Transfer of melts in the sub-arc mantle: Insights from high
... 4.2.1. General historical introduction of New Caledonia New Caledonia is an archipelago in the south-west Pacific Ocean composed of several islands (Loyalty Is., Belep Is., Ile des Pins, Ile Ouen, Grande Terre), reefs and lagoons which are a territorial collectivity of France. The archipelago lies a ...
... 4.2.1. General historical introduction of New Caledonia New Caledonia is an archipelago in the south-west Pacific Ocean composed of several islands (Loyalty Is., Belep Is., Ile des Pins, Ile Ouen, Grande Terre), reefs and lagoons which are a territorial collectivity of France. The archipelago lies a ...
the Scanned PDF
... allied rocks of Iki Island, Japan. These inclusions are divided into two groups: (1) spinelbearing wehrlite, pyroxenite and gabbro, and (2) magnetite-bearing gabbro and anorthosite. The first group is characterized by pyroxene-spinel symplectites produced by reaction between olivine and plagioclase. ...
... allied rocks of Iki Island, Japan. These inclusions are divided into two groups: (1) spinelbearing wehrlite, pyroxenite and gabbro, and (2) magnetite-bearing gabbro and anorthosite. The first group is characterized by pyroxene-spinel symplectites produced by reaction between olivine and plagioclase. ...
Insights into extensional processes during magma assisted rifting
... rift floor and are typically located at the intersection of east–west striking faults with the more dominant northeast–southwest striking faulting in the rift (Korme et al., 2004; Abebe et al., 2007). The origin of these silicic centres has been linked to variations in strain rate, where the transiti ...
... rift floor and are typically located at the intersection of east–west striking faults with the more dominant northeast–southwest striking faulting in the rift (Korme et al., 2004; Abebe et al., 2007). The origin of these silicic centres has been linked to variations in strain rate, where the transiti ...
Geologic Structures
... The hypothesis given here is based on calculations about the behavior of dust and gas in space and on observations of stars and dust clouds in our galaxy. Refer to the “Focus On” box on page 12 for a discussion of how scientists formulate a hypothesis. The hypothesis states that about 5 billion year ...
... The hypothesis given here is based on calculations about the behavior of dust and gas in space and on observations of stars and dust clouds in our galaxy. Refer to the “Focus On” box on page 12 for a discussion of how scientists formulate a hypothesis. The hypothesis states that about 5 billion year ...
NORSK GEOLOGISK TIDSSKRIFT 45 DISTRIBUTION PATTERNS
... 3. Any failure of the REE to act coherently may be attributed to: a) differences in ionic radius (the radius decreases from La to Lu), b) differences in basicity (the basicity decreases from La to Lu), or c) ability of a number of REE to exist in an oxidation state other than +3 (i.e. Ce-+4, Sm+2, E ...
... 3. Any failure of the REE to act coherently may be attributed to: a) differences in ionic radius (the radius decreases from La to Lu), b) differences in basicity (the basicity decreases from La to Lu), or c) ability of a number of REE to exist in an oxidation state other than +3 (i.e. Ce-+4, Sm+2, E ...
Minerals and Rocks - The University Digital Library
... rises towards the surface because it has a lower density than the surrounding mantle rocks. If the magma reaches the surface, a volcano is formed. Magma at the surface of the earth is called lava. Volcanic eruptions can produce mainly lava, but some eruptions are explosive and produce large volumes ...
... rises towards the surface because it has a lower density than the surrounding mantle rocks. If the magma reaches the surface, a volcano is formed. Magma at the surface of the earth is called lava. Volcanic eruptions can produce mainly lava, but some eruptions are explosive and produce large volumes ...
Shervais, J.W., 2001, Birth, Death, and Resurrection: The Life Cycle
... [1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation ...
... [1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation ...
The life cycle of suprasubduction zone ophiolites
... [1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation ...
... [1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation ...
The track of the Yellowstone hot spot
... K. L. Pierce and L. A. Morgan No continental analogues similar to Yellowstone eastern Snake River Plain are known to us for a hot spot/mantle plume. The following special characteristics of the North American plate and the western United States are probably important in how the Yellowstone hot spot ...
... K. L. Pierce and L. A. Morgan No continental analogues similar to Yellowstone eastern Snake River Plain are known to us for a hot spot/mantle plume. The following special characteristics of the North American plate and the western United States are probably important in how the Yellowstone hot spot ...
Influence of continental roots and asthenosphere on plate
... decreasing tractions near ridges where lithosphere thickness is small and increasing them by a factor of 2 to 5 for deeply penetrating cratons. When averaged globally, we see that the fractional change in traction magnitude increases monotonically with lithospheric thickness (red line, Figure 4). Fo ...
... decreasing tractions near ridges where lithosphere thickness is small and increasing them by a factor of 2 to 5 for deeply penetrating cratons. When averaged globally, we see that the fractional change in traction magnitude increases monotonically with lithospheric thickness (red line, Figure 4). Fo ...
Lecture 19: Mantle Plumes - Earth and Atmospheric Sciences
... depleted. eNd values of +500 have been recorded in garnets in eclogites from the Roberts Victor mine kimberlite. These eclogites appear to be rafts of subducted oceanic crust stranded in the subcontinental lithosphere over 3 Ga ago, an interpretation supported by highly variable oxygen isotope ratio ...
... depleted. eNd values of +500 have been recorded in garnets in eclogites from the Roberts Victor mine kimberlite. These eclogites appear to be rafts of subducted oceanic crust stranded in the subcontinental lithosphere over 3 Ga ago, an interpretation supported by highly variable oxygen isotope ratio ...
Plume mantle source heterogeneity through time: Insights from the
... opportunity to study an on-land fragment of the Caribbean-Colombian oceanic plateau. Geochemical, Sr-Nd isotope, and 40Ar-39Ar radiometric age data combined with detailed mapping have shown that the Duarte Complex includes two lithostratigraphic units, composed of four geochemical groups of metavolc ...
... opportunity to study an on-land fragment of the Caribbean-Colombian oceanic plateau. Geochemical, Sr-Nd isotope, and 40Ar-39Ar radiometric age data combined with detailed mapping have shown that the Duarte Complex includes two lithostratigraphic units, composed of four geochemical groups of metavolc ...
Kurzlaukis and Lorenz_Gibeon Volcanic Field
... Signs of multiple intrusive activity within the kimberlite dikes have not been recognised. This is probably due to poor outcrop quality and the high degree of alteration of most of the kimberlites. The only exception is the carbonatitic dike near Mukorob, which shows vertical planar zonation. The in ...
... Signs of multiple intrusive activity within the kimberlite dikes have not been recognised. This is probably due to poor outcrop quality and the high degree of alteration of most of the kimberlites. The only exception is the carbonatitic dike near Mukorob, which shows vertical planar zonation. The in ...
mantle plumes and hot spots - The Centre for Earth Evolution and
... Ridge, up to several kilometres high. These tracks are thought to form as lithospheric plates move over plumes. The active hotspot is at one end of the chain; radiometric dating has determined that the ages of the volcanics along the chain tend to increase with distance from the active hotspot. Inte ...
... Ridge, up to several kilometres high. These tracks are thought to form as lithospheric plates move over plumes. The active hotspot is at one end of the chain; radiometric dating has determined that the ages of the volcanics along the chain tend to increase with distance from the active hotspot. Inte ...
as a PDF
... Horizontal rock slices were cut from the field-oriented specimens. Oriented thin sections were made from the slices, which were photographed and mounted between hemispheres on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains ...
... Horizontal rock slices were cut from the field-oriented specimens. Oriented thin sections were made from the slices, which were photographed and mounted between hemispheres on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains ...
A Geochemical Study of Crustal Plutonic Rocks from the Southern
... shows that the plutonic suites formed via melting of boninite crust or by crystallization from a boninite-like magma rather than other sources that are found in the IBM system. The data presented support the hypothesis that the plutonic rocks from RD63 and RD64 are products of subduction initiation ...
... shows that the plutonic suites formed via melting of boninite crust or by crystallization from a boninite-like magma rather than other sources that are found in the IBM system. The data presented support the hypothesis that the plutonic rocks from RD63 and RD64 are products of subduction initiation ...
Tectonostratigraphic Terranes and Tectonic Evolution of Mexico
... was controlled by left-oblique convergence of Mexico with plates in the Pacific basin. (8) Paleomagnetic data that indicate about 15° of northward latitudinal displacement of Baja in the Late Cretaceous and Paleogene can be reconciled with geologic correlations only by postulating an earlier episode ...
... was controlled by left-oblique convergence of Mexico with plates in the Pacific basin. (8) Paleomagnetic data that indicate about 15° of northward latitudinal displacement of Baja in the Late Cretaceous and Paleogene can be reconciled with geologic correlations only by postulating an earlier episode ...
Mesozoic tectonics of the Maria fold and thrust belt and McCoy basin
... and McCoy Basin tectonic provinces of southeastern California. We also present new geologic mapping, structural analysis from macroscopic to microscopic scale, U-Pb zircon ages and Ar-Ar hornblende and biotite ages from key areas in the Maria Fold and Thrust Belt and McCoy Basin to resolve kinematic ...
... and McCoy Basin tectonic provinces of southeastern California. We also present new geologic mapping, structural analysis from macroscopic to microscopic scale, U-Pb zircon ages and Ar-Ar hornblende and biotite ages from key areas in the Maria Fold and Thrust Belt and McCoy Basin to resolve kinematic ...
PRESIDENTIAL ADDRESS Patterns of mineral
... occurred with the emplacement of the Devonian Onawa granodiorite at P ª 3000 bars and T up to ª650 °C (Symmes and Ferry 1995). At the lowest grades of metamorphism, all pelites contain Mnz that is distinctive both for its patchy chemical zoning (chiefly in ThO2 content) and its irregular habit. This ...
... occurred with the emplacement of the Devonian Onawa granodiorite at P ª 3000 bars and T up to ª650 °C (Symmes and Ferry 1995). At the lowest grades of metamorphism, all pelites contain Mnz that is distinctive both for its patchy chemical zoning (chiefly in ThO2 content) and its irregular habit. This ...
OKINAWA TROUGH: ORIGIN OF A BACK
... Lee, C-S., Shor, G.G. Jr., Bibee, L.D., Lee, R.S. and Hilde, T.W.C., 1980. Okinawa Trough: origin of a back-arc basin. Mar. Geol., 35: 219--241. The sequence of back-arc basin development in the southwestern part of Okinawa Trough has apparently been crustal thinning, involving normal faulting and f ...
... Lee, C-S., Shor, G.G. Jr., Bibee, L.D., Lee, R.S. and Hilde, T.W.C., 1980. Okinawa Trough: origin of a back-arc basin. Mar. Geol., 35: 219--241. The sequence of back-arc basin development in the southwestern part of Okinawa Trough has apparently been crustal thinning, involving normal faulting and f ...
Subcontinental Lithosphere
... depleted. εNd values of +500 have been recorded in garnets in eclogites from the Roberts Victor mine kimberlite. These eclogites appear to be rafts of subducted oceanic crust stranded in the subcontinental lithosphere over 3 Ga ago, an interpretation supported by highly variable oxygen isotope ratio ...
... depleted. εNd values of +500 have been recorded in garnets in eclogites from the Roberts Victor mine kimberlite. These eclogites appear to be rafts of subducted oceanic crust stranded in the subcontinental lithosphere over 3 Ga ago, an interpretation supported by highly variable oxygen isotope ratio ...
The nature of the crust beneath the Afar triple junction: Evidence
... spreading center in northern Afar. The crust beneath Afar has a thickness of 20–26 km outside the currently active rift segments and thins northward. It is bounded by thick crust beneath the highlands of the western plateau (∼40 km) and southeastern plateau (∼35 km). The western plateau shows VP/VS ...
... spreading center in northern Afar. The crust beneath Afar has a thickness of 20–26 km outside the currently active rift segments and thins northward. It is bounded by thick crust beneath the highlands of the western plateau (∼40 km) and southeastern plateau (∼35 km). The western plateau shows VP/VS ...
Large igneous provinces and mass extinctions: An update
... during 1783–1784. Another link between volcanism and cooling was seen during one of the largest episodes of volcanic stratospheric H2SO4 loading of the past 500 yr from Huaynaputina, in Peru, which erupted in 1600 coincident with the coldest global average temperatures of the time (de Silva and Ziel ...
... during 1783–1784. Another link between volcanism and cooling was seen during one of the largest episodes of volcanic stratospheric H2SO4 loading of the past 500 yr from Huaynaputina, in Peru, which erupted in 1600 coincident with the coldest global average temperatures of the time (de Silva and Ziel ...
Aquatic biomes
... • large, natural bodies of standing fresh water • formed when precipitation, runoff, groundwater seepage fills depressions in earth’s surface – depressions can be formed by » glaciation (Great Lakes, NA) » crustal displacement (Lake Nyasa, East Africa) » volcanic activity (Crater Lake, Oregon) • lar ...
... • large, natural bodies of standing fresh water • formed when precipitation, runoff, groundwater seepage fills depressions in earth’s surface – depressions can be formed by » glaciation (Great Lakes, NA) » crustal displacement (Lake Nyasa, East Africa) » volcanic activity (Crater Lake, Oregon) • lar ...
seamount subduction and earthquakes
... studies of trench seamounts exist, but recent surveys over Daiichi-Kashima (Nishizawa et al., 2009) and the ...
... studies of trench seamounts exist, but recent surveys over Daiichi-Kashima (Nishizawa et al., 2009) and the ...
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.