Discovery of contourite drifts on the outer rise along the Kuril Trench, Northwest Pacific
Journal
Marine Geology
Journal Volume
498
Start Page
107802
ISSN
0025-3227
Date Issued
2026-08
Author(s)
Ikeda, Hisashi
Nakanishi, Ryo
Kanamatsu, Toshiya
Fujiwara, Toshiya
Hsiung, Kan-Hsi
Kawamura, Kiichiro
Abstract
Contourite drifts are widely documented along passive margins, but their development on active-margin outer rises remains poorly understood. Here we document two large sedimentary bodies on the Kuril Trench outer rise, northwest Pacific, and evaluate whether they represent bottom-current-controlled contourite drifts on the incoming Pacific Plate. We integrate bathymetry, multichannel seismic profiles, sub-bottom profiler data, piston and pilot cores, X-ray computed tomography, physical-property records, and tephrochronology. The northeastern body forms an elongated tongue-shaped deposit adjacent to Ryofu–Daini Seamount and nearby knolls, whereas the southwestern body is a broad depositional body bordered by persistent flank depressions and mantled by a coherent sediment-wave field. Seismic profiles show a lower subparallel succession overlain by an organized upper succession with mounded to sheeted geometries, lateral asymmetry, flankward thinning, downlap, and local truncation. The upper succession is organized into three first-order architectural stages: localized relief-modulated deposition, main drift organization, and the youngest strongly asymmetric stage. Sub-bottom profiler data show shallow reflector continuity between flank-depression and drift-crest sites. Cores contain bioturbated diatomaceous mud from clay to sandy silt and lack repeated sharp-based event beds. Tephra correlation indicates event-free sedimentation rates of 4.3 cm ky r−1 at the flank-depression site and 12.4 cm ky r−1 at the drift crest. A first-order comparison with DSDP Site 436 suggests that drift development may have spanned the Late Miocene to the Quaternary. These results suggest that active-margin outer rises can host large, potentially long-lived contourite drifts where boundary-current flow, inherited relief, and fine-grained sediment supply coincide.
Subjects
Active margin
Contourite drift
Deep western boundary current
Kuril Trench
Lower circumpolar deep water
Northwest Pacific
Outer rise
Publisher
Elsevier BV
Type
journal article