Mechanism of long-standing Cenozoic basin formation in central Hokkaido: an integrated basin study on an oblique convergent margin

Abstract

The basin-forming process along a convergent margin off the eastern coast of Eurasia was pursued on the basis of geological, geochemical, and geophysical approaches. Central Hokkaido has been a site of vigorous tectonic events throughout the Cenozoic reflecting the long-standing subduction of oceanic plates in the region. Geochemical modeling provided an estimate of the eroded Paleogene unit in the study area. Data on the considerable thickness of the missing unit implied continued subsidence of the forearc region and its subsequent exhumation under the emergence of a compressive regime synchronous with the back-arc opening stage. Spatially large facies variety in the Paleogene system suggests that basin compartmentalization occurred as a result of the trench-parallel component of the plate convergence. Right-lateral motion seems to have been the dominant type in Hokkaido and the forearc of northeast Japan since the Late Cretaceous, except for a left-lateral episode during rapid subsidence of the Izanagi Plate around 110 Ma. Numerical modeling demonstrated that dextral slip on a bunch of longitudinal strike-slip faults restored the Neogenedepocenters in central Hokkaido, together with an east-west compressive regime related to an arc-arc collision.

Evolutionary process of Beppu Bay in central Kyushu, Japan: a quantitative study of the basin-forming process controlled by plate convergence modes

“…A recent synthesis of the basin architecture of active plate margins (Itoh 2013) revealed that the modes of plate convergence (subduction rate, obliquity, slab steepness, etc.) play a crucial role in determining basin evolution patterns (e.g., Itoh et al 2014;Takano et al 2013). In other words, spatial/temporal variations in sedimentary basin morphology on an active margin give clues to changes in the convergence modes of oceanic plates and to regional tectonic history.…”

Fluvial to bay sequence stratigraphy and seismic facies of the Cretaceous to Paleogene successions in the MITI Sanriku‐oki well and the vicinities, the Sanriku‐oki forearc basin, northeast Japan

“…This ridged forearc basin setting is considered to have lasted until the Oligocene unconformity (Ounc) event, according to the previous regional tectonics studies (Itoh, Takano, Kusumoto, & Tamaki, ; Takano et al, ). Since then, the Sanriku‐oki forearc basin has exhibited a subsiding, extensional, nonaccretionary forearc setting without any trench slope break uplift (Noda, ; Takano et al, ).…”

Tectonic Synthesis: A Plate Reconstruction Model of the NW Pacific Region Since 100 Ma

“…The strong sinistral phase was replaced by a dextral phase in the Late Cretaceous. Based on the counterclockwise and then clockwise rotational sequence of a large pluton in northeast Japan revealed by paleomagnetic methods, Itoh et al [16] argued that switching from left-to right-lateral slips on arc-parallel faults resulted in a ball-bearing clockwise motion of crustal blocks. Such a deformation mode spread over the forearc basin of northeast Japan [17] and Hokkaido and lingered through the Paleogene.…”