LIQUIDUS SURFACES OF ULTRACALCIC PRIMITIVE MELTS: FORMATION CONDITIONS AND SOURCES
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dc.contributor.author | Médard E. | |
dc.contributor.author | Schiano P. | |
dc.contributor.author | Schmidt M.W. | |
dc.date.accessioned | 2022-04-04T07:16:52Z | |
dc.date.available | 2022-04-04T07:16:52Z | |
dc.date.issued | 2004 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=13736867 | |
dc.identifier.citation | Contributions to Mineralogy and Petrology, 2004, 148, 2, 201-215 | |
dc.identifier.issn | 0010-7999 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/36840 | |
dc.description.abstract | CaO-rich, Al2O3-poor ultracalcic primitive melts occur at mid-ocean-ridges, back-arc basins, ocean islands and volcanic arcs. They are subdivided into a “nepheline-normative” alkaline-rich, silica-poor group uniquely found in arcs and in “hypersthene-normative” fairly refractory melts which occur in all of the above environments. The high CaO contents (to 19.0 wt%) and CaO/Al2O3 ratios (to 1.8) exclude an origin from fertile lherzolites at volatile-absent conditions. Experimental investigation of the liquidus of a hypersthene-normative and a nepheline-normative ultracalcic melt results in quite distinct pressure-temperature conditions of multiple saturation: whereas the hypersthene-normative liquid saturates in olivine + clinopyroxene at 1.2 GPa and 1,410°C, this occurs at 0.2 GPa and 1,220°C for the nepheline-normative ultracalcic liquid. Our results in combination with melting experiments from the literature suggest that hypersthene-normative melts result from melting of a refractory olivine + clinopyroxene ± orthopyroxene source at elevated mantle temperatures. Contrasting, nepheline-normative ultracalcic melts form from wehrlitic cumulates in the arc crust; to account for the high alkaline and low silica contents, and the relatively low temperatures, source wehrlites must have contained amphibole. | |
dc.title | LIQUIDUS SURFACES OF ULTRACALCIC PRIMITIVE MELTS: FORMATION CONDITIONS AND SOURCES | |
dc.type | Статья |
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