一、问题的提出 国际地质科学联合会火成岩分类学分会推荐了QAPF图解的分类方案(A.Streckeisen,1979)。这一方案的长处是:各类火山岩的平均成分投影点基本上落在相应的分区内;各区火山岩的名称可以同侵入岩相对 I. PROBLEM ISSUES The classification of QAPF diagrams is recommended by the International Union of Geological Magazines for Classification of igneous rocks (A. Streckeisen, 1979). The advantage of this scheme is that the projection of the average composition of various volcanic rocks basically falls within the corresponding subareas; the volcanic rocks in each area may have the same name as the intrusive rocks