Bebout Metamorphic chemical geodynamics of subduction zones
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
Metamorphic chemical geodynamics of subduction zones
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
Mineral Resources in the Eastern Alps and Adjoining Areas
... suture zone situated at the northern margin of Gondwana, from which they split off during the Cambrian-Ordovician and Silurian. Cambrian (?) rifting at the active Gondwana margin was interrupted by a short-lived Orodovician orogenic event. After terrane drifting to the north, the final Variscan coll ...
... suture zone situated at the northern margin of Gondwana, from which they split off during the Cambrian-Ordovician and Silurian. Cambrian (?) rifting at the active Gondwana margin was interrupted by a short-lived Orodovician orogenic event. After terrane drifting to the north, the final Variscan coll ...
Chapter 21: Metamorphism
... • Uplift and erosion • Metamorphism often continues after major deformation ceases § Metamorphic pattern is simpler than the structural one • Pattern of increasing metamorphic grade from both directions toward the core area From Understanding Earth, Press and Siever. Freeman. ...
... • Uplift and erosion • Metamorphism often continues after major deformation ceases § Metamorphic pattern is simpler than the structural one • Pattern of increasing metamorphic grade from both directions toward the core area From Understanding Earth, Press and Siever. Freeman. ...
geology of the storkollen blankenberg area, kragerø, norway
... irregular dip to the south. The texture of the slickensides indicates that at least in one movement, the south (kragerøite) wall moved down and to the west relative to the north wall. The larger eastern rutile mine follows the second fault for about twenty meters at its entrance tunnel, before turni ...
... irregular dip to the south. The texture of the slickensides indicates that at least in one movement, the south (kragerøite) wall moved down and to the west relative to the north wall. The larger eastern rutile mine follows the second fault for about twenty meters at its entrance tunnel, before turni ...
Geological transport directions in Peninsular Malaysia
... Multiple Deformations. The tectonic history ofPeninsular Malaysia already indicates that multiple deformations can be expected. Many publications, however, have only stated as ev idence "differences in structural complexity, or in metamorphic grade, or strong fo lding, or microfolding and crenulatio ...
... Multiple Deformations. The tectonic history ofPeninsular Malaysia already indicates that multiple deformations can be expected. Many publications, however, have only stated as ev idence "differences in structural complexity, or in metamorphic grade, or strong fo lding, or microfolding and crenulatio ...
Characteristics and Petrogenesis of Alaskan-Type Ultramafic
... included in the Alaskan-type group. Exceptions are the basal ultramafic rocks of the tholeiitic, informally named La Perouse layered gabbro (Himmelberg and Loney, 1981; Loney and Himmelberg, 1983) in the Fairweather Range, the ultramafic rocks associated with the norite, diorite, granodiorite comple ...
... included in the Alaskan-type group. Exceptions are the basal ultramafic rocks of the tholeiitic, informally named La Perouse layered gabbro (Himmelberg and Loney, 1981; Loney and Himmelberg, 1983) in the Fairweather Range, the ultramafic rocks associated with the norite, diorite, granodiorite comple ...
Chi, G., Liu, Y. and Dube, B. 2009. Relationship between CO2
... (Sanborn-Barrie et al., 2004, and references therein). Metamorphic grade increases from greenschist facies in the middle of the greenstone belt to amphibole facies at the margin of the belt, which is surrounded by granitoid intrusions, and the boundaries between metamorphic zones (isograds) are broa ...
... (Sanborn-Barrie et al., 2004, and references therein). Metamorphic grade increases from greenschist facies in the middle of the greenstone belt to amphibole facies at the margin of the belt, which is surrounded by granitoid intrusions, and the boundaries between metamorphic zones (isograds) are broa ...
3 - Blinklearning
... A practical way to explain the layers of the geosphere is to make a chart where students can compare depth, density, state of the materials and its composition. This chart will help students to easily follow the explanations and understand the contents ...
... A practical way to explain the layers of the geosphere is to make a chart where students can compare depth, density, state of the materials and its composition. This chart will help students to easily follow the explanations and understand the contents ...
Orogenic Belts and Orogenic Sediment Provenance
... gives rise to “ophiolite-capped thrust belts” (Cawood 1991), the archetypal example being the Northern Oman orogen assembled at Late Cretaceous times (Searle and Stevens 1984). The pro-side of the obduction orogen is a thick-skinned thrust belt, beneath which continental blueschists and eclogites of ...
... gives rise to “ophiolite-capped thrust belts” (Cawood 1991), the archetypal example being the Northern Oman orogen assembled at Late Cretaceous times (Searle and Stevens 1984). The pro-side of the obduction orogen is a thick-skinned thrust belt, beneath which continental blueschists and eclogites of ...
constraints, geotectonic setting and basin development Saxo
... metamorphosed rocks of the Ediacaran period in the German part of the Saxo-Thuringian Zone at the northeastern margin of the Bohemian Massif. The geotectonic setting during the formation of Ediacaran rock units is characterized by Cadomian orogenic processes from c. 650–540 Ma at the periphery of th ...
... metamorphosed rocks of the Ediacaran period in the German part of the Saxo-Thuringian Zone at the northeastern margin of the Bohemian Massif. The geotectonic setting during the formation of Ediacaran rock units is characterized by Cadomian orogenic processes from c. 650–540 Ma at the periphery of th ...
Igneous Rock Associations 8. Arc Magmatism II: Geo
... settings, and are known as high-alumina basalt. Although their origin is unclear, their low MgO content suggests that they are fractionated (by removal of olivine and augite) from a more mafic parent. The high Al2O3 implies that plagioclase was not a liquidus phase. Two suites, or collections of mag ...
... settings, and are known as high-alumina basalt. Although their origin is unclear, their low MgO content suggests that they are fractionated (by removal of olivine and augite) from a more mafic parent. The high Al2O3 implies that plagioclase was not a liquidus phase. Two suites, or collections of mag ...
Laramide crustal thickening event in the Rocky Mountain Foreland
... and Great Plains at up to 2 km average elevation. The same shear tractions that Brewer et al. [1980] invoked to cause the Wind River range overthrust may also have dragged and transported ductile lower crust from within the Sevier orogen in the Southwest, and emplaced it under ...
... and Great Plains at up to 2 km average elevation. The same shear tractions that Brewer et al. [1980] invoked to cause the Wind River range overthrust may also have dragged and transported ductile lower crust from within the Sevier orogen in the Southwest, and emplaced it under ...
Polyphasal brecciation history revealing the nature and depth of
... veins (Fig. 4A, B). Chlorite/epidote veins form discrete, light green, up to 10 cm-long veinlets, which in outcrop and in thin-section are observed to be dissected and truncated by the quartz veins (Fig. 4A, B). The chlorite/ epidote veins are between 1 and 2 mm thick, consisting of opaque, cryptocr ...
... veins (Fig. 4A, B). Chlorite/epidote veins form discrete, light green, up to 10 cm-long veinlets, which in outcrop and in thin-section are observed to be dissected and truncated by the quartz veins (Fig. 4A, B). The chlorite/ epidote veins are between 1 and 2 mm thick, consisting of opaque, cryptocr ...
Snake River Plain-Yellowstone Plateau province, Idaho and Wyoming
... others, 1975) have suggested that at least the eastern Snake River Plain is the track of a deep mantle plume (or hot spot) over which the continent has migrated at a steady rate. It has also been proposed that the Snake River Plain is a zone of crustal extension (Hamilton and Myers, 1966) or an east ...
... others, 1975) have suggested that at least the eastern Snake River Plain is the track of a deep mantle plume (or hot spot) over which the continent has migrated at a steady rate. It has also been proposed that the Snake River Plain is a zone of crustal extension (Hamilton and Myers, 1966) or an east ...
norphisi1 ill tile (ollwirucx Mountain Quadrangle, Northl
... serpentinized equivalents. In the Condrey Mountain quadrangle, probably more than 90 percent of the ultramafic rocks is serpentinized. Most of the serpentinite is composed of antigorite formed by metamorphism of serpentinized ultramafic rocks; it is not known whether the metamorphism was of the same ...
... serpentinized equivalents. In the Condrey Mountain quadrangle, probably more than 90 percent of the ultramafic rocks is serpentinized. Most of the serpentinite is composed of antigorite formed by metamorphism of serpentinized ultramafic rocks; it is not known whether the metamorphism was of the same ...
Fe isotopes: An emerging technique for understanding modern and
... region). The oceanic and continental igneous flux has δ56Fe = 0‰, indicating that the bulk of the mantle, with the exception of isolated domains that reside largely in the lithosphere (dot pattern), is isotopically homogeneous, as are bulk clastic rocks that have low-C and -S contents, despite an in ...
... region). The oceanic and continental igneous flux has δ56Fe = 0‰, indicating that the bulk of the mantle, with the exception of isolated domains that reside largely in the lithosphere (dot pattern), is isotopically homogeneous, as are bulk clastic rocks that have low-C and -S contents, despite an in ...
The volcanic–plutonic connection as a stage for
... (Lindsay et al., 2001; Bachmann et al., 2002; Maughan et al., 2002), a rare assemblage in crystal-poor volcanic rocks (Nakada, 1991; Deer et al., 1992) but common in granodiorite batholiths (e.g., Bateman and Chappell, 1979). One noticeable difference is the higher abundance of quartz and K-feldspar ...
... (Lindsay et al., 2001; Bachmann et al., 2002; Maughan et al., 2002), a rare assemblage in crystal-poor volcanic rocks (Nakada, 1991; Deer et al., 1992) but common in granodiorite batholiths (e.g., Bateman and Chappell, 1979). One noticeable difference is the higher abundance of quartz and K-feldspar ...
The American Cordillera: Part III, The North American Taphrogen
... Campanian—Maastrichtian time. This extension produced no known surface-breaking faults, and may have been restricted to mid-crustal rocks. Coeval with extension in the hinterland region, major thinskinned thrust systems propagated eastward into Wyoming in the frontal Sevier belt. The contemporaneity ...
... Campanian—Maastrichtian time. This extension produced no known surface-breaking faults, and may have been restricted to mid-crustal rocks. Coeval with extension in the hinterland region, major thinskinned thrust systems propagated eastward into Wyoming in the frontal Sevier belt. The contemporaneity ...
Tectonic history of the Chihuahua trough, Mexico
... structural grain of the region; timing is consistent with oldest known strike-slip movement along the Texas Lineament zone (Stockton Pass, Arizona ca. 1,370±70 Ma). Following deposition of the Carrizo Mountain Group, inferred 1,260-1,160 Ma De Baca rifting affected areas to the north and northwest o ...
... structural grain of the region; timing is consistent with oldest known strike-slip movement along the Texas Lineament zone (Stockton Pass, Arizona ca. 1,370±70 Ma). Following deposition of the Carrizo Mountain Group, inferred 1,260-1,160 Ma De Baca rifting affected areas to the north and northwest o ...
The Rice Lake mine trend, Manitoba
... debris and should stay well back from overhanging cliffs or steep faces. Participants must stay clear of abrupt drop-offs at all times, stay with the field trip group, and follow instructions from leaders. Participants are asked to refrain from hammering rock. It represents a significant hazard to t ...
... debris and should stay well back from overhanging cliffs or steep faces. Participants must stay clear of abrupt drop-offs at all times, stay with the field trip group, and follow instructions from leaders. Participants are asked to refrain from hammering rock. It represents a significant hazard to t ...
Ocean Drilling Program Initial Reports Volume 160
... North African plate to the south, perhaps as a marginal crustal fragment. The nature of the basement of the Eratosthenes Seamount is unknown, but it might represent transitional continental crust, intruded by mafic igneous rocks, in view of the strong magnetic anomaly beneath the seamount and adjace ...
... North African plate to the south, perhaps as a marginal crustal fragment. The nature of the basement of the Eratosthenes Seamount is unknown, but it might represent transitional continental crust, intruded by mafic igneous rocks, in view of the strong magnetic anomaly beneath the seamount and adjace ...
The Exposed Passive Margin of North America in Western Cuba
... The Mesozoic successions of western Cuba, now exposed in the Guaniguanico terrane, were deposited to the east of the present NE Yucatan coast. The evolution of these passive margin successions encompasses the syn-rift stage (Early Jurassic?Callovian/early Oxfordian), drift stage (?Callovian/middle O ...
... The Mesozoic successions of western Cuba, now exposed in the Guaniguanico terrane, were deposited to the east of the present NE Yucatan coast. The evolution of these passive margin successions encompasses the syn-rift stage (Early Jurassic?Callovian/early Oxfordian), drift stage (?Callovian/middle O ...
Chapter 17 Basins in arc-continent collisions
... ways. Trenches and trench-slope basins form along the boundary between the two plates in response to flexure of the subducting slab and extension of the upper plate driven by basal tectonic erosion (Fig. 17.2; von Huene and Scholl, 1991; Underwood and Moore, 1995; Underwood et al., 2003). Forearc ba ...
... ways. Trenches and trench-slope basins form along the boundary between the two plates in response to flexure of the subducting slab and extension of the upper plate driven by basal tectonic erosion (Fig. 17.2; von Huene and Scholl, 1991; Underwood and Moore, 1995; Underwood et al., 2003). Forearc ba ...
Great Lakes tectonic zone
The Great Lakes tectonic zone is bounded by South Dakota at its tip and heads northeast to south of Duluth, Minnesota, then heads east through northern Wisconsin, Marquette, Michigan, and then trends more northeasterly to skim the northern-most shores of lakes Michigan and Huron before ending in the Sudbury, Ontario, Canada, area.During the Late Archean Era the Algoman orogeny added landmass to the Superior province by volcanic activity and continental collision along a boundary that stretches from present-day South Dakota, U.S., into the Lake Huron region near Sudbury, Ontario, Canada.This crustal boundary is the Great Lakes tectonic zone. It is 1,400 km (870 mi) long, and separates the older Archean gneissic terrane to the south from younger Late Archean greenstone-granite terrane to the north.The zone is characterized by active compression during the Algoman orogeny (about 2,700 million years ago), a pulling-apart (extensional) tectonics (2,450 to 2,100 million years ago), a second compression during the Penokean orogeny (1,900 to 1,850 million years ago), a second extension during Middle Proterozoic time (1,600 million years ago) and minor reactivation during Phanerozoic time (the past 500 million years).Collision began along the Great Lakes tectonic zone (GLTZ) with the Algoman mountain-building event and continued for tens of millions of years. During the formation of the GLTZ, the gneissic Minnesota River Valley subprovince was thrust up onto the Superior province's edge as it consumed the Superior province's oceanic crust. Fragmentation of the Kenorland supercontinent began 2,450 million years ago and was completed by 2,100 million years ago. The Wyoming province is the continental landmass that is hypothesized to have rifted away from the southern Superior province portion of Kenorland, before moving rapidly west and docking with the Laurentia supercontinent 1,850 to 1,715 million years ago. Sedimentation from the GLTZ-rifting environment continued into the Penokean orogeny, which is the next major tectonic event in the Great Lakes region. Several earthquakes have been documented in Minnesota, Michigan's Upper Peninsula and Sudbury in the last 120 years along the GLTZ.