Oil & Gas Geology ›› 2023, Vol. 44 ›› Issue (3): 735-752.doi: 10.11743/ogg20230316

• Petroleum Geology • Previous Articles     Next Articles

Source-to-sink coupling and temporal-spatial evolution in the Lishui Sag of East China Sea Shelf Basin during the Paleocene

Zhenjun ZHU1(), Qi LI1,2, Hehe CHEN1,2, Jian LI3, Weiping ZHANG4, Fengfan YANG5, Yingzhao ZHANG6, Jun QIN6, Fengxun LI7, Shuaiqiang SHAN7   

  1. 1.School of Ocean Sciences,China University of Geosciences (Beijing),100083,China
    2.Marine and Polar Research Center,China University of Geosciences,Beijing 100083,China
    3.Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China
    4.Xinjiang Xinchun Petroleum Development Company,SINOPEC,Dongying,Shandong 257026,China
    5.Yunnan Natural Gas Co. ,Ltd. Kunming,Yunnan 650200,China
    6.Shanghai Branch,CNOOC,Shanghai 200335,China
    7.Wuxi Branch of Petroleum Exploration and Production Research Institute,SINOPEC,Wuxi,Jiangsu 214126,China
  • Received:2022-12-05 Revised:2023-02-23 Online:2023-06-01 Published:2023-06-05

Abstract:

The source-to-sink systems in rifted basins are generally complex as a result of multi-stage tectonic activities and multiple provenances and drainage systems both within and outside the basins. The coupling relationship and spatial-temporal evolution of these systems in different tectonic stages are in need of in-depth study. Based on analyses of 3-D seismic data, well logging, cores, thin sections and heavy minerals of the Paleocene Lishui Sag in the East China Sea Shelf Basin, this study attempted to reconstructed the source-to-sink system for the Sag through sediment provenances analyses, transport channels identification and (quantitative) tracing, depositional system mapping and (half-quantitative) characterization. The results show that the early syn-rift stage was characterized by isolated sinks, small depositional centers, low tectonic activity rate, and inadequate sediment supply, with small and numerous fan deltas well-developed in gentle slope zones and small braided river deltas developed in steep slope zones. The main syn-rift stage witnessed sufficient sediment supply, larger but fewer fans developed in steep slopes and the braided river delta enlarged and combined into larger ones in gentle slopes, due to intensive faulting activities. The late syn-rift stage experienced the gradual disappearance of fault-related source-to-sink systems and the development of large floor fans at the slope break zones due to the ever-incrementing river incision as the gentle slope zones were under the influence of rapidly dropping sea level. Under the joint control of tectono-sedimentary pattern, parent rock types and boundary conditions, five source-to-sink systems were developed during different tectonic stages: ① metamorphic rock-dominated parent rocks—SE-trending U-shaped paleo-valley—braided river delta in the northern gentle slope zone, ② volcanic rock-dominated parent rocks—NE-trending faulted-trough /SE-trending V/U-shaped paleo-valley—braided river delta/basin floor fan in the southern gentle slope zone, ③ intrusive rock-dominated parent rocks—SW-trending paleo-valley—fan delta in the northern part of the Lingfeng Uplift, ④ volcanic rock (in early stage)/metamorphic rock (in late stage)—SW-trending paleo-valley/NE-trending faulted-trough—proximal fan delta system in the southern section of Lingfeng Uplift, and ⑤ intrusive and metamorphic rocks—SW/S-trending paleo-valley—fan delta/braided river delta in the Yandang Uplift. Quantitative statistical results of sediment routing systems show that the paleo-valleys and faulted trough in gentle slope zones are wide and shallow, whereas those in the steep slope zones are narrow and deep. The cross-sectional areas of the sediment routings in the early and late syn-rift stages display a positive correlation with the areas of corresponding fan/delta complexes in the Sag.

Key words: rifted basin, source-to-sink system, tectonism-sedimentation, Paleocene, Lishui Sag, East China Sea Shelf Basin

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