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2017

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Articles 331 - 360 of 437

Full-Text Articles in Geology

2016 Nebraska Water Leaders Academy - Final Report, Mark E. Burbach, Connie Reimers-Hild Jan 2017

2016 Nebraska Water Leaders Academy - Final Report, Mark E. Burbach, Connie Reimers-Hild

Conservation and Survey Division: Faculty and Staff Publications

The effective management of Nebraska’s water resources is evermore challenged by variations in weather, climate, technology, socioeconomic policies, and regulation. Anthropogenic climate change, declining water tables and stream flows, increasing demands on freshwater, aging water infrastructure, fiscal constraints, and impacts on aquatic organisms are particularly imminent challenges in Nebraska and around the world (Pahl-Wostl et al., 2013; Pittock et al., 2008; USACE, 2010). Sustaining freshwater ecosystem services in the face of emerging environmental threats presents an immense societal dilemma worldwide (Pittock et al., 2013; Rockström et al., 2009, Millenium Ecosystem Assessment, 2005). The rapidly changing conditions of water resources in …


Sequence Stratigraphic And Tectono-Stratigraphic Successions, Ozark Shelf, Tri-State Region, Southern Midcontinent, E. C. Bello Jan 2017

Sequence Stratigraphic And Tectono-Stratigraphic Successions, Ozark Shelf, Tri-State Region, Southern Midcontinent, E. C. Bello

Journal of the Arkansas Academy of Science

The southern Ozark region, Arkansas, Missouri, and Oklahoma occupies the southern border of the North American craton. Its sedimentary succession preserves a complete Wilson Cycle reflecting the Late Precambrian-Cambrian rifting of Rodinia into the Laurussian and Gondwanan landmasses that opened the Iapetus Ocean Basin during the Late Cambrian-Middle Mississippian. The basin was closed during the Late Mississippian-Middle Pennsylvanian by the collision of Laurussia with Gondwana. During the Late Cambrian through the Middle Pennsylvanian, the Ozark Shelf, including its gently sloping, Northern Arkansas Structural Platform (NASP) and adjacent ramp, records both transgression and regression by epeiric seas as well as regional …


Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan Jan 2017

Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan

Cal Poly Humboldt theses and projects

The Pullen and Saint George formations are coeval late Miocene-early Pliocene sedimentary formations in northwestern California. The type localities of both formations were studied from a micropaleontologic perspective that focused primarily on Foraminifera, but with additional observations of other fossil groups to reconstruct their past depositional environments. The results obtained in this study provided a photomicrographic inventory of the microfossils from both formations, aided in investigating changes in paleobathymetry of the formations during the late Miocene and early Pliocene based on Foraminifera, and allowed for interpretation of paleoecological signals from the foraminiferan associations. Foraminifera have not been previously described in …


Structural Analysis Of A Triangle Zone Culmination, Comb Rock, Lewis And Clark County, Montana, Shane S. Fussell Jan 2017

Structural Analysis Of A Triangle Zone Culmination, Comb Rock, Lewis And Clark County, Montana, Shane S. Fussell

Graduate Student Theses, Dissertations, & Professional Papers

A triangle zone is a structure commonly found at the leading edge of a thrust belt, characterized by a triangular cross-section of thrust faults. In the Montana triangle zone, west-dipping thrust faults intersect east-dipping ones above a regional detachment fault. Most studies of triangle zones focus on the structure in a cross-sectional sense, but little work addresses variations along the trend. The Canadian Rocky Mountain triangle zone has long been a productive petroleum province, so understanding the southern extent of this zone, where it enters Montana, is of interest for economic purposes as well as geologic understanding. Previous studies have …


Lateral Heterogeneity And Architectural Analysis Of The Wall Creek Member Of The Upper Cretaceous (Turonian) Frontier Formation, John Zupanic Jan 2017

Lateral Heterogeneity And Architectural Analysis Of The Wall Creek Member Of The Upper Cretaceous (Turonian) Frontier Formation, John Zupanic

Graduate Student Theses, Dissertations, & Professional Papers

The Upper Turonian Wall Creek Member (WCM) of the Frontier Formation is part of a series of marine sandstones that were deposited on the western flank of the Cretaceous Western Interior Seaway (KWIS). The KWIS was a low accommodation shallow-marine foreland basin system that included many large deltaic complexes on its western margin. Deposition of WCM deltaic deposits was strongly influenced by fourthorder glacioeustatic cycles, oceanographic circulation patterns, and tectonics related to the active Sevier fold and thrust belt to the west. An in-depth field study of the WCM was performed on the western flank of the Powder River Basin …


Kentucky Stratigraphy With Stage Correlations, Stephen F. Greb Jan 2017

Kentucky Stratigraphy With Stage Correlations, Stephen F. Greb

Map and Chart--KGS

No abstract provided.


Field Investigation Of An Active Landslide In Kentucky: A Framework To Correlate Electrical Data And Shear Strength, Matthew M. Crawford, L. Sebastian Bryson Jan 2017

Field Investigation Of An Active Landslide In Kentucky: A Framework To Correlate Electrical Data And Shear Strength, Matthew M. Crawford, L. Sebastian Bryson

Report of Investigations--KGS

Landslide hazard assessments are best accomplished by a multidisciplinary approach that connects geologic processes with geotechnical behavior. Tools to accomplish this in the field include geologic characterization, hydrologic monitoring, and geophysical surveys, and in the laboratory, soil-strength testing. Volumetric water content, soil-water potential (suction), local rainfall, and in situ electrical conductivity were measured at a shallow colluvial landslide in Kentucky. Surface electrical-resistivity surveys were also conducted to support interpretations of depth to failure, lithologic differences, and changes in moisture content over time. Correlations of hydrologic data with electrical measurements and shear strength indicate that observed changes in the degree of …


America's National Parks And The Anthropocene: Addressing The Present To Accommodate The Future In Acadia National Park, Sophie A. Swetz Jan 2017

America's National Parks And The Anthropocene: Addressing The Present To Accommodate The Future In Acadia National Park, Sophie A. Swetz

Honors Theses

In 2000, atmospheric chemist, Paul J. Crutzen, and limnologist, Eugene Stoermer, formally proposed the idea of “the Anthropocene,” a new geologic epoch in which humans are the dominant force shaping the Earth. To claim the Anthropocene's existence is to declare that human actions have altered the Earth in such a way that geologic indicators render it a distinct epoch in the stratification of geologic time. This new epoch emerges as a consequence of increased technological development employed to accommodate an anthropocentric human existence. That is, rapid advancements in technology have driven the transformation from a primarily naturally controlled planet to …


Upper Water Structure And Mixed Layer Depth In Tropical Waters: The Seats Station In The Northern South China Sea, Jen-Hua Tai, George T. F. Wong, Xiaoju Pan Jan 2017

Upper Water Structure And Mixed Layer Depth In Tropical Waters: The Seats Station In The Northern South China Sea, Jen-Hua Tai, George T. F. Wong, Xiaoju Pan

OES Faculty Publications

The variability of the upper water hydrographic structure, the efficacy of the different schemes for estimating the mixed layer depth (MLD), the inter-comparability estimation of the MLDs and diurnal and intra-annual MLD climatology in the tropical waters in the northern South China Sea were accessed in 702 depth-profiles of potential temperature (θ) and salinity collected in 64 cruises between 17.5 and 18.5°N and 115.3 and 116.3°E from 1997 to 2013. The hydrographic structure may be subdivided into three principal types: the classical type, with quasi-isopycnal surface mixed layer followed by an abrupt increase in the depth-gradient in θ and potential …


Holocene Cyclic Records Of Ice-Rafted Debris And Sea Ice Variations On The East Greenland And Northwest Iceland Margins, D. A. Darby, J. T. Andrews, S. T. Belt, A. E. Jennings, P. Cabedo-Sanz Jan 2017

Holocene Cyclic Records Of Ice-Rafted Debris And Sea Ice Variations On The East Greenland And Northwest Iceland Margins, D. A. Darby, J. T. Andrews, S. T. Belt, A. E. Jennings, P. Cabedo-Sanz

OES Faculty Publications

The dynamics of the Greenland Ice Sheet and drift of sea ice from the Arctic Ocean reaching Denmark Strait are poorly constrained. We present data on the provenance of Fe oxide detrital grains from two cores in the Denmark Strait area and compare the Fe grain source data with other environmental proxies in order to document the variations and potential periodicities in ice-rafted debris delivery during the Holocene. Based on their Fe grain geochemistry, the sediments can be traced to East Greenland sources and to more distal sites around the Arctic Basin. On the Holocene time scales of the two …


Constraining Boundaries And Extent Of The Charleston Uplift, Northeast New Madrid Seismic Zone, Using Shallow Seismic Reflection Methods, Clara Rose Rucker Jan 2017

Constraining Boundaries And Extent Of The Charleston Uplift, Northeast New Madrid Seismic Zone, Using Shallow Seismic Reflection Methods, Clara Rose Rucker

Theses and Dissertations--Earth and Environmental Sciences

A recently identified 30 km by 7.2 km subsurface stratigraphic uplift, called the Charleston uplift, exhibits 36 m offset of Paleogene-Quaternary unconformity based on shallow borehole data. Two seismic soundings demonstrated relief in Paleozoic and Cretaceous reflectors across the northern boundary of the uplift, suggesting a structural origin rather than an erosional origin. This study collected and analyzed 18 additional shallow seismic soundings to confirm Paleozoic and Cretaceous offset across the boundaries of the uplift, to better constrain the surface trace of the uplift, and to examine potential extension into western Kentucky. One ground penetrating radar profile was taken in …


Hydrogeochemical Controls On Reactive And Nonreactive Solute Transport In Heterogenous Porous Media, Mahta Gholizadeh Ansari Jan 2017

Hydrogeochemical Controls On Reactive And Nonreactive Solute Transport In Heterogenous Porous Media, Mahta Gholizadeh Ansari

Masters Theses

"This work examines how physical and chemical heterogeneity can affect reactive and non-reactive transport in porous media. The effect of heterogeneity of the porous media is investigated both on dissolution rate of magnesite and attenuation time of nonreactive contaminants in non-reactive media. Various spatial distribution were created using statistical parameters in PETREL.A total of 6793 transport modeling simulations were run using CrunchFlow. Lasso regression was used to select most significant features and those features are then used in linear regression and deep learning models.

The magnesite dissolution simulations were performed under different permeability ratios (magnesite /sand permeability) and inlet pH. …


Comparison Of Acoustic Recorders And Field Observers For Monitoring Tundra Bird Communities, Skyler T. Vold, Colleen M. Handel, Lance B. Mcnew Jan 2017

Comparison Of Acoustic Recorders And Field Observers For Monitoring Tundra Bird Communities, Skyler T. Vold, Colleen M. Handel, Lance B. Mcnew

United States Geological Survey: Staff Publications

Acoustic recorders can be useful for studying bird populations but their efficiency and accuracy should be assessed in pertinent ecological settings before use. We investigated the utility of an acoustic recorder formonitoring abundance of tundra-breeding birds relative to point-count surveys in northwestern Alaska, USA, during 2014. Our objectives were to 1) compare numbers of birds and species detected by a field observer with those detected simultaneously by an acoustic recorder; 2) evaluate how detection probabilities for the observer and acoustic recorder varied with distance of birds from the survey point; and 3) evaluate whether avian guild-specific detection rates differed between …


The Aerosphere As A Network Connector Of Organisms And Their Diseases, Jeremy D. Ross, Eli S. Bridge, Diann J. Prosser, John Y. Takekawa Jan 2017

The Aerosphere As A Network Connector Of Organisms And Their Diseases, Jeremy D. Ross, Eli S. Bridge, Diann J. Prosser, John Y. Takekawa

United States Geological Survey: Staff Publications

Aeroecological processes, especially powered flight of animals, can rapidly connect biological communities across the globe. This can have profound consequences for evolutionary diversification, energy and nutrient transfers, and the spread of infectious diseases. The latter is of particular consequence for human populations, since migratory birds are known to host diseases which have a history of transmission into domestic poultry or even jumping to human hosts. In this chapter, we present a scenario under which a highly pathogenic avian influenza (HPAI) strain enters North America from East Asia via postmolting waterfowl migration. We use an agent-based model (ABM) to simulate the …


Co2 Adsorption On Volcanic Ash: Net Contribution Of Volcanic Eruptions To The Global Carbon Cycle, Lee New Jan 2017

Co2 Adsorption On Volcanic Ash: Net Contribution Of Volcanic Eruptions To The Global Carbon Cycle, Lee New

Electronic Theses and Dissertations

Adsorption of co2 on mineral surfaces accounts for a small percentage of the terrestrial co2 sink. Volcanic ash is virtually free of co2 when erupted and has a high surface area resulting in a high capacity for co2 adsorption. Volcanism is commonly assumed to be only a source of co2, but pyroclastic eruptions can also potentially serve as a sink. Adsorption was investigated for 6 volcanic ash samples of andesitic composition from four volcanoes: Okmok, Redoubt, Spurr, and Tungurahua. The eruption of volcano redoubt released 0.75 x 109 metric tons of co2 and 55 x 109 kg of ash throughout …


Detection Of Sedimentary Depositional Cycles In The Salado Formation, Southeastern New Mexico, Scott Paul Milo Jan 2017

Detection Of Sedimentary Depositional Cycles In The Salado Formation, Southeastern New Mexico, Scott Paul Milo

Electronic Theses and Dissertations

An abundance of evaporitic features is preserved throughout the approximately 2,000-foot-thick Salado formation that is present across west Texas and southeastern New Mexico. The formation and preservation of evaporitic features are largely influenced by hydrology, and so those found in the Salado represent an uninterrupted record of hydrogeologic conditions in what is now the southwestern United States during the late Permian. Because it is home to the Waste Isolation Pilot Plant (WIPP) repository chamber, the salado has been the subject of countless studies ranging from areas of sedimentology, to geochemistry, to geotechnical engineering, to hydrology. However, until now there have …


Seismic Anisotropy As A Function Of Mineralogy And Rock Type In Chester Gneiss Dome, Southeast Vermont, Brittany Watling Jan 2017

Seismic Anisotropy As A Function Of Mineralogy And Rock Type In Chester Gneiss Dome, Southeast Vermont, Brittany Watling

Wayne State University Theses

Our knowledge of composition and structure in middle and lower crustal rocks is limited due to restricted accessibility, and thus comes mainly from studies of seismic velocities. But isotropic seismic velocities are not sufficient to distinguish between the many possible rock types in the middle and lower crust. Seismic anisotropy is the directional dependence of seismic velocity, and may provide further constraints on mineralogy and rock type. This study is focused on characterizing the seismic anisotropy of rocks from the Chester dome in southeast Vermont. We have simplified the Chester dome rock types into four groups based on rock type …


Kentucky Stratigraphy, Stephen F. Greb Jan 2017

Kentucky Stratigraphy, Stephen F. Greb

Map and Chart--KGS

No abstract provided.


Depositional Controls And Sequence Stratigraphy Of Lacustrine To Marine Transgressive Deposits In A Rift Basin, Lower Cretaceous Bluff Mesa, Indio Mountains, West Texas, Andrew Anderson Jan 2017

Depositional Controls And Sequence Stratigraphy Of Lacustrine To Marine Transgressive Deposits In A Rift Basin, Lower Cretaceous Bluff Mesa, Indio Mountains, West Texas, Andrew Anderson

Open Access Theses & Dissertations

Successful hydrocarbon exploration in former rift basins of the South Atlantic pre-salt has generated interest in understanding depositional, diagenetic, and stratigraphic controls on pre-salt deposits. However, most studies to date have focused on attributes and controls on presalt lacustrine carbonate reservoir systems and little work has been done on the overlying marine sealing facies. Currently our standard sequence stratigraphic model of marine transgression of rift systems involves a single pulse of marine flooding over fluvially-incised valleys resulting in backstepping of fluvial and estuarine siliciclastic facies within the erosionally confined zone of an incised valley. However, the pre-salt systems of the …


Gypsum, Calcite, And Dolomite Caprock Fabrics And Geochemistry From The Gypsum Valley Salt Diapir, Paradox Basin, Southwestern Colorado, Kevin Lerer Jan 2017

Gypsum, Calcite, And Dolomite Caprock Fabrics And Geochemistry From The Gypsum Valley Salt Diapir, Paradox Basin, Southwestern Colorado, Kevin Lerer

Open Access Theses & Dissertations

Caprocks are found on top of or in a lateral position relative to salt diapirs. The caprocks predominantly comprise sulfate minerals such as anhydrite or gypsum, which presumably accreted during the dissolution of salt from evaporite sediments. In some cases, the sulfate minerals are replaced by carbonate minerals, referred to as "carbonate caprock". Carbonate caprocks associated with salt diapirs are important because they can act as reservoirs or conduits for hydrocarbons, and because they can be easily misidentified as carbonate lithologies belonging to the stratigraphy of the sedimentary sequences adjacent to the diapir, which can jeopardize the accurate interpretation of …


Genesis Of Unique Carbonate Fans In A Pre-Salt Reservoir Analogue, Indio Mountains, West Texas, Andre Llanos Jan 2017

Genesis Of Unique Carbonate Fans In A Pre-Salt Reservoir Analogue, Indio Mountains, West Texas, Andre Llanos

Open Access Theses & Dissertations

Hydrocarbon exploration in pre-salt sediments of rift basins on the South Atlantic Margin have proven to be successful major oil plays. Located on the western margin of the rift, the Brazilian pre-salt reservoirs of the Santos, Campos, and Espirito Santo Basins are hosted by lacustrine/marine-influenced carbonates that comprise laterally extensive, laminated microbialite facies. The Indio Mountains, located in West Texas, provide well-exposed outcrops of Lower Cretaceous marine and non-marine rift basin strata that can be considered a reservoir-analog to the South Atlantic Margin pre-salt facies. Of particular interest for hydrocarbon exploration are unique carbonate features that have been discovered in …


Nebraska Statewide Groundwater-Level Monitoring Report 2016, Aaron R. Young, Mark E. Burbach, Leslie M. Howard, Michele M. Waszgis, R. Matthew Joeckel, Sue Olafsen Lackey Jan 2017

Nebraska Statewide Groundwater-Level Monitoring Report 2016, Aaron R. Young, Mark E. Burbach, Leslie M. Howard, Michele M. Waszgis, R. Matthew Joeckel, Sue Olafsen Lackey

Conservation and Survey Division: Faculty and Staff Publications

The term “groundwater” has come to be all but synonymous with Nebraska. Nearly three-quarters of the volume of the High Plains aquifer lies beneath the State, and groundwater maintains our streams, our ecosystems, our people, and our vitally important agricultural economy. Although Nebraska’s total groundwater resource is vast, it is also quite vulnerable to changes induced by natural processes and by humankind, necessitating a long-term commitment to wise management through informed decision making. Monitoring, studying, and reporting are the essential basis for such management and, ultimately, for meeting the myriad challenges presented by change.

The personnel of the Conservation and …


The Oligocene West Elk Breccia: Evidence For Massive Volcanic Debris Avalanches In The Eastern Gunnison River Valley, West-Central Colorado, U.S.A., Patrick J. Whalen Jan 2017

The Oligocene West Elk Breccia: Evidence For Massive Volcanic Debris Avalanches In The Eastern Gunnison River Valley, West-Central Colorado, U.S.A., Patrick J. Whalen

Theses and Dissertations--Earth and Environmental Sciences

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common …


Initial Microseismic Recordings At The Onset Of Unconventional Hydrocarbon Development In The Rome Trough, Eastern Kentucky, Andrew Holcomb Jan 2017

Initial Microseismic Recordings At The Onset Of Unconventional Hydrocarbon Development In The Rome Trough, Eastern Kentucky, Andrew Holcomb

Theses and Dissertations--Earth and Environmental Sciences

The Cambrian Rogersville Shale is a part of a hydrocarbon system in the Rome Trough of eastern Kentucky and West Virginia that can only be produced unconventionally. In Kentucky, the Rogersville Shale ranges in depth from ~1,800 to ~3,700 m below the surface with the crystalline basement ~1,000 m lower than the formation’s base. Baseline Rome Trough microseismicity data were collected, focusing on wastewater injection wells and recently completed and planned unconventional hydrocarbon test wells in the Rogersville Shale, using thirteen broadband seismic stations installed between June, 2015 and June, 2016 and existing University of Kentucky and central and eastern …


Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham Jan 2017

Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham

Theses and Dissertations--Earth and Environmental Sciences

A zone of high magnetization along the SE margin of Paleoproterozoic Laurentia in the United States is indicated by magnetic anomaly data. The SE edge corresponds to the geochemical Neodymium mantle derivation model age (TDM) boundary and the entire anomaly overlies the Paleoproterozoic Mazatzal Province. Two-dimensional gravity and magnetic models across the Nd boundary are created with Moho constrained from receiver functions with gravity, sedimentary thickness and the base of the crustal magnetization. Upper crustal magnetization does not show strong variation across this boundary and much of the strong magnetization appears to lie in the middle crust. Using …


Effects Of Hydrologic Connectivity And Land Use On Floodplain Sediment Accumulation At The Savannah River Site, South Carolina, Jeremy E. Eddy Jan 2017

Effects Of Hydrologic Connectivity And Land Use On Floodplain Sediment Accumulation At The Savannah River Site, South Carolina, Jeremy E. Eddy

Theses and Dissertations--Earth and Environmental Sciences

Floodplains, and the sediment accumulating naturally on them, are important to maintain stream water quality and serve as sinks for organic and inorganic carbon. Newer theories contend that land use and hydrologic connectivity (water-mediated transport of matter, energy, and/or organisms within or between elements of the hydrologic cycle) play important roles in determining sediment accumulation on floodplains. This study hypothesizes that changes in hydrologic connectivity have a greater impact on floodplain sediment accumulation than changes in land use. Nine sediment cores from seven sub-basins were collected from the Savannah River Site (SRS), South Carolina, and processed for grain-size, radionuclide dating …


Utilizing Structure-From-Motion Photogrammetry And Unmanned Aerial Vehicles To Characterize Variability In Fluvial Deposits From The Salt Wash Member Of The Morrison Formation, East-Central Utah, John Chesley Jan 2017

Utilizing Structure-From-Motion Photogrammetry And Unmanned Aerial Vehicles To Characterize Variability In Fluvial Deposits From The Salt Wash Member Of The Morrison Formation, East-Central Utah, John Chesley

Theses and Dissertations

Modern fluvial systems are highly variable, often containing the entire spectrum of fluvial styles (e.g., braided to meandering). This variability is difficult to capture in ancient fluvial deposits due to limited 1- and 2-dimesional exposures, which provide only a snapshot of the depositional history at one location. As a result, researchers are forced to interpolate between exposures and develop regional scale models that often underestimate the complexity and variability seen in modern environments. Outcrops of the Upper Jurassic Salt Wash Member of the Morrison Formation in east-central Utah, USA provide a relatively unique opportunity to examine ancient fluvial sandstone bodies …


Lake Magadi And The Soda Lake Cycle: A Study Of The Modern Sodium Carbonates And Of Late Pleistocene And Holocene Lacustrine Core Sediments, Emma Mcnulty Jan 2017

Lake Magadi And The Soda Lake Cycle: A Study Of The Modern Sodium Carbonates And Of Late Pleistocene And Holocene Lacustrine Core Sediments, Emma Mcnulty

Graduate Dissertations and Theses

The Magadi Basin, Kenya, within the East African Rift Valley, contains two closed-basin alkaline lakes, Lake Magadi and Nasikie Engida that now precipitate trona (Na2CO3.NaHCO3.2H2O) and nahcolite (NaHCO3). Observations of the conditions of modern trona and nahcolite deposition in the Magadi Basin form the basis of the “soda lake cycle”. This study aims to use the sedimentary structures of the modern sodium carbonates of Lake Magadi as an analogue for similar ancient deposits around the world, including the vast trona and nahcolite deposits of the Eocene Green River Formation. Lake Magadi has been evolving since 1.08 Ma within a well-known …


Imaging Bioturbation In Supratidal Carbonates: Non-Invasive Field Techniques Enhance Neoichnological And Zoogeomorphological Research, San Salvador, The Bahamas, Karen Kopcznski, Ilya Buynevich, H. Allen Curran, Jon Caris, Jonathan Nyquist Jan 2017

Imaging Bioturbation In Supratidal Carbonates: Non-Invasive Field Techniques Enhance Neoichnological And Zoogeomorphological Research, San Salvador, The Bahamas, Karen Kopcznski, Ilya Buynevich, H. Allen Curran, Jon Caris, Jonathan Nyquist

Geosciences: Faculty Publications

A case study in unconsolidated carbonates on San Salvador Island, The Bahamas, utilized high-frequency (800 MHz) georadar imaging to augment existing methodologies (burrow counts and measurements, casting) in brachyuran bioturbation research (Ocypode quadrata and Gecarcinus lateralis), and as part of a new dataset characterizing blue land crab (Cardisoma guanhumi) burrows. Non-invasive techniques such as ground-penetrating radar (GPR) can complement traditional field surveys aimed at quantifying mesoscale bioturbation in modern settings. These methods can establish diagnostic features for tracemaker identification and refine existing ichnofacies models. Drone-mounted aerial coverage provided the first high-resolution images of the micro-topography and …


Glaciovolcanic Megapillows Of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland, Rachel Heineman Jan 2017

Glaciovolcanic Megapillows Of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland, Rachel Heineman

Honors Papers

At Undirhliðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring throughout this area demonstrate their role in the multi-stage construction of the ridge modeled by Pollock et al. (2014). The outcrops exhibit radial jointing, bands of vesicles and glassy rims, they occur in high relief surrounded by basalt breccia resembling pillow rubble, and are composed of plagioclase-phyric olivine basalt with plagioclase-rich groundmass. They occur in multiple pillow lava units …