| Title | Experimental diopsidite: Implications for natural diopsidite genesis through fluid-melt-mantle peridotite reaction |
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| Author | Borisova, A Y ;
Ceuleneer, G; Zagrtdenov, N R; Safonov, O G; Toplis, M J |
| Source | Mineralogy and Petrology 2021 p. 489-495, https://doi.org/10.1007/s00710-021-00759-7  Open Access |
| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210502 |
| Publisher | Springer |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Subjects | mineralogy; Science and Technology; igneous and metamorphic petrology; diopside; oceanic lithosphere; peridotites; mantle; oceanic crust |
| Illustrations | tables; photomicrographs; phase diagrams; models |
| Released | 2021 08 19 |
| Abstract | Occurrences of diopsidites, rocks made predominantly of gem-like diopside whose composition precludes a purely igneous origin, allow tracking the pathway of high-temperature fluids and fluid-saturated
melts in the oceanic lithosphere in vicinity of the mantle-crust transition zone (the Moho) and the adjacent mantle in an oceanic setting. We have experimentally explored the origin of the mantle diopsidites by reacting serpentinite with synthetic
haplobasaltic glass (corresponding to anorthite-diopside eutectic at 0.1 MPa pressure) at 900 and 1250 °C, and 0.2 GPa pressure for 120 h. At 900 °C, no reaction is observed in the sample; in contrast, in the experimental runs heated to 1250 °C, we
distinguish two mineral associations (1) early Al-poor diopside [Mg# = Mg/(Mg + Fe) = 99 ± 1; Al2O3 = 1.9 ± 1.6 wt%] with the diopside-hosted forsterite ( Fo99.2 ± 0.1) inclusions and (2) late Al-enriched diopside (Mg# = 98 ± 1; Al2O3 = 3.7 ± 2.8
wt%). Our experiments confirm that mantle diopsidites can be produced at > 1100 °C in response to partial melting of hydrated peridotite (serpentinite) in the presence of haplobasaltic melt and aqueous fluid at the conditions typical of the
mantle-crust transition zone and the shallow mantle beneath oceanic spreading ridges. |
| Summary | (Plain Language Summary, not published)
Diopsidites are rocks made predominantly of gem-like diopside. We have experimentally explored the origin of the mantle diopsidites by reacting
serpentinite with synthetic haplobasaltic glass (corresponding to anorthite-diopside eutectic at 0.1 MPa pressure) at 900 and 1250 °C, and 0.2 GPa pressure for 120 h. No reaction occurred at 900 °C. However at 1250 °C reaction happened and we were
able to distinguish two mineral associations (1) early Al-poor diopside [Mg#=Mg/(Mg+Fe)=99±1; Al2O3=1.9±1.6 wt%] with the diopside-hosted forsterite (Fo99.2 ± 0.1) inclusions and (2) late Al-enriched diopside (Mg#=98±1; Al2O3=3.7±2.8 wt%). These
experiments confirm that mantle diopsidites can be produced at >/= 1100 °C and at conditions typical of the mantle-crust transition zone and the shallow mantle beneath oceanic spreading ridges. |
| GEOSCAN ID | 329376 |
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