Time-Space Development of an External Brine
... Large degrees of mid-Tertiary extension in west central Nevada is documented in a number of areas in the western Great Basin (Proffett, 1977; Seedorff, 1991; Hudson and Geissman, 1991; John, 1995). At least two episodes of extension are recorded in the region of the Humboldt mafic complex. Young til ...
... Large degrees of mid-Tertiary extension in west central Nevada is documented in a number of areas in the western Great Basin (Proffett, 1977; Seedorff, 1991; Hudson and Geissman, 1991; John, 1995). At least two episodes of extension are recorded in the region of the Humboldt mafic complex. Young til ...
Intra-Panthalassa Ocean subduction zones revealed by fossil arcs
... Lower–Middle Jurassic deep-oceanic radiolarian-bearing sequence without evidence for volcanism17 . Taxonomic composition of the radiolarian assemblages indicate that the second-generation island arc complex was formed ∼2,000 km away from the Asian continental margin17 . Faunal17 and palaeomagnetic d ...
... Lower–Middle Jurassic deep-oceanic radiolarian-bearing sequence without evidence for volcanism17 . Taxonomic composition of the radiolarian assemblages indicate that the second-generation island arc complex was formed ∼2,000 km away from the Asian continental margin17 . Faunal17 and palaeomagnetic d ...
Document
... Model for sea-floor spreading showing expansion of ocean ridges (divergent) and arc-trench (convergent) systems. Three lithospheric plates are shown moving over the weak low-velocity zone of the upper mantle. Magmas are produced in arcs by heating along the subduction zone. Deep earthquakes are conc ...
... Model for sea-floor spreading showing expansion of ocean ridges (divergent) and arc-trench (convergent) systems. Three lithospheric plates are shown moving over the weak low-velocity zone of the upper mantle. Magmas are produced in arcs by heating along the subduction zone. Deep earthquakes are conc ...
ES3210 - Gold Deposits
... In Archean greenstone belts, other types of Au deposits (formed at different crustal levels) have become juxtaposed against orogenic gold deposits as a consequence of progressive long term tectonism and metamorphism. ...
... In Archean greenstone belts, other types of Au deposits (formed at different crustal levels) have become juxtaposed against orogenic gold deposits as a consequence of progressive long term tectonism and metamorphism. ...
An Entirely New 3D-View of the Crustal and Mantle Structure of a
... The upper brittle continental crust tends to be a seismically poorly reflective layer, practically a blind zone (Figure 2). The top of the crystalline basement is rarely a significant reflection. Most of the times, it was tentatively interpreted at the basal termination of the reflective and stratif ...
... The upper brittle continental crust tends to be a seismically poorly reflective layer, practically a blind zone (Figure 2). The top of the crystalline basement is rarely a significant reflection. Most of the times, it was tentatively interpreted at the basal termination of the reflective and stratif ...
Watch Faults Grow Before Your Very Eyes in a Deformational Sandbox
... observed in deformation experiments, fault types can be more easily associated to a specific connotation; i.e. extension or contraction. In map view, faults are usually arranged in sets with consistent orientation and regular spacing. Do these faults form all at the same time? Does the number of fau ...
... observed in deformation experiments, fault types can be more easily associated to a specific connotation; i.e. extension or contraction. In map view, faults are usually arranged in sets with consistent orientation and regular spacing. Do these faults form all at the same time? Does the number of fau ...
Watch Faults Grow Before Your Very Eyes in a Deformational Sandbox
... observed in deformation experiments, fault types can be more easily associated to a specific connotation; i.e. extension or contraction. In map view, faults are usually arranged in sets with consistent orientation and regular spacing. Do these faults form all at the same time? Does the number of fau ...
... observed in deformation experiments, fault types can be more easily associated to a specific connotation; i.e. extension or contraction. In map view, faults are usually arranged in sets with consistent orientation and regular spacing. Do these faults form all at the same time? Does the number of fau ...
Chapter 32: Plate Tectonics: A Working Model for the Earth
... folding of the continental margin itself produces a thickened continental edge that enhances the mountain range. The Andes of South America and the Cascades of the northwestern United States are good examples of this sort of tectonic relationship (see Fig. 32.7). The last type of convergent plate b ...
... folding of the continental margin itself produces a thickened continental edge that enhances the mountain range. The Andes of South America and the Cascades of the northwestern United States are good examples of this sort of tectonic relationship (see Fig. 32.7). The last type of convergent plate b ...
chapter4 - Geological Sciences
... Relative dating places events in sequential order but does not tell us how long ago an event took place. The principles of relative dating provided geologists with a means to interpret geologic history and develop a relative geologic time scale. ...
... Relative dating places events in sequential order but does not tell us how long ago an event took place. The principles of relative dating provided geologists with a means to interpret geologic history and develop a relative geologic time scale. ...
PLATE TECTONICS: BIRTH OF A THEORY
... Paleomagnetism The ancient magnetic fields of the Earth. We can infer the orientation of ancient magnetic fields because some types of rocks record this information at the time of their formation. Pangaea The supercontinent that broke up about 200 million years ago to form the various continents ...
... Paleomagnetism The ancient magnetic fields of the Earth. We can infer the orientation of ancient magnetic fields because some types of rocks record this information at the time of their formation. Pangaea The supercontinent that broke up about 200 million years ago to form the various continents ...
Geology - Geostud
... simulates the effects of the 3-D crustal model on conversions from each specific P-wave. For each event and each station a vertical section in a 3-D model is cut in the direction toward the earthquake. The 3-D Vp model is adjusted from the velocity model used for the ray tracing; the eastward-dippin ...
... simulates the effects of the 3-D crustal model on conversions from each specific P-wave. For each event and each station a vertical section in a 3-D model is cut in the direction toward the earthquake. The 3-D Vp model is adjusted from the velocity model used for the ray tracing; the eastward-dippin ...
Planet Earth
... Types of Rock Movement in Earthquakes - where the plates meet, the rock is under great pressure, which can make it bend and stretch when the pressure is too great, the rock breaks suddenly creating a fault - there are three types of movement, of the tectonic plates, along a fault - Normal Faults, (p ...
... Types of Rock Movement in Earthquakes - where the plates meet, the rock is under great pressure, which can make it bend and stretch when the pressure is too great, the rock breaks suddenly creating a fault - there are three types of movement, of the tectonic plates, along a fault - Normal Faults, (p ...
Chapter 9 - Government of New Brunswick
... Bedrock in the Madawaska Uplands can be broadly divided into two sections. The northern section contains steeply dipping Ordovician to Devonian metasedimentary rocks, some of which are calcareous. The southern section forms a plateau of Devonian granites with minor sedimentary and volcanic rocks of ...
... Bedrock in the Madawaska Uplands can be broadly divided into two sections. The northern section contains steeply dipping Ordovician to Devonian metasedimentary rocks, some of which are calcareous. The southern section forms a plateau of Devonian granites with minor sedimentary and volcanic rocks of ...
Geologic History of the Tucson Mountains Jan C. Rasmussen
... and fine-grained granite. These rocks and associated volcanics, such as the Cat Mountain Tuff (rhyolite), in the northern Tucson Mountains have a characteristic metaluminous alkali-calcic geochemistry on whole rock samples. Lead-copper-silver mineralization is associated with the Late Cretaceous ign ...
... and fine-grained granite. These rocks and associated volcanics, such as the Cat Mountain Tuff (rhyolite), in the northern Tucson Mountains have a characteristic metaluminous alkali-calcic geochemistry on whole rock samples. Lead-copper-silver mineralization is associated with the Late Cretaceous ign ...
Atlantic volcanic margins: a comparative study
... features, subsidence modelling and crustal thickness variations, have been discussed by Skogseid et al. (I 992a) and Skogseid (1994). They suggest that North Atlantic volcanic margin formation was preceded by a rift phase lasting for about 18-20 Ma before break-up (Table 3). The lithospheric extensi ...
... features, subsidence modelling and crustal thickness variations, have been discussed by Skogseid et al. (I 992a) and Skogseid (1994). They suggest that North Atlantic volcanic margin formation was preceded by a rift phase lasting for about 18-20 Ma before break-up (Table 3). The lithospheric extensi ...
Seismic reflection image of the Great Sumatra
... Beneath the frontal part of the wedge, two steeply dipping (31, 35) thrust aftershocks occurred at 17.5 km depth8, falling close to the oceanic Moho (Figure 4)7-8. Two other deep thrust events (16, 22 km depth) with steep dips (33, 41) were reported in this area, and at least four more occurred ...
... Beneath the frontal part of the wedge, two steeply dipping (31, 35) thrust aftershocks occurred at 17.5 km depth8, falling close to the oceanic Moho (Figure 4)7-8. Two other deep thrust events (16, 22 km depth) with steep dips (33, 41) were reported in this area, and at least four more occurred ...
Temperature Models for Mexican Subduction Zone
... defined by a 20 ºC/km thermal gradient for the continental crust. This value is in agreement with the back arc thermal gradient of 17.8 - 20.2 ºC/Km reported by Ziagos et al. (1985). The landward boundary is located far away (~ 400 km) from the coupled plate interface; therefore this boundary condit ...
... defined by a 20 ºC/km thermal gradient for the continental crust. This value is in agreement with the back arc thermal gradient of 17.8 - 20.2 ºC/Km reported by Ziagos et al. (1985). The landward boundary is located far away (~ 400 km) from the coupled plate interface; therefore this boundary condit ...
Atlantic Ocean
... Over 70,000 kilometers (43,000 miles) in length Twenty-three percent of Earth’s surface Winds through all major oceans ...
... Over 70,000 kilometers (43,000 miles) in length Twenty-three percent of Earth’s surface Winds through all major oceans ...
Slab flattening trigger for isotopic disturbance and magmatic flare
... shallow subduction is commonly invoked to explain the termination and/or migration of arc magmatism (Dumitru et al., 1991; Saleeby, 2003). However, during slab flattening, subduction accretion assemblages may be transported into the magmatic source region of an active arc. Subsequent partial melting ...
... shallow subduction is commonly invoked to explain the termination and/or migration of arc magmatism (Dumitru et al., 1991; Saleeby, 2003). However, during slab flattening, subduction accretion assemblages may be transported into the magmatic source region of an active arc. Subsequent partial melting ...
WEST-HIMALAYA: Island arc / continent collision
... interpretations suggested, closure of the Karakoram–Kohistan Suture postdates collision of the Kohistan arc with India. In any case, same fission track apatite ages on both sides of this suture show that no or imperceptible vertical differential movement has taken place along this fault zone since t ...
... interpretations suggested, closure of the Karakoram–Kohistan Suture postdates collision of the Kohistan arc with India. In any case, same fission track apatite ages on both sides of this suture show that no or imperceptible vertical differential movement has taken place along this fault zone since t ...
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 “ ...
Focus in Action Learning Pack
... Diamonds are used in surgery, razor blades, computers, dentistry, oil drilling and a glasscutter's wheel has diamonds embedded in it. ...
... Diamonds are used in surgery, razor blades, computers, dentistry, oil drilling and a glasscutter's wheel has diamonds embedded in it. ...
PC Minerals
... The rocks on Ping Chau probably formed in a saline lake environment. Gradual evaporation of the lake water caused minerals to precipitate out of the saline water. Two commonest minerals that formed in the evaporite are halite and gypsum. Since halite is easily dissolved, gypsum becomes the more read ...
... The rocks on Ping Chau probably formed in a saline lake environment. Gradual evaporation of the lake water caused minerals to precipitate out of the saline water. Two commonest minerals that formed in the evaporite are halite and gypsum. Since halite is easily dissolved, gypsum becomes the more read ...
Tectonic controls on the late Miocene–Holocene volcanic eruptions
... at 16–24 km and a high velocity body at 25–40 km (Qin et al., 2000a; Wang et al., 2002; Wang and Huangfu, 2004). The low velocity body is proposed to be a magma body or partly-molten material (Qin et al., 2000b). In addition, the depth to the top of the high conducting layer in the upper mantle is s ...
... at 16–24 km and a high velocity body at 25–40 km (Qin et al., 2000a; Wang et al., 2002; Wang and Huangfu, 2004). The low velocity body is proposed to be a magma body or partly-molten material (Qin et al., 2000b). In addition, the depth to the top of the high conducting layer in the upper mantle is s ...
Volcanoes and Igneous Activity Earth - Chapter 4
... Over 70,000 kilometers (43,000 miles) in length Twenty-three percent of Earth’s surface Winds through all major oceans ...
... Over 70,000 kilometers (43,000 miles) in length Twenty-three percent of Earth’s surface Winds through all major oceans ...
Algoman orogeny
The Algoman orogeny, known as the Kenoran orogeny in Canada, was an episode of mountain-building (orogeny) during the Late Archean Eon that involved repeated episodes of continental collisions, compressions and subductions. The Superior province and the Minnesota River Valley terrane collided about 2,700 to 2,500 million years ago. The collision folded the Earth's crust and produced enough heat and pressure to metamorphose the rock. Blocks were added to the Superior province along a 1,200 km (750 mi) boundary that stretches from present-day eastern South Dakota into the Lake Huron area. The Algoman orogeny brought the Archaen Eon to a close, about 2,500 million years ago; it lasted less than 100 million years and marks a major change in the development of the earth’s crust.The Canadian shield contains belts of metavolcanic and metasedimentary rocks formed by the action of metamorphism on volcanic and sedimentary rock. The areas between individual belts consist of granites or granitic gneisses that form fault zones. These two types of belts can be seen in the Wabigoon, Quetico and Wawa subprovinces; the Wabigoon and Wawa are of volcanic origin and the Quetico is of sedimentary origin. These three subprovinces lie linearly in southwestern- to northeastern-oriented belts about 140 km (90 mi) wide on the southern portion of the Superior Province.The Slave province and portions of the Nain province were also affected. Between about 2,000 and 1,700 million years ago these combined with the Sask and Wyoming cratons to form the first supercontinent, the Kenorland supercontinent.