Extreme Hydrothermal Conditions Near an Active Geological Fault, DFDP-2B Borehole, Alpine Fault, New Zealand

Monday, 14 December 2015: 08:30
306 (Moscone South)
Rupert Sutherland1, John Townend2, Virginia Toy3, Michael Allen4, Laura-May Baratin5, Nicolas C Barth6, Leeza Beacroft3, Adrian Benson5, Carolin Morag Boese7, Austin Boles8, Carolyn J Boulton9, Lucie Capova5, Brett M Carpenter10, Bernard P Celerier11, Calum John Chamberlain12, Ronald Conze13, Alan Cooper3, Jamie Coussens14, Ashley Coutts15, Simon Cox1, Lisa Craw3, Mai-Linh Doan16, Jennifer Dawn Eccles17, Daniel Roy Faulkner4, Jason Grieve3, Julia Grochowski5, Anton Gulley15, Gilles Henry18, Jamie D Howarth1, Katrina M Jacobs5, Tamara Jeppson19, Naoki Kato20, Stephen Keys5, Martina Kirilova3, Yosuke Kometani21, Adrienn Lukács22, Robert Langridge23, Weiren Lin24, Timothy Little25, Deirdre Mallyon26, Elisabetta Mariani4, Ray Marx3, Cecile Massiot5, Loren Mathewson22, Ben Melosh27, Catriona Dorothy Menzies14, Jo Moore28, Luiz F. G. Morales29, Chance Morgan10, Hiroshi Mori30, Andre R Niemeijer31, Osamu Nishikawa32, Olivier Nitsch11, Jehanne Paris Cavailhes11, Brent Pooley22, David John Prior33, Alex Pyne34, Katrina M Sauer3, Martha K Savage5, Anja Schleicher35, Douglas R Schmitt36, Norio Shigematsu30, Sam Taylor-Offord25, Harold J Tobin19, Phaedra Upton1, Robert D Valdez37, Konrad Weaver25, Thomas Wiersberg13, Jack Nicholas Williams3, Sam Yeo22, Martin Zimmer38 and Neil Broderick17, (1)GNS Science-Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand, (2)Victoria University of Wellington, School of Geography, Environment, and Earth Sciences,, Wellington, New Zealand, (3)University of Otago, Dunedin, New Zealand, (4)University of Liverpool, Liverpool, United Kingdom, (5)Victoria University of Wellington, Wellington, New Zealand, (6)University of California Riverside, Riverside, CA, United States, (7)Organization Not Listed, Washington, DC, United States, (8)University of Michigan, Earth and Environmental Sciences, Ann Arbor, MI, United States, (9)University of Liverpool, Earth, Ocean and Ecological Sciences, Liverpool, United Kingdom, (10)University of Oklahoma Norman Campus, Norman, OK, United States, (11)University of Montpellier II, Montpellier Cedex 05, France, (12)Victoria University of Wellington, School of Geography, Environment, and Earth Sciences, Wellington, New Zealand, (13)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, (14)University of Southampton, Southampton, United Kingdom, (15)University of Auckland, Auckland, New Zealand, (16)ISTerre Institute of Earth Sciences, Saint Martin d'Hères, France, (17)The University of Auckland, Auckland, New Zealand, (18)Géosciences Montpellier, Montpellier Cedex 05, France, (19)University of Wisconsin Madison, Madison, WI, United States, (20)Osaka University, Osaka, Japan, (21)Yamaguchi University, Yamaguchi, Japan, (22)University of Otago, Department of Geology, Dunedin, New Zealand, (23)GNS Science, Lower Hutt, New Zealand, (24)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (25)Victoria University of Wellington, School of Geography, Environment and Earth Sciences, Wellington, New Zealand, (26)University of Alberta, Edmonton, AB, Canada, (27)McGill University, Montreal, QC, Canada, (28)Macquarie University, Sydney, Australia, (29)Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany, (30)Geological Survey of Japan, Tsukuba Ibaraki, Japan, (31)Utrecht University, Department of Earth Sciences, Utrecht, Netherlands, (32)Akita University, Akita, Japan, (33)University of Otago, Geology, Dunedin, New Zealand, (34)Victoria University of Wellington, Antarctic Research Centre, Wellington, New Zealand, (35)Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany, (36)University of Alberta, Physics, Edmonton, AB, Canada, (37)Pennsylvania State University, University Park, PA, United States, (38)GFZ Potsdam, Potsdam, Germany
The DFDP-2B borehole sampled rocks above and within the upper part of the Alpine Fault, New Zealand, to a depth of 893 m in late 2014. The experiment was the first to drill a major geological fault zone that is active and late in its earthquake cycle. We determined ambient fluid pressures 8-10% above hydrostatic and a geothermal gradient of 130-150 °C/km in rocks above the fault. These unusual ambient conditions can be explained by a combination of: rock advection that transports heat from depth by uplift and oblique slip on the fault; and fluid advection through fractured rock, driven by topographic forcing, which concentrates heat and causes fluid over-pressure in the valley. Highly-anomalous ambient conditions can exist in the vicinity of active faults, and earthquake and mineralization processes occur within these zones.