在西澳大利亚,太古宙这个名词一般应用在早于2400Ma的岩层,这与最近由前寒武地层分会提出的2500Ma界线是有一定偏差的(James,《前寒武纪研究》,7,193—204页:1978)。无论应用那个标准,西澳大利亚地盾的二个最老部分—皮尔巴拉(Pilbara)和伊尔冈地块—在太古宙期间就已清楚确立。上述两个地块均以典型的绿岩—花岗岩类为主所组成,其中许多花岗岩类深成岩由含高比例火山岩同时形成的绿岩带所包 In Western Australia, the term Archean is generally applied to formations that are earlier than 2400 Ma, a departure from the 2500 Ma line recently proposed by the Precambrian strata (James, Precambrian Research, 7, pp. 193-204 : 1978). Whatever that criterion, the two oldest parts of the Western Australian shield, Pilbara and Ilgan, were clearly established during the Archean era. The above two blocks are dominated by the typical greenstone-granitoids. Many of these granitoids are composed of greenstone belts formed simultaneously with high volcanic rocks