论文部分内容阅读
在研究金溪—南城变质混合岩带中混合岩、花岗岩的矿物岩石学基础上 ,详细研究了它们的Nd、Sr、Pb、O同位素组成。混合岩、花岗岩初始钕同位素组成 (14 3Nd/14 4 Nd) i=0 .5116 89～0 .511853,在εNd -T图中位于该地区结晶基底变粒岩、片岩Nd同位素演化域上方 ,褶皱基底绢云千枚岩Nd同位素演化线下方 ;初始锶同位素组成 (87Sr/86 Sr) i=0 .74 86 4～ 0 .752 57;氧同位素组成δ18O为 10 .2 3‰～ 14.89‰ ,相当于高氧花岗岩的氧同位素变化范围 (>10‰ ) ;放射性成因铅较低 ,μ =10 .0 7～ 10 .4 ,变化范围小 ,铅同位素组成位于上部地壳演化线上方。这表明混合岩、花岗岩是由成熟度高、富氧的变粒岩及片岩等变质沉积岩经部分重熔形成的。
Based on the study of the mineralogy and petrology of the mixed rocks and granites in the Jinxi-Nancheng metamorphic mixed belt, their Nd, Sr, Pb and O isotopic compositions were studied in detail. The initial neodymium isotope composition of mixed rocks and granites (14 3 Nd / 14 4 Nd) i = 0.5116 89 ~ 0.511853 lies in the εNd -T diagram above the crystalline basement granulites and schist above the Nd isotopic evolution of the schist, Under the Nd isotopic dating of phyllite phyllite, the initial strontium isotope composition (87Sr / 86 Sr) i = 0.74 86 4 ~ 0 .752 57 and the oxygen isotopic composition δ18O is 10.23 ‰ ~ 14.89 ‰ The range of oxygen isotope variation (> 10 ‰) in high-oxygen granite is lower; the radiogenic lead is lower, with a range of variation ranging from 10.07 to 10.4, and the Pb isotopic composition is above the upper crustal evolution line. This shows that the mixed rocks and granites are formed by partial remelting of metamorphic sedimentary rocks with high maturity, oxygen-rich granulites and schists.