The Tatric crystalline unit of the Western Carpathians in northern Slovakia displays an inverted metamorphic sequence where high-grade migmatite and orthogneiss units are overlying lower-grade mica schists. Enclosed within the migmatites are lenses of eclogite-bearing amphibolites. Conventional geothermobarometry coupled with isochemical modeling constrained P-T paths that exhibit contrasting metamorphic histories for rock units that are now heterogeneously interleaved. Relict eclogite facies assemblages with occasionally preserved omphacite record post-peak pressure conditions of 1.7-1.8 GPa followed by near isothermal decompression at ∼750°C leading to intensive re-equilibration of eclogites at high-pressure granulite facies conditions and development of diopside + plagioclase symplectitic textures. New ID-TIMS Sm-Nd dating of garnet separated from the omphacite-bearing eclogite yields a whole rock-garnet isochron age of 337 +/- 10 Ma, with an epsilon Nd isotopic composition of +8.3. While major element profiles across the garnets display little variation, the trace element distribution shows a typical HREE enrichment profile and a slight core to rim disparity with LREE and MREE concentrations higher in the cores and higher HREE in the rims. Granulite-facies migmatites that host the eclogite boudins record lower pressure metamorphic conditions of 1.2 GPa at ∼750°C and a similar retrograde path. The lower-grade micaschists reached metamorphic conditions of 0.8 GPa at ∼650°C. Monazite U-Pb analysis from a migmatite surrounding the eclogite boudins yields one population of ca. 380 Ma age. Another migmatite away from the eclogite yields two populations monazite ages. A robust 340 +/- 11 Ma monazite U-Pb age is indistinguishable from our garnet age and U-Pb SIMS age of zircons in the anatectic leucosome of the migmatite (347 +/- 7 Ma). We interpret the ca. 340 Ma ages to represent the exhumation of the deep crustal root of the Variscan orogen into the middle crust coeval with anatexis. A younger monazite U-Pb age of 300 +/- 16 Ma is consistent with 40Ar/39Ar thermochronology data of ca. 310 Ma that is likely indicative of the Late Carboniferous I-type magmatism and cooling in the Tatric block. Cooling rates calculated by garnet diffusion modeling yield estimates of ∼30 °/Ma. This exhumation was likely tectonically forced by the action of a rigid indentor which prompted the weak lower crust to be heterogeneously extruded to mid-crustal levels at a time coeval with anatexis and subsequently extruded with mid-crustal material to the upper crust.

Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganeite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mossbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganeite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Neel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group's potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles' reactivity in the environment.

The interactions of polysaccharides (dextrin, amylopectin and carboxymethyl cellulose (CMC)) with variously modified quartz samples were investigated using floatability, wettability, electrokinetic and adsorption tests, supplemented by conventional titration and infrared spectroscopic studies. The quartz samples were treated either by methylation (rendered hydrophobic), lead coating (introduction of metallic adsorption centres), or both forms of surface modification. The presence of metal ionic sites on a quartz surface played a decisive role in polysaccharide adsorption. The adsorption densities of both dextrin and CMC on lead-coated quartz were both much higher and much more pH-dependent than those on uncoated quartz. The "hydrophobic bonding" of dextrin with mineral surfaces as reported in the literature was not observed with hydrophobic (methylated) quartz. However, if the quartz contained surface lead ionic sites and was also methylated, it adsorbed more dextrin than unmethylated, lead-coated quartz. This was also true for the adsorption of CMC onto similarly modified quartz samples. To obtain a rational understanding of the importance of metal ions in polysaccharide adsorption, studies of the solution chemistry of polysaccharides and metal ions were conducted. CMC co-precipitated with both metal cations and metal hydroxy complexes, (including metal hydroxides), whereas dextrin co-precipitated only with metal hydroxides. Co-precipitation involving either polysaccharide caused a decrease in the solution pH. Dextrin-metal co-precipitation occurred at pH optima of 7.5, 8, 9, 11, and 12 for ferric, aluminum, cupric, lead and magnesium ions, respectively. Infrared spectroscopic studies of the precipitates revealed the elimination of glucose ring deformation, suggesting a chemical basis for the interaction between dextrin and metal hydroxides. The surfaces of sulphide minerals behaved like hydroxide during dextrin adsorption. Since copper and lead hydroxides form over different pH ranges, the pH ranges for optimum adsorption of dextrin on copper sulphides and lead sulphides were different. The results of preliminary flotation tests indicated that dextrin could be utilized in the differential flotation of Cu-Pb sulphides. Small scale flotation tests conducted on synthetic mixtures of chalcopyrite and galena confirmed this point. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

The 85-m Brushy Basin Member of the Morrison Formation in western Colorado comprises a 30-m lower division mostly made of red-brown mudstone and a 55-m upper division characterized by variegated smectitic mudstones. River-channel sandstones embedded in the floodplain mudstones tend to have cut down to resistant caliche paleosols. Also present are thin beds of lacustrine micritic limestone and altered silicic ashfalls. These strata were studied at three locations, from west to east: Trail Through Time (TT), Fruita Paleontological Resource Area (FP), and Echo Canyon (EC). Morrison strata developed in a back-bulge depozone of a foreland basin system, with the debris eroded from thrust slices to the west. The Morrison strata differ from many foreland basins because the Morrison-age forebulge deposits west of the preserved basin were eroded due to plateau uplift of eastern Nevada and western Utah. Petrographic modal analyses of 87 sandstones date a major pulse of the Nevadan Orogeny at the transition from the Salt Wash Member to the Brushy Basin Member in late Kimmeridgian time. Brushy Basin sandstones show significant increases upsection in plagioclase, total lithic fragments, and especially volcanic fragments. Abundant volcanic ash accumulated on the floodplains. The source areas for the Morrison Formation were the Ellko and Mogollon Highlands with feldspathic litharenite sands characterized by relatively high proportions of lithic and volcanic fragments and plagioclase. Floodplain red-brown mudstones are highly smectitic with abundant smectite altered from silicic volcanic ash, in both the lower and the upper divisions. Depositional facies and architectural element analysis show that the rivers were low gradient, mainly anastomosing, with perennial flow and seasonal peaks in discharge. Dinosaur bone accumulations are found in some floodplain ponds. Isolated bones are present in anastomosing sandstones at the Trail Through Time. At Fruita Paleontological Resource Area, major acummulations of bones were rapidly buried in the deep pools at three bends in a meandering river.

The iron-nickel alloy phase transformations and metal-silicate reactions that occurred in relatively unshocked, types 4–6 ordinary chondrites were investigated using several approaches. Laboratory cooling experiments were used to study kamacite nucleation and growth during cooling. When polycrystalline taenite cools to temperatures of kamacite stability, kamacite allotriomorphs form at the taenite grain boundaries. If the taenite is phosphorus-saturated, intragranular (Widmanstatten) kamacite needles will form after small amounts of undercooling. However, phosphorus-free alloys will undercool more than 200°C without forming intragranular kamacite precipitates. A monocrystalline, phosphorus-free taenite particle will remain homogeneous as it cools through the taenite + kamacite field and will transform to martensite without a composition change. Metallographic techniques were used to study the microstructures and phase compositions of metal particles in relatively unshocked ordinary chondrites. Chondritic metal particles had widely varying bulk compositions after chondrite aggregation, but experienced intergrain homogenization and taenite grain growth during prograde and peak temperature metamorphism. Taenite grain growth was extensive in types 5 and 6 ordinary chondrites, resulting in many monocrystalline taenite particles. The phase transformations that occurred during cooling depended on whether taenite (phosphorus-poor) was polycrystalline or monocrystalline. Polycrystalline taenite particles experienced small amounts of undercooling within the taenite + kamacite field and transformed to “zoned taenite + kamacite particles” by the diffusion-controlled reaction, taenite → taenite + kamacite. Monocrystalline taenite particles experienced more than 200°C of undercooling; they remained homogeneous and metastable (iron-supersaturated) during cooling. The monocrystalline taenite particles cooled below the martensite-start temperature, and transformed to “zoneless plessite particles” by the taenite → martensite → tetrataenite + kamacite reaction. The occurrence of zoned taenite + kamacite particles and zoneless plessite particles within the same ordinary chondrite is compatible with cold accretion followed by prograde and retrograde metamorphism. The importance of metal-silicate reactions in ordinary chondrites was investigated by analyzing olivine crystals near olivine-metal interfaces. Olivine fayalite concentrations decrease by approximately 2 mole % near zoned taenite + kamacite particles, and increase by approximately 2 mole % near zoneless plessite particles. Chemical thermodynamic modeling shows that silicate-metal reactions occurred during slow cooling due to variable amounts of taenite undercooling.

This study uses ceramic petrography to understand the meaning of “Iroquoian” ceramic traits in eastern New York and southern New England. This analysis assumes that style represents nonverbal behavior residing in both decorative and technologic attributes. Style manifests itself as symbolic, iconographic, and technologic communication that can be active or passive. Technologic style is learned behavior that is slow changing, and represented as variation in manufacturing attributes. Because of the enculturative nature of technologic style, it is possible to distinguish social phenomena, especially group affiliation, using ceramic petrography Ceramic petrography works without resort to typological analysis. Previous attempts to address this question using the typological method have been confounded by the great variability in northeastern ceramic traits. My approach combines optical mineralogy with macroscopic examination to study 91 vessel lots from Mohawk, Hudson, Housatonic and Connecticut river valley sites of Terminal Woodland age. I test hypotheses about northeastern group affiliation expressed in technologic terms. I find that: (1) the mineral composition of aplastic paste inclusions differentiates the ceramics of each river drainage; (2) analysis of construction techniques shows that Mohawk River Valley ceramics were drawn, while those to the east were coil-built; (3) surface treatment and collar design application techniques also show distinctions between central Mohawk River Valley ceramics and those of eastern New York and southern New England; (4) the use of slips has a clinal distribution from 76% in the Mohawk River Valley sample to 12% in the Connecticut River Valley sample. Clearly, pan-northeastern decorative traits were incorporated and combined into locally distinct stylistic repertoires. This study shows that “Iroquoian” traits in southern New England ceramics were of local Algonquian manufacture. Traditional arguments relying upon unilateral diffusion and trade from central New York do not explain ceramic diversity in southern New England. Northeastern archaeologists need to develop a model based upon multidirectional flow of traits integrated with a realistic theory of style and stylistic change. This study shows clear distinctions between the ceramics of two culturally and linguistically distinct northeastern peoples, who interacted in an open and fluid system that allowed association and mixture of people and ideas.

The main Karoo Basin of South Africa contains a relatively continuous sequence of continental deposits that accumulated over a 100 million year period from Permo-Carboniferous (280 Ma) to early Jurassic (180 Ma). In the southwestern region of the basin the Karoo succession is approximately 4 000 m thick, the upper half of which consists of vertebrate fossil-bearing fluvial rocks of the Beaufort Group. This study deals with Lower Beaufort (Adelaide Subgroup) strata belonging to the Teekloof Formation which are exposed in the cast-west trending erosional escarpment between the towns of Beaufort West and Fraserburg in the central Cape Province. The 450-mctre succession consists mainly of vertically accreted floodplain mudrocks with interbedded continuous sheets of fine-grained sandstone that bear evidence of having accumulated by lateral accretion on the inner banks of meandering channels. The mudrocks contain numerous fossilized skeletons of therapsid "mammal-like" reptiles as well as more primitive cotylosaurs and a few amphibians. Rarely, impressions of Glossopteris leaves and equisetalcan stems are found although root moulds are relatively abundant. Several types of calcareous nodules and sheets occur in the mudrocks and arc interpreted as evidence of calcic palaeosols that formed under semi-arid climatic conditions. This is an interdisciplinary study that integrates a conventional sedimentary facies analysis with investigations of the taphonomy of in situ therapsid fossils and the nature and distribution of palaeosols. Such an approach has not previously been applied to any of the Karoo strata. The results contain descriptive and quantitative information on sedimentary processes, palaeohydrology, absolute time represented in the stratigraphic record and the topography, soils and habitats of the ancient landscape. These are summarized into a palaeoenvironmental synthesis of the Teckloof Formation.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering, Johannesburg, 2018 / MT 2019

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