Phase relation and physical properties of an Al-depleted komatiite to 23 GPa
Phase relation and physical properties of an Al-depleted komatiite to 23 GPa
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23 GPa 的贫铝科马提岩的相关系和物理性质
DOI：
10.1016/s0012-821x(01)00378-8
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发表时间：
2001
影响因子：
5.3
通讯作者：
E. Takahashi
中科院分区：
文献类型：
--
作者：
Yu Nishihara;E. Takahashi
对地幔矿物成分的了解在很大程度上取决于叶熔岩成分的高磷实验。为了更好地了解行星内部，除热熔石以外的成分的相关系和矿物物理性质也可能很重要。对贫铝科马提岩进行了高磷和高温实验，该贫铝科马提岩可以被视为一种硬铁矿组合物。使用多砧装置沿着 5 至 23 GPa、1100 至 1600°C 之间的模型地温进行了 14 项实验。对淬火运行产物的分析表明，在所研究的科马提岩中，橄榄石及其高磷多晶型物（瓦兹利石和尖角橄榄石）的分数为 40-50 vol%，辉石-石榴石相变发生在 13-17 GPa（而黄铁矿的相应值分别为 ∼60 vol% 和 12-15 GPa）。利用相关矿物的热弹性参数计算了科马提岩地幔的密度和地震速度剖面，与过渡带周围地震观测结果以及火山岩的地震观测结果吻合较好。
Knowledge of the mineralogical constituents of the Earth’s mantle depends heavily on high-P experiments of pyrolite composition. In order to understand the planetary interior better, phase relations and mineral physics properties of compositions other than pyrolite may also be important. High-P and high-T experiments were conducted on an Al-depleted komatiite which can be regarded as a kind of piclogite composition. Fourteen experiments were carried out along a model geotherm between 5 and 23 GPa and 1100 and 1600°C with a multi-anvil apparatus. Analyses of quenched run products showed that, in the studied komatiite, the fractions of olivine and its high-P polymorphs (wadsleyite and ringwoodite) are 40–50 vol%, pyroxene–garnet phase transition occurs at 13–17 GPa (while the respective values for pyrolite are ∼60 vol% and 12–15 GPa). The density and seismic velocity profiles of komatiite mantle were calculated using thermoelastic parameters of related minerals, and they showed quite good agreements with those of seismic observations around the transition zone as well as those for pyrolite.