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Fingerprinting geothermal fluids: Tracking the magmatic signature

2013-2016
Funding: Royal Society of New Zealand
Fund: Marsden Fund – Fast Start
Contact: Dr. Isabelle Chambefort
Collaborators: Prof. John Dilles (Oregon State University); Prof. Chris Heinrich (ETH-Zurich).

This research project aims to use both established and pioneering analytical techniques to track the magmatic fluid signature in geothermal systems by characterising its fingerprint.

This world-first approach to active geothermal systems will influence conceptual models of the evolution of magmatism and the magmatic-hydrothermal transition beneath the Taupo Volcanic Zone (TVZ), and enhance the understanding of the magmatic heat source influence on geothermal systems.

conceptual model of geothermal fluid convection cell

Conceptual model of geothermal fluid convection cell

Objective 1: Characterisation of the magmatic fingerprint

Aim: provide insight into the composition of the magmatic fluid when it exsolves from a magma body.

Chemical characterisation (fingerprinting) of the magmatic fluids that participate in the geothermal fluid convection cell will allow us to:

  • create a chemical model of the magmatic fluid derived from intermediate and/or felsic magma composition;
  • reconstruct the pattern of alteration zonation associated with the magmatic-hydrothermal transition by analysing hydrothermal alteration minerals; and
  • recognise the key tracer chemical elements that can be directly linked to degassing magmas.
Fluid inclusion

Fluid Inclusion

Objective 2: Tracking the magmatic fluid signature in geothermal systems

Aim: characterise the magmatic influence in TVZ geothermal systems.

The chemical variations of the fluids and minerals from Objective 1 will be used as a comparison for the analysis of hydrothermal alteration minerals and fluids in selected geothermal fields and will aim to:

  • characterise the variations in trace elements in hydrothermal alteration minerals;
  • give insight on deep water-rock interaction processes and temporal variation of the geothermal system; and
  • identify deep magmatic degassing at depth in dilute geothermal systems.

Recent Publications

Lewis, B., Chambefort, I., Rae, A., Bignall, G., Ganefianto, N., submitted 2014, Ngatamariki: the porphyry-epithermal transition in the Taupo Volcanic Zone, New Zealand. Submitted to Economic Geology on 19.02.2014.

Begue, F., Gravley, D., Chambefort, I., Deering, C., and Kennedy, B., 2014, Magmatic volatile distribution as recorded by rhyolitic melt inclusions in the Taupo Volcanic Zone, New Zealand, in press.

Chambefort, I., Lewis, B., Wilson, C.J.N., Rae, A.J., Bignall, G., Coutts, C. and Ireland, T.R., 2014. Stratigraphy and structure of the Ngatamariki geothermal system: New U-Pb geochronology and its implications for Taupo Volcanic Zone evolution, Journal of Volcanology and Geothermal Research, V274, 51-70.