Peralkaline trachytic magma erupted on Terceira, in the Azores are derived from associated basalts by extreme fractional crystallization of an assemblage including amphibole. The eruption of 1761 produced both trachytic and hybrid basaltic lavas and exemplifies magma mixing processes that occurred frequently in the past. Mingling of basaltic magmas produces homogeneous hybrid magmas; mingling between basaltic and trachytic liquids is inhibited by thermal quench of the basaltic magma. Hybridization of benmoreitic magma into basalt may account for its rarity in oceanic island lava suites. / Convection observed in an experimental basalt-pantellerite melt system is not attributable to gravitational instability at the nominally horizontal multicomponent free-diffusion boundary. Stresses due to diffusion in the viscoelastic silicate melts produced a meniscus; inclined density gradients at the meniscus cause convection. / Glassy pumice samples have been leached at ambient conditions, and have lost over 25% of F, Na, K, Si, Fe, Ti and Mn originally present; U, Al, Nb, Ca, Y, Rb and REE show smaller but significant losses.

Upon inundation, the soils in a hydroelectric reservoir are subjected to several years of physical, biological, and chemical changes as the transition from a terrestrial to an aquatic ecosystem is achieved. Changes in Eh, pH, and microbial activity are believed to alter the metal binding capacity of solid substrates (e.g., organic matter, reactive Fe and Mn oxides, and clay minerals) within the soil profile, leading to the remobilization of mercury associated with these phases. / Four cores were collected along a transect from an unflooded forest soil to a pre-impoundment lake bottom sediment in the La Grande-2 (LG-2) Reservoir and watershed. The samples were sequentially extracted to determine the distribution of mercury between three operationally-defined solid compartments: organic carbon (1N NaOH-extractable), reactive Fe and Mn oxides/hydroxides (1N HCl-extractable), and the solid (clay and sulphide) residue. / Results indicate that up to 80% of the mercury in the O-horizon in forest soils and flooded forest soils, and up to 85% of the mercury in lake sediments, is bound to the NaOH-extractable organic carbon fraction. / In the B-horizon of a forest podzol where organic content is low, 40-60% of the total mercury was found to be associated with reactive Fe minerals. In contrast, the flooded soil contains very little reactive Fe at any depth and the associated mercury concentrations are low. I propose that, upon inundation, oxide minerals are reduced and Hg released to the pore waters where it is immediately bound to an available substrate. Analyses of the residues suggest that there is an enrichment of mercury in the residual fraction immediately above the B-horizon of a flooded soil while sulphide mineralization appears to play a role in sequestering mercury in lake sediments.

Fluid-saturated experiments were conducted to investigate the elemental partitioning of boron among melt, aqueous vapor and aqueous liquid (brine) in the system haplogranite-H2O-NaCl at 800°C and 100 MPa. Time series experiments demonstrate that equilibrium was reached in about 90 hours. Runs conducted with low-salinity fluids (0--2 wt. % NaCl) show that boron partitions preferentially into the vapor phase over the haplogranitic melt, whereas results from high-salinity (60--80 wt. % NaCI) experiments suggest that boron has no preference for the brine or the melt. Excluding data from runs that may have been conducted beneath the solvus (2 and 60 wt. % NaCl), the bulk fluidmelt partition coefficients for low-salinity and high-salinity experiments are DB(vapor/melt) = 4.79 +/- 1.52 and DB (brine/melt) = 1.07 +/- 0.34, respectively. Integrating these results yielded DB(vapor/brine) = 4.48 +/- 2.03, suggesting that boron partitions preferentially into the vapor over the brine in a boiling hydrothermal fluid. This may have important implications for mineral exploration, as boron is commonly associated with certain metallic mineral deposits as tourmaline.

Note: Page 8 is plate 1 and not a missing page. / A pattern of alteration has been worked out; and it is hoped that these changes in bulk composition of the wall rock caused by the metasomatic effect of mineralizing fluids can be related to possible mineralogical changes. Care has been taken to describe the local metasomatic changes brought about by the intrusion of igneous rocktypes; as these changes May be confused with those affected by the mineralizing fluids.

The influence of ionic strength (I), magnesium ions and reactive surface area, on calcite crystal growth morphology and surface microtopography were investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Calcite overgrowths were precipitated from aqueous NaCl-NaHCO 3-CaCl2-MgCl2 solutions on reagent grade calcite seed powders and millimeter-size cleavage fragments in a chemo-stat system at 25ºC for up to 6 days. Aliquots of the reacting solutions were sampled regularly for analysis and the suspended seeds were separated for the preparation of Pt-C replicas and TEM imaging. Most cleavage fragments were recovered at the end of the experiments for AFM imaging. / In all experiments, the euhedral {101¯4} rhombohedron of calcite seeds is modified at the same corners and edges within 24 hours of growth. / In the parent solutions seeded with a smaller amount of calcite seed powders and at I = 0.13 m, the crystal morphology of calcite seed overgrowths consists of {101¯4} and a new, prismatic form. The use of a smaller amount of seeds translates into considerably higher precipitation rates per unit surface area and leads to the development of fewer, new morphological growth features.

Thesis (B.Sc.(Hons)) --University of Adelaide, Department of Economic Geology, 1968.

Thesis (M.Sc.) --University of Adelaide, 1957. / Typewritten copy.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1916. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed April 1, 2009)

Thesis (Ph. D.)--University of Chicago. / Reprinted from the Journal of geology, vol. xvii, 1909. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago. / Reprinted from the Journal of geology, vol. xvii, 1909. Includes bibliographical references. Also available on the Internet.