The origin of volcanic flux variations along Pacific hotspot tracks: Plume-lithosphere interaction vs. plume pulsations

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The volcanic flux at the Hawaiian hotspot generally increased over the last 30-80 Ma, with second-order variations over 10~15 Ma. This significant increase remains unexplained by classic plume theory, which predicts that a plume-head stage with massive volcanic activity is followed by a plume- tail stage with ever decreasing activity. In particular, 25-30 Ma ago there was a sharp increase in the Hawaiian volcanic flux by a factor ~4 that appears to be associated with an increase in Pacific plate motion from ~60 km/Ma to ~100 km/Ma. At about the same time there was a surge across the South Pacific of young low-volume hotspot tracks. It is unclear from our understanding of the poorly sampled Hawaiian track if these volcanic flux variations are related to speed up of the Pacific plate or to pulsations of the Hawaiian plume. In order to explain the coupled observations of faster plate speed and increased volcanic flux we aim to explore three young, relatively low-volume Pacific hotspot tracks. High–precision geochronological data for multiple hotspot tracks is the only way of extracting fundamental new information from the intraplate record about the poorly-sampled young end of the Hawaiian hotspot track. We propose to determine high-precision ages using the next generation of multi-collector mass spectrometer for 111 samples from the Foundation, Easter and Pukapuka-Rano Rahi volcanic tracks. We will use these new data to (1) pinpoint the timing of Pacific plate-speed increases and variations in hotspot volcanic flux, and (2) understand the underlying mechanisms controlling volcanic flux variations at Pacific hotspots.