临沂九曲沂河大桥附近沂河古河槽特征

选择临沂九曲沂河大桥附近沂河断面作为研究剖面.根据九曲沂河大桥的地质勘探钻孔资料,绘制了沂河古河槽地质剖面示意图.沿勘探钻孔进行了浅层地震影像法物探.在下游的G327沂河大桥附近河槽底部和上游约3 km枋河右岸的埋藏阶地上采集了年代样品,获得了1个光释光年代、2个14 C年代.结论认为:沂河古河槽底部断裂带、裂隙发育;九曲沂河大桥附近约53～55 m以下河槽为末次盛冰期时沂河、祊河的古河槽,当时枋河在九曲沂河大桥的下游汇入沂河;约54 m以上为晚冰期以来沂河河槽,晚冰期以后,枋河约在现在入沂河的位置注入沂河.由于河槽宽浅,流量季节变化大,形成分汉-辫状河特征.

The Paleo-valley near the Jiuquyihe River Bridge of Linyi, Shandong Province, China

The stratigraphical cross-section near the Jiuquyihe River Bridge of Linyi City, Shandong Province, China was selected as the research zone. The stratigraphical cross-sections of paleo-valley were established with bore datum near Jiuquyihe River Bridge. The geophysical seismic imaging method of shallow stratigraphy was applied to detect drilling. Data of one OSL dating was obtained through the analysis of the sample from the paleo-valley bottom near the G327 Yihe River Bridge and of two ¹⁴C dating were obtained through analysis of samples in burial terrace of the Benghe River. It is concluded that the Yihe River''s paleo-valley is located on the fault zone. In the Last Glacial Maximum, the paleo-valley of the Yihe River and the Benghe River lay 53-55 m below and near the Jiuquyi River Bridge. During the Last Glacial Maximum, the Benghe River flowed into the Yihe River in the downstream of the Jiuquyihe River Bridge. The paleo-valley of the Yihe River lay 54 m above the Late Glacial. After the Late Glacial, the Benghe River flowed into the Yihe River at the present location. The Yihe River''s paleo-valley has a relatively large width-depth ratio which means a wide and shallow river channel, with the characteristics of braided river.