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Showing 1 to 20 of 47 for “"Grenville"”.
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Crustal evolution of Grenville terranes in the central and southern Appalachians: the Pb isotope perspective for Grenville tectonics
Nine basement blocks were sampled from locations spanning from Pennsylvania to Georgia in the eastern United States. These basement blocks are similar in that they have radiometric ages of approximately 1.0 billion years (with one exception), they are all at upper amphibolite to granulite grades, …
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The thermal structure of collisional orogens – insights from the Grenville orogen in Canada and Scotland
… the study of the Mesoproterozoic (c. 1.1–1.0 Ga) Grenville orogen, integrating P–T results from phase equilibrium modelling, age constraints from U-Pb zircon and monazite geochronology, structural observations and measurements, and regional geological and geophysical datasets. My research focuses …
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The New York-Alabama Magnetic Lineament: its reflection character and relationship to the Grenville front
… reprocessed seismic reflection data, and the Grenville Front Tectonic Zone (GFTZ) is imaged beneath it in eastern Tennessee. Industry data, correlated to lower crustal depths, image a wedge-shaped block beneath the shelf strata of the Cumberland Plateau and Valley and Ridge provinces of …
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Pre-Grenville ages of basement rocks in central Virginia: a model for the interpretation of zircon ages
Late to Middle Precambrian basement rocks in the Blue Ridge of Central Virginia represent a heterogeneous admixture of highly deformed gneisses, paragneisses and igneous intrusives, which have undergone multiple periods of metamorphism. Isotopic U-Pb age determinations on the Lovingston Formation …
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The petrology and geochemistry of the minor intrusions in the central metasedimentary belt, Grenville Province, southern Ontario, Canada.
The study area lies within the western section of the Elzevir terrane, in the Central Metasedimentary Belt. A supracrustal sequence of carbonates and clastic metasediments, interdigitating with metavolcanics occur in this area, intruded by a series of dykes. The majority of minor intrusions are …
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The origin and tectonic significance of the mafic-ultramafic association in the central Virginia Blue Ridge post-Grenville cover sequence
The question of whether the mafic and ultramafic rocks of the central Virginia Blue Ridge are part of a Late Proterozoic to Ordovician ophiolite-bearing sequence or part of an intrusive-extrusive sequence related to the Late Proterozoic Iapetan rifting has major implications for Appalachian …
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DETRITAL-ZIRCON GEOCHRONOLOGIC PROVENANCE ANALYSES THAT TEST AND EXPAND THE EAST SIBERIA - WEST LAURENTIA RODINIA RECONSTRUCTION
… of the crust during the southern Laurentian Grenville orogeny, crustal flexure resulting in a foreland basin, and extension sub-perpendicular to the Grenville front resulting in extensional basins within the foreland basin on both cratons. Sediments were transported from the Grenville Orogen …
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DETRITAL-ZIRCON GEOCHRONOLOGIC PROVENANCE ANALYSES THAT TEST AND EXPAND THE EAST SIBERIA - WEST LAURENTIA RODINIA RECONSTRUCTION
… of the crust during the southern Laurentian Grenville orogeny, crustal flexure resulting in a foreland basin, and extension sub-perpendicular to the Grenville front resulting in extensional basins within the foreland basin on both cratons. Sediments were transported from the Grenville Orogen …
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Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-temperature Magmatic Conditions And Non-laurentian Origin Of Earth’s Most Zircon Fertile Magmas
<p>The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to …
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Mesoproterozoic Basement From the Central and Southern Appalachians Reveal High-temperature Magmatic Conditions and Non-laurentian origin of Earth's Most Zircon Fertile Magmas
<p>The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to …
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Recent two-feldspar, Ti-in-biotite, and garnet-biotite geothermometry of the Frontenac terrane and Adirondack Lowlands, Grenville Province, Canada and the United States
<p>Reconstructing the assembly of the Middle Proterozoic Adirondack Mountains and surrounding regions is difficult due to high-grade metamorphism, igneous intrusions, faulting, erosion, and dense cover. A 2008/2009 Keck Geology Consortium Project devoted itself to collecting petrological and …
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Mesoproterozoic tectonic evolution of southwestern North America : protracted intracratonic deformation, sedimentation, and differential exhumation in Grand Canyon and the Rocky Mountain Region
… kinematically compatible with protracted "Grenville-age" NW-directed shortening. New U/Pb age determinations from tephra at the base of the Unkar Group date the onset of deposition at ca. 1254 Ma. 40Ar/39Ar Kfeldspar thermochronology in Grand Canyon indicates that basement rocks cooled …
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Geologic framework of gravity anomaly sources in the central Piedmont of Virginia
… gm/cc, Maidens Gneiss-2.775 gm/cc, Grenville Basement- 2.71 gm/cc. Gravity and seismic data are consistent with the existence of a major thrust fault at depths between 9 km and 16 km that separates Grenville Basement rocks from younger Catoctin/Lynchburg rocks. The slight eastward …
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Geology and Tectonic Significance of the Late Precambrian Eastern Blue Ridge Cover Sequence in Central Virginia
… biotite gneisses that unconformably overlie the Grenville basement. The Lynchburg Group in central Virginia is divided into three formations. Lynchburg I is made up of massive to thick bedded coarse-grained feldspathic arenites and conglomerates, which are interpreted as slope-apron deposits. …
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The Global Detrital Zircon Database: Quantifying the Timing and Rate of Crustal Growth
… with a peak at 400-450 Ma and a paucity of Grenville-age zircons. Comparison of the Dry Fork sample to published east coast data and to the North American record (from the GDZDb) illustrate the unusual nature of the Dry Fork Formation sample. It is probable that older Grenville zircons were …
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A geologic and potential field investigation of the central Virginia Piedmont
… structure is the easternmost known outcrop of Grenville basement, the State Farm Gneiss. The eastern limb of the antiform coincides with a zone of late Paleozoic mylonitization, the Hylas Zone, and the western border fault of the Richmond Triassic Basin. The crest of a major gravity anomaly, …
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Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems
… belts; in Fennoscandia, in North American Grenville and in the Birimian terrane of the West African craton. The eastern part of the Sveconorwegian Province, located in the southwestern part of the Fennoscandian Shield, is made up of granitiod rocks that were emplaced through sequential …
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