沉积学报2012，Vol.30Issue(5)：879-890,12.
渤海湾西北岸埋藏牡蛎礁礁顶上下沉积物中硅藻对“礁泥转换”古沉积环境的重建
Diatom Analysis in the Top and Bottom Muddy Sediments of Buried Oyster Reef for the Reef Mud Conversion Palaeoenvironmental Reconstruction, Northwest Bohai Bay
摘要
Abstract
Dawuzhuang oyster reef is the deeply studied one in the recent years while Konggang oyster reef is a new one on the northwest coast of Bohai Bay. Diatom analysis of the muddy sediments filling into the oyster shells, be- tween the shells and in the overlying muddy layers all contained the Auliscus caelatus which indicated that the late de- velopment of the reef and the early stage of the overlying muddy layers are all belonging to the intertidal zone environ- ment. However, the reef-mud conversion was not the same in these two reefs. (1) The Auliseus caelatus in Dawuzhuang oyster reef decreased gradually from the top of the reef to the overlying muddy layers, which indicated an environment change from the middle to upper parts of intertidal zone, upper parts of intertidal zone to supratidal zone. (2) The Achnanches brevipes, indicating estuary environment, with the percentage of 6% -23% were found only in the overlying muddy layers of Konggang oyseter reef. It showed estuary influence in the muddy layers. The above differences revealed the reef-mud conversion was not the same in the two reefs. The Dawuzhuang oyster reef grew up to the middle to upper parts of intertidal zone in the year 5 520 eal BP, and development stopped with the gradual dis- appearance of the marine influence. The Konggang oyster reef grew up to the intertidal zone in the year 4 000 cal BP and was suddenly buried by the muddy and sandy sediments which maybe from the Yellow River. Therefore, the "reef-mud conversion" periods, which the oyster reefs stopped growing up and began overlaid by the mud layers, are 5 520 cal BP and 4 000 cal BP in Dawuzhuang and Tianjin Konggang, respectively. The seawater didnl quickly exit when the two reefs stop growing, and then 1.2m thick intertidal zone sediments and 2.9 thick la- goon-intertidal zone sediments respectively deposited in the two locations. The author speculated that the seawater completely withdraw from the two reefs were later than 4 700 and 1 100 years ago. The altitudes of the maximum ma- rine layers are -1.44 m in Dawuzhuang and 0m in Konggang profiles. It was speculated that the relative sea level were 2.95 m under the modem sea level in 4 700a ago and 1.5m under the modem sea level in 1 100a ago. This is due to the crest decline and compaction which indicated that the earlier of the regression, the lower position of the up- per limit of the marine layer in the west Bohai Bay. The ancient Yellow River diverged and into the sea from Tianjin in 4 000 years ago. At the same time, the large number of the sediments into the sea and made the coastline constantly advanced seaward which lead to the subsequent oyster reefs developed seaward.关键词
渤海湾西北岸/大吴庄牡蛎礁/空港物流中心牡蛎礁/硅藻分析/潮间带Key words
northwest Bohai Bay/oyster reef in Dawuzhuang/oyster reef in Konggang/diatom analysis/intertidalzone分类
天文与地球科学引用本文复制引用
方晶,王宏,王福,商志文,胡克,杨永强,范昌福,王海峰..渤海湾西北岸埋藏牡蛎礁礁顶上下沉积物中硅藻对“礁泥转换”古沉积环境的重建[J].沉积学报,2012,30(5):879-890,12.基金项目
国家自然科学基金项目（批准号：40872106）和中国地质调查局项目（编号：1212010911069）资助. （）
