Department: Geology ![[clear]](close-x.png "Remove this limiter")
54 matches in the database.
These are records: 1 - 30.
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1.
Albrecht, Tony L.
A Triassic syndepositional detachment system, Ischigualasto Provincial Park, northwestern Argentina.
Degree: MS, Geology, 2005, Miami University
► The Ischigualasto basin of northwest Argentina contains ~4 km of non-marine strata.…
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▼ The Ischigualasto basin of northwest Argentina contains ~4 km of non-marine strata. In the southeast part of the basin, the Middle Triassic Los Rastros Formation contains a ~1 km 2 area where rocks exhibit both extensional and contractional deformation features. To the east, both high angle and listric normal faults are the dominant structures. To the west, deformation consists of reverse and thrust faults, in addition to upright and overturned folds. Faults in both areas sole into a sub-horizontal detachment surface, below which rocks are undeformed. Deformed Los Rastros Formation strata are overlain by lightly-deformed/undeformed rocks of the Upper Triassic Ischigualasto Formation. The Agua de la Peña detachment system is interpreted to have formed as a result of gravity spreading/depositional loading of lacustrine delta platform and fluvial deposits above an overpressured shale décollement. Although 2-3 orders of magnitude smaller, the cross-sectional shape and interpreted driving mechanisms of the Agua de la Peña detachment are similar to paired extensional-contractional fault systems formed along continental margins. Based on reconstructed geometry and interpreted rheology, the contractional portion of the detachment can be modeled as a critical-tapered wedge, and provides a small-scale analogue for fold-thrust belts formed in passive-margin settings.
Advisors/Committee Members: Currie, Brian S.
Subjects: Geology
Keywords: structural geology; extension; contraction; critical tapered wedge
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2.
Alten, John Michael.
Structural Analysis and brittle Deformation – Groundwater Relationships of the Rough Creek Fault Zone (RCFZ), Western Kentucky, USA.
Degree: MS, Geology, 2005, Miami University
► The Rough Creek Fault Zone is an east-west trending system of braided…
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▼ The Rough Creek Fault Zone is an east-west trending system of braided faults which penetrate Precambrian basement rocks in western Kentucky, and is one of many deformed zones within the Illinois Basin. The RCFZ was extensionally faulted in the late Precambrian during continental rifting. Compressional fault reactivation during the Paleozoic produced reverse and oblique-slip offset in the the overlying strata along pre-existing facults, and was followed by post-Paleozoic extension. Our report reveals evidence of fault reactivation, suggests models that may have produced structural relationships observed in outcrop, and establishes mechanical and temporal relationships of faults and fractures in the RCFZ. As a first approximation to the issue of groundwater-structure relationships, we compared structural data with published hydrogeologic information, the results of which suggest that subsurface permeability is unpredictable within the main RCFZ, and that permeability decreases with distance from the main fault zone as a function of decreasing fracture density.
Advisors/Committee Members: Dilek, Yildirim.
Subjects: Geology
Keywords: Rough Creek Fault Zone; Illinois Basin; groundwater; structural analysis; fractures
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3.
Bishop, Michael Edward.
MICROBIAL REDUCTION OF FE(III) IN MULTIPLE CLAY MINERALS BY SHEWANELLA PUTREFACIENS AND REACTIVITY OF BIOREDUCED CLAY MINERALS TOWARD TC(VII) IMMOBILIZATION.
Degree: MS, Geology, 2010, Miami University
► The reactivity of clay minerals toward technetium immobilization utilizing a suite of…
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▼ The reactivity of clay minerals toward technetium immobilization utilizing a suite of clay minerals ranging from smectite-illite including montmorillonite, nontronite, rectorite, mixed layered I-S (70:30), and illite, with chlorite (ripidolite), and palygorskite common in nature. The clay minerals were characterized utilizing multiple techniques. Fe-Oxides were removed prior to bioreduction using a modified dithionite-citrate-bicarbonate method. Fe (II) in the bioreduced clay minerals is used to reduce Tc(VII) to Tc (IV) in PIPES buffer. In the S:I series, the smectite end member was most effective in reducing Tc (VII) and the illite member the least effective, parallel to the extent and rate of Fe(III) bioreduction of these minerals. For all the clay minerals, the ratio of oxidized Fe(II) to reduced Tc(VII) was ~3.5±0.5. These kinetic results are important for our understanding of how various clay minerals may be used to immobilize heavy metal Tc at DOE contaminated sites.
Advisors/Committee Members: Dong, Hailiang.
Subjects: Environmental Geology; Geology; Microbiology; Mineralogy
Keywords: Smectite, montmorillonite, nontronite, mixed layered I-S, rectorite, illite, palygorskite, chlorite (ripidolite), Shewanella Putrifaciens CN-32, Fe(III) bioreduction, Fe(II) oxidation, Tc(VII) reduction, surface area, XRD, mössbauer, SEM, TEM
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4.
Bondre, Ninad R.
FIELD AND GEOCHEMICAL INVESTIGATION OF BASALTIC MAGMATISM IN THE WESTERN UNITED STATES AND WESTERN INDIA.
Degree: PhD, Geology, 2006, Miami University
► This dissertation consists of three sub-projects, each of which integrates field and…
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▼ This dissertation consists of three sub-projects, each of which integrates field and geochemical information to address specific questions pertaining to magmatism in three different continental basaltic provinces. It is expected that these sub-projects will contribute to a deeper understanding of various facets of basaltic magmatism. The first sub-project involves the Sangamner mafic dike swarm in the western Deccan Volcanic Province (DVP). This study, which is the first study of its kind from this province, uses a combination of field and geochemical characteristics to understand the relationship of the dikes with associated lava flows, and their position in the established Deccan stratigraphy. The results indicate that several dikes are geochemically similar to younger formations, and that NE-SW trending dikes in the central part of the area possibly represent a fissure system that could have fed lava flows of the Poladpur and / or Khandala formation. The second sub-project is the first attempt at integrating morphological, textural and compositional data to understand the emplacement of basaltic lava flows from the Steens Basalt in southeastern Oregon, and its eruptive history. The study reveals substantial morphological diversity within the Steens package. Typical compound pahoehoe flows are abundant – these were probably sourced from small to moderate-sized shield volcanoes, and grew as a network of overlapping, inflated lobes. Interbedded a’a and transitional flows suggest that physical parameters varied throughout the eruptive episodes. Geochemical data, in conjunction with morphological data hints at complex eruptive episodes that probably reflect complex processes at depth. These deserve to be investigated in greater detail. The final sub-project focuses on the newly-recognized Jordan Valley Volcanic Field (JVVF) in southeastern Oregon. An integration of field, geochemical and geochronologic information has been used to understand the evolution of this field through space and time, and to better understand the origin of other monogenetic volcano-fields. Salient results include the recognition of two major pulses of volcanism, long-lived vent alignments, and considerable chemical and isotopic diversity. This information is evaluated in terms of its implications for understanding issues pertaining to small-scale mantle heterogeneity, differentiation processes, and melt transport.
Advisors/Committee Members: Hart, William K.
Subjects: Geology
Keywords: basalt; lava flow; dikes; compositional diversity; emplacement
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5.
Borkiewicz, Olaf J.
Formation of Precursor Calcium Phosphate Phases During Crystal Growth of Apatite and Their Role on the Sequestration of Heavy Metals and Radionuclides.
Degree: PhD, Geology, 2010, Miami University
► Due to increasing risk associated with the contamination of the environment with…
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▼ Due to increasing risk associated with the contamination of the environment with heavy metals and radionuclides, societies worldwide are facing a pressing need for new more efficient environmental remediation techniques. One approach that gained considerable attention over the last two decades is in situ metal stabilization by phosphate amendments – a technique based on the coprecipitation of contaminant species with phosphates and the formation of insoluble metal(M)-substituted minerals, such as apatite Ca5-xMx(PO4)6(OH,Cl,F). One of the major results of this dissertation is that formation of apatite at Earth-surface conditions is preceded by crystallization of other less stable calcium phosphates (precursors) that ultimately transform to apatite. The first part of this dissertation investigates formation and evolution of calcium phosphate precursors under conditions simulating those found in Earth-surface environments. The pathways of phase development in the Ca(OH)2-H3PO4-H2O system were studied using conventional ex situ as well as in situ time-resolved X-ray diffraction. The results clearly indicate formation of precursors under conditions found at the Earth-surface, which may be relevant not only in the context of natural soil environments, but also in the context of engineered conditions, like those found during metal stabilization by phosphate amendments. In the second part of the dissertation, pathways of calcium phosphate development in the presence of different metal ions (Zn, Cd, Sr, U, and Th) are studied by time-resolved X-ray diffraction. The results clearly indicate a significant influence of contaminant species on the pathways of phase development in the Ca(OH)2-H3PO4-H2O system. Secondary metal-bearing phases, far more soluble than hydroxylapatite, were often formed in the presence of the metals studied. Finally, the role of precursor formation on the heavy metal sequestration and fate during crystal growth of apatite was studied by a combination of powder X-ray diffraction, SEM/EDS and ICP-AES. The results indicate significant reduction in the solution concentration of metals during formation of precursor phases and relative stability of the contaminant species during structural transformation of phases involved in low-temperature crystallization of hydroxylapatite. Fluctuations in the concentration of elements observed during structural changes in the system suggest a dissolution-recrystallization mechanism of transformation of amorphous phases to brushite and parascholzite.
Advisors/Committee Members: Rakovan, John.
Subjects: Mineralogy
Keywords: calcium phosphates; precursor phases; hydroxylapatite; time-resolved in situ X-ray diffraction; synchrotron
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6.
Bosze, Stephanie Lynn.
SURFACE STRUCTURALLY CONTROLLED SECTORAL ZONING IN FLUORITE: IMPLICATIONS TO UNDERSTANDING HETEROGENEOUS REACTIVITY AT THE MINERAL-WATER INTERFACE.
Degree: MS, Geology, 2001, Miami University
► This thesis consists of two separate but related manuscripts; Surface Structure Controlled…
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▼ This thesis consists of two separate but related manuscripts; Surface Structure Controlled Sectoral Zoning of REE in Fluorite from Long Lake, N.Y. and Bingham, N.M. and Mineralogy and paragenetic history of fluorites from Bingham, N.M. Links between REE chemistry, color and morphology. In the first paper, fluorite crystals from two deposits were identified as sectorally zoned with respect to the rare earth elements. It has been shown that the differential incorporation of the REE occurred during crystal growth due to heterogeneities in the atomic structure of the fluorite surface. The second paper addresses the use of the REE as petrogenetic indicators in actual hydrothermal deposits. This study attempts to identify if there is a systematic correlation between REE chemistry and other factors, such as crystal morphology, and color, or if compositional variability merely reflects temporal variation in hydrothermal fluids.
Advisors/Committee Members: Rakovan, John F.
Keywords: REE; fluorite; sectoral zoning; Hansonburg Mining District; hydrothermal; distribution coefficients; color; morphology; Bingham NM; Long Lake NY; paragenesis; petrogenetic indicators; surface structure; differential partitioning; trace elements
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7.
Boyarko, Devin C.
SPATIAL AND TEMPORAL PATTERNS OF NON-VOLCANIC TREMOR ALONG THE SOUTHERN CASCADIA SUBDUCTION ZONE.
Degree: MS, Geology, 2009, Miami University
► Episodic tremor and slip (ETS), the spatial and temporal correlation of slow…
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▼ Episodic tremor and slip (ETS), the spatial and temporal correlation of slow slip events (SSE) monitored via GPS surface displacements and non-volcanic tremor (NVT) monitored via seismic signals, is a newly discovered mode of deformation thought to be occurring down-dip from the seismogenic zone along several subduction zone megathrusts. We investigate in detail eight NVT episodes between 2005 and 2007 with source locations extending over a 650 km along-strike region from northern California to northern Oregon. The initiation and termination points of laterally-continuous tremor activity appear to be repeatable features between NVT episodes which support the hypothesis of segmentation within the ETS zone. We find as much as 50 km spatial offset from the up-dip edge of the tremor source zone to the down-dip edge of the thermally- and geodetically-defined transition zones. NVT activity is also spatially anticorrelated with local seismicity, suggesting the two processes occur exclusive of one another.
Advisors/Committee Members: Brudzinski, Michael.
Subjects: Geophysics
Keywords: non-volcanic tremor; slow slip; segmentation; Cascadia; subduction zone; transition zone
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8.
Brueseke, Matthew Edward.
Mid-Miocene Magmatic System Development in the Northwestern United States.
Degree: PhD, Geology, 2006, Miami University
► This dissertation investigates the spatial, temporal, geochemical, and petrologic development and evolution…
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▼ This dissertation investigates the spatial, temporal, geochemical, and petrologic development and evolution of mid-Miocene volcanic systems in the southeastern Oregon Plateau region of Oregon and Nevada. This integrated field and laboratory investigation conclusively demonstrates that flood basalt volcanism occurred on the Oregon Plateau over at least a 2 m.y. duration, and provides the first comprehensive view into the development of a mid-Miocene Oregon Plateau volcanic field and its relationship with regional flood basalt volcanism. The first portion of this study focuses on the geochemical and chronostratigraphic characteristics of flood basalt lava flows in the vicinity of Steens Mountain, Oregon. New 40Ar/39Ar ages and recalculated literature ages from the Steens Basalt type section illustrate that multiple magmatic centers were present locally, and that Oregon Plateau flood basalt activity was coeval with the main phase of Columbia River Basalt Group volcanism. The remainder of this study focuses on the Santa Rosa-Calico volcanic field (SC) of northern Nevada in order to better define and understand the link between mid-Miocene Oregon Plateau mafic and silicic volcanism. In the SC, mafic through silicic eruptive loci and shallow intrusive bodies are exposed along broadly north-south trending alignments, coincident with regional lithospheric structures. At least sixteen physically and compositionally distinct units are exposed in the SC representing approximately 2 m.y. of magma production. Local mafic volcanism was dominated by the eruption of Steens Basalt magmas. SC silicic magmas were produced by basaltic magma induced crustal melting of granitoid upper crust and erupted from diverse vent types and locations. At least four distinct intermediate (andesite-dacite) magmatic systems also are documented. Physical, chemical, and isotopic data indicate that open-system petrogenetic processes played a substantial role in the generation of these magmas and also influenced the chemical characteristics of SC mafic and silicic units. The complex array of physical and chemical characteristics and processes displayed and documented by SC units provide an exceptional example of how compositionally diverse volcanic fields develop. Moreover, these complexities establish an important link between regional mid-Miocene mafic magma production and the generation of silicic-dominated volcanic fields on the Oregon Plateau.
Advisors/Committee Members: Hart, William K.
Subjects: Geochemistry; Geology
Keywords: Steens Mountain; Oregon Plateau; Miocene; flood basalts; 40Ar/39Ar; Yellowstone; Steens Basalt; Owyhee-Humboldt; Santa Rosa-Calico; silicic volcanism; andesite; dacite; basalt; rhyolite; Nevada; Oregon; McDermitt; continental volcanism; pyroclastic
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9.
Cosky, Brian Wright.
Os-Sr-Nd-Pb ISOTOPIC AND TRACE ELEMENT STUDY OF MAGMATIC PROCESSES WITHIN THE SIERRA DEL CHICHINAUTZIN VOLCANIC FIELD, TRANS-MEXICAN VOLCANIC BELT.
Degree: MS, Geology, 2010, Miami University
► The petrogenetic processes that lead to compositional diversity in mafic volcanism of…
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▼ The petrogenetic processes that lead to compositional diversity in mafic volcanism of the Sierra Chichinautzin Volcanic Field (SCVF), central Mexico, are not well understood. This study involves an investigation of the trace element and Sr-Nd-Pb-Os isotope systematics, to constrain the relative roles of crustal assimilation versus subduction processes in generating enriched geochemical signatures in the mafic magmas of the SCVF. Both lower and upper crustal assimilation are ruled out, respectively, by the positive correlation of 187Os/188Os and 206Pb/204Pb, and the negative correlations between Pb/Ce and 187Os/188Os and 206Pb/204Pb. Rather, the data suggest that the compositional diversity of the SCVF magmas results from melting of a heterogeneous mantle wedge that has been metasomatized to variable degrees by hydrous fluids from the subducting altered oceanic crust and sediment, as well as a sediment melt component.
Advisors/Committee Members: Widom, Elisabeth.
Subjects: Geochemistry
Keywords: osmium, subduction, isotope, Mexico; Sierra Chichinautzin
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10.
Crimmins, Laura G.
Structure and Chemistry of Minerals in the Ca-(As,P)-(OH,F,Cl) Apatite System: Johnbaumite, Svabite, and Turneaureite from Franklin and Sterling Hill, New Jersey, USA.
Degree: MS, Geology, 2012, Miami University
► The Franklin and Sterling Hill deposit is unusual in its wide variety…
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▼ The Franklin and Sterling Hill deposit is unusual in its wide variety of apatite group minerals. Those in the Ca-(As,P)-(OH,F,Cl) system are of interest to mineralogists for several reasons including their potential use in environmental remediation. The chemistries of 29 samples from this deposit were determined using electron microprobe analysis (EMP), and the structures of 17 of these were determined using single crystal X-ray diffraction (XRD). The samples range in percentage of arsenic occupying the tetrahedral site of the apatite structure from 0.052% to 99.116%. As the amount of arsenic increases, most atomic bond distances within the structures expand, but the Ca1-O1 bond length decreases as a result of steric constraints placed on the oxygen atoms surrounding the Ca1 site by the bonded arrangement of tetrahedron to them. Raman spectra revealed continuous changes in peak positions and intensities associated with vibrational modes of the tetrahedral site along this solid solution.
Advisors/Committee Members: Rakovan, Dr. John.
Subjects: Chemistry; Environmental Geology; Geochemistry; Geology; Mineralogy
Keywords: structure; chemistry; Raman; fluorapatite; hydroxylapatite; johnbaumite; svabite; turneaureite
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11.
Croley, Allison L.
THE ARAGONITE TO CALCITE TRANSFORMATION: A LABORATORY STUDY.
Degree: MS, Geology, 2002, Miami University
► The goal of this laboratory study was not only to examine portions…
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▼ The goal of this laboratory study was not only to examine portions of the aragonite to calcite transformation, but to do so with conditions that were similar to a modern carbonate environment. Specifically, it was concerned with diagenetic changes that occur in an aquifer when unstable carbonate sediments are exposed to meteoric water. Flow through the freshwater phreatic zone of an aquifer was simulated in Plexiglas columns by circulating water through a column of modern, aragonite ooids. Based on geochemical analyses, only portions of the aragonite to calcite transformation were observed. Dissolution of the aragonite ooids occurred at both a PCO2 of 10-3.5 and a PCO2 of 10-2. Aragonite dissolution rates ranged from 12.77 mmolcm-2s-1 to 13.78 mmolcm-2s-1. The column water reached saturation with respect to calcite in approximately seven days. However, no calcite precipitation was observed by measuring the Sr/Ca, even after seeding the columns with calcite crystals.
Advisors/Committee Members: Boardman, Mark.
Subjects: Geology; Geochemistry
Keywords: aragonite; calcite; diagenesis; ooids; laboratory study; aragonite dissolution; calcite precipitation; strontium; calcium
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12.
Cyr, Andrew J.
GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAU.
Degree: MS, Geology, 2004, Miami University
► Comprehensive analysis of lacustrine carbonates from the Eocene-Oligocene Fenghuoshan Group, north-central Tibet,…
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▼ Comprehensive analysis of lacustrine carbonates from the Eocene-Oligocene Fenghuoshan Group, north-central Tibet, allows interpretation of the paleolimnology and paleoaltitude of the north-central Tibetan Plateau during the mid-Tertiary. Sedimentologic evidence suggests carbonate deposition occurred in shallow lacustrine systems. Stable O and C isotopic analysis of Fenghuoshan carbonates show δ18O values ranging from –11.7‰ to –10.26 (PDB), and δ13C values between –7.13‰ and –2.22‰ (PDB). Poor correlation between these isotopic systems (r2 = 0.0219)suggests open lakes during carbonate deposition. Mineralogy and Mg/Ca ratios indicate fresh water conditions. XRD and Mg/Ca data combined with δ18O values and petrography show little diagenetic alteration. These data indicate that the oxygen isotopic composition of Fenghuoshan carbonates represents the oxygen isotopic composition of meteoric water feeding Fenghuoshan lakes at the time of deposition. Oxygen isotope fractionation model calculations using this meteoric water composition indicate the hypsometric mean elevation of basins feeding Fenghuoshan lakes was ~2 km.
Advisors/Committee Members: Currie, Brian S.
Subjects: Geology
Keywords: Tibet; Fenghuoshan; paleoelevation; lacustrine carbonate; stable isotope geochemistry
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13.
Dark, Joshua Peter.
Reservoir Characterization of the Mid-Cretaceous Dakota Formation, Southern Uinta Basin, Utah.
Degree: MS, Geology, 2008, Miami University
► In the southern Uinta Basin of eastern Utah, fluvial channel sandstones of…
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▼ In the southern Uinta Basin of eastern Utah, fluvial channel sandstones of the Albian-Cenomanian Dakota Formation are economic gas reservoirs. Recovery of gas from the Dakota Formation has proven challenging due to local variability in reservoir sandstone thickness, distribution, and quality. To evaluate the physical characteristics of potential reservoir sandstones, I have constructed two photomosaics of Dakota Formation fluvial channel complexes, measured 13 vertical sections with accompanying outcrop gamma-ray logs, and recorded 1,100 paleocurrent orientations along approximately 40 kilometers of outcrop exposure. Outcrop data were compared with subsurface geophysical/petrophysical and production data to evaluate possible ties between channel sandstone attributes and hydrocarbon occurrence.The primary controls of economic gas accumulation within the Dakota Formation are structure and channel sandstone distribution. Secondary controls include diagenesis and lithology. Amalgamated channels in the lower portions of the Dakota Formation have the greatest potential for economic gas production.
Advisors/Committee Members: Currie, Brian.
Subjects: Geology
Keywords: lithology, sedimentology, sandstone diagenesis, fluvial channel sandstone
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14.
Dice, Derek W.
GEOCHEMISTRY OF THE PLEISTOCENE AQUIFER, NORTHEASTERN ANDROS ISLAND, BAHAMAS.
Degree: MS, Geology, 2003, Miami University
► In this study, the geochemistry and mineralogy of several rock cores from…
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▼ In this study, the geochemistry and mineralogy of several rock cores from the upper 12 meters from Andros Island were evaluated along with water samples collected at specific depths from within the aquifer. Mineralogy was determined by x-ray diffraction, and the elemental composition (major and minor elements) was examined in selected rock samples by DCP spectrometry. The elemental composition of the groundwater was determined by DCP spectrometry, high-performance liquid chromotography, and in-situ pH. By comparing the Ca/Sr ratios of both the groundwater and the limestone along with saturation states of the groundwater, we concluded that dissolution was the dominant process operating in the upper, freshwater lens. By linking petrology, rock geochemistry, water geochemistry, and the location of sea-level, we were able to gain a better understanding of the progress and stages of diagenesis that are presently ongoing in this Pleistocene aquifer.
Advisors/Committee Members: Boardman, Mark.
Subjects: Geology
Keywords: Limestone, Diagenesis, Bahamas, Geochemistry
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15.
Foley, Jeffrey A.
The use of optimization methods-and thermodynamic implications-in mineraology.
Degree: PhD, Geology, 2001, Miami University
► This research has been bound together by one common theme: optimization. Chapters…
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▼ This research has been bound together by one common theme: optimization. Chapters one and two are examples of traditional crystal structure refinements. Chapter three explains the site assign problem and documents a new approach to the problem. Chapter four extends the method to high temperaturese; chapter five extracts the thermodynamic information found in the site occupancies. The appendix is a user's manual for OCCQP. In chapter one the structure and formula of brackebuschite was redefined. Also, the crystal chemistry of the d 4 Mn 3+ ion in oxygen-based minerals is reviewed. Chapter two presents the refinement of redledgeite. It and its synthetic equivalent are important as a solid-state repository for toxic heavy-metal waste. With chapter three, the traditional methods of determining site occupancies in minerals come in to question. The approach is based on crystal-structure data and chemical analyses of the compound, without making prior assumptions. This method provides the flexibility to evaluate trade-offs inherent in assigning occupancies on the basis of a single criterion. Multiple criteria may be used and their relative importance adjusted interactively. The optimizations yield excellent results. Chapter four builds upon the foundation established in chapter three. This chapter is a reexamination of the cation partitioning of the same spinel used in chapter three. This method led to strikingly different results from the authors of the original study, supporting the general view that spinel undergoes a lambda transition at ~1000K. Chapter five extends the thermodynamic formulations for spinel. Most thermodynamic studies of spinels have focused on simple end-member compositions, meaning only two cations—at most—are distributed among the octahedral and tetrahedral sites. This chapter considers a 2-3 spinel having three cation species and vacancies. The standard thermodynamic technique is to consider migration of cations between octahedral and tetrahedral positions as reactions. The stability coefficient D K gives the changes in Gibbs free energy of distribution, and statistical mechanics yields the entropy of distribution.
Advisors/Committee Members: Hughes, John.
Subjects: Geology
Keywords: optimization; thermodynamic; mineralogy; geology
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16.
Ghikas, Constandina Anastasios.
STRUCTURE AND TECTONICS OF A SUBOPHILITIC MÉLANGE (ZAVORDAS MÉLANGE) OF THE VOURINOS OPHIOLITE (GREECE) AND KINEMATICS OF OPHIOLITE EMPLACEMENT.
Degree: MS, Geology, 2007, Miami University
► This thesis describes the lithology, structure, and tectonics of the Zavordas mélange,…
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▼ This thesis describes the lithology, structure, and tectonics of the Zavordas mélange, which occurs structurally beneath the Jurassic Vourinos ophiolite in Northern Greece. This ophiolite is part of the Dinaride-Hellenide ophiolite belt developed during collapse of a Mesozoic marginal basin (Pindos basin) in the western termination of Neotethys. The main focus of the study was to document the lithology of the mélange, its spatial and temporal relationship to the ophiolite and underlying basement, and its history of accretion and obduction onto the continental margin. Research techniques included thematic mapping, structural and petrographic analysis of the mélange units and adjacent rocks, and tectonic reconstructions. The Zavordas mélange contains rift-related volcanic and sedimentary rocks in a pebbly mudstone matrix and displays lower greenschist to amphibolite facies metamorphic grades. The structural fabric in the mélange units indicates tectonic transport to the NE (ophiolite emplacement) overprinted by dextral-slip deformation (Apulian collision), in the Cenozoic.
Advisors/Committee Members: Dilek, Yildirim.
Subjects: Geology
Keywords: mélange, ophiolite, Hellenide, Vourinos
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17.
Guthrie, Kristin M.
STRUCTURAL CONTROLS ON EXTENSIONAL-BASIN DEVELOPMENT,TRIASSIC ISCHIGUALASTO FORMATION, NW ARGENTINA.
Degree: MS, Geology, 2005, Miami University
► This thesis reports the results of a structural and stratigraphic field study…
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▼ This thesis reports the results of a structural and stratigraphic field study of the Ischigualasto Formation in the Ischigualasto Basin, NW Argentina. Previous stratigraphic investigations have documented an along-strike increase in Ischigualasto Formation thickness of ~275 m over a distance of 7 km. While this thickness change has been attributed to syndepositional faulting, the exact location and characteristics of controlling faults have never been documented. In order to determine the influence of fault-related accommodation development on thickness variations in the Ischigualasto Formation a detailed structural mapping project was conducted in the eastern part of the basin. Field mapping identified two groups of intrabasinal normal faults with near perpendicular strike azimuths. These fault orientations, and their calculated extension directions, are best explained by the development of basin-margin perpendicular release faults coupled with normal-sense reactivation of preexisting basement structures. Calculation of cumulative observed displacements along intrabasinal normal faults in the study area, however, revealed a negligible contribution to accommodation. The presence of interpreted release faults in the study area, however, suggests that observed changes in Ischigualasto Formation thickness were controlled by a northwest increase in basin-bounding fault displacement during the time of deposition.
Advisors/Committee Members: Currie, Brian S.
Subjects: Geology
Keywords: Argentina; Ischigualasto; structural geology; sedimentation in rift basins; normal faults; basin-bounding fault systems
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18.
Hecker, Joel W.
QUANTIFYING RECHARGE DURING THE LAST GLACIAL MAXIMUM IN THE DEATH VALLEY REGIONAL FLOW SYSTEM.
Degree: MS, Geology, 2012, Miami University
► Paleo-hydrologic surface deposits signify wetter than present conditions during the Last Glacial…
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▼ Paleo-hydrologic surface deposits signify wetter than present conditions during the Last Glacial Maximum (LGM) in the American Southwest. Detailed knowledge exists about the location of these surface deposits, as well as the climate and hydrologic conditions during the LGM. Using groundwater modeling programs in conjunction with paleohydrologic deposits allowed for an opportunity to quantitatively characterize past climate for a 100,000 km2 area near Death Valley, approximating recharge and the level of the potentiometric surface. Simulations using the Death Valley Regional Flow System model indicated that the average recharge rate in the model domain during the LGM was approximately 1.63 cm/yr, or 7.71 times the calibrated modern recharge rate. As a result, the simulated potentiometric surface was generally 0-50m higher throughout the model domain. Assuming LGM precipitation was twice the modern value (Forester et al., 1999), ~6.80% of total precipitation became recharge during the LGM, compared to only ~1.75% during modern day.
Advisors/Committee Members: Rech, Jason.
Subjects: Geological; Geology; Hydrologic Sciences; Hydrology
Keywords: Death Valley Regional Flow System; Recharge; Last Glacial Maximum; Las Vegas; Potentiometric Surface; Water
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19.
Hinojosa-Prieto, Hector R.
Subduction zone-related Nonvolcanic Tremor in Oaxaca, Mexico.
Degree: MS, Geology, 2009, Miami University
► The Oaxaca subduction zone is ideal for studying plate boundary deformation as…
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▼ The Oaxaca subduction zone is ideal for studying plate boundary deformation as rapid convergent rates, shallow subduction, and short trench-to-coast distances bring the seismogenic and transition zones of the plate interface over 100 km inland. A new deployment of 7 seismometers is used to examine whether non-volcanic tremor (NVT) signals can characterize the boundary between the seismogenic and transition zones. This study finds NVT exists in Oaxaca based on emergent seismic energy, narrow frequency spectra, and appropriate relative timing. Prominent days-to-week-long episodes during the 15 months analyzed recur every 2-2.5 months in a given region, but at different times in the east and west. Waveforms analyzed with a semi-automated process for identifying source locations find NVT near the 45-km contour for plate interface depth, correlated with high conductivity interpreted to be slab fluids, and just downdip from slow slip and ultra-slow velocities interpreted to represent high pore fluid pressure.
Advisors/Committee Members: Brudzinski, Michael.
Subjects: Geophysics
Keywords: Nonvolcanic Tremor, Transition zone, Oaxaca region, Mexican subduction zone
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20.
Jaisi, Deb Prasad.
Fe(III) reduction in clay minerals and its application to technetium immobilization.
Degree: PhD, Geology, 2007, Miami University
► The iron redox biogeochemistry, especially in clay minerals, is poorly understood. As…
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▼ The iron redox biogeochemistry, especially in clay minerals, is poorly understood. As a result, applicability of this redox reaction or the products to environmental problems such as remediation of metal contaminants is largely unexplored. This dissertation, therefore, seeks to develop a fundamental understanding of bacterial Fe(III) reduction in clay minerals and reactivity of resulting Fe(II) in reducing and immobilizing technetium (99Tc). The first subproject involves research on iron biogeochemistry in different clay minerals [nontronite (NAu-1, NAu-2), Muloorina illite (Mu-Il) and chlorite (CCa-2)]. The results reveal that the extent of Fe(III) reduction depends on the difference in the crystal structure, layer charge and Fe(III) content. Among different Fe(III) species, Fe(III) in the tetrahedral site is the most reducible and that in the cis-octahedral sites the least. Fe(II) produced from Fe(III) reduction speciates into four chemical environments in clay minerals: aqueous, structural, complexed to amphoteric surface sites and at exchangeable sites. The Fe(II) sorbed both to cell and mineral surfaces exerts a strong inhibitory effect for further Fe(III) reduction. The interplay of these factors can be modeled by considering the reactive surface site concentration, surface saturation, Fe(II) production and its surface inhibition. The second subproject involves the use of Fe(II), produced from microbial and chemical reduction of Fe(III) in nontronite, for the long-term immobilization of technetium, a significant contaminant in several U.S. DOE sites. The Fe(II) at different chemical environments in reduced nontronite (NAu-2) is found to reduce Tc(VII) into Tc(IV) with the following order of decreasing relative reactivity: Fe(II) at surface complexation sites >> Fe(II) at exchangeable sites > Fe(II) at structural sites. EXAFS results suggest that ~70% of Tc(IV) is surface precipitated and the rest forms surface complex with NAu-2. Because the reduced Tc(IV) is associated with clay particle aggregates, it is very recalcitrant to reoxidation in the presence of thermodynamically more favorable electron acceptors/oxidants such as oxygen, nitrate, Fe(III) and Mn(III/IV) oxides. Since the clay aggregates are relatively stable and are less likely perturbed by any transient changes in the aquifer geo-, hydro- and biochemistry, these findings may provide an important step toward the long term immobilization of Tc.
Advisors/Committee Members: Dong, Hailiang.
Subjects: Geology
Keywords: Fe(III) reduction, clay minerals, aggregation, Tc(VII) reduction, long-term immobilization
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21.
Jiang, Hongchen.
GEOMICROBIOLOGICAL STUDIES OF SALINE LAKES ON THE TIBETAN PLATEAU, NW CHINA: LINKING GEOLOGICAL AND MICROBIAL PROCESSES.
Degree: PhD, Geology, 2007, Miami University
► Lakes constitute an important part of the global ecosystem as habitats in…
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▼ Lakes constitute an important part of the global ecosystem as habitats in these environments play an important role in biogeochemical cycles of life-essential elements. The cycles of carbon, nitrogen and sulfur in these ecosystems are intimately linked to global phenomena such as climate change. Microorganisms are at the base of the food chain in these environments and drive the cycling of carbon and nitrogen in water columns and the sediments. Despite many studies on microbial ecology of lake ecosystems, significant gaps exist in our knowledge of how microbial and geological processes interact with each other. In this dissertation, I have studied the ecology and biogeochemistry of lakes on the Tibetan Plateau, NW China. The Tibetan lakes are pristine and stable with multiple environmental gradients (among which are salinity, pH, and ammonia concentration). These characteristics allow an assessment of mutual interactions of microorganisms and geochemical conditions in these lakes. Two lakes were chosen for this project: Lake Chaka and Qinghai Lake. These two lakes have contrasting salinity and pH: slightly saline (12 g/L) and alkaline (9.3) for Qinghai Lake and hypersaline (325 g/L) but neutral pH (7.4) for Chaka Lake. We have taken an integrated approach combining geochemistry, molecular phylogeny (both DNA and RNA based, both 16S rRNA and amoA gene), quantitative PCR (total Bacteria, Archaea, total crenarchaeota, AOA, and AOB), and cultivation and isolation. Both lake water and sediments have been analyzed. The results are divided into four chapters and they are summarized below. In addition, I also studied microbial communities and functions in sediments from South China Sea, a potential site for gas hydrate deposits. This work was done as extra add-on to the microbial ecology studies in Titeban lakes.
Advisors/Committee Members: Dong, Hailiang.
Keywords: Geomicrobiology; Tibetan Plateau; Saline lakes
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22.
Karel, Patrick Robert.
Seismic Analysis of the Tonga Subduction Zone and Implications on the Thermo-Petrologic Evolution of Deep Subduction.
Degree: MS, Geology, 2011, Miami University
► Utilizing waveform analysis, we show the subhorizontal leading edge (“toe”) of the…
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▼ Utilizing waveform analysis, we show the subhorizontal leading edge (“toe”) of the Wadati-Benioff zone (WBZ) of the Tonga subduction zone displays petrologic and petrofabric anomalies. While it appears connected to the WBZ, sporadic fault plane solutions require a localized stress for the deep seismicity. High P-wave speeds (~3%) are absent in the seismogenic toe, requiring a petrologic anomaly to counteract low temperature, and considerable SH-SV splitting implies an anisotropic petrofabric anomaly. The same observations were previously documented for shallower outboard earthquakes in the transition zone extending over 1,000 km further west. Hence, these shared properties represent stages in deep subduction, the toe preceding a large-scale detachment of lithosphere. Metastable olivine satisfies all available observations, accounts for buoyant lithosphere in the transition zone, discouraging slab penetration, and provides a mechanism for deep seismicity. Rising temperature leaves only a thermal anomaly, as seen south of the toe and elsewhere in the Pacific.
Advisors/Committee Members: Brudzinski, Michael.
Subjects: Geology; Geophysics
Keywords: Tonga; subduction; anisotropy; waveform analysis; deep earthquakes; discontinuity; transition zone; metastable olivine
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23.
Losey, Arthur Bill.
STRUCTURAL VARIATION IN THE PHOSPHATE OLIVINE LITHIOPHILITE-TRIPHYLITE SERIES AND CHARACTERIZATION OF LIGHT ELEMENT (Li, Be, AND B) MINERAL STANDARDS.
Degree: MS, Geology, 2002, Miami University
► This research is comprised of two projects involving the use of single…
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▼ This research is comprised of two projects involving the use of single crystal X-ray diffraction to for mineral structure determination. Chapter 1 involves determination of structural variation along the Mn ⇔ Fe solid solution of the lithiophilite-triphylite series, olivine structure types. Bond lengths and angle variance are examined to determine their variation along the Mn ⇔ Fe join and their relationships to other silicate and germanate olivine structures. The angle variance of the phosphate olivines was smaller in the M1 octahedron, which is in contrast to the other olivine structure phases examined in this study. In Chapter 2, diffraction data were collected on phenakite, danburite, spodumene, hambergite, lithiophilite, axinite, and prismatine, which are to be used as light element (Li, Be, and B) mineral standards. The data were used to determine the atomic positional parameters, site geometry, site occupancy, and polyhedral connectivity of each sample. This research is comprised of two projects involving the use of single crystal X-ray diffraction to for mineral structure determination. Chapter 1 involves determination of structural variation along the Mn ⇔ Fe solid solution of the lithiophilite-triphylite series, olivine structure types. Bond lengths and angle variance are examined to determine their variation along the Mn ⇔ Fe join and their relationships to other silicate and germanate olivine structures. The angle variance of the phosphate olivines was smaller in the M1 octahedron, which is in contrast to the other olivine structure phases examined in this study. In Chapter 2, diffraction data were collected on phenakite, danburite, spodumene, hambergite, lithiophilite, axinite, and prismatine, which are to be used as light element (Li, Be, and B) mineral standards. The data were used to determine the atomic positional parameters, site geometry, site occupancy, and polyhedral connectivity of each sample.
Advisors/Committee Members: Rakovan, John.
Keywords: angle variance; M2 site; M1; lithiophilite-triphylite; olivine structure
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24.
Luo, Yun.
Crystal Chemistry of U and Th in Apatite.
Degree: PhD, Geology, 2010, Miami University
► Understanding the crystal chemistry of actinides in nuclear waste forms is critical…
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▼ Understanding the crystal chemistry of actinides in nuclear waste forms is critical for the evaluation of the material’s potential use and stability as solid state waste repositories. Because of the ability of apatite to incorporate lanthanides and actinides there is great interest in the phase as a solid nuclear waste form. However, the crystal chemistry of U and Th in the apatite structure is still poorly understood. This dissertation investigates the structural crystal chemical parameters in a variety of natural and synthetic apatites with substituent U and Th through the complimentary use of single crystal X-ray diffraction and X-ray absorption spectroscopy. 1) Site preference of U and Th in F, Cl, Sr apatites, investigated the site preference of U and Th and the structural response to these substituents in a series of synthetic fluor-, chlor-, and strontium-apatite crystals using single crystal X-ray diffraction. 2) Crystal chemistry of Th in fluorapatite, obtained quantitative information of the local structure of Th in both natural and synthetic fluorapatite by Extended X-ray absorption fine-structure spectroscopy (EXAFS). Understanding the mechanism of incorporation and the structural response of fluorapatite to Th is important in assessing the use of apatite as a possible host for tetravalent radionuclides and understanding the behavior of Th in geological systems where fluorapatite is present. 3) Orientation dependent polarized micro-XAS study of single crystal apatite, developed the technique/equipment to accommodate polarization effects of synchrotron radiation on single crystal apatites. A goniometer was designed for precise positioning of single crystals for microXAS data collection. Lattice orientation is determined from X-ray diffraction data and then can be applied to EXAFS data analysis. The outcome of this technique development will have application to many other studies with similar sample constraints.
Advisors/Committee Members: Rakovan, John.
Subjects: Mineralogy
Keywords: apatite; fluorapatite; uranium; thorium; single crystal XRD; X-ray absorption spectroscopy; XANES; EXAFS; micro-XAS; orientation dependent; polarization
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25.
Meng, Qing.
Geochemistry and Sr-Nd-Pb-Os isotope systematics of peridotites from the Sulu ultrahigh-pressure metamorphic belt, Eastern China.
Degree: MS, Geology, 2009, Miami University
► We have performed Sr-Nd-Pb and Re-Os isotope studies on 13 peridotites from…
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▼ We have performed Sr-Nd-Pb and Re-Os isotope studies on 13 peridotites from the pre-pilot hole (PP1) of the Chinese Continental Scientific Drilling. 187Os/188Os ratios (0.11163 - 0.12065) indicate that the peridotites are derived from an ancient depleted mantle source. The oldest Re-depletion age (2.43 Ga) indicates that the peridotites originate from the remnants of Archean continental lithospheric mantle from the North China Craton. The Sr-Nd-Pb data indicate that the peridotites were strongly affected by fluid/melts derived from subducted lower Yangtze crust during ultrahigh pressure metamorphism and subsequent recrystallization. The peridotites can be divided into two groups according to the correlations between 187Os/188Os and Al2O3. The Re-Os isotope systematics of Group A were not significantly affected by any metasomatic events, whereas those of Group B were affected by a fluid/melt that formed a phlogopite vein.
Advisors/Committee Members: Widom, Elisabeth.
Subjects: Geochemistry
Keywords: Re-Os isotopes; peridotites; Sulu; China; UHP metamorphism; mantle metasomatism
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26.
Mitchell, Beth Louise.
Characterization of the Physical, Chemical, and Biological Factors that Control the Fate and Transport of Bacteria through Glacial-Outwash Sediments.
Degree: MS, Geology, 2006, Miami University
► This study investigated the effects of sediment grain size distribution, mineralogy and…
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▼ This study investigated the effects of sediment grain size distribution, mineralogy and surface charge, and bacterial surface charge on bacterial transport through natural porous media. Bacterial flow-through experiments were conducted using three intact heterogeneous sediment cores. Sediments were characterized for their physical and chemical properties. The surface charge of the suspended bacteria in the influent and effluent was also measured. Results indicated that the presence of dolomite was significant to the fractions of retained bacteria. Surface charge of the effluent bacteria results indicated that the attractive forces between the sediments and bacteria were significant to bacterial transport. The overall results of this study indicate that degree of sorting, presence of carbonates, and surface charge of the bacteria are all related to the number of retained bacteria.
Advisors/Committee Members: Levy, Jonathan.
Subjects: Geology
Keywords: bacterial transport electrophoresis bacteria surface charge dolomite
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27.
Mutiti, Samuel.
Assessing the Potential for Using LANDSAT Image-Derived Spectral Properties to Explore for Ground Water in Kenya and Investigation of Riverbed Dynamics and Temperature Modeling: Scour, Deposition and Temporal Variability of Hydraulic Conductivity.
Degree: PhD, Geology, 2009, Miami University
► In this dissertation, two issues that deal with access to clean drinking…
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▼ In this dissertation, two issues that deal with access to clean drinking water were addressed. The first issue focused on the development of inexpensive ways to assess the potential for increasing groundwater supplies in a rural semi-arid region. The study area was in southeast Kenya in an area that is dependent on surface water collected in catchments on the mountain. The area experiences severe water shortages, especially during drought periods. In recent years, remote sensing has emerged as an inexpensive tool in groundwater exploration. In this study, LANDSAT imagery, which is relatively cheaper, was successfully used to map relative topography, moisture and vegetation. Together with linear features, soil types, and rock data, these features were used to identify areas with shallow groundwater potential. The areas were checked for depth to water table and subsurface lithology, with the water table being between 3 and 11 m.The second issue focused on assessing the effect of storms on riverbed sediments and hydraulic conductivity (Kv). Despite studies showing significant reductions in microbial contamination by riverbank filtration, there still exists some uncertainty in determining a site’s susceptibility to contamination from river water. This research quantified variations in riverbed Kv during storms using temperature modeling. Study sites were associated with municipal production wells along the Great Miami River. Kv increased by up to an order of magnitude from pre-storm low values to the largest Kv, with a maximum value for the study period of about 0.06 m/d. There was a positive correlation between the factor of increase and the time it took for stage to rise to its peak value, with an adjusted R2 = 0.76 and a p-value = 0.03. Riverbed scour was measured using a load-cell sensor and scour chains. The amount of scour occurring during any given storm was correlated with changes in the river stage with an adjusted R2 = 0.71 and a p-value = 0.0014. A comparison of the dimensionality of model domains revealed that a 2D model domain was more appropriate than a 1D domain at all sites of induced infiltration. The 1D model tended to over-estimate Kv value.
Advisors/Committee Members: Levy, Jonathan.
Subjects: Hydrology
Keywords: Ground Water; Temperature Modling; Remote Sensing; Hydrogeology
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28.
ONER, ZEYNEP.
Supradetachment Basin Tectonics and The Exhumation History of The Menderes Core Complex, Western Anatolia - Turkey.
Degree: PhD, Geology, 2012, Miami University
► Supradetachment basins are asymmetric extensional depocenters that develop in the hanging walls…
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▼ 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.
Advisors/Committee Members: Dilek, Yildirim.
Subjects: Geochemistry; Geological; Geology; Sedimentary Geology
Keywords: Extensional tectonics; Supradetachment basin; Metamorphic core complex; Uplift and exhumation history; western Anatolia,Turkey
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29.
Partey, Frederick Kenneh.
SOURCE OF FLUORINE AND PETROGENESIS OF THE RIO GRANDE RIFT TYPE BARITE-FLUORITE-GALENA DEPOSITS.
Degree: MS, Geology, 2004, Miami University
► Abundant fluorite mineralization in Rio Grande Rift (RGR) barite-fluorite-galena deposits is anomalous…
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▼ Abundant fluorite mineralization in Rio Grande Rift (RGR) barite-fluorite-galena deposits is anomalous compared to typical Mississippi valley type deposits to which they have been compared, and the source of the fluorine in these deposits is controversial. In this study we used chlorine isotopes to test the possibility of an asthenospheric source of fluorine in the RGR deposits. Chlorine was used as proxy for determining the source of the fluorine because chlorine, unlike fluorine, has more than one isotope and thus can be used as an isotopic tracer. Chlorine and fluorine exhibit chemically similar behavior, and therefore are likely to be derived from the same source if associated with rift related magmatism. Complimentary to chlorine isotopic studies, Br/Cl ratios were also measured from the fluorite fluid inclusions and applied as additional tracers. Sr and Nd isotopes were measured from fluorites, granites, carbonates, and asthenospheric basalts to aid in understanding the petrogenesis of RGR deposits.
Advisors/Committee Members: Rakovan, John F.
Subjects: Geology
Keywords: Rio Grande Rift; Cl isotopes; Fluorites; Sr and Nd isotopes
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30.
Phillips, Charity M.
Seafloor Spreading Processes in Protoarc-Forearc Settings: Eastern Albanian Ophiolite as a Case Study.
Degree: MS, Geology, 2004, Miami University
► Northern Albania's Mirdita ophiolite displays two distinct belts of Jurassic Neotethyan oceanic…
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▼ Northern Albania's Mirdita ophiolite displays two distinct belts of Jurassic Neotethyan oceanic crust that developed between the Apulian and Pelagonian margins. The western belt consists of an ~3-km-thick MORB pseudostratigraphy, in which pillow lavas overlie serpentinized peridotites, suggesting tectonic extension dominated early stages of seafloor spreading. The eastern belt includes an ~10-km-thick complete pseudostratigraphy with extrusives that show increasing IAT chemistry upsection. Mutually intrusive relations between crustal units indicate robust magmatic spreading occurred. Four dike generations (D1-D4) exist based on structure, crosscutting relations, and texture. D1-D4 are composed of diabase dikes. D1 strike 030-060o, dips SE, and is crosscut by NE dipping D2 dikes oriented 290-340o. D3-D4 crosscut D1-D2 and strike of 240-290o with northerly dips. Boninite and rhyodacite dikes intruded throughout the SDC's history because of complex magmatic processes. These relations suggest the spreading direction changed from NNE-SSW to NW-SE because of the incipient Mirdita-Pelagonia collision in the South.
Advisors/Committee Members: Dilek, Yildirim.
Subjects: Geology
Keywords: seafloor spreading; forearc; Albania; ophiolite; Mirdita; dike; quartz diorite; Apulia; Pelagonia
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