粤北贵东岩体内基性岩脉的成因研究

A GEOLOGICAL STUDY OF BASlC DIKES IN GUIDONG GRANITE OF NORTHERN GUANGDONG PROVINCE

对贵东花岗岩体内的基性岩脉研究结果表明,岩脉的锶、氧、硫同位素组成均一致显示幔源衍生物特征;岩脉常量元素、微量元素以及稀土元素分析表明、岩脉经历了较完全的结晶分异作用,并遭受到一定程度的陆壳混染作用。由此得出结论,认为形成岩脉的岩浆来自起源于地幔深处并侵位于地壳浅部(<15Km)的二次岩浆房,岩浆在这里发生结晶分异作用,在其随后的上升侵位过程中经受了陆壳的混染作用。

A study of basic dikes in Guidong granite shows that the isotopic composition of Sr, O and S all indicates that the dikes are products of mantle-derived magma, while the charactoristics of maior element, trace clemeent and rear earth elemennt indicate that the basic dikes have undergone bath considerable fractional crystallization and contamination by contrnental crust. Thus it is concluded that the magma forming the basic dikes is derived from a secondary magma chamber which originated in the upper mantle and was sittuated in the shallow part of the crust (less then 15 Km.), where it underwent fractional crystallization and was contaminated by continetal crust during its sits subsequent intrusion.