旋转交叉和富含铁的酸盐在地球深层地幔中融化
Ryuichi Nomura1, Haruka Ozawa, Shigehiko Tateno
1Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
Nature
|April 26, 2011
概括
在地球深层地幔的极端压力下,富含铁的酸盐变得比固体更密集. 这种由铁的旋转交叉驱动的密度反转,对行星进化和核心-地幔边界结构产生了深远的影响.
科学领域:
- 地质物理学 地质物理学
- 矿物物理 矿物物理
- 行星科学 行星科学
背景情况:
- 酸融体的密度通常低于固体.
- 行星内部的高压可以改变相对于固体的融化密度.
- 在高压下化的铁丰富是密度逆转的一个关键因素.
研究的目的:
- 为了研究整个地幔压力范围内的酸盐和固体之间的铁分区.
- 为了确定酸盐融化变得比地球深层地幔中固体更密的压力.
- 了解密集融对地球热和化学进化的影响.
主要方法:
- 在高压实验中测量了铁在 (Mg,Fe) SiO ((3) 矿和矿之间的分离.
- 对冲击波实验的分析.
- 在 (Mg{0.95) Fe{0.05)) SiO{3) 玻璃上进行X射线发射光谱,以探测铁的自旋状态.
主要成果:
- 铁的分离显示了高于~76 GPa的急剧变化,导致融物中的铁含量显著增加.
- 在约70GPa的酸盐融中,铁的旋转交叉被确定为观察到的分区变化的原因.
- 酸盐液体在下层地幔中大约在1800公里深处变得比共存的固体更密.
结论:
- 密集的酸盐融可能存在于早期地球的深层地幔中,可能形成高达1000公里厚的层.
- 这些密集化的分量结晶可以解释核心-地幔边界观察到的结构.
- 这些发现为地球深层过程和核心-地幔相互作用提供了一个统一的模型.
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