Melting in the Mg2SiO4-H2O system at 3 to 12 GPa
Melting in the Mg2SiO4-H2O system at 3 to 12 GPa
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在 Mg2SiO4-H2O 系统中在 3 至 12 GPa 下熔化
DOI：
10.1029/92gl03008
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发表时间：
1993
影响因子：
5.2
通讯作者：
R. Luth
中科院分区：
文献类型：
--
作者：
R. Luth
在多砧装置上研究了3 ~ 12 GPa压力下镁橄榄石（Mg_2SiO_4）在H_2O存在下的熔融过程，以确定地幔橄榄岩系统中含水固相线的最高温度。固相线具有负斜率至12 GPa，尽管在> 9 GPa时固相线处与镁橄榄石和蒸气共存的相E（含水硅酸镁）稳定。在所有运行产品中的大量淬火蒸汽沉积物表明硅酸盐在蒸汽中的广泛溶解度;然而，没有直接证据表明蒸汽中的不一致溶液达到9 GPa。在> 9 GPa时，固相线上Fo + PhE + V的共存需要Mg/Si = 2。硅酸盐熔体和含水蒸汽在该系统中保持不混溶相至>12 GPa。
根据目前对地幔温度分布的估计，软流圈地幔中的水蒸气只有在150 GPa（160 km深度）以下才能存在。在更深的地方，水将以含水硅酸盐熔体的形式存在，而不是以自由蒸汽的形式存在。这个深度是最大值，因为含水橄榄岩系统的固相线温度低于端元Mg 2SiO 4 −H2O系统。在较冷的俯冲板中，含水蒸汽可以持续到过渡区。
The melting of forsterite (Mg2SiO4) in the presence of H2O was studied from 3 to 12 GPa in a multiple-anvil apparatus to constrain the maximum temperature of the hydrous solidus in peridotitic systems relevant to the Earth's mantle. The solidus has a negative slope to 12 GPa, despite the stabilization of Phase E (a hydrous magnesium silicate) coexisting with forsterite and vapour at the solidus at > 9 GPa. Abundant quench vapour deposits in all the run products indicate extensive solubility of silicate in the vapour; however, there is no direct evidence for incongruent solution in the vapour to 9 GPa. At > 9 GPa, the coexistence of Fo + PhE + V at the solidus requires Mg/Si≠2 in the vapour. Silicate melts and hydrous vapours remain immiscible phases in this system to >12 GPa.
Given current estimates of the temperature distribution in the mantle, a hydrous vapour can exist in the asthenospheric mantle only below ∼5 GPa (∼160 km depth). At greater depths, water would be present in a hydrous silicate melt rather than in a free vapour. This depth is a maximum, because solidus temperatures in hydrous peridotite systems would be lower than those in the endmember Mg2SiO4−H2O system. In cooler subducting slabs, a hydrous vapour could persist down to the transition zone.
影响因子：
3.9
作者：
MCKENZIE, D;BICKLE, MJ
通讯作者：
BICKLE, MJ