METAMORPHIC ROCKS THE LANGUAGE OF THE EARTH – PART III
... maintained for a long period of time, minerals will tend to increase in size. • Foliation - As new platy minerals grow, they will align themselves perpendicular to the maximum stress direction. For clay mineral and fine-grained micas, the planar fabric that results is referred to as a slaty cleavage ...
... maintained for a long period of time, minerals will tend to increase in size. • Foliation - As new platy minerals grow, they will align themselves perpendicular to the maximum stress direction. For clay mineral and fine-grained micas, the planar fabric that results is referred to as a slaty cleavage ...
Geophysical and Geochemical Approaches
... Introduction: The presence of a broad zone of exhumed mantle at the West Iberia rifted margin is now well documented (e.g., Whitmarsh et al., 2001), but it remains unclear how widespread such margins are. The UK western approaches margin at Goban Spur (Figure 1) represents another generally amagmati ...
... Introduction: The presence of a broad zone of exhumed mantle at the West Iberia rifted margin is now well documented (e.g., Whitmarsh et al., 2001), but it remains unclear how widespread such margins are. The UK western approaches margin at Goban Spur (Figure 1) represents another generally amagmati ...
Lecture 6 - Mantle and Basalts
... E-MORB’s are represented by plumes centered on mid-ocean ridges. Examples include Iceland and the Azores. They are thought to be derived from plumes generated near the 650 km discontinuity, from either a) a distinct lower mantle source, or b) boundary source enriched by subducted ocean crust trapp ...
... E-MORB’s are represented by plumes centered on mid-ocean ridges. Examples include Iceland and the Azores. They are thought to be derived from plumes generated near the 650 km discontinuity, from either a) a distinct lower mantle source, or b) boundary source enriched by subducted ocean crust trapp ...
Petrology Lecture 8
... • μ = 238U/204Pb, and is used to evaluate uranium enrichment • The HIMU reservoir is quite distinctive in the Pb system, having a very high 206Pb/204Pb ratio, suggestive of a source with high U, yet not enriched in Rb, and old enough (> 1 Ga) to develop the observed isotopic ratios by radioactive de ...
... • μ = 238U/204Pb, and is used to evaluate uranium enrichment • The HIMU reservoir is quite distinctive in the Pb system, having a very high 206Pb/204Pb ratio, suggestive of a source with high U, yet not enriched in Rb, and old enough (> 1 Ga) to develop the observed isotopic ratios by radioactive de ...
Exercises in basic isostasy
... 1a. Use the principle of Airy isostasy to determine the elevation of a mountain range, where the crustal thickness is 65 km, relative to a reference region where the crust is 35 km thick. Assume a simple 2-layer model with constant density crust, ρc = 2.8 x 103 kg m-3 overlying constant density mant ...
... 1a. Use the principle of Airy isostasy to determine the elevation of a mountain range, where the crustal thickness is 65 km, relative to a reference region where the crust is 35 km thick. Assume a simple 2-layer model with constant density crust, ρc = 2.8 x 103 kg m-3 overlying constant density mant ...
Petrogenesis of subvolcanic rocks from the Khunik prospecting area
... a b s t r a c t The Khunik prospecting area is located 106 km south of Birjand in eastern Iran, and is considered as an epithermal gold prospecting area. The mineralization is related to subvolcanic rocks. There are several outcrops of subvolcanic intrusions in the area which intruded into Paleocene ...
... a b s t r a c t The Khunik prospecting area is located 106 km south of Birjand in eastern Iran, and is considered as an epithermal gold prospecting area. The mineralization is related to subvolcanic rocks. There are several outcrops of subvolcanic intrusions in the area which intruded into Paleocene ...
Modification of the Continental Crust by Subduction Zone
... formed by long-term subduction of oceanic lithosphere beneath continental lithosphere. The central Andes, in particular, represent the type locality for this process owing to the great width of the orogen and immense crustal thicknesses (up to 70–80 km; [29]) and high elevations (~4–6 km; [50]) that ...
... formed by long-term subduction of oceanic lithosphere beneath continental lithosphere. The central Andes, in particular, represent the type locality for this process owing to the great width of the orogen and immense crustal thicknesses (up to 70–80 km; [29]) and high elevations (~4–6 km; [50]) that ...
Modification of the Continental Crust by Subduction Zone
... formed by long-term subduction of oceanic lithosphere beneath continental lithosphere. The central Andes, in particular, represent the type locality for this process owing to the great width of the orogen and immense crustal thicknesses (up to 70–80 km; [29]) and high elevations (~4–6 km; [50]) that ...
... formed by long-term subduction of oceanic lithosphere beneath continental lithosphere. The central Andes, in particular, represent the type locality for this process owing to the great width of the orogen and immense crustal thicknesses (up to 70–80 km; [29]) and high elevations (~4–6 km; [50]) that ...
The tonalite–trondhjemite–granodiorite (TTG)
... and high-K granodiorite–granite (GG) rocks. Both types of granitoids were intruded contemporaneously, although TTGs are more abundant in the older gneisses. The TTG suite consists of calcic to marginally calc-alkalic rocks that straddle the boundaries between metaluminous and peraluminous and betwee ...
... and high-K granodiorite–granite (GG) rocks. Both types of granitoids were intruded contemporaneously, although TTGs are more abundant in the older gneisses. The TTG suite consists of calcic to marginally calc-alkalic rocks that straddle the boundaries between metaluminous and peraluminous and betwee ...
Neogene-Recent rifting and volcanism in northern Tanzania
... The magmatic rocks of the Gardar province were emplaced mainly in the Ketilidian circum-cratonic orogen close to its contact with the Greenland segment of the North Atlantic Craton (Winchester, 1988). The dykes, lavas and central complexes, with an areal extent of approximately 80 km from north to s ...
... The magmatic rocks of the Gardar province were emplaced mainly in the Ketilidian circum-cratonic orogen close to its contact with the Greenland segment of the North Atlantic Craton (Winchester, 1988). The dykes, lavas and central complexes, with an areal extent of approximately 80 km from north to s ...
Lithostratigraphy
... Hiatus- when strata were removed after deposition (degradational vacuity). ...
... Hiatus- when strata were removed after deposition (degradational vacuity). ...
Slide 1
... LREE enriched rare earth element patterns where REE abundances increase with increasing SiO2. The second compositional group (Type II) shows trends of LREE enrichment and HREE depletion, where both LREE and HREE abundances decrease with increasing SiO2. They are also depleted in Y and enriched in Sr ...
... LREE enriched rare earth element patterns where REE abundances increase with increasing SiO2. The second compositional group (Type II) shows trends of LREE enrichment and HREE depletion, where both LREE and HREE abundances decrease with increasing SiO2. They are also depleted in Y and enriched in Sr ...
50 PLATE TECTONICS I. Introduction A. General 1. The theory of
... The theory of Plate Tectonics now recognizes that the positions of land masses are not fixed and that they have moved about the earth's surface over geologic history a. ...
... The theory of Plate Tectonics now recognizes that the positions of land masses are not fixed and that they have moved about the earth's surface over geologic history a. ...
Plate_tectonics_Ss_2014
... of cool, solid rock 20 to 60 km thick, these enormous blocks of Earth’s crust vary in size and shape, and have definite borders that cut through continents and oceans alike. Oceanic crust is much thinner (about 5 km) and denser than continental or terrestrial crust. There are nine large plates and a ...
... of cool, solid rock 20 to 60 km thick, these enormous blocks of Earth’s crust vary in size and shape, and have definite borders that cut through continents and oceans alike. Oceanic crust is much thinner (about 5 km) and denser than continental or terrestrial crust. There are nine large plates and a ...
Plate Tectonics Wholly, completely
... of cool, solid rock 20 to 60 km thick, these enormous blocks of Earth’s crust vary in size and shape, and have definite borders that cut through continents and oceans alike. Oceanic crust is much thinner (about 5 km) and denser than continental or terrestrial crust. There are nine large plates and a ...
... of cool, solid rock 20 to 60 km thick, these enormous blocks of Earth’s crust vary in size and shape, and have definite borders that cut through continents and oceans alike. Oceanic crust is much thinner (about 5 km) and denser than continental or terrestrial crust. There are nine large plates and a ...
Tectonic reconstruction of Uda-Murgal arc and the Late
... The eastern margin of Northeastern Eurasia records a long history of subduction and terrane accretion through preservation of volcanic arc assemblages, exotic terranes and fold belts reflecting collision. Prominent volcanic arcs are the present activity in Kamchatka and the Late Albian to late Creta ...
... The eastern margin of Northeastern Eurasia records a long history of subduction and terrane accretion through preservation of volcanic arc assemblages, exotic terranes and fold belts reflecting collision. Prominent volcanic arcs are the present activity in Kamchatka and the Late Albian to late Creta ...
12.002 Physics and Chemistry of the Earth and Terrestrial Planets
... beneath adjacent areas that are at sea-level are 2800 km/m3 and 35 km respectively (and that the density and thickness of the lithospheric mantle beneath the two areas is the same). b) Assume that instead of Airy-compensation you have Pratt compensation, so that the crust is only 40 km thick with a ...
... beneath adjacent areas that are at sea-level are 2800 km/m3 and 35 km respectively (and that the density and thickness of the lithospheric mantle beneath the two areas is the same). b) Assume that instead of Airy-compensation you have Pratt compensation, so that the crust is only 40 km thick with a ...
TECTONIC AND GEOLOGIC EVOLUTION OF THAILAND
... northern side from Shan-Thai to Turkey, and the long strip of continent on the north side of the rift was left behind. The rift opened to form a new ocean, the Incipient Mesozoic Tethys. Subsequently the Paleozoic Tethys {Paleotethys) closed along consuming plate margins along its northern side. Clo ...
... northern side from Shan-Thai to Turkey, and the long strip of continent on the north side of the rift was left behind. The rift opened to form a new ocean, the Incipient Mesozoic Tethys. Subsequently the Paleozoic Tethys {Paleotethys) closed along consuming plate margins along its northern side. Clo ...
geologic map (scale 1 :250000) of the penokean orogen, central
... has been flown (Chandler, 1983a, b, c, 1985), and computer-prepared derivative maps and theoretical models based on the aeromagnetic data (Carlson, 1985) have extended the utility of the survey beyond qualitative interpretation. The process of converting the aeromagnetic data into a geologic map has ...
... has been flown (Chandler, 1983a, b, c, 1985), and computer-prepared derivative maps and theoretical models based on the aeromagnetic data (Carlson, 1985) have extended the utility of the survey beyond qualitative interpretation. The process of converting the aeromagnetic data into a geologic map has ...
Lecture 25
... OIB (yellow line) shown for comparison Figure 16-11a. MORB-normalized spider diagrams for selected island arc basalts. Using the normalization and ordering scheme of Pearce (1983) with LIL on the left and HFS on the right and compatibility increasing outward from Ba-Th. Data from BVTP. Composite OIB ...
... OIB (yellow line) shown for comparison Figure 16-11a. MORB-normalized spider diagrams for selected island arc basalts. Using the normalization and ordering scheme of Pearce (1983) with LIL on the left and HFS on the right and compatibility increasing outward from Ba-Th. Data from BVTP. Composite OIB ...
The stratigraphic succession of Ghana
... themselves deformed in the waning phases of the Eburnian event. The evidence that most granite emplacement was over by the time the Tarkwaian sediments in Ghana were deposited is certainly consistent with this interpretation. Whether or not the subdivision into Eburnian I and II events can be justif ...
... themselves deformed in the waning phases of the Eburnian event. The evidence that most granite emplacement was over by the time the Tarkwaian sediments in Ghana were deposited is certainly consistent with this interpretation. Whether or not the subdivision into Eburnian I and II events can be justif ...
Structural Geology, Holloway Mine, Abitibi
... identified and described those structures associated with the PDDZ in order to shed new light on its place within the larger tectonic history of the Abitibi greenstone belt. Work began in the summer of 1997 and continued through the summer of 1998, with additional work completed in the summer of 199 ...
... identified and described those structures associated with the PDDZ in order to shed new light on its place within the larger tectonic history of the Abitibi greenstone belt. Work began in the summer of 1997 and continued through the summer of 1998, with additional work completed in the summer of 199 ...
Alfred Wegener's Theory of Continental Drift Became Modern Plate
... One basic rule of geological processes is that the newest rock is on the top and the rocks get older layer by layer toward the bottom. The top layers are not identical because a lot has happened in the 80 million years they have been separated. ...
... One basic rule of geological processes is that the newest rock is on the top and the rocks get older layer by layer toward the bottom. The top layers are not identical because a lot has happened in the 80 million years they have been separated. ...
Lecture #10 -- Magma types and types of eruptions (text pages 151
... by perturbations of the earth’s mantle and lower crust due to plate tectonics. The outer core of the earth is liquid iron, but magmas are rock, not iron, and the outer core is too deep to be tapped by volcanism Magmas are generated in 3 different tectonic environments. The main two (figure 1) are: ...
... by perturbations of the earth’s mantle and lower crust due to plate tectonics. The outer core of the earth is liquid iron, but magmas are rock, not iron, and the outer core is too deep to be tapped by volcanism Magmas are generated in 3 different tectonic environments. The main two (figure 1) are: ...
Homework 5: Buoyancy Introduction The buoyancy of plates is a
... from 15-60 km. This will allow you to determine the range of conditions under which continents can be subducted. 5. Is it possible to get continental lithosphere with normal crust (30 km thick) and normal plate thickness (200 km) to subduct if it is attached to a length of subducting oceanic lithosp ...
... from 15-60 km. This will allow you to determine the range of conditions under which continents can be subducted. 5. Is it possible to get continental lithosphere with normal crust (30 km thick) and normal plate thickness (200 km) to subduct if it is attached to a length of subducting oceanic lithosp ...
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.