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Full-Text Articles in Geology

Migmatite Formation, Geochronometer Petrogeneisis, And Rare Earth Element Mineralization In The Adirondack Mountains, Ny, Kaitlyn Suarez Nov 2023

Migmatite Formation, Geochronometer Petrogeneisis, And Rare Earth Element Mineralization In The Adirondack Mountains, Ny, Kaitlyn Suarez

Doctoral Dissertations

The Adirondack Mountains in upstate New York contain exposures of complex partially melted rocks, in addition to iron oxide-apatite (IOA) deposits with variable rare earth element (REE) concentrations. Previous workers have suggested that melting occurred during the ca. 1150 Ma Shawinigan and the ca. 1050 Ma Ottawan orogenies. However, there are challenges in determining the timing of melting and the number of partial melt events. Further, tectonic models must be developed to describe the petrogenesis of IOA and REE mineralization. Migmatites are present along Rt. 4/22 near Whitehall, NY. In chapter two, all layers of a single migmatitic rock were …


Implications And Significance Of Partial Melting On The Tectonic History Of The Eastern Adirondack Mountains, Claire Rose Pless Dec 2020

Implications And Significance Of Partial Melting On The Tectonic History Of The Eastern Adirondack Mountains, Claire Rose Pless

Doctoral Dissertations

The eastern Adirondack Mountains contain abundant exposures of high-grade metamorphic rocks. These exposures are interpreted to be a window into the mid/deep crust of an ancient, large, hot, long-duration orogen, allowing the Adirondack Mountains to be used as an analogue to the deep processes of modern orogens. Currently interpreted thermo-tectonic events in the eastern Adirondack Mountains include the ca. 1245-1220 Ma Elzevirian orogeny, the ca. 1190-1150 Ma Shawinigan orogeny, emplacement of the ca. 1150 Ma AMCG igneous suite, the ca. 1090-1050 Ma Ottawan orogeny, and a ca. 1050-1020 Ma extensional collapse phase. This dissertation focuses on six migmatite domains within …


3-D Shear Wave Velocity Structures Of The Crust And Upper Mantle Beneath Cascadia And New Zealand From Full-Wave Ambient Noise Tomography, Sampath Rathnayaka Mudiyanselage Jul 2020

3-D Shear Wave Velocity Structures Of The Crust And Upper Mantle Beneath Cascadia And New Zealand From Full-Wave Ambient Noise Tomography, Sampath Rathnayaka Mudiyanselage

Doctoral Dissertations

The (de)hydration process and the amount of hydrated sediment carried by the downgoing oceanic plate play a key role in the subduction dynamics. The deformation and (de)hydration of the downgoing tectonic plates, as well as the seismic, tsunami, volcanic hazards, in Cascadia and the New Zealand regions are not fully understood, partly due to a lack of combined studies of onshore and offshore data. In order to address these questions, we developed a 3-D high-resolution shear wave velocity model beneath Cascadia, the North and the South Islands of New Zealand, extending from offshore to onshore, with the use of full-wave …


A New Paradigm For Predicting Fracture Growth, Interaction And Linkage: Faulting In Numerical And Physical Experiments With Work Optimization, Jessica Mcbeck Jul 2017

A New Paradigm For Predicting Fracture Growth, Interaction And Linkage: Faulting In Numerical And Physical Experiments With Work Optimization, Jessica Mcbeck

Doctoral Dissertations

This dissertation predicts fracture propagation and interaction within the framework of work optimization. With this approach, fractures are predicted to propagate along the path that optimizes work. This dissertation includes three projects that predict fracture growth using work optimization in varying tectonic environments. The projects build on work completed during my M.S. at UMass, which includes the development of the fracture modeling tool Growth by Optimization of Work (GROW) [McBeck et al., 2016]. GROW simulates fracture propagation, interaction and linkage by iteratively searching for fracture propagation paths that maximize the change in external work done on the system …


Metamorphic And Structural Control Of Magnetism Within The Lower Continental Crust, Northern Saskatchewan, Canada, Jeffrey R. Webber Nov 2016

Metamorphic And Structural Control Of Magnetism Within The Lower Continental Crust, Northern Saskatchewan, Canada, Jeffrey R. Webber

Doctoral Dissertations

The linking of geophysical information to tectonometamorphic processes holds great potential for the surveying of vast remote areas of the planet and may allow for the transcendence of observational scales. Investigations concerning magnetic properties of the lower continental crust can reveal an incredible wealth of information concerning the conditions of metamorphism, regional extent of deformation, and controls on the magnetic architecture of the lithosphere. This dissertation presents three contributions aimed at the integration of petrology, structural geology, and rock magnetism in order to investigate the magnetic nature of the lower continental crust, constrain tectonometamorphic processes at the regional scale in …