一、加拿大地盾地质北美大陆,以哈得逊湾为中心,广泛分布前寒武岩石,这个地区称为加拿大地盾(图1)。这个地区的沉积岩、喷出岩及以花岗岩为主的侵入岩类,一般都普遍受了变质(造山)作用;沉积作用和火山喷发,究竟哪个更老一点,尚未查明。近年来用 K-Ar 法测定年代结果表明,加拿大地盾至少有三个主要的造山运动时 First, the Canadian Geological Shield The North American continent, Hudson Bay as the center, widespread Precambrian rocks, this area known as the Canadian Shield (Figure 1). The sedimentary rocks, eruptive rocks and intrusive rocks dominated by granites in this area are generally subject to metamorphism (orogeny); sedimentation and volcanic eruptions, which are older, have not yet been identified. The K-Ar dating of recent years shows that the Canadian Shield has at least three major orogeny