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Browsing by Author "Harry, Dennis, committee member"

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    Evaluating the impact of deep-water channel architecture on the probability of correct facies classification using 3D synthetic seismic data
    (Colorado State University. Libraries, 2021) Langenkamp, Teresa Rose, author; Stright, Lisa, advisor; Harry, Dennis, committee member; Eykholt, Richard, committee member
    Modeling studies of bed-to geobody-scale architecture in deep-water channel deposits reveal that channel element stacking patterns and internal architecture strongly control connectivity. This architecture is critical to understanding hydrocarbon flow and recovery but is unresolvable in exploration-scale seismic-reflection profiles. Forward seismic reflectivity modeling of a digital outcrop models is commonly used to explore how depositional architecture is interpretable in a filtered seismic response. One limitation of forward seismic reflectivity modeling studies is that they often stop short of qualitatively assessing the link between underlying depositional architecture and seismic response. This study addresses the gap between qualitative interpretation and quantitative evaluation by calculating the prediction reliability of inverted seismic data. Specifically, this study uses synthetic 3D seismic modeling and inversion of a 3D outcrop model of deepwater channels in the Tres Pasos Formation of the Magallanes Basin of southern Chile. The model includes outcrop- (bed and geobody) to seismic- (reservoir to basin) scale architecture. The primary objective is to quantify where and when channel architecture is accurately predicted by seismic facies classification. Bayesian classification is used to test the probability of correct facies classification from P-impedance and if the classification results are dependent upon architectural styles (e.g., channel element stacking patterns). Model sensitivity variables include seismic frequency (ranging from 15 to 180 Hz) and deep versus shallow rock properties. Results show that prediction reliability increased for both channel element axis sandstone and mass transport deposits with increasing frequency. Deep reservoirs or faster seismic velocities more accurately predict facies than shallow reservoirs or slower seismic velocities due to the increasing contrast between sandstone and shale velocities. Channel axis sandstone is less easily interpreted where channel elements are vertically aggraded, reducing acoustic impedance contrasts with background shale. When channel elements are laterally stacked or disorganized, facies can be predicted from seismic attributes with a higher confidence, due to a strong contrast between channel element sandstone and background shale. This study highlights that architectural information strongly impacts 3D inverted seismic data and highlights conditions that either hinder or aid accurate interpretation from facies classification.
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    Measuring seismic anisotropy in the mantle wedge of Japan's subduction system using shear wave splitting of SKS and SKKS waves
    (Colorado State University. Libraries, 2014) Pierce, Jamie, author; Schutt, Derek, advisor; Breidt, Jay, committee member; Egenhoff, Sven, committee member; Elkins, Joe, committee member; Harry, Dennis, committee member
    Mantle flow patterns can provide a better understanding of mantle deformation and composition in subduction systems. These flow patterns can be inferred by measuring seismic anisotropy. Previous anisotropy studies of Japan's subduction system have found complex fast axis polarizations. Here we seek to better constrain fast axis directions through shear wave splitting of SKS and SKKS waves from events with magnitudes greater than 6.5. Data were collected from the Japanese National Research Institute for Earth Science and Disaster Preventions (NIED) F-net array for stations located over all of Japan. Results from shear wave splitting measurements show trench-parallel fast axes trends near the Ryukyu and Japan Trenches and trench-perpendicular fast axes further away from these trenches. Fast axes near the Nankai Trough align with the subducted plate motion. The Kuril Trench fast axes are roughly perpendicular to subducted plate motion. A simple 2D corner flow model can explain the flow of the mantle wedge if B-type olivine deformation, indicative of hydrated asthenosphere under high stress, is the source of the fast axes perpendicular to mantle flow direction near the Ryukyu Trench, Japan Trench, and Kuril Trench.
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    Public archaeology and geophysics: searching for unmarked human burials in rural Colorado
    (Colorado State University. Libraries, 2023) Rowe, Donald J., author; Henry, Edward, advisor; Harry, Dennis, committee member; LaBelle, Jason, committee member
    Rural communities in Colorado are often left in control of lands that potentially contain unmarked burials. Two such communities in Colorado, Gould and Wray, are interested in examining the possible existence of unmarked burials on public lands. The land near the Gould Community Center was used to house prisoners of war during the final year of World War 2 and the community believes mostly fallen concrete markers (one still stands) found at the site may be related to burials from that time. Wray, CO in Yuma County is home of the East Yuma County Cemetery Board (EYCCB), which manages the Kingston and Evangelical Lutheran Cemeteries. The EYCCB took over management of these properties after periods of abandonment and the burial records are lost, this has the left them with potential unmarked burials at each of these sites. The expense and ethical concerns related to accidental disinterment provide rural communities an incentive to locate any unmarked burials on land they manage. I combined four geophysical methods with historical information provided by community partners to determine what areas at the respective sites were most likely to contain unmarked burials. The four methods I employed include: ground-penetrating radar (GPR), electrical resistivity tomography (ERT), electromagnetic induction (EMI), and magnetometry. Using these methods, I was able to locate numerous geophysical anomalies and geolocate them in the mapping software of ArcGIS Pro. In Gould I was unable to determine the source of the geophysical anomalies found due to the wide variety of uses the site has had in the past as well as the lack of historical evidence for burials. Historical evidence of previous burials at the Kingston and Evangelical Lutheran Cemeteries allowed me to make the argument that these anomalies were potentially related to burials. At Evangelical Lutheran Cemetery I concluded the cemetery is likely to contain unmarked burials throughout the southern half of the site. However, the lack of geophysical markers suggests that the soil in the northern quarter of the site is largely undisturbed and likely does not have burials. I concluded that Kingston Cemetery is expected to contain burials in the south and west of the site. Additionally, the part of Kingston Cemetery that is least likely to contain unmarked burials is the northeastern corner of the site, with a strip along the northern boundary that possibly contains burials.
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    Rhenium-osmium geochronology and geochemistry of the Upper Jurassic marine black shales, Agardhfjellet Formation, Central Spitsbergen, Svalbard and mercury degradation of Upper Permian shales, East Greenland and mid-Norwegian shelf
    (Colorado State University. Libraries, 2024) Park, Junhee, author; Hannah, Judith, advisor; Harry, Dennis, committee member; Borch, Thomas, committee member; Georgiev, Svetoslav, committee member; Hammer, Øyvind, committee member; Olaussen, Snorre, committee member
    Every rock has its own story. Rocks are categorized as igneous, metamorphic, and sedimentary types based on their origins and overprinting processes. The human species is confronting the crisis of climate change and some rocks hold a climate story from the past, permitting speculation on the future. On the geological time scale, Earth has experienced both scorching and freezing environments, the latter referred to as Snowball Earth. A critical key to resolving the problems we are facing lies in geology, which deconvolutes environments where specific rocks have formed. This dissertation addresses Boreal sedimentary sections during the Late Jurassic period by conducting three projects; Project I pinpoints depositional ages for black shales from the Agardhfjellet Formation and discusses Os isotopic ratios in the Boreal ocean during the Late Jurassic. Project II evaluates the depositional environments of the Agardhfjellet Formation, which was deposited during a shelf dysoxic-anoxic event. Project III focuses on Hg degradation incurred during incipient weathering and calls attention to interpreting Hg signals of sedimentary rocks, which have been used as an indicator of ancient volcanism. This dissertation provides new radiometric ages and detailed geochemical discussions of the Late Jurassic Agardhfjellet Formation and cautions the use of Hg concentrations when interpreting from outcrop sections. The findings herein significantly enhance our understanding of shelf dysoxic-anoxic events compared with oceanic anoxic events and Hg behavior during the early stage of weathering.
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    Sedimentology, facies architecture and sequence stratigraphy of a Mississippian age, black mudstone succession -- the upper member of the Bakken Formation, North Dakota, U.S.A.
    (Colorado State University. Libraries, 2013) Borcovsky, Damien A., author; Egenhoff, Sven, advisor; Harry, Dennis, committee member; von Fischer, Joseph, committee member; Fishman, Neil, committee member
    The early Mississippian age, upper member of the Bakken Formation in the North Dakota portion of the Williston Basin consists of a succession of organic-rich, black siliciclastic mudstones deposited offshore on a low-gradient ramp or shelf. Based on ichnological and sedimentological characteristics twelve fine-grained facies are recognized within the succession and these are grouped into five reoccurring facies associations. Very fine-grained, massive to faintly laminated mudstone (FA1) records deposition in the deepest, calmest parts of the offshore environment, whereas well laminated mudstones (FA2a), well laminated clay clast-bearing mudstones (FA2b), burrow-mottled mudstone with shells (FA3), and interlaminated siltstone and mudstone (FA4) contain sedimentological evidence that argues for deposition in the shallower, less calm, and generally more proximal parts of the offshore environment. These proximal-offshore mudstones (FA2a, FA2b, FA3, and FA4) reflect (1) variation in overall bottom water oxygen levels from dysoxic to possibly as high as oxic, and (2) lateral variation in the input of silt and clay clasts along the basin margin. Ubiquitous Phycosiphon incertum fecal strings throughout the succession along with patches of small shells and centimeter-scale burrows, and rare agglutinated foraminifera indicate that the upper Bakken member was likely deposited primarily in dysoxic to suboxic basinal conditions, and not within a persistently stratified, anoxic environment. In all facies associations, storm event laminae deposited by bedload processes range from sparse to ubiquitous. Repeated stacking of facies associations, which reflect different offshore energy regimes define up to ten coarsening-upward parasequences mostly 0.15-0.60 m thick. These are bounded by flooding surfaces that can be correlated laterally for at least 300 km through the basin, delimiting individual parasequences. Distinct formation-scale facies changes indicate that the lower half of the succession, herein termed Interval 1, represents the distal expression of a transgressive systems tract and was characterized by high radiolaria productivity with minor silt input during higher order sea level lowstands. The upper half of the succession, herein termed Interval 2 represents the distal expression of the base of a highstand systems tract. In contrast to Interval 1, the Interval 2 mudstones are generally characterized by high clay content, low radiolaria productivity, and intermittent colonization of the sea floor by bivalves and millimeter to centimeter-scale burrowing organisms during higher order sea level lowstands. Core descriptions, radiolaria distribution patterns, x-ray diffraction data and comparisons to other shale plays in the United States of America suggest that mature mudstones in the Interval 1 part of the succession outside of the depocenter, and in isolated silt-rich sub-basins, might be sufficiently brittle and permeable to exploit for hydrocarbons utilizing horizontal drilling and hydraulic fracturing technologies.
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    Tertiary lake sedimentation in the Elko Formation, Nevada -- the evolution of a small lake system in an extensional setting
    (Colorado State University. Libraries, 2015) Horner, William H., author; Egenhoff, Sven O., advisor; Harry, Dennis, committee member; von Fischer, Joe, committee member; Amerman, Robert, committee member
    The Lower to Middle Eocene Elko Formation of northeastern Nevada consists of basal coarse-grained siliciclastics and carbonates which are overlain by an organic-rich succession consisting of fine-grained siliciclastics, in places with fine-grained carbonates, and fine- to coarse-grained volcaniclastics at the top. Based on lithological and sedimentological characteristics in four documented localities arranged along a north-south transect, the succession shows fourteen facies, which are grouped into five facies associations (FAs): Siliciclastic mudstones and conglomerates (FA1); Massive coal-rich mudstones (FA2); Microbial-mat-bearing mudstones and carbonates (FA3); Microbial-mat-bearing mudstones and volcaniclastics (FA4); Carbonates and volcaniclastics (FA5). The succession is interpreted to reflect deposition in a broad continental-lacustrine setting. FA1 rocks record sedimentation in the most proximal environment, consisting of alluvial-fluvial sedimentation. FA2 rocks reflect deposition in a marginal low-energy swamp environment, while FA3 rocks denote "open-water" lacustrine sedimentation in a limnetic setting that was highly sensitive to lake-level fluctuations. FA4 rocks record the onset of extrabasinal airfall tuff in the limnetic portion of the lake, and FA5 rocks record volcaniclastic sedimentation outpacing subsidence in the lake, ultimately "filling" up available accommodation space and ending lacustrine sedimentation. The studied succession is subdivided into four vaguely chronostratigraphic intervals referred to as Stratigraphic Intervals 1 to 4, which record a lake system with significant lateral changes in accommodation space and resulting facies patterns in a north to south progression through time. Based on two recent 40Ar/39Ar dates and four previous radiometric age dates, the northern outcrop, which is significantly older than the central and southern ones, records initial subsidence and the onset of lake sedimentation (Stratigraphic Interval 1). Subsidence varied over time causing the lacustrine depocenter and limnetic depozone to progressively shift southwards (Stratigraphic Intervals 2 through 4). Black shale source rocks in the measured sections therefore occur along the entire north-south transect of the studied lacustrine system, yet they represent rocks of different ages not correlatable throughout the Elko Formation. Coeval volcanism, which led to increased volcaniclastic sediment supply, followed black shale deposition and contributed to the north-south "filling in" of the lake system, ultimately culminating with the end of lacustrine sedimentation around 37.5 Ma. The Elko Formation black shales have high source rock potential as an unconventional resource play, as their organic content consists almost entirely of Type-I (oil prone) kerogen. Contrary to deep-water, thermally-stratified anoxic-lake source rock models, long considered to be the only environments in which significant organic-matter preservation may have occurred, this study provides evidence for black shale deposition in the Elko lake to have occurred within a "shallow," mostly oxic environment in the photic zone. Further, this research indicates that depositional environments in lacustrine settings may be scale-dependent. The Elko Formation is not merely a scaled-down version of large-lake systems, such as that in which the Green River Formation formed, but a unique type of system with its own set of controls. With increased industry attention being placed on this potential lacustrine petroleum system, this study provides a new source rock model, as well as a temporal and spatial framework to be used as a predictive tool for the identification of rich source rock intervals in the Elko Basin.
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    Using waveform modeling of seismic anisotropy to understand the process of Proterozoic lithospheric assembly
    (Colorado State University. Libraries, 2013) Solomon, Melinda A., author; Schutt, Derek L., advisor; Harry, Dennis, committee member; Hannah, Judy, committee member; Breidt, Jay, committee member
    In this study, SKS data from two long-standing broadband seismic stations located along the Proterozoic Trans Hudson Orogen is analyzed for the effects of complex anisotropy. The Trans Hudson Orogen is the lasting expression of collisional events that brought together Archean continental fragments to form the cratonic core of the North American continent. Split SKS waveforms observed at two GSN stations, FFC located on the Sask craton near Flin Flon, Manitoba, and RSSD located on the eastern margin of the Wyoming craton in the Black Hills of South Dakota, are analyzed for anisotropic layering of varying complexity. At FFC we find that a model with two flat layers of anisotropy is better able to explain the data than the simple model of one flat layer. A top layer shows anisotropy perpendicular to the convergence direction of the Trans Hudson Orogen that is similar to observations of anisotropy today at convergent margins, and is attributed to lithospheric deformation during convergence. RSSD shows more complex splitting that we interpret as sub-wavelength scale anisotropic heterogeneity resulting from convergence driven fragmentation of the pre-existing lithosphere into small, < ~40 km pieces. Previous studies show more coherent anisotropy to the east and west of RSSD, suggesting that anisotropic heterogeneity here is related to the convergence, and may be a longstanding feature of tectonic boundaries.