Complete solid-solution between Na<sub>3</sub>Al<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>and Mg<sub>3</sub>Al<sub>2</sub>(SiO<sub>4</sub>)<sub>3</sub>garnets at high pressure
書誌事項
- 公開日
- 2006-01
- DOI
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- 10.2138/am.2006.2053
- 公開者
- Mineralogical Society of America
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説明
Syntheses along the Mg 3 Al 2 (SiO 4 ) 3 -Na 3 Al 2 (PO 4 ) 3 join were carried out in the 15-17 GPa range at temperatures between 1200 and 1600 °C. An Na 3 Al 2 (PO 4 ) 3 compound of garnet-like structure, with a cubic-cell parameter of 11.579(2) A, was synthesized and characterized. Intermediate compositions are also found to crystallize in the garnet structure. Between pyrope and Na 3 Al 2 (PO 4 ) 3 , the cubic unit-cell volume increases by 3.1%. In addition, nominal compositions, Mg 2 . 5 Na 0 . 5 Al 2 Si 2 . 5 P 0 . 5 O 1 2 and Mg 2 Na 1 Al 2 Si 2 P 1 O 1 2 , were run at 3 GPa and 875 °C. They yielded garnet, among other phases, but with no significant phosphorus incorporation as indicated by a pyrope-like unit-cell volume. Phosphorus content in pyrope from the UHP Dora-Maira quartzites appears as a potential pressure indicator where UHP garnet coexists with phosphate minerals. The P-content in upper mantle garnets can be used as a probe of phosphorus activity in the host rock.
収録刊行物
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- American Mineralogist
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American Mineralogist 91 (1), 211-215, 2006-01
Mineralogical Society of America