概括
地球地幔中的螺旋-矿相位过渡从负向正的Clapeyron斜率在2000°C以上转移. 这种变化阻碍了寒冷的下流,但允许热升起,从而产生部分层叠的地幔对流.
科学领域:
- 地质物理学 地质物理学
- 矿物物理 矿物物理
- 地球科学 地球科学 地球科学
背景情况:
- 660公里的地幔过渡区是影响全球地幔对流的关键接口.
- 旋-矿相位过渡的克拉佩隆斜率决定了穿过这个边界的地幔流动的行为.
- 以前的研究表明,克拉佩隆的斜率是负的,这意味着上层和下层地幔之间的相互作用有限.
研究的目的:
- 为了研究温度依赖的克拉佩隆斜率对地幔对流动动态的影响.
- 了解螺旋石-矿相位过渡如何影响热的上升和冷板块的下降.
- 为了描述由此产生的地幔流动模式和分层.
主要方法:
- 使用高压实验数据和热力学计算来确定克莱佩隆斜率.
- 执行覆盖层对流的数值模拟,包括温度依赖的相位过渡.
- 分析由此产生的流动结构,包括羽毛升起和下降的行为.
主要成果:
- 在17002000°C以上的温度下,旋-矿过渡的克拉佩隆斜率变为正值.
- 在这些条件下,在660公里的边界处,冷的下流流被显著阻碍.
- 热子很容易上升到上层地幔,导致部分分层和时间依赖的地幔对流.
- 在更高的温度和更高的雷利数值下,地幔分层的明显程度较低.
结论:
- 旋-矿过渡的温度依赖的克拉佩隆斜率在调节地幔对流方面发挥着至关重要的作用.
- 这种相位行为促进了热量通过羽毛从下层到上层地幔的传输.
- 地球的地幔呈现出部分层次的对流体制,受到这种相位过渡的影响,特别是在更热的地区.
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