一、引言 在加拿大的不列颠哥伦比亚、澳大利亚和新西兰的几个斑岩型矿床的薄片鉴定中,越来越感到“次生钾长石”这个术语过于简单化。事实上,原生侵入体中的斜长石显示出若干进化蚀变阶段。首先是出现钠长石的一些结构变种,然后是钠长石-正长石系列的碱性长石,最后是正长石本身。在所研究的斑岩体系中,以钠长石和碱性长石形式出现的蚀变广泛分布,而真正的次生正长石则不大常见。在中长石-奥长石斑晶中,比较普遍地发育有典型的钠长石交代长石。这种 I. INTRODUCTION In the identification of thin sections of several porphyry deposits in Canada, British Columbia, Australia and New Zealand, the term “secondary potash feldspar” is increasingly perceived as too simplistic. In fact, plagioclase in primary intrusions shows several evolutionary alteration stages. The first is the emergence of some structural variants of albite, followed by the alkaline feldspar of the albite-orthoclase series, followed by the orthoclase itself. In the porphyry system under study, the alteration occurs in the form of albite and alkaline feldspar. However, the genuine secondary feldspar is less common. In the mid-feldspar-arborescent porphyrite, the more widespread development of a typical albite feldspar. This