RELICT PLAGIOCLASE PHENOCRYSTS FROM AMPHIBO_ LITE
... position of the twin plane is controlled by the composition of the crystal as well as the structural state. A small but consisient internal scatter in sample r1-gN may indicate that the reorientation in this sample is not comprete. Zoning is present in a thin area adjacent to the composition pranes ...
... position of the twin plane is controlled by the composition of the crystal as well as the structural state. A small but consisient internal scatter in sample r1-gN may indicate that the reorientation in this sample is not comprete. Zoning is present in a thin area adjacent to the composition pranes ...
Density constraints on the formation of the continental Moho and crust
... mind, we think that the obducted portions of the upper and lower crustal columns reviewed by Fountain and Salisbury (1981) point to the overall importance of a magma underplating model. Common to the cross-sections at the Invrea Zone, Fraser and Musgrave Range, Pikwitonei Belt, and the Kasila Series ...
... mind, we think that the obducted portions of the upper and lower crustal columns reviewed by Fountain and Salisbury (1981) point to the overall importance of a magma underplating model. Common to the cross-sections at the Invrea Zone, Fraser and Musgrave Range, Pikwitonei Belt, and the Kasila Series ...
The California Arc: Thick Granitic Batholiths, Eclogitic Residues
... proportions of mantle versus crustal components in the arc (Miller et al., 1988), but help identify qualitatively three important end members that contribute to the isotopic heterogeneity of the batholith. These end members (S is sedimentary, C is old lower crustal, and M is young mantle [Fig. 4]) a ...
... proportions of mantle versus crustal components in the arc (Miller et al., 1988), but help identify qualitatively three important end members that contribute to the isotopic heterogeneity of the batholith. These end members (S is sedimentary, C is old lower crustal, and M is young mantle [Fig. 4]) a ...
Modern Plate Tectonics
... Structure of the Earth The Earth can be considered as being made up of a series of concentric spheres, each made up of materials that differ in terms of composition and mechanical properties. ...
... Structure of the Earth The Earth can be considered as being made up of a series of concentric spheres, each made up of materials that differ in terms of composition and mechanical properties. ...
Lesson: Rock Cycle-Focus on Igneous Rocks
... This lesson introduces the students to the igneous rocks and the rock cycle and for students to learn how to identify an igneous rock based on its observable properties. Igneous rock formation is important to understand as it relates to the dynamically changing geosphere through plate tectonics, vol ...
... This lesson introduces the students to the igneous rocks and the rock cycle and for students to learn how to identify an igneous rock based on its observable properties. Igneous rock formation is important to understand as it relates to the dynamically changing geosphere through plate tectonics, vol ...
doc
... This lesson introduces the students to the igneous rocks and the rock cycle and for students to learn how to identify an igneous rock based on its observable properties. Igneous rock formation is important to understand as it relates to the dynamically changing geosphere through plate tectonics, vol ...
... This lesson introduces the students to the igneous rocks and the rock cycle and for students to learn how to identify an igneous rock based on its observable properties. Igneous rock formation is important to understand as it relates to the dynamically changing geosphere through plate tectonics, vol ...
Modern Plate Tectonics
... The Core: the metallic portion of the Earth; Iron mixed with small amounts of Nickel. Outer Core: probably liquid (based on studies of shock wave passage through the Earth). Inner Core: solid, made up of cooled liquid core material. ...
... The Core: the metallic portion of the Earth; Iron mixed with small amounts of Nickel. Outer Core: probably liquid (based on studies of shock wave passage through the Earth). Inner Core: solid, made up of cooled liquid core material. ...
Proto-Oceanic Crust in the North and South Atlantic
... of rifted margins combined with a lack of understanding of the initial “fit” and opening geometries of these margins. As the search for hydrocarbons moves into deep and ultra-deep areas, there is an economic need to better-constrain the architecture of conjugate margins. Several projects (PROBE, SAM ...
... of rifted margins combined with a lack of understanding of the initial “fit” and opening geometries of these margins. As the search for hydrocarbons moves into deep and ultra-deep areas, there is an economic need to better-constrain the architecture of conjugate margins. Several projects (PROBE, SAM ...
Gravity and density variations of the tilted Tottabetsu plutonic complex,
... the map pattern of the complex, implying that the complex presently has steeply dipping sides. Paleohorizontals inferred from magmatic structures (see below) roughly strike N-S and dip steeply eastward in the range between 50◦ and 90◦ (Fig. 1(a)). On the basis of the dips of the paleohorizontals and ...
... the map pattern of the complex, implying that the complex presently has steeply dipping sides. Paleohorizontals inferred from magmatic structures (see below) roughly strike N-S and dip steeply eastward in the range between 50◦ and 90◦ (Fig. 1(a)). On the basis of the dips of the paleohorizontals and ...
PDF format - gemoc - Macquarie University
... grains enclosed in concentrate-derived minerals from the Lac de Gras area, Slave craton, by electron microprobe, quadrupole laser ablation microprobe (LAM) ICPMS and multicollector LAM ICPMS, respectively. The in-situ method for the collection of Re-Os isotope data from individual sulfides removes m ...
... grains enclosed in concentrate-derived minerals from the Lac de Gras area, Slave craton, by electron microprobe, quadrupole laser ablation microprobe (LAM) ICPMS and multicollector LAM ICPMS, respectively. The in-situ method for the collection of Re-Os isotope data from individual sulfides removes m ...
Evidence and implications for a widespread magmatic shutdown for
... Pietranik et al., 2008; Wang et al., 2009). As with global granitoid ages, juvenile granitoids exhibit an age gap between about 2.45 and 2.2 Ga. Although the Arrowsmith orogen in western Canada (2.4–2.3 Ga) may be an ancient convergent margin, largely negative εNd(T) values from granitoids in this o ...
... Pietranik et al., 2008; Wang et al., 2009). As with global granitoid ages, juvenile granitoids exhibit an age gap between about 2.45 and 2.2 Ga. Although the Arrowsmith orogen in western Canada (2.4–2.3 Ga) may be an ancient convergent margin, largely negative εNd(T) values from granitoids in this o ...
ALKALINE PORPHYRY COPPER DEPOSITS AND - Rigeo
... and IOCG deposits are much more profound resulting from several different characteristics in: i) the geotectonic settings (subduction versus intracratonic); ii) the magma’s chemical composition (calk-alkaline or mildly alkaline versus MMM mantellic-metasomatic-magmas, Mitchell 1995) and migration dy ...
... and IOCG deposits are much more profound resulting from several different characteristics in: i) the geotectonic settings (subduction versus intracratonic); ii) the magma’s chemical composition (calk-alkaline or mildly alkaline versus MMM mantellic-metasomatic-magmas, Mitchell 1995) and migration dy ...
GE 11a Homework 4: Isostacy and the Geographic
... (4) Consider a block of continental crust that is initially 50 km thick and 300 km wide (its third dimension can be neglected). This block thickens homogeneously in response to shortening driven by tectonic convergence on its edges, with no change in the block’s total volume. Given a rate of shorten ...
... (4) Consider a block of continental crust that is initially 50 km thick and 300 km wide (its third dimension can be neglected). This block thickens homogeneously in response to shortening driven by tectonic convergence on its edges, with no change in the block’s total volume. Given a rate of shorten ...
pdf
... magmatic activity. Subsequent to initial alkaline magmatism, localized mid-oceanic ridge basalts (MORB) magmatism was again replaced by basin-wide alkaline events, caused by a low degree of decompression melting due to tectonic delocalization of deformation. Such “off-axis” magmatism might be a comm ...
... magmatic activity. Subsequent to initial alkaline magmatism, localized mid-oceanic ridge basalts (MORB) magmatism was again replaced by basin-wide alkaline events, caused by a low degree of decompression melting due to tectonic delocalization of deformation. Such “off-axis” magmatism might be a comm ...
ppt - nsf margins
... represent the nucleus of continents, yet there is no clear consensus on how these rocks originate. The Jurassic Talkeetna island arc in south-central Alaska is an exhumed and titled arc section where middle and upper crust lithologies are now exposed at the surface, providing us with the rare opport ...
... represent the nucleus of continents, yet there is no clear consensus on how these rocks originate. The Jurassic Talkeetna island arc in south-central Alaska is an exhumed and titled arc section where middle and upper crust lithologies are now exposed at the surface, providing us with the rare opport ...
TheCase
... the name, Baja British Columbia. However, views about tectonic evolution of western North America as well as concerns over reliability of the paleomagnetic data had the geologic community up in arms. _______________________________________ The Background Information: Paleomagnetism: The basic idea o ...
... the name, Baja British Columbia. However, views about tectonic evolution of western North America as well as concerns over reliability of the paleomagnetic data had the geologic community up in arms. _______________________________________ The Background Information: Paleomagnetism: The basic idea o ...
Kelsey Beechler ERTH 201 Lab East African Rift Valley Rift valleys
... mountainous and dry region. When the earth was in the single continental mass called Pangaea, the climate of the earth was very extreme. The oceans had massive storms and the land had intense temperatures. The inland of the Pangaea continent was extremely dry due to the lack of an oceanic coast or m ...
... mountainous and dry region. When the earth was in the single continental mass called Pangaea, the climate of the earth was very extreme. The oceans had massive storms and the land had intense temperatures. The inland of the Pangaea continent was extremely dry due to the lack of an oceanic coast or m ...
BH O`Brien - Department of Natural Resources
... have been projected up-dip and southeastward into the plane of the Figure 2 cross-section. The vertical section shown in Figure 2 approximates to a longitudinal view of Roberts Arm strata that were previously depicted in several northwest–southeast sections of the southeast margin of the Roberts Arm ...
... have been projected up-dip and southeastward into the plane of the Figure 2 cross-section. The vertical section shown in Figure 2 approximates to a longitudinal view of Roberts Arm strata that were previously depicted in several northwest–southeast sections of the southeast margin of the Roberts Arm ...
GEO 112, Spring 2008 Laboratory exercise #1
... sediments deposited in a floodplain environment. What is the average rate of sediment deposition for the unit sampled by rocks A and B? Give units _0.00225 m/year or 2.25 mm/year_ What is the average rate of sediment deposition for the unit sampled by rocks C and D? Give units _0.00125 m/year or 1.2 ...
... sediments deposited in a floodplain environment. What is the average rate of sediment deposition for the unit sampled by rocks A and B? Give units _0.00225 m/year or 2.25 mm/year_ What is the average rate of sediment deposition for the unit sampled by rocks C and D? Give units _0.00125 m/year or 1.2 ...
Summary of Research Projects John W. Shervais Department of Geology Professor and Head
... An alternative approach is to examine outcrops of lithospheric mantle that underlie crust known to have formed by supra-subduction zone (SSZ) magmatism. This lithospheric mantle represents in part the source from which the overlying crust was extracted, and its mineralogy and composition reflect the ...
... An alternative approach is to examine outcrops of lithospheric mantle that underlie crust known to have formed by supra-subduction zone (SSZ) magmatism. This lithospheric mantle represents in part the source from which the overlying crust was extracted, and its mineralogy and composition reflect the ...
29. Sr-, Nd-, AND Pb-ISOTOPIC COMPOSITION OF VOLCANIC
... 1994) and these informal sample numbers are keyed to full ODP designations in Table 1. The isotopic data are reported in Table 2; chemical analyses of the same samples are given in Fitton et al. (this volume). Variation of 87Sr/86Sr and 143Nd/144Nd in volcanic rocks from the Leg 152 transect is show ...
... 1994) and these informal sample numbers are keyed to full ODP designations in Table 1. The isotopic data are reported in Table 2; chemical analyses of the same samples are given in Fitton et al. (this volume). Variation of 87Sr/86Sr and 143Nd/144Nd in volcanic rocks from the Leg 152 transect is show ...
the atacama fault system in the huasco province
... Paposo and the El Salado segments (Naranjo, 1987). In the last 10 years systematic studies of the northern-most segments have produced considerable progress on the understanding of the chronology and flow regime of the displacements associated with the activity of the AFS (Brown et al., 1993; Dallme ...
... Paposo and the El Salado segments (Naranjo, 1987). In the last 10 years systematic studies of the northern-most segments have produced considerable progress on the understanding of the chronology and flow regime of the displacements associated with the activity of the AFS (Brown et al., 1993; Dallme ...
SXR339 Ancient Mountains ISBN0749258470
... and a sheeted dyke complex. The upper nappe is composed of peridotites. The occurrence of ophiolitic nappes in thrust contact with Dalradian metasediments suggests that the oceanic crust had been tectonically emplaced by thrusting onto the continental crust – a process called obduction. The position ...
... and a sheeted dyke complex. The upper nappe is composed of peridotites. The occurrence of ophiolitic nappes in thrust contact with Dalradian metasediments suggests that the oceanic crust had been tectonically emplaced by thrusting onto the continental crust – a process called obduction. The position ...
Nevado de Longaví Volcano (Chilean Andes, 36.2 ˚S): adakitic
... unusually high B (19-55 ppm), are consistent with important slab-derived fluid contributions. The NLV adakitic dacites have high Sr (∼590 ppm) and Sr/Y (∼70), indicative of suppression of plagioclase crystallization combined with the fractionation of phases for which Y and HREE are compatible. This ...
... unusually high B (19-55 ppm), are consistent with important slab-derived fluid contributions. The NLV adakitic dacites have high Sr (∼590 ppm) and Sr/Y (∼70), indicative of suppression of plagioclase crystallization combined with the fractionation of phases for which Y and HREE are compatible. This ...
Chapter 9
... • Archean crust-forming processes generated – granite-gneiss complexes – and greenstone belts – that were shaped into cratons ...
... • Archean crust-forming processes generated – granite-gneiss complexes – and greenstone belts – that were shaped into cratons ...
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.