渤海湾全新世贝壳堤与牡蛎礁:古气候与海面变化

Holocene cheniers and oyster reefs in Bohai Bay:palaeoclimate and sea level changes

讨论了早全新世晚期以来渤海湾西岸贝壳堤平原成堤、西北岸牡蛎礁平原(及毗邻浅海区)建礁过程的同时性特征和气候变化与这一特征之间的关系,以及堤、礁记录的相对海面变化。堤、礁大致同时发育,可分为6期,依次分别被寒冷事件5、4、3、2和1分隔。堤底板前、后缘高差大致对应3m的大潮差、礁顶板大致对应海平面。据二者分别重建了南部贝壳堤平原、北部牡蛎礁平原的相对海面变化:南部自7ka cal BP以来基本与现代海平面等高,小的波动在±1m之间,压实固结作用抵消了中全新世的相对高海面;北部中全新世的相对海平面位置因新构造和固结压实双重下沉作用的影响,已位于现代海平面2～3m以下。

This paper deals with the synchronous characteristics of cheniers existing on the Chenier Plain along the west coast of Bohai Bay and oyster reefs existing on the Oyster Reef Plain of northwest Bohai Bay and its adjacent shallow sea.Approximately,such synchronous processes can be separated into six periods,alternately intercalated with the Holocene cold events of 5,4,3,2 and 1.The vertical range between front-foot and rear-base of the chenier-bottom corresponds to the vertical 3m contemporaneous high tidal range,and the reef top approximately reflects the MSL（mean sea level）.Since 7ka cal BP,the relative sea level trend in the Chenier Plain has been quite similar to the present situation,with possible small fluctuations being less than ±1m.The Mid-Holocene high stand of the relative sea level was offset by sedimentary consolidation.However,under the joint influences of neotectonic subsidence and consolidation,the relative MSL was 2～3m below the present sea level on the Oyster Reef Plain.