滦河口北部七里海地区中晚全新世沉积演化过程

滦河口北部七里海地区全新世演化过程是划分滦河三角洲范围的依据，也是认识陆海相互作用的有益补充。通过对七里海地区6个钻孔进行详细的沉积学、微体古生物研究和年代测定，分析了中晚全新世以来的沉积环境演化过程。滦河口北部七里海地区发育中晚全新世冲积扇-湖相三角洲、晚全新世砂坝-潟湖和海相三角洲及近现代砂坝-潟湖地貌沉积体系。6~5 ka B.P.，七里海西部发育冲积扇湖相三角洲沉积体系，东部为湖相三角洲前缘。5~1 ka B.P.，七里海南部形成潟湖，推断现今海岸线外侧发育一道滨海砂坝，区域形成第一期砂坝-潟湖地貌沉积体系。10~19世纪，区域受滦河泛滥的影响，逐渐成陆，发育潟湖-潮上带-分支河道的三角洲沉积组合。19世纪，第一期砂坝-潟湖地貌沉积体系中砂坝不断向陆迁移至翡翠岛，七里海地区形成浅水湖沼。1883年，滦河洪水在七里海新开口冲破海岸沙丘，形成七里海潟湖，区域形成现今砂坝-潟湖地貌沉积体系。1915年，滦河冲开翡翠岛南部沙丘入海，发育现代三角洲。

Mid-Late Holocene sedimentary evolution process in the Qilihai area,northern Luanhe Estuary

The Holocene evolution process of the Qilihai area in the northern part of the Luanhe Estuary is the basis for division of the Luanhe River Delta.It is also a useful addition to understanding the interaction between land and sea.Detailed sedimentology, microfossils (foraminifera and ostracods), of six boreholes in the study area were analyzed, combined with 14C dating, to reveal the Late Holocene sedimentary environment evolution.In the Qilihai area, the lacustrine delta-alluvial fan was developed in the Mid-Late Holocene.The barrier-lagoon geomorphology depositional system and Marine delta were developed in the Late Holocene.The barrier-lagoon geomorphology depositional system was developed in present. 6~5 ka B.P., the alluvial fan and the lacustrine delta developed in the west, and the lacustrine delta front was developed in the east. 5~1 ka B.P., the first barrier-lagoon geomorphology depositional system was developed to form lagoon in the southern and sand barrier in the outside of the present coastline. From 19th century to 10th century, delta depositional system comprised of lagoon, supratidal zone and branch channel was formed as flooding of the Luanhe River.In 19th century, with the migration of first barrier-lagoon geomorphology depositional system landward to the Feicui Island, a shallow lake was developed in the Qilihai area.In 1883, a crevasse was developed in coastal sand dunes as the action of Luanhe River floods, and then the Qilihai lagoon was formed as the seawater flowing backward, which resulted in the formation of the current barrier-lagoon geomorphology depositional system.In 1915, the Luanhe River burst through the sand dunes south of the Emerald Island into the sea, forming the current delta.