在非洲和太平洋下面的热化学结构
Allen K McNamara1, Shijie Zhong
1Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA. allen.mcnamara@asu.edu
Nature
|October 21, 2005
概括
地球的潜伏历史塑造了深层地幔结构. 数字模型显示,过去的板块运动在非洲和太平洋下形成了密集的热化学堆,与地震观测结果相匹配.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地球科学 地球科学 地球科学
背景情况:
- 在非洲和太平洋下方的下层地幔中存在大型低速地震异常.
- 这些异常并不能完全由单独的温度变化来解释.
- 之前的模型建议密集的热化学堆,但缺乏几何验证.
研究的目的:
- 为了调查地球的沉降历史是否能产生与地震观测相匹配的下层地幔热化学结构.
- 为了使地震学推断与地幔对流模型相协调.
主要方法:
- 热化学对流的数值建模.
- 使用了三维球形几何.
- 从过去的1.19亿年来,嵌入了板块的速度.
主要成果:
- 潜伏历史成功地产生了与观察到的地震异常相似的热化学结构.
- 密集的物质聚焦在非洲下面的山脊状的堆中.
- 在太平洋下面形成了一个更圆的密集物质堆.
结论:
- 地球的潜伏历史是形成大规模下层地幔结构的关键因素.
- 这些模型与地震学数据保持一致,解释了非洲和太平洋异常的不同形态.
- 这为形成深层地幔热化学堆提供了一种机制.
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