Formation of the Archaean greenstone belt

1.热变质岩石造岩矿物的电子探针分析对变质火山岩和变质沉积物中的矿物进行了电子探针分析。即使在单一的变玄武岩中，角闪石的化学成分也有很大的差异。这表明在该区发生的热变质作用中没有达到平衡。X射线荧光分析主要用于花岗岩类和变质火山岩的分析。花岗岩类以岩基和岩株的形式出现。它们在岩相学上分为四种类型。不同类型的岩石之间的常量元素化学性质不同，属于同一岩石类型的岩体之间也不同。每一个花岗岩类岩体可能有不同的侵位历史。结论肯尼亚中生代绿岩带中的花岗岩类侵位于先存火山岩和沉积岩的浅部。接触晕的热结构取决于花岗岩体的岩石学特征和形状。花岗岩类-绿岩组合构成了晚白垩世古陆的上部，花岗岩类-高级岩组合构成了晚白垩世古陆的下部。

1. EPMA analyzes of rock-forming-minerals in the thermally metamorphosed rocksEPMA analyzes are made on minerals in metavolcanics and metasediments. Chemical composition of amphiboles varies considerably even in a single metabasalt. This suggests that the equilibrium is not attained during the thermal metamorphism that took place in this area.2. XRF bulk chemical analyzesXRF analyzes are made on granitoids and metavolcanics. Granitoids occur as batholiths and as stocks. They are petrographically classified into four types. Major element chemistry differs between rocks of different type and also differs between rock masses belonging to the same rock type. Each of the granitoid masses probably has a different history of its emplacement.3. ConclusionThe granitoids in the Archaean greenstone belt in Kenya emplaced in the shallow level of preexisting volcanic and sedimentary rocks. Thermal structures of the contact aureole depend on petrologic characteristics and shapes of the granitoid mass. The granitoid-greenstone association formed the upper part and the granitoid-high grade rock association formed the lower part in the Archaean Craton.