Mineralogical insights into the 2018 Puna eruption at Kilauea volcano:
magma origins and mixing timescales
After 35 years of fairly steady lava effusion from the Pu’u ‘O’o vent
along Kilauea’s mid portion of the East Rift Zone, a drastic change in
the volcano’s behavior was initiated in May 2018. A series of new
fissures opened between May 3rd and May 9th along the eastern end of the
subaerial ERZ ( >40 km from the summit caldera), feeding a
few short lived, relatively small volume flows. The products from the
early phase of the eruption were dominated by plagioclase and
clinopyroxene phenocrysts, gabbroic glomerocrysts and other crystal
clots likely picked up prior to eruption. The initial activity
transitioned between May 12th and around May 28th to steadier
fountaining, higher effusion rate activity, leading to the formation of
larger volume lava flows and the ensuing destruction of hundreds of
houses and structures within the Puna area. This period marked the
arrival of olivine-bearing Pu’u ‘O’o-like magma to the eruption site.
Since the end of May, activity has focused on a unique vent (Fissure 8).
This contribution examines the crystal cargo from the different magmas
involved in the initial four weeks of the eruption, and their history
through chemical zoning patterns of crystals. We discuss the magmatic
origin of mineral assemblages from the evolved basalt end-member, and
present initial results on timescales of magma interactions prior to
their arrival at the surface from diffusion modeling in olivine.