Geochemistry of lavas from the Caroline hotspot, Micronesia: Evidence for primitive and recycled components in the mantle sources of lavas with moderately elevated 3He/4He

Lavas with moderately elevated 3He/4He (up to 12.8 Ra) from Kosrae, as well as lavas from other high-3He/4He localities globally, exhibit evidence for a recycled oceanic crust signature, including elevated Ti concentrations and moderately radiogenic Pb isotopic compositions. This observation suggests that primitive high-3He/4He and recycled reservoirs are intimately associated, and mix, in the deep mantle sources of plumes. Hybrid mantle domains generated in this way serve as the melt source for lavas with elevated 3He/4He from many hotspot localities. Thus, the geochemistry of much of the mantle, including the high-3He/4He domain, may be modified by the addition of subducted materials.