Advances in Earth Science

   

Variability of the Shelf-edge Sequence Architecture and its controlling factors in the western part of the late Pleistocene Qiongdongnan Basin, South China Sea

GE Jiawang1, TANG Xiaolong1, ZHAO Xiaoming1, ZHU XiaoMin2, QI Kun1   

  1. (1. College of Geosciences and Technology, Southwest Petroleum University, Chengdu 610500, China; 2.College of Geosciences, China University of Petroleum, Beijing 102249, China)
  • About author:Ge Jiawang, Associated professor, rsearch areas include quantitative sequence stratigraphy, seismic sedimentology and petroleum development geology. E-mail: gjwddn@163.com
  • Supported by:
    Project supported by the Natural Science Foundation of Sichuan Province (Grant No.2023NSFSC0810); The National Natural Science Foundation of China (Grant No.42072183).

GE Jiawang, TANG Xiaolong, ZHAO Xiaoming, ZHU XiaoMin, QI Kun. Variability of the Shelf-edge Sequence Architecture and its controlling factors in the western part of the late Pleistocene Qiongdongnan Basin, South China Sea[J]. Advances in Earth Science, DOI: 10.11867/j.issn.1001-8166.2024.052..

Previous sequence stratigraphy research mainly focuses on the two-dimensional seismic interpretation in its dipping direction, while the variations of sequence architectures in vertical provenance direction is the focus and difficulty of current research. This study takes the Late Pleistocene (0.125 Ma to today) shelf margin stratigraphic successions of the Qiongdongdong Basin as an typical example. The internal structure and combination characteristics of the systems tract units are established and identified, according the methods of typical stratal terminations, stratal stacking patterns, and shelf-edge migration trajectory. The systems tract in the studied sequence are classified from bottom to top, including the lowstand systems tract (LST), the transgressive systems tract (TST), the highstand systems tract (HST), and the falling stage systems tract (FSST). Among them, the part of the interface within the falling stage systems tract (WSTS) divides the FSST into early and late phases. The WSTS interface is the transitional surface for the positive to negative angle of the migration trajectory of the shelf-edge and for the stratal stacking transition from progradation to degradation. The stabilized and collapsed types of shelf-edge sequence architectures have developed in the Upper Pleistocene of the western part of the eastern Qiongdongnan Basin. With the change of relative sea-level, the stabilized shelf-edge mainly develops multi-phase shelf margin deltaic and deep-water fan deposits, while the collapsed shelf-edge mainly develops large-scale canyons and mass transport deposits. In response to the a short sea-level rising but a prominent falling cycle, the late Pleistocene shelf-edge sequences are composed of thin or undeveloped LST and TST units, and a thick FSST unit, whereas the active faults in the outer shelf locations increase the proportion of the HST unit in sequences. The pre-existing slope break geomorphology, fault activities and asymmetric sea-level fluctuation coevally lead to a diverse of the sequence architectures in the study area. The quantitative exploration of highfrequency sequence stratigraphic driving mechanisms is the future development trend of the Pleistocene stratigraphy, and this study provides a potential reference significance for the standardization of 3D sequence stratigraphic investigations.
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