在地球的火山热点和中海山脊的相对温度上
Xiyuan Bao1, Carolina R Lithgow-Bertelloni1, Matthew G Jackson2
1Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA.
概括
海洋热点的温度差异很大, 许多热点不够热, 无法形成深层地幔. 这挑战了现有的地幔羽毛和火山活动模型.
科学领域:
- 地质学
- 地质化学
- 地幔动力学
背景情况:
- 火山热点传统上与热,深层地幔上升有关,其过度温度 (T_ex) 比中洋山脊高得多.
- 现有的热点T_ex估计在地理上是有限的,并且经常显示不一致,阻碍了全面的理解.
研究的目的:
- 它们可以同时推断海洋热点和中海山脊的温度.
- 通过将地震速度转换为温度来评估海洋热点的热状态和起源.
主要方法:
- 使用地震速度数据推断海洋热点和中海山脊的温度.
- 分析过度温度 (T_ex) 以将热点分类为热点,冷点或不足热点.
主要成果:
- 大约45%的喷气热点被归类为热点 (T_ex ≥155°C),而15%的热点为冷点 (T_ex ≤36°C),40%的热点不够热,无法活跃上升 (50°C ≤T_ex ≤136°C).
- 热点呈现出高-3/-4比率和浮力流量,与冷热点不同.
- 冷热点可能来自较浅的上层地幔深度,或通过小规模的对流来冷却.
结论:
- 海洋热点的热结构比以前的假设更为多样化,其中很大一部分缺乏深层地幔羽毛养的预期高温.
- 这些发现表明,一些热点可能有较浅的起源或经历显著的冷却过程,需要对地幔羽流动力学的模型进行修订.
- 独特的地化学特征 (例如,同位素比率) 区分热点和冷点,提供它们独特的热状态和潜在来源的线索.
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