International Joint Workshop on
Slow-to-Fast Earthquakes 2025

Pre-meeting Field Trip (September. 23)

Tectonic Structures and Fluid–Rock Interactions along shallow subduction plate interfaces in the Cretaceous Shimanto Accretionary Complex

浅部沈み込みプレート境界の変形構造と岩石―流体相互作用：白亜系四万十付加体

Field Trip Overview

This field excursion focuses on the deformation structures within the Shimanto Belt, an exhumed accretionary complex in southwest Japan (150-250 ˚C for the maximum paleo-temperature). Participants will examine outcrops that preserve a range of tectonic features in tectonic mélange units, which provide insights into the stress regime, deformation mechanisms, and fluid activity during subduction-related tectonics. The excursion aims to integrate multiple lines of geological evidence, including structural analysis, pressure–temperature estimates, geochemical signatures, and rock magnetic data, to discuss the dynamic processes operating within accretionary prisms. Emphasis will be placed on interpreting the spatial and temporal evolution of stress, the role of fluids in deformation, and how these processes are recorded in the rock.