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Provenance Signature Of A Forearc Basin Modified By Spreading Ridge Subduction: Detrital Zircon Geochronology And Detrital Modes From The Paleogene Arkose Ridge Formation, Southern Alaska, Cullen Kortyna

Honors Theses

Upper Paleocene–Eocene boulder conglomerate, cross-stratified sandstone, and laminated carbonaceous mudstone of the Arkose Ridge Formation exposed in the southern Talkeetna Mountains record fluvial-lacustrine deposition proximal to the volcanic arc in a forearc basin modified by Paleogene spreading ridge subduction beneath southern Alaska. U-Pb ages of detrital zircon grains and modal analyses were obtained from stratigraphic sections spanning the 2,000 m thick Arkose Ridge Formation in order to constrain the lithology, age, and location of sediment sources that provided detritus. Detrital modes from 24 conglomerate beds and 54 sandstone thin sections aredominated by plutonic and volcanic clasts and plagioclase feldspar with …

Crustal Structure Across The Central Alaska Range: Anatomy Of A Mesozoic Collisional Zone, P.R.K. Brennan, H. Gilbert, K. D. Ridgway

Department of Earth, Atmospheric, and Planetary Sciences Faculty Publications

A first-order process in the growth of continents is the collision and accretion of terranes against continental margins. Collision leads to the formation of a suture zone between the accreted terrane and the former continental margin. New insights on the suturing process are observed from two receiver function transects across the Mesozoic Alaska Range suture zone. Three distinct crustal sections are identified from observations of crustal thickness, intracrustal discontinuities, and Vp/Vs: a northern section with ∼27 km thick crust of felsic to intermediate composition, a central section that is ∼37 km thick that exhibits intracrustal discontinuities and has felsic to …

117-124 Chlorococcal Chlorophyte Composition, Community Structure, And Seasonal Variations In The Shallow Lakes Of The Kızılırmak Delta, Turkey, Faruk Maraşlioğlu, Eli̇f Neyran Soylu, Ari̇f Gönülol

Turkish Journal of Biology

The chlorococcal chlorophyte community structure and seasonal variations in terms of species composition and abundance of dominant species in Tatlı, Gıcı, Liman, and Cernek lakes (Samsun, Turkey) were investigated between 1996 and 2003. Species richness and diversity (Shannon-Weaver, H^') were measured monthly from stations at the surface of each lake. Changes in the Chlorococcales community structure were examined with nonmetric multidimensional scaling (NMDS) ordinations. A total of 36 Chlorococcales species were identified in these lakes located in the Kızılırmak Delta. While the Chlorococcales composition was similar in Tatlı, Gıcı, and Liman lakes, Cernek Lake showed different seasonal trends, indicating high …

Determining Anchoring Systems For Marine Renewable Energy Devices Moored In A Western Boundary Current, Michael G. Seibert

Electronic Theses and Dissertations 2010 - 2019

In this thesis anchoring systems for marine renewable energy devices are examined for an area of interest off the coast of Southeast Florida that contains both ocean current and thermal resources for future energy extraction. Bottom types observed during previous regional benthic surveys are compiled and anchor performance of each potential anchor type for the observed bottom types is compared. A baseline range of environmental conditions is created by combining local current measurements and offshore industry standards. Numerical simulations of single point moored marine hydrokinetic devices are created and used to extract anchor loading for two potential deployment locations, multiple …

Interpretation Of Well Test Data From Two Hydraulically Communicating Reservoirs, Bander Ibrahim Al Quaimi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Naturally fractured reservoirs (NFR) have been receiving more attention than ever since the beginning of the last decade due to various reasons. The current understanding is not sufficient to achieve a favorable recovery factor due to the complexity associated with the fracture characterization and the dynamic behavior of the fractured system. The majority of the fractured reservoirs are developed. Therefore, before proceeding into secondary or possibly tertiary recovery processes a thorough understanding must be reached to avoid undesirable results. The huge reserve volume present in fractured oil and gas reservoirs motivate engineers, researchers, and geoscientists to exert additional efforts to …

Apparent Weekly And Daily Earthquake Periodicities In The Western United States, And Evolution Of Wadi Kubbania In Egypt, Ali Hadi Atef

Doctoral Dissertations

"The dissertation consists of two separate sections. The first section is on apparent daily and weekly periodicities in earthquake occurrence in the western United State [sic]. Analysis of Apparent Seismicity Rate (ASR) in the western United States confirmed the existence of prominent spectral peaks with a period of 1 and 7 days. The number of recorded earthquakes on Sundays for the duration of 1963-2008 is about 5% higher than that on weekdays, and, more significantly, there is a 9% increase of ASR in the early morning compared with that in the middle of the days. Significant similarities between the spatial …

Designing And Using Virtual Field Environments To Enhance And Extend Field Experience In Professional Development Programs In Geology For K-12 Teachers, Frank Douglas Granshaw

Dissertations and Theses

Virtual reality (VR) is increasingly used to acquaint geoscience novices with some of the observation, data gathering, and problem solving done in actual field situations by geoscientists. VR environments in a variety of forms are used to prepare students for doing geologic fieldwork, as well as to provide proxies for such experience when venturing into the field is not possible. However, despite increased use of VR for these purposes, there is little research on how students learn using these environments, how using them impacts student field experience, or what constitutes effective design in light of emerging theories of geocognition.

To …

Deforestation, Drought And Humans: New Discoveries Of The Late Quaternary Paleoenvironment Of Rapa Nui (Easter Island), Candace Lynn Gossen

Dissertations and Theses

The mystery of the trees of Rapa Nui (Easter Island) is a complex problem within a dynamic ecosystem. With new physical cores from the volcanic crater lake Rano Kao, this dissertation uncovers a detailed 15,000 year ecological history of Easter Island and its climatic variability. New radiocarbon dating methods establish a more precise chronology which shows that the island before human habitation was very different than what we know today. It had a simple but prolific ecology that transitioned into a barren grassland. What factors caused the transition are unclear but are likely to be human related. As the forests …

On Constrained Optimization Schemes For Joint Inversion Of Geophysical Datasets, Uram Anibal Sosa Aguirre

Open Access Theses & Dissertations

In the area of geological sciences, there exist several experimental techniques used to advance in the understanding of the Earth. We implement a joint inversion least-squares (LSQ) algorithm to characterize one dimensional Earth's structure by using seismic shear wave velocities as a model parameter. We use two geophysical datasets sensitive to shear velocities, namely Receiver Function and Surface Wave dispersion velocity observations, with a choice of an optimization method: Truncated Singular Value Decomposition (TSVD) or Primal-Dual Interior-Point (PDIP). The TSVD and the PDIP methods solve a regularized unconstrained and a constrained minimization problem, respectively. Both techniques include bounds into the …