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Experimental determination of the solubility of platinum in silicate meltsстатья
Информация о цитировании статьи получена из
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Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 6 декабря 2018 г.
- Авторы: Borisov A., Palme H.
- Журнал: Geochimica et Cosmochimica Acta
- Том: 61
- Год издания: 1997
- Издательство: Pergamon Press Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: 4349
- Последняя страница: 4357
- Аннотация: We report here new experimental results on the solubility of Pt in silicate melts at one atmosphere total pressure. Experiments were made with two different melt compositions: an anorthite-diopside eutectic and a CaO-free system (3SiO2MgOAl2O3, by weight). Oxygen fugacities ranged from pure oxygen to 10-8 atm, and temperatures from 1300 to 1560°C. Glass samples were analysed after the experiments by instrumental neutron activation analysis (INAA). In experiments with An-Di melts isotopically enriched 40Ca (and correspondingly depleted 46Ca) was used to reduce the background from 47Sc produced by neutron activation of 46Ca. In this way the interference was reduced by a factor of 500, allowing the determination of Pt in glass samples by INAA down to a concentration of about 50 ppb. Over five orders of magnitude in oxygen fugacity, from pure oxygen to an fO2 of 10-5 atm, a systematic decrease of the Pt solubility with decreasing fO2 was observed. The slope of the log (Pt solubility) vs. log fO2 correlation suggests a formal valence of +2 for Pt in the silicate melt, independent of temperature. The solubility in the CaO-free melt is about ¼ of an order of magnitude lower than for the An-Di melt. At oxygen fugacities below 10-5 atm results show a large scatter. We suspect that formation of Pt nuggests leads to very inhomogeneous distribution of Pt in the melt. A literature survey shows large variations in Pt solubilities, determined by various authors. These discrepancies primarily result from the formation of Pt nuggets. A new mechanism of PGE nugget formation is suggested. The formation of PtFe alloys predicted to occur in terrestrial magmatic melts may be important for fractionating Pt from other noble metals.
- Добавил в систему: Борисов Александр Александрович
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | GCA61_Pt-97.pdf | GCA61_Pt-97.pdf | 769,6 КБ | 1 декабря 2018 [aborisov] |