Evidence for a second deflected prodelta of the Yellow River: Insights into a complex pattern of delta asymmetry

Pollen and spore records constrained by millennial prodelta evolution: a case study of the Huanghe (Yellow River) delta

“…In Panel (A), historical shorelines (grey, black, and orange dashed lines with age labels) and the winter coastal current system (representative of long-term transport patterns) are superimposed (after Xue et al, 2018). Panel (B) illustrates subaqueous mud (blue fill) formed since the mid-Holocene highstand period, also known as the subaqueous highstand systems tract (HST), primarily composed of prodeltaic sediments (Liu et al, 2022). Isopachs of HST in the western and northwestern Bohai Sea, along with the positions of seismic profiles (bold black lines) and sediment cores from this study (yellow circles) and previously published data (blue circles) detailing in Figures 2-4 2022), outlining boundaries of the Luanhe River prodelta, erosiondominated area, and Huanghe-dominated prodelta with dashed orange lines.…”

“…The subaqueous delta clinoform of the Huanghe, as the subaqueous extension of the Huanghe delta plain, is situated predominantly in the western Bohai Sea with a thickness of up to 20 m (Figure 1B) (Liu et al, 2019). Dominated by eastward/ southeastward and northeastward coastal currents, the Huanghe prodelta experiences deflection along these two directions, resulting in the formation of a unique dual-mud belt system (Figure 1B) (Liu et al, 2022). The eastward/southeastward deflected prodelta (mud belt) eventually reaches east of the Bohai Strait, entering the Yellow Sea and forming a mud wedge (up to ~40 m thick) offshore of the Shandong Peninsula (Yang and Liu, 2007).…”

“…The northeastward deflected prodelta extends to the offshore regions of the Luanhe delta and even farther northeast, forming a depocenter (~10 m thick) near the furthest end of this mud belt (Figure 2C). This mud belt is separated from the adjacent Luanhe River prodelta (attached to the Luanhe River delta plain) by a shore-parallel erosiondominated sandy region, which is ~10-20 km in width (Figure 1B) (Liu et al, 2022).…”

“…Due to energetic longshore transport regimes, transgressive sand sheets have transformed into a series of alongshore-arranged erosional ridges, a phenomenon particularly pronounced in the erosion-dominated region (Figures 2C, D). Consequently, HST sediments have been partitioned by this erosional region along the shore-normal direction, with (1) a wedge attached to the Luanhe River delta plain corresponding to the Luanhe River-dominated prodelta, (2) isolated mud patches filling the troughs among the ridges in the erosion-dominated area, and (3) the Huanghe-dominated prodelta, extending from coast to offshore (Figures 2C, D) (Liu et al, 2022).…”

“…To address this issue, we focus on the Huanghe delta, particularly its prodelta in the western and northwestern Bohai Sea, in this study, which, renowned as one of the largest deltas on Earth, has been extensively studied for its sedimentary and stratigraphic evolution in recent years (He et al, 2019;Liu et al, 2019Liu et al, , 2020Liu et al, , 2022. Building on the well-established seismic stratigraphy (Liu et al, 2019;2022), we utilized nine borehole cores and one gravity core (five newly acquired, five referenced from literature) (Table 1; Figure 1B) to establish seismic-to-core correlation and further examine the relationship between pollen and spore records and evolution of the prodelta stratigraphy.…”