Tectonic control on mass‐transport deposit and canyon‐fed fan system in the Ulleung Basin, East Sea (Sea of Japan)

Abstract

Abstract Extensive 2D multichannel seismic (~17340 km) and well data provide an opportunity to investigate the source to sink processes and triggering factors of the Late Miocene sedimentary record in the Ulleung Basin, East Sea (Sea of Japan). The sedimentary succession of the basin comprises two distinct deep‐water depositional systems, which are characterised by stacked mass‐transport deposits (MTDs) and subsequent submarine fan. Individual MTDs spread downslope over areas as large as ~9000 km 2 with NW–SE or N–S flow direction. The deep‐water fan consists of distributary channel‐lobe complexes (DLCs) that are 80 km wide and 140 km long. Two major tectonic periods driven by structural deformation characterised the Late Miocene deep‐water sedimentation growth. During early to middle Late Miocene (10.3–8.2 Ma), the MTDs were sourced from degraded fold triggered by slope oversteepening and seismicity on the southeastern basin margin, where the thrust‐and‐fold belt developed. In the middle to latest Late Miocene (8.2–6.3 Ma), the DLCs were fed by canyon‐channel systems on the southwestern basin margin, where the tectonic uplift of the anticline was active. Therefore, this study suggests that strike variation in shelf‐margin erosional and depositional processes were caused principally by the locations and timings of tectonic deformation.