Sarah Brown | West Virginia University (original) (raw)

Papers by Sarah Brown

Research paper thumbnail of Double Dating and Oxygen Isotope Analysis of Silicic Lavas and Ignimbrites from the Sierra Madre Occidental Large Igneous Province (Mexico): Insights Into the Sources and Timescales of Magma Generation in an Arc Flare-Up

Geological Society of America Abstracts with Programs, 2017

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Research paper thumbnail of <sup>40</sup>Ar/<sup>39</sup>Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone

Long-lived intra-oceanic arcs of Izu-Bonin-Marianas (IBM)-type are built on thick, granodioritic ... more Long-lived intra-oceanic arcs of Izu-Bonin-Marianas (IBM)-type are built on thick, granodioritic crust formed in the absence of pre-existing continental crust. International Ocean Discovery Program Expedition 350, Site U1437, explored the IBM rear arc to better understand continental crust formation in arcs. Detailed petrochronological (U–Pb geochronology combined with trace elements, oxygen and hafnium isotopes) characterizations of zircon from Site U1437 were carried out, taking care to exclude potential contaminants by (1) comparison of zircon ages with ship-board palaeomagnetic and biostratigraphic ages and <sup>40</sup>Ar/<sup>39</sup>Ar geochronology, (2) analysing zircon from drill muds for comparison, (3) selectively carrying out <i>in situ</i> analysis in petrographic thin sections, and (4) minimizing potential laboratory contamination through using pristine equipment during mineral separation. The youngest zircon ages in Site U1437 are c...

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Research paper thumbnail of Internal architecture of the proto-Kern Canyon Fault at Engineer’s Point, Lake Isabella Dam site, Kern County, California

The core of the Cretaceous (?) proto-Kern Canyon Fault (KCF) is exposed continuously for 1.25 km ... more The core of the Cretaceous (?) proto-Kern Canyon Fault (KCF) is exposed continuously for 1.25 km along Engineers Point at Lake Isabella, Kern County, California. The proto-KCF is notable for (1) its long and complex history within, and perhaps preceding the Sierra Nevada batholith, and (2) hosting the Quaternary Kern Canyon Fault, an active fault that threatens the integrity of the Lake Isabella auxiliary dam and surrounding communities. We are investigating the internal architecture of the proto-KCF to explore its control on the likely behavior of the modern KCF. The proto-KCF is developed in the Alta Sierra biotite-granodiorite pluton. A traverse across Engineers Point, perpendicular to the proto-KCF trace, reveals gradational increases in fracture density, fracture length, bulk alteration, and decreases in fracture spacing and grain size toward the fault core. Mapping of the fault core reveals two prominent and laterally extensive zones: (1) continuous foliated blastomylonitic gr...

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Research paper thumbnail of The Upper- to Middle-Crustal Section of the Alisitos Oceanic Arc, (Baja, Mexico): an Analog of the Izu-Bonin-Marianas (IBM) Arc

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Research paper thumbnail of Structural Analysis of Silicic Lavas Reveals the Importance of Endogenous Flow During Emplacement

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Research paper thumbnail of Fracture Adjacent Matrix Permeability: Insights from a Direct Experimental Approach

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Research paper thumbnail of The Fold Illusion: Large Arcuate Lava-Surface Features are Formed by Tensile Fracturing

Lunar and Planetary Science Conference, Mar 1, 2021

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Research paper thumbnail of Design and implementation of a shearing apparatus for the experimental study of shear displacement in rocks

The Review of scientific instruments, 2018

Fluid flow in the subsurface is not well understood in the context of "impermeable" geo... more Fluid flow in the subsurface is not well understood in the context of "impermeable" geologic media. This is especially true of formations that have undergone significant stress fluctuations due to injection or withdrawal of fluids that alters the localized pressure regime. When the pressure regime is altered, these formations, which are often already fractured, move via shear to reduce the imbalance in the stress state. While this process is known to happen, the evolution of these fractures and their effects on fluid transport are still relatively unknown. Numerous simulation and several experimental studies have been performed that characterize the relationship between shearing and permeability in fractures; while many of these studies utilize measurements of fluid flow or the starting and ending geometries of the fracture to characterize shear, they do not characterize the intermediate stages during shear. We present an experimental apparatus based on slight modification...

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Research paper thumbnail of Rheological and structural constraints on the accumulation of'thick'pseudotachylite

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Research paper thumbnail of The Stratigraphic Record of Syn- and Post-Volcanic Extension Adjacent to the Sierra Madre Occidental Silicic Large Igneous Province, Northern Mexico

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Research paper thumbnail of Computed Tomography Scanning and Geophysical Measurements of the Rogersville Shale from the Smith #1 Well

.................................................................................................... more ...................................................................................................................................1

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Research paper thumbnail of Gouge formation and dilation impacts to flow during fracture shearing

International Journal of Rock Mechanics and Mining Sciences, 2021

Abstract Flow in fractures is of critical importance to fluid flow in low-permeability shales, pa... more Abstract Flow in fractures is of critical importance to fluid flow in low-permeability shales, particularly when they restrict vertical migration from reservoirs. The Mt. Simon Sandstone is a target for geologic CO 2 sequestration and the overlying Eau Claire Formation is the sealing formation capping this reservoir. The lower Eau Claire, a primary barrier to upward migration of CO2 from the Mt. Simon, is lithologically heterogenous with a mixture of sandstone and shale. We use a series of flow-through experiments on fractured samples from the Eau Claire to document the morphological changes taking place in the fracture and surrounding rock as it is sheared in a stepwise fashion. The samples were imaged using computed tomography after each shearing episode and flow resistance was calculated based on the pressure differential across each core. We found that gouge accumulations in the fracture plane led to specific instances of self-sealing behavior despite the fact that most samples increased in average fracture aperture and transmissivity . Gouge limited the increase or, in some cases, decreased flow through these samples. Fractures adjacent to shale-rich zones and concordant with bedding were more likely to show evidence of self-sealing, while increased sandstone content and fracture orientation perpendicular to bedding planes was more likely to result in fracture dilation and fracture permeability increases. Reactivation and shearing of vertical fractures in lithologically heterogenous caprocks is more likely to pose risks to long term CO 2 storage scenarios.

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Research paper thumbnail of Corrugated architecture of the Okanagan Valley shear zone and the Shuswap metamorphic complex, Canadian Cordillera

Lithosphere, 2016

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Research paper thumbnail of The Fold Illusion: Structural and Thermo-Rheological Constraints on the Deformation of Silicic Lavas During Emplacement

AGU Fall Meeting Abstracts, Dec 1, 2020

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Research paper thumbnail of Bench-Top Experiments Evaluating Simulated Hydraulic Fracturing Fluid Interactions with Marcellus Shale Core

Proceedings of the 6th Unconventional Resources Technology Conference, 2018

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Research paper thumbnail of Petrogenesis of voluminous silicic magmas in the Sierra Madre Occidental large igneous province, Mexican Cordillera: Insights from zircon and Hf-O isotopes

Geosphere, 2022

Combined Hf-O isotopic analyses of zircons from tuffs and lavas within the Sierra Madre Occidenta... more Combined Hf-O isotopic analyses of zircons from tuffs and lavas within the Sierra Madre Occidental (SMO) silicic large igneous province are probes of petrogenetic processes in the lower and upper crust. Existing petrogenetic and tectonomagmatic models diverge, having either emphasized significant crustal reworking of hydrated continental lithosphere in an arc above the retreating Farallon slab or significant input of juvenile mantle melts through a slab window into an actively stretching continental lithosphere. New isotopic data are remarkably uniform within and between erupted units across the spatial and temporal extent of the SMO, consistent with homogeneous melt production and evolution. Isotopic values are consistent with enriched mantle magmas (80%) that assimilated Proterozoic paragneisses (~20%) from the lower crust. 18Ozircon values are consistent with fractionation of mafic magma and not with assimilation of hydrothermally altered upper crust, suggesting that the silicic ...

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Research paper thumbnail of Supplemental Material: Petrogenesis of voluminous silicic magmas in the Sierra Madre Occidental large igneous province, Mexican Cordillera: Insights from zircon and Hf-O isotopes

Sample details, U-Pb geochronology data, EarthChem Database references, Lu-Hf data, oxygen isotop... more Sample details, U-Pb geochronology data, EarthChem Database references, Lu-Hf data, oxygen isotope data, zircon saturation temperature data, and assimilation–fractional crystallization modeling

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Research paper thumbnail of Potential for a Critical Mineral Resource in the Underclays of West Virginia

Geological Society of America Abstracts with Programs, 2020

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Research paper thumbnail of Integration of a Small Unpiloted Airborne System, Photogrammetry, and Fieldmove for Meter-Scale Structural and Facies Mapping of the Surfaces of Obsidian Lavas

Geological Society of America Abstracts with Programs, 2020

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Research paper thumbnail of Geochronology and Geochemistry of Zircons from the IODP Site U1437 in the Rear of the Izu-Bonin Volcanic Arc

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Research paper thumbnail of Double Dating and Oxygen Isotope Analysis of Silicic Lavas and Ignimbrites from the Sierra Madre Occidental Large Igneous Province (Mexico): Insights Into the Sources and Timescales of Magma Generation in an Arc Flare-Up

Geological Society of America Abstracts with Programs, 2017

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Research paper thumbnail of <sup>40</sup>Ar/<sup>39</sup>Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone

Long-lived intra-oceanic arcs of Izu-Bonin-Marianas (IBM)-type are built on thick, granodioritic ... more Long-lived intra-oceanic arcs of Izu-Bonin-Marianas (IBM)-type are built on thick, granodioritic crust formed in the absence of pre-existing continental crust. International Ocean Discovery Program Expedition 350, Site U1437, explored the IBM rear arc to better understand continental crust formation in arcs. Detailed petrochronological (U–Pb geochronology combined with trace elements, oxygen and hafnium isotopes) characterizations of zircon from Site U1437 were carried out, taking care to exclude potential contaminants by (1) comparison of zircon ages with ship-board palaeomagnetic and biostratigraphic ages and <sup>40</sup>Ar/<sup>39</sup>Ar geochronology, (2) analysing zircon from drill muds for comparison, (3) selectively carrying out <i>in situ</i> analysis in petrographic thin sections, and (4) minimizing potential laboratory contamination through using pristine equipment during mineral separation. The youngest zircon ages in Site U1437 are c...

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Research paper thumbnail of Internal architecture of the proto-Kern Canyon Fault at Engineer’s Point, Lake Isabella Dam site, Kern County, California

The core of the Cretaceous (?) proto-Kern Canyon Fault (KCF) is exposed continuously for 1.25 km ... more The core of the Cretaceous (?) proto-Kern Canyon Fault (KCF) is exposed continuously for 1.25 km along Engineers Point at Lake Isabella, Kern County, California. The proto-KCF is notable for (1) its long and complex history within, and perhaps preceding the Sierra Nevada batholith, and (2) hosting the Quaternary Kern Canyon Fault, an active fault that threatens the integrity of the Lake Isabella auxiliary dam and surrounding communities. We are investigating the internal architecture of the proto-KCF to explore its control on the likely behavior of the modern KCF. The proto-KCF is developed in the Alta Sierra biotite-granodiorite pluton. A traverse across Engineers Point, perpendicular to the proto-KCF trace, reveals gradational increases in fracture density, fracture length, bulk alteration, and decreases in fracture spacing and grain size toward the fault core. Mapping of the fault core reveals two prominent and laterally extensive zones: (1) continuous foliated blastomylonitic gr...

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Research paper thumbnail of The Upper- to Middle-Crustal Section of the Alisitos Oceanic Arc, (Baja, Mexico): an Analog of the Izu-Bonin-Marianas (IBM) Arc

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structural Analysis of Silicic Lavas Reveals the Importance of Endogenous Flow During Emplacement

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fracture Adjacent Matrix Permeability: Insights from a Direct Experimental Approach

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Fold Illusion: Large Arcuate Lava-Surface Features are Formed by Tensile Fracturing

Lunar and Planetary Science Conference, Mar 1, 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Design and implementation of a shearing apparatus for the experimental study of shear displacement in rocks

The Review of scientific instruments, 2018

Fluid flow in the subsurface is not well understood in the context of "impermeable" geo... more Fluid flow in the subsurface is not well understood in the context of "impermeable" geologic media. This is especially true of formations that have undergone significant stress fluctuations due to injection or withdrawal of fluids that alters the localized pressure regime. When the pressure regime is altered, these formations, which are often already fractured, move via shear to reduce the imbalance in the stress state. While this process is known to happen, the evolution of these fractures and their effects on fluid transport are still relatively unknown. Numerous simulation and several experimental studies have been performed that characterize the relationship between shearing and permeability in fractures; while many of these studies utilize measurements of fluid flow or the starting and ending geometries of the fracture to characterize shear, they do not characterize the intermediate stages during shear. We present an experimental apparatus based on slight modification...

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Research paper thumbnail of Rheological and structural constraints on the accumulation of'thick'pseudotachylite

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Stratigraphic Record of Syn- and Post-Volcanic Extension Adjacent to the Sierra Madre Occidental Silicic Large Igneous Province, Northern Mexico

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Computed Tomography Scanning and Geophysical Measurements of the Rogersville Shale from the Smith #1 Well

.................................................................................................... more ...................................................................................................................................1

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Research paper thumbnail of Gouge formation and dilation impacts to flow during fracture shearing

International Journal of Rock Mechanics and Mining Sciences, 2021

Abstract Flow in fractures is of critical importance to fluid flow in low-permeability shales, pa... more Abstract Flow in fractures is of critical importance to fluid flow in low-permeability shales, particularly when they restrict vertical migration from reservoirs. The Mt. Simon Sandstone is a target for geologic CO 2 sequestration and the overlying Eau Claire Formation is the sealing formation capping this reservoir. The lower Eau Claire, a primary barrier to upward migration of CO2 from the Mt. Simon, is lithologically heterogenous with a mixture of sandstone and shale. We use a series of flow-through experiments on fractured samples from the Eau Claire to document the morphological changes taking place in the fracture and surrounding rock as it is sheared in a stepwise fashion. The samples were imaged using computed tomography after each shearing episode and flow resistance was calculated based on the pressure differential across each core. We found that gouge accumulations in the fracture plane led to specific instances of self-sealing behavior despite the fact that most samples increased in average fracture aperture and transmissivity . Gouge limited the increase or, in some cases, decreased flow through these samples. Fractures adjacent to shale-rich zones and concordant with bedding were more likely to show evidence of self-sealing, while increased sandstone content and fracture orientation perpendicular to bedding planes was more likely to result in fracture dilation and fracture permeability increases. Reactivation and shearing of vertical fractures in lithologically heterogenous caprocks is more likely to pose risks to long term CO 2 storage scenarios.

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Research paper thumbnail of Corrugated architecture of the Okanagan Valley shear zone and the Shuswap metamorphic complex, Canadian Cordillera

Lithosphere, 2016

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Research paper thumbnail of The Fold Illusion: Structural and Thermo-Rheological Constraints on the Deformation of Silicic Lavas During Emplacement

AGU Fall Meeting Abstracts, Dec 1, 2020

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Research paper thumbnail of Bench-Top Experiments Evaluating Simulated Hydraulic Fracturing Fluid Interactions with Marcellus Shale Core

Proceedings of the 6th Unconventional Resources Technology Conference, 2018

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Research paper thumbnail of Petrogenesis of voluminous silicic magmas in the Sierra Madre Occidental large igneous province, Mexican Cordillera: Insights from zircon and Hf-O isotopes

Geosphere, 2022

Combined Hf-O isotopic analyses of zircons from tuffs and lavas within the Sierra Madre Occidenta... more Combined Hf-O isotopic analyses of zircons from tuffs and lavas within the Sierra Madre Occidental (SMO) silicic large igneous province are probes of petrogenetic processes in the lower and upper crust. Existing petrogenetic and tectonomagmatic models diverge, having either emphasized significant crustal reworking of hydrated continental lithosphere in an arc above the retreating Farallon slab or significant input of juvenile mantle melts through a slab window into an actively stretching continental lithosphere. New isotopic data are remarkably uniform within and between erupted units across the spatial and temporal extent of the SMO, consistent with homogeneous melt production and evolution. Isotopic values are consistent with enriched mantle magmas (80%) that assimilated Proterozoic paragneisses (~20%) from the lower crust. 18Ozircon values are consistent with fractionation of mafic magma and not with assimilation of hydrothermally altered upper crust, suggesting that the silicic ...

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Research paper thumbnail of Supplemental Material: Petrogenesis of voluminous silicic magmas in the Sierra Madre Occidental large igneous province, Mexican Cordillera: Insights from zircon and Hf-O isotopes

Sample details, U-Pb geochronology data, EarthChem Database references, Lu-Hf data, oxygen isotop... more Sample details, U-Pb geochronology data, EarthChem Database references, Lu-Hf data, oxygen isotope data, zircon saturation temperature data, and assimilation–fractional crystallization modeling

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Research paper thumbnail of Potential for a Critical Mineral Resource in the Underclays of West Virginia

Geological Society of America Abstracts with Programs, 2020

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Research paper thumbnail of Integration of a Small Unpiloted Airborne System, Photogrammetry, and Fieldmove for Meter-Scale Structural and Facies Mapping of the Surfaces of Obsidian Lavas

Geological Society of America Abstracts with Programs, 2020

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Research paper thumbnail of Geochronology and Geochemistry of Zircons from the IODP Site U1437 in the Rear of the Izu-Bonin Volcanic Arc

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