Modeling volcano growth on the Island of Hawaii: Deep-water perspectives

Abstract

Recent ocean-bottom geophysical surveys, dredging, and dives, which complement surface data and scientifi c drilling at the Island of Hawaii, document that evolutionary stages during volcano growth are more diverse than previously described. Based on combining available composition, isotopic age, and geologically constrained volume data for each of the component volcanoes, this overview provides the fi rst integrated models for overall growth of any Hawaiian island. In contrast to prior morphologic models for volcano evolution (preshield, shield, postshield), growth increasingly can be tracked by age and volume (magma supply), defi ning waxing alkalic , sustained tholeiitic, and waning alkalic stages. Data and estimates for individual volcanoes are used to model changing magma supply during successive compositional stages, to place limits on volcano life spans, and to interpret composite assembly of the island. Volcano volumes vary by an order of magnitude; peak magma supply also varies sizably among edifi ces but is challenging to quantify because of uncertainty about volcano life spans. Three alternative models are compared: (1) near-constant volcano propagation, (2) near-equal volcano durations, (3) high peak-tholeiite magma supply. These models defi ne inconsistencies with prior geodynamic models, indicate that composite growth at Hawaii peaked ca. 800-400 ka, and demonstrate a lower current rate. Recent age determinations for Kilauea and Kohala defi ne a volcano propagation rate of 8.6 cm/yr that yields plausible inception ages for other volcanoes of the Kea trend. In contrast, a similar propagation rate for the less-constrained Loa trend would require inception of Loihi Seamount in the future and ages that become implausibly large for the older volcanoes. An alternative rate of 10.6 cm/yr for Loa-trend volcanoes is reasonably consistent with ages and volcano spacing, but younger Loa volcanoes are offset from the Kea trend in age-distance plots. Variable magma fl ux at the Island of Hawaii, and longer-term growth of the Hawaiian chain as discrete islands rather than a continuous ridge, may record pulsed magma fl ow in the hotspot/plume source. 40 Ar/ 39 Ar methods to young basalts, especially For permission to copy, contact editing@geosociety.org

Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

“…Buckhorn Mountain is ~9 km north of the 16.5-km-thick measured section of Hirsch and Babcock (2009). If future work can confi rm the young basal age, the entire Crescent section may have accumulated in <1 m.y., a rate similar to the construction of Mauna Loa (Lipman , 1995;Lipman and Calvert, 2013).…”

“…The upper part of the Crescent Formation is blocky to columnar jointed basalt with oxidized fl ow contacts indicative of subaerial eruption and more typical zeolite and smectitic clay alteration, as seen elsewhere in the Coast Range. The Crescent Formation exposures on the Olympic Peninsula span an area a bit larger than the island of Hawaii, and the 16.5 km thickness of the formation is about the same as the 17 km thickness of Mauna Loa, if sub sidence of the seafl oor is accounted for (Lipman, 1995;Lipman and Calvert, 2013). Seismic profi ling indicates that the Crescent Formation is continuous, with high-velocity crust that extends northward to the Metchosin complex, east beneath Puget Sound, and south to the Willapa Hills and Oregon (Trehu et al, 1994;Parsons et al, 1999;Brocher et al, 2001).…”

Why Is Crustal Underplating Beneath Many Hot Spot Islands Anisotropic?

“…The magmatic underplating model of Richards et al (2013) could avoid forming substantial spreading diapirs if the ascent of its ultramafic magma from the plume head were sufficiently diffuse. This seems unlikely, given that melt-ascent of extrusive volcanism is observed to concentrate on scales matching the spacing between hot spot islands (Hieronymus & Bercovici, 2001), or between volcanic centers within islands (Lipman & Calvert, 2013;Moore & Clague, 1992). Diffuse magmatic underplating of a large swell, or an Koch and Manga (1996), who fit their viscous-flow models to coronae with diameters 200-400 km and peak-to-peak topography of 500-1,500 m.…”

The origin of Mauna Loa's Nīnole Hills: Evidence of rift zone reorganization

“…[] and Morgan et al . [] tied the high‐velocity zone beneath the Nīnole Hills to the continuation of Kīlauea's SWRZ [ Lipman and Calvert , ]. Furthermore, Jicha et al .…”