Giulia Airoldi
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PhD postgraduateBSc, MSc: Dipartimento di Scienze della Terra, Facoltà di Torino (IT) PhD subject:Magma transport and propagation of Ferrar Dolerite intrusive sheets at Allan Hills, Terracotta Mountain and Solitary Rocks, Antarctica. Supervisor: James White Co-advisors: Alan Cooper Dr. Elena Zanella, Dipartimento di Scienze della Terra, Università di Torino (IT) (co-advisor) Email: g.airoldi.a@gmail.com |
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Fig 1. Areas visited along the Transantarctic Mtns for field-mapping and rock-sample collection |
Aim:
The aim of my research is to understand the evolution of the Jurassic Ferrar Large Igneous Province of Antarctica. In order to do so and reconstruct the geometry of the Ferrar plumbing system, I study (a) the distribution of Ferrar Dolerite sills and dikes across the Transantarctic Mtns, field relationships and compositional/physical properties of the dolerite forming the intrusions.
Fig 2. Aerial photo of Pandora Spire and Solitary Rocks (right, foreground) and Terracotta Mtn (centre-left, background) |
Methods:
- Field mapping
- Photogeology
- Rock Magnetism (temperature-dependent magnetic susceptibility (Km/T) isothermal remanent magnetization (IRM); anisotropy of magnetic susceptibility (AMS); anisotropy of the isothermal remanent magnetization (AIRM).
- Petrography, petrofabric and geochemistry.
Fig 3. Network of sills S of Terracotta Mountain |
Overview:
The onset of Mid-Jurassic continental flood basalt volcanism in Africa, South America and Antarctica marked the breakup of the Gondwana Supercontinent.
In Antarctica tholeiitic magmas erupted and emplaced in less than 1 million years, produced the Ferrar Large Igneous Province, now exposed throughout Australia, New Zealand and Antarctica in one of the most extensive continental flood-basalt provinces on Earth (>2.3*105 km3). In Antarctica alone the province can be observed for over 3,500 km, from the Theron Mountains to Horn Bluff. Extrusive Mawson volcaniclastic deposits and Kirkpatrick Basalt represent the ruins of phreatomagmatic vents and lava flows developed at the surface; intrusive rocks consist of the Dufek layered mafic intrusion and sills and dikes of the Ferrar Dolerite. Dolerite sills and dikes intruded pre-Cambrian basement rocks and a Devonian-to-Jurassic sedimentary sequence (Beacon Supergroup).
Fig 4. Zigzag dike at Allan Hills. |
A vertical ‘traverse’ of the plumbing system was conducted by field study at Solitary Rocks and Terracotta Mtn., in the Ferrar Glacier-Taylor Valley region, and Allan Hills, in South Victoria Land. At Solitary Rocks (originally ~3-2.5km depth) sills up to ~350m thick travelled laterally throughout the granitic basement. At Terracotta Mtn irregular dikes delivered magma from lower sills into sub-horizontal paths situated at shallower stratigraphic levels. At Allan Hills’ the intrusive network reflects a process of intrusion dominated by magma overpressure, local stresses between interacting dikes, and vertical variations of host rock mechanical properties. Interconnections of dolerite sills with inclined sheets are the result of this process, and represent the preferred mode of magma transport, at least in the shallowest portions of the Ferrar plumbing system.
Funds:
Antarctica New Zealand; Helicopters New Zealand; Division of Science Postgraduate Students Grant; Otago University Research Grant 2007/09; Antarctic Science bursary (2007); Polar Environment study group, Otago.
Publications:
Journal articles
Airoldi G., Muirhead J., White J.D.L., Rowland J. (2011): “Emplacement of magma at shallow depth and development of local vents: insights from field relationships at Allan Hills (South Victoria Land, East Antarctica)” – Antarctic Science, doi:10.1017/S0954102011000095.
Theses
2010 PhD – "Magma injection dynamics in the shallow Ferrar LIP (South Victoria Land, Antarctica)".
2005 MSc – "Magnetic study applied to pyroclastic rocks: flow directions and emplacement mechanisms of the lower Brown Tuffs (Vulcano, Aeolian Islands)" (in Italian).
2003 BSc – "The ‘Colle delle Porte’ quarry at the watershed between Po and Pellice valleys (Dora Maira Massif): field data and petrographic analysis" (in Italian).
Conference Abstracts and co-authored works:
Muirhead J.D., Airoldi G., Rowland J.V., White J.D.L. (in review, GSA Bulletin): “Origins of sheet intrusions in the shallow plumbing system of the Ferrar Large Igneous Province: Insights from Allan Hills and Terra Cotta Mountain, Antarctica”.
Cicchino A., Zanella E., De Astis G., Lanza R., Lucchi F., Airoldi G., Mana S. (submitted, JVGR): “Rock-magnetism and compositional investigation of Brown Tuffs deposits at Lipari and Vulcano (Aeolian Islands – Italy)”.
Airoldi G., Muirhead J., White J.D.L., Rowland J. (2008): Intrusion of magma into a heterogeneous media: an example from field observations at Terracotta Mtn (Antarctica). Article abstract presented at IAVCEI G.A. 2008 (Reykjavik, Iceland).
Airoldi G., Muirhead J., White J.D.L., Rowland J. (2008): Two-stage intrusion history of a Ferrar Dolerite shallow intrusive complex at Allan Hills (Ferrar Large Igneous Province), Antarctica. Abstract presented at IAVCEI G.A. 2008 (Reykjavik, Iceland).
Airoldi G. and White J.D.L. (2008): Traverse of the Ferrar Large Igneous Province of Antarctica: from ~3.5 km depth to the surface. Extended abstract - LASI III (Elba Island, Italy).
Airoldi G., White J.D.L., Rowland J., Muirhead J. (2007): Field characteristics of dykes in the Allan Hills and their implications for magma emplacement, Ferrar Large Igneous Province, Antarctica. Abstract presented at XXIV IUGG 2007 (Perugia, Italy).
Lanfranco M., Olivotti M., Airoldi G. (2005): “Hydraulic maintenance of Erro Torrent: a pilot project for sediment management of local competence water streams”. Poster presented at “ MAEGS 14th”, Torino, September 2005.