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中国东部沿海平原第四系层序类型
  • 期刊名称:海洋地质与第四纪地质
  • 时间:0
  • 页码:39-51
  • 语言:中文
  • 分类:P736.2[天文地球—海洋地质;天文地球—海洋科学]
  • 作者机构:[1]南京地质矿产研究所,南京210016, [2]天津地质矿产研究所,天津300170
  • 相关基金:中国地质调查局“江苏1:5万扬中市、江都市、谏壁镇、泰州市幅区调”项目(1212010781020);国家自然科学基金项目(40872107).致谢:同济大学海洋与地球科学学院李从先教授对图件修订进行重要指导,中国科学院南京地理与湖泊研究所湖泊沉积与环境重点实验室完成^14C测年,南京地质矿产研究所劳金秀、马雪同志参加部分野外工作,在此一并致谢.
  • 相关项目:海兴新近纪洪泛-火山-海侵层序对构造气候旋回的响应
作者: 李从先|王强|
中文摘要:

江苏省江都地区南北向6个钻孔研究表明,晚更新世晚期(包括MIS3阶段)长江三角洲镇江(大港)江都河段为辫状河道沉积,末次盛冰期由于全球性海面下降形成下切河谷。冰后期海平面上升引发的海侵造成古河谷的充填,并依次形成河床相、河漫滩相、河口湾相及三角洲相。冰后期早期的河床相黄色含砾砂层在该河段均有分布,可以作为标志层,其底板可作为冰后期末次盛冰期的界面。古河谷中部冰后期与末次盛冰期地层具有连续沉积的特征,表明末次冰期低海面时长江仍为入海河流。冰后期海侵大约在9kaBP到达本区;最大海侵发生在6.5~7.0kaBP,此时三角洲已开始发生进积作用,河口沙坝也同时开始形成。三角洲平原形成以后,区域构造运动影响了河谷的均衡调整,密集的入江水道及人类活动不断改变三角洲平原的微地貌景观。

英文摘要:

The study of a total of six drilling holes located in N-S direction in Jiangdu area,Jiangsu Province reveals that there occurred braided fluvial sediments in the Zhenjiang(Dagang)-Jiangdu segment of the Yangtze River,deposited during late Late Pleistocene including Marine Isotope Stage ( MIS) 3.. In the last glacial maximum, the global sea level dropped dramaticly, and an incised-river channel was formed in Zhenjiang-Jiangdu area. The post-glacial transgression caused by sea level rise led to the channel filling and the formation of the sequence from the river channel to floodplain,estuary and deltaic facies in a succession up- wards. Yellow gravelly sands deposited in early post-glacial stage was distributed extensively in the channel,and may he used as a marker. Furthermore,the bottom of the bed may also be used as the boundary of post-glacial and last glacial maximum stags. The continuity of the channel sequence indicates that the Yangtze River was still a running river pouring into the sea in the low stand phase of sea level change during the last glacial stage. The post-glacial transgression arrived here about 9 kaBP and the maximum transgression appeared about 6.5-7.0 kaBP when deltaic progradation started and a channel mouth bar formed syn- chronously. After the deltaic plain formed, the isostatic adjustment of the ancient channel happened under the influence of regional tectonic movement. The miero-geomorphologic landscape of the deltaic plain depends upon the frequent shifting of the distributaries of the Yangtze River and human activities.

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