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Full-Text Articles in Geology

Continental Saline Environments Interpreted From Bedded Gypsum Of The Triassic Red Peak Formation (Chugwater Group), Northcentral Wyoming, Maya Yamei Bradford Jan 2023

Continental Saline Environments Interpreted From Bedded Gypsum Of The Triassic Red Peak Formation (Chugwater Group), Northcentral Wyoming, Maya Yamei Bradford

Graduate Theses, Dissertations, and Problem Reports

Bedded evaporites and associated red bed siliciclastics record saline lake and groundwater systems from Permo-Triassic Pangea. A major component of these red bed and evaporite systems is bedded gypsum. However, little attention has been paid to the textures of ancient gypsum. Observations of gypsum textures can refine interpretations of depositional environment and diagenetic history. This project describes textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming.

This thesis uses fieldwork, petrography, and x-ray diffraction to describe an outcrop of the upper Red Peak Formation, with a focus on textures of bedded …


Natural Fracture Evolution: Investigations Into The Middle Devonian Marcellus Shale, Appalachian Basin, Usa, Natalie Abigail Mitchell Jan 2023

Natural Fracture Evolution: Investigations Into The Middle Devonian Marcellus Shale, Appalachian Basin, Usa, Natalie Abigail Mitchell

Graduate Theses, Dissertations, and Problem Reports

Optimizing recovery from unconventional shale reservoirs has generated considerable research into optimal recovery methods through hydraulic fracturing design and shale reservoir characterization in the development of long-term hydrocarbon producers. Permeability at multiple scales from nanometer-scale pore sizes and nano-darcy permeability to completion-induced fractures defining a 100’s of meter stimulated reservoir volume plays a significant role in hydrocarbon flow during production in shale reservoirs. Preexisting cemented fractures in unconventional shale reservoirs are abundant and preferentially reactivate during induced hydraulic fracturing treatment to create necessary large-scale permeability. While previous investigations have significantly improved our knowledge of shale reservoirs, it has also highlighted …


Bedrock Channel Geometry: Meter To Micron Scale Controls On Fluvial Incision, Nicholas J. Colaianne Jan 2023

Bedrock Channel Geometry: Meter To Micron Scale Controls On Fluvial Incision, Nicholas J. Colaianne

Graduate Theses, Dissertations, and Problem Reports

The relative resistance of various rock types to incisional processes vary widely and the properties governing bedrock erodibility are poorly understood. Lithologic properties influencing erodibility are the culmination of a rock’s depositional, diagenetic, and exhumation processes. Difficulty identifying a convenient physical proxy for erodibility suggests examining evidence of these processes holistically may offer insight into the role of each in setting a rock’s resistance to incisional forces. In this study we use measured channel geometries along a short stretch of the Dry Fork, WV hosting three distinct lithologic settings to infer relative erodibility against measured and observed fluvial, lithologic, and …


A Study Of Accidental Daughter Crystals In Fluid Inclusions In Bedded Halite From The Permian Opeche Shale And Cedar Hills Sandstone Of The Midcontinental United States, Ryan James Prchlik Jan 2023

A Study Of Accidental Daughter Crystals In Fluid Inclusions In Bedded Halite From The Permian Opeche Shale And Cedar Hills Sandstone Of The Midcontinental United States, Ryan James Prchlik

Graduate Theses, Dissertations, and Problem Reports

Ancient acid-saline lakes of the midcontinental United States deposited bedded halite during Permian time. These deposits are not typically preserved at the surface, but drill cores of the Opeche Shale of North Dakota and Cedar Hills Sandstone of Kansas contain preserved beds of halite. Halite from these ancient lakes have primary fluid inclusions that contain Permian lake water. Also included are accidental daughter crystals that were trapped inside the fluid inclusions at time of halite precipitation. Both the fluid and daughter crystals inside bedded halite can tell us about the geochemistry of original lake waters of Pangea.

Petrography and laser …


Use Of Carbonation For Treatment Of Coal Mine Drainage To Increase Limestone Dissolution And Generate Alkalinity, Dietrich Henry Kuhlmann Iv Jan 2023

Use Of Carbonation For Treatment Of Coal Mine Drainage To Increase Limestone Dissolution And Generate Alkalinity, Dietrich Henry Kuhlmann Iv

Graduate Theses, Dissertations, and Problem Reports

Abstract

Use of Carbonation for Treatment of Coal Mine Drainage to Increase Limestone Dissolution and Generate Alkalinity

Dietrich Kuhlmann IV

Anoxic limestone drains (ALDs) are a common component used within passive treatment systems for coal mine drainage (CMD). Contact between limestone aggregate and CMD results in limestone dissolution, producing carbonate alkalinity. Though ALDs are one of the least expensive CMD treatment technologies, alkalinity generation is limited by limestone solubility. This necessitates a long retention time (>12 hours) and sometimes results in net acidic effluent which requires additional alkalinity generation steps downstream. One way to increase calcite dissolution and alkalinity …


Inverting Passive Margin Stratigraphy For Marine Sediment Transport Dynamics Over Geologic Time, Charles Shobe, Jean Braun, Xiaoping Yuan, Benjamin Campforts, Boris Gailleton, Guillaume Baby, François Guillocheau, Cécile Robin Nov 2022

Inverting Passive Margin Stratigraphy For Marine Sediment Transport Dynamics Over Geologic Time, Charles Shobe, Jean Braun, Xiaoping Yuan, Benjamin Campforts, Boris Gailleton, Guillaume Baby, François Guillocheau, Cécile Robin

Faculty & Staff Scholarship

Passive margin stratigraphy contains time-integrated records of landscapes that have long since vanished. Quantitatively reading the stratigraphic record using coupled landscape evolution and stratigraphic forward models (SFMs) is a promising approach to extracting information about landscape history. However, there is no consensus about the optimal form of simple SFMs because there has been a lack of direct tests against observed stratigraphy in well-constrained test cases. Specifically, the extent to which SFM behaviour over geologic space and timescales should be governed by local (downslope sediment flux depends only on local slope) versus nonlocal (sediment flux depends on factors other than local …


The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker Aug 2022

The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker

Faculty & Staff Scholarship

Bedrock landslides shape topography and mobilize large volumes of sediment. Yet, interactions between landslide-produced sediment and fluvial systems that together govern large-scale landscape evolution are not well understood. To explain morphological patterns observed in steep, landslide-prone terrain, we explicitly model stochastic landsliding and associated sediment dynamics. The model accounts for several common landscape features such as slope frequency distributions, which include values in excess of regional stability limits, quasi-planar hillslopes decorated with straight, closely spaced channel-like features, and accumulation of sediment in valley networks rather than on hillslopes. Stochastic landsliding strongly affects the magnitude and timing of sediment supply to …


Thickness Of Fluvial Deposits Records Climate Oscillations, Xiaoping Yuan, Laure Guerit, Jean Braun, Delphine Rouby, Charles Shobe Apr 2022

Thickness Of Fluvial Deposits Records Climate Oscillations, Xiaoping Yuan, Laure Guerit, Jean Braun, Delphine Rouby, Charles Shobe

Faculty & Staff Scholarship

Fluvial deposits offer Earth’s best-preserved geomorphic record of past climate change over geological timescales. However, quantitatively extracting this information remains challenging in part due to the complexity of erosion, sediment transport and deposition processes and how each of them responds to climate. Furthermore, sedimentary basins have the potential to temporarily store sediments, and rivers subsequently rework those sediments. This may introduce time lags into sedimentary signals and obscure any direct correlation with climate forcing. Here, using a numerical model that combines all three processes—and a new analytical solution—we show that the thickness of fluvial deposits at the outlet of a …


Regional Correlation And Depositional History Using Well Log And Core Data Of The Geneseo-Burket From The Poseidon 8m Well, Westmoreland County Pa, Usa, Spencer Leonard Williams Jr. Jan 2022

Regional Correlation And Depositional History Using Well Log And Core Data Of The Geneseo-Burket From The Poseidon 8m Well, Westmoreland County Pa, Usa, Spencer Leonard Williams Jr.

Graduate Theses, Dissertations, and Problem Reports

Abstract

Regional Correlation and Depositional History using Well Log and Core Data of the Geneseo-Burket from the Poseidon 8M Well, Westmoreland County PA, USA



Spencer Williams

Natural gas producers have invested billions of dollars in Pennsylvania and West Virginia to establish significant gas production from the Devonian Marcellus Shale and the deeper Ordovician Utica-Point Pleasant interval. In addition, commercial gas production has been reported from several other Devonian shale units in the Appalachian region, including the Rhinestreet, Levanna, and Geneseo-Burket. The Marcellus Shale is the largest natural gas play in the United States. The Marcellus is located directly under the …


Understanding Surface Water--Groundwater Connectivity And Discharge In Arctic Deltas, Lindsey N. Aman Jan 2022

Understanding Surface Water--Groundwater Connectivity And Discharge In Arctic Deltas, Lindsey N. Aman

Graduate Theses, Dissertations, and Problem Reports

Increased warming is driving unprecedented hydrologic changes within arctic deltas with implications for water storage, solute processing, and terrestrial and marine ecology. Thermokarst lakes within Arctic deltas store flood waters and filter solutes and sediments, thus moderating the impact of flood water discharge to arctic seas. However, this moderating influence is diminishing as lakes shrink on annual and seasonal time scales, especially close to active channels where lakes are shrinking most rapidly. This study investigates surface water-groundwater connectivity in arctic delta plains with coupled flow and heat transport models to provide a mechanistic understanding of how lake-channel proximity will impact …


Application Of Artificial Intelligence For Co2 Storage In Saline Aquifer (Smart Proxy For Snap-Shot In Time), Marwan Mohammed Alnuaimi Jan 2022

Application Of Artificial Intelligence For Co2 Storage In Saline Aquifer (Smart Proxy For Snap-Shot In Time), Marwan Mohammed Alnuaimi

Graduate Theses, Dissertations, and Problem Reports

In recent years, artificial intelligence (AI) and machine learning (ML) technology have grown in popularity. Smart Proxy Models (SPM) are AI/ML based data-driven models which have proven to be quite crucial in petroleum engineering domain with abundant data, or operations in which large surface/ subsurface volume of data is generated. Climate change mitigation is one application of such technology to simulate and monitor CO2 injection into underground formations.

The goal of the SPM developed in this study is to replicate the results (in terms of pressure and saturation outputs) of the numerical reservoir simulation model (CMG) for CO2 injection into …


The Potential Of Diabase Sills In Eastern Pennsylvania To Store Co2 And H2, Rhiannon R. Schmitt Jan 2022

The Potential Of Diabase Sills In Eastern Pennsylvania To Store Co2 And H2, Rhiannon R. Schmitt

Graduate Theses, Dissertations, and Problem Reports

With anthropogenic CO2 concentrations rising, geologic carbon sequestration and H2 storage are essential processes in mitigating climate change. Typical geologic carbon sequestration involves the capture of anthropogenic CO2 and injection into depleted oil/gas reservoirs or saline formations with an impermeable cap rock to prevent the buoyant migration of CO2. The risk of eventual CO2 migration through these low permeability cap rocks adds expensive monitoring costs to this traditional sequestration strategy. Another method for CO2 sequestration utilizes the reaction of CO2 with mafic and ultramafic rocks. CarbFix, a sequestration project in Iceland, has …


Chemical Characterization Of Clastic Cave Sediments And Insights Into Particle Transport And Storage In Karst Aquifers, Jill L. Riddell Jan 2022

Chemical Characterization Of Clastic Cave Sediments And Insights Into Particle Transport And Storage In Karst Aquifers, Jill L. Riddell

Graduate Theses, Dissertations, and Problem Reports

Abstract

Chemical characterization of clastic cave sediments and insights into particle transport and storage in karst aquifers

Jill L. Riddell

Cave sediments can be divided into two groups: precipitates and clastics. Precipitates are speleothems, or lithologic or mineral features that are chemically precipitated in the cave environment. Clastic cave sediments are frequently described by depositional facies, sorting, and particle size (Bosch and White, 2004). Robust analytical chemical analyses of these sediments to quantify their physical and chemical components is rarely performed although some chemical characterization of mineralogy and paleomagnetism has become prevalent in recent years (Chess et al., 2010; Sasowsky …


Relating Recharge Mechanisms To Dissolved Inorganic Carbon Dynamics In An Updip Appalachian Coal Mine Discharge, Matthew L. Bell May 2021

Relating Recharge Mechanisms To Dissolved Inorganic Carbon Dynamics In An Updip Appalachian Coal Mine Discharge, Matthew L. Bell

Presentations

Impaired drainage from active and abandoned mines degrades the water quality of receiving streams and aquifers. Coal mine drainage (CMD) has been studied for decades in Appalachia, but unknowns and uncertainties are still present, including the influence of mine hydrogeology on the outflow chemistry of above-drainage mines. To evaluate the influence of recharge type on above-drainage mine dissolved inorganic carbon chemistry, samples were collected every two weeks at a CMD outflow treatment system in Harrison County, West Virginia. Samples were collected to measure geochemical changes taking place in the mine workings and along the flowpath of the passive treatment system. …


Comparison Of Methods For Estimating Carbon Evasion And Export Associated With A Coal Mine Discharge, Kyle Lee, Dorothy J. Vesper May 2021

Comparison Of Methods For Estimating Carbon Evasion And Export Associated With A Coal Mine Discharge, Kyle Lee, Dorothy J. Vesper

Presentations

The evasion of CO2 from terrestrial waters plays a role in the global cycling of carbon but there are few datasets that have an accurate accounting of the flux. It has been shown that discharges from coal mines can have elevated concentrations of CO2 due to sulfuric acid-driven dissolution of carbonate rock. In this study, we compared three methods for calculating the export dissolved inorganic carbon (DIC) and the evaluation of CO2 from an abandoned-mine discharge in West Virginia. In Method #1, the source flux is calculated from the discharge and the concentrations at the portal. In Method #2, the …


Quantifying The Contribution Of Solid Precipitates To The Total Alkalinity In A Coal-Mine Discharge, Lili Lei, Dorothy Vesper May 2021

Quantifying The Contribution Of Solid Precipitates To The Total Alkalinity In A Coal-Mine Discharge, Lili Lei, Dorothy Vesper

Presentations

Flocculates and precipitates from coal mine drainage (CMD) are an integral part of the geochemical setting in mining-impacted streams. The precipitates may be very small, amorphous, and, depending on their chemistry, play a role in the storage and release of alkalinity. To evaluate the potential impact of CMD-solids on alkalinity, we conducted various tests using model and natural solids. Laboratory measurements of alkalinity are operationally defined by a titration to a fixed pH. When the solid-solution mixtures were tested using the standard alkalinity measurement method, no alkalinity could be detected; however, a possible reason for that was that the standard …


Boulders As A Lithologic Control On River And Landscape Response To Tectonic Forcing At The Mendocino Triple Junction, Charles Shobe, Georgina Bennett, Gregory Tucker, Kevin Roback, Scott Miller, Joshua Roering Mar 2021

Boulders As A Lithologic Control On River And Landscape Response To Tectonic Forcing At The Mendocino Triple Junction, Charles Shobe, Georgina Bennett, Gregory Tucker, Kevin Roback, Scott Miller, Joshua Roering

Faculty & Staff Scholarship

Constraining Earth’s sediment mass balance over geologic time requires a quantitative understanding of how landscapes respond to transient tectonic perturbations. However, the mechanisms by which bedrock lithology governs landscape response remain poorly understood. Rock type influences the size of sediment delivered to river channels, which controls how efficiently rivers respond to tectonic forcing. The Mendocino triple junction region of northern California, USA, is one landscape in which large boulders, delivered by hillslope failures to channels, may alter the pace of landscape response to a pulse of rock uplift. Boulders frequently delivered by earthflows in one lithology, the Franciscan mélange, have …


Variations In Produced Water Chemistry And Relation To Regional Geology And Production In The Marcellus Shale, Northcentral West Virginia, Jonathan M. Brady Jan 2021

Variations In Produced Water Chemistry And Relation To Regional Geology And Production In The Marcellus Shale, Northcentral West Virginia, Jonathan M. Brady

Graduate Theses, Dissertations, and Problem Reports

An investigation of 74 Marcellus Shale wells across northcentral West Virginia indicates changes in produced water chemistry and quantity can be related to geologic conditions based on well logs and core data. These changes are determined by reviewing multiple produced water analyses for individual wells for periods up to ten years. Results show variations among the areas in this study. From west to east across central Harrison County to central Taylor County, then north into Monongalia County, gamma-ray logs show increasing intensity, especially in the middle and lower Marcellus. XRD mineralogy from core data shows increasing clay content from west …


Independent, Semi-Automated Classification Of Petrographic Features In Volcanic Rocks Using Fiji And Weka, Holly Danielle Pettus Jan 2021

Independent, Semi-Automated Classification Of Petrographic Features In Volcanic Rocks Using Fiji And Weka, Holly Danielle Pettus

Graduate Theses, Dissertations, and Problem Reports

Traditional methods of collecting quantitative petrographic data from thin sections (modal mineralogy, size distribution, shapes, etc.) are time- and labor-intensive, and rarely have sample sizes adequate to statistically describe complex rocks (i.e. volcanic rocks). Although manual counting and measurements are now routinely supplemented by digital image analysis, the majority of quantitative petrographic studies still go through a manual digitization stage where object classes are traced before further analyses. This is a major rate-limiting step that reproduces the same problems of small n-values resulting from significant effort. We have valuated the potential and limitations of using the Trainable Weka Segmentation (TWS) …


Reservoir Characteristics And Lateral Variability Of The Marcellus Formation At The Allegheny Mountain Front, Bruno J. Abersold Jan 2021

Reservoir Characteristics And Lateral Variability Of The Marcellus Formation At The Allegheny Mountain Front, Bruno J. Abersold

Graduate Theses, Dissertations, and Problem Reports

The Marcellus Formation, a large shale gas reservoir located within in the Appalachian basin, produces the energy that fuels the economy across the United States. Well data and rock core for the Coastal 1H well, found in Fayette County, Pennsylvania, provides the basis to understand reservoir characteristics and depositional processes of the Marcellus Formation across the basin. The well is located near along the eastern edge of the productive fairway and adjacent to the Allegheny mountain front. We used characteristics, such as total organic carbon (TOC), geomechanical properties, and lithology, to integrate with ten other available wells across the basin. …


Application Of 3d Seismic Signal And Geomechanical Attributes For Subsurface Fracture Characterization: A Case Study In Clearfield County, Central Pennsylvania, Iman F. Zulkapeli Jan 2021

Application Of 3d Seismic Signal And Geomechanical Attributes For Subsurface Fracture Characterization: A Case Study In Clearfield County, Central Pennsylvania, Iman F. Zulkapeli

Graduate Theses, Dissertations, and Problem Reports

Hydrocarbon exploration in unconventional reservoirs is highly risky due to the nature of the reservoirs and the variability in fractures and reservoir geomechanical properties in the subsurface. The reservoir needs to be fully characterized to avoid any complication such as frac hit, wellbore failure, blowout, or even a dry hole. The Clearfield reservoir produces an exceptionally low amount of gas, compared to the neighboring region in the proximity, which has been poorly understood. This raises the question as to what causes the reservoir to have low productivity.

This study focuses on the natural fracture characterization using high-quality 3D seismic signal …


Refining The Sedimentology And Geochemistry Of The Mid-Permian Blaine Formation Of The Rebecca K. Bounds Core From Greeley County, Kansas, Brigitte Petras Jan 2021

Refining The Sedimentology And Geochemistry Of The Mid-Permian Blaine Formation Of The Rebecca K. Bounds Core From Greeley County, Kansas, Brigitte Petras

Graduate Theses, Dissertations, and Problem Reports

Red siliciclastics and evaporites of Permian Nippewalla Group in mid-continental US were deposited in western equatorial Pangea. Previous studies of these rocks record Permian air temperatures as high as 73 °C, saline lake waters with a pH as low as ~1, and sedimentology that shows arid conditions. This current study conducts detailed sedimentological observations and geochemical analyses of the Blaine Formation of the Nippewalla Group. The Rebecca K. Bounds core from west-central Kansas is used to interpret the depositional environments and diagenetic history of the Blaine Formation.

The lithologies of the Blaine Formation, listed in order of most to least …


Effect Of Oxidative Breakers On Organic Matter Degradation, Contaminant Mobility And Critical Mineral Release During Shale-Fracturing Fluid Interactions In The Marcellus Shale, Shaun Donmoyer Jan 2021

Effect Of Oxidative Breakers On Organic Matter Degradation, Contaminant Mobility And Critical Mineral Release During Shale-Fracturing Fluid Interactions In The Marcellus Shale, Shaun Donmoyer

Graduate Theses, Dissertations, and Problem Reports

Production of oil and gas from organic-rich shale formations has become viable through advancements in multi-stage hydraulic fracturing. The decline of shale gas production after the initial days of fracturing operations coupled with falling oil and gas prices, has pushed industry operators to use new chemical additives as an attempt to increase hydrocarbon production. The implementation of highly reactive fracturing fluids that include strong oxidizing agents, pose as a potential solution to increase well productivity. Strong oxidizing chemicals commonly known in fracturing operations as breakers, are used to improve the viscosity of gel-based fluids after the proppant is transported into …


Regional Correlation And Depositional History Using Well Log And Core Data Of The Middle Devonian Marcellus Poseidon 8m Well, Westmoreland County, Pennsylvania, Usa, Emily R. Jackson Jan 2021

Regional Correlation And Depositional History Using Well Log And Core Data Of The Middle Devonian Marcellus Poseidon 8m Well, Westmoreland County, Pennsylvania, Usa, Emily R. Jackson

Graduate Theses, Dissertations, and Problem Reports

The Marcellus Shale is the largest natural gas producing formation in the Appalachian basin, and as such, presents a unique opportunity for continued research on an area that is critical to meeting the energy needs of the current society. Although the Marcellus has historically been extensively researched, acquisition of well log and core data from the Marcellus Poseidon 8M well in Westmoreland County, PA, allows for application of a new method of data integration, which was utilized in this project to specifically understand the depositional environment and create a correlation with other study wells throughout the basin. This integration was …


Petrographic And Core Analysis Of The Jurassic Norphlet Formation: A Case Study In The Lithofacies Control Of Diagenesis And Porosity In The Flomaton Field, Al, Jarrett Thomas Smith Jan 2021

Petrographic And Core Analysis Of The Jurassic Norphlet Formation: A Case Study In The Lithofacies Control Of Diagenesis And Porosity In The Flomaton Field, Al, Jarrett Thomas Smith

Graduate Theses, Dissertations, and Problem Reports

This study includes a sedimentologic and petrographic study of cores and thin-sections from the Jurassic Norphlet Formation in the Flomaton Field in southern Alabama to define a specific paragenetic history of each facies encountered and to identify key controls on reservoir quality. Eolian dune, nearshore, sand flat, and wadi facies were likely encountered in Norphlet core and thin-section samples that displayed a high degree of heterogeneity between them in terms of porosity, grain contacts, cement abundance/type, intergranular volume, and overall diagenetic processes. These distinct petrographic differences suggest that the paragenesis in the Flomaton Field is primarily facies controlled. The eolian …


A Snapshot Of Ancient Microbial Life: Microorganisms And Organic Compounds In Primary Fluid Inclusions In Bedded Halite, Neoproterozoic Browne Formation Of Central Australia, Sara I. Schreder-Gomes Jan 2021

A Snapshot Of Ancient Microbial Life: Microorganisms And Organic Compounds In Primary Fluid Inclusions In Bedded Halite, Neoproterozoic Browne Formation Of Central Australia, Sara I. Schreder-Gomes

Graduate Theses, Dissertations, and Problem Reports

Modern shallow brine environments contain an abundance of microorganisms. Microorganisms, mineral crystals, and air bubbles can be trapped with those brines in primary fluid inclusions in bedded halite as it grows in shallow saline surface waters. Primary fluid inclusions and their contents can be preserved, unaltered, for millions of years.

The ~830 million-year-old Browne Formation of central Australia contains intervals of bedded halite with unaltered primary fluid inclusions. Intervals of bedded halite were sampled in the Empress 1A core from ~1480 m – 1520 m depths. Here, I used petrography to describe suspect microorganisms and organic compounds that were trapped …


The Fold Illusion: The Origins And Implications Of Ogives On Silicic Lavas, Graham Dm Andrews, Stuart Kenderes, Alan Whittington, Shelby L. Isom, Sarah Brown, Holly Danielle Pettus, Brenna Cole, Kailee Gokey Nov 2020

The Fold Illusion: The Origins And Implications Of Ogives On Silicic Lavas, Graham Dm Andrews, Stuart Kenderes, Alan Whittington, Shelby L. Isom, Sarah Brown, Holly Danielle Pettus, Brenna Cole, Kailee Gokey

Faculty & Staff Scholarship

Folds on the surfaces of mafic lavas are among the most readily recognized geological structures and are used as first-order criteria for identifying ancient lavas on Earth and other planetary bodies. However, the presence of surface-folds on the surface of silicic lavas is contested in this study and we challenge the widely accepted interpretation that silicic lava surfaces contain folds using examples from the western United States and Sardinia, Italy. We interpret the ridges and troughs on their upper surfaces, typically referred to as ‘ogives’ or ‘pressure ridges’, as fracture-bound structures rather than folds. We report on the absence of …


Teaching With Digital 3d Models Of Minerals And Rocks, Graham Dm Andrews, Gabrielle Labishak, Sarah Brown, Shelby L. Isom, Holly Danielle Pettus, Trevor Byers Oct 2020

Teaching With Digital 3d Models Of Minerals And Rocks, Graham Dm Andrews, Gabrielle Labishak, Sarah Brown, Shelby L. Isom, Holly Danielle Pettus, Trevor Byers

Faculty & Staff Scholarship

The disruption to geoscience curricula due to the COVID-19 pandemic highlights the difficulty of making mineral and rock samples accessible to students online rather than through traditional lab classes. In spring 2020, our community had to adapt rapidly to remote instruction; this transition amplified existing disparities in access to geoscience education but can be a catalyst to increase accessibility and flexibility in instruction permanently. Fortunately, a rich collection of 3D mineral and rock samples is being generated by a community of digital modelers (e.g., Perkins et al., 2019).


Volcanic Record Of The Arc-To-Rift Transition Onshore Of The Guaymas Basin In The Santa Rosalía Area, Gulf Of California, Baja California, Graham Dm Andrews Aug 2020

Volcanic Record Of The Arc-To-Rift Transition Onshore Of The Guaymas Basin In The Santa Rosalía Area, Gulf Of California, Baja California, Graham Dm Andrews

Faculty & Staff Scholarship

The Gulf of California is an archetype of continental rupture through transtensional rifting, and exploitation of a thermally weakened arc to produce a rift. Volcanic rocks of central Baja California record the transition from calcalkaline arc magmatism, due to subduction of the Farallon plate (ca. 24–12 Ma), to rift magmatism, related to the opening of the Gulf of California (<12 Ma). In addition, a suite of postsubduction rocks (<12 Ma), referred to as “bajaites,” are enriched in light rare-earth and other incompatible elements (e.g., Ba and Sr). These are further subdivided into high-magnesian andesite (with 50%–58% SiO2 and MgO >4%) and adakite (>56% SiO2 and MgO <3%). The bajaites correlate spatially with a fossil slab imaged under central Baja and are inferred to record postsubduction melting of the slab and subduction-modified mantle by asthenospheric upwelling associated with rifting or slab breakoff. We report on volcanic rocks of all three suites, which surround and underlie the Santa Rosalía sedimentary rift basin. This area represents the western margin of the Guaymas basin, the most magmatically robust segment of the Gulf of California rift, where seafloor spreading occurred in isolation for 3–4 m.y. (starting at 6 Ma) before transtensional pull-apart basins to the north and south ruptured the continental crust. Outcrops of the Santa Rosalía area thus offer the opportunity to understand the magmatic evolution of the Guaymas rift, which has been the focus of numerous oceanographic expeditions.

We describe 21 distinct volcanic and hypabyssal map units in the Santa Rosalía area, using field characteristics, petrographic data, and major- and trace-element geochemical data, as well as zircon isotopic data and …


Paleohydrology And Machine-Assisted Estimation Of Paleogeomorphology Of Fluvial Channels Of The Lower Middle Pennsylvanian Allegheny Formation, Birch River, Wv, Oluwasegun O. Abatan, Amy Weislogel Jan 2020

Paleohydrology And Machine-Assisted Estimation Of Paleogeomorphology Of Fluvial Channels Of The Lower Middle Pennsylvanian Allegheny Formation, Birch River, Wv, Oluwasegun O. Abatan, Amy Weislogel

Faculty & Staff Scholarship

Rivers transport sediments in a source to sink system while responding to allogenic controls of the depositional system. Stacked fluvial sandstones of the Middle Pennsylvanian (Desmoinesian Stage, ∼310–306 Ma) Allegheny Formation (MPAF) exposed at Birch River, West Virginia exhibit change in sedimentary structure and depositional style, reflecting changes in allogenic behavior. Paleohydrologic and numerical analysis were used to quantify geomorphological and paleohydrologic variations reflected by MPAF fluvial deposits with the goal of understanding the controls on resulting fluvial sandstone architecture in these different systems. Channel body geometry, sedimentary structures, and sandstone grain size distribution were used to reconstruct the paleoslope …