Petrology of Koko Rift basalts: Hawai‘i's most recent and atypical rejuvenation stage eruptive sequence

Rejuvenated volcanism is a worldwide phenomena occurring on many volcanic oceanic islands in all of the major ocean basins (e.g., Samoa, Madeira, Mauritius). This plume-related follows main edifice-building stage after hiatus variable duration 0.6–2 Myrs Hawai‘i). Hawaiian rejuvenated basalts typically have high MgO contents (>10 wt%) and carry upper mantle xenoliths . Thus, these magmas are assumed to ascended rapidly through crust. The erupted along Koko Rift Honolulu, Hawai‘i unusual their large range (5.4–11.4 wt%), absence history magma mixing. youngest area (67 ± 2 ka) its best developed rejuvenation-stage rift system (15-km long with 12 several minor subaerial submarine eruptive centers). Here we report first systematic petrologic investigation better understand this most recent example volcanism. New textural mineral chemical evidence indicates was stored later mixed produce lavas 10–11 wt% MgO. lower (5–6 were probably byproducts initial hybrid magma, subsequent crystal fractionation then second mixing event. relatively moderate forsterite (84–85%) higher may be related development crustal within rift. record storage fractionation, two episodes unique among • at 67 ka. Volcanism Honolulu for history. Lavas widely unlike other basalts. 15-km centers.