第四纪冰川遗迹的判别标准与方法问题——兼论蒙山巨砾堆积堤之成因

判断中国东部中低山地冰川作用遗迹的真伪,只能通过科学实践检验和学术争鸣加以解决。利用实地考察所测数据资料,证明山东蒙山确无第四纪冰川遗迹。包括蒙山在内的山东中低山丘陵,迄今为止没有发现符合判别标准的末次冰期冰川地貌三要素组合。蒙山兰溪峡谷的谷形指数(0.07~0.24)与世界各地真正的冰川槽谷不符,被当作冰川证据的蒙山兰溪峡谷谷壁擦痕和拦马墙巨砾堆积堤砾石擦痕,不具有作为冰川地貌证据的唯一性或专属性,而是砾石沿河谷滚动、拖拽摩擦和撞击的结果。不连续、不对称分布于兰溪下游凹岸的拦马墙巨砾堆积堤,沿流向延伸或呈流线构造,具有平行主流的平顶、陡坡砾石堆和立石等景观,砾石的圆度、分选和砾组构造均指向泥石流堆积堤或特大洪水巨石边滩。它可能是1668年7月25日郯城大地震保存下来的群发性灾害遗迹。

Issues on criteria and methods for discriminating Quaternary glacial relics:also on the origin of the boulder-piled levees in Mount Mengshan

The authenticity of glacial relics in the middle-low mountainous areas, eastern China, could only be discriminated through scientific practice and academic contention. Field measured data proves no Quaternary gla-cial relic exists in Mount Mengshan. Furthermore, the middle-low mountainous areas in Shandong Province where Mount Mengshan locates has found no last glacial geomorphic assemblage so far, which should contain three elements of glacial erosional landform, glacial depositional landform, and glaciofluvial depositional land-form. The form ratio of Lanxi Valley in Mount Mengshan, from 0. 07 to 0. 24, do not match the real U-shaped valleys'around the world. The scratches on the Lanxi Valley wall and the Lanmaqiang boulder-piled levee, which are considered as evidence of glacier presence, are not of uniqueness and exclusiveness. They are the result of gravel rolling, dragging, rubbing and striking along the valley. The Lanmaqiang boulder-piled levee, distributed intermittently and asymmetrically in the downstream concave bank extending downflow or linearly arranged, has landscapes of flattops paralleled to the mainstream as well as steep gravel piles and standing stones. The roundness, sorting, and fabric of gravels in the levee all point to its origin that is the boulder levee of debris-flow or the boulder-strewn bed of catastrophic flooding. The boulder-piled levee probably is the relic of group disaster caused by the Tancheng Great Earthquake on July 25 , 1668 .