loading page

New magnetic data indicate successive ridge jumps and rotations of seafloor spreading in the South China Sea
  • +2
  • Jiabiao Li,
  • Qingsheng Guan,
  • Tao Zhang,
  • Brian Taylor,
  • Jinyao Gao
Jiabiao Li
Second Institute of Oceanography, State Oceanic Administration

Corresponding Author:[email protected]

Author Profile
Qingsheng Guan
Nanjing University
Author Profile
Tao Zhang
Second Institute of Oceanography, Ministry of Natural Resources, China
Author Profile
Brian Taylor
University of Hawaii at Manoa
Author Profile
Jinyao Gao
State Oceanic Administration
Author Profile


New shipborne surveys provide a closely spaced magnetic anomaly dataset covering the East Subbasin (ESB) of the South China Sea (SCS). Magnetic anomalies of seafloor spreading are identified using the dataset supplemented with previous data and age constraints from recent International Ocean Discovery Program Expeditions 349 and 367/368 holes. We present a high-resolution oceanic crustal age model and associated magnetic lineations of the ESB based on identified magnetic anomaly picks. Seafloor spreading in the ESB initiated at ~30 Ma (C11n) and terminated at ~16 Ma (C5Br). The spreading direction has experienced a gradual counterclockwise rotation between C6Cr and C5Er and a significant counterclockwise rotation at C5Dr. The spreading rotations reorganized the orientation and segmentation of the spreading ridge, resulting in the formation of a series of S-shaped fracture zones. The interpretation of the magnetic lineations reveals that three southward ridge jumps occurred at C9r, C8n, and C7n and a synchronous jump occurred at C5Dr. Three southward ridge jumps contributed to a total difference of ~184 km in the distance between the two flanks and left the paired magnetic lineations C10r–C7r on the present-day north flank. The synchronous jump caused the spreading ridge to rotate rapidly counterclockwise and obliquely intersect the existing seafloor. We postulate that these ridge jumps and rotations are common processes during seafloor spreading reorientation and are dynamic responses to the plate or microplate tectonics around the SCS.
Oct 2021Published in Terra Nova volume 33 issue 5 on pages 475-482. 10.1111/ter.12532