月球形成撞击体作为地球基本地幔异常的来源
Qian Yuan1,2, Mingming Li3, Steven J Desch3
1School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA. qyuan@caltech.edu.
Nature
|November 2, 2023
概括
地球的大低速度区域 (LLVP) 可能是形成月球的原行星Theia的残余物质. 这种古老的地幔材料可以解释这些深层地球结构的组成.
科学领域:
- 地质学
- 星球科学
- 地球科学
背景情况:
- 地球最下层的地幔包含大陆大小的异常,称为大低速省 (LLVPs).
- 通常将LLVP解释为地幔内的密集,组成上不同的异质性.
研究的目的:
- 调查LLVPs是否可能是形成月球的巨型撞击中的Theia地幔物质 (TMM) 的残余.
- 模拟TMM在地球地幔中的保存和积累.
主要方法:
- 模拟从泰亚到原地球的物质传递.
- 用地幔对流模型来追踪密集TMM在地质时间上的行为.
主要成果:
- 模拟表明,Theia的地幔的一部分可能被纳入原地球的下层地幔.
- 泰亚的地幔材料估计比原地球的地幔密度高2.0-3.5%.
- 密集的TMM块可能会沉没,在核心-地幔边界积聚,形成类似LLVP的结构,直到今天.
结论:
- LLVPs可能是月球形成的巨大撞击的直接后果,代表了被保存的Theia地幔材料.
- 这种撞击驱动的起源表明其他行星体中可能存在类似的地幔异质性.
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