Tidal current-dominated depositional environments in the central-northern Yellow Sea as revealed by heavy-mineral and grain-size dispersals

This study confirms that the fine sand-sized detritus in the central-northern Yellow Sea is chiefly derived by the Yellow River and explains the Holocene Yellow River dispersal system and the preservation of transgressive deposits by heavy-mineral and grain-size analyses. Micas, which are sensitive to hydraulic sorting, offer an effective key for identifying the dispersal of Holocene Yellow River-derived fine-grained sediments. The heavy-mineral compositional changes are attributed to hydraulic sorting by different marine dynamics and various mixing with additional local transgressive deposits of miscellaneous provenance. The effects of hydraulic sorting are dominated by Holocene tidal currents and by foreshore waves during the rapid transgression, respectively. The former results in obvious enrichments of garnet and common stable species such as Ti oxides, tourmaline, and titanite, whereas the latter seems more remarkable for the compositional changes, with further depletion of epidote, actinolite/tremolite and zoisite/clinozoisite. The central Yellow Sea mud deposit and the alongshore muddy zone off the southern Liaodong Peninsula are opposite to each other as a pair of structurally symmetric coalesced terminal lobes far away from the high-energy strait between Cape Chengshan and Changsan-got. The Haiyang subaqueous clinoform as another terminal lobe is revealed by a heavy-mineral index, which represents an extremity of deposits accumulated by the modern Yellow River-derived sediments off the southwestern Shandong coast. A small mud patch is revealed, roughly corresponding to the central regime of the amphidromic system of principal M2 constituent. The tidal current-dominated depositional pattern proposed here emphasizes the importance of time-velocity asymmetry of tidal currents. Such a dynamic mechanism is primarily responsible for the dispersal of the modern Yellow River-derived sediments when they are entrained from the Bohai Sea to the South Yellow Sea through the Bohai Strait and the strait between Cape Chengshan and Changsan-got.