Ancient helium and tungsten isotopic signatures preserved in mantle domains least modified by crustal recycling.

Rare high-He/He signatures in ocean island basalts (OIB) erupted at volcanic hotspots derive from deep-seated domains preserved in Earth's interior. Only high-He/He OIB exhibit anomalous W-an isotopic signature inherited during the earliest history of Earth-supporting an ancient origin of high He/He. However, it is not understood why some OIB host anomalous W while others do not.