Trace element patterns show that Guatemala rocks
... wedge margin. Lithium abundances and isotopes have been measured on these rocks using MC-ICP-MS, to better understand the evolution of fluids and fluid exchange during subduction. Several lines of evidence suggest that the rocks were metasomatized in the subduction zone environment. Although the ec ...
... wedge margin. Lithium abundances and isotopes have been measured on these rocks using MC-ICP-MS, to better understand the evolution of fluids and fluid exchange during subduction. Several lines of evidence suggest that the rocks were metasomatized in the subduction zone environment. Although the ec ...
macpherson_hall_1999 Tectonic controls on arc magmatism
... Halmahera and Bacan. High values for Zr/Nb ratios occur in melts derived from mantle that has experienced previous melt extraction (Woodhead et al, 1993) and probably require a relatively high fluid flux to induce melting. Thus, the Neogene data for Halmahera are consistent with a mantle wedge that ...
... Halmahera and Bacan. High values for Zr/Nb ratios occur in melts derived from mantle that has experienced previous melt extraction (Woodhead et al, 1993) and probably require a relatively high fluid flux to induce melting. Thus, the Neogene data for Halmahera are consistent with a mantle wedge that ...
05c_U7E_PlanetEarth_p396-410
... Magma rises from deep within Earth and flows out at the ridge. On either side of the ridge, scientists found that the farther rock is away from the top of the ridge, the older the rock is. This means that the rock must be moving away from the ridge and toward the continents. Evidence showed that thi ...
... Magma rises from deep within Earth and flows out at the ridge. On either side of the ridge, scientists found that the farther rock is away from the top of the ridge, the older the rock is. This means that the rock must be moving away from the ridge and toward the continents. Evidence showed that thi ...
The Puzzling Plates – Part I
... a. Examine the classroom globe to see approximately how large the Antarctic Plate is relative to the Pacific Plate. This plate is mostly continental (not all of the continent is shown on the puzzle) and it is surrounded by a ridge that connects the three oceans. ...
... a. Examine the classroom globe to see approximately how large the Antarctic Plate is relative to the Pacific Plate. This plate is mostly continental (not all of the continent is shown on the puzzle) and it is surrounded by a ridge that connects the three oceans. ...
Archean Geodynamics and the Thermal Evolution of Earth
... framework of simple whole-mantle convection. The geological record of supercontinents back to ~2.7 Ga is shown to be broadly consistent with the accelerating plate motion as predicted by the new model. Furthermore, the very fact of repeated continental aggregation indicates that thicker depleted lit ...
... framework of simple whole-mantle convection. The geological record of supercontinents back to ~2.7 Ga is shown to be broadly consistent with the accelerating plate motion as predicted by the new model. Furthermore, the very fact of repeated continental aggregation indicates that thicker depleted lit ...
ONE THE PLATE TECTONICS REVOLUTION
... No schoolchild who looks at a globe can help but be struck by an observation as simple as it is obvious: South America and Africa would µt together if they could be slid magically toward each other. Surely this is not a coincidence; surely these two continents were at one time joined. Upon learning ...
... No schoolchild who looks at a globe can help but be struck by an observation as simple as it is obvious: South America and Africa would µt together if they could be slid magically toward each other. Surely this is not a coincidence; surely these two continents were at one time joined. Upon learning ...
Synthesis of Results From the CD-ROM Experiment
... velocity, mantle anomaly is that it is an ancient slab fragment, for example a remnant of the rifted margin of the Wyoming Province (Tyson et al., 2002) or a collapsed back-arc basin (Yuan and Dueker, this volume; Zurek and Dueker, this volume). Our interpretation is that Proterozoic oceanic lithosp ...
... velocity, mantle anomaly is that it is an ancient slab fragment, for example a remnant of the rifted margin of the Wyoming Province (Tyson et al., 2002) or a collapsed back-arc basin (Yuan and Dueker, this volume; Zurek and Dueker, this volume). Our interpretation is that Proterozoic oceanic lithosp ...
The Moho in subduction zones - Earth and Space Sciences at the
... crustal Layer 2, is consistent with available geological and geophysical data, and reconciles previously conflicting interpretations. In this model, the upper oceanic crust is hydrated through intense circulation at the ridge and becomes overpressured upon subduction as a result of metamorphic dehydr ...
... crustal Layer 2, is consistent with available geological and geophysical data, and reconciles previously conflicting interpretations. In this model, the upper oceanic crust is hydrated through intense circulation at the ridge and becomes overpressured upon subduction as a result of metamorphic dehydr ...
Re^Os evidence for replacement of ancient mantle
... The Western Block is characterized by late Archean to Paleoproterozoic metasedimentary belts that unconformably overlie Archean basement [17,21,22], which consists of granulite facies TTG gneiss and charnockite (3300 Ma) [23] with minor ma¢c granulite and amphibolites. Separating the two blocks is t ...
... The Western Block is characterized by late Archean to Paleoproterozoic metasedimentary belts that unconformably overlie Archean basement [17,21,22], which consists of granulite facies TTG gneiss and charnockite (3300 Ma) [23] with minor ma¢c granulite and amphibolites. Separating the two blocks is t ...
SoE2 Geological changes earth`s structure
... The present distribution of the continents and oceans on the surface of our planet is the result of the movement of slabs of lithosphere otherWIse known as plates. This movement has been going on for hundreds of millions of years and is responsible for many of the features and rocks that form the E ...
... The present distribution of the continents and oceans on the surface of our planet is the result of the movement of slabs of lithosphere otherWIse known as plates. This movement has been going on for hundreds of millions of years and is responsible for many of the features and rocks that form the E ...
Mobility and immobility of mid-ocean ridges and their implications to
... The observations that the SWIR may be tapping the same portion of the mantle as did the CIR, and the correlation between absolute migration velocity and the depth of origin of mid-ocean ridges has far-reaching thermal and chemical implications. One of the most important dynamic processes in the eart ...
... The observations that the SWIR may be tapping the same portion of the mantle as did the CIR, and the correlation between absolute migration velocity and the depth of origin of mid-ocean ridges has far-reaching thermal and chemical implications. One of the most important dynamic processes in the eart ...
PDF
... by elevated abundances of immobile incompatible trace elements (Fig. 4A), the most incompatible of which are one to two orders of magnitude enriched relative to normal midoceanic ridge basalt (N-MORB). This implies that the alkalic mafic magma was derived from extremely low degree of partial melts ( ...
... by elevated abundances of immobile incompatible trace elements (Fig. 4A), the most incompatible of which are one to two orders of magnitude enriched relative to normal midoceanic ridge basalt (N-MORB). This implies that the alkalic mafic magma was derived from extremely low degree of partial melts ( ...
When Plates Collide:
... Geophysical adventure – data is king: instrumentation around the globe – expanding to more challenging environments ! Are smartphones next? ...
... Geophysical adventure – data is king: instrumentation around the globe – expanding to more challenging environments ! Are smartphones next? ...
Organization of the tectonic plates in the last 200Myr
... with the physical location of plate boundaries is greater and reaches one hundred of kilometres (e.g. by multiplying the time uncertainties by the fastest plate velocities: 1 Myr 10 cm/ yr¼ 100 km). Completely vanished basins cannot be directly identified, but plate boundary inception and cessation ...
... with the physical location of plate boundaries is greater and reaches one hundred of kilometres (e.g. by multiplying the time uncertainties by the fastest plate velocities: 1 Myr 10 cm/ yr¼ 100 km). Completely vanished basins cannot be directly identified, but plate boundary inception and cessation ...
The reflection seismic survey of project TIPTEQ—the inventory of the
... & Shreve (1988) is a zone with varying thickness above the oceanic crust in which material being transported downwards, exhibits a velocity gradient with respect to both plates. The material flowing within the subduction channel is derived from trench deposits, off scrapings from the base of the upp ...
... & Shreve (1988) is a zone with varying thickness above the oceanic crust in which material being transported downwards, exhibits a velocity gradient with respect to both plates. The material flowing within the subduction channel is derived from trench deposits, off scrapings from the base of the upp ...
The Hadean-Archaean Environment
... only in the uppermost relatively cool region (500 m) of the oceanic crust. The limited mass of CaO and MgO (each 10% by weight) could take up worldwide only 10 bars of CO2 at any one time in carbonates. Repeated carbonatization of the oceanic crust and it subsequent subduction of some kind was ne ...
... only in the uppermost relatively cool region (500 m) of the oceanic crust. The limited mass of CaO and MgO (each 10% by weight) could take up worldwide only 10 bars of CO2 at any one time in carbonates. Repeated carbonatization of the oceanic crust and it subsequent subduction of some kind was ne ...
letters - Noble Gas Geochemistry Lab
... upwelling of a thermal anomaly from the core–mantle boundary; contamination of sub-Indian mantle by the Kerguelen plume; mantle modification by subduction surrounding Gondwana; ancient subduction of altered oceanic crust and sediment; recycled lowercontinental or arc crust; and detachment of SCLM du ...
... upwelling of a thermal anomaly from the core–mantle boundary; contamination of sub-Indian mantle by the Kerguelen plume; mantle modification by subduction surrounding Gondwana; ancient subduction of altered oceanic crust and sediment; recycled lowercontinental or arc crust; and detachment of SCLM du ...
Module Development Template
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... 2011 University of South Florida Libraries. Allwith rightsthe reserved. ...
SEISMIC-WAVE TRANSMISSION ACROSS THE CARIBBEAN
... All shallow (h < 70 km) earthquakes of body-wave magnitudes r a n g i n g between 4.8 a n d 5.7, which occurred along the Antilles island arc during the years 1967, 1968, and part of 1969 a n d were recorded by the short-period instruments of stations C A R , T R N , and by SJG, were considered in t ...
... All shallow (h < 70 km) earthquakes of body-wave magnitudes r a n g i n g between 4.8 a n d 5.7, which occurred along the Antilles island arc during the years 1967, 1968, and part of 1969 a n d were recorded by the short-period instruments of stations C A R , T R N , and by SJG, were considered in t ...
Compositional and Physical Layers of the Earth
... and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions. ...
... and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions. ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.