渤海湾西岸QX02孔Ⅱ海的识别及OSL年龄  

Identification and OSL ages of the Second Marine Bed in Borehole QX02 along the western coast of Bohai Bay

作　　者：陈永胜[1,2] 王福[1,2,3] 姜兴钰[1,2] 黎伟麒 李建芬[1,2] 商志文[1,2] 

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局泥质海岸带地质环境重点实验室,天津300170 [3]天津地质矿产研究所年轻沉积物测年实验室,天津300170 [4]天津师范大学城市与环境科学学院,天津300378

出　　处：《地质通报》2016年第10期1600-1606,共7页Geological Bulletin of China

基　　金：国家自然科学基金项目(批准号:41476074);中国地质调查局项目(编号:1212011120169;12120113005800)

摘　　要：以渤海湾沿海低地的QX02孔为研究对象,进行了沉积岩石学分析和底栖有孔虫统计,结合加速器质谱^(14)C测年和光释光(optically stimulated luminescence,OSL)测年,探讨了该孔记录的第Ⅱ海相层埋深和形成时代。第Ⅱ海相层厚度11.4m,记录相对海面高度-26.83^-15.43m。AMS^(14)C年龄表明,Ⅱ海形成于MIS 3早期、甚至更早。OSL年代学研究显示,Ⅱ海样品等效剂量离散度较高,并且主要集中在2个区间,计算得到新、老2个年龄阶段。基于OSL测年原理的常规判断,认为较老的83.5~62.6ka阶段系受曝光不充分组分的影响,通常采用较年轻的51.9~39.9ka阶段为QX02孔的Ⅱ海沉积年龄。但是,较老的一组年龄从新的视角,暗示了可能的原始沉积过程及相应的海侵发生时间,因而具有重要的年代学和沉积学意义。Alter^iation of marine and terrestrial sediments from Core QX02 along the western coast of Bohai Bay was recognized us-ing lithological characteristics and quantity of benthic foraminifera analysis. Timing of the second marine bed, 11.4m thick,corre-sponding to a relative sea level of-26.83-15.43m,was determined by both AMS 14C and OSL dating methods. The AMS 14C dates demonstrated that the second marine bed was deposited during the early Marine Isotope Stage 3 and even earlier. Dc distribution of typical sediments from the second marine bed was over-dispersed,and two distinct populations could be observed,which yielded a young age range of 51.9~39.9ka,and an old age range of 83.5~62.6ka, respectively. According to the principle of OSL dating, the old fraction obtained from De distribution was limited by the poorly bleaching and,in turn,the fraction of relative young ages was com-monly adopted. However,it is plausible to have a clue from the cluster of the older ages that there would be an original sedimentary process and a corresponding timing of marine transgression.

关 键 词：OSL测年 第Ⅱ海相层 渤海湾西岸 

分 类 号：P736.223[天文地球—海洋地质]