摘要
研究浙西北中生代火山岩的REE分布和锶同位素组成,得出如下结论:酸性和中酸性火山岩与侵入岩的REE分配型式相似,均为向右倾的、彼此近于平行的V型曲线,具有铕负异常;它们的REE参数〔δEu,Sm/Nb,∑LREE/∑HREE和(La/Yb)_N〕仅存在较小差异;^(??)Sr/^(86)Sr初始比值为0.7056-0.7139。表明火山岩及侵入岩的成岩物质都来源于大陆壳,它们是由同源的陆壳物质重熔所形成的岩浆,经分异、演化,先后侵入或喷出形成的。
Great similarity of REE distribution patterns has been established of both intrusive and vol-canic acidic and medium-acidic Mesozoic rocks, though their absolute REE contents are different.All. these rock types yield rightward declined V-shaped curves parallel to each other and withnegative Eu anomalies. The differences in REE parameters (δEu, Sm/Nd. ∑LREE/∑HREE and(La/Yb)_N) are in significant. The initial ^(87)Sr/^(56)Sr value for both intrusive and volcanic rocksranges from 0.7079 to 0.7139, showing their crustal origin. A comagmatic sialic crustal remeltingmechanism with subsequent differentiation, evolution, intrusion and volcanic extrusion is suggested.
关键词
中生代
火山岩
地球化学
成岩物质
rare earth
elements
strontium isotopes
geochemistry
source of rock-forming material
