地理研究 ›› 2018, Vol. 37 ›› Issue (2): 433-446.doi: 10.11821/dlyj201802015

• 研究论文 • 上一篇    

苏北平原龙冈LG孔晚第四纪地层与环境演化记录

夏非1(), 张永战2()   

  1. 1. 江苏第二师范学院城市与资源环境学院,南京 210013
    2. 海岸与海岛开发教育部重点实验室(南京大学),南京 210023
  • 收稿日期:2017-08-02 修回日期:2017-11-29 出版日期:2018-02-20 发布日期:2018-03-10
  • 作者简介:

    作者简介:夏非(1985- ),男,江苏南京人,博士,讲师,主要从事河海交互作用与沉积环境演化研究。E-mail: njuxiafei1985@yahoo.com

  • 基金资助:
    国家重大科学研究计划项目(2013CB956500);江苏省自然科学基金重点项目(BK20130056);国土资源部公益性行业科研专项(201011019);江苏第二师范学院引进人才科研启动经费(919801)

Late Quaternary strata and environmental evolution record of core LG in Longgang, north Jiangsu plain, China

Fei XIA1(), Yongzhan ZHANG2()   

  1. 1. School of Urban and Resource Environment, Jiangsu Second Normal University, Nanjing 210013, China
    2. The Key Laboratory of Coast and Island Development of Ministry of Education (Nanjing University), Nanjing 210023, China
  • Received:2017-08-02 Revised:2017-11-29 Online:2018-02-20 Published:2018-03-10
  • About author:

    Author: Shi Zhenqin (1988-), PhD, specialized in regional development and land space management in mountain areas. E-mail: kevinszq@163.com

    *Corresponding author: Deng Wei (1957-), Professor, specialized in mountain environment and regional development.

    E-mail: dengwei@imde.ac.cn

摘要:

通过研究已经获得的苏北平原龙冈LG孔岩芯野外描述、照片、粒度、14C测年、有孔虫、孢粉、重矿物等原始测试分析数据,并参考邻区发表成果和该区新近补充的资料数据,再分析和讨论了LG孔的地层层序、年代框架和环境演化记录等内容。结果表明:① LG孔34.8 m岩芯保存了MIS 4以来沉积环境演化记录,先后经历了河漫滩、河湖相洪泛平原(第二硬黏土层)、较开放潮滩的潮间带和潮下带、较开放潮滩的潮下带、较开放潮滩的潮间带和潮上带下部、河湖相洪泛平原(第一硬黏土层)、潮上带滨海沼泽和海岸沙堤等一系列环境演化过程,其中潮滩环境的MIS 3海侵层发育;② 西冈贝壳沙堤龙冈段的全新统厚度很薄,一般在10 m以内,由于LG孔可见两个硬黏土层,应位于古河间地而非下切古河谷区,且以其第一硬黏土层顶面作为全新统底界更为合理,故原报道该孔全新统厚达25 m难以成立;③ 老于末次冰盛期的常规和加速器14C测年数据皆存在着不同程度的误差和不确定性,加之淤泥和钙质结核等测年材料易受污染等,故LG孔第二硬黏土层中的2个14C测年数据明显偏年轻,皆不宜用于解释地层年代。

关键词: 苏北平原, 晚第四纪地层, 环境演化, 贝壳沙堤, 硬黏土层, MIS 3海侵层

Abstract:

Original experimental analysis results, including field descriptions, photos, grain size, 14C dating, foraminifera, pollens and heavy minerals, of core LG sediments in Longgang, north Jiangsu plain of China, were acquired by predecessors in the 1980s. Based on studies on these data, plus referring to published results of adjacent area and new data in the study area, a reinterpretation of stratigraphic sequence, chronological framework and environmental evolution record of core LG was presented in this paper. The results showed that, (1) Core LG with a length of 34.8 m preserved the sedimentary environment evolution since Marine Isotope Stage 4 (MIS 4); this study area has undergone a progression of regional sedimentary environments (i.e., river overbank, fluvial and lacustrine floodplain (the second stiff mud layer), intertidal and subtidal zone of relatively open tidal flat, subtidal zone of relatively open tidal flat, intertidal and lower part of supratidal zone of relatively open tidal flat, fluvial and lacustrine floodplain (the first stiff mud layer), coastal marsh in the supratidal zone, and chenier); the MIS 3 transgressive layer with tidal flat facies was well developed in this core; (2) The thickness of Holocene strata in the Longgang section of Xigang chenier is quite small and commonly less than 10 m; due to the fact that core LG has two stiff mud layers, the core should be located in paleointerfluves rather than in paleovalleys, and it is more logical that the top surface of the first stiff mud layer is regarded as the base of Holocene strata, furthermore, it is impossible that its Holocene strata reached 25 m in thickness which the original researchers argued; (3) Since all of the conventional and AMS 14C dating results which are older than the Last Glacial Maximum have errors and uncertainties with different levels, and dating materials for mud and calcareous concretions are prone to be contaminated, the two 14C dating results in the second stiff mud layer of core LG are younger than the real age obviously and could not be adopted to interpret the strata age.

Key words: north Jiangsu plain, Late Quaternary strata, environmental evolution, chenier, stiff mud layer, MIS 3 transgressive layer