摘要
河流阶地详细记录了区域构造活动和地貌演化信息,可为第四纪地貌阶段性隆升提供证据。位于四川大凉山区的昭觉河流域及其支流地处青藏高原东南部,横断山脉与四川盆地西南缘的过渡带,发育了河流阶地等层状地貌。以昭觉河的支流比尔河为研究对象,通过野外河流阶地级序及阶地沉积物调查,结合14C测年结果,厘定了比尔河的3级河流阶地,其中T_(2)和T_(3)为基座阶地,T1为堆积阶地,形成时间为27.75 ka B.P.、12.20 ka B.P.以及6.65 ka B.P.,其中T3阶地与T2阶地的河流下切速率分别为0.59~1.29 mm/a和1.26~4.50 mm/a。认为川西大凉山地区30 000 a以来地貌至少经历了2次间歇性抬升,在整体隆升过程中,河流上游较中下游的地壳抬升速度更快,具有掀斜式抬升特征。T_(3)、T_(2)、T_(1)阶地的形成与研究区气候变化有一定相关性,但新构造运动是比尔河河流阶地形成的主导因素,这对了解川西地区晚更新世以来河流阶地的级序展布及演化具有重要意义。
The detailed information of regional active structures and geomorphic evolution were recorded by river terraces,which can provide evidence for the phased uplift of the Quaternary geomorphology.Zhaojue River Basin and its tributaries in Daliang Mountain of Sichuan Province are located in the transitional zone between Hengduan Mountains in the southeast of Qinghai-Tibet Plateau and the southwestern edge of Sichuan Basin,with the development of many river terraces and other layered landforms.The authors took a tributary of Zhaojue River-Bier River in the area as a case study to identify the three river terraces of Bier River,through the investigation of the terrace sequences,river alluvial sediments and 14 C dating results.The T_(2) and T_(3) are the rock-seated terraces and T_(1) is a constructional terrace,with formation times of 27.75 ka B.P.,12.20 ka B.P.,and 6.65 ka B.P..The river incision rates of T_(3) and T_(2) are 0.59-1.29 mm/a and 1.26-4.50 mm/a respectively.The landform in the Daliangshan area of Western Sichuan has experienced at least two intermittent uplifts in the past 30000 years,and the crustal uplift rate in the upper reaches of the river is faster than that in the middle and lower reaches of the river during the overall uplift process,with characteristics of tilting uplift.The terraces formation of T_(3),T_(2) and T_(1) has a certain correlation with the climate change in the study area,but the neotectonic activity is the dominant factor in the terraces formation of Bier River,which is of great significance for the river terraces sequence distribution and evolution in Western Sichuan since the Late Pleistocene.
作者
殷志强
屈天月
庞明非
邵海
丁一
YIN Zhiqiang;QU Tianyue;PANG Mingfei;SHAO Hai;DING Yi(China Institute of Geo-environment Monitoring,Beijing 100081,China;Texas A&M University,College Station,Texas 77840,America;China University of Geosciences(Wuhan),Hubei Wuhan 430074,China)
出处
《中国地质调查》
CAS
2023年第2期64-71,共8页
Geological Survey of China
基金
国家自然科学基金“构造差异隆升影响下顺构造地貌发育强度对大型滑坡的控制机理和孕灾模式——以美姑河流域为例(编号:41977258)”项目资助。
关键词
河流阶地
级序
地貌演化
晚更新世
比尔河
river terrace
terrace sequences
geomorphological evolution
Late Pleistocene
Bier River