在板块运动中证据显示下层地幔板块透阶段
Saskia Goes1, Fabio A Capitanio, Gabriele Morra
1Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK. s.goes@imperial.ac.uk
Nature
|February 22, 2008
概括
年轻的构造板块曲并更快地沉入下层地幔,与平坦的旧板块不同. 这种潜伏动态的差异对地球产生影响.
科学领域:
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
- 地幔动力学地幔动力学
背景情况:
- 寒冷的石化层的降温是地球板块构造和地幔对流的关键.
- 潜板透到下层地幔的机制和程度仍在争论中.
- 下地幔板的透对地球的化学和热演变有重大影响.
研究的目的:
- 为了识别潜水板透到下层地幔的事件.
- 调查石灰岩层年龄对俯冲动态和地幔透的影响.
主要方法:
- 在地球的俯冲区中对纪板块运动与动态上层地幔模型进行比较.
- 由下降板的密度驱动的模型.
- 对地震图像的分析显示了沉降物质的分布.
主要成果:
- 较旧的石灰岩层以与基于板块密度的模型相一致的速度沉降.
- 较年轻的石化层 (<60 Myr) 沉降速度高达两倍,沟运动最小.
- 地震数据支持在上层和下层地幔中沉积物质分布的模型.
结论:
- 年轻的石质层在遇到下层地幔时曲和变厚,增加浮力和沉降速度.
- 较古老的石化层往往位于下层地幔过渡区的平面上方.
- 这种依赖年龄的机制有助于快速穿透下层地幔,并证明了依赖时间的地幔流动.
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