979 resultados para Castro Valley


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Presently non-commercial occurrences of Mississippi Valley-type ore assemblages in the Middle Silurian strata of the Niagara Peninsula have been studied. Based on this detailed study, a new poly-stage genetic model is proposed which relates ore mineralization in carbonate environments to the evolution of the sedimentary basin. Sulphide ore mineralization occurred during two episodes: 1. During the late diagenesis stage, which is characterized by compaction-maturation of the sediments, the initial mineralization took place by upward and outward movement of connate waters. Metals were probably supplied from all the sediments regardless of their specific lithologies. However, clay minerals were possibly the main contributors. The possible source of sulphur was from petroleum-type hydrocarbons presently mixed with the sediments at the site of ore deposition. Evidence for this is the fact that the greatest abundance of ore minerals is in petroliferous carbonates. The hydrocarbons probably represent liquids remaining after upward migration to the overlying Guelph-Salina reservoirs. The majority of sphalerite and galena formed during this period, as well as accessory pyrite, marcasite, chalcopyrite, chalcocite, arsenopyrite, and pyrrhotite; and secondary dolomite, calcite, celestite, and gypsum. 2. During the presently ongoing surface erosion and weathering phase, which is marked by the downward movement of groundwater, preexisting sulphides were probably remobilized, and trace amounts of lead and zinc were leached from the host material, by groundwaters. Metal sulphides precipitated at, or below, the water table, or where atmospheric oxygen could raise the Eh of groundwaters to the point where soluble metal complexes are unstable and native sulphur co-precipitates with sphalerite and galena. This process, which can be observed today, also results in the transport and deposition of the host rock material. Breakdown of pre-existing sulphide and sulphate, as well as hydrocarbon present in the host rock, provided sulphur necessary for sulphide precipitation. The galena and sphalerite are accompanied by dolomite, calcite, gypsum, anglesite, native sulphur and possibly zincite.

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This qualitative case study identifies and discusses the standards and risk management practices of the Ottawa Valley whitewater rafting industry and the impacts of the government enforced Special-purpose Vessels Regulations are discussed. Data collection occurred using a single case study design, which included interviews and document analysis. This study found that internal, industry, and actual standards are influenced through a variety of sources. These standards were found to affect the risk management practices of commercial whitewater rafting providers. In general, these standards promoted a high level of risk management within the Ottawa Valley rafting industry. The Special-purpose Vessels Regulations were found to be non-influential in raising the risk management standards of the Ottawa Valley whitewater rafting industry.

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Certificate for 1 share of capital stock in Nicola Valley Coal and Coke Company to Welland D. Woodruff, May 13, 1905.

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Certificate for 21 shares of capital stock in Nicola Valley Coal and Coke Company to Welland D. Woodruff, Oct. 16, 1905.

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Tesis (Maestría en Enfermería, con especialidad en Administración de Servicios de Enfermería) U.A.N.L.

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Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

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Tesis (Maestría en Administración con Especialidad en Mercadotecnia) U.A.N.L.