堆积岩与岩浆岩成分趋势线的相互预测原理及方法

The Principle and Method for Mutual Prediction of Compositional Trend Lines of Cumulates and Magmatic Rocks

本文在讨论了同源岩浆分离结晶过程中堆积相与残余岩浆相元素丰度关系公式的基础上，提出了堆积岩与相对应的（同源同结晶阶段）岩浆岩（狭义）成分趋势线的相互预测法则，并以冰岛玄武岩－流纹岩系和攀西地区峨眉山玄武岩系及相对应的层状堆积岩为例，厘定了多期岩浆分离结晶成因堆积岩系与岩浆岩系成分趋势相互预测的作图方法。

Based on the equation of element abundance relationship between cumulate and residual magma during fractional crystallization of magma, this paper prososes the principle and method for the mutual prediction of compositional trend lines of consanguineous cumulate rocks and magmatic rocks formed at the same crystallization stage. If the abundance constant R (the slope of the compositional trend line of magmatic rock) and the bulk partition coefficient D are known, the compositional trend line of the relevant cumulates could be predicted and vice versa.1. When R> 1, the compositional trend line of cumulates lies to the lower right side of the trend line of relevant magmatic rocks.2. When R<0, the compositional trend line of cumulates lies to the lower left side of the trend line of relevant magmatic rocks.3. When 0<R<1, the compositional trend line of cumulates lies to the upper left side of the trend line of relevant magmatic rocks.4. When R=1 or R=0, the compositional trend line of cumulates lies to the lower left side or left prolongation of the trend line of relevant magmatic rocks.The above rules could also be used to distinguish whether the genetically closely related cumulate rock and magmatic rock in the same area are consanguineous or not.