摘要
本文通过嘉陵江广元段卫星影像的解译和野外地质地貌调查,将该地区的地貌分为河流冲积平原、低山丘陵和基岩山区三种类型,并统一划分出河流T1、T2、T3级阶地,阶地堆积以典型的河流二元结构为主,砾石的磨圆度和分选性较好。该地区第四纪地层厚度一般小于32 m,其中T1阶地第四纪地层厚度较大,主要分布在15~32 m范围内,而T2、T3阶地为基座基底,上覆第四系不甚发育,T2第四纪地层厚度小于15 m,T3阶地厚度小于5 m。该地区河流阶地的物质组成、地层厚度及分布特征,与龙门山构造活动强烈地区的河流阶地堆积差别较为明显,显示出嘉陵江广元段河流下切作用较弱,沉积相比较单一稳定,这表明这一地区的河流堆积主要受到气候因素影响,与这一地区微弱的构造活动背景也较为吻合。
According to the interpretation of satellite images and field geological survey,the landforms in this area can be divided into three types： fluvial plain,hill region and bedrock mountain terrain. The river terrace is divided to T1,T2,and T3.,Tthe deposition of terraces is dominated by dual structure,and the roundness and sorting of gravels are better. The thickness of the Quaternary is less than 32 m,the thickness of T1 mainly distributed in the range of 15 - 32 m. Because of the base substrate,the overlying Quaternary rarely developed in T1 and T2.,T the thickness of T2 and T3 is less than 15 m and 5m respectively. The characteristics of composition and distribution of river terraces in this area are obviously different with those in the Longmenshan mountain. These,showing that the down cutting in the Guangyuan section of the Jjialing Rriver is weak and the sedimentary facies is single and stable.The results indicate that the fluvial deposit is mainly affected by the climate factors,and which is consistent with the weak activity structure background in this area.
出处
《四川地震》
2017年第3期19-24,42,共7页
Earthquake Research in Sichuan
