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众所周知,火山岩特别是陆相火山岩,岩性、岩相变化很大。一比五万地质填图中以大致能圈定火山机构并反映出火山活动的喷发韵律为宜,在物质成分发生变化的火山岩系中,还应反映出所谓××质这种规律变化。笔者通过近二十年来在火山岩地区野外工作的实践,提出正确划分填图单元是火山岩地区一比五万地质填图成败的关键的观点,并将填图单元晦划分原则归纳为一句话,即“岩性、岩相加爆发指数”。在岩石定名方面,笔者认为,对粗粒级火山碎屑岩,将某一粒级碎屑在岩石中所占百分比大于百分之五十的传统命名法,改为
As we all know, volcanic rocks, especially continental volcanic rocks, lithology, lithofacies vary greatly. In a geological map of one to 50,000, volcanic structures can be roughly delineated and reflect the eruptive rhythm of volcanic activity. In the volcanic series with changes in the composition of matter, the change in the law called XX quality should also be reflected. The author put forward that the correct division of mapping units is the key point of the success or failure of one to fifty thousand geological mapping in the volcanic area through the practice of field work in the volcanic area in the past two decades and summarized the principle of dividing the mapping units into one sentence “Lithology, rock outburst index ”. In terms of rock naming, in the opinion of the author, for the coarse-grained pyroclastics, the traditional nomenclature, which accounted for more than 50% of the total amount of one-grade clastic debris in the rock, was changed to