Magma Mixing during the Puu Oo eruption of Kilauea Volcano
Magma erupted in the early stages of the Puu Oo eruption of Kilauea Volcano represented
a mixture of fresh mafic magma and more evolved, higher-MgO magma. The composition of
this hybrid magma changed systematically after the eruption was localized at the Puu Oo
vent. We modelled the magma system at Puu Oo as a well-mixed box model and derived a set
of relationships from mass balance principles describing the proportion of each magma
component in the magma reservoir at any point in time. Constraining this model with
erupted lava compositions and with observed eruption flux rates, we calculate the initial
volume of the magma chamber and its change in time. Comparison with geophysical studies
suggests that two separate reservoirs may exist below Puu Oo: a shallow dike-like reservoir
and a deeper, larger mixing reservoir.
Read More:
P.J. Shamberger, and M.O. Garcia.
Geochemical modeling of magma mixing and magma reservoir volumes during early episodes of Kilauea Volcano’s Pu‘u ‘O‘o eruption.
Bulletin of Volcanology, 69 (4), 345-352 (2006).
Gabbroic & leucocratic summit xenoliths of Hualalai Volcano
A suite of distinctive gabbroic and leucocratic crystalline nodules found at the
summit of Hualalai Volcano records a cumulative history of magmatism at the volcano.
Leucocratic xenoliths are particularly rare on Hawaiian Volcanoes and may be related
to an episode of trachyte (evolved) volcanism ~100 k.y.a. Whole-rock major and trace
element compositions and mineral compositions are consistent with these xenoliths
solidfying from intermediate magmas (mugearites) along the trachyte liquid line of
descent. Because the trachyte episode occured during the transition between shield
and post-shield magmatic stages, conditions of evolving magma may indicate the magma
storage depths during this transition. Clinopyroxene geobarometry, MELTS simulations,
and normative whole-rock compositions all suggest crystallization at moderate pressures
(~3-7 kbar). This may indicate a rapid transition to deep-level magma storage occurring
at the beginning of the shield to post-shield transition.
Read More:
J. Vazquez, P.J. Shamberger, and J.E. Hammer.
Plutonic Xenoliths Reveal the Timing of Magma Evolution at Hualalai and Mauna Kea, Hawaii.
Geology, 35 (8), 695-698 (2007).
P.J. Shamberger, and J.E. Hammer.
Leucocratic & Gabbroic Xenoliths from Hualalai Volcano, Hawai‘i.
Journal of Petrology, 47 (9), 1785-1808 (2006).
Submarine growth of Hualalai Volcano: early magmatic and growth history
Recent submersible dives along the submarine west flank of Hualalai Volcano
have allowed new insights into growth mechanisms operating along this part
of the volcano. Sample petrography, glass geochemistry, and stratigraphy
require that a variety of transport mechanisms juxtaposed materials from multiple
eruptions into individual beds, compacted them into a coherent package of units,
and brought this package to its present depth 10 km from the edge of the North
Kona slump bench. This package includes representatives of both shield and pre-shield
volcaniclastics.
Read More:
J.E. Hammer, M. Coombs, P.J. Shamberger, and J.-I. Kimura.
Submarine sliver in North Kona: A window into the early magmatic and growth history of Hualalai Volcano, Hawaii.
Journal of Volcanology and Geothermal Research, 151 (1-3), 157-188 (2006).
