PhD topic: Glaciovolcanism in Tongariro National Park, North Island, New Zealand
Email: colro756[at] student.otago.ac.nz
New and on-going geological mapping of Tongariro and Ruapehu volcanoes, along with dating of lava flows and moraines has revealed effusive volcanic activity occurring synchronously with periods of glaciation. Steep, over-thickened, ridge-capping lava flows contain fracture patterns indicative of cooling by an external fluid, and suggest impoundment of the lavas by valley-filling glaciers over the last 50 ka (Conway et al., 2015). These authors have provided a complete reinterpretation of the evolution of these volcanoes which forms the basis of the present study, and a working hypothesis that ice periodically capped the volcanic cones. The primary aim of this project is to establish the physical, subglacial processes occurring at both of these volcanoes. This will be achieved by characterising the proximal deposits formed and determining their eruptive and emplacement processes. Initial fieldwork resulted in a maps, stratigraphic logs and samples of previously undescribed hyaloclastite tuffs and breccias bearing fluidal and glassy clasts and bombs, intercalated with lavas and intrusions around the central core of Tongariro Peak (South Crater) and on the eastern flanks of Ruapehu (Middle Whangaehu) (Fig. 1A-B). The most striking thing about these deposits is that they indicate the presence of abundant water accumulation at the apparent summit of these volcanoes. It is hypothesised that this took the form of trapped glacial lakes. Further investigation will be carried out into the thermodynamics behind andesite lava-ice interaction and the formation of cooling joints in a glaciovolcanic setting, using Ruapehu lavas (Fig. 1C-D) as an example.
Figure 1: A: Waterlain lapilli tuff flow deposit, South Crater, Tongariro; B: Jigsaw-fit fracturing in hyaloclastite, Middle Whangaehu, Ruapehu; C: Esker-type lava flow, Middle Whangaehu, Ruapehu; D: Columnar-jointed lava flow, Turoa Skifield, Ruapehu.
The aims of this project are:
- to provide a glaciovolcanic evolution model for Tongariro, particularly focussing on the eruption and emplacement processes of individual proximal deposits;
- to determine the boundary conditions prior to glaciovolcanic evolution, particularly ice thickness and extent and pre-existing topography, with implications for the paleoclimate of the North Island
- to characterise and determine emplacement mechanisms for volcaniclastic deposits associated with glaciovolcanic eruptions on Ruapehu.
- to carry out a detailed investigation of the physical mechanisms associated with the production, emplacement and deformation of andesitic eruptives in the subglacial environment
- to investigate the thermodynamics associated with the interaction of an andesitic lava flow, dammed behind a glacier.
Previous work on subglacial volcanoes has been largely confined to basaltic or rhyolitic centres such as Iceland, North America and Antarctica (eg. Smellie and Skilling, 1994; Gudmundsson et al., 1997; Edwards et al., 2002). Relatively few studies have focussed on the interaction of intermediate volcanism with ice (Stevenson et al., 2009), and even fewer have documented fragmental deposits (Lachowycz et al., 2015). Therefore, the volcanoes of the TNP provide an ideal case study for subglacial processes in an andesitic setting. Conway et al. (2015) realised the significance of unusual joint patterns on Ruapehu lava flows and related them to episodes of glaciation, but an in-depth study of this interaction is needed as none currently exist for New Zealand volcanoes. Volcanic eruptions beneath or proximal to ice give rise to additional hazards beyond those associated with subaerial eruptions. Accumulation and release of meltwater can cause catastrophic flooding, debris flows and lahars, or external water may cause lava to erupt explosively (Smellie and Edwards, 2016). Investigation into the thermodynamics behind the interaction, as well as the cooling behaviour of Ruapehu lavas may contribute to our understanding of glaciovolcanic interactions at other andesitic centres worldwide. This study will also extend our knowledge of the behaviour of these iconic volcanoes which will aid in hazard planning and mitigation, essential for some of the most popular and economically important walking tracks and ski areas in the country. In addition, it will provide further constraints on the extent and thickness of ice capping these volcanoes, and therefore an indication of paleoclimate in this region (Conway et al., 2015).
MSci Geosciences (Hons) 2015: Durham University (UK)
Thesis: Nature and significance of pyroclastic deposits from 29th December 2013 San Miguel eruption, El Salvador, Supervised by: Dr R.J. Brown
Key skills and research interests
- Field geology
- Physical volcanology
- Volcanic sedimentology
- Glaciovolcanism and water-magma interaction
- Experimental volcanology
2016: Wellman Research Award, GSNZ
2017: GSNZ Young Researcher Travel Award
- Cole, R.P., White, J.D.L., Leonard, G.S., Townsend, D.B., 2016, How volcanism and glaciations shaped South Crater, Tongariro Volcano, New Zealand, GSNZ Wanaka, NZ
- Brown, R.J., Hernandez, W., Cole, R.P., 2015, The 29th December 2013 eruption of San Miguel Volcano, El Salvador, VMSG Norwich, UK
- IAVCEI Student Member, 2016-present
- International Association of Sedimentologists Student Member, 2016-present
- Geological Society of New Zealand, 2016-present
- New Zealand Federation of Graduate Women, 2016-present
- Otago Volcanology Group
- Conway, C.E., Townsend, D.B., Leonard, G.S., Wilson, C.J.N., Calvert, A.T., Gamble, J.A., 2015, Lava-ice interaction on a large composite volcano: a case study from Ruapehu, New Zealand, Bulletin of Volcanology, 77:21
- Edwards, B.R., Russell, J.K., Anderson, R.G., 2002, Subglacial, phonolitic volcanism at Hoodoo Mountain volcano, northern Canadian Cordillera, Bulletin of Volcanology, 64, 254-272
- Gudmundsson, M.T., Sigmundsson, F., Björnsson, H., 1997, Ice-volcano interaction of the 1996 Gjálp subglacial eruption, Vatnajökull, Iceland, Nature, 389, 954-957
- Lachowycz, S.M., Pyle, D.M., Gilbert, J.S., Mather, T.A., Mee, K., Naranjo, J.A., Hobbs, L.K., 2006, Glaciovolcanism at Volcán Sollipulli, southern Chile: Lithofacies analysis and interpretation, Journal of Volcanology and Geothermal Research, 303, 59-78
- Smellie, J.L., Skilling, I.P., 1994, Products of subglacial volcanic eruptions under different ice thicknesses: two examples from Antarctica, Sedimentary Geology, 91, 115-129
- Smellie, J.L., Edwards, B.R., 2016, Glaciovolcanism on Earth and Mars: Products, Processes and Palaeoenvironmental Significance, Cambridge University Press, United Kingdom, pp 460