概括
研究人员测量了正酸盐β相的弹性特性. 这项研究证实,400公里的地震不连续性很可能是由于地球地幔中的奥利文-改性旋转转变.
科学领域:
- 矿物物理 矿物物理
- 地质物理学 地质物理学
- 材料科学 材料科学 材料科学
背景情况:
- 地球的地幔包含不连续性,例如400公里的地震不连续性,这标志着地震波速度的显著变化.
- 正酸 (Mg(2) SiO(4)) 存在于不同的阶段,包括橄和修饰的旋 (β) 结构,它们在不同的压力和温度下是稳定的.
研究的目的:
- 测量正酸盐修饰的旋转相的单晶弹性模块.
- 为了研究橄-改性旋转相过渡在解释地球地幔400公里的地震不连续性的作用.
主要方法:
- 在高压 (22 GPa) 和温度 (2000°C) 下合成了单晶正酸盐 (β阶段).
- 布里卢恩光谱法被用来测量在环境条件下合成的单晶的弹性模量.
主要成果:
- 成功测量了Mg(2) SiO(4) 修改的旋转相的弹性模块.
- 一个大约40%的橄石的地幔组成与观察到的弹性特性和400公里的地震不连续性是一致的.
- 400公里的不连续性可以归因于从橄烯到改性螺旋烯的相位过渡.
结论:
- 实验数据支持这样的假设,即400公里的地震不连续性是由奥利文转变为修改后的旋转相过渡引起的.
- 需要的橄素丰度低于一些火矿石模型预测的,但火矿石仍然是可能的地幔组成.
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