loading page

Deep fault-controlled fluid flow driving shallow stratigraphically-constrained gas hydrate formation: Urutī Basin, Hikurangi Margin, New Zealand
  • +6
  • Andrew Robert Gorman,
  • Gareth J Crutchley,
  • Dylan R. Baker,
  • Douglas R.A. Fraser,
  • Stuart Henrys,
  • Anne M. Trehu,
  • Robert N. Harris,
  • Benjamin J. Phrampus,
  • Ingo Pecher
Andrew Robert Gorman
University of Otago

Corresponding Author:[email protected]

Author Profile
Gareth J Crutchley
GEOMAR - Helmholtz Centre for Ocean Research Kiel
Author Profile
Dylan R. Baker
University of Otago
Author Profile
Douglas R.A. Fraser
University of Otago
Author Profile
Stuart Henrys
GNS Science
Author Profile
Anne M. Trehu
COAS Oregon State University
Author Profile
Robert N. Harris
Oregon State University
Author Profile
Benjamin J. Phrampus
U.S. Naval Research Laboratory
Author Profile
Ingo Pecher
University of Auckland
Author Profile

Abstract

The Hikurangi Margin east of New Zealand’s North Island hosts an extensive gas hydrate province with numerous gas hydrate accumulations related to the faulted structure of the accretionary wedge. One such hydrate feature occurs in a small perched upper-slope basin known as Urutī Basin. We investigate this hydrate accumulation by combining a long-offset seismic line (10-km-long receiver array) with a grid of high-resolution seismic lines acquired with a 600-m-long hydrophone streamer. The long-offset data enable quantitative velocity analysis while the high-resolution data constrain the three-dimensional geometry of the hydrate accumulation. The sediments in Urutī Basin dip landward due to ongoing deformation of the accretionary wedge. These strata are clearly imaged in seismic data where they cross a distinct bottom simulating reflection (BSR) that dips, counterintuitively, in the opposite direction to the regional dip of the seafloor. BSR-derived heat flow estimates reveal a distinct heat flow anomaly that coincides spatially with the upper extent of a landward-verging thrust fault. We present a conceptual model of this gas hydrate system that highlights the roles of fault-controlled fluid flow at depth merging into strata-controlled fluid flow into the hydrate stability zone. The result is a layer-constrained accumulation of concentrated gas hydrate in the dipping strata. Our study provides new insight into the interplay between deep faulting, fluid flow and the shallow processes involved in gas hydrate formation.
20 Jul 2023Submitted to ESS Open Archive
20 Jul 2023Published in ESS Open Archive