The trace-element compositions of mantle-derived basalts suggest that the asthenosphere has two distinct melt layers, with unique chemical compositions and physical properties.

中文翻译：

---

双地幔熔体层

幔源玄武岩的微量元素组成表明，软流圈具有两个不同的熔融层，具有独特的化学成分和物理性质。