绪言澳大利亚东南部元古代拉克伦(Lachlan)褶皱带中硅铝质火山岩比镁铁质型更为发育。古生代侵入岩也以硅质花岗岩类为主,根据其源岩是沉积的还是火成的,已将它们划分为S-型和Ⅰ-型(Chappell和White,1974)。 Owen和Wyborn(1979)首先指出,象花岗岩类一样,拉克伦褶皱带的一些火山岩也可以细分为S-型和Ⅰ-型。Johnston(1979)发现了堪培拉(Canberra)北部S-型单元之间 INTRODUCTION The Mesozoic Lachlan fold belt in southeastern Australia is more developed than mafic-type silicic-aluminum volcanic rocks. Paleozoic intrusives are also dominated by siliceous granites, which have been classified as S- and I-type (Chappell and White, 1974), depending on whether their source rocks were sedimentary or pyrophoric. Owen and Wyborn (1979) first pointed out that, like granitoids, some of the volcanic rocks in the Lakaran fold belt can also be subdivided into S-type and I-type. Johnston (1979) discovered the S-type units in northern Canberra