CARBONATITIC MELTS ALONG THE SOLIDUS OF MODEL LHERZOLITE IN THE SYSTEM CAO-MGO-AL2O3-SIO2-CO2 FROM 3 TO 7 GPA
- DSpace Home
- →
- Геология России
- →
- ELibrary
- →
- View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.
dc.contributor.author | Dalton J.A. | |
dc.contributor.author | Presnall D.C. | |
dc.date.accessioned | 2020-12-31T08:31:22Z | |
dc.date.available | 2020-12-31T08:31:22Z | |
dc.date.issued | 1998 | |
dc.identifier | https://elibrary.ru/item.asp?id=13703861 | |
dc.identifier.citation | Contributions to Mineralogy and Petrology, 1998, , 2, 123-135 | |
dc.identifier.issn | 0010-7999 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/21892 | |
dc.description.abstract | We have experimentally determined the soli-dus position of model lherzolite in the system CaO-MgO-Al 2 O 3 -SiO 2 -CO 2 (CMAS.CO 2) from 3 to 7 GPa by locating isobaric invariant points where liquid coex-ists with olivine, orthopyroxene, clinopyroxene, garnet and carbonate. The intersection of two subsolidus re-actions at the solidus involving carbonate generates two invariant points, I 1A and I 2A , which mark the transition from CO 2 -bearing to dolomite-bearing and dolomite-bearing to magnesite-bearing lherzolite respectively. In CMAS.CO 2 , we ®nd I 1A at 2.6 GPa/1230 °C and I 2A at 4.8 GPa/1320 °C. The variation of all phase composi-tions along the solidus has also been determined. In the pressure range investigated, solidus melts are carbon-atitic with SiO 2 contents of <6 wt%, CO 2 contents of ~ 45 wt%, and Ca/(Ca+Mg) ratios that range from 0.59 (3 GPa) to 0.45 (7 GPa); compositionally they resemble natural magnesiocarbonatites. Volcanic magnesiocar-bonatites may well be an example of the eruption of such melts directly from their mantle source region as evi-denced by their diatremic style of activity and lack of associated silicate magmas. Our data in the CMAS.CO 2 system show that in a carbonate-bearing mantle, solidus and near-solidus melts will be CO 2 -rich and silica poor. The widespread evidence for the presence of CO 2 in both the oceanic and continental upper mantle implies that such low degree SiO 2 -poor carbonatitic melts are com-mon in the mantle, despite the rarity of carbonatites themselves at the Earth's surface. | |
dc.title | CARBONATITIC MELTS ALONG THE SOLIDUS OF MODEL LHERZOLITE IN THE SYSTEM CAO-MGO-AL2O3-SIO2-CO2 FROM 3 TO 7 GPA | |
dc.type | Статья |
Files in this item
This item appears in the following Collection(s)
-
ELibrary
Метаданные публикаций с сайта https://www.elibrary.ru