The Cenozoic marginal basins of the Northwest Pacific (Okhotsk, Japan, South China, Sulu, and Celebes seas) share a first-order tectono-stratigraphic succession — Palaeocene–Eocene rifting, Oligocene–Middle Miocene drifting and back-arc spreading, and late Middle Miocene–present subsidence and convergence — yet they express this pattern differently: the South China Sea records a separated rift-then-drift sequence, while the Japan and Okhotsk seas show rifting and drifting synchronous in the Oligocene–Middle Miocene with no preserved early rift stage. Xu et al. (2016), who established this comparative framework, flagged the divergent rifting histories as difficult to explain at present and the mechanisms linking regional plate motions to basin-specific sequence styles as unresolved. Recent work shows genuine but partial progress — Kuril Basin opening now constrained to about 25–26 Ma by radiometric dating, a detailed published model of Sulu arc–basin evolution, two-stage rifting documented on the South China Sea margin, and rival slab-pull, extrusion, and hybrid models for South China Sea opening — but no published mechanism resolves the inter-basin contrast or the general plate-motion-to-sequence-style link. The problem remains open.

Background

Marginal (back-arc) basins are small oceanic or strongly thinned continental basins trapped between a continent and an island arc, generally formed by extension above an active subduction zone; the Northwest Pacific margin carries a chain of them, including the Okhotsk, Japan, South China, Sulu, and Celebes seas. Their Cenozoic fill is read through sequence stratigraphy — the ordering of genetically related sedimentary packages ("sequences") bounded by unconformities, which records the interplay of tectonic subsidence, global sea-level change, and sediment supply; a basin's "sequence pattern" is its first-order tectono-stratigraphic succession. Xu et al. (2016) compared the sequence patterns of these five basins and found a shared first-order, three-stage Cenozoic succession: (1) Palaeocene–Eocene rifting, i.e. continental extension expressed in fault-bounded half-grabens filled with terrestrial to lacustrine deposits; (2) Oligocene–Middle Miocene drifting, i.e. seafloor (back-arc) spreading that in several basins produced oceanic crust and marine deposition; and (3) late Middle Miocene–present regional subsidence and convergence, with thermal sag and partial inversion of the earlier extensional structures. The basins differ, however, in how these stages are expressed. The South China Sea (SCS) — the largest western Pacific marginal sea — shows a separated, sequential rift-then-drift pattern: an early rift stage is preserved on its northern margin (independently corroborated by documented Paleocene rapid exhumation of Hong Kong; Zhang et al., 2023), and two-stage Paleogene rifting (oblique extension at roughly 44–42 Ma, then transtension to about 21 Ma) is documented in its rift basins (Wang et al., 2021), followed by Oligocene–Middle Miocene spreading. The Japan and Okhotsk seas, in contrast, lack a preserved Palaeocene–Eocene rift stage: there, rifting and drifting appear synchronous within the Oligocene–Middle Miocene. What drives the opening of such basins is itself contested: candidate mechanisms include extrusion (tectonic escape of continental blocks driven by the India–Eurasia collision), slab pull from retreating or detaching subducted slabs beneath the Pacific margin, and hybrids of both — a debate kept live by rival models of SCS opening (Larvet et al., 2023; Wang et al., 2025; Liu et al., 2023). Xu et al. (2016) also flagged observational gaps that any mechanism must eventually answer: the origin and full sequential stratigraphy of the Sulu Sea Basin are still not well understood, the Celebes Sea Basin sequence pattern is not clearly established, and the timing and detailed development of the rifting stage remain uncertain in basins lacking deep drilling, notably the Kuril Basin of the Okhotsk Sea.

Problem Statement

Identify the tectonic mechanisms by which the shared regional plate-motion history of the Northwest Pacific produced the observed basin-specific Cenozoic sequence styles — in particular, explain why the South China Sea followed a separated Palaeocene–Eocene rifting stage and subsequent Oligocene–Middle Miocene drifting, whereas the Japan and Okhotsk seas record rifting and drifting synchronous in the Oligocene–Middle Miocene with no preserved early rift stage. The mechanism must explain the South China Sea versus Japan/Okhotsk contrast and must not contradict the documented per-basin records. The unresolved gaps flagged by the source synthesis — the origin and full sequential stratigraphy of the Sulu Sea Basin, the sequence pattern of the Celebes Sea Basin, and the timing and detailed development of the rifting stage in basins lacking deep drilling, such as the Kuril Basin — bear on any proposed mechanism as consistency constraints: it must not contradict what is documented about them.

References

  1. Xu, Shumei; Ye, Qing; Li, Sanzhong; Somerville, Ian; Feng, Huaiwei; Tang, Ziwen; Shu, Dongge; Bi, Haiming (2016). Sequential patterns in Cenozoic marginal basins of the Northwest Pacific. Geological Journal 51(S1):387–415. DOI 10.1002/gj.2819. https://doi.org/10.1002/gj.2819
  2. Wang, Pengcheng; Li, Sanzhong; Suo, Yanhui; Guo, Lingli; Santosh, M.; Li, Xiyao; Wang, Guangzeng; Jiang, Zhaoxia; Liu, Bo; Zhou, Jie; Jiang, Suhua; Cao, Xianzhi; Liu, Ze (2021). Structural and kinematic analysis of Cenozoic rift basins in South China Sea: A synthesis. Earth-Science Reviews 216:103522. DOI 10.1016/j.earscirev.2021.103522. https://doi.org/10.1016/j.earscirev.2021.103522
  3. Larvet, Tiphaine; Le Pourhiet, Laetitia; Pubellier, Manuel; Gyomlai, Thomas (2023). Slab Pull Driven South China Sea Opening Implies a Mesozoic Proto South China Sea. Geophysical Research Letters 50(22):e2023GL105292. DOI 10.1029/2023gl105292. https://doi.org/10.1029/2023gl105292
  4. Wang, Zheng; Ren, Jianye; Hu, Chen; Xu, Yancheng (2025). Differential Extrusion of Indochina–South China Block and Its Interplay With Slab-Pull Tectonics: Evidence for End-Oligocene Basin Inversion in the Beibuwan Basin. Tectonics 44(1):e2024TC008326. DOI 10.1029/2024tc008326. https://doi.org/10.1029/2024tc008326
  5. Liu, Jinping; Li, Sanzhong; Cao, Xianzhi; Dong, Hao; Suo, Yanhui; Jiang, Zhaoxia; Zhou, Jie; Li, Xiyao; Zhang, Ruixin; Liu, Lijun; Foulger, Gillian Rose (2023). Back-Arc Tectonics and Plate Reconstruction of the Philippine Sea–South China Sea Region Since the Eocene. Geophysical Research Letters 50(5):e2022GL102154. DOI 10.1029/2022gl102154. https://doi.org/10.1029/2022gl102154
  6. Zhang, Yulian; Zheng, Dewen; Li, Pengfei; Yu, Jingxing; Li, Chaopeng; Zhang, Wanfeng; Wang, Junjie (2023). Paleocene rapid exhumation of Hong Kong: Implications for the Cenozoic rifting along the northern margin of the South China Sea. Tectonophysics 868:230082. DOI 10.1016/j.tecto.2023.230082. https://doi.org/10.1016/j.tecto.2023.230082
  7. Werner, Reinhard; Baranov, Boris; Hoernle, Kaj; Bogaard, Paul van den; Hauff, Folkmar; Tararin, Igor (2020). Discovery of Ancient Volcanoes in the Okhotsk Sea (Russia): New Constraints on the Opening History of the Kurile Back Arc Basin. Geosciences 10(11):442. DOI 10.3390/geosciences10110442. https://doi.org/10.3390/geosciences10110442
  8. Lai, Chun-Kit; Xia, Xiao-Ping; Hall, Robert; Meffre, Sebastien; Tsikouras, Basilios; Rosana Balangue-Tarriela, Maria Ines; Idrus, Arifudin; Ifandi, Elena; Norazme, Nur 'aqidah (2021). Cenozoic Evolution of the Sulu Sea Arc-Basin System: An Overview. Tectonics 40(2):e2020TC006630. DOI 10.1029/2020tc006630. https://doi.org/10.1029/2020tc006630
  9. Cadenas, Patricia; Ranero, César R. (2024). Structure and Tectonic Evolution of the NW Sulu Sea Basin (SE Asia). Journal of Geophysical Research: Solid Earth 129(3):e2022JB026180. DOI 10.1029/2022jb026180. https://doi.org/10.1029/2022jb026180
  10. Wang, Shuai; Zhang, Guoliang (2022). Geochemical constraints on source nature and recycled oceanic crust in the mantle of the Celebes Sea. Lithos 418–419:106685. DOI 10.1016/j.lithos.2022.106685. https://doi.org/10.1016/j.lithos.2022.106685
  11. Emelyanova, T. A.; Petrishchevsky, A. M.; Izosov, L. A.; Lee, N. S.; Pugachev, A. A. (2020). Late Mesozoic–Cenozoic Stages of Volcanism and Geodynamics of the Sea of Japan and Sea of Okhotsk. Petrology 28(5):418–430. DOI 10.1134/s0869591120050021. https://doi.org/10.1134/s0869591120050021