岷江上游第四纪叠溪古堰塞湖的演化

Evolution of a dammed paleolake in the Quaternary Diexi basin in the upper reaches of the Minjiang River,Sichuan,China.

采用岩性相和沉积体系的分析方法对岷江上游流域的阶地进行了研究,发现叠溪较场到太平村以北约28 km的沿江河段内断续分布有湖相沉积。对太平村一带的三级阶地沉积识别出冲积扇沉积体系、湖泊沉积体系、河流沉积体系和风成、表生沉积体系。认为古堰塞湖发育2期高湖平面,其间存在低湖面期形成的古土壤层。根据最高湖泊沉积与堵江滑坡体的顶部高度对比和堰塞湖发育的时间计算,太平村地区相对叠溪校场地区存在着平均3.18 m/ka的抬升运动。

The authors use the analytical method of lithofacies and sedimentary systems to study the river terraces in the upper reaches of the Minjiang River and find that lacustrine sediments are distributed discontinuously along a -28 km long river stretch from Diexi to north of Taiping ViLlage. The fluvial sedimentary system, lacustrine sedimentary system, alluvial fan sedimentary system and eolian and supergene sedimentary system are recognized in terrace III in the vicinity of Taiping Village. Two stages of high lake levels have occurred in a dammed paleolake and between the two stages there have occurred paleosols formed in the stage of the low lake level. According to a comparison between the altitude of the highest lacustrine sediments and that of the top of the landslide mass which have blocked the river and the time of dammed lake development, the authors conclude that the Taiping ViLlage area, relative to the Diexi area, has been uplifted at an average rate of 3.18 m/ka.