Assemblages of benthic foraminifera in a sediment core(C02)near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression.It appears that during the early Holocene(11.2 10.1 kyr BP),the faunal was dominated by low salinity and shallow water species Cribrononion subincertum,Buccella frigida and Ammonia beccarii,reflecting a near coast depositional environment.A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1 9.3 kyr BP indicates that the sea level rose rapidly during that time period.From 9.3 7.7 kyr BP,the benthic foraminiferal assemblage was dominated by high percentage of A.compressiscula,suggesting that the sea level was relatively stable.An obvious transition of benthic foraminifera,from the A.compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage,occurred between 7.7 6.2 kyr BP,possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene.This transition may correspond to the gradually strengthened Yellow Sea warm current(YSWC)and finally is established the modern-type circulation in the Yellow Sea.It may also mark the formation of the Yellow Sea cold bottom water(YSCBW)during that period.Since then,the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species,A.ketienziensis,Astrononion italicum and Hanzawaia nipponica,at 6.2 4 kyr BP.A non-deposition period occurred since 4 kyr BP,which possibly related to the hydrology changes caused by the East Asia monsoon.The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression.
