McDonald Islands Phonolitic Lavas: Evidence for Zonation of the Kerguelen Plume

Research on the McDonald Islands reveals evidence of zonation within the Kerguelen mantle plume, a long-lived volcanic hotspot. The study identified a new magma series, the McDonald Series, characterized by distinct geochemical signatures (low εHf, Δ207Pb/204Pb, and Δ208Pb/204Pb) in fresh phonolitic lavas dredged from sea knolls around the islands. These lavas, dated to the Pleistocene-Holocene period (73.7 ± 15.1 ka to 7.0 ± 2.7 ka), suggest a younger, distinct volcanic phase linked to a specific component of the plume. The findings propose that this series, along with older lavas from the Ninetyeast Ridge, provides evidence for chemical and temporal zonation within the Kerguelen plume, challenging previous assumptions about its homogeneity.

Fox, J. M., Falloon, T. J., Carey, R. J., Watson, S. J., Duncan, R. A., Olin, P. H., Arculus, R. J., & Coffin, M. F. (2024). McDonald Islands Phonolitic Lavas: Evidence for Zonation of the Kerguelen Plume. Geochemistry, Geophysics, Geosystems, 25(11). Portico. https://doi.org/10.1029/2024gc011854