作为地幔钻石的摇篮的深度超热结残留物
Carl Walsh1, Balz S Kamber2, Emma L Tomlinson3
1School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, Queensland, Australia.
Nature
|March 16, 2023
概括
古代大陆的强度来自深度的热融, 而不是浅层的过程. 新的模型显示,在200公里深处的融化中,
科学领域:
- 地质化学
- 石油学
- 地动力学
背景情况:
- 古老的坑是深的,凉爽的,硬的, 根源延伸到钻石的稳定区域.
- 克拉顿的强度归因于大量的化提取,导致了凉爽而刚硬的石化层.
- 现有模型提出浅层融化后的深层根形成, 但这项研究挑战了这一点.
研究的目的:
- 研究火山口形成的热力学和地化学条件.
- 模拟融过程,产生在岩根中发现的酸橄.
- 为了使岩根的组成与观察到的地质特征如绿石带相协调.
主要方法:
- 高温化的热力学和地化学建模.
- 封闭系统和开放系统模拟地幔融.
- 在石根和钻石内含物中分析矿物成分.
主要成果:
- 深度融化 (大约 在非常高的温度下 (≥1,800°C) 成功地重现了岩地幔的矿物成分.
- 模拟的岩石演变为富含和的形式,与表面绿石带的观测相一致.
- 缺乏Ti-贫的岩石表明,开放系统的相互作用比先进的封闭系统融更为显著.
结论:
- 岩根可能是通过深度,超热融形成的, 挑战浅模型.
- 开放式系统过程涉及更深层的液体和耐火地幔化对于岩形成至关重要.
- 钻石的形成可能与岩根的减少条件有关,受超热化和古代热潮的影响.
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