, the Philippine Sea plate, which lies between the Pacific and Eurasian plates, has played a crucial role i ...
... Tectonic setting of SE Asia and western Pacific SE Asia and the SW Pacific are dominated by convergence between the Eurasian, the Indian Australian and the Pacific plates (Fig. 1). In addition, the Philippine Sea plate, which lies between the Pacific and Eurasian plates, has played a crucial role i ...
aircurrents - AIR Worldwide
... that beneath the NMSZ lies a region of lower crust and upper mantle that is weak. Both geological and geophysical data support an understanding of the NMSZ as the remnant of a rift that 600 million years ago failed to separate fully to form an ocean basin. Geologists have named the failed rift the “ ...
... that beneath the NMSZ lies a region of lower crust and upper mantle that is weak. Both geological and geophysical data support an understanding of the NMSZ as the remnant of a rift that 600 million years ago failed to separate fully to form an ocean basin. Geologists have named the failed rift the “ ...
Subcontinental Lithosphere
... ing near the surface to create intraplate volcanoes. As we shall see in a subsequent lecture, sediment appears often, if not always, to be subducted along with the oceanic crust. This subducted sediment would also contribute to incompatible element enrichment of plumes. Varying amounts, types, and a ...
... ing near the surface to create intraplate volcanoes. As we shall see in a subsequent lecture, sediment appears often, if not always, to be subducted along with the oceanic crust. This subducted sediment would also contribute to incompatible element enrichment of plumes. Varying amounts, types, and a ...
7. Early Evolution of the South Atlantic Ocean: Role of the Rifting
... tensional phase the continental crust is thinned. If sedimentary cover exists, typical tilted fault blocks appear; their angle of tilting may reach 20 to 30 degrees for values of stretching of the continental crust greater than a factor of 2 (LePichon and Sibuet, 1981). The tilted fault blocks form ...
... tensional phase the continental crust is thinned. If sedimentary cover exists, typical tilted fault blocks appear; their angle of tilting may reach 20 to 30 degrees for values of stretching of the continental crust greater than a factor of 2 (LePichon and Sibuet, 1981). The tilted fault blocks form ...
WalkerJ_JGR_95(B13)21483 - KU ScholarWorks
... Plateau itself. Considerationof the chemical data and publishedgeophysicaldata argue that the subPlateau mantle is mechanically detachedfrom the overlying continental lithosphere, and that in this section of the plateau the thermal structureof the asthenosphereis not responsiblefor the formation or ...
... Plateau itself. Considerationof the chemical data and publishedgeophysicaldata argue that the subPlateau mantle is mechanically detachedfrom the overlying continental lithosphere, and that in this section of the plateau the thermal structureof the asthenosphereis not responsiblefor the formation or ...
Alteration of the oceanic lithosphere and its implications for seafloor
... biological importance for the global marine system and for subduction zone processes. Serpentinization involves hydration of olivine, the dominant mineral in the oceanic mantle, and typically incorporates >10 weight % H2O into the rocks. Hydration reactions are accompanied by a 20-40% increase in v ...
... biological importance for the global marine system and for subduction zone processes. Serpentinization involves hydration of olivine, the dominant mineral in the oceanic mantle, and typically incorporates >10 weight % H2O into the rocks. Hydration reactions are accompanied by a 20-40% increase in v ...
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.