Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (4): 792-803.doi: 10.11743/ogg20220405

• Petroleum Geology • Previous Articles     Next Articles

Sequence stratigraphic framework and model of mixed siliciclastic-carbonate rocks in the Qingbaikouan System, Longshan area, North China

Qin Zhang1,2, Chen Zhou3, Hanyun Tian1, Xiaomin Zhu1,2, Xinsong Wu1,2, Zeping Song1, Kai Wang1   

  1. 1.College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China
    2.State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China
    3.Shengli Oil Production Plant,Shengli Oilfield Company,SINOPEC,Dongying,Shandong 257000,China
  • Received:2022-04-07 Revised:2022-05-01 Online:2022-07-14 Published:2022-07-14

Abstract:

The Neoproterozoic in the Longshan area, North China, is well exposed. With clastic rocks and carbonates developed successively from bottom to top, the strata serves as an ideal subject for the study of sequence stratigraphic framework and sedimentary facies evolution, which has been considered significant to the paleogeographic reconstruction of North China. Field and lab analyses of lithologic characteristics and sedimentary sequences of the strata are combined with the regional tectonic movement to establish the isochronous sequence stratigraphic framework, analyze the sedimentary facies evolution, and build up the sequence stratigraphic development model. The results show that according to the unconformities and lithologically abrupt interfaces, the Neoproterozoic Qingbaikouan System can be divided into three third-order sequences from bottom to top: the SQ1 (Xiamaling Formation), SQ2 (Changlongshan Formation) and SQ3 (Jingeryu Formation), each consisting of transgressive systems tract (TST) and highstand systems tract (HST). The SQ1 and SQ2 sequences are mainly composed of clastic rocks indicating sufficient input of terrigenous clastics. The SQ3 sequence is dominated by mixed siliciclastic-carbonate rocks against a relatively clear water depositional setting. The lithological characteristics, sedimentary structures and superposing styles, all point to shallow sea shelf facies for the SQ1-TST, and subtidal sand flat and intertidal mixed sand-mud flat for the SQ1-HST. The SQ2-TST mainly develops subtidal sand flats and tidal channels, while SQ2-HST mainly develops intertidal mixed sand-mud flats and supratidal mud flat. The SQ3-TST develops subtidal sandy shoal and argillaceous limestone flat, while SQ3-HST mainly develops intertidal dolomitic limestone flat and supratidal calcareous and argillaceous dolomite flat. Based on the understanding, a sequence stratigraphic development model of mixed siliciclastic-carbonate rocks dominated by tidal flat-shallow sea shelf facies is established, indicating the possibility of an open epicontinental sea with gentle slopes.

Key words: tidal flat facies, sequence stratigraphic framework, sequence stratigraphic development model, mixed siliciclastic-carbonate rock, Qingbaikouan System, Neoproterozoic, Longshan area, North China

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