近年来,一种基岩表面石臼状微地貌(天然石臼)引起了学术界的关注,由此中国东部第四纪冰川问题再度掀起争论.关于天然石臼成因大体有:壶穴说、冰臼说、风蚀穴说、风化坑说,等等.显然,在不同情况下,其成因可能是不同的.笔者对青岛崂山考察发现,这里的晶洞花岗岩本来原生洞穴(晶洞或气泡洞)非常发育,它们对天然石臼的形成存在重要影响.不但几厘米的晶洞可以经过风化作用拓展成相当大的石臼,甚至一些较大的晶洞(气泡洞)与石臼在形态、尺度和分布上比较接近.因此推断,崂山的天然石臼是岩石原生洞穴沿节理和裂隙崩塌破坏后,暴露出来经风化作用改造而成,甚至有的石臼基本是晶洞破坏后的直接产物,而非所谓的“冰臼”.%In recent years,a mortar micro-landform( natural-mortar) on the bedrock surface has been reported frequently in the eastern part of China as tourist geology is developing. However, the genesis of Quaternary glaciation in East China has been debated for years. Different researchers used different names to explain the genesis of natural-mortar,such as "pothole" ,"glacial pothole" ,"deflation pit" ."weathering pit" and so on. Actually,the genesis of natural-mortar in different locations, different landforms and different rocks are different. The authors have carried out detailed field investigations of the Mount Laoshan, Qingdao, which is composed of Late Mesozoic miarolitic granites with its prominent peak height 1133 meters above sea level and is located on the shore of the Yellow Sea, China. We found a large amount of primary caves( miarolitic cave or bubble-like cave) in miarolitic granites of the Mount Laoshan, which show a significant impact on the genesis of natural-mortar, and examined the features of the mortar pits and measured the morphological parameters as well. This paper discusses the relationship between the granitic miarolitic caves and the origin of natural-mortars in the Mount Laoshan. From the investigation of these data, we conclude that: ( 1 ) the development of miarolitic granites is bound to affect the micro-landforms particularly in the case of large miarolitic caves occurring, and it must be regarded as the first and non-ignorable factor for analyzing the genesis of natural-mortar in the Mount Laoshan; (2) the shape, size and distribution of several large miarolitic caves in the Mount Laoshan are similar to natural-mortar; ( 3 ) the formation of natural-mortar in the Mount Laoshan can be fully explained by erosion and destruction of miarolitic cave, which was reformed by weathering and other external geologic forces,but not by so-called glacial potholes;(4)"miarolitic granite" and "natural-mortar" in the Mount Laoshan exists some possible links,so that it deserves our further study.
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