末次冰消期以来辽东半岛东南近岸泥质区的古环境演化  

PALEO-ENVIRONMENTAL EVOLUTION IN THE SOUTHEAST COASTAL MUD AREA OFF LIAODONG PENINSULA SINCE THE LAST DEGLACIATION

作　　者：陈晓辉[1,2] 李日辉[1,2] 孙荣涛[3] 王燕[1,2] 蓝先洪[1,2] 

机构地区：[1]国土资源部海洋油气资源与环境地质重点实验室,青岛266071 [2]青岛海洋地质研究所,青岛266071 [3]山东理工大学资源与环境工程学院,淄博255049

出　　处：《第四纪研究》2016年第6期1489-1501,共13页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41406077）和国土资源部中国地质大调查项目（批准号：1212011220113、GZH200800501、GZH201500203和GZH201400205）共同资助

摘　　要：辽东半岛东南近岸泥质区是北黄海全新世高海面以来的沉积中心之一，末次冰盛期以来，随着海平面的阶梯式上升在该区域形成了特征的沉积地层，这些地层是研究陆架区沉积环境演化与事件沉积的良好载体。本文通过对取自辽东半岛东南近岸泥质区4个柱状岩芯的岩性、微体古生物以及AMS 14C年代学的分析，探讨了研究区末次冰消期以来的沉积环境演化。研究表明，辽东半岛东南近岸泥质区末次冰消期以来的沉积环境演化与海平面变化存在良好的对应关系，具有明显的阶段性特征：末次冰消期至约10396cal.a B.P.期间的低海面沉积阶段对应海水尚未到达研究区的河流沉积环境；海水自约10396cal.a B.P.开始侵入研究区，海平面变化在-43^-47m，海水在此停滞徘徊了近千年，对应代表陆海沉积发生转换的盐沼沉积环境；随着海平面的逐渐上升，形成了全新世以来的沉积地层，自下而上可划分为约10369~6778cal.a B.P.海平面上升期间和约6778cal.a B.P.高海面以来两个沉积阶段，分别对应潮流作用下的潮坪-滨海沉积环境和沿岸流及黄海暖流为主的环流体系影响下的浅海沉积环境。研究区泥炭层的AMS 14C日历年龄介于约10396~10369cal.a B.P.之间，与Younger Dryas事件在北黄海响应的泥炭层或硬质粘土层为不同时期的沉积，与发生在末次冰消期以来两次融水脉冲事件MWP-1B（11.6~11.3cal.a B.P.）与MWP-1C（9.9~9.0cal.a B.P.）之间海平面缓慢上升期相吻合，表明北黄海这一时期泥炭层的形成可能与两次融水脉冲事件期间的海平面变化过程密切相关，可作为这一海平面事件在北黄海陆架响应的一个重要证据。而这一时期泥炭层的出现表明北黄海这一海平面缓慢上升过程中存在停滞阶段。截至目前，这一海平面变化过程的响应沉积在中国东部其他陆架海区证据相对较少，有待进步一The southeast coastal mud area off Liaodong Peninsula was considered as one of depositional centers during the Holocene.During and since the Last Deglaciation （LD）,some specific deposits related to the sea level step-rise were deposited in this area,which carries abundant information on the sedimentary environmental evolution and geological events.Four piston cores （DZ-1：38°50.65＇N,121°57.02＇E;DZ-4：38°54.61＇N,122°08.51＇E;DZ-5：38°58.40＇N,122°16.76＇E;DZ-7：39°04.40＇N,122°24.22＇E） drilled in the southeast coastal mud area off Liaodong Peninsula were split and described in detail before sampling.In order to reveal the paleo-environmental evolution in the study area since LD,233 sediment samples at about 4cm intervals in the four cores were collected for microfossils analysis and 8 samples （including 4 benthic foraminifera samples and 4 peat layer samples） for AMS 14C dating.The results suggest that the study area has experienced multistage sedimentary environmental changes （Stage Ⅲ,Stage Ⅱ and Stage Ⅰ） in response to different sea-level regimes since LD.Stage Ⅲ（during the sea-level lowstand period from the LD to ca.10396cal.a B.P.）,mainly characterized by yellowish brown fine sand with no microfossils,corresponds to fluvial environment without the influence of the sea.The seawater arrived at the study area since ca.10396cal.a B.P.,and two stages （Stage Ⅱ and Stage Ⅰ） of Holocene deposits were formed from then on.Stage Ⅱ（during the sea-level rise period from ca.10396cal.a B.P.to 6778cal.a B.P.）,started as a peat layer （during the period from ca.10396cal.a B.P.to ca.10369cal.a B.P.） with almost absent microfossils,corresponding to salt marsh environment showing a transition from a continental facies to a marine one,and followed by the deposits composed of yellowish brown clay to gray-brown clay from the bottom up.The benthic foraminiferal assemblages in the later section are dominated in the lower part by brackish water species including Rosal

关 键 词：末次冰消期 辽东半岛东南近岸泥质区 泥炭层 融水脉冲事件 沉积环境 

分 类 号：P722.5[天文地球—海洋科学] P736