Three islands of study with differing types of dolomite were examined for karst features. Barbados showed that island dolomite could contain dissolutional karst features that form either during or after dolomitization. On Curacao, two types of dolomite were identified. The first documented occurrence of direct dolomite precipitation in situ was found using electron microscopy. Remnant voids from Curacao were classified and used to determine uplift and cliff retreat rates. On Isla de Mona, the influence of microbes in the mixing zone was added to the Dorag model of dolomite replacement. In addition, accounting for glacioeustasy, tectonic, and diagenetic fluctuations hypothesized large volume of dolomite. This study significantly contributes to the understanding of young dolomite formation and diagenesis as well as documenting dissolutional voids within island dolomite.

This dissertation presents the results of a study performed to investigate methods for increasing the damping capacity of concrete. A variety of additives, both particle and latex based, were added to standard concrete mixtures by replacing up to 20% of the fine aggregate to measure their effects on strength, stiffness, damping, and air content. The additives included rubber particles from recycled tires, calcium carbonate particles, styrene butadiene rubber (SBR) latex, and a commercially available product named ConcreDamp which contains vegetable gum suspended in styrene butadiene latex. An initial investigation resulted in the observation that all of the additives with the exception of the SBR latex would both increase air content and decrease compressive strength. As a result, combinations of additives were investigated to see if both the mechanical and dynamic properties could be improved. The addition of steel fibers to mixtures with ground rubber were found to significantly increase air content which offset any gains in compressive strength. The combination of ground rubber and latex was shown to improve both increase compressive strength and reduce air content. The study advanced to investigate the effects of rubber size on air content, strength, and damping. It was found that for the same volume of rubber, a larger rubber particle would decrease air content, decrease compressive strength, and improve damping. The results of this study show that the best performing additive was the vegetable gum latex which improved the concrete damping by a factor of 2 when added as 15% of the fine aggregate. Additionally, an equation is presented for calculating a strength reduction factor for concrete containing rubber particles of different sizes. Finally, two full scale footbridge laboratory specimens were tested to investigate the effect of increased material damping at the structural level. One footbridge was constructed using a base concrete mixture without damping admixtures. The second was constructed with a concrete mixture that contained a replacement of 15% of the fine aggregate with ground rubber. The results were used to create a finite element model in SAP2000 that was used to predict the effects that high damping concretes would have on the footbridge specimen. / Ph. D.

Page 214 Not included in thesis. / <p> Hydrothermal carbonate was introduced into igneous rock in the Timmins area during an early, sea water alteration event when calcite (δ13C = 0 to -3o/oo) filled the primary porosity of basalt flows and during a later hydrothermal event when mafic and ultramafic igneous rock were altered into a zoned sequence consisting of an inner zone of ferroan or magnesian carbonate flanked by calcite- and chlorite-rich assemblages. The younger intense carbonate alteration event predated or was synchronous with regional metamorphism and deformation and was focused along structurally induced, permeable zones. Gold was introduced during and after the intense carbonate alteration.</p> <p> Away from carbonaceous sediments, δ13C-values of the ferroan carbonate are very uniform (-3.5 to -5o/oo) regardless of stratigraphic position, size, or gold tenor of the alteration zone. As carbonaceous sediments are approached, 13C of the ferroan carbonate becomes upto 4o/oo heavier. The 13C of the CO2 and δ18O and δD of the water components of the hydrothermal fluid are estimated to have been -3 to -6, +5 to +10, and -40 to -60o/oo respectively. The geological controls on the distribution of carbonate alteration, and the stable isotopic values of the hydrothermal components suggest that the H2O-CO2 hydrothermal fluid was of magmatic origin, a result of mantle degassing.</p> / Thesis / Doctor of Philosophy (PhD)

<p> The presence of 0.10 moles/l. of glycine, glutamic acid, aspartic acid or leucine in a saturated bicarbonate solution will promote the formation of aragonitic calcium carbonate at 25.2°C. Magnesium ion, with or without an amino acid, also promotes the formation of aragonite. With increased amino acid concentration glutamic acid and alanine tend to promote the formation of more calcitic calcium carbonate, glycine and valine tend to promote the formation of more aragonitic calcium carbonate. Lysine and alanine show an increased tendency to form calcite at higher ionic strengths (.20) whereas glutamic acid shows the reverse. Some correlation with solubility and equilibrium constants for magnesium-amino acid complexes is indicated.</p> / Thesis / Candidate in Philosophy

The purpose of this thesis is to establish possible changes in the CI/Br ratio of ancient oceans over the past 2 x 10 9 years. Variations in the Cl/Br ratio of carbonate rocks are used to indicate these changes. A secondary objective of this thesis is to determine the distribution patterns of F in limestones and dolomites. Variations in the F content of dolomites are shown to be related to environment of deposition and can be used to establish tho genesis of dolomite. The contents of the thesis include; 1) a comprehensive review of the pertinent literature, 2) a discussion of the evolution of the Cl/Br ratio of the ocean. 3) application of F in paleoenvironmental reconstruction, and 4) suggestions for further research. / Thesis / Doctor of Philosophy (PhD)

No description available.

No description available.

No description available.

Elemental proxy models for temperature and seawater chemistry begin by assuming compositional signatures reflect environmental conditions of formation. The Mg/Ca ratio in marine cements and calcified skeletal structures is a widely used proxy for reconstructing past earth environments. Many studies have positively correlated Mg content in biogenic carbonates with temperature, but it is difficult to differentiate the effect of temperature from other environmental factors. Supersaturation, precipitation rate, salinity, pH, and ion concentration have also been proposed as drivers of Mg/Ca. Furthermore, it is difficult to distinguish environmental signatures from the “vital effect,” or the influences superimposed by the growth needs and metabolic activities of the organism. To construct viable paleoenvironmental proxies from biomineral compositions, we must resolve the effects of environmental conditions from the vital effects of the organism by first understanding the underlying thermodynamic and kinetic mechanisms for incorporating minor and trace elements. Using in situ Atomic Force Microscopy, controlled solution chemistries, and different ion microprobe techniques, this dissertation investigates the kinetics and thermodynamics of calcite growth to establish an inorganic baseline for uptake of Mg. I use this information to quantify the enhancement in Mg/Ca due to the presence of hydrophilic 27-mer peptides, demonstrating a possible origin of vital effects. Likewise I measure the effect of ionic strength on signatures and find that growth rate and background electrolyte proved more important than salinity in determining Mg contents. The findings contribute to the ongoing discussion regarding the relative importance of unique seawater parameters in determining Mg/Ca in calcite. Mg contents are significantly enhanced by biomolecules relative to the amounts attributed to temperature differences, while Mg content is less influenced by salinity variation than by changing supersaturation or driving force. In addition to sorting out the relative importance of environmental factors, our results begin to address the interplay of these different parameters in concert, and at different scales. At sites of calcification, the local biochemistry within an organism may shift in response to more saline waters. At a geological scale, interpreting past temperatures and particularly those of the Last Glacial Maximum depends on our ability to sort out and account for this interplay of salinity and temperature on Mg/Ca. Processes underlying inorganic and biogenic carbonate mineralization and interpretations of their formation environments are better understood by examining the influence of environmental parameters and biomolecular chemistry on kinetics and thermodynamics of calcite growth and stability. / Ph. D.

The Lower Cbazyan (Middle Ordovician) Blackford Formation of the area studied consists of dominantly carbonate rocks deposited in a shallow sea which transgressed on a subaerially eroded carbonate terrane having up to 110 feet of relief locally. The lower two-thirds was deposited in a generally supratidal environment and grades up into rocks deposited in the gradually deepening waters of the intertidal and shallow subtidal environments. The Blackford is divisible into three parts. The lowermost part, which laterally is limited in extent, is a red to purple or yellow green breccia-conglomerate of chert and dolomite clasts in a silty to sandy argillaceous dolomite matrix. The middle part is brownish red to purplish red locally green and mottled, dolomite to dolomitic sandy siltstone. It is locally conglomeratic. It contains algal and faunal debris locally, and varying quantities of terrigenous detritus, including chert and dolomite clasts, rounded quartz grains) quartz crystals, an illite-mica-chlorite clay mineral suite, and a heavy mineral suite characterized by hematite, magnetite and kyanite. This terrigenous detritus dominantly was derived locally, from the unconformably subjacent Canadian (Lower Ordovician) Knox dolomites. The upper part of the Blackford is a sequence of gray to yellowish and greenish gray argillaceous calcilutites to calcareous claystones which grade into the overlying Elway Limestone. This part contains algae algal stromatolites, ostracodes, bryozoa and rare trilobites. Nodular black chert is locally present in the uppermost part. The proportion of coarse clastics and dolomite decreases upward whereas the clay content increases abruptly in the upper beds. The new assemblage is definitely volcanic. Abundant we11 preserved conodonts found with the biotite and apatite are potentially useful for precise paleontologic dating of this volcanism. The volcanic zone in the upper Blackford may be one previously recognized by Laurence in Lower Chazyan rockS at Douglas Dam, Tennessee. The Blackford volcanic zone is homotaxial with a bentonite recognized by Fox and Grant near Chattanooga and in Rhea County, Tennessee, and with one found by Miller and Fuller in the Rose Hill district, Lee County, Virginia, but it is somewhat older than either. The fairly widespread extent of the argillaceous limestones-calcareous claystones of the upper Blackford, and implicitly their contained conodont population, indicates that these synchronous units may be traceable over large areas of southwest Virginia. They are therefore potentially useful as a Olazyan reference time plane in this part of the Appalachians. / Ph. D.