Journal of Marine Sciences ›› 2020, Vol. 38 ›› Issue (4): 1-15.DOI: 10.3969/j.issn.1001-909X.2020.04.001

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The internal structure and evolution of the middle Diaoyudao Uplift in the East China Sea

LI Kedi, LI Chunfeng*, YAO Zewei, TAO Tiansheng   

  1. Ocean Collage, Zhejiang University, Zhoushan 316021, China
  • Received:2020-10-30 Online:2020-12-15 Published:2020-12-15

Abstract: Due to the lack of geological and geophysical data of the Diaoyudao Uplift, the previous studies on this area are unsystematic, so there are many controversies about its tectonic evolution. Based on gravity, magnetic, and multichannel seismic data, the tectonic and sedimentary characteristics of the middle Diaoyudao Uplift were analyzed, which located to the east of the Xihu Depression, East China Sea Basin. The evolution model of the middle Diaoyudao Uplift was further refined. More residual sags are found in the north than in the south of the middle Diaoyudao Uplift. Accordingly, the middle Diaoyudao Uplift can be divided into the north and south segments. The boundary of the two segments is on the extended trace of the Zhoushan-Guotou Fault. In addition, magmatic intrusions are confined below the T20 unconformity in the west, whereas a basement pinnacle caused by magmatic activity exists in the east. It is found that the gradient zone of gravity anomaly corresponds exactly to the western edge of the basement pinnacle. Taking the west edge of the basement pinnacle as the boundary, the middle Diaoyudao Uplift can be divided into two parts from west to east. And the western zone can be further divided into two subzones, including part Ⅰ with magnetic rocks and part Ⅱ with residual sags. The western part of the middle Diaoyudao Uplift is from the strong tectonic and magmatic deformation of the eastern Xihu Depression, whereas the east part retained the original Diaoyudao Uplift. The comprehensive analysis of above features showed that the present-day middle Diaoyudao Uplift was formed by many episodes of tectonic events and magmatic activities around an ancient uplift.

Key words: the middle Diaoyudao Uplift, magmatism, inner divisions, tectonic evolution

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