Tohu Paerunga, Mātai AronukuPostgraduate Geology

Polar aeolian sediment distribution, analysis of polar glaciomarine drillcores, terrestrial cold-based glaciers and the interaction with the landscape,
Interpreting marine and terrestrial depositional environments from Paleogene to Quaternary sedimentary rocks in the East Coast of New Zealand. Recent research has focussed on polar dust transport and impact, ice shelf grounding line sedimentology and developing digital tools for geoscience education.

Much of my recent research has focused on identifying patterns and controls of marine biodiversity change, extinction and evolution on geological timescales. One motivation has been the observation that extinction can only truly be understood in hindsight, once a group of organisms has become extinct and it is too late to save them. The fossil record is a history of countless 'natural experiments' in extinction and we can, therefore, use these to understand the drivers and rates of extinction and, perhaps, use this knowledge to help mitigate modern, human-caused extinction. This research has used the fossil records of global and Southern Ocean marine plankton (abundant, single-celled animals and plants that float in the ocean) and New Zealand's outstanding archive of Cenozoic shellfish. This work has involved collaborations with Michael Foote (University of Chicago), Pete Sadler (University of California, Riverside), Steve Meyers (University of Wisconsin), Roger Cooper (formerly of Earth Sciences NZ), Alan Beu (formerly of Earth Sciences NZ), amongst others. As part of this work, I have applied quantitative methods for the analysis of large paleontological datasets in order to generate high resolution time series of evolution and extinction in the fossil record. I have also worked on the development and application of mathematical description of biological shape, as a tool to understand the evolution of groups of related species in the fossil record. Some of this research has involved the integration of molecular (genetic) and morphological data in order to understand evolutionary processes, with collaborator Mary Morgan Richards (Massey University) and students.

I also have had long-standing interest in the Cretaceous geological and biological history of Zealandia, the largely submerged continent on which New Zealand sits. This research includes taxonomic and biostratigraphic studies of Cretaceous shellfish in New Zealand, particularly a group of clams known as inoceramids that lived at the

My research uses geochemical and isotopic tools to investigate the cycling of elements through Earth systems. I am interested in understanding how elements are transferred between Earth's interior, surface environments, oceans, sediments, and biological systems, and what these processes reveal about geological evolution, environmental change, and natural resources.

Current research themes include:

• Subduction zone geochemistry and arc volcanism, including volatile cycling, magma generation, and trace metal behaviour in the Kermadec Arc-Havre Trough region.
• Mantle geochemistry and lithospheric evolution, particularly the composition and history of lithospheric mantle beneath Antarctica.
• Marine and environmental geochemistry, including trace metal cycling in marine sediments and organisms, and the response of marine systems to environmental change.

My research covers a broad range of topics in areas of volcanology, geochemistry and petrology. My earlier career was built around intensive field focussed projects aimed at understanding the physical processes involved in explosive volcanism. In particular, I worked on the eruption and emplacement of ignimbrites (the deposits of large-scale pyroclastic flows) in New Zealand and the USA. Over the last ~15 years my focus has changed into an interest in how the magma (molten rock) that feeds these large eruptions is formed and stored in the Earth’s crust, together with what factors control the timing and dynamics of eruptions.

My research areas have mostly been in the Taupo Volcanic Zone in New Zealand, but I have also worked at Long Valley in California, Yellowstone in Wyoming and in the Valley of Ten Thousand Smokes in Alaska. All these studies have involved numerous collaborators, and many of them have been the focus of student projects.

Recent and current topics include but are not limited to:
+ The dynamics of magma accumulation as shown by mineral-specific records in young eruptives in the Taupo Volcanic Zone
+ The timings of magma ascent in small to large silicic (super-) eruptions, particularly linking melt inclusion records with information from field studies in the Oruanui, Bishop Tuff and Huckleberry Ridge Tuff eruptions
+ The 4-D evolution of the central Taupo Volcanic Zone using 40Ar/39Ar dating on surficial rocks and U-Pb dating techniques on zircons from deeply buried geothermally altered rocks to establish eruption and subsidence histories
+ Mineral-specific insights into the magmatic systems and eruption dynamics of the Huckleberry Ridge Tuff and Lava Creek tuffs, Yellowstone
+ Integration of geophysical studies with records from eruption deposits to infer the current states of the magma systems below Taupo and Okataina volcanoes
+ A re-evaluation of the nature and timing of the Lava Creek Tuff eruption from Yellowstone volcano

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