Master of Science, University of Akron, 2024, Geology

Partial melting of hydrous phases such as amphibole, biotite, and muscovite occurs in orogens where distributed ductile thinning is causing exhumation of mid- to lower-crustal rocks. The partial melting of these hydrous phases contributes significantly to the physical and chemical evolution of the crust, as well as affecting the crust's strength. The Si-rich melts generated from partial melting reactions of mid- to lower-crustal assemblages migrate toward the upper crust leaving a more mafic restite. Previous laboratory experiments conducted on amphibole-, biotite-, or muscovite-bearing rocks performed at rapid strain rates (10-4/s to 10-5/s) result in brittle deformation due to high local pore pressures. These rapid experiments suggest this brittle behavior is the likely mechanism causing melt segregation in the crust. However, field evidence and slower strain rate experiments (10-6/s to 10-7/s) suggest that crystal plastic processes may be dominant during syndeformational partial melting. To investigate grain-scale melt segregation mechanisms in a common lower crustal protolith, I performed a suite of axial compression and general shear experiments on an amphibole-bearing source rock during syndeformational partial melting at T = 800-975°C, Pc = 1.5 GPa, at a strain rate (ε) of 1.6 x 10-6/s. I also performed axial compression experiments on a biotite-bearing gneiss and a muscovite-bearing quartzite at T = 950°C, Pc = 1.5 GPa, at a strain rate (ε) of 1.6 x 10-6/s to compare the differences in melt development depending on which hydrous phase is partially melting. The Nemo Amphibolite (d = 140 ± 85 μm) is composed of 62 vol% amphibole (Fe-hornblende), 27 vol% plagioclase (andesine; An30Ab69Or1), 8 vol% quartz, and 3 vol% titanite. The biotite-bearing gneiss (d = 80 +/- 40 microns) consists of quartz (43 vol%), plagioclase (andesine (An22Ab77Or1); 40 vol%), biotite (16 vol%), and ~1 vol% muscovite/Fe-Ti oxides. The muscovite-bearing quartzite is composed of 90 vol% q (open full item for complete abstract)

Committee: Caleb Holyoke (Advisor); Molly Witter-Shelleman (Committee Member); David Steer (Committee Member) Subjects: Earth; Experiments; Geochemistry; Geological; Geology; Mineralogy; Petrology; Plate Tectonics

PhD, University of Cincinnati, 2021, Engineering and Applied Science: Computer Science and Engineering

Scientist developers are developing systematic testing techniques to assure software quality, routinely. A key challenge is the oracle problem, a situation in which appropriate mechanisms are unavailable for checking if the code produces the expected output when executed using a set of test cases (TCs). Metamorphic testing (MT) alleviates the oracle problem by specifying the relationship that a source TC and its follow-up TC shall meet. Such relationships are called metamorphic relations (MRs) which are necessary properties of the intended program's functionality. Through checking whether the MRs hold or not, MT, a property-based software testing technique, can be applied to overcome the oracle problem. Scientific model developers are able to verify and validate their software via MT, even when the expected output of a given TC is not readily available. The tenet is to check whether certain relations hold among the expected outputs of multiple related inputs. Based on MT and MRs, the overall objective of this dissertation is to achieve a function as a service (FaaS) architecture by developing and deploying a new class of services called metamorphic software services. These services, expressing different relations between software outputs, will serve a broad range of stakeholders in a similar way that MRs serve software testers. To that end, the first component of this research is to develop useful metamorphic software services which are based on the research of the MRs. After obtaining useful metamorphic software services for the community of Storm Water Management Model (SWMM, a dynamic rainfall-runoff simulation model that computes runoff quantity and quality from primarily urban areas), the second component is to engage social media information in metamorphic software service discovery. Finally, the third component aims to build and deploy the metamorphic software services in a FaaS way, so as to provide a serverless platform for SWMM communities. This dis (open full item for complete abstract)

Committee: Nan Niu Ph.D. (Committee Chair); Raj Bhatnagar Ph.D. (Committee Member); Chia Han Ph.D. (Committee Member); Carla Purdy Ph.D. (Committee Member); Michelle Simon Ph.D. (Committee Member) Subjects: Computer Science

PhD, University of Cincinnati, 2023, Engineering and Applied Science: Computer Science and Engineering

Given a test input, not knowing the expected output of the software under test (SUT) is called the oracle problem. An emerging method of alleviating the oracle problem is metamorphic testing (MT). Rather than focusing on the correctness of output from a single execution of the SUT, MT exploits metamorphic relations (MRs) as derived oracles for checking the functional correctness of the code. Although researchers have argued that MT can be a simple and effective technique to help software developers, little is known about the actual cost of constructing MRs in real-world software and the relationship between MT and the already well-adopted method in software development. This research examines a series of practices to evaluate the effectiveness of MT during software development. Our investigation is conducted within the context of a real-world scientific software, the Storm Water Management Model (SWMM), developed and maintained by the U.S. Environmental Protection Agency (EPA). To ensure SWMM's accuracy in modeling stormwater runoff and executing hydraulic and water quality simulations, the development team continually evolves the software. Among the challenges they face, software testing stands out as one of the most technically complex tasks. Our research initially investigates the current testing practices and software quality assurance (QA) workflows in scientific software development, taking the SWMM as a case study. The value of our work resides in the qualitative characterizations and quantitative assessments of the tests that scientific software developers have independently written and released within the SWMM context. Our findings indicate that oracles indeed play a role in scientific software testing. Furthermore, by employing an empirical approach, we identified four critical requirements for the improved integration of MT into scientific software development. Constructing MRs is critical because without them, MT cannot b (open full item for complete abstract)

Committee: Nan Niu Ph.D. (Committee Chair); Wen-Ben Jone Ph.D. (Committee Member); Tingting Yu Ph.D. (Committee Member); Boyang Wang Ph.D. (Committee Member); Michelle Simon Ph.D. (Committee Member) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2023, Materials Science and Engineering

The work in this dissertation is focused on the development of new manufacturing technologies at the early stage. Two concepts are developed in the category of Impact Welding and two in the category of Metamorphic Manufacturing. Under the Impact Welding category two different welding processes are studied, the Vaporizing Foil Actuator Welding and the Augmented Laser Impact Welding processes. Both of these processes were demonstrated to produce impact welds between traditionally unweldable aircraft aluminum alloys which performed as well or better than comparable riveted joints without the need for the drilling of holes or removal of surface coatings. Additionally, basic engineering guidelines are established for the design of foils for the Vaporizing Foil Actuator Welding process and basic performance metrics are established for the Augmented Laser Impact Welding technique. Two new data analysis techniques were developed for the Augmented Laser Impact Welding process which were validated by the use of high-speed videography. Models of the impact conditions for both of these impact welding techniques were established. For the Augmented Laser Impact Welding process, a technique for accurately measuring the welding velocity during an impact event is developed and validated. Metamorphic Manufacturing refers to the agile use of deformation to create shapes and modify microstructure. In this area two concepts were developed where metallic components are transformed from one shape into a second more desirable and useful form. A device and process for bending medical fixation plates to match patient skeletal anatomy is developed. The method can make arbitrary controlled shapes and may save time in the operating room for reconstruction surgeries. The second concept is an approach for Robotic Blacksmithing, a process for incrementally transforming a malleable material into useful shapes by deformation. This concept was initially developed on a purpose-built desktop robotic (open full item for complete abstract)

Committee: Glenn Daehn (Advisor); Antonio Ramirez (Committee Member); Boyd Panton (Committee Member); Enam Chowdhury (Committee Member) Subjects: Materials Science; Medicine; Robotics

Master of Science, University of Akron, 2023, Geology

Within the mid to lower continental crust distributed ductile thinning occurs, in orogens that form mountains like the Himalayas and Appalachia, due to a weak middle to lower crust that deforms laterally in response to loading of a thickened, cold upper crust. This thinning destabilizes large orogens and causes the exhumation of hot and weak rock from the mid to lower crust that begins to partially melt. This melting further weakens the rocks and may affect the deformation mechanisms operating in the crust. Melting has been seen to have impacts on the deformation mechanisms and resulting lattice preferred orientations (LPO) that form in olivine-basalt aggregates (Holtzman et al., 2003). To investigate the effects of partial melting on deformation mechanisms and LPO development in two common foliated felsic rocks, I performed general shear deformation experiments on a fine-grained quartzite and fine-grained gneiss at T = 800°C, 850°C, 900°C, 950°C, or 975°C, P = 1.5 GPa, and strain rate of 6*10-5/s. The quartzite (grain size ~30 microns) is composed of 90% quartz and 10% muscovite. The fine-grained gneiss (grain size ~50 microns) is composed of 43% quartz, 40% plagioclase, 16% biotite, and 1% accessory minerals. The foliation in the slices of each rock was oriented parallel to the shear plane between Al2O3 shear pistons with a cut made at 45° to the compression direction. Experiments were performed at a range of temperatures to change the melt fraction present in the rocks during deformation (Melt = ~0%, 0.25%, 0.5%, and 1%). The yield stress of Moine Thrust quartzite decreased as a function of increasing temperature from ~1000 to ~300 MPa. However, all the experiments with melt present (T equal to to greater than 850°C) significantly strain hardened after a shear strain (g) of 1. This hardening may be due to the presence of melt along grain boundaries which is absorbing water from the recrystallizing quartz grains which slows diffusive recovery in quartz. The Gne (open full item for complete abstract)

Committee: Caleb Holyoke (Advisor); John Peck (Committee Member); Molly Witter-Shelleman (Committee Member) Subjects: Earth; Environmental Geology; Experiments; Geochemistry; Geological; Geology; Geophysics; Geotechnology; High Temperature Physics; Mineralogy; Petrology

MS, University of Cincinnati, 2021, Engineering and Applied Science: Computer Science

Large collections of data help evolve deep learning into the state-of-the-art in solving many artificial intelligence problems. However, the requirements engineering (RE) community has yet to adapt to such sweeping changes caused exclusively by data. One reason is that the traditional requirements quality like unambiguity becomes less applicable to data, and so do requirement fault detection techniques like inspections. In this work, we view deep learning as a class of machines whose effects must be evaluated with direct consideration of inherent data quality attributes: accuracy, consistency, currentness, etc. We do this by taking a case study of MSDGC and combined sewer overflow (CSO) problem. CSO represents significant risks to human health as untreated water is discharged to the environment. Municipalities recently began collecting large amounts of water-related data and considering the adoption of deep learning solutions like recurrent neural network (RNN) for overflow prediction. We substantiate our view by altering stationarity of the multivariate time-series data, and by further analyzing how the stationarity changes affect the behavior of an RNN in the context of predicting CSO. Our work sheds light on the active role RE plays in deep learning. We also contribute a novel metamorphic relation (MR) to characterize RNN robustness in the presence of missing data. We show how this relation drives automated testing of three implementation variants: LSTM, GRU, and IndRNN thereby uncovering deficiencies and suggesting more robust solutions for overflow prediction.

Committee: Nan Niu Ph.D. (Committee Chair); Raj Bhatnagar Ph.D. (Committee Member); Anca Ralescu Ph.D. (Committee Member) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2020, Materials Science and Engineering

III-V/Si multijunction photovoltaics possess the potential for high power conversion efficiencies (surpassing the single-junction limit) at low cost by leveraging the inexpensive and scalable Si platform. Both space and terrestrial markets can benefit from this technology; however, multiple materials-related obstacles must first be overcome in order to truly demonstrate this potential and enable adoption of this new technology. For terrestrial usage, low-cost III-V deposition techniques are necessary to remain cost competitive with current photovoltaics. Given a Si bottom cell, the optimal series-connected dual-junction photovoltaic efficiency for both space and terrestrial solar spectra is achieved with a 1.7-1.8 eV top cell, which is most conveniently provided by GaAsyP1-y (y ~0.7-0.8) at around 3% lattice mismatch to the Si substrate. While epitaxial integration of GaAsyP1-y alloys on Si is favorable over high-cost and non-scalable wafer bonding or stacking techniques, controlling (minimizing) dislocation content within the strain-relaxed metamorphic materials, and/or minimizing its impact on top cell performance via careful device design, is key to achieving optimal performance. Materials challenges related to the heterovalent, lattice-mismatched GaP/Si interface and the thermal expansion coefficient mismatch of GaAsyP1-y to Si all complicate the production of low-defect density GaAsyP1-y materials. To this end, we have undertaken metalorganic chemical vapor deposition (MOCVD) growth studies of GaP/Si nucleation layers and GaAsyP1-y step-graded buffers, demonstrating substantial progress by reducing defect densities by over an order of magnitude in the course of this recent work. These efforts have largely been enabled via rapid feedback regarding crystalline defect populations obtained from electron channeling contrast imaging (ECCI). From these experimental studies, a deeper understanding of dislocation dynamics in these metamorphic materials is reac (open full item for complete abstract)

Committee: Tyler Grassman (Advisor); Suliman Dregia (Committee Member); Michael Mills (Committee Member); Roberto Myers (Committee Member) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 2018, Electrical and Computer Engineering

III-V multijunction solar cells (MJSC) are capable of the highest conversion efficiencies among all solar cell classifications. These devices are thus of major interest for both terrestrial and space applications. However, the economics of the terrestrial and space markets leads to significantly different design requirements for III-V MJSCs to become more economically viable in each market. In the terrestrial market, despite their high efficiency, the high manufacturing cost of III-V MJSCs currently limits their applicability in a market that is currently dominated by crystalline silicon. Thus, lower cost III-V MJSC approaches must be developed for them to become more competitive. This intuitively leads to the concept of merging III-V MJSCs with Si solar cells to demonstrate III-V/Si MJSCs. Such an approach simultaneously takes advantage of the high conversion efficiency of III-V MJSCs and the low-cost manufacturing of Si. In the space market, III-V MJSCs are already the dominant technology due to their high efficiency, radiation hardness, and reliability in extreme conditions. However, new III-V MJSC approaches must be developed if they are to push the boundary of conversion efficiency even further. An approach to improve the efficiency and thus economic viability is through the use of additional high-performance sub-cells at optimal bandgaps to more ideally partition the solar spectrum. Although the design requirements for improving the economic viability of III-V MJSCs in the terrestrial and space markets differ drastically, the design of III-V MJSCs can be altered to meet the design requirements for both markets by using the versatile technique of III-V metamorphic epitaxy. This is the growth of relaxed (i.e. unstrained) III-V compounds at a lattice constant that differs from that of the substrate. The major advantage of III-V metamorphic epitaxy is that it provides an additional degree of freedom for III-V MJSC device design. Traditional lattice-matche (open full item for complete abstract)

Committee: Steven Ringel (Advisor); Tyler Grassman (Committee Member); Sanjay Krishna (Committee Member); Lei Cao (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2014, Electrical and Computer Engineering

Utilizing major advances in III-V/Si epitaxy is a promising approach to realize high-efficiency, cost efficient terrestrial solar power. The successful demonstration of planar GaP epitaxial layers free of nucleation-related defects grown on Si by both MBE and MOCVD establishes extremely fertile ground for the development of high quality III V devices on Si substrates. Solar cell devices in particular stand to benefit, and not only by the merging of the best performing photovoltaic materials with the cost, availability, and scalability advantages of Si substrates, but also because of the advanced state of Si PV itself. With this motivation in mind, several aspects of a III-V/Si multijunction solar cell are investigated in this dissertation. Such a device requires many advanced and novel components. The use of GaP as the bridge from Si to the wide range of III-V materials renews interest in a material whose activity in research efforts had faded significantly since the advent of modern growth techniques and GaAs-based heterostructures in the 1980s. GaP-based research is also motivated by the fact that it represents the far lesser studied binary component of both GaxIn1-xP and GaAsyP1-y, two alloys essential to the wider scope of high efficiency PV research. Efforts to advance the ability to grow GaP by MBE and MOCVD were undertaken. Post-growth surface morphologies of homoepitaxial GaP films grown by MBE and MOCVD have been studied. Smooth, stepped surface morphologies of MBE-grown layers, measured by atomic force microscopy, were found for a wide range of substrate temperatures and P2:Ga flux ratios. A MOCVD-based growth study performed under similar conditions to MBE-grown samples show a nearly identical smooth, step-flow surface morphology, presenting a convergence of growth conditions for the two different methods. Electrical characterization of these films was then carried out by Hall effect measurements and DLTS to determine transport properties and to test (open full item for complete abstract)

Committee: Steven Ringel Dr. (Advisor) Subjects: Electrical Engineering

BA, Oberlin College, 2014, Geology

Eclogites can be found in two distinct tectonic settings in the western USA: in the Franciscan Complex as tectonic blocks in a fossil accretionary wedge, and in the Navajo Volcanic Field as xenoliths in diatremes. Intra-crystal oxygen isotope analyses of garnets from these two settings provide important information on the source, composition and timing of fluid interactions in both eclogite settings. Because of the well-documented relationship between Franciscan subduction and the volcanism in the Navajo Volcanic Field, the samples in this study can be directly compared to determine if they share a common origin. The Navajo eclogites in this study have the first intra-garnet oxygen isotope zoning found in any mantle xenoliths. Xenolith garnets record core δ18O values of 7.8 to 10.3‰ consistent with altered upper oceanic crust. Rim values are lower in δ18O with values of 5.8 to 6.9‰, consistent with late garnet growth in equilibrium with slab-contaminated mantle fluids. Three garnets homogenous in δ18O were found. Atoll textures present in one sample record altered upper oceanic crust values in the atoll, with replacement cores and rims consistent with a mantle-dominated fluid. The presence of garnets homogenous in δ18O within a few mm of garnets zoned in δ18O suggests textural control, both intra- and inter-garnet, on oxygen zoning. In particular, a relationship between the extent of healed fracturing and oxygen zoning is observed across all the Navajo eclogite samples. Garnets homogenous in δ18O still record cation zoning, which is inconsistent with homogenization by diffusion. The presence of zoning in both cations and oxygen in these samples suggests a short residence time in the mantle, and a Mesozoic-Cenozoic origin. Franciscan eclogite garnets record altered upper oceanic crust core δ18O values of 9.3 to 13.3‰. Rim values in these samples range from 6.7 to 9.5‰. Low-δ18O rims record interaction with mantle or serpentinization fluids. High-δ18O rims suggest p (open full item for complete abstract)

Committee: F. Zeb Page (Advisor); Steve Wojtal (Committee Member); Karla Parsons-Hubbard (Committee Member) Subjects: Geochemistry; Geological; Geology; Petrology

Doctor of Philosophy, The Ohio State University, 2012, Electrical and Computer Engineering

Lattice-mismatched epitaxy in the III-V compound semiconductor system based on III-AsP and related alloys are of enormous importance, and considerable research interest, for many years. The reason is straightforward if one considers the limitations placed on available materials properties for devices dictated by lattice matching to the dominant substrate technologies - Si, GaAs (and/or Ge) and InP. For III-V epitaxy, the lattice constants of these substrates have defined a generation or more of device advances since growth of heterostructures possessing the same equilibrium lattice constants as the substrate yields essentially defect-free (specifically extended defect-free) materials and devices. Removing the restriction of lattice matching to current substrate technology opens a rich spectrum of bandgaps, bandgap combinations, conduction and valence band offsets, etc., that are desirable and exploitable for advancing device technologies for new functionality and greater performance. However successful exploitation of these properties requires mitigation of a variety of extended defects that result from the lattice mismatch between substrate and epitaxial heterostructures. A well known method to achieve this solution is through the use of compositionally (lattice constant-graded) buffer interlayers, in which the equilibrium lattice constants of interlayers are slowly altered by controlled changes in layer composition so that the mismatch strain between the initial substrate and the final device layers is spread across a thickness of buffer. The research accomplished has yielded success for both lattice constant ranges Si – GaAs and GaAs - InP. For the Si – GaAs system, a three step GaP nucleation process on Si has been developed and demonstrated, which maintains total avoidance of creating coalescence-related defects such as antiphase domains and stacking faults resulting from the initial III-V/IV interfaces while reducing overall threading dislocation density by ~1 (open full item for complete abstract)

Committee: Steven Ringel PhD (Advisor); Siddharth Rajan PhD (Committee Member); Roberto Myers PhD (Committee Member) Subjects: Accounting; Electrical Engineering; Engineering; Materials Science

Doctor of Philosophy, The Ohio State University, 2009, Electrical and Computer Engineering

The use of step-graded SiGe buffers to accommodate the lattice constant difference between Si and III-V materials is an extremely promising approach to achieve monolithically integrated III-V optoelectronic device technology on Si wafers. The potential of this technology has already been demonstrated by the integration of numerous high performance GaAs-InGaP based devices on Si substrates. As a result, there is now a great interest in knowing the basic properties of residual defects within the III-V/SiGe materials and devices since their understanding is fundamental to maintain the progress achieved to date. The focus of this research if to investigate “grown in” defects present within GaAs and InGaP-based layers and devices grown on SiGe/Si generating a fundamental understanding on defect introduction in lattice mismatch III-V/SiGe heteroepitaxy. The role of the SiGe substrate is analyzed by comparing deep level properties with identical structures grown on GaAs substrates. Results showed that the presence of dislocations do not introduced additional deep levels. In addition, and from the point of view of the technology, the effect of radiation damage in III-V/SiGe PV structures is analyzed, specifically detection and identification of “ambient-generated” defects that result from the application of these materials and photovoltaic devices operating in the space environment. In this dissertation the first radiation study for III-V/SiGe structures was performed. Results indicated that for single junction GaAs structures, the primary impact of the SiGe/Si substrate was to improve the radiation-tolerance of these devices, in particular for n+p GaAs diodes. While DLTS results showed generally lower radiation-induced trap concentrations for both n-type and p-type GaAs grown on SiGe compared to growth on conventional substrates, the reduction was far more dramatic for p-type GaAs. The improved radiation-tolerance for GaAs grown on SiGe/Si is attributed to interactions bet (open full item for complete abstract)

Committee: Steven Ringel A (Advisor); Wu Lu (Other); George Valco J (Other); Dennis Guenther A (Other) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 2007, Electrical Engineering

Anion-based InAsP metamorphic step-graded buffers are a novel solution to the lattice-mismatch problem of devices with the lattice constant between InP and InAs grown on InP substrates. Compared to mixed-cation step-graded buffers, recent work shows InAsP step-graded buffers have achieved smoother surface morphology and lower threading dislocation density. The focus of this dissertation will be to investigate the fundamental growth science of InAsP metamorphic step-graded buffers using solid source molecular beam epitaxy. The structural and electronic properties of InAsP step-graded buffers will be explored by various characterization approaches, including high resolution X-ray diffraction, electron microscopy, Hall measurements, etc. and compared to those of mixed-cation step-graded buffers. Based on the characterization results, the buffer design of InAsP step-graded buffers will be optimized, aiming to achieve high-quality material for device applications. This research is expected to provide a further understanding of the growth, material properties and device application of InAsP metamorphic step-graded buffers.

Committee: Steven Ringel (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2005, Electrical Engineering

Integration of III-V materials on Si substrates has been a driving force in the area of lattice-mismatched growth to selectively provide the complementary material properties of compound semiconductors within conventional Si technology. This materials integration potentially serves as a novel host for next generation technologies to maintain the current rate of progress in data speed and capacity. There are barriers present to integrate III-V materials to Si such as mismatches in lattice constant (for example, 4 % between GaAs and Si, 8 % for InP), crystal symmetry (polar vs. non-polar), thermal characteristics (typically over 250 % thermal expansion coefficient difference between III-V materials and Si), and chemistry. Extensive efforts have focused on achieving successful integration of III-As materials (mainly GaAs/AlGaAs) on Si via heteroepitaxy, while advances in materials integration led state-of-the-art device performance by leveraging heteroepitaxial versatility to tailor material properties among compound III-V materials. Recent progress on graded SiGe relaxed buffers produced successful results with low threading dislocation density of ~ 1 × 10 6 cm -2 achieved for the relaxed Ge over large area Si wafers, consequently leading to outstanding device-quality GaAs materials grown on Si and high-performance optoelectronic devices. However, optoelectronic devices emitting in the visible portion of the spectrum have yet to be explored using this promising approach. The present work explores the untapped opportunities of integrated III-P materials on Si enabled by relaxed SiGe/Si, therefore verifying the concept of SiGe/Si that is broadly applicable for monolithically integrating optical and electronic technologies at the wafer level. One of the ultimate proofs for examining the quality of the materials being integrated is a demonstration of the stimulated emission. The generation of coherent light originates from interaction between photons and population-invert (open full item for complete abstract)

Committee: Steven Ringel (Advisor) Subjects:

Master of Science (MS), Ohio University, 2009, Geological Sciences (Arts and Sciences)

The western Cycladic island of Serifos (Aegean region, Greece) is an exhumed Aegean metamorphic core complex (MCC) exposing greenschist- to lower amphibolite-facies metamorphic rocks cross-cut by two separate magmatic intrusions: an older, S-type mylonitic orthogneiss that syn-kinematically intruded into a mid-crustal shear zone; and a younger, undeformed I-type granodiorite that intruded post-kinematically into shallow crust. Thermochronometric constraints presented here elucidate the timing of cooling and exhumation of the MCC through mid-crustal levels. 40Ar/39Ar thermochronology performed on white micas reveal two distinct cooling age populations: (1) metamorphic rocks of the Cycladic Blueschist Unit (CBU) yielded 35-28 Ma cooling ages; and (2) rocks from within the mylonitic orthogneiss yielded 9-8 Ma cooling ages. These results represent two episodes of exhumation and cooling, commencing in the Early Oligocene with extrusion of the CBU-equivalent rocks and culminating in the Late Miocene with development of an MCC, and indicate rapid multistage exhumation of the western Cyclades.

Committee: Gregory Nadon PhD (Advisor); Douglas Green PhD (Committee Member); Keith Milam PhD (Committee Member) Subjects: Geology

Doctor of Philosophy, Miami University, 2012, Geology and Environmental Earth Science

Supradetachment basins are asymmetric extensional depocenters that develop in the hanging walls of low-angle detachment faults in metamorphic core complexes, and display a sedimentary and structural record of the uplift, exhumation and extensional deformation history of both the footwall and hanging wall units. Exhumed, high-grade lower to middle crustal rocks and syn-extensional granitoid intrusions in the core complexes commonly make up the main provenance of these basins. Thus, a better understanding of the structure, stratigraphy and tectonic history of supradetachment basins in higly-extending terrains provides significant information and spatial-temporal constraints about the mode, nature and kinematics of extensional deformation. This dissertation study has focused on the structure and tectonics of the Alasehir detachment fault and supradetachment basin in the Central Menderes Massif in western Anatolia (Turkey) in order to quantify the uplift, exhumation and cooling history of the Menderes core complex in the late Cenozoic, and the associated accommodation space development in response to extensional deformation. In this Ph.D study I have documented the supradetachment basin evolution in continental extension; fault kinematics in supradetachment basin development; structure, petrofabric and geochemistry of a syn-extensional granitoid intrusion in the Menderes core complex; and, diachronous exhumation and cooling history of the Menderes core complex based on the results of the low-temperature thermochronology analysis. The results and implications of this work also answer some other important questions regarding the mode and nature of continental extensional deformation in the Aegean province of western Anatolia, fault-controlled segmentation and compartmentalization of supradetachment basins, and the role of magmatism in extensional deformation and metamorphic core complex formation in general.

Committee: Yildirim Dilek PhD (Advisor); Mike R. Brudzinski PhD (Committee Member); Brian S. Currie PhD (Committee Member); Jason Rech PhD (Committee Member); Samir Bali PhD (Committee Member) Subjects: Geochemistry; Geological; Geology; Sedimentary Geology

MS, Kent State University, 2010, College of Arts and Sciences / Department of Earth Sciences

In the Western Tatra Mountains, the Variscan-age (~340 Ma) exhumed shear zone, reveals high-grade metamorphic rocks thrust over medium-grade metamorphic rocks, creating an unusual macroscopic rock geometry known as an inverted metamorphic sequence. Polyphase petrographic fabrics record the formation of the inverted metamorphic sequence, making it ideal for characterizing mid-crustal deformation mechanisms of large-scale tectonic processes. A combination of microstructural (optical petrography) and microanalytical (monazite EMPA, Titanium thermometry, Electron backscatter diffraction-EBSD fabric analysis) techniques reveal the dynamic processes involved in the evolution of this major crustal-scale discontinuity. The timing of the Early Variscan continent-continent collision was measured by U/Pb monazite dating at c. 370 Ma in the mica schists, with titanium-in-zircon temperatures of ~ 880 °C in the migmatite. These data reflect the peak metamorphic conditions of Early Variscan deformation. During or following exhumation of the high-grade rocks into the mid-crust, titanium-in-quartz data suggests the newly formed inverted metamorphics coexisted at temperatures of approximately 540 °C. The age of Variscan SE thrusting (~ 340 Ma) and its kinematic indicators are lacking in the mica schists. Instead, additional monazite ages from mica schists correlate to younger (c. 315 Ma) plutonism/uplift? and microstructural and analytical results reflect kinematics in a E-W orientation. Collectively, data on the textures, temperatures, and timing within the Tatra tectonic zone do not support the ‘hot iron' model of inverted metamorphic formation. Rather, simultaneous or closely related exhumation of the high-grade metamorphics with orogen parallel extension.

Committee: Daniel Holm (Advisor); David Scneider (Committee Member); Donald Palmer (Committee Member) Subjects: Geological; Geology

Master of Science (MS), Bowling Green State University, 2012, Geology

The Blue Ridge province of the Appalachians is an allochthonous structural unit, which has been deformed into an anticlinorium that is overturned to the northwest. Folding and development of a pervasive southeast-dipping cleavage are attributed to the northwest transport of both crystalline and sedimentary thrust sheets during the late Paleozoic Alleghanian orogeny. Phyllites and schists in the late Proterozoic Catoctin Formation and in the Cambrian Harpers Formation have abundant evidence for multiple phases of deformation, though the timing and importance of these structures is still unclear. Fluid inclusion microthermometry along with detailed structural analyses of Late Proterozoic and Early Cambrian rocks in the Blue Ridge were completed to construct a fluid history of the region. The combination of these methods allows for characterization of deformation phases and estimation of pressure/temperature conditions, which provide a more comprehensive picture of the tectonic evolution of the region. Structural analysis established the geometry and timing of three deformation phases in relation to the pervasive Alleghanian cleavage. Microthermometry identified at least four fluids from primary, pseudosecondary, and secondary inclusions in quartz veins. Two-phase aqueous inclusions were used to characterize fluid populations on the basis of homogenization temperature and composition. Pre-cleavage veins are characterized by high temperature (Th ¿¿¿¿¿¿¿ 210 °C) fluids with moderate salinities (approximately 5-15 wt. NaCl equivalent). Syn-cleavage fluids occur at moderate temperatures (Th = 150-205 °C) and variable salinities (approximately 5-25 wt. NaCl equivalent). Post-cleavage fluids are characterized by low temperatures (Th ¿¿¿¿¿¿¿ 150 °C) and low salinities (approximately 2-10 wt. NaCl equivalent). Eutectic temperatures indicate both simple and complex mixtures of Na, Ca, and Mg brines in successive vein generations. Migrating, orogenic fluids found in the adjace (open full item for complete abstract)

Committee: Charles Onasch (Advisor); John Farver (Committee Member); Kurt Panter (Committee Member) Subjects: Geology

Master of Science, University of Akron, 2010, Geology

X-Ray Fluorescence (XRF), petrography, and Energy-Dispersive X-ray Spectrometry (EDAX) have been used to determine the element concentration in samples and their distribution within minerals for 222 metamorphic rock samples from the Black Hills, S.D. Element concentrations in these samples are compared to sample location and known gold deposits in the Black Hills. XRF data of rock chips from whole rock samples were collected using a portable XRF unit to determine major, minor and trace element abundances. Statistical analyses of the XRF data indicates a moderate to strong correlation between gold and the elements Mn (19 to 16,116 ppm), S (1,283 to 79,452 ppm), As (n.d. to 132 ppm), Pb (n.d. to 318 ppm), Cl (625 to 31,277 ppm), Ba (n.d. to 1,101 ppm), and Zn (n.d. to 266 ppm) thus indicating these elements may serve as proxy indicators of gold. The integration of elemental data with ArcGIS was used to test the spatial relationship of proxy elements to known gold deposits in the Precambrian core of the Black Hills. Sixteen samples having gold concentration greater than 18 ppm were chosen for more detailed analyses. EDAX raster scans of these samples determined proxy element variations within individual mineral grains. Petrographic analyses were done to identify minerals and their textural relationships. Sample proximity to known gold deposits in the Black Hills can be correlated with increases in minor and trace proxy element concentrations.

Committee: LaVerne Friberg Dr. (Advisor); John Szabo Dr. (Committee Member); John Peck Dr. (Committee Member) Subjects: Geographic Information Science; Geological; Geology; Mineralogy; Mining; Petrology