ABSTRACT
The results of clayey water electric conductivity and foraminiferal identification test conducted on the borehole CZ80 in the west coast plain of Bohai Bay, combined with the AMS14C dates, CZ80 was divided into eight units from the bottom to the top. Unit I (80–59 m) is the continental sedimentation; Unit II (59–57.6 m) is the first transgression layer of the borehole, presumably the marine intrusion layer formed by seawater influencing the borehole during the MIS3 or MIS5 transgression; Unit III (57.6–32.5 m) is storm surge sedimentation; Unit IV (32.5–12.5 m) is the continental flood plain after sea retreat; Unit V (12.5–11.9 m) is the salt marsh environment with ages 7.7–7.3 ka cal BP; Unit VI (11.9–9.7 m) is the continental flood plain with ages 7.3–6.7 ka cal BP; Unit VII (9.7–6.9 m) is the storm surge sedimentation interspersed with marsh sedimentation with ages 6.7–5.3 ka cal BP; Unit VIII (6.9–0.9 m) is the continental sedimentation. We found significant quantities of foraminifera in Units III and IV with extremely low EC value. It was concluded that the storm surge swept the intertidal and shallow marine foraminifera ashore into the storm surge deposits, and that stable marsh deposits exist in the interstices of storm surges.
