年龄在25亿年以上的太古界岩石在各个大陆上出露的范围都很小。这些地区从平面上看,面积大体相近,约10至260万平方公里,大部分介于25至50平方公里之间。每个区是地壳的一个片断,是一个特定时期的记录。各个带通常表现出相似的构造形式。太古界地区的岩石年龄为25至38亿年。在这些地区出现有三种岩石组合。按相对数量排列为:花岗岩—绿岩组合、高级变质组合和克拉通盆地组合。花岗岩—绿岩组合的特征 Archaeozoic rocks older than 2.5 billion years of age are exposed on all continents to a very small extent. In terms of area, these areas are roughly the same in size, ranging from 10 to 2.6 million square kilometers, most of them between 25 and 50 square kilometers. Each area is a fragment of the crust, is a record of a particular period. Each band usually shows a similar form of construction. The Archean area has a rock age of 25 to 3.8 billion years. There are three rock combinations in these areas. The relative quantities are arranged as follows: granite-greenstone assemblage, high-grade metamorphic assemblage and cratonic basin. Characteristics of granite - greenstone assemblage