Transition from buckling to subduction on strike-slip continental margins: Evidence from the East Sea (Japan Sea)

Abstract

Initiation of subduction is rarely encountered in modern tectonic environments due to its ephemeral and destructive nature. We report the geological and geophysical evidence indicating a transitional phase from buckling to embryonic subduction along the eastern Korean margin. The transition appears to be caused by compressional reactivation of the strike-slip boundary between the continental (Korean Peninsula) and oceanic (Ulleung Basin) crusts since the Early Pliocene. Evidence for compressional reactivation includes (1) a west-dipping major thrust and coincident crustal buckling of the Ulleung Basin; (2) an east-west structural asymmetry inferred from the gravity anomaly and P-wave tomography; and (3) ongoing crustal uplift and high-angle faults along the eastern Korean margin. The juxtaposition of underthrusting and buckling of the crust in the Ulleung Basin, and its associated ubiquitous reverse faulting on the eastern Korean margin, imply the potential development of a new subduction system along the western margin of the East Sea (Japan Sea). We propose that the East Sea comprises two incipient subduction margins (i.e., the Korean and Japanese sides), which are now competing to reach a self-sustaining subduction stage.

Tectonic Inversion and Geomorphic Evolution of the Algerian Margin Since Messinian Times: Insights From New Onshore/Offshore Analog Modeling Experiments

“…Most of the time, these objects are represented by advanced stages of inversion nowadays incorporated in the heart of mountain ranges (e.g., Beltrando et al., 2014; Carmignani et al., 2004; Shail & Leveridge, 2009; Vanbrabant et al., 2002). If several field examples are documenting early stages of fossil margin inversion, the ongoing inversion of passive margins witnessing a process of subduction initiation is seldom found because it represents a short, transient phase before the onset of stable subduction (Kim et al., 2018; Stern & Gerya, 2018). The central Algerian margin (Western Mediterranean Sea, Figure 1) represents, then, one of the rare and best examples of present‐day inversion of a passive margin in the early stages.…”

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

“…The volcanic structures were formed at the late Early Miocene, while large‐scale volcanic extrusions occurred in the central and northwestern regions during the post‐rift phase of the Ulleung Basin (Kim et al., 2020). The elongated thrust faults located in the basin centre have been forming by underthrusting beneath the eastern Korean Peninsula since the Early Pliocene (Kim, Yoon, Kim, & So, 2018). Thus, these topographic highs appear to have had no direct effect on the transport flows and sedimentation patterns of the DLCs.…”

“…Bathymetry in meters (Lee & Kim, 2002). The interpretation of major thrust is from Kim et al (2018). For locations, see Figure 2.…”

Ongoing Inversion of a Passive Margin: Spatial Variability of Strain Markers Along the Algerian Margin and Basin (Mediterranean Sea) and Seismotectonic Implications

“…Buckling (or folding) of the oceanic lithosphere is another expected effect of compressional reactivation that is indeed observed coincidently with underthrusting, faulting and prior to subduction initiation (e.g., Stein et al, 1989;Kim et al, 2018). Buckling may occur at crustal or lithospheric levels, depending on the coupling between the upper crust and the lithospheric mantle (Cloetingh et al, 1999;Burov, 2011).…”

“…Whether a passive margin is prone to focus strain and how the stressed oceanic lithosphere behaves depend on various parameters such as the geometry of the margin, the structure and nature of the continent-ocean transition and the mechanical and thermal properties of the lithosphere (e.g., Nikolaeva et al, 2010;Kim et al, 2018). It appears therefore essential to constrain these parameters in order to try to understand the mechanics of subduction initiation.…”