>Magister Scientiae - MSc / The paucity of geochemical criteria for stratigraphic correlations and defining the styles of mineralisation pose serious problems in locating PGE-rich zones in the Platreef. This study is therefore aimed at identifying and appraising process-based mineralogical/geochemical criteria which may be useful in stratigraphic correlations and characterizing the nature and styles of PGE mineralisation. In addition, the work investigated the possible use of geochemical vectoring as a tool to locate the PGE-rich zones. Boreholes OY 482 and SS 330, drilled at the Overysel and Sandsloot farms respectively, were logged, and a total of 119 quarter cores were sampled for petrographic studies. The elemental contents in the rocks were determined by XRF and ICP-OES analyses and were evaluated using various statistical and mass balance techniques. In borehole OY 482, where the floor rock is Archaean granite, the Platreef consists of three feldspathic pyroxenite sills referred to as Lower, Middle and Upper Platreef units, from the bottom to the top, respectively. The results show that the Lower and Upper Platreef units have higher median values of Mg# (0.58 and 0.57) and Ni/Cu (0.68 and 0.75) when compared to the Middle Platreef (Mg#: 0.54 and Ni/Cu: 0.67) which may not be totally suggestive of two magmatic intrusive pulses. In borehole SS 330, where the floor rock is dolomite, the rocks consist of clinopyroxenites and olivine clinopyroxenites (variably serpentinised). These two units are intercalated with each other and are products resulting from the injection of Platreef magma sills within the dolomite floor rock. The hierarchical clustering and mass balance calculations show that when compared to the Platreef feldspathic pyroxenites, which have higher SiO2, Al2O3 and Fe2O3 median contents, the clinopyroxenites possess higher CaO median content whereas the olivine clinopyroxenites have higher MgO and LOI median contents. The PGE-rich zones (i.e. Pt+Pd) in clinopyroxenites are marked by low Ca/Mg median values, whereas in both, the olivine clinopyroxenites and the Platreef units, these zones are marked by high Mg/Fe median values. The suggested base metal index [(Cu/Zn) x (Ni/Co)] used to vector towards PGE-rich zones, which reflects the presence of the base metal sulphides (BMS), correlates with the Pt+Pd in the BMS-rich zones. This is not always the case in zones of low BMS contents which may reflect changes in the mineralogy of the BMS. In conclusion, the two boreholes studied show contrasting petrographic and geochemical attributes. This dissimilarity is mainly due to the fact that borehole OY 482 comprises Platreef magmatic rocks whereas borehole SS 330 intersected metamorphic/ metasomatic rocks.

Ochre is a culturally significant material that is commonly recovered from archaeological sites. However, despite its ubiquity it has yet to realize its full interpretive potential as an artifact of archaeological inquiry, specifically in the context of geochemical characterization studies. Studies of this type, often referred to as ‘sourcing’ studies, involve the application of techniques in radiation physics to determine the elemental composition of artifacts and raw materials. These data are then used interpret patterns of behaviour in the procurement, movement, and trade of different artifact classes such as obsidian, chert, or ceramic. By comparison, geochemical characterization studies centred on ochre-related activities are fewer in number. This thesis consists of three case studies that developed methodological foundations for the geochemical study of ochre in regions of British Columbia and Ontario, Canada, respectively. Using instrumental neutron activation analysis and X-ray fluorescence, ochre from geologic outcrops and archaeological sites were analysed to determine their elemental composition. Multivariate statistical tests, including principal components and canonical discriminant analyses, were conducted to explore patterns and variability in ochre geochemistries. The results described in the following papers demonstrate the challenges and limitations for characterization studies of ochre, and present considerations for expanded research in these geographic regions. This thesis offers contributions to broader topics of discussion in archaeological sciences, such as the accurate and precise acquisition of geochemical data, the role of geologic scales and diagenetic processes on the chemistries of iron oxides, how to identify and interpret patterns in elemental data sets, and the utility and limitations of portable analytical technologies. This research has established important methodological foundations for the study of ochre in British Columbia and Ontario, and has demonstrated the potential for expanded analysis of materials from additional archaeological sites and geologic outcrops. This will enable the future interpretation and regional synthesis of patterns and networks of ochre-related activities, including quarrying and procurement, trade and exchange, and variability in use contexts. / Dissertation / Doctor of Philosophy (PhD)

The use of geochemical analysis for characterization studies of archaeological material has been increasing for decades. In recent years, advancements in X-ray fluorescence (XRF) instrumentation have led to hand-held portable XRF (pXRF) instruments capable of on-site, rapid, non-destructive analysis. The addition of pXRF to the archaeologist's toolkit has the potential to revolutionize geochemical characterization studies as research design can be informed by field analysis, once off-limits museum collections may now be analyzable, and data can be gathered on in-situ objects without disturbing their context. This new instrumentation has shown promise in characterization studies on a variety of archaeological materials, including ceramics. Particularly, it has been shown to generate data useful in distinguishing the geochemical provenance of artifacts. While most existing provenance studies that employ pXRF involve obsidian, it is possible that pXRF is a suitable analytical tool for ceramics as well, since instrumental neutron activation analysis (INAA) and laboratory XRF have both been used in provenance studies of obsidian and ceramics. This thesis reports research that utilized a Bruker hand held pXRF analyzer to study ceramics and plaster floors from Classic Period (ca. AD 250-1000) archaeological sites in southeast Mesoamerica. The data gathered from this analysis are used to examine the ability of pXRF to address archaeological questions of archaeological provenance on ceramic material and human activity patterns on archaeological plaster. The data gathered on ceramic material is analyzed to determine if "valley profiles" (or "chemical fingerprints") can be created for samples excavated in the same valley and to investigate inter-valley trade. Data from the plaster samples is examined to determine if pXRF can detect human activity patterns on plaster floors and, if so, if the activity is identifiable. The results suggest that, while pXRF results can be used to create "valley profiles" for provenance research, it is difficult to ascertain if it can be used to identify items of trade. This investigation also shows that, while pXRF data can identify human activity on plaster, it is difficult to determine what those activities were. This leads to the conclusion that pXRF has potential for both provenance and prospection studies on earthen materials. However, methodological development is necessary to fine tune research design. This thesis contributes to a greater understanding of the potentials and limitations of pXRF instrumentation in characterization studies of archaeological materials as well as understanding cultural-historical details in Classic southeast Mesoamerica.

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Made available in DSpace on 2014-12-17T15:42:06Z (GMT). No. of bitstreams: 1 JoaoBAF_DISSERT.pdf: 2926590 bytes, checksum: 284a772c6dacfa2a7184d7f4569c6cab (MD5) Previous issue date: 2011-03-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Although there are many studies on urban dust contamination by heavy metals in developed countries, little attention has been paid to this type of study in developing countries, including Brazil. Therefore, a series of investigations were performed to provide signatures of heavy metals in urban dust and assess the potential sources in the city of Natal - RN-Brazil. The fraction of these sediments was studied to pass through a sieve of 63 micrometers. For the study analyzed two groups of samples, one collected in September 2009 at the end of the rainy season (9 samples) and one collected in January 2010 in the dry season (21 samples). So in all, thirty sediment samples were collected from the street. Then, in Fluorescence Spectrometry X-rays were determined major elements SiO2, Na2O, K2O, Al2O3, MgO, P2O5, Fe2O3, MnO, TiO2 and CaO, and trace Rb, Cr, Ni, Cu, Zn, Sr and Pb by an ICPOES was determined Zn, V, Na, K, Ni, Mn, Mg, P, Fe, Cr, Cu, Pb, Ba, Ca and Al from leaching HCl 0.5 mol L-1 . The results of the concentrations of elements show that the greater presence of these occurs in the dry season, except for Si which is higher in the rainy season. Analyses by geoaccumulation Index (IGEO) Enrichment Factor (EF), Contamination Factor (CF), analysis correlation and Hierarchical Cluster, confirm that Zn, Cu and Pb is anthropogenic character. Zinc may be derived from various sources related to motor vehicles or the road signs and street grids. The elements Na, K, Mg and Ca may be related to droplets suspended in air containing cations and anions present in seawater (salty), common in Christmas throughout the year, brought by winds SE-NW. The elements Na, Mg, Ca and K are the most abundant in seawater and were analyzed in this study. This indicates that the source of these additional elements detected by analyzing the contamination factor may be the very sea. Moreover, Ni, Fe, Cr and Ba can be either as a source of anthropogenic geog?nica. The source of Ca is different, because it comes in lime and paint (painting guides of buildings and streets) in construction materials, but may also be present in sediments in the fragments of shells or carbonate bioclasts common in the coastal area / Embora existam muitos estudos sobre a contamina??o de poeiras urbanas por metais pesados nos pa?ses desenvolvidos, pouca aten??o tem sido dada a este tipo de estudo nos pa?ses em desenvolvimento, incluindo o Brasil. Portanto, uma s?rie de investiga??es foram realizadas para fornecer assinaturas de metais pesados em poeiras urbanas e avaliar as fontes potenciais na cidade do Natal RN-Brasil. A fra??o estudada destes sedimentos foi a passante na peneira de 63 μm. Para o estudo foram analisados dois grupos de amostras, sendo um coletado no m?s de setembro de 2009 no final da esta??o chuvosa (9 amostras) e outro coletado no m?s de janeiro de 2010 no final da esta??o seca (21 amostras). Portanto ao todo, trinta amostras de sedimentos de rua foram coletadas. Em seguida, por Espectrometria de Fluoresc?ncia de raios X foram determinados os elementos maiores SiO2, Na2O, K2O, Al2O3, MgO, P2O5, Fe2O3, MnO, TiO2 e CaO e tra?os Rb, Cr, Ni, Cu, Zn, Sr e Pb. Pela t?cnica de ICP-OES foram determinados Zn, V, Na, K, Ni, Mn, Mg, P, Fe, Cr, Cu, Pb, Ca, Ba e Al a partir de lixivia??o a HCl 0,5 mol L-1. Os resultados das concentra??es dos elementos mostram que a maior presen?a desses ocorre na esta??o seca, com exce??o para o Si que ? maior na esta??o chuvosa. As an?lises por ?ndice de Geoacumula??o (IGeo), Fator de Enriquecimento (FE), Fator de Contamina??o (FC), an?lises de correla??o e agrupamentos, confirmam que Zn, Cu e Pb tem car?ter antropog?nico. O Zn pode ser proveniente de fontes diversas relacionados aos ve?culos automotores ou ?s placas de sinaliza??o e grades das ruas. Os elementos Na, K, Mg e Ca podem estar relacionados ?s got?culas de ar que cont?m em suspens?o os c?tions e ?nions presentes na ?gua do mar (maresia), comum em Natal durante todo o ano, trazida pelos ventos SE-NW. Os elementos Na, Mg, Ca e K s?o os mais abundantes na ?gua do mar e foram analisados no presente trabalho. Isto indica que a fonte adicional destes elementos detectada atrav?s da an?lise do fator de contamina??o pode ser a pr?pria maresia. Por outro lado, Ni, Fe, Cr e Ba podem ser tanto de origem antropog?nica como de origem geog?nica. A fonte do Ca ? diversa, pois este entra na cal e tintas (pintura de edifica??es e guias de ruas), nos materiais de constru??o civil, mas pode estar tamb?m presente nos sedimentos nos fragmentos de conchas ou bioclastos carbon?ticos comuns na ?rea litor?nea