Muthre, Mishelle; Naruse, Hajime; Proust, Jean-Noël; Pizer, Charlotte; Huang, Jyh-Jaan Steven; Ikehara, Ken; Strasser, Michael (2026): Grain-size distribution of from different Holes of IODP Expedition 386 [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.988692 (DOI registration in progress)

This dataset provides grain-size distributions for 278 sediment samples from 11 sediment cores targeting four event beds - Event Bed 1 (CE 2011 Tohoku-Oki), Event Bed 2 (CE 1456 Kyōtoku), Event Bed 3 (CE 869 Jogan), and Event Bed 4 (2.3 ka) - as well as intervening deposits (other event beds and hemipelagic background sediment) from four sites in three trench basins: Basins S3 (site M0091), C1 (site M0090), and C2 (sites M0089 and M0083). These grain-size data were used to build a facies sequence that is applied to identify and interpret event-bed deposition in a hadal trench environment. The sediment cores were collected using a giant piston corer (up to 40 m core length) and a trigger corer onboard R/V Kaimei during International Ocean Discovery Program (IODP) Expedition 386 "Japan Trench Paleoseismology" between 13 April and 1 June 2021. Grain-size data were generated using two complementary methods: laser diffraction with a Malvern Mastersizer 3000 at the Department of Geology (UIBK) and dynamic image analysis with a Camsizer X2 at the Disaster Prevention Research Institute (Kyoto University). Sampling followed two strategies: (i) systematic sampling at 1–2 cm intervals and (ii) site-specific sampling of selected coarse- and fine-grained facies of event beds and hemipelagic sediments. For the systematic dataset, Event Bed 2 was analyzed in one core (M0083D), and Event Bed 3 in six cores (M0091B, M0091D, M0090B, M0090D, M0083B, and M0083D). For the site-specific dataset, the four event beds were sampled in eleven cores (M0083B, M0083D, M0083F, M0089A, M0089B, M0089D, M0090A, M0090B, M0090D, M0091B, and M0091D). This compilation provides a reference dataset for refining facies models that advances event stratigraphy and improves global understanding of deep-marine sedimentary dynamics.