%0 Journal Article
%T Geomorphic Features and Origin of the Valley Bottom Troughs at the Site of Three Gorges Dam<br>长江三峡坝区河谷深槽的地貌特征及其成因
%A YANG Dayuan
%A LI Xusheng
%A KE Xiankun
%A ZHOU Lufu
%A CHEN Deji
%A YANG Tianmin
%A XUE Guofu
%A <br>杨达源
%A 李徐生
%A 柯贤坤
%A 周旅复
%A 陈德基
%A 杨天民
%A 薛果夫
%J 地理学报
%D 2002
%I 
%X This paper describes valley bottom troughs of the Changjiang River and infers the geomorphological development of troughs. Based on the morphology of the troughs, the following conclusions are drawn. (1) The deep troughs on the Three Gorges valley bottom are formed by river downcutting along the structurally zones on the background of regional tectonic uplift. The data of 14C dating indicate that the downcutting of the troughs occurred at about 40-30 ka BP. (2) When river downcutting occurred in the river bed of Changjiang, the jets current with a large number of pebbles, ground and eroded the valley bottom, resulting in trough formation and deepening. Meanwhile, water currents with gravels and pebbles eroded the bank and the left wall of No.76 trough as well as the right wall of No.77 trough by striking, scouring, horizontal and vertical grinding. The left wall of No.77 trough was developed after trough deepening, when the pressure-released fracture formed on trough bank and hence induced collapse of the wall under the water. (3) The trend of the troughs is controlled by longitudinal structural fissures. The deepest points of the troughs are normally located at the intersection of the longitudinal fissures with the transverse ones. The depth of the trough is mainly determined by the intensity of the water current and the consistency of bedrock against erosion, of which the trough is composed, and is not controlled by the altitude of the sea level as the base level.
%K valley bottom trough
%K geomorphologic feature of valley
%K the Three Gorges<br>长江
%K 成因
%K 河谷深槽
%K 谷底
%K 地貌特征
%K 三峡坝区
%K 抗蚀强度
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=869B153A4C6B5B85&jid=F7B5B947C24B9D649491012214E4BEF4&aid=E5A5F47B9F7E50E0&yid=C3ACC247184A22C1&vid=11B4E5CC8CDD3201&iid=94C357A881DFC066&sid=4002B7787911C73B&eid=385E3C2062167B88&journal_id=0375-5444&journal_name=地理学报&referenced_num=9&reference_num=11