Extrinsic controls on the evolution of Hawaiian ocean island volcanoes

Abstract

[1] Extrinsic parameters that affect the evolution of magmatic systems within and beneath ocean island volcanoes include physical variables such as confining pressure, which controls magma degassing, and temperature of the underlying lithosphere and crust, which controls magma crystallization during ascent. Other extrinsic parameters are environmental variables coupled to the hydrosphere and atmosphere such as hydrothermal circulation systems and even rainfall. All these extrinsic factors interact with intrinsic parameters, such as magma supply rates or composition, to modulate the evolution of magma chambers and the petrologic processes that take place within them.Components: 6607 words, 1 table.

Seismic evidence for a crustal magma reservoir beneath the upper east rift zone of Kilauea volcano, Hawaii

“…Although previous velocity studies suggested that melt might be within the oceanic crust (e.g., Hill and Zucca, 1987;Park et al, 2007), this is the fi rst geophysical observation for magma storage under a Hawaiian volcano in its shield-building phase with a high rate of magma supply. It is consistent with the petrologically inferred crustal reservoir of Loihi, a submarine volcano also in its shield-building phase (Clague and Dixon, 2000). Magma reservoirs in the oceanic crust stand in contrast to deep magma reservoirs at the crust-mantle boundary (15-20 km depth) that are associated with late phases of Hawaiian volcanism (Frey et al, 1990;Clague and Dixon, 2000), when magma supply rates are too low to maintain shallow reservoirs.…”

Deep intrusions, lateral magma transport and related uplift at ocean island volcanoes

“…In the Hawaiian Islands seismic data revealed a 200 km wide, 3 km thick transition zone in the lowermost crust and uppermost mantle beneath Oahu, which was interpreted as a sill-dominated plutonic complex formed by rising magma (ten Brink and Brocher, 1987). Seismic tomography revealed a large volume of intrusive bodies within the oceanic crust beneath the Louisville hotspot track that were emplaced when the crust was young (∼10 Myr) and warm (Contreras-Reyes et al, 2010). Our data suggest that intracrustal intrusions are common not only for young but also for very old (Jurassic to Cretaceous) oceanic crust.…”

“…Magma reservoirs are established at an early stage of volcano evolution (Clague and Dixon, 2000;Gudmundsson, 2012). This may be exemplified by Funchal Ridge, a cluster of small (<600 m) seamounts up to 50 km from Madeira.…”

“…They are partly formed of, and are underlain by, magmatic intrusions that can be of significantly larger volume than volcanic outputs (Contreras-Reyes et al, 2010;Crisp, 1984;ten Brink and Brocher, 1987). Field studies at deeply incised volcanoes show that many, perhaps most, shallow basaltic intrusions are steeply dipping sheets (dykes) that have either fed eruptions or became stalled in the shallow crust.…”

Slope failure and volcanic spreading along the submarine south flank of Kilauea volcano, Hawaii

“…Flank seismicity, for example, of the magnitude of the great 1868 Ka'u (M $ 8.0) or the 1975 Kalapana earthquakes (M7.2) would certainly shake the submarine flanks, dislodging precarious slope deposits, but such seismicity accompanies flank sliding and must be ongoing, at least for an extensive period of volcanic evolution. Catastrophic flank collapse of the scale observed here, and documented around the islands, is thought to occur relatively late in the evolution of the volcano [e.g., Moore et al, 1989], and may coincide with unusually energetic volcanic eruptions, perhaps explosive in nature [Clague and Dixon, 2000;McMurtry et al, 1999]. Kilauea volcano has experienced at least two extraordinary phreatomagmatic eruptions within the last 50,000 years, both associated with collapse of the summit caldera, and responsible for massive ash deposits dated at 49 and 23-29 ka [Clague et al, 1995].…”