摘要
作者通过对冀西北张家口—赤城地区广泛出露的所谓混合岩化黑云斜长片麻岩的地质、矿物、岩石和地球化学研究,确定了它们是太古代的英云闪长质、花岗闪长质片麻岩,并且认为它们不是变质的火山-沉积岩,而是地壳中先存的镁铁质角闪岩或麻粒岩的重熔岩浆在固结或半固结状态下被长英质麻粒岩部分熔融产生的熔浆混合、交代形成的产物。
Detailed geological, chronological, mineralgocal, petrological and geochemical studies have been conducted of the Chicheng gneissic complex in northwestern Hebei Province. The gne-issic complex is composed mainly of tonalitic-granodioritic rocks according to the O'Connor's classification. The U-Pb zircon age of the gneissic complex is 2468^(+33)_(27) Ma., consistent with that of the rocks in the North Tonaliticgrano dioritic Gneiss Belt in the North China Platform. The Archean Chicheng gneissic complex is part of the belt.No significant difference in composition between early anhedral metasomatic and late semi-euhedral plagioclases suggests that the gneissic complex is not composed merely of mafic rocks replaced by felsic fluids. The REE pattrns in the complex, in conjunction with major and trace elements data, show that the gneissic complex is the mixture of felsic magma produced by partial melting of FI dacitic granulite and crystallate derived from the magma prodlced by 50% ± partial melting of TH 2 tholeiitic granulite and 40%± fractional crystallization of hornblend.
出处
《地球化学》
CAS
1988年第4期377-384,共8页
Geochimica
