BT113孔和BT114孔是位于渤海湾西岸地区的2个80 m全取心钻孔.通过对钻孔岩心的岩性、沉积构造及生物组合等特征分析,结合AMS14C和OSL(光释光)测年结果,揭示中更新世晚期以来本地区主要发育3个海相地层:自下而上为中更新统上部的第三海相地层(简称“海三”)、上更新统的第二海相地层(简称“海二”)和全新统的第一海相地层(简称“海一”),指示中更新世晚期以来研究区发生的3次主要海面波动.与全球海面变化曲线对比,海三,海二和海一分别发育于MIS(深海氧同位素阶段)7、MIS5和MIS1的高海面时期,说明渤海湾西岸中更新晚期以来地层记录的海面变化趋势与全球变化一致.与前人的传统认识不同,认为受全球海面及渤海海峡地貌共同影响,MIS3时期研究区并未发生大范围海侵.通过多个钻孔的对比分析,3个海相地层在渤海湾西岸地区的分布较广,具有良好的可对比性,不同钻孔之间同一海相地层的高程和厚度的较大差异指示本地区在晚更新世期间发生较强的差异性沉降活动.%Two 80 meters deep boreholes (BT113 and BT114) were carried in the west coast of Bohai Bay in order to clarify the revolution of sedimentary environments. Three marine sedimentary beds were identified based on sediment composition and texture, faunal assemblages ( mollusk, benthic foraminifera and ostracoda) as well as AMS 14C and OSL ages. According to their order, from bottom to top, they are interpreted as Marine Bed 3 (M3) deposited in the Later Mid-Pleistocene, Marine Bed 2 (M2) in the Late Pleistocene and Marine Bed 1 (Ml) in the Holocene. These marine beds, from M3 to M1, reveal three major sea level movements since the Late Mid-Pleistocene. M3, M2 and M1, corresponding to marine facies deposited in MIS (marine isotope stage) 7, MIS5, and MIS1, respectively, indicate the repeated highstands during those periods. Therefore, it can be conclude that the development of these marine beds recording the regional sea level trends in the west coast of Bohai Bay, is well accordant with the global change. Different from the previous studies, authors consider that the marine transgression which controlled sea water to intrude into the Bohai Sea did not impact thernstudied area during MIS3 due to the relative lowstand and shallow topography of Bohai Strait. Contrastive analysis of multi boreholes indicates that the three marine beds are distributed widely and comparable well in the west coast of Bohai Bay. Changeable elevation and thickness of the marine beds within different boreholes imply that there have happened differential depressional movements during the Late Pleistocene period.
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