渤海湾晚更新世晚期以来古河道分布和三角洲发育及其古环境的演变

渤海湾及其沿岸是中国海洋地质与第四纪地质研究程度最高的地区之一。虽然研究成果众多，但仍有一些基础的地质问题亟待解决。比如，晚更新世晚期黄河是否流经渤海湾?全新世黄河在渤海湾及其沿岸形成的多期次三角洲叶瓣在海域如何展布?以上问题一直是中国海洋地质研究中备受关注的热点话题。借助2016-2017年在渤海湾获取的约2000 km的浅地层剖面数据、2个30 m左右的取芯钻孔（BXZK2017-1和BXZK2017-2孔）及相应的AMS ¹⁴C和OSL测年数据，同时结合前人的一些浅剖数据和钻孔的研究成果，将渤海湾中部晚更新世以来的地层自上而下划分出4个地震单元（SU1~SU4）和6个沉积单元（DU1-DU6），分别对应前三角洲相、潮坪与浅海、泛滥平原、河道相、海陆交互相、湖沼相。在此基础上综合探讨渤海湾晚更新世晚期以来总体的地层框架和沉积演化特征。研究表明：黄河可能在21.8~9 cal ka BP，由近东西向流经渤海湾北部进入渤海中部盆地；全新世以来，渤海湾从西北侧至南侧，依次分布4期次的三角洲叶瓣，对应的发育时间可能分别是1400 AD~现在、11~1128 AD、700 BC~11 AD和1855~现在；渤海湾西侧最北两期次的水下三角洲可能主要与海河有关，而南侧其余2期次三角洲叶瓣则可能分别对应岐口超级叶瓣以及现代黄河三角洲超级叶瓣。加深了解渤海湾晚更新世晚期以来的地层序列演化、古河道发育以及全新世三角洲在渤海湾的展布情况，将有助于渤海湾海岸带开发、海底工程建设以及地质灾害防范等。

Paleochannel distribution, delta development and paleoenvironment evolution in Bohai Bay since the Late Pleistocene

The Bohai Bay and its coastal area are one of the most attractive hotspots for the studies of marine geology and Quaternary geology in China. Although many achievements have been made, some fundamental geological questions still remain unsolved. For example, did the Yellow River flow through Bohai Bay during the Late Pleistocene? How was the multi-stage delta lobes of the Yellow River Delta distribute in the Bohai Bay? Those questions have been attracting great attentions from marine geologists in China. Based upon ~2000 km seismic profile data, two ~30m-length boreholes (BHZK2017-1 and BHZK2017-2) in Bohai Bay during 2016-2017, numerous AMS ¹⁴C and OSL dating results and previous achievements of seismic profiles and boreholes, the stratigraphic sequences was divided into four seismic units (SU1-SU4) and six sedimentary units (DU1-DU6) in descending order, namely prodelta, tidal flat, floodplain, river channel, land-sea interaction facies and lacustrine/marsh facies, respectively. The general stratigraphic framework and sedimentary evolution of Bohai Bay since the Late Pleistocene were accordingly analyzed. It is revealed that the Yellow River likely flowed from near the East-West to the central basin of the Bohai Sea through the northern part of the Bohai Bay during 21.8-9 cal ka BP. Moreover, four subaqueous delta lobes distributed from the northwest to the south of the Bohai Bay since the Holocene were formed during 1400 AD-present, 1048-1128 AD, 700 BC-11 AD and 1855-present, respectively. Two northern subaqueous delta lobes were mainly related to the Haihe River, and the other two southern delta lobes were likely to be the Qikou superlobe and the modern Yellow River Delta superlobe respectively. The studies upon the sedimentary evolutions, paleochannel development and the subaqueous delta distribution since the Late Pleistocene would be conducive to the layout of coastal engineering programs and the mitigation of geological hazards in Bohai Bay.