Depth profile of frictional properties in the inner Nankai accretionary prism using cuttings from IODP Site C0002

Progress in Earth and Planetary Science

Riho Fujioka¹  Ikuo Katayama¹  Hanaya Okuda²  Manami Kitamura³  Takehiro Hirose⁴ 

[1] Department of Earth and Planetary Systems Science, Hiroshima University;Department of Ocean Floor Geoscience, Atmosphere and Ocean Research Institute, University of Tokyo;Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST);Kochi Institute for Core Sample Research (X-Star), Japan Agency for Marine Earth Science and Technology (JAMSTEC);

关键词: Nankai Trough;    Friction coefficient;    Velocity dependence of friction;    Clay minerals;    Accretionary prism;   

DOI  :  10.1186/s40645-022-00488-1

来源: DOAJ

【 摘 要 】

Abstract We conduct frictional experiments using cuttings collected at Nankai Trough IODP Site C0002 over 980.5–3262.5 mbsf (meters below seafloor) depth interval to better understand the frictional properties through the accretionary prism. The experiments are conducted at the in situ effective normal stresses (9–37 MPa) under brine-saturated conditions, and the slip velocity is abruptly changed in a stepwise manner to either of 0.3, 3, or 33 µm/s after the steady-state friction is reached. The friction coefficient (μ) of the cuttings samples ranges from 0.45 to 0.60, with a slight increase in μ with increasing depth, related to decreasing smectite content. The velocity dependence of friction (a − b) is positive at all depths and ranges from 0.001 to 0.006, which indicates a velocity-strengthening behavior; these values are consistent with relatively homogeneous deformation microstructures. The critical slip distance (D c) ranges from 0.5 to 123 μm, with relatively large values obtained for the smectite-rich samples. The changes in both the friction coefficient and rate- and state-friction parameters are likely associated with mineralogical change and consolidation with increasing depth. Although all of the cuttings samples collected from Site C0002 exhibit a velocity-strengthening behavior, a slight decreasing trend in a − b with increasing depth indicates either a nearly neutral velocity dependence or a possible transition to velocity-weakening behavior at greater depths, which may be attributed to the occurrence of slow earthquakes in the Nankai accretionary prism.

【 授权许可】

Unknown