Frictional behavior of carbonate-rich gouge from the Hikurangi subduction margin

Otis Wickenhaeuser, & Heather M. Savage

Submitted September 7, 2025, SCEC Contribution #14717, 2025 SCEC Annual Meeting Poster #TBD

The Hikurangi Subduction Margin accommodates plate motion through a range of fault slip behaviors, including frequent and recurring slow slip events (SSEs) as well as large megathrust earthquakes. The frictional properties of the incoming sediments, particularly carbonate-rich materials, may play a key role in controlling these slip behaviors.
Here we present laboratory friction experiments on natural carbonate-bearing input sediments from the Hikurangi Margin to investigate how temperature and pressure influence frictional velocity dependence and time-dependent healing. Using a triaxial deformation apparatus, we performed velocity steps (0.05–10 µm/s) and slide-hold-slide tests (10–10⁴ s holds) at confining pressures of 22–250 MPa, pore pressures of 2–100 MPa, and temperatures of 22–100 °C. These conditions were selected to replicate the in situ P–T conditions at depth along the Hikurangi subduction interface.
Prior to shearing, each experiment was held at the target pressure and temperature conditions for three hours to allow the pore fluid to fully saturate with dissolved sample material. This equilibration time was determined experimentally via compaction rate change and thin section analysis, which show that dissolution rates slow considerably after ~2.5 hours under constant P–T conditions. This step ensures that mechanical measurements reflect steady-state chemical and physical conditions, minimizing variability between runs.
Post-experiment microstructural analyses revealed deformation mechanisms including calcite twinning, pressure solution, and cataclasis. By combining mechanical data with microstructural observations, we link frictional behavior to grain-scale deformation processes specific to Hikurangi sediments. These results improve our understanding of how lithology influences the timing and stability of slip along the Hikurangi Margin and provide critical constraints for models of megathrust behavior in this tectonic setting.

Key Words
friction, rock mechanics, subduction zone, microstructures, carbonate, temperature

Citation
Wickenhaeuser, O., & Savage, H. M. (2025, 09). Frictional behavior of carbonate-rich gouge from the Hikurangi subduction margin. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)