长江江苏段末次盛冰期古河槽特征  

Characteristics of the Yangtze River Paleo-valley in Jiangsu Province in the Last Glacial Maximum

作　　者：曹光杰[1,2] 爨景波[1] 李彦彦[2] 

机构地区：[1]临沂大学实验中心,山东临沂276005 [2]南京师范大学地理科学学院,江苏南京210046

出　　处：《地理科学》2012年第8期986-992,共7页Scientia Geographica Sinica

基　　金：国家自然科学基金项目(40871010;41072138);国家重点基础研究发展规划项目(2003CB415201-8)资助

摘　　要：选择长江江苏段作为研究河段,根据南京长江三桥、长江大桥、长江四桥、润扬长江大桥、扬中长江大桥、江阴长江大桥、苏通长江大桥7个断面的285个地质勘探钻孔资料及参考文献中的8个钻孔资料,建立了7个长江古河谷地质剖面图。在拟建南京长江四桥附近、扬中长江大桥附近的7个钻孔进行了采样分析,获得了8个14C年代、1个ESR年代数据。通过分析发现,末次盛冰期长江古河槽镇江以上切割到基岩,镇江以下嵌在老河床相沉积层上,河槽在南京下关-栖霞山段形成局部深切;南京段约-63 m以下的河槽为末次盛冰期的古河槽,相对狭窄陡峭,宽深比较小,向下游宽深比逐渐变大,扬中以下形成分叉河道体系;古河槽中自下而上充填了从粗到细的沉积旋回,河床相沉积物向下游逐渐变细。The section of Yangtze River in Jiangsu Province was selected as the research reach. Seven cross-sections of paleo-valley depositional sequences were established with 285 bore datum and 8 documents from the references, which were the NO.3, NO.1, NO.4 Nanjing Yangtze River Bridges, the Runyang Yangtze River Bridge, the Yangzhong Yangtze River Bridge, the Jiangyin Yangtze River Bridge and the Sutong Yangtze River Bridge. 8 age results of ~4C and 1 age results of ESR were obtained through analysis of seven drilling cores samples near the Nanjing NO.4 Bridge and the Yangzhong Bridge. The results indicate that, in the Last Glacial Maximum （LGM）, the incised-valley was cut down into bedrocks at the upper reach of Zhenjiang Province, and the paleo-channel of Yangtze River flows through old riverbed sedimentary facies at the down reach of Zhenjiang Province, and the paleo-valley formed partly deep cut in the Xiaguan-Qixia Mountain. The deep in- cised-valley at the depth of-63 m to-94 m was the Yangtze River valley during the LGM, the deep in- cised-valley channel was narrow and the river flowed swiftly at Nanjing reach. The width to depth ratio （ -d--B/H ）at Nanjing reach was small than that at Zhenjiang reach, which gradually increased along down- stream. The bifurcation paleo-valley system of the Yangtze River were formed below Yangzhong. It is also found that the sediments of the paleo-valley in Jiangsu reach consist of an obvious rhythm from graver and coarse sand to fine sand from bottom to top and the sedimentation was gradually fined along downstream.

关 键 词：长江江苏段 末次盛冰期 长江古河槽 地质剖面 

分 类 号：P512[天文地球—地质学] P534