One-atmosphere melting experiments have been performed on two shoshonitic basalts; SO-1 and SO-20; (14 and 9 wt.% MgO, respectively) and an olivine nephelinite HF-13 (11 wt.% MgO), at different oxygen fugacities (NNO+1, NNO, and FMQ), with temperature varying from super-liquidus (1300$ sp circ$C) to near-solidus (1075$ sp circ$C) conditions. The experimental results reveal that iron-oxide crystallization depends strongly on oxygen fugacity, and that their precipitation drives residual liquids towards silica enrichment. Residual liquids obtained from SO-1 and SO-20 reached a maximum of 64 wt.% SiO$ sb2$ for olivine, clinopyroxene, plagioclase and iron-oxide saturated melts at NNO+1, and 59 wt.% SiO$ sb2$ for olivine, clinopyroxene and plagioclase saturated melts at FMQ. The experimental liquids produced from HF-13 reached a maximum of 48 wt.% SiO$ sb2$ at NNO and NNO+1 for iron-oxide, olivine and clinopyroxene saturated melts, however no variation in SiO$ sb2$ concentration was observed for olivine and clinopyroxene-saturated melts at FMQ.

The Sungun porphyry copper deposit is associated with an Andean-type, calc-alkaline diorite/granodiorite to monzonite/quartz-monzonite stock of Miocene age which intruded Eocene volcanosedimentary and Cretaceous carbonate rocks. The intrusive phases are related by fractional crystallization, although surprisingly, the diorite/granodiorite which hosts the mineralization postdates the more evolved quartz monzonite. Copper mineralization was accompanied by both potassic and phyllic alteration. The hydrothermal system involved both magmatic and meteoric waters, and boiled extensively. Molybdenum was concentrated at a very early stage in the evolution of the hydrothermal system and copper later. Early hydrothermal alteration, which was caused by high temperature (340 to >500°C), high salinity ( ~ 60 wt % NaCl equiv.) orthomagmatic fluid, produced a potassic assemblage characterized by addition of K and Cu and depletions in Na, Ca, Mg and Fe in the central part of the stock. Propylitic alteration, which is attributed to a liquid-rich, lower temperature (240--330°C), Ca-rich, evolved meteoric fluid occurred contemporaneously with potassic alteration, but in the peripheral parts of the stock. Phyllic alteration occurred later, at temperatures in the range from 300 to 360°C, overprinting these earlier alterations, and was accompanied by additions of Si (silicification) at the expense of Na, K and Fe and remobilization of Cu from the potassic zone. It resulted from the inflow of oxidized and acidic meteoric waters with decreasing temperature of the system. During potassic alteration, copper solubility is calculated to have been >100,000 ppm, whereas the copper content of the initial fluid responsible for ore deposition was 1200--3800 ppm. This indicates that the fluid was initially undersaturated with respect to chalcopyrite, which agrees with the observation that veins which formed at T > 400°C contain molybdenite but rarely chalcopyrite. Copper solubi

Prior to complete crystallization of leucogranitic magma at East Kemptville, tectonic fracturing induced a pressure drop, allowing a NaCl-HCl-HF-rich fluid phase to separate. This fluid caused pervasive sericitization and extracted the ore metals from the melt. It was then channeled into the fractures and caused greisenization in the apical part of the intrusion. During greisenization, the leucogranite was converted into quartz-sericite greisen through sequential replacement of K-feldspar and albite. Muscovite was replaced by topaz to form quartz-topaz greisen, host to sulphide and cassiterite mineralization. In this greisen, the OH$ sp-$ of muscovite is replaced by H$ sb2$O and O$ sp{2-},$ which leads to its dehydration during microprobe analyses. Close to veins, suphides and cassiterite were re-dissolved in quartz greisen. The altering fluid had a pH of 3.0 and contained 4.8m Cl, 3.7m Na, 0.53m Fe and minor F, K, S and Sn as determined from fluid inclusions and mineral equilibria. The temperature of greisenization was determined to be $480 pm 15 sp circ rm C$ using a F-OH exchange geothermometer between topaz and muscovite and oxygen isotopic data on cassiterite and quartz; the pressure was estimated to be 4.1 $ pm$ 1.0 kbars using fluid inclusion isochores. Alteration occurred though a process of compensated infiltration in which small aliquots of fluid were exchanged between the rock and the vein, while the bulk flow was parallel to the vein. This created a distribution of the components controlled by chemical potential gradients; Fe, Sn, S and F were transported away from the vein and Na towards it. Changes in physicochemical parameters of the fluid were quantified using computer simulation, which, in conjunction with fluid inclusion data, indicates that cassiterite precipitated in response to a pH increase. Changes in a$ sb{ rm Cl-}$ and $f rm O sb2$ were insufficient to account for cassiterite precipitation or acted against it. Modeling further showed that

The early Tertiary marked a period of intense magmatic activity in the Canadian Cordillera as a consequence of tectonic restructuring within the Kula-North American plate system from orthogonal to oblique convergence. Resultant calc-alkaline volcanism formed a discontinuous belt (Challis Arc) along the eastern margin of the Coast Plutonic Complex (CPC) from south-eastern Alaska through Yukon into west-central British Columbia and northern Washington State. The Sifton Range volcanic complex (SRVC) is the Yukon's largest Paleogene erosional remnant of volcanic rocks (240 km2), and represents the only coeval volcanic-plutonic suite within the Sloko-Skukum Group of southern Yukon Territory and northern British Columbia. It comprises a 900-m thick, shallow-dipping, volcanic succession dominated by intermediate to evolved lavas and abundant felsic pyroclastics deposited in a north-westerly trending half-graben. Three volcano-stratigraphic units are documented: (1) Lower Interbedded Unit, (2) Middle lavas, and (3) Upper Interbedded Unit. Locally, the volcanic sequence is intruded by biotite, hornblende, two-feldspar granites of the CPC's Nisling plutonic suite dated at 57.5 Ma. Felsite sills radiate from the main intrusive body, and together with numerous basaltic to dacitic dykes traverse the entire volcanic package. (Abstract shortened by UMI.)

The Itcha Volcanic Complex (IVC) is the easternmost shield of a series of bimodal central volcanic complexes which comprise the Anahim Volcanic Belt (AVB) in central British Columbia. The IVC lavas are distinctly bimodal, with a compositional gap between 52 and 58 wt% SiO$ sb2$ comprising late basaltic and hawaiitic lavas and early felsic lavas of Si-undersaturated to Si-oversaturated character. The hawaiite lavas dominate the late capping stage of the IVC. Their high Sr/Zr ratios indicate that they were derived by crystal fractionation of a clinopyroxene-dominated assemblage at high pressures ($ sim$10 kbar) from parental magmas with compositions similar to the most primitive alkali olivine basalts in the IVC. The majority of later evolved basalts have low Sr/Zr ratios indicating they formed by crystal fractionation at lower pressures. / The similarity of isotopic and the incompatible element ratios suggests that the felsic and mafic magmas of the IVC are co-genetic. The early basal trachytes were derived by an AFC process in crustal magma chambers and appear to have assimilated a significant (15-20%) crustal component. Later, more evolved felsic lavas exhibit a wider range of Si-saturation, which appears to require parental basaltic magmas with a range of silica saturations with less, and more selective, crustal contamination. The compositional gap between the mafic and the felsic lavas of the Itcha shield appears to be related to the difficulty of erupting crystal-rich viscous lavas of intermediate composition. Viscosity models indicate that the rise in viscosity with decreasing Mg is slower at high pressures, which would favour the eruption of lavas of more evolved composition. / Late balsanites have distinct Nb/Zr and isotopic signatures (low $ rm sp{87}Sr/ sp{86}$Sr), requiring a mantle source distinct from that of the alkali olivine basalts.

Copper solubility in water vapor and liquid was measured in the HCl-NaCl-H 2O system at temperatures up to 400°C and vapor-saturated pressure by two series of experiments. The thermodynamic data from these experiments were then applied to model the genesis of volcanogenic massive sulfide deposits and the partitioning of copper between vapor and liquid. / The solubility of copper in liquid was measured in vapor-saturated aqueous HCl/NaCl solutions at temperatures ranging from 40 to 300°C, total chloride concentrations from 0.01 to 1 m, and pH from 0 to 3.5. Copper was found to dissolve primarily as CuCl(aq), CuCl2- and CuCl32-. Data collected from the experiments were regressed to determine the equilibrium constants as functions of temperature (K): Cu(s) + 1/4O2(g) + H+ + xCl- = CuClx1-x +1/2 H2O(l), where x varied from 1 to 3. / Data obtained on the solubility of copper in the liquid phase were used to model gold-copper and gold-zinc mineralization in VMS deposits. Equilibrium path calculations, employing EQ3/6, predict temperatures of precipitation, the paragenetic sequence of minerals, and the chemical composition of chimneys associated with vents on the seafloor at 21°N, East Pacific Rise. The modeling results suggest that the co-precipitation of gold with copper and zinc at different temperatures is determined by the behavior of their complexes in the solution. However, among the models simulated, only the conductive cooling model and combined mixing and cooling model predict the co-precipitation of gold and copper at high temperature (>300°C) and gold-zinc at low temperature (<250°C), which is common in VMS deposits. / The solubility of CuCl(s) in the vapor was measured in a vapor-saturated H2O(I)-H2O(v)-NaCl-HCl (NaCl/HCl; 9:1) system at temperatures ranging from 360 to 400°C, and total chloride concentration from 0.01 to 5 m. At 360°C, the copper solubility can be described by the reaction: CuCl(s) + H2O(v) = CuCl⁺H2O(v), and the equilibrium relationship for this reaction by KC = mCuCl⁺H2Ov /rH2Ov , where mCuCl⁺H2Ov is the molality of copper in the vapor phase and rH2Ov is the density of water vapor; the log KC value is ~-2.01. At 380°C and 400°C, copper solubility is controlled by the reaction: CuCl(s) + 4 H2O(v) = CuCl ⁺ 4H 2O(v). The equilibrium relationship for this reaction is KC = mCuCl⁺4H2O v/r4 H2Ov , and the values of log KC values are 0.22 and 1.17 at 380 and 400°C, respectively. / Partition coefficients for copper between vapor and liquid were calculated for the CuCl-NaCl-HCl-H2O(l)-H2O(v) system at the following conditions, where T = 400°C, P = water vapor saturated pressure, mNaCl = 0.5--2.3m, and mHCl = 0.001 m. The close similiarity of the partition coefficients for copper to those of sodium under the same conditions suggests that partitioning data for NaCl can be used to estimate copper (I) chloride partition coefficients at conditions for which no data are available.

<p> The eastern Willouran Ranges and northern Flinders Ranges, South Australia contain Neoproterozoic and Cambrian outcrop exposures of diapiric breccia contained in salt diapirs, salt sheets and associated growth strata that provide a natural laboratory for testing and refining models of salt-sediment interaction, specifically allochthonous salt initiation and emplacement and halokinetic deformation. Allochthonous salt, which is defined as a sheet-like diapir of mobile evaporite emplaced at younger stratigraphic levels above the autochthonous source, is emplaced due to the interplay between the rate of salt supply to the front of the sheet and the sediment-accumulation rate, and may be flanked by low- to high-angle stratal truncations to halokinetic folds. Halokinetic sequences (HS) are localized (&lt;1000 m) unconformity-bound successions of growth strata adjacent to salt diapirs that form as drape folds due to the interplay between salt rise rate (R) and sediment accumulation rate (A). HS stack to form tabular and tapered composite halokinetic sequences (CHS), which have narrow and broad zones of thinning, respectively. The concepts of CHS formation are derived from outcrops in shallow water to subaerial depositional environments in La Popa Basin, Mexico and the Flinders Ranges, South Australia. Current models for allochthonous salt emplacement, including surficial glacial flow, advance above subsalt shear zones and emplacement along tip thrusts, do not address how salt transitions from steep feeders to low-angle sheets and the model for the formation of halokinetic sequences has yet to be fully applied or tested in a deepwater setting. Thus, this study integrates field data from South Australia with subsurface data from the northern Gulf of Mexico to test the following: (1) current models of allochthonous salt advance and subsalt deformation using structural analysis of stratal truncations adjacent to outcropping salt bodies, with a focus on the transition from steep diapirs to shallow salt sheets in South Australia; and (2) the outcrop-based halokinetic sequence model using seismic and well data from the Auger diapir, located in the deepwater northern Gulf of Mexico. Structural analysis of strata flanking steep diapirs and allochthonous salt in South Australia reveals the transition from steep diapirs to shallowly-dipping salt sheets to be abrupt and involves piston-like breakthrough of roof strata, freeing up salt to flow laterally. Two models explain this transition: 1) salt-top breakout, where salt rise occurs inboard of the salt flank, thereby preserving part of the roof beneath the sheet; and 2) salt-edge breakout, where rise occurs at the edge of the diapir with no roof preservation. Shear zones, fractured or mixed `rubble zones' and thrust imbricates are absent in strata beneath allochthonous salt and adjacent to steep diapirs. Rather, halokinetic drape folds, truncated roof strata and low- and high-angle bedding intersections are among the variety of stratal truncations adjacent to salt bodies in South Australia. Interpretation and analysis of subsurface data around the Auger diapir reveals similar CHS geometries, stacking patterns and ratios of salt rise and sediment accumulation rates, all of which generally corroborate the halokinetic sequence model. The results of this study have important implications for salt-sediment interaction, but are also critical to understanding and predicting combined structural-stratigraphic trap geometry, reservoir prediction and hydrocarbon containment in diapir-flank settings.</p>

<p> Natural manganese oxides are generally formed in surficial environments that are near ambient temperature and water-rich, and may be exposed to wet-dry cycles and a variety of adsorbate species that influence dramatically their level of hydration. Manganese oxide minerals are often poorly crystalline, nanophase, and hydrous. In the near-surface environment they are involved in processes that are important to life, such as water column oxygen cycling, biomineralization, and transport of minerals/nutrients through soils and water. These processes, often involving transformations among manganese oxide polymorphs, are governed by a complex interplay between thermodynamics and kinetics. Manganese oxides are also used in technology as catalysts, and for other applications. </p><p> The major goal of this dissertation is to examine the energetics of bulk and nanophase manganese oxide phases as a function of particle size, composition, and surface hydration. Careful synthesis and characterization of manganese oxide phases with different surface areas provided samples for the study of enthalpies of formation by high temperature oxide melt solution calorimetry and of the energetics of water adsorption on their surfaces. These data provide a quantitative picture of phase stability and how it changes at the nanoscale. </p><p> The surface energy of the hydrous surface of Mn₃O₄ is 0.96 &plusmn; 0.08 J/m², of Mn₂O₃ is 1.29 &plusmn; 0.10 J/m², and of MnO₂ is 1.64 &plusmn; 0.10 J/m². The surface energy of the anhydrous surface of Mn₃O₄ is 1.62 &plusmn; 0.08 J/m², of Mn₂O₃ is 1.77 &plusmn; 0.10 J/m², and of MnO₂ is 2.05 &plusmn; 0.10 J/m². Supporting preliminary findings (Navrotsky et al., 2010), the spinel phase (Mn₃O₄) has a lower surface energy (more stabilizing) than bixbyite, while the latter has a smaller surface energy than pyrolusite. These differences significantly change the positions in oxygen fugacity&mdash;temperature space of the redox couples Mn₃O₄-Mn₂O₃ and Mn₂O₃-MnO₂ favoring the lower surface enthalpy phase (the spinel Mn₃O₄) for smaller particle size and in the presence of surface hydration. </p><p> Chemisorption of water onto anhydrous nanophase Mn₂O₃ surfaces promotes rapidly reversible redox phase changes at room temperature as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Water adsorption microcalorimetry (in situ) at room temperature measured the strongly exothermic integral enthalpy of water adsorption (-103.5 kJ/mol) and monitored the energetics of the redox phase transformation. Hydration-driven redox transformation of anhydrous nanophase Mn(III)₂O₃, (high surface enthalpy of anhydrous surfaces 1.77 &plusmn; 0.10 J/m²) to Mn(II,III)₃O₄ (lower surface enthalpy 0.96 &plusmn; 0.08 J/m²) occurred during the first few doses of water vapor. Surface reduction of nanoparticle bixbyite (Mn₂O₃) to hausmannite (Mn₃O₄) occurs under conditions where no such reactions are seen or expected on grounds of bulk thermodynamics in coarse-grained materials. </p><p> Layered structure manganese oxides contain alkali or alkaline earth cations and water, are generally fine-grained, and have considerable thermodynamic stability. The surface enthalpies (SE) of layered and tunnel structure complex manganese oxides are significantly lower than those of the binary manganese oxide phases. The SE for hydrous surfaces and overall manganese average oxidation state (AOS) (value in parentheses) are: cryptomelane 0.77 &plusmn; 0.10 J/m² (3.78), sodium birnessite 0.69 &plusmn; 0.13 J/m² (3.56), potassium birnessite 0.55 &plusmn; 0.11 J/m² (3.52), and calcium birnessite 0.41 &plusmn; 0.11 J/m² (3.50). Surface enthalpies of hydrous surfaces of the calcium manganese oxide nanosheets are: &delta;Ca_0.39MnO_2.3nH₂O 0.75 &plusmn; 0.10 J/m² (3.89) and &delta;Ca_0.43MnO_2.3nH₂O 0.57 &plusmn; 0.12 J/m² (3.68). The surface enthalpy of the complex manganese oxides appears to decrease with decreasing manganese average oxidation state, that is, with greater mixed valence manganese (Mn^3+/4+). Low surface energy suggests loose binding of H₂O on the internal and external surfaces and may be critical to catalysis in both natural and technological settings.</p>

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