MESMEG / Department of Mining and Environmental Geology / Muyexe magnesite deposit is situated in the Giyani Greenstone Belt in South Africa. Despite mining activities currently taking place at Muyexe magnesite deposit, little information is available about the geology and geochemistry of the deposit. This has resulted in a gap of information about the nature and character of magnesite, namely; its geology, mineralogy, geochemistry and mode of occurrence. Consequently, there is a need for further investigation of the magnesite deposit. The main objective of the study was to establish the geology and geochemistry of the Muyexe magnesite deposit and to ascertain its mode of occurrence. Further work involved undertaking detailed geological mapping, magnesite and rock sampling for petrographic and geochemical studies using petrographic microscopy and X-ray fluorescence spectrometry and identification of minerals in rocks and magnesite through X-ray diffractometry. A total of 20 magnesite and 4 host rock samples were collected from the Muyexe magnesite deposit. Furthermore, 62 rock samples were collected during geological field mapping of which 16 representative samples were selected for further analysis. X-ray fluorescence spectrometry was conducted on all selected samples of magnesite and rocks. XRD analysis was conducted on 12 rocks and 2 magnesite samples. Mineralogy of the rocks was also confirmed using petrographic microscopy. Detailed geological map of the Muyexe area revealed that the area is dominated by metamorphic ultramafic and mafic rocks. Basalt and peridotite are intrusions within the rock. The serpentinites and peridotites were found to be the source rock for magnesite mineralization, while the peridotite is the source rock for serpentinites rocks. XRD analysis revealed that magnesite in the Muyexe magnesite deposit is associated with silica and dolomite, while XRF data revealed that the following major oxides are present in magnesite as impurities; silicon dioxide (SiO2), calcium oxide (CaO), and iron oxide (Fe2O3). These oxides reduce the quality of magnesite, thus, their removal is necessary during processing. Magnesite of this deposit was found to be of good quality, with an average value of 54.02 wt. %. Magnesite at Muyexe was formed due to precipitation of Mg2+ along the fractures of serpentinites and peridotites due to CO2rich hydrothermal fluids. Magnesite occurs as a cryptocrystalline of the Kraubathtype. / NRF

This study describes the use of Landsat MSS and TM for geological applications in two Scottish areas: Lochindorb and Loch Tuel; and one Malaysian area: Kedah-Perak. The areas are poorly exposed and highly vegetated. The data were digitally processed with the objective of producing more interpretable images. The processes include contrast enhancement, ratioing, subtraction, principal component analysis, discriminant analysis, filtering, the combination of images as colour composites, and producing negative images of the data. Geological interpretation of the most informative images was undertaken by visual interpretation. In the Lochindorb area, Landsat MSS imagery did not prove useful for superficial deposits mapping, and the resolution offers by the TM is still not sufficient for semi-detailed mapping at scale 1: 50,000. The combination of TM imagery and aerial photographs, however, made the mapping task easier and produced "better" map. In the Kedah-Perak area, textural information is more important than spectral information for lithological interpretation and many image units correlate well with major mapped rocks. Lineaments are well expressed on Landsat imagery and are mapped for the Loch Tummel and Kedäh-Perak areas. The lineament maps for both areas confirm many mapped faults and reveal a new prominent lineaments (probably faults). For the Loch Tummel area, the relative merits of TM versus MSS data were examined. Both produced similar results regarding major lineament orientations, but the TM provides a good improvement over the MSS in the ability to map lineaments. For both areas, lineaments appear to be correlated with geomorphology (lithology), and with the occurrence of ore deposits and probably geologic structure for the Kedah-Perak area. Landsat imagery can be used to aid lithological mapping in Malaysia, but has not proved useful for Scotland (U. K. ) because of different objectives and constraints. However, Landsat imagery is an effective tool in mapping lineaments for both areas.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 14, 2010) Includes bibliographical references (p. 99-104)

The Guerrero terrane of western Mexico is characterized by an Upper Jurassic-Lower Cretaceous volcanic-sedimentary sequence of arc affinity. The arc assemblage rests unconformably on partially metamorphosed rocks of possible Triassic-Jurassic age. These "basement units," the Arteaga and Placeres Complexes and the Zacatecas Formation, are composed of deformed turbidites, basalts, volcanic-derived graywackes, and blocks of chert and limestone. Sandstones from the basement units are mostly quartzitic and have a recycled orogen-subduction complex provenance. They have negative ᵋNdi (-5 to -7), model Nd ages of 1.3 Ga., and enrichment in light REE, indicating that they were supplied from an evolved continental crust. The volcanic graywackes are derived from juvenile sources (depleted in LREE and ᵋNd = +6), though they represent a small volume of sediments. Primary sources for these turbidites might be the Grenville belt or NW South America. Basement rocks in western North America are not suitable sources because they are more isotopically evolved. Igneous rocks from the basement units are of MORB affinity (depleted LREE and ᵋNdi = +10 to +6). The Jurassic(?)-Cretaceous arc volcanic rocks have ᵋNdi (+7.9 to +3.9) and REE patterns similar to those of evolved intraoceanic island arcs. Sandstones related to the arc assemblage are predominantly volcaniclastic. These sediments have positive ᵋNdi values (+3 to +6) and REE with IAV-affinity. The Guerrero terrane seems to be characterized by two major tectonic assemblages. The Triassic-Middle Jurassic "basement assemblage" that corresponds to an ocean-floor assemblage with sediments derived from continental sources, and the Late Jurassic-Cretaceous arc assemblage formed in an oceanic island arc setting. During the Laramide orogeny the arc was placed against nuclear Mexico. Then, the polarity of the sedimentation changed from westward to eastward, and sediments derived from the arc-assemblage flooded nuclear Mexico. This process marks the "continentalization" of the Guerrero terrane, which on average represents a large addition of juvenile crust to the western North American Cordillera during Mesozoic time.

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (February 17, 2010) Includes bibliographical references (p. 63-67)

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Geology and Geophysics, 2005? / "December 2004" Bibliography: p. 330-369. Also available electronically.

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Geology and Geophysics, 2005? / Title from cover of source document (viewed July 22, 2005). "December 2004" Bibliography: p. 330-369 of source document. Also available in print version.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vii, 117 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes bibliographical references.