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Origin And Tectonic Evolution Of The Southern Appalachian Neoacadin Crystalline Core: Evidence From The Geology Of The Gilreath 7.5-Minute Quadrangle, North Carolina, Crystal Gayle Wilson

Masters Theses

Detailed geologic mapping of the Gilreath 7.5-minute quadrangle recognizes the northernmost continuation of the Brindle Creek fault, a terrane boundary that separates Neoproterozic-Ordovician metasedimentary and metavolcanic rocks of the western Tugaloo terrane (western Inner Piedmont) from Silurian-Devonian metasedimentary rocks and Devonian-Mississippian anatectic granitoids of the Cat Square terrane (eastern Inner Piedmont). The Brindle Creek fault is folded in the study area and exposes the Ordovician Brooks Crossroads Granite in a reentrant. Low high-field strength element concentrations and a flatter rare earth element patterns typical of western Inner Piedmont granitoids, support a footwall setting for the Brooks Crossroads Granite.

New geochemical …

Petrogenesis Of Apollo 15 Olivine-Normative And Quartz-Normative Mare Basalts, Darren W. Schnare

Masters Theses

New data are presented for four Apollo 15 low-Ti mare basalts, two from the olivine-normative suite (15106, and 15555) and two from the quartz-normative suite (15475, and 15499). Previous studies have examined the relationships between these groups on the basis of whole-rock chemistry, many with analyses that may have been of insufficient sample-size, or of limited range of elements analyzed. To determine a relationship between these basalts, these samples have been analyzed for their mineral major-element and trace-element compositions by electron-microprobe and laser-ablation inductively-coupled-plasma mass-spectrometry, respectively.

The trace-element compositions of the main silicate phases, olivine, pyroxene, and plagioclase, are consistent …

Biomarker And Stable Isotope Characterization Of Coastal Pond Organic Matter, Mcmurdo Dry Valleys, Antarctica, Melissa Margaret Hage

Masters Theses

Small coastal ponds containing photosynthetic microbial mat communities represent a potentially significant source of labile organic carbon within the McMurdoDryValleys, Antarctica. To distinguish coastal pond derived organic matter (CPDOM) from other sources of organic matter in the dry valleys, I investigated bulk organic carbon and nitrogen isotopic signatures and phospholipid fatty acid (PLFA) profiles of benthic microbial mats located at two sites, HjorthHillCoastand GarwoodValley. The average δ¹³C values at Hjorth Hill Coast and Garwood Valley are -10.91 ‰ and -10.19 ‰, respectively. The average δ¹⁵N values are 3.73 ‰ and -1.25 ‰, respectively. Microbial mats from …

Pyrogenic Polycyclic Aromatic Hydrocarbons From Carboniferous, Triassic, And Modern Chars: Potential Relations To Paleoatmospheric Oxygen Content, Patrick Jerome Schuneman

Masters Theses

Atmospheric oxygen concentrations may have dramatically fluctuated throughout the Phanerozoic. Because oxygen is critical to fire, major oxygen fluctuations may have significantly affected biomass burning occurrences, suggesting that wildfires would have been more prevalent at times of elevated oxygen. Fossil charcoal abundances in the geologic record qualitatively reflect this relationship. Land plants evolved by the late Silurian, and the earliest true forests evolved by the mid-Devonian, while oxygen levels were still low. Fuel accumulations and oxygen content probably did not reach sufficient levels to sustain burning until the late-Devonian. There are only one or two isolated examples of fossil charcoal …

A Quantitative Study Of Scaling Properties Of Fracture Networks, Ankur Roy

Masters Theses

Fracture networks and their scaling properties are important from both an academic and practical perspective since they play a significant role in many areas ranging from crustal fluid flow to studies of earthquakes. Over the years, researchers have employed a wide variety of techniques to quantify the complexities of fractured media. These range from deterministic, process-based approaches employing the laws of physics, to ones involving the applications of geostatistics and more recently, fractal geometry. Fractals are irregular entities that show self-similarity over a wide range of scales and can be quantified by the fractal dimension, D. It is important …

Mechanisms For Increasing Respiratory Capacity Through Ontogeny In The Blastoid Genus Pentremites, Troy A. Dexter

Masters Theses

This study was conducted to determine how the hydrospires in blastoids (the respiratory channels through which blastoids respire) change in shape and capacity during ontogeny. As the volume of a blastoid increases ontogenetically, the respiratory capacity of the hydrospires must increase to match the additional respiratory requirements. Ontogenetically, volume increases at a cubic rate, therefore the surface area of the respiratory structures should increase at a similar rate. Using transverse cross sections of the theca through an ontogenetic series in two species of the blastoid Pentremites, the surface area and volume of the hydrospires was quantified. The data demonstrated …

Geochemical Characterization Of Coastal Pond And Adjacent Soil Organic Matter From Two Distinct Field Areas Of The Mcmurdo Dry Valleys, Antarctica, Meg E. Howard

Masters Theses

The McMurdo Dry Valleys (MDV), Antarctica contains some of the few ice-free oases on the continent, and is one of the coldest, driest places on earth. Despite the harsh conditions, the MDV supports an abundance of biological communities within soil and aquatic systems. Bioavailable carbon is present in these systems in the form of ancient and modern sources. An additional source of bioavailable carbon that has largely been ignored may be represented by desiccated and disseminated microbial mats (coastal pond organic matter, or CP-OM) originating in ephemeral coastal meltwater ponds of the MDV. The goal of this study is to …

Hydrothermal Diamond Anvil Cell Studies: A Possible New Calibration Mineral And Applications To The Hydrous-Carbonate Mineral, Nesquehonite., Cara Kim Mulcahy

Masters Theses

In this study, modifications are made to the experimental setup of the Bassett-type hydrothermal diamond anvil cell facilities at the University of Tennessee. Several modifications to the HDAC setup were found to increase the number of successful experimental runs by reducing fluid loss: ·

Gaskets were no longer polished or only lightly polished using 1µm diamond polishing compound. This prevented the formation of a wedge-shaped gasket. ·

Gasket diameter was reduced to equal the diameter of the diamond anvil surface to prevent “tipping” of the gasket and the possible introduction of foreign material between the gasket and diamond anvils.

Sample …

Contact Metamorphism Of Calc-Silicate Rocks In The Belmont Contact Aureole, Central Nevada, Kelly Plummer

Masters Theses

This study focuses on the contact metamorphism of the Ordovician Zanzibar and Toquima Formations by the Cretaceous Belmont Pluton in central Nevada. I mapped the distributions of tremolite and diopside to determine the location of isograds. These isograds are the result of the reactions: 8 quartz + 5 dolomite + H₂O = 3 calcite + tremolite + 7 CO₂ and tremolite + 2 quartz + 3 calcite = 5 diopside + 3 CO₂ + H₂O. Pressure of metamorphism is estimated at between 4 kbar and 1 kbar, but is not definite because of uncertainty …

Origin And Classification Of Middle Wallace Breccias, Mesoproterozoic Belt Supergroup, Montana And Idaho, Quintin M. Overocker

Masters Theses

A series of enigmatic breccias in the Wallace Formation, Mesoproterozoic Belt Supergroup, have been variously interpreted as originating from: (1) syndepositional downslope slumping; (2) syndepositional evaporite dissolution and collapse; or (3) post- depositional tectonic faulting. Each hypothesis carries its own implications regarding the depositional and diagenetic history of the Belt basin. Examination of several Middle Wallace breccia outcrops suggests that they can be grouped into two distinct categories based on size of breccia bodies, clast size, and relationships with surrounding strata, and matrix composition. Results indicate that rather than a single origin, these two breccia groups originate from distinctly different …

Investigating The Origin Of Precambrian Molar-Tooth Carbonate, John Curtis Crawford

Masters Theses

Molar-Tooth (MT) is an enigmatic carbonate structure that consists of a complex array of variously shaped voids filled with an unusual microspar cement. Most current research has been focused on the mechanism of formation of molar-tooth voids, and the leading model suggests a subsurface, soft-sediment, gas escape mechanism. However, little is known about the calcite microspar that fills MT voids. Brittle deformation of MT structures during sediment compaction indicates that lithification of MT voids is essentially synsedimentary. Under cathodoluminescence (CL) microscopy, MT microspar appears as small (3-12 µm), spheroidal to rhombic, non- luminescent cores surrounded by luminescent, isopachous overgrowths. Crystal …