Stratigraphic framework and evolution of the mid–late Quaternary (since marine isotope stage 8) deposits on the outer shelf of the East China Sea

Authigenic Iron Sulfides Indicate Sea‐Level Change on the Continental Shelf: An Illustration From the East China Sea

“…The AMS 14 C ages of the upper 44-m section are relatively young (∼3 kyr) with obvious stratigraphic reversals ( Figure 2a and Table 1), just as reported for core DG11 (Figure 1), which indicates that these tidal sand ridges probably formed around 2-3 kyr BP, or they are still in equilibrium with the modern hydrodynamic regime after their initial formation during the last deglacial transgression (Berné et al, 2002;Xu et al, 2020). The BF of the 21−32-m and 44−48-m sections are dominated by relict crusts (Figure 2d), but sedimentary features of the lower section are more consistent with a fluvial setting ( Figure S1).…”

“…It is also rich in cold‐water species of BF (Figure 6f), mainly Protelphidium tuberculatum and Buccella frigida (Table S1). These results indicate that DU 2 was deposited in a prodelta setting and was affected by cold coastal currents (Xu et al., 2020). DU 3 (∼44–48 m, corresponding to Unit 4), as above‐mentioned, was deposited in a terrestrial setting, as indicated by both the sedimentary features (Figure S1) and the extremely low abundance of BF that are dominated by relict crust (Figures 2c–2d).…”

“…(2002), and Xu et al. (2020), respectively. The abbreviations of oceanic circulations in (a) denote the Kuroshio Current, KC; Taiwan Warm Current, TWC; Yellow Sea Warm Current, YSWC; Yellow Sea Coastal Current, YSCC; Zhejing‐Fujian Coastal Current, ZFCC; and Changjiang Diluted Water, CDW.…”

“…The ECS has a total area of 773,000 km 2 , and ∼2/3 of this area is occupied by the continental shelf, which is one of the broadest shelves in the world and is usually divided geomorphologically into the inner and outer shelf by the 50–60 m isobath (Liu et al., 2000). Because of its large width (around 400–500 km), low gradient (<0.02° on average), and relatively shallow water depths (generally < 130 m), the shelf is highly sensitive to sea‐level change (Xu et al., 2020). It has received a large quantity of terrigenous matter in response to the high level of sediment discharge from the Yangtze River and sufficient accommodation space due to the high subsidence rates of ∼300 m/Myr during the Quaternary (Berné et al., 2002).…”

“…It was recovered using the rotary drilling method in September 2015, with a total drilling length of 101.6 m and an average recovery rate of 81.56%. According to core descriptions and grain-size analysis, using the same methods as Xu et al (2020) employed on core DH02 (Figure 1), fine sand dominates the upper ∼48-m section of the core, while clayey silt, sandy silt or fine sand alternately dominates the lower ∼53-m section (Figure 2a). The chronology of core DH03 was established by integrating accelerator mass spectrometer (AMS) 14 C ages of epibenthic foraminiferal tests measured by Beta Analytic Inc. (Table 1; see Liu et al, 2010 for the details of calibration), microfossil analysis (see Xu et al, 2020 for the methods followed), sedimentary features, and the chronostratigraphy of cores DZQ4 (Liu et al, 2000) and DH02 (Xu et al, 2020) (Figure 1), as outlined below.…”