Гидротермальное платиновое оруденение месторождения Ватерберг (Трансвааль, республика Южная Африка)статья
Статья опубликована в журнале из списка RSCI Web of Science
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Дата последнего поиска статьи во внешних источниках: 23 августа 2019 г.
Аннотация:The ore mineral assemblages in the Waterberg deposit (South Africa) is represented by a rare association of quartz with platinum minerals, which originated under the condition of hydrothermal metasomatism by the deposition of ore material in the open space from circulating hydrothermal fluids. The deposit is located within the metallogenic field of the Bushveld Complex and confined to zones of brecciated and metasomatically silicified felsites in the roof of the Bushveld Pluton. Additionally to quartz, the ore also contains hematite and the following accessory minerals: monazite, lopezite, chromatite, roscoelite, and muscovite. The platinum-group elements (PGE) are unevenly distributed over the silicified ore zone. Their contents vary from a few to 1000 g/t. The typical Pt : Pd ratio is 30 : 1. The precious metal minerals are represented by native platinum, gold, as well as alloys with continuous miscibility within the Pt0.89Pd0.1-Pt0.6Pd0.4 and Pt0.05Cu0.35-Pt0.35Cu0.65 series. The platinum phase always contains gold, and vice versa. Platinum stibiopalladinite is identified. The platinum mineralization is deposited in vugs of the quartz-hematite rocks, which are filled with drusy quartz, and in vugs in felsites, where platinum minerals are associated with colloform quartz. The study of fluid inclusions in quartz intergrown with platinum minerals indicates that the ore deposition occurred at 370-50 degrees C from low-density high-temperature (0.4-0.7 wt % NaCl-equiv.) and high-density low-temperature (15.5-21.1 wt % NaCl-equiv.) Na-Ca-K-Fe chloride solutions. The data on the composition of aqueous extracts indicate that the ore-forming system contained solutions related to both the Bushveld magma and deep buried waters.