Late Quaternary environmental change in Oujiang delta along the northeastern Zhe-Min Uplift zone (Southeast China)

• Published in: Palaeogeography, palaeoclimatology, palaeoecology palaeoclimatology, palaeoecology, 2018-03, Vol.492, p.64-80
• Main Authors: Shang, Shuai, Fan, Daidu, Yin, Ping, Burr, George, Zhang, Mengying, Wang, Qiang
• Format: Article
• Language: English
• Subjects: East China Sea; Holocene; MIS 3; Paleosol; Sea-level change; Weak monsoon events
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2017.12.012

We present a history of late Quaternary coastal evolution based on the study of a 41.9-m-long sediment core from the Oujiang Delta. Multiple analytical methods are employed, including sedimentary facies analysis, radiocarbon dating, and the investigations of grain size, elemental, microfossil and pollen compositions. Two transgression-regression sequences, separated by a paleosol layer, are identified. Several lines of evidence indicate that the lower sequence was deposited during the mid-early MIS 3 stage, under a relatively warm and wet climate. An elevated MIS 3 highstand sea level (higher than −24m) is observed. The upper sequence was created after the paleosol was flooded during a marine transgression at ~9.5calkyr BP. Seven weak East Asian Summer Monsoon (EASM) events are identified with central years of ~8.4, 7.7, 6.3, 5.7, 4.7, 2.8 and 1.8calkyr BP. These coincide with those from the ECS sediment cores and the Dongge Cave δ18O record, indicating that EASM precipitation is a major controlling factor of sedimentation rates in the region. The Oujiang Delta is also subject to typhoon impacts and East Asian winter monsoon (EAWM)-induced coastal currents. Active typhoons and a relatively enhanced EAWM occurred during the weak EASM period between 4.9 and 6.4calkyr BP, producing high sedimentation rates in the middle Holocene. We emphasize the high sensitivity of small Asian river deltas as archives of the EASM, EAWM and typhoons. Such environments merit further as a means to understand past changes as well as future responses to projected climatic and sea-level change. •Late Quaternary coastal evolution in a small river delta is deliberately delineated.•Common presence of elevated MIS 3 highstand sea level (>−30m) is amply discussed.•Synchronous occurrence of weak East Asian summer monsoon events are recognized.•Small Asian river deltas are highlighted as archives of the EASM, EAWM and typhoons.