Delta development and channel incision during marine isotope stages 3 and 2 in the western South Yellow Sea Jian Liu a,b, ⁎, Yoshiki Saito c , Xianghuai Kong b , Hong Wang b , Chun Wen d , Zigeng Yang b , Rei Nakashima c a Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources, Qingdao, 266071, PR China b Qingdao Institute of Marine Geology, Qingdao, 266071, PR China c Geological Survey of Japan, AIST, Central 7, Higashi 1-1-1, Tsukuba, Ibaraki 305-8567, Japan d Ocean University of China, Qingdao, 266003, PR China abstract article info Article history: Received 23 March 2010 Received in revised form 15 August 2010 Accepted 4 September 2010 Available online 16 September 2010 Communicated by J.T. Wells Keywords: South Yellow Sea paleo-channels paleo-delta Late Pleistocene sea-level changes Approximately 4100 km of high-resolution seismic profiles recently obtained from the western South Yellow Sea were subdivided into seven seismic units by six major seismic surfaces. Three sediment cores between 60 and 71 m in length, obtained from localities on the seismic profile lines, were analyzed for sedimentary characteristics, clay mineral components, and benthic foraminiferal and ostracod assemblages and were also dated by AMS 14 C and optically stimulated luminescence to document the environmental history of the region. Stratigraphic units in the cores were confidently correlated with seismic units in the profiles. Stratigraphic correlation among these three cores and the previous well-studied core QC 2 was facilitated by the cold-water deposits in marine isotope stage (MIS) 5. The three cores document the sedimentary sequence during the period from MIS 6 up to MIS 1. Strata formation and sedimentary environment changes since MIS 5 are strongly controlled by sea-level fluctuations. Most of the successions were formed in MIS 5, MIS 3, and MIS 1 with major erosions in MIS 4 and MIS 2. Particularly our data revealed the presence of a large delta active during MIS 3 (likely from the early stage of MIS 3 to about 40 cal kyr BP) that was subsequently affected by channel incision. The delta succession and incised-channel fills have a high concentration of smectite in their clay mineral components, suggesting that the paleo-Yellow River was the main contributor to the delta development and channel incision. The delta sequence has a coarsening-upward trend and consists of two seismic facies. The upper facies shows lateral alternations of chaotic and oblique or very low-angle reflectors, which correspond to sandy (proximal) delta-front and delta-plain facies, and the lower facies is characterized by seaward-dipping clinoforms, which correspond to muddy (distal) delta-front and prodelta facies. The top surface of the delta inclines very gently seaward, consistent with a deltaic development associated with the sea-level fall in MIS 3. The incised-channel system consists of two main channels with multiple tributaries in a dendritic pattern. The incised-channel fills begin with fluvial and then estuarine sediments, which are truncated by a transgressive ravinement surface and capped by transgressive deposits. The main incision channels have a terraced cross-sectional morphology, which is interpreted to reflect multiple episodes of sea- level fall during incision, presumably from the late MIS 3 to the Last Glacial Maximum. © 2010 Elsevier B.V. All rights reserved. 1. Introduction In response to multiple cycles of relative sea-level change and associated subaerial exposure, many continental shelves contain stacked delta and coastal-plain sequences with buried fluvially incised surfaces and incised-channel fills; examples include the New Jersey shelf (Steckler et al., 1999) and Gulf of Mexico shelf (Morton and Suter, 1996) in North America and the East China Sea shelf (Wellner and Bartek, 2003) in Asia. Late Pleistocene channel incisions, in particular, are documented on continental shelves worldwide (e.g., Foyle and Oertel, 1997; Nordfjord et al., 2005; Simms et al., 2007; Green, 2009) by high-resolution seismic profiling and coring. Many shelves were subaerially exposed when sea level fell by 120 m during the Last Glacial Maximum (LGM), and as a result, fluvial channels extended to the shelves and cut through the underlying strata in response to drops in base level (Talling, 1998), as sequence stratigraphic models predict (Van Wagoner et al., 1988; Posamentier et al., 1992). Great attention has been paid to the forcing mechanisms, geomorphology, and ages of these successions of fluvial incisions and fills (e.g., Blum and Törnqvist, 2000; Nordfjord et al., 2005, 2009), providing insight into the development and sedimentary processes of shelves. The South Yellow Sea (SYS) is a shallow, semi-closed, epiconti- nental sea between the Korean peninsula and China (Fig. 1), with Marine Geology 278 (2010) 54–76 ⁎ Corresponding author. Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources, Qingdao, 266071, PR China. E-mail address: liujian0550@vip.sina.com (J. Liu). 0025-3227/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.margeo.2010.09.003 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margeo