Geoscience Society of New Zealand President's Lecture Event as iCalendar

17 May 2016

1pm

Venue: HSB 201N-370

Location: 10 Symonds St

Dr Adrian Pittari from the University of Waikato will present this talk about Ignimbrite - ‘rock’ of the central North Island and the global volcanic phenomenon of pyroclastic flows

In the 1930s New Zealand geologist Patrick Marshall coined the term ‘ignimbrite’ for many of the vitric tuffs across the central North Island and Coromandel landscape and likened their origin to the ‘sand flows’ of Katmai or nuées ardentes of Mt. Pelé.  Ignimbrites are now recognised on all continents as the sheet-like, pumiceous deposits of pyroclastic flows.  As a geological resource, ignimbrites have played an important role in the development of civilisation, particularly ancient Rome, and elsewhere across the Mediterranean.  Today they are still a useful resource, particularly as a building stone, including in the Waikato.  As a geological hazard, ignimbrites represent the deadliest and most destructive volcanic phenomena and their presence in the central North Island allude to the worst-case threat from the rhyolitic caldera eruptions of the Taupo Volcanic Zone.

Variations in the internal deposit characteristics reveal complexities in the physical processes of pyroclastic flows as they travel over topography and rapidly accumulate.  Evidence for key physical parameters, particularly dynamic pressure and temperature, can be inferred from diagnostic features within ignimbrites.  This talk will review the variation in physical characteristics within and between different ignimbrites, including findings revealed in ignimbrites from the Las Cañadas caldera on Tenerife, the Colli Albani volcano near Rome and the Pliocene Waihi and early Pleistocene Mangakino calderas in New Zealand. 

Biography: Adrian Pittari is a senior lecturer in volcanology at the University of Waikato, and has lived in New Zealand since 2007. An Australian by birth, with volcanic Aeolian Island (Italian) heritage, he grew up on the alluvial plains above the boundary of the Cretaceous Gippsland Basin and the Palaeozoic Lachlan Fold Belt, Victoria.  He has a BSc(Hons) in Earth sciences from the University of Melbourne and a PhD in volcanology from Monash University.  Before arriving in New Zealand he studied volcanic processes associated with an ignimbrite on Tenerife (PhD) and kimberlites in Saskatchewan, Canada (postdoc.).    Recent research in New Zealand has involved unravelling the volcanic processes within ignimbrites of the Coromandel and early Taupo volcanic zones, monogenetic volcanism of the South Auckland Volcanic Field and eruption styles at young vents on the Tongariro Volcanic Centre.