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Full-Text Articles in Physical Sciences and Mathematics
Evolution Of Off-Fault Deformation Along Analog Strike-Slip Faults, Alexandra E. Hatem
Evolution Of Off-Fault Deformation Along Analog Strike-Slip Faults, Alexandra E. Hatem
Masters Theses
Strike-slip faults evolve to accommodate more fault slip, resulting in less off-fault deformation. In analog experiments, the measured fault slip to off-fault deformation ratios are similar to those measured in crustal strike-slip systems, such as the San Andreas fault system. Established planar faults have the largest fault slip to off-fault deformation ratio of ~0.98. In systems without a pre-existing fault surface, crustal thickness and basal detachment conditions affect shear zone width and roughness. However, once the applied plate displacement is 1-2 times the crustal thickness, partitioning of deformation between fault slip and off-fault distributed shear is >0.90, regardless of the …
The Capacity Of Hydrous Fluids To Transport And Fractionate Incompatible Elements And Metals Within The Earth's Mantle, John Adam, Marek Locmelis, Juan Carlos Afonso, Tracy Rushmer, Marco L. Fiorentini
The Capacity Of Hydrous Fluids To Transport And Fractionate Incompatible Elements And Metals Within The Earth's Mantle, John Adam, Marek Locmelis, Juan Carlos Afonso, Tracy Rushmer, Marco L. Fiorentini
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Both silicate melts and aqueous fluids are thought to play critical roles in the chemical differentiation of the Earth's crust and mantle. Yet their relative effects are poorly constrained. We have addressed this issue by measuring partition coefficients for 50 trace and minor elements in experimentally produced aqueous fluids, coexisting basanite melts, and peridotite minerals. The experiments were conducted at 1.0-4.0 GPa and 950-1200°C in single capsules containing (either 40 or 50 wt %) H2O and trace element-enriched basanite glass. This allowed run products to be easily identified and analyzed by a combination of electron microprobe and LAM-ICP-MS. …
Low-Temperature Deformation Of Mixed Siliciclastic & Carbonate Fault Rocks Of The Copper Creek, Hunter Valley, And Mcconnell Thrusts, Jack R. Hoehn
Low-Temperature Deformation Of Mixed Siliciclastic & Carbonate Fault Rocks Of The Copper Creek, Hunter Valley, And Mcconnell Thrusts, Jack R. Hoehn
Honors Papers
This study analyzes the low-temperature deformation of fault rocks associated thrust faults. Each fault has dominantly carbonate rocks in one wall and dominantly siliciclastic rocks in the other. The rocks from the Hunter Valley and Copper Creek thrusts of the Southern Appalachians, and McConnell thrust of the Canadian Rockies, were analyzed using data extracted at the thin section and SEM scale. The rocks, all of which featured a fine-grained carbonate matrix surrounding larger carbonate and siliciclastic carbonates, all experienced general shearing, but deformed by different deformation mechanisms. The Hunter Valley and McConnell samples showed evidence of cataclasis, diffusive mass transfer, …
Central Cascadia Subduction Zone Creep, Gina M. Schmalzle, Robert Mccaffrey, Kenneth C. Creager
Central Cascadia Subduction Zone Creep, Gina M. Schmalzle, Robert Mccaffrey, Kenneth C. Creager
Geology Faculty Publications and Presentations
Central Cascadia between 43ºN and 46ºN has reduced interseismic uplift observed in geodetic data and coseismic subsidence seen in multiple thrust earthquakes, suggesting elevated persistent fault creep in this section of the subduction zone. We estimate subduction thrust "decade-scale" locking and crustal block rotations from three-component continuous Global Positioning System (GPS) time series from 1997 to 2013, as well as 80 year tide gauge and leveling-derived uplift rates. Geodetic observations indicatecoastal central Oregon is rising at a slower rate than coastal Washington, southern Oregon and northern California. Modeled locking distributions suggest a wide locking transition zone that extends inland undercentral …