地学前缘 ›› 2016, Vol. 23 ›› Issue (4): 301-309.DOI: 10.13745/j.esf.2016.04.026

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QX01孔记录的渤海湾西岸沿海低地MIS 3晚期以来的河道充填与环境演化

 王福, 李建芬, 陈永胜, 王宏, 方晶   

  1. 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 现代沉积物测年实验室, 天津 300170
    4. 天津师范大学 城市与环境科学学院, 天津 300387
    5. 中国社会科学院 考古研究所, 北京 100710
  • 收稿日期:2015-07-30 修回日期:2015-10-12 出版日期:2016-07-15 发布日期:2016-07-15
  • 作者简介:王福(1979—)，男，博士，副研究员，主要从事海岸带与第四纪地质环境研究。E-mail:wfu@cgs.cn
  • 基金资助:

    国家自然科学基金面上项目(41476074)；中国地质调查局项目(1212011120169)

Paleo environment change and river channel infilling since late MIS 3 recorded by drilling core QX01 from the coastal lowland of Bohai Bay.

 WANG  Fu, LI  Jian-Fen, CHEN  Yong-Qing, WANG  Hong, FANG  Jing   

  1. 1. Tianjin Centre, China Geological Survey, Tianjin 300170, China
    2. Key Laboratory of Muddy Coast Geoenvironment, China Geological Survey, Tianjin 300170, China
    3. Young Sediments Dating Laboratory, Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China
    4. College of Urban and Environmental Science, Tianjin Normal University, Tianjin 300387, China
    5. Institute of Archaeology, Chinese Academy of Social Sciences, Beijing 100710, China
  • Received:2015-07-30 Revised:2015-10-12 Online:2016-07-15 Published:2016-07-15

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摘要：

在渤海湾沿海低地地区获得1个30 m的全取心机械钻孔(QX01孔)，对样品进行了沉积岩石学分析、底栖有孔虫鉴定、硅藻鉴定和粒度分析，结合AMS 14C和OSL测年，重建了研究区晚更新世以来的古河道充填及环境演化过程。结果显示QX01孔自下而上可以分为6段：(1)30~29.72 m，陆相洪泛沉积；(2)29.72~29.4 m，海侵沉积，>43.5 ka BP；(3)29.4~17.7 m，砂质沉积物，河道填充沉积，37.9~29.7 ka；(4)17.7~13.2 m，沉积物由砂质变为黏土质，29.7~8 ka，由河道填充转为浅湖沼环境；(5)13.2~5 m，8~4 ka，全新世海侵沉积，沉积环境由陆相转为海陆过渡相，6 000~5 750 cal BP海侵达到最强，之后逐渐退出该区；(6)5 m以上，洪泛沉积，约1.7 ka至今。沉积环境与海面具有很好的响应，MIS 4或6阶段时，海面较低，河流下切，形成古河道，下切最深处位于现代高程为-24.2 m。MIS3阶段早期时，海面上升，37.9 ka河道开始填充，至29.7 ka填充完成，对应高程为-11.8 m。末次盛冰期至早全新世时为浅湖沼环境，沉积作用停止或速率非常低。随着末次盛冰期的结束，海洋作用增强，进入全新世海侵沉积阶段，8~4 ka cal BP。之后，沉积作用停止，至1.7 ka以来，随着河流作用的不断增强，该区变为河流控制的洪泛沉积为主。同时，发现了两次沉积间断，分别发生在末次盛冰期的低海面时期和4~2 ka时的海水退出、河流沉积尚不充分时期。

关键词: 古河道, 环境演化, 沿海低地, 渤海湾

Abstract:

We used an AMS 14C and OSL dated core (QX01) from the coastal lowland of Bohai Bay to decipher the late Pleistocene paleo environment change and river channel infilling. Sedimentary facies, grain size, large amplitude changes in benthic foraminifers assemblage and diatom assemblage composition indicate that the major environmental changes occurred during the last 40000 years in the study area. The results show that 6 sedimentary stages were identified, which is (1) 3029.72 m: fluvial deposition; (2) 29.7229.4 m: transgression deposition, >43.5 ka; (3) 29.417.7 m: sandy sediments, river channel filling, ~37.929.7 ka; (4) 17.713.2 m: sediments finning from sand to clay, ~29.78 ka, the environments from river channel infilling to swamp; (5) 135 m: 84 ka, Holocene transgression deposits, the environments from fresh water swamp, to brackish swamp or salt mash, to shallow sea, to salt marsh, most strongest marine influence happened during 60005750 cal BP, then retreat; (6) 50 m: since 1.7 ka, the environment was controlled by river, and it is flood plain deposits during this period. The sedimentary changes were correlated with sea level change very well. During MIS 4 or 6, the sea level was relatively lower, the river cut down and river channel formed, then the river channel was infilling during 37.929.7 ka of MIS 3, when the sea level was relatively higher, the height of the river channel were infilled from -24.2 m to -11.8 m of Huanghai 85 highness. Then the last glacial maximum came, the sea water retreated out of Bohai Sea and the study area was swamp or shallow lake; the sedimentation stopped or at a very low level till the early Holocene, 8 ka. With the end of the last glacial maximum, the sea water came back again during 84 ka, represented by fresh swamp, salt marsh, and shallow sea deposits. Then the deposition stopped again, till 1.7 ka, with the role of the river, the environments became floodplain deposits. Moreover, two sedimentary break were identified, which is the break during last glacial of low sea level, and the break during 41.7 ka, when the marine influence finished or sea water retreated from the study area, but the role of the river had not started.

Key words: palaeochannel, environmental change, coastal lowland, Bohai Bay

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