Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand
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. O...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , |
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| Format: | Journal Article |
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Geological Society Publishing House
2018
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| Online Access: | http://hdl.handle.net/20.500.11937/70197 |
| _version_ | 1848762241052049408 |
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| author | Kirilova, M. Toy, V. Timms, Nicholas Eric Halfpenny, A. Menzies, C. Craw, D. Beyssac, O. Sutherland, R. Townend, J. Boulton, C. Carpenter, B. Cooper, A. Grieve, J. Little, T. Morales, L. Morgan, C. Mori, H. Sauer, K. Schleicher, A. Williams, J. Craw, L. |
| author_facet | Kirilova, M. Toy, V. Timms, Nicholas Eric Halfpenny, A. Menzies, C. Craw, D. Beyssac, O. Sutherland, R. Townend, J. Boulton, C. Carpenter, B. Cooper, A. Grieve, J. Little, T. Morales, L. Morgan, C. Mori, H. Sauer, K. Schleicher, A. Williams, J. Craw, L. |
| author_sort | Kirilova, M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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. |
| first_indexed | 2025-11-14T10:44:26Z |
| format | Journal Article |
| id | curtin-20.500.11937-70197 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:44:26Z |
| publishDate | 2018 |
| publisher | Geological Society Publishing House |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-701972019-01-08T07:44:53Z Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand Kirilova, M. Toy, V. Timms, Nicholas Eric Halfpenny, A. Menzies, C. Craw, D. Beyssac, O. Sutherland, R. Townend, J. Boulton, C. Carpenter, B. Cooper, A. Grieve, J. Little, T. Morales, L. Morgan, C. Mori, H. Sauer, K. Schleicher, A. Williams, J. Craw, L. 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. 2018 Journal Article http://hdl.handle.net/20.500.11937/70197 10.1144/SP453.13 Geological Society Publishing House restricted |
| spellingShingle | Kirilova, M. Toy, V. Timms, Nicholas Eric Halfpenny, A. Menzies, C. Craw, D. Beyssac, O. Sutherland, R. Townend, J. Boulton, C. Carpenter, B. Cooper, A. Grieve, J. Little, T. Morales, L. Morgan, C. Mori, H. Sauer, K. Schleicher, A. Williams, J. Craw, L. Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title | Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title_full | Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title_fullStr | Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title_full_unstemmed | Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title_short | Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand |
| title_sort | textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, alpine fault, new zealand |
| url | http://hdl.handle.net/20.500.11937/70197 |