Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand

Martina Kirilova, Virginia G. Toy, Nick Timms, Angela Halfpenny, Catriona Dorothy Menzies, Dave Craw, Olivier Beyssac, Rupert Sutherland, John Townend, Carolyn Boulton, Brett M. Carpenter, Alan Cooper, Jason Grieve, Timothy Little, Luiz Morales, Chance Morgan, Hiroshi Mori, Katrina Sauer, Anja M. Schleicher, Jack WilliamsLisa Craw

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
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Graphitization in fault zones is associated both with fault weakening and orogenic gold mineralization. We examine processes of graphitic carbon emplacement and deformation in the active Alpine Fault Zone, New Zealand by analysing samples obtained from Deep Fault Drilling Project (DFDP) boreholes. Optical and scanning electron microscopy reveal a microtextural record of graphite mobilization as a function of temperature and ductile then brittle shear strain. Raman spectroscopy allowed interpretation of the degree of graphite crystallinity, which reflects both thermal and mechanical processes. In the amphibolite-facies Alpine Schist, highly crystalline graphite, indicating peak metamorphic temperatures up to 640°C, occurs mainly on grain boundaries within quartzo-feldspathic domains. The subsequent mylonitization process resulted in the reworking of graphite under lower temperature conditions (500–600°C), resulting in clustered (in protomylonites) and foliation-aligned graphite (in mylonites). In cataclasites, derived from the mylonitized schists, graphite is most abundant (<50% as opposed to <10% elsewhere), and has two different habits: inherited mylonitic graphite and less mature patches of potentially hydrothermal graphitic carbon. Tectonic–hydrothermal fluid flow was probably important in graphite deposition throughout the examined rock sequences. The increasing abundance of graphite towards the fault zone core may be a significant source of strain localization, allowing fault weakening.
Original languageEnglish
Pages (from-to)205-233
Number of pages29
JournalGeological Society Special Publications
Early online date15 Nov 2017
Publication statusPublished - 2018

Bibliographical note

Raman spectra of graphite from the Alpine Fault rocks is available at

We gratefully acknowledge the contribution of all members
of DFDP-1 and DFDP-2 Science Teams, as described
in GNS Science Report 2011/48 and GNS Science Report
2015/50. DFDP drilling projects were funded by: the
International Continental Scientific Drilling Program
(ICDP); GNS Science; Victoria University of Wellington;
the University of Otago; the University of Auckland; the
University of Canterbury; Deutsche Forschungsgemeinschaft;
the University of Bremen; the University of Liverpool;
the Marsden Fund of the Royal Society of New
Zealand; New Zealand Ministry for Business Innovation
and Employment; and Natural Environment Research
Council (NERC) grants. The current research was funded
by the University of Otago. The authors acknowledge the
use of Curtin University’s Microscopy & Microanalysis
Facility, whose instrumentation has been partially funded
by the University, State and Commonwealth Governments
of Australia. We also wish to thank our colleague Olivier
Beyssac for generously offering use of Raman microspectrometer
laboratory facilities at IMPMC, Paris, France, and
for valuable discussions and helpful comments during the
acquisition, processing and interpretation of Raman data.

From: Gessner, K., Blenkinsop, T. G. & Sorjonen-Ward, P. (eds) Characterization of Ore-Forming Systems from Geological, Geochemical and Geophysical Studies. Geological Society, London,


  • graphite
  • hydrothermal
  • tectonic
  • fault
  • cataclasite
  • Raman
  • Alpine Fault
  • Deep Fault Drilling Project (DFDP)


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