Earth Science Chapter 18: Volcanic Activity Chapter Overview
... Sometimes, when magma intrudes into parallel rock layers close to Earth’s surface, some of the rocks bow upward as a result of the intense heat and pressure of the magma body. When the magma solidifies, a laccolith forms. A laccolith is a mushroom-shaped pluton with a round top and flat bottom. Lacc ...
... Sometimes, when magma intrudes into parallel rock layers close to Earth’s surface, some of the rocks bow upward as a result of the intense heat and pressure of the magma body. When the magma solidifies, a laccolith forms. A laccolith is a mushroom-shaped pluton with a round top and flat bottom. Lacc ...
Convergent-Boundary Mountains
... mountain ranges. • Orogeny results in broad, linear regions of deformation known as orogenic belts, most of which are associated with plate boundaries. • Convergent boundaries are the location of the greatest variety and the tallest orogenic belts. • The compressive forces at these boundaries may ca ...
... mountain ranges. • Orogeny results in broad, linear regions of deformation known as orogenic belts, most of which are associated with plate boundaries. • Convergent boundaries are the location of the greatest variety and the tallest orogenic belts. • The compressive forces at these boundaries may ca ...
Petrology and geochemistry of the Tertiary alkaline intrusive rocks at
... Field observations, petrography, geochemical data and the results of K–Ar dating are presented for Oligocene (c. 30–29 Ma) alkaline intrusions at the former township of Doupov (Duppau) in the central part of the Doupovské hory Volcanic Complex (DHVC). The Doupov Intrusive Complex (DIC) is a very lim ...
... Field observations, petrography, geochemical data and the results of K–Ar dating are presented for Oligocene (c. 30–29 Ma) alkaline intrusions at the former township of Doupov (Duppau) in the central part of the Doupovské hory Volcanic Complex (DHVC). The Doupov Intrusive Complex (DIC) is a very lim ...
Sea-Floor Spreading
... • Sea-floor spreading and subduction often work together. • They move the ocean floor as if it were on a giant conveyor belt. ...
... • Sea-floor spreading and subduction often work together. • They move the ocean floor as if it were on a giant conveyor belt. ...
Evolution of the Precambrian Rocks of Yellowstone National Park
... granitic bodies, the Crevice and Hellroaring Plutons. Montgomery (1982) determined an age of 2.73 to 2.79 Ga for one of the plutons in the northern portion of Yellowstone National Park, 0.3 km east of Tower Junction. Casella, et al. (1982) hypothesized that the plutons have a similar geologic histor ...
... granitic bodies, the Crevice and Hellroaring Plutons. Montgomery (1982) determined an age of 2.73 to 2.79 Ga for one of the plutons in the northern portion of Yellowstone National Park, 0.3 km east of Tower Junction. Casella, et al. (1982) hypothesized that the plutons have a similar geologic histor ...
New constraints on the sedimentation and uplift history of the
... The Andaman-Nicobar Islands are part of an accretionary complex that forms the outer arc ridge of the northern Sunda subduction zone (Fig. 1). The Andaman Islands are in the southeastern part of the Bay of Bengal and make up part of a 3000– 5000 km chain that runs from the Myanmar Arakan-Yoma down t ...
... The Andaman-Nicobar Islands are part of an accretionary complex that forms the outer arc ridge of the northern Sunda subduction zone (Fig. 1). The Andaman Islands are in the southeastern part of the Bay of Bengal and make up part of a 3000– 5000 km chain that runs from the Myanmar Arakan-Yoma down t ...
Laramie Peak shear system, central Laramie
... Laramie Peak shear zone by including another NE –SW-striking zone of concentrated shear strain, the North Laramie River high-strain zone, that occurs SE of the Fletcher Park shear zone (Fig. 2). Recently, Allard (2003) has recognized additional evidence of heterogeneous, high strain deformation to t ...
... Laramie Peak shear zone by including another NE –SW-striking zone of concentrated shear strain, the North Laramie River high-strain zone, that occurs SE of the Fletcher Park shear zone (Fig. 2). Recently, Allard (2003) has recognized additional evidence of heterogeneous, high strain deformation to t ...
9.2 Metallic mineral occurrences in the shield and deposit types
... sizes of trial excavations, the ancient miners effectively differentiated between bull and goldbearing quartz veins; and exploration was so comprehensive that it is almost a truism that an ancient trial pit or excavation can be found at any outcrop of quartz vein in the shield that shows promise for ...
... sizes of trial excavations, the ancient miners effectively differentiated between bull and goldbearing quartz veins; and exploration was so comprehensive that it is almost a truism that an ancient trial pit or excavation can be found at any outcrop of quartz vein in the shield that shows promise for ...
Chapter 23 The Geology of the Mesozoic Era
... Rising Salt Domes tilt sediments Concentrate petroleum ...
... Rising Salt Domes tilt sediments Concentrate petroleum ...
3:n:1:di - EVA - Universidad de la República
... a thin film around and separates the solid mineral grains. The mobile asthenosphere directly beneath the lithosphere is assumed to contain a few percent pole (the rotational pole of the Earth) in an ir- of molten material. regular, sinuous manner to produce what is called The pattern of convection c ...
... a thin film around and separates the solid mineral grains. The mobile asthenosphere directly beneath the lithosphere is assumed to contain a few percent pole (the rotational pole of the Earth) in an ir- of molten material. regular, sinuous manner to produce what is called The pattern of convection c ...
The Pace of Plutonism
... Abraham Werner [1749–1817]) believed that granites— along with all rocks—were precipitated from the oceans. According to the Neptunists, the granitic layer of the Earth was the oldest layer, upon which younger fossil-bearing layers were deposited. The Plutonists (originally proposed by Italian abbot ...
... Abraham Werner [1749–1817]) believed that granites— along with all rocks—were precipitated from the oceans. According to the Neptunists, the granitic layer of the Earth was the oldest layer, upon which younger fossil-bearing layers were deposited. The Plutonists (originally proposed by Italian abbot ...
The South-east African margin and its marine basins and ridge
... the Okavango dyke swarm follows a Pan-African trend developed in the late Proterozoic and early Paleozoic. In addition, not only did other Karoo dyke swarms also utilize pre-existing trends (Uken and Watkeys, 1997), but the site of the proposed plume head is at the intersection of three Precambrian ...
... the Okavango dyke swarm follows a Pan-African trend developed in the late Proterozoic and early Paleozoic. In addition, not only did other Karoo dyke swarms also utilize pre-existing trends (Uken and Watkeys, 1997), but the site of the proposed plume head is at the intersection of three Precambrian ...
Deformation of the Continental Crust
... Stacked Sheets of Continental Crust Due to Convergence of Continental ...
... Stacked Sheets of Continental Crust Due to Convergence of Continental ...
Metamorphic chemical geodynamics of subduction zones
... Fig. 3. P–T diagram showing regions of peak metamorphism and exhumation paths (lines indicating P–T history of rocks during their transit toward the surface) for selected HP and UHP metamorphic suites discussed in the text (see Table 2) and for which data are presented in Figs. 4, 5 and 7 (modified ...
... Fig. 3. P–T diagram showing regions of peak metamorphism and exhumation paths (lines indicating P–T history of rocks during their transit toward the surface) for selected HP and UHP metamorphic suites discussed in the text (see Table 2) and for which data are presented in Figs. 4, 5 and 7 (modified ...
Bebout Metamorphic chemical geodynamics of subduction zones
... Fig. 3. P–T diagram showing regions of peak metamorphism and exhumation paths (lines indicating P–T history of rocks during their transit toward the surface) for selected HP and UHP metamorphic suites discussed in the text (see Table 2) and for which data are presented in Figs. 4, 5 and 7 (modified ...
... Fig. 3. P–T diagram showing regions of peak metamorphism and exhumation paths (lines indicating P–T history of rocks during their transit toward the surface) for selected HP and UHP metamorphic suites discussed in the text (see Table 2) and for which data are presented in Figs. 4, 5 and 7 (modified ...
A narrowly spaced double-seismic zone in the subducting Nazca plate
... seem to connect both seismicity bands and may be interpreted as deep penetrating faults, which are (re)activated by fluid flow in a depth range between 105 km and 115 km (Figure 4). Above and below this depth range only a few events occur in the intermediate (mostly aseismic) layer. Thus, dehydratio ...
... seem to connect both seismicity bands and may be interpreted as deep penetrating faults, which are (re)activated by fluid flow in a depth range between 105 km and 115 km (Figure 4). Above and below this depth range only a few events occur in the intermediate (mostly aseismic) layer. Thus, dehydratio ...
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... The Sevier orogeny should not be confused with the Laramide orogeny which also affected parts of the western U.S.A. The former was older (Late Jurassic-Eocene) thin-skin tectonics; the latter was younger (latest Cretaceous-Eocene) thickskinned tectonics. Basement uplifts such as the Uinta Mountains ...
... The Sevier orogeny should not be confused with the Laramide orogeny which also affected parts of the western U.S.A. The former was older (Late Jurassic-Eocene) thin-skin tectonics; the latter was younger (latest Cretaceous-Eocene) thickskinned tectonics. Basement uplifts such as the Uinta Mountains ...
Continent formation through time
... when, how and where did the continental crust form? How did it differentiate and evolve through time? How has it has been pre- served in the geological record? This introductory review provides a background to these themes, and provides an outline of the contributions contained within this volume. ...
... when, how and where did the continental crust form? How did it differentiate and evolve through time? How has it has been pre- served in the geological record? This introductory review provides a background to these themes, and provides an outline of the contributions contained within this volume. ...
Timing and Tectonic Setting of Volcanogenic
... arc systems and marginal basins forming on both sides of Iapetus (Fig. 2). The closure of these multiple oceanic basins resulted in multiple orogenic episodes and complex structural histories. A consequence of this is that the extensional settings that host VMS deposits occur repeatedly over time an ...
... arc systems and marginal basins forming on both sides of Iapetus (Fig. 2). The closure of these multiple oceanic basins resulted in multiple orogenic episodes and complex structural histories. A consequence of this is that the extensional settings that host VMS deposits occur repeatedly over time an ...
of Earthquakes
... the crust above from the core below Seismic wave studies indicate the mantle, like the crust, is made of solid rock with only isolated pockets of magma Higher seismic wave velocity (8 km/sec) of mantle vs. crustal rocks indicate denser, ultramafic composition Crust + upper mantle = lithosphere, the ...
... the crust above from the core below Seismic wave studies indicate the mantle, like the crust, is made of solid rock with only isolated pockets of magma Higher seismic wave velocity (8 km/sec) of mantle vs. crustal rocks indicate denser, ultramafic composition Crust + upper mantle = lithosphere, the ...
Chapter 9 - LSU Geology & Geophysics
... – which are linear or arcuate deformation belts – in which many of the rocks have been • metamorphosed • and intruded by magma • thus forming plutons, especially batholiths ...
... – which are linear or arcuate deformation belts – in which many of the rocks have been • metamorphosed • and intruded by magma • thus forming plutons, especially batholiths ...
46_1996_Ilg et al_GSABull_Tectonic evolution in GC
... Grand Canyon (cf. Hawkins et al., 1996). The metavolcanic and metasedimentary rocks are interpreted to represent marine volcanic-arc sequences locally constructed on, or juxtaposed with, older (1.84 Ga) sialic crust and intruded by 1.74–1.71 Ga plutonic rocks. Primary structures such as relict pillo ...
... Grand Canyon (cf. Hawkins et al., 1996). The metavolcanic and metasedimentary rocks are interpreted to represent marine volcanic-arc sequences locally constructed on, or juxtaposed with, older (1.84 Ga) sialic crust and intruded by 1.74–1.71 Ga plutonic rocks. Primary structures such as relict pillo ...
GEOLOGIC TIME basic principles
... (foot wall). The layers were con8nuous (correla8on is not immediate but note the kinked bed edges along the fault) but have been cut by the fault. Hence, the fault is younger than the layers (it occurred aker the layers had formed) House Rock Junc8on, Arizona ©Alessandro Grippo ...
... (foot wall). The layers were con8nuous (correla8on is not immediate but note the kinked bed edges along the fault) but have been cut by the fault. Hence, the fault is younger than the layers (it occurred aker the layers had formed) House Rock Junc8on, Arizona ©Alessandro Grippo ...
Petrological models of magma evolution and deep crustal structure
... tholeiitic basal@ and the expected picritic composition of the parental mantle melts. In our model the initial liquid compositions are taken from melting experiments on spine1 lherzolites at lo-30 kbar pressure and span reasonable compositional differences over a depth range of melting. MELTS rigoro ...
... tholeiitic basal@ and the expected picritic composition of the parental mantle melts. In our model the initial liquid compositions are taken from melting experiments on spine1 lherzolites at lo-30 kbar pressure and span reasonable compositional differences over a depth range of melting. MELTS rigoro ...
Bedrock Geology along the Northern Margin of the Athabasca Basin
... According to existing maps (Slimmon, 1989), the far eastern part of the area studied is underlain by the same lithological unit as the far west; however, several significant differences indicate that this may not be the case. Both areas contain a variety of variably garnetiferous granitoid rocks, b ...
... According to existing maps (Slimmon, 1989), the far eastern part of the area studied is underlain by the same lithological unit as the far west; however, several significant differences indicate that this may not be the case. Both areas contain a variety of variably garnetiferous granitoid rocks, b ...
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.