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Full-Text Articles in Physical Sciences and Mathematics
Birth And Evolution Of The Rio Grande Fluvial System In The Last 8 Ma:Progressive Downward Integration And Interplay Between Tectonics, Volcanism, Climate, And River Evolution, Marisa N. Repasch
Earth and Planetary Sciences ETDs
The Rio Grande-Rio Chama (RG-RC) fluvial system has evolved dramatically over the last 8 Ma, undergoing channel migrations, drainage capture and integration events, volcanic damming, and carving and refilling of paleocanyons. Volcanism concurrent with the development of the river system provides a unique opportunity to apply multiple geochronometers to the study of its incision and drainage evolution. This paper reports 19 new 40Ar/39Ar basalt ages and 19 detrital mineral samples (zircon and sanidine) collected from RG-RC alluvium overlain by dated basalt flows in the context of a compilation of published 40Ar/39Ar basalt ages. The …
Structure And Geochronology Of The White Fork Pluton, Southern Sierra Nevada, Ian Richard Mahaffey
Structure And Geochronology Of The White Fork Pluton, Southern Sierra Nevada, Ian Richard Mahaffey
Natural Resources Management and Environmental Sciences
The Sierra Nevada batholith represents an archetypal continental arc, although the style of deformation throughout the history of the arc is only poorly understood, in part due to the voluminous nature of Late Cretaceous magmatism that has overprinted earlier structures. The purpose of this study is to gain a better understanding of pre-Late Cretaceous deformation in the Sierra Nevada batholith through a structural and geochronological study of the Jurassic White Fork pluton. A Jurassic age for the White Fork pluton is indicated by its inclusion of numerous 148 Ma Independence dikes, and geochronology on the White Fork pluton is limited …
Resolving Paragneiss Provenance At Grollier Lake In The Athabasca Granulite Terrane, Western Canadian Shield, Dustin Ply
Resolving Paragneiss Provenance At Grollier Lake In The Athabasca Granulite Terrane, Western Canadian Shield, Dustin Ply
Graduate Theses and Dissertations
U-Pb crystallization ages of metamorphic and detrital zircons from all three paragneiss samples fall into the range of ca. 1.85-2.59 Ga, excluding two much older grains. Evidence suggests that the paragneiss of Grollier Lake record deformation exclusively from the Taltson and Trans-Hudson orogenies. It is apparent from geochronological data that the Taltson orogeny played an exceedingly larger role in the deformation of these rocks than the Trans-Hudson. Deposition of the paragneiss protoliths most likely culminated between ca. 2037-1994 Ma with metamorphism ceasing by 1852.1 ± 11.1 Ma. The oldest overgrowth considered to be concordant is 1994 ± 12 Ma and …
The Relationship Between Magmatism And Deformation During The Acadian Orogeny: A Case Study From Eastern-Central Vermont, Samuel William Lagor
The Relationship Between Magmatism And Deformation During The Acadian Orogeny: A Case Study From Eastern-Central Vermont, Samuel William Lagor
Graduate College Dissertations and Theses
The Silurian-Devonian metasedimentary rocks of the Connecticut Valley-Gaspé trough (CVGT) were subjected to multiple deformational and metamorphic events during the Acadian orogeny in the Middle-Late Devonian. Plutons intruding the Devonian Waits River and Gile Mountain Formations have been considered post-tectonic, but microstructural studies of the intrusions and their metamorphic aureoles indicate some of these plutons intruded syntectonically. This study investigates the relationship between Acadian deformation and intrusion of the Knox Mountain pluton (KMP) of central Vermont. Structural and geochronological data were collected along a c. 15 km transect from the western limit of the CVGT, where the unconformable Richardson Memorial …