Paleoenvironmental changes associated with the Holocene marine transgression, Yellow Sea (Hwanghae)

Benthic foraminiferal and stable isotopic data from two radiocarbon dated cores from the Yellow Sea record paleoenvironmental changes largely associated with the Holocene marine transgression The Holocene marine transgression began significantly earlier (12.9 ka) in the central part of the Yellow Sea (as recorded in 278 cm long core CC-02; water depth, 77.5 m) compared with 7.9 ka in a tidal hat on west coast of Korea (as recorded in 350 cm long vibra-core DH4-1; water depth 1.8 m). The benthic foraminiferal assemblages in the lower part of CC-02 and the entire marine sequence of DH4-1 are dominated by assemblages characteristic of shallow (<20 m water depth), low salinity water species [Ammonia beccarii (Linne), Elphidium advenum (Cushman) and Cribrononion subincertum (Asano)]. delta(18)O and delta(13)C values of A. beccarii in this interval are very low (-4.1 to 0.2% and -3.7 to -0.7%, respectively) reflecting the influences of fresh waters and associated input of terrestrial organic carbon in shallow, coastal environments (12.9 to 7.9 ka in CC-02; 7.6 ka to Recent in DH4-1). After similar to 7.5 ka benthic foraminiferal assemblages in the central Yellow Sea (CC-02) were replaced by species characteristic of less brackish, deeper (>50 m) waters [Ammonia ketienziensis (Ishizaki), Astrononion italicum Cushman and Edwards and Hanzawaia nipponica (Asano)]. After similar to 7.5 ka in the central Yellow Sea, much higher delta(18)O (1.6 to 1.8%) and delta(13)C (-0,1 to -0.7%) values of A. ketienziensis reflect a change to more open-ocean, higher salinity environments, with deeper waters dominated by the Hwanghae Cold Water as in the present day. (C) 1998 Elsevier Science B.V. All rights reserved.