Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand

Virginia Gail Toy*, Rupert Sutherland, John Townend, Michael John Allen, Leeza Becroft, Austin Boles, Carolyn Boulton, Brett M. Carpenter, Alan Cooper, Simon C. Cox, Christopher Daube, Daniel R. Faulkner, Angela Halfpenny, Naoki Kato, Stephen Keys, Martina Kirilova, Yusuke Kometani, Timothy Little, Elisabetta Mariani, Benjamin MeloshCatriona D. Menzies, Luiz Morales, Chance Morgan, Hiroshi Mori, André Niemeijer, Richard Norris, David J. Prior, Katrina Sauer, Anja M. Schleicher, Norio Shigematsu, Damon A H Teagle, Harold Tobin, Robert Valdez, Jack Williams, Samantha Yeo, Laura May Baratin, Nicolas Barth, Adrian Benson, Carolin Boese, Bernard Célérier, Calum J. Chamberlain, Ronald Conze, Jamie Coussens, Lisa Craw, Mai Linh Doan, Jennifer Eccles, Jason Grieve, Julia Grochowski, Anton Gulley, Jamie Howarth, DFDP-2 Science Team

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5–893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite Terrane-derived schists, protomylonites and mylonites, terminating 200–400 m above an Alpine Fault Principal Slip Zone (PSZ) with a maximum dip of 62°. The most diagnostic structural features of increasing PSZ proximity were the occurrence of shear bands and reduction in mean quartz grain sizes. A change in composition to greater mica:quartz + feldspar, most markedly below c. 700 m MD, is inferred to result from either heterogeneous sampling or a change in lithology related to alteration. Major oxide variations suggest the fault-proximal Alpine Fault alteration zone, as previously defined in DFDP-1 core, was not sampled.

Original languageEnglish
Pages (from-to)497-518
Number of pages22
JournalNew Zealand Journal of Geology and Geophysics
Issue number4
Publication statusPublished - 17 Oct 2017


  • Alpine Fault
  • cataclasite
  • mylonite
  • New Zealand
  • scientific drilling


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