Lead supervisor: Marie Edmonds, Earth Sciences
Co-supervisor: Penny Wieser, UC Berkeley
Brief summary:
The 1868 eruption of Mauna Loa, Hawai'i erupted crystal-rich picrites whose geochemistry may be used to understand the plumbing system and eruption triggering process for eruptions at this hazardous volcano.
Importance of the area of research concerned:
The 1868 eruption of Mauna Loa, Hawai'i, began at the summit crater on 27th March 1868. The following day, a large earthquake (M7.0) occurred in Ka'u, on the south flank, and seismicity intensified over the following days, culminating in a much larger earthquake on 2 April (M7.9), which caused landslides, damage to buildings, and a tsunami up to 6 meters high off Ka'u. On 7th April, lava began to erupt from a fissure low on the south west flank of Mauna Loa and around 40 km down-rift. The lavas erupted were picrites: tholeiitic melts that had accumulated substantial amounts of high-Fo olivine to yield a bulk MgO content of ~ 20 wt%. This sequence of events is one that plays out in many Kīlauea and Mauna Loa eruptions, where eruptions begin at the summit and move down-rift following a large earthquake; understanding this sequence is clearly critical for hazard assessment. The crystal cargo contains an archive of information related to magma storage in the summit and rift, which may be interpreted by building on recent studies of Kīlauea olivine crystal cargoes, which indicate remobilisation of crystals from prolonged storage in a sub-caldera mush.
Project summary :
This project aims to characterise the crystal cargo of the 1868 picritic lava flow of Mauna Loa, Hawai'i, in terms of major and trace elements, and in terms of melt inclusion major and trace elements. The diversity and composition of the crystals and their inclusions will be compared to long-term records of Mauna Loa geochemistry, and to the geochemistry of cumulate nodules in other Mauna Loa rocks to build a physical and chemical understanding of the magmatic storage region beneath Mauna Loa how it may evolve with time.
What will the student do?:
The student will carry out fieldwork in Hawai'i to acquire samples of the 1868 Mauna Loa lava flow, and of older deposits on Mauna Loa’s SW rift zone that host cumulate nodules. The student will carry out petrological and geochemical characterisation of the samples, incorporating a range of bulk and microanalytical techniques, and will construct a framework of understanding to explain their origin and what they may tell us about the structure of the magma storage region.
References - references should provide further reading about the project:
Norman, M. D. & Garcia, M. O. Primitive magmas and source characteristics of the Hawaiian plume: petrology and geochemistry of shield picrites. Earth and Planetary Science Letters 168, 27-44, doi:http://dx.doi.org/10.1016/S0012-821X(99)00043-6 (1999).
Tilling, R. I., Rhodes, J. M., Sparks, J. W., Lockwood, J. P. & Lipman, P. W. Disruption of the Mauna Loa magma system by the 1868 Hawaiian earthquake: Geochemical evidence. Science 235, 196-199 (1987).
Wieser, P. E., Edmonds, M., Maclennan, J., Jenner, F. E. & Kunz, B. E. Crystal scavenging from mush piles recorded by melt inclusions. Nature communications 10, 1-11 (2019).
Applying
You can find out about applying for this project on the Department of Earth Sciences page.