在蒸汽或超临界大气层下形成的火星原始粘土
Kevin M Cannon1,2, Stephen W Parman1, John F Mustard1
1Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island 02912, USA.
Nature
|December 9, 2017
概括
火星上的粘土矿物质很可能是由岩海洋冷却过程中的密集蒸汽大气形成的, 而不是液态水. 这种原始的粘土层在火星地深处存活下来,解释了其当前的分布和地密度.
科学领域:
- 星球科学
- 地质学
- 天体生物学
背景情况:
- 在火星的诺亚时代 (4.1 - 3.7 亿年前) 的地形中,有大量的粘土矿物质.
- 之前的理论认为粘土形成是通过基岩地与液态水的反应.
- 火星土壤的起源仍然是行星进化的一个关键问题.
研究的目的:
- 提出并测试火星粘土形成的替代假设.
- 研究密集的蒸汽/超临界大气在粘土生成中的作用.
- 模拟火星上的原始粘土的长期命运和保存.
主要方法:
- 在早期火星大气条件下的粘土形成的实验模拟.
- 模拟地的演变,以追踪粘土层的生存和分布.
- 在火星地质观测的背景下分析实验数据和模型输出.
主要成果:
- 实验证据支持在高压和高温下从蒸汽/二氧化碳大气中快速形成粘土.
- 岩层进化模型显示,原始的粘土在撞击和火山物质的埋葬中幸存下来.
- 模拟的粘土层演化结果是有限的,与轨道数据一致的深度暴露.
结论:
- 在岩海洋冷却过程中,密集的蒸汽/超临界大气是火星粘土的主要来源.
- 深层粘土层的生存解释了目前的粘土分布和火星地的低密度.
- 这一发现提升了我们对早期火星水球和地质过程的理解.
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