Internal Facies Architecture and Evolution History of Changxing Mouth-Bar Complex in the Changjiang (Yangtze) Delta, China

• Published in: Journal of Ocean University of China Vol. 17; no. 6; pp. 1281 - 1289
• Main Authors: Su, Jianfeng, Fan, Daidu
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01-12-2018; Springer Nature B.V; School of Geoscience, Yangtze University, Wuhan 430100, China; State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China; State Key Laboratory of Estuarine and Coastal Research, Shanghai 200062, China%State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
• Subjects: Comparative analysis; Comparative studies; Deltas; Deposits; Earth and Environmental Science; Earth Sciences; Embankments; Evolution; Fluvial deposits; Meteorology; Oceanography; Progradation; Rivers; Sedimentary facies; Sedimentation; Sedimentation rates; Sequence stratigraphy; Sequencing; Strata; Stratigraphy; Tidal flats; Tides; Time lag; China, People's Republic, Changjiang River; delta evolution; Changxing Island; Changjiang Delta; tide dominated; river-mouth bar; facies architecture; sedimentary facies
• ISSN: 1672-5182; 1993-5021; 1672-5174
• DOI: 10.1007/s11802-018-3814-y

River-mouth bar is a fundamental element to constitute a delta system, and its internal facies architectures are vital to reconstruct delta evolution history and study high-resolution sequence stratigraphy. Changxing Island is a representative mouth-bar complex in the modern Changjiang Delta. Its vertical stacked strata produced by delta progradation were first studied by detailed facies analysis of core CX03, and then a general facies architecture and evolution history of mouth-bar complexes in the modern Changjiang Delta were discussed through a comparative study of 5 different cores and historical charts. A progradational deltaic sequence has generally a similar internal facies architecture, composed of massive muddy deposits of prodelta and delta-front slope facies at the bottom, sand-dominated deposits of delta-front platform, inter-bar channel and mouth-bar facies at the middle, and heterolithic deposits of tidal flat and saltmarsh facies at the top. There is a significant time lag for the initial formation of channel-mouth bar systems between Chongming and Jiuduansha Islands. Compared with subtidal flats, sedimentation rates on intertidal flats were highly accelerated, potentially resulting from weakening wave and tidal strength over extensive intertidal flats and increasing human embankment activities in the last few centuries. These findings provide some new clues to understand modern and ancient mouth-bar evolution and resultant sequence strata in tide-dominated deltas.