程瑜^1,,
李向前¹,
舒军武²,
赵增玉¹,
张祥云¹,
郭刚¹
1. 江苏省地质调查研究院, 江苏 南京 210018
2. 中国科学院南京地质古生物研究所, 资源地层学与古地理学重点实验室, 江苏 南京 210008

基金项目: 中国地质调查局地质调查项目"特殊地质地貌区填图试点"（批准号：DD20160060）和国家自然科学基金项目（批准号：41371207）共同资助


详细信息

作者简介: 程瑜, 女, 28岁, 工程师, 古气候及古环境研究, E-mail:ftchengyu@msn.com

中图分类号: P535, P534.63

收稿日期:2017-09-22
修回日期:2017-12-21
刊出日期:2018-05-30

The formation and evolution of the Changjiang River delta since last glacial

Cheng Yu^1,,
Li Xiangqian¹,
Shu Junwu²,
Zhao Zengyu¹,
Zhang Xiangyun¹,
Guo Gang¹
1. The Institute of Geological Survey of Jiangsu Province, Nanjing 210018, Jiangsu
2. Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu


MSC: P535, P534.63

--> Received Date: 22 September 2017
Revised Date: 21 December 2017
Publish Date: 30 May 2018


摘要
摘要:通过对长江三角洲泰州地区TZK3钻孔沉积物沉积特征、微体古生物的综合分析，结合系统的高分辨率AMS ¹⁴C、OSL测年，讨论了该地区末次冰期以来沉积环境的演变过程。结果显示，TZK3孔自下而上可分为6个沉积单元：1）MIS 4，砂砾层，不含有孔虫，为河床相；2）MIS 3，粉砂，含有贝壳碎片、小海贝、海相腹足类口盖，为河口相；3）MIS 2，含粘土粉砂，含少量介形虫，为河漫滩相；4）12.1~10.5cal.ka B.P.，粉砂，未见有孔虫，为河床相；5）10.5~6.9 cal.ka B.P.，粉砂，零星见个体非常小的有孔虫，潮汐层理发育，为受潮汐影响的河漫滩；6）6.9~4.3 cal.ka B.P.，粉砂，含有大量有孔虫，为河口砂质沉积。对比研究发现，全新世长江三角洲的最大海泛面时期为6.9 cal.ka B.P.，黄桥砂坝发育的年龄区间为7.6~4.3 cal.ka B.P.，为潮成砂坝，其发育主要受长江径流、河口潮汐流和亚洲季风的影响。
关键词: 长江三角洲/
最大海泛面/
黄桥砂坝/
微体古生物/
沉积环境

Abstract:The core TZK3 is located in the southeast Taizhou City(32°23'N, 120°05'E), the north of Changjiang River delta. The lithology of the core is composed of silt and silty sand. Clay, sand, coarse sand and gravel are also found. In this study, for the upper part of the core(70 m-thick sediment), 50 samples were taken for micro-paleontology test with interval of 1.0~1.5 m, and 8 samples for AMS C-14 and 1 sample OSL dating, respectively.
The results show that the core TZK3 can be divided into 6 sedimentary units from bottom to top:(1) 70.00~46.05 m(MIS 4), the lithology is gray silt, fine sand, coarse sand and gravel, indicating river bed phase. The age is 109.28±8.86 ka in 69.5~69.7 m through OSL dating, showing deposition stage is MIS 4. (2) 46.05~44.99 m(MIS 3), silt with sea shell fragments and shellfish, indicating a weak ocean influence, such as the estuary. The calendar calibration age is 27613 cal.a B.P. in 45.7 m, corresponding to the Gehu transgression. (3) 44.99~43.92 m(MIS 2), the lithology gray-green clay with silt. There is plant debris and a small amount of ostracods in the sediment, such as Ilyocypris bradyi and Ilyocypris sp., suggesting a paleosoil. (4) 43.92~37.95 m, with an age of 12.1~10.5 cal.ka B.P., gray silt and fine sand with horizontal bedding from the river bed. There is shell fragments moving from other place and erosion surface with lower strata. (5) 37.95~29.50 m, with an age of 10.5~6.9 cal.ka B.P., gray silt, fine sand and silt with horizontal bedding. The sediment contains plant debris and foraminifera with small form, such as Ammonia sp., Cribrononion sp., Cribrononion incertum. In this phase, the sea level continued to rise, the transgression rate was higher than the sedimentation rate of the sediments, and the coastline continued to move westward. The study area was covered by floods from the tidal. (6) Whose with the depth of 29.5~0 m, with an age of 6.9~4.3 cal.ka B.P., silt containing a lot of foraminifera, such as Ammonia beccarii/Ammonia tepida Group. Due to the increase in the Asian monsoon and precipitation, the capacity can be enhanced in the upper reaches of the Changjiang River. The sediment accumulation rate accelerated, and the coastline move to the east. The study area began to develop Huangqiao estuary sand dam.
Compared with the records in the Changjiang estuary, the maximum transgression of the Changjiang River delta occurred at 6.9 cal.ka B.P. and the age of the Huangqiao sand bar was developed at 7.6~4.3 cal.ka B.P., which is mainly affected by the Asian monsoon, estuary tide and runoff in the Changjiang River.
Key words:Changjiang River delta/
maximum flooding surface/
Huangqiao sand bar/
micropaleontology/
sedimentary environment



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