Global ETD Search
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Showing 1 to 14 of 14 for “"underplating"”.
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Contractional tectonics : the Himalayan orogen and Perdido fold-thrust belt
… to two end-member regimes: extrusion versus underplating. To determine how the crystalline core evolved, an integrated investigation was conducted, involving structural mapping, microstructural, quartz c-axis fabric, and geochronological analyses across the northern margins of two frontal …
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Plume-lithosphere interaction : geochemical evidence from upper mantle and lower crusal Xenoliths from the Kerguelen Islands
… melts emplaced at the base of the crust by underplating and subsequently recrystallized isobarically under granulite conditions. The Sr, Nd and Os isotopic compositions of the peridotite and granulite xenoliths demonstrate that the Kerguelen plume is isotopically heterogeneous and displays a …
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Plume-lithosphere interaction : geochemical evidence from upper mantle and lower crustal xenoliths from the Kerguelen Islands
… melts emplaced at the base of the crust by underplating and subsequently recrystallized isobarically under granulite conditions. The Sr, Nd and Os isotopic compositions of the peridotite and granulite xenoliths demonstrate that the Kerguelen plume is isotopically heterogeneous and displays a …
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Sediment incorporation into continental arc systems and paleogeography of the western North American Cordillera: Insights from the North Cascades, Washington
… transferred to depth by either underthrusting or underplating of sediments that originated outboard of the arc system. The MDAs coupled with in situ peaks indicate vertical burial rates of ~4mm/yr, which are similar to rates observed in modern convergent-margin settings. Although both the Swakane …
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Pre-rift evolution of Malawian high-grade basement rocks
… at 4.3-6 kbar due to Kibaran-age magmatic underplating. Remnants of the Irumide/Kibaran Orogeny is relatively scarce throughout Malawi and although the Mangochi charnockites were emplaced during Kibaran-age tectonism, it also experienced at least two different metamorphic events thereafter. …
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Continental Tectonics from Dense Array Seismic Imaging: Intraplate Seismicity in Virginia and a Steep Cratonic Margin in Idaho
… In the lower crust there is evidence of magmatic underplating which is consistent with the location of the feeder system of the Columbia River Basalts. The cratonic crust east of the WISZ is thicker and characterized by a felsic composition dominated by granite through most of the crust, with an …
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Tectonic-Climate Interactions And Glacial History Within The Chugach And Kenai Mountains, Alaska
… of the Kenai Peninsula to subduction and underplating of sediment shed from the accreting Yakutat microplate to the east. A delineation of the glacial history using 10Be cosmogenic dating depict a series of glacial advances which date to the early and late Wisconsin. We find that the …
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Subduction dynamics at the middle America trench : new constraints from swath bathymetry, multichannel seismic data, and 10BE
… sediment column, leading to subsequent underplating and therefore removal of the bulk of the sediment layer that contains 10Be. Basement fault relief was linearly related to plate curvature and trench depth. The systematic shoaling of the plate from southeastern Nicaragua to northwestern …
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Geology, Petrology, and Tectonic Setting of the Mafic Rocks of the 1480 MA Old Granite-Rhyolite Terrane of Missouri, USA
… crustal melting may have been induced by mafic underplating. Although speculative, the mafic granulites could represent a portion of the mafic underplate. The 1500 to 1400 Ma old belt probably formed in an extensional tectonic setting. The Basin and Range province of the western United States …
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GEOCHEMISTRY OF LARGE EXPLOSIVE ERUPTIONS FROM THE MAIN ETHIOPIAN RIFT
… due to thermal perturbations during basaltic underplating? 2) why are the intermediate compositions minor in the geological record? 3) What are the conditions that allow the development of peralkalinity in the SiO2-rich magmas? This thesis mainly focuses on the study of two large, low …
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Crustal structure of rifted and convergent margins : the U.S. East Coast and Aleutian margins
… emplacement. We find that magmatic intrusion and underplating of pre-existing continental crust occurs primarily in extended crust and that crustal extension is focused in a 75-km-wide region beneath the shelf and slope. The crust thinned by 50 to 80% within this interval and then seafloor …
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High-temperature metamorphism in the western Namaqua-Natal Metamorphic Province (South Africa): implications for low-pressure granulite terranes
… scale most likely was a mixture of mafic mantle underplating combined with radiogenic heating in a slowly buried juvenile crust. Heat transfer to higher levels of the crust was aided by advective heating via the syn-metamorphic emplacement of the post-tectonic Spektakel Suite that locally led to …
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High-temperature metamorphism in the western Namaqua-Natal Metamorphic Province (South Africa): implications for low-pressure granulite terranes
… scale most likely was a mixture of mafic mantle underplating combined with radiogenic heating in a slowly buried juvenile crust. Heat transfer to higher levels of the crust was aided by advective heating via the syn-metamorphic emplacement of the post-tectonic Spektakel Suite that locally led to …
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Metamorfismo ercinico di bassa-pressione: evoluzione tettonico-metamorfica del complesso di mandatoriccio (massiccio della Sila - Calabria)
… amount of heat has been related to crustal underplating of mantle-derived basic magmas or to thermal perturbation linked to intrusion of large volumes of granitoids in the intermediate crust. In particular, in this latter context, magmatic or aqueous fluids are able to transport relevant …