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Physical properties and gas hydrate at a near-seafloor thrust fault, Hikurangi Margin, New Zealand
  • +12
  • Ann Elizabeth Cook,
  • Matteo Paganoni,
  • Michael Benedict Clennell,
  • David Daniel McNamara,
  • Michael Nole,
  • Xiujuan Wang,
  • Shuoshuo Han,
  • Rebecca Bell,
  • Evan A Solomon,
  • Demian M Saffer,
  • Philip Barnes,
  • Ingo Pecher,
  • Laura Wallace,
  • Leah J. LeVay,
  • Katerina Petronotis
Ann Elizabeth Cook
Ohio State University

Corresponding Author:[email protected]

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Matteo Paganoni
Shell International Global Solutions B.V.
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Michael Benedict Clennell
CSRIO
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David Daniel McNamara
University of Liverpool
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Michael Nole
Sandia National Lab
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Xiujuan Wang
Institute of Oceanology,Chinese Academy of Sciences;Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology
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Shuoshuo Han
University of Texas Institute for Geophysics
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Rebecca Bell
Imperial College London
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Evan A Solomon
University of Washington
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Demian M Saffer
University of Texas at Austin
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Philip Barnes
National Institute of Water & Atmospheric Research
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Ingo Pecher
University of Auckland
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Laura Wallace
GNS Science
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Leah J. LeVay
International Ocean Discovery Program, Texas A&M University
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Katerina Petronotis
Texas A&M University
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Abstract

The Pāpaku fault zone, drilled at IODP Site U1518, is an active splay fault in the frontal accretionary wedge of the Hikurangi Margin. In logging-while-drilling data, the 33 m-thick fault zone exhibits mixed modes of deformation associated with a trend of downward decreasing density, P-wave velocity and resistivity. Methane hydrate are observed from ~30-585 mbsf, including within and surrounding the fault zone. Hydrate accumulations are vertically discontinuous and occur throughout the entire logged section at low to moderate saturation in silty and sandy cm-thick layers. We argue that the hydrate distribution implies that the methane is not sourced from fluid flow along the fault but instead by local diffusion. This, combined with geophysical observations and geochemical measurements from Site U1518, suggests that the fault is not a focused migration pathway for deeply-sourced fluids and that the near-seafloor Pāpaku fault zone has little to no active fluid flow.
28 Aug 2020Published in Geophysical Research Letters volume 47 issue 16. 10.1029/2020GL088474