Central Otago rocks reveal earth’s secrets
Central Otago rocks are helping Australian geologists understand how the earth has developed through time and how it might continue to develop.
Monash University scholars Casey Blundell and Mitchell O’Mara are conducting field research around the Millers Flat, Alexandra and Danseys Pass areas, as well as other parts of central Otago, as part of Blundell’s PhD looking at the structural and tectonic evolution of the Otago region.
Blundell said she had a particular interest in the role of the Alpine Fault – a major plate boundary between Australia and New Zealand.
‘‘There is a lot of (geospatial) data available for the Otago area that deserves detailed study. There have been few complete interpretations and not much is known about what this data actually means. The area has a complicated history to unravel.’’
Part of her research uses the magnetic properties of the rocks to create a geologic map, and is important for understanding the three-dimensional structure of the earth, she said.
‘‘This has implications for understanding how Otago and the Earth has developed through geologic time and how they might continue to develop. The evolution of folds or faults you can see in rocks around here, influenced by pressures as far away as the Alpine Fault – how movement along that fault is distributed down through into Otago is what I am interested in.
‘‘By observing how the folds are moving and developing here, we can begin to understand how everything has to move a little bit in order for a big structure to move a lot.
‘‘I want to understand what massive deformation (>800km) along a plate boundary affects the structures here, and what that looks like in 3D.’’
Their research would help multiple people, and has implications for the likes of mineral and environment industries, she said.
‘‘Mapping the network of faults and structures of the schist might tell us what possible pathways fluids have migrating through the crust.
‘‘Fluids can carry and deposit many things like gold and tungsten in this part of the world, and in Australia fluids can carry copper, gold and iron oxides that are used in many everyday products.
‘‘This sort of information can be used in a many different ways – at a big scale to understand how the earth and continents developed, and at smaller scales how rocks are locally deformed and what this means for the lay of the land.’’
Geologists Casey Blundell and Mitchell O’Mara.