最早的火星地的起源和年龄来自石NWA 753333
M Humayun1, A Nemchin, B Zanda
1Department of Earth, Ocean and Atmospheric Science, and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Nature
|November 22, 2013
概括
石西北非洲 (NWA) 7533被认定为火星 regolith breccia,为早期火星地的形成和组成提供了洞察力. 这一发现为地球提供了关键的证据.
科学领域:
- 行星科学 行星科学
- 地质化学 地质化学
- 宇宙化学 宇宙化学
背景情况:
- 火星的南部高地,古老的火山口地形,是了解早期行星分化的关键.
- 在此之前,没有发现过火星地质层的突,这限制了对早期火星材料的直接分析.
研究的目的:
- 为了识别和描述火星的 regolith breccia.
- 用石分析研究早期火星地的分化和组成.
- 为了估计火星地的厚度.
主要方法:
- 分析了7533号西北非洲 (NWA) 石 (与NWA 7034结合).
- 岩组成部分的岩石和地化学分析,包括火性质的岩石和冲击融化岩石.
- 石测年法用于确定年龄和干扰事件.
- 测量 siderophile 和不兼容元素的丰度.
主要成果:
- NWA 7533被认定为一个多物质岩,可能是火星的 regolith 岩,有大量的石 siderophiles.
- 石内部的旋体的年龄为4428±2500万年,以后的干扰为1712±8500万年.
- 地化学数据表明,在火星历史的前1亿年内,地的早期分化.
- 估计火星地的平均厚度为50公里.
结论:
- NWA 7533提供了火星 regolith breccia的第一个直接证据,证实了早期地的分化.
- 火星地及其挥发性库存是在地球历史的早期形成的,与地球和月球同时存在.
- 石的地球化学数据支持火星地厚度的地球物理估计.
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