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Theses/Dissertations

Geology

2011

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Articles 31 - 60 of 157

Full-Text Articles in Physical Sciences and Mathematics

Risks Posed To Drinking Water Aquifers Due To Leakage Of Dissolved Co2 In Improperly Abandoned Wellbores, Kirk Ellison Aug 2011

Risks Posed To Drinking Water Aquifers Due To Leakage Of Dissolved Co2 In Improperly Abandoned Wellbores, Kirk Ellison

All Theses

In order to ensure safe long-term storage of carbon dioxide in geologic formations, the risks posed by improperly abandoned wells must be understood and minimalized. In addition to supercritical and gaseous CO2, brine containing dissolved CO2 poses a leakage risk. CO2 dissolution in brine leads to denser brine and better long-term storage security, but its leakage risk is not zero. Under specific circumstances with formation overpressure or overlying aquifer drawdown, dissolved brine can flow up improperly abandoned wells where it can potentially enter and contaminate drinking water aquifers. The possibility that depressurization in the wellbore may cause CO2 exsolution from …


Biomarkers In The Lower Huron Shale (Upper Devonain) As Indicators Of Organic Matter Source, Depositional Environment, And Thermal Maturity, John Kroon Aug 2011

Biomarkers In The Lower Huron Shale (Upper Devonain) As Indicators Of Organic Matter Source, Depositional Environment, And Thermal Maturity, John Kroon

All Theses

The Lower Huron Shale (Upper Devonian) is considered the largest shale gas reservoir in the Big Sandy Field in Kentucky and West Virginia. The potential for gas shales, such as the Lower Huron, to produce natural gas is a function of type, amount, and thermal maturation of their organic matter. Twenty-one Lower Huron Shale samples from eight wells located in eastern Kentucky and southern West Virginia were analyzed for biomarker content to interpret biological source of organic matter, depositional environment conditions, and thermal maturity. The following biomarkers were identified: n-alkanes (C15 to C31), pristane (Pr), phytane (Ph), steranes (αααR, (αααS, …


Critical Thresholds For Sediment Mobility In An Urban Stream, Ross H. Martin Aug 2011

Critical Thresholds For Sediment Mobility In An Urban Stream, Ross H. Martin

Geosciences Theses

Bed load transport measurements were made in a small urban stream in Decatur, GA, from which thresholds for motion were calculated using methodologies from the published literature. These methodologies are discussed in terms of their limitations and assumptions. Mobility frequencies were calculated for single grains of each grain size fraction to illustrate the transition from size selective transport to equal mobility. In general, urban streams behave differently than many gravel rivers in non-urban settings because of differences in the availability and character of sediment sources and altered flow hydrographs. This comparison allows for discussion about the way sediment is transported …


Taxonomy And Geochemistry Of The Globigerinoides Ruber-Elongatus Plexus, With Paleontological Implications, Elizabeth Ann Brown Jul 2011

Taxonomy And Geochemistry Of The Globigerinoides Ruber-Elongatus Plexus, With Paleontological Implications, Elizabeth Ann Brown

USF Tampa Graduate Theses and Dissertations

The reliability of foraminifera as stratigraphic index fossils, and as isotopic proxies of marine environments, is based on the assumption that the fossil concepts represent uniform species, responding consistently to their ambient environments. Understanding sources of uncertainty is, therefore, critical. In this dissertation, I explore a potential bias in the application of planktonic foraminifera utilized extensively for Cenozoic paleo-reconstruction and, to a lesser extent, biostratigraphy: the Globigerinoides ruber-elongatus plexus (‘plexus’ meaning a complex network of interconnected members). Taxonomic revisions since 1826 have resulted in the merging of multiple Globigerinoides species names under one general designation (“Globigerinoides ruber”), the implications of …


Mammalian Fauna From The Fullerton Gravel Pit (Ogallala Group, Late Miocene), Morton County, Kansas, Michael Anthony Calvello Jul 2011

Mammalian Fauna From The Fullerton Gravel Pit (Ogallala Group, Late Miocene), Morton County, Kansas, Michael Anthony Calvello

Master's Theses

The Fullerton Gravel Pit, Morton County, Kansas is one of many sites in western Kansas at which the Ogallala Group crops out. The Ogallala Group was deposited primarily by streams flowing from the Rocky Mountains. Evidence of water transport is observable at the Fullerton Gravel Pit through the presence of allochthonous clasts, cross-bedding, pebble alignment, and fossil breakage and subsequent rounding. Fluvial mechanisms also played an important role in the distribution of fossil material. When the fossils from the Fullerton Gravel Pit are placed in Voorhies Groups, it appears that a majority of them were removed from suspension gradually and …


The Complex Paragenetic History Of Basal Negaunee Iron Formation Iron Ores, Tilden Mine, Marquette District, Upper Michigan, Natalie J. Pietrzak Jun 2011

The Complex Paragenetic History Of Basal Negaunee Iron Formation Iron Ores, Tilden Mine, Marquette District, Upper Michigan, Natalie J. Pietrzak

Electronic Thesis and Dissertation Repository

Variable mineral chemistry and textures of basal Negaunee iron ores mined in the Main Tilden Pit have led to metallurgical difficulties. Core-logging and detailed petrography supported by microprobe investigations, identify three upward fining lithofacies within the Main Pit Carbonate and overlying Martite ore domains: 1) Basal Clastics; 2) Medial BIF; and 3) Granular Iron Formation. Growth fault related subsidence controlled deposition of the Basal Clastics, comprised of detrital quartz dispersed in a matrix of chlorite, cemented by ferri-hydrite, chert and Mg-siderite. Subsequent starvation of any clastic input led to cyclic iron-silica precipitation throughout the deposition of Medial BIF. Increasing wave …


Petrologic Evidence For Mafic Recharge At Volcán Barú, Western Panama: Implications For A Late Pleistocene Sector Collapse, Shannon M. Brady Jun 2011

Petrologic Evidence For Mafic Recharge At Volcán Barú, Western Panama: Implications For A Late Pleistocene Sector Collapse, Shannon M. Brady

Honors Theses

The purpose of this study is to gain a better understanding of the petrologic conditions of the magma chamber beneath Volcán Barú in western Panama. Volcán Barú is an andesite stratovolcano that experienced a large sector collapse during the Late Pleistocene, which destabilized the southwestern flank of its edifice. Samples were taken from the cores of hummocks and megaclasts deposited as a result of this sector collapse, which are inferred to have been intact wall rock from the pre-collapse edifice. These samples range in composition from 51.8 to 61.7 wt. % SiO2 and have a geochemical signature that is consistent …


A Continuous Late Holocene Record Of Paleoclimate Change From Grinnell Lake Sediment Cores, Glacier National Park, Montana, Jonathan G. Griffith Jun 2011

A Continuous Late Holocene Record Of Paleoclimate Change From Grinnell Lake Sediment Cores, Glacier National Park, Montana, Jonathan G. Griffith

Honors Theses

Grinnell Lake is a glacially-fed alpine lake in the northern Rocky Mountains of Montana. Limnological parameters and radiocarbon ages from a ~1.17 -meter-long sediment core from Grinnell Lake provide a ~1,200 year-long climate record. The objective of this thesis is to develop a multi-proxy record of glaciation by distinguishing periods of positive and negative mass balance chronologically. Two overlapping sediment cores (1P-1B-1 and 1C-2B-1) were described, photographed, and sampled at 0.5 cm, 1 cm, and 5 cm intervals and analyzed for % organic carbon, % inorganic carbon, mineral composition, bulk density, biogenic silica, and clastic sediment flux. Glacial fluctuations were …


Detrital Zircon Fission Track Ages Of The Paleocene Orca Group Of Eastern Prince William Sound Near Cordova Alaska, Tyler M. Izykowski Jun 2011

Detrital Zircon Fission Track Ages Of The Paleocene Orca Group Of Eastern Prince William Sound Near Cordova Alaska, Tyler M. Izykowski

Honors Theses

The Prince William terrane is a major component of the Mesozoic-Tertiary accretionary complex of the North American Cordillera that is well exposed for ~2200 km in southern Alaska and is inferred to be one of the thickest accretionary complexes in the world. Detrital zircons from Prince William terrane record the thermal evolution and exhumation history of the accretionary wedge. Samples of the Paleocene-Eocene Orca Group of the Prince William terrane were analyzed using detrital zircon fission track techniques to understand the thermochronology of the region near Cordova. Six sandstones from the Orca Group and one sample of the Sheep Bay …


Geochemical And Petrographic Analysis Of Gore Mountain Garnets, Adirondacks Ny, Elizabeth R. Morgan Jun 2011

Geochemical And Petrographic Analysis Of Gore Mountain Garnets, Adirondacks Ny, Elizabeth R. Morgan

Honors Theses

The mine at Gore Mountain is famous for its giant garnets and long history of garnet abrasive production. This location, Warrensburg (Wall St.), and others were examined to attempt to better understand the petrogenesis of these remarkable rocks. Our studies have emphasized the geochemistry of bulk rocks and rock and mineral separates (122 analyses), thin section petrology, and thermodynamic modeling of mineral assemblages. At Gore Mtn. the ore has the assemblage hornblende-plagioclase-garnet-OPX-biotite, and formed over a ~2 m thick transition zone from a layered olivine corona gabbro, metamorphosed at granulite facies. Petrographically the delicate corona structures and fine-grained garnets were …


The Impact Of Modern Weathering On The Geochemistry Of A Marine Permo-Triassic Boundary Section, Jeremy Christopher Williams Jun 2011

The Impact Of Modern Weathering On The Geochemistry Of A Marine Permo-Triassic Boundary Section, Jeremy Christopher Williams

Graduate Masters Theses

The Permian-Triassic Boundary (PTB) marks the end-Permian extinction, the greatest mass extinction recorded in Earth's history. The Attargoo PTB section located in Spiti Valley, Himachal Pradesh, India was situated along the north continental margin of Gondwana-land in the Neo-Tethys Ocean during the end-Permian extinction. In Spiti Valley, PTB sections such as Attargoo are exposed by a thin (~ 2cm) ferruginous layer separating the Permian black shale from Triassic Limestone. Studies that have presented geochemical data to support a theory of the end-Permian extinction lack any interpretation of post-depositional effects on Spiti Valley PTB sections. In order to accurately present a …


Spatiotemporal Analyses Of Child Pedestrian-Vehicle Incidents Occurring During School-Commuting Hours In Metro Atlanta From 2000 To 2007, Amy M. Moore May 2011

Spatiotemporal Analyses Of Child Pedestrian-Vehicle Incidents Occurring During School-Commuting Hours In Metro Atlanta From 2000 To 2007, Amy M. Moore

Geosciences Theses

From 2000 to 2007, the five core county area of Metropolitan Atlanta (Fulton, Dekalb, Clayton, Cobb and Gwinnett) experienced 1,871 incidents involving child pedestrians. Nearly one-third of these incidents occurred during school-commuting hours. This study examines the geospatial locations of these incidents, with regards to the location of all 647 public schools within the study area. A GIS is used to analyze the spatiotemporal arrangement of these incidents in order to find risk factors and patterns in the data. Aspects of the built environment are then considered in areas with higher frequencies of child pedestrian-vehicle incidents. A walkability assessment is …


Mineralogy And Geochemistry Of The Bauxite Deposits (Cretaceous), Wilkinson County, Georgia., Adebayo O. Ayorinde May 2011

Mineralogy And Geochemistry Of The Bauxite Deposits (Cretaceous), Wilkinson County, Georgia., Adebayo O. Ayorinde

Geosciences Theses

Cretaceous bauxite deposits from Hall and Veneer mines, Wilkinson County, Georgia are composed of kaolinite, gibbsite, goethite, anatase, nordstrandite and bohemite. Quartz and micas are absent in the samples. The presence of boehmite and goethite are evidence of intense weathering forming the bauxite deposits. The extremely high values of the Chemical Index of Alteration (CIA) which is over 99, and the low values of the alkali metals and alkali earth metals, support an intense weathering origin for the bauxite deposit. There is evidence of deposition in the mines based on the presence of pisoids in the bauxite samples and the …


Particle Size, Critical Shear Stress, And Benthic Invertebrate Distribution And Abundance In A Gravel-Bed River Of The Southern Appalachians, Helen Mayoral May 2011

Particle Size, Critical Shear Stress, And Benthic Invertebrate Distribution And Abundance In A Gravel-Bed River Of The Southern Appalachians, Helen Mayoral

Geosciences Theses

To determine the relationship between the abundance and density of benthic invertebrates, and the critical shear stress of individual grain sizes, a reach along Smith Creek, was divided into ten 2m x 2m quadrants. Within each quadrant, five randomly selected clasts for each grain size ranging from 2.26 to 25.6 cm were cleaned for benthic invertebrates. Wolman pebble counts for each quadrant were also conducted and used to determine the critical Shields stress per grain size fraction from the model given by Wiberg and Smith (1987) that explicitly accounts for particle hiding/sheltering effects in mixed-bed rivers. Particle entrainment values were …


Intensive Study Of Ambient Carbon Dioxide Variability In Urban Atlanta, Brian L. Vann Mr. May 2011

Intensive Study Of Ambient Carbon Dioxide Variability In Urban Atlanta, Brian L. Vann Mr.

Geosciences Theses

Urban areas contain multiple sources and sinks of carbon dioxide, yet spatial and temporal information explaining its variability, diurnal patterns, and effects from human activity are limited. The city of Atlanta, due to conflicting air masses, geographic location, and population growth, is as an excellent location to study carbon dioxide concentrations across its urban landscape. Mobile measurements of ambient CO2 concentrations were obtained at 1.5m above ground level along a transect in winter 2010 within the perimeter of Atlanta. Analyses of winter 2010 CO2 variability at GSU’s stationary CO2 monitor was also explored. The results showed that …


A Prospective Analysis On The Sustainability Of The Great Smoky Mountains National Park, Austin Bailey Porter May 2011

A Prospective Analysis On The Sustainability Of The Great Smoky Mountains National Park, Austin Bailey Porter

Chancellor’s Honors Program Projects

No abstract provided.


Remote Sensing Of Sediments And Volatiles On The Martian Surface And Terrestrial Analog Sites, Craig James Hardgrove May 2011

Remote Sensing Of Sediments And Volatiles On The Martian Surface And Terrestrial Analog Sites, Craig James Hardgrove

Doctoral Dissertations

The role of water and volatiles in the solar system is of critical interest in planetary science. Evidence for the past action of water or direct observation of water on a planetary body can indicate the potential to harbor life and is critical to human exploration of the solar system. We study two very different remote sensing techniques that address the issue of identifying water-related processes on the surface of other planetary bodies, and in particular, Mars. The first technique, combined thermal infrared and visible imaging, has been used extensively on Mars for determining the thermal inertia of surface materials. …


Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, Zachary Smith May 2011

Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, Zachary Smith

Natural Resources Management and Environmental Sciences

No abstract provided.


Vertebrate Taxonomic Composition, Species Diversity, And Paleoecology Of Two Pliocene Mid-Latitude, Inland-Basin Fossil Assemblages: Panaca Local Fauna (Lincoln County, Nevada) And Hagerman Local Fauna (Twin Falls County, Idaho), Vicki Lynn Meyers May 2011

Vertebrate Taxonomic Composition, Species Diversity, And Paleoecology Of Two Pliocene Mid-Latitude, Inland-Basin Fossil Assemblages: Panaca Local Fauna (Lincoln County, Nevada) And Hagerman Local Fauna (Twin Falls County, Idaho), Vicki Lynn Meyers

UNLV Theses, Dissertations, Professional Papers, and Capstones

I studied the sedimentology, species diversity, relative abundance, paleoenvironment, and paleoecology of the vertebrate fauna of the early Pliocene (Blancan Land Mammal Age) Panaca Formation of southeastern Nevada, and I compared these data with the slightly younger Hagerman fauna of south-central Idaho. The purpose of this study is to characterize the paleoecology and species diversity of mid-latitude inland basins during the Blancan Land Mammal Age, a time of climate change and immigrating taxa from Asia and South America. This study involved surface collecting and screenwashing of the Panaca Formation sediment in Meadow Valley, as well as a compilation of data …


Carbon And Sulfur Cycling In Early Paleozoic Oceans, Cara Kim Thompson May 2011

Carbon And Sulfur Cycling In Early Paleozoic Oceans, Cara Kim Thompson

Doctoral Dissertations

Here, I evaluate biospheric evolution during the Ordovician using high-resolution inorganic carbon and sulfur (carbonate-associated sulfate and pyrite) isotope profiles for Early Ordovician to early Late Ordovician strata from geographically distant sections in Western Newfoundland and the Argentine Precordillera. Additionally, I present new, high-resolution U-Pb ages for volcanic ash beds within strata of the Argentine Precordillera. Carbon isotope data record subdued variation that is typical of Early- to Middle Ordovician strata worldwide. By contrast, sulfur-isotopic compositions of carbonate-associated sulfate reveal a complex signal of short-term, rhythmic variation superimposed over a longer-term signal. This short-term, rhythmic variation occurs in all sections …


Constraining Martian Sedimentation Via Analysis Of Stratal Packaging, Intracrater Layered Deposits, Arabia Terra, Mars, Sarah Beth Cadieux May 2011

Constraining Martian Sedimentation Via Analysis Of Stratal Packaging, Intracrater Layered Deposits, Arabia Terra, Mars, Sarah Beth Cadieux

Masters Theses

Craters within Arabia Terra, Mars, contain hundreds of meters of layered strata

showing systematic alternation between slope- and cliff-forming units, suggesting either

rhythmic deposition of distinct lithologies or lithologies that experienced differential

cementation. Hypothesized origins of these intercrater layered deposits include

lacustrine, aeolian, volcanic airfall, and impact surge deposition. On Earth, rhythmically

deposited strata can be examined in terms of stratal packaging, wherein the interplay of

tectonics, sediment deposition, and change in base level results in predictable patterns

with respect to changes in the amount of space available for sediment accumulation.

Fundamental differences between tectonic regimes of Earth and Mars …


Sedimentologic And Stratigraphic Analysis Of Units Defining The Basal Sauk Supersequence Across The Craton Margin Hinge Zone, Southeastern California, Eric Gordon Hogan May 2011

Sedimentologic And Stratigraphic Analysis Of Units Defining The Basal Sauk Supersequence Across The Craton Margin Hinge Zone, Southeastern California, Eric Gordon Hogan

Masters Theses

In the Death Valley and Mojave Desert regions of southeastern California, the contact separating the lower and middle members of the Wood Canyon Formation (WCF) is currently interpreted as a regional scale unconformity coincident with the base of the Sauk Sequence. Regional mapping of this surface, however, reveals a nonconformable contact with underlying crystalline basement in cratonic settings, and a relatively conformable contact atop a northwest thickening wedge of miogeoclinal strata that is capped by the lower member of the WCF. Consistent with an unconformity, the progressive loss of three carbonate units within the lower member of the WCF has …


Evapotranspiration In The Riparian Zone Of The Lower Boise River With Implications For Groundwater Flow, Brady Allen Johnson May 2011

Evapotranspiration In The Riparian Zone Of The Lower Boise River With Implications For Groundwater Flow, Brady Allen Johnson

Boise State University Theses and Dissertations

Riparian zones in semi-arid regions often exhibit high rates of evapotranspiration (ET) in spite of low soil moisture content due to vegetation that is able to withdraw water from shallow aquifers. This work better defines the relationship between ET and the saturated zone by comparing the observed water table drawdown to analytically modeled drawdown in fully penetrating wells of an unconfined aquifer in response to daily ET flux. ET at the Boise Hydrogeophysical Research Site or BHRS (a riparian zone in a temperate, semi arid environment) is calculated following the approach of Batra et al. (2006) but uses site …


From Hillslopes To Canyons, Studies Of Erosion At Differing Time And Spatial Scales Within The Colorado River Drainage, Christopher Tressler May 2011

From Hillslopes To Canyons, Studies Of Erosion At Differing Time And Spatial Scales Within The Colorado River Drainage, Christopher Tressler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis includes two different studies in an attempt to investigate and better understand the key characteristics of landscape evolution. In the first study, the rate of surface particle creep was investigated through the use of Terrestrial lidar at an archaeological site in Grand Canyon National Park. The second study developed ways to quantify metrics of the Colorado River drainage and reports the role of bedrock strength in the irregular profile of the trunk Colorado River drainage.

Archaeological sites along the Colorado River corridor in Grand Canyon National Park are eroding due to a variety of surficial processes. The nature …


Geoenabling A Rural Community Through Web Gis: A Case Study Of The City Of Hays, Ellis County Kansas, Eamonn W. Coveney May 2011

Geoenabling A Rural Community Through Web Gis: A Case Study Of The City Of Hays, Ellis County Kansas, Eamonn W. Coveney

Master's Theses

The objective of this study was to describe the internet GIS implementation in the City of Hays and Ellis County, Kansas, then compare it to examples of implementation from other similar communities. Geospatial resources were consolidated from both agencies and used to develop two web mapping applications for employee and public access. Both mapping applications were developed on the ArcGIS Server platform using the .NET Web Application Developer Framework. In addition, a HTML website was developed to accommodate common data requests and an online map repository. The implementation approach of the City of Hays and Ellis County is similar to …


Spatial Analysis Of A Bioterrorist Attack On Four Major United States Cities Using An Aerosolized Hemorrhagic Fever Virus, Kathryn Prinslow May 2011

Spatial Analysis Of A Bioterrorist Attack On Four Major United States Cities Using An Aerosolized Hemorrhagic Fever Virus, Kathryn Prinslow

Master's Theses

Before the attack on September 11,2001, the United States was very vulnerable to a biological attack. Since then, those responsible for the security of the United States Homeland Security have become more aware of the country's vulnerability. Biological agents have the potential to give small groups of people unprecedented power to terrorize, as indicate by the "Amerithrax" attack in 2001, and of all of these agents, none have more potential for destruction than Ebola Hemorrhagic Fever (EHF). This research uses one of the deadliest viruses that have not been eradicated to identify the number of fatalities in an outbreak affecting …


The Mammals And Paleoindian Artifact From The Feaster Sand Pit, Late Pleistocene (Wisconsin)-Early Holocene, Of Cowley County (Southeastern), Kansas, Miranda L. Lucas May 2011

The Mammals And Paleoindian Artifact From The Feaster Sand Pit, Late Pleistocene (Wisconsin)-Early Holocene, Of Cowley County (Southeastern), Kansas, Miranda L. Lucas

Master's Theses

Over 100 fossil remains of late Pleistocene (Wisconsin)-early Holocene mammals, including one modified by paleoindians into an arrow shaft straightener were recovered from the Feaster sand pit in the southwestern part of Cowley County, Kansas. Taxa identified to species include Procyon lotor (Linnaeus), Mammut americanum (Kerr), Mammuthus columbi (Falconer), Mammuthus jeffersonii (Osborn), Equus scotti (Gidley), Equus conversidens (Owen), Camelops hesternus (Leidy), Antilocapra americana (Ord), and Bison antiquus (Ledy). The Feaster sand pit is thought to be late Pleistocene (Wisconsin) to early Holocene in age due to the high co-occurrence of mammals that are similar to the taxa of known late …


An Allosaurus From The Morrison Formation (Late Jurassic) Of Converse County, Wyoming, Dennis D. Roth May 2011

An Allosaurus From The Morrison Formation (Late Jurassic) Of Converse County, Wyoming, Dennis D. Roth

Master's Theses

I describe a partial skeleton of a theropod from the Later Jurassic Morrison Formation of Converse County, Wyoming. Collected material included 17 vertebrae, three ribs, two associated left metatarsals and an incomplete ilium of an Allosaurus in a gray silty-mudstone containing conchostraca. Several vertebrae are deformed with transverse processes broken and pressed against the neural spine, or twisted transverse processes from lateral or dorso-venteral compression. The material has evidence of erosion prior to deposition, as well as during postfossilization. I propose the deformation of the vertebrae is due to a demineralization of the bones. The flattened surfaces appear to have …


Pleistocene Climate In Alaska From Stable Isotopes In An Ice Wedge, Corinne Y. Griffing May 2011

Pleistocene Climate In Alaska From Stable Isotopes In An Ice Wedge, Corinne Y. Griffing

UNLV Theses, Dissertations, Professional Papers, and Capstones

The CRREL permafrost tunnel offers a unique opportunity to sample ice wedges in a climate-controlled environment, penetrating frozen silts which host massive ground ice that may record Dansgaard-Oeschger (D-O) and Heinrich Events. Ice wedges in the tunnel have been dated to approximately 36-22 ka (Hamilton et al., 1988), allowing the paleoclimate of the region to be reconstructed during MIS 3, when D-O and Heinrich events were documented in various other records. These climate cycles are rapid climate oscillations that have been recognized in records from the Arctic and subarctic, and suggest that climate can rapidly shift by 10°C over millennial …


Lateral Variability Of Facies And Cycles In The Furongian (Late Cambrian) Carbonate Platform: An Example From The Big Horse Member Of The Orr Formation In Western Utah, U.S.A., Ratna Widiarti May 2011

Lateral Variability Of Facies And Cycles In The Furongian (Late Cambrian) Carbonate Platform: An Example From The Big Horse Member Of The Orr Formation In Western Utah, U.S.A., Ratna Widiarti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Carbonate depositional cycles and sequences have been proposed to be formed by glacioeustatic sea-level changes. This mechanism would be questionable during times of high atmospheric CO2 and negligible continental ice sheets such as the supergreenhouse time in the Furongian (late Cambrian), during which limited glacioeustatic sea-level changes would be expected. A detailed sedimentological study of the Furongian Orr Formation in western Utah is aimed at testing the hypothesis that, under supergreenhouse climate conditions, most meter-scale carbonate cycles may have been formed through autocyclic processes and thus they should be laterally variable. The research was conducted in a small area ( …