This is a past event
Please join us for a research seminar presented by Dr Catriona Menzies on 'The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand'.
The seminar will take place from 1-2 PM on Thursday, 18th October in Lecture Theatre 2 of the Meston Building. All are welcome to attend.
Abstract:
Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here Dr Menzies uses geochemical tracers of fluid–rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific-Australian plate boundary through South Island, New Zealand. The fault is late in its seismic cycle and fails in regular (~300 years) large earthquakes (Mw ~8) with the most recent event in 1717 AD. This provides a rare opportunity to document processes in a continental-scale fault zone that ruptures in major seismic events. Significant convergent motion has formed the Southern Alps (>3000 m peaks) and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Fault rocks are chemically altered from successive episodes of fluid-rock interaction, which influences fault strength, permeability evolution, and therefore the fault’s mechanical behaviour.
Here Dr Menzies will summarise the recent work of the Deep Fault Drilling Project into the Alpine Fault. She will then go on to use geochemical data to answer key questions relating to the role of fluids in fault zone processes. Using geochemical tracers of fluid-rock exchange (87Sr/86Sr, δD, δ18O, δ13C, 3He/4He) she determines fluid origins, flow paths and budgets on the Alpine Fault. Meteoric waters are primarily responsible for modifying fault zone permeability during fluid–rock interactions and may facilitate the generation of high pore fluid pressures that could assist episodic earthquake rupture.
- Speaker
- Dr Catriona Menzies
- Venue
- Meston Lecture Theatre 2