Hotspot lavas exhibit chemical heterogeneity, much of which is ascribed to heterogeneous deep mantle sources that contain various components with distinct composition, origin and age. However, characterizing primary melt compositions and mantle heterogeneity directly is challenging. Here we investigate a global dataset of hotspot lavas to constrain the incompatible-element composition of their parental melts and sources. Trace-element ratios indicate that the compositional heterogeneity of global hotspot lavas is not primary, but reflects processes that hotspot melts undergo as they ascend to the surface. We find the parental melts of these lavas, as well as of kimberlites and basalts from large igneous provinces, to be uniform in their elemental, and radiogenic and noble-gas isotope, composition. We suggest that the parental melts to all of these lavas derive from a depleted and outgassed mantle reservoir that was replenished with incompatible element-enriched material during the Archaean. This interpretation explains the elemental, radiogenic and noble-gas isotope compositions of hotspot lavas without requiring a heterogeneous lower mantle or the long-term survival of undegassed relics from a primordial Earth.

热点熔岩表现出化学异质性，其中大部分归因于非均质的深地幔源，其中包含具有不同成分、起源和年龄的各种成分。然而，直接表征初级熔体成分和地幔非均质性具有挑战性。在这里，我们研究了热点熔岩的全球数据集，以限制其母体熔岩和来源的不相容元素组成。微量元素比率表明，全球热点熔岩的成分异质性不是主要的，而是反映了热点熔岩在上升到地表时所经历的过程。我们发现这些熔岩的母体熔融，以及来自大型火成岩省份的金伯利岩和玄武岩的母体熔融物，它们的元素、放射性和惰性气体同位素组成是均匀的。我们认为，所有这些熔岩的母体熔融都来自一个枯竭和脱气的地幔储层，该储层在太古宙期间被不相容的富含元素的物质补充。这种解释解释了热点熔岩的元素、放射性和惰性气体同位素组成，而不需要异质的下地幔或来自原始地球的未受损遗迹的长期生存。