长江口北支中全新世以来环境演变变异事件及影响因素

对崇明岛北侧的永隆沙钻孔进行了系统的采样和粒度、微体古生物、环境磁学以及C^14测年等分析，大致恢复了长江口北支古地理环境演变的过程。通过环境磁学和微体古生物分析，揭示了在2080～2000、700～625aBP这两段历史时期，长江口北支表现为河口沙坝亚环境和河口河槽亚环境。这两次环境变异事件记录了长江主泓南北迁移的事实。长江河道的变迁受到诸多因素的影响，科氏力的作用是长江口不断南偏这一发展总趋势的主要原因，海平面上升与气候的变化则是长江主泓南北摆动的主要影响因素。

Environmental Evolution of the North Branch of the Yangtze River(Changjiang River)Estuary Since Middle Holocene

Research work on the systematic sampling from the profile of the CY core that lies in the north of the Chongming Island has been carried out. Based on comprehensive analyses of grain size, magnetic characters, microfossils (such as foraminifer) and 14 C dating, we tried to reconstruct the paleo geographic environmental evolution of the north branch of the Yangtze River estuary. During 2 080~2 000 aBP and 700~625 aBP periods, the north branch was respectively subject to estuarine sandbar and scoured riverbed sub environments. These two events recorded the migrations of the Yangtze River channel, which were affected by many factors. The migration to the south of the Yangtze River channel was mainly controlled by the Coriolis force, and the swing to the south or to the north of the main channel was mainly influenced by the sea level rise and climatic changes.