Open AccessAsymmetric Brittle Deformation at the Pāpaku Fault, Hikurangi Subduction Margin, NZ, IODP Expedition 375
Author(s) -
Savage Heather M.,
Shreedharan Srisharan,
Fagereng Åke,
Morgan Julia K.,
Meneghini Francesca,
Wang Maomao,
McNamara David D.,
Wallace Laura M.,
Saffer Demian M.,
Barnes Philip M.,
Petronotis Katerina E.,
LeVay Leah J.
Publication year - 2021
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2021gc009662
Subject(s) - geology , subduction , fault (geology) , seismology , cataclastic rock , slip (aerodynamics) , seafloor spreading , petrology , tectonics , geophysics , physics , thermodynamics
Quantifying fault damage zones provides a window into stress distribution and rheology around faults. International Ocean Discovery Program (IODP) Expeditions 372/375 drilled an active thrust splay fault within the Hikurangi subduction margin. The fault, which is hosted in Pleistocene clastic sediments, is surrounded by brittle fractures and faults as well as ductile deformation features. We find that fracture density in the damage zone enveloping the fault is asymmetric, with the hanging wall showing greater overall fracture density and at greater distances from the fault than the footwall. Furthermore, the peak in fracture density occurs within an area of mesoscale folding and localized slip in the hanging wall rather than adjacent to the main fault zone. We attribute the asymmetry in damage to disparate deformation histories between the hanging wall and footwall, greater ductile deformation within the footwall, and/or dynamic stress asymmetry around a propagating rupture. Damage asymmetry is common at shallow depths in subduction zones and influences the mechanical and hydrological properties of the fault, such as channelized fluid flow and fault stability. Finally, we demonstrate that subduction zone faults show similar damage‐displacement scaling as continental faults.