Pearce图解及其在岩浆岩研究中的应用

PEARCE DIAGRAMS AND THEIR USAGE IN STUDYING IGNEOUS ROCKS

Pearce 图解是 Pearce,T.H.(1968)提出的用来模拟地球化学数据的图解。这些图解是 A/Z—B/Z 投影图,其中 A、B 代表成分丰度或其复杂的线性组合,甚至可以是 CIPW 标准矿物含量;Z 是绝对丰度恒定的某一成分的绝对丰度。Pearce 图解在研究岩浆岩同源性、岩浆岩的成因和演化等方面,尤其是在研究岩浆的分离结晶作用中有其独到之处。本文全面总结了 Pearce 图解在岩浆岩研究中的应用以及参数 A、B、Z 的选择等问题,并在前人研究的基础上,对 Pearce 图解中 A/Z 和 B/Z 投影点趋势解释等问题提出了新的解释方法,推广了这一图解的应用。

Pearce Diagrams,presented by Pearce,T.H.in 1968,can be used in modelling geological data.These diagrams are A/Z—B/Z plots,on which A and B are composi- tional abundances or complex linear combinations,even norm abundances;Z is absolute abundances of a composition with constant abundance.Pearce Diagrams can be per- fetcly used in studying cogenesis,origin and variation of igneous rocks etc.,especially in fractional crystallization of magma.The paper comprehensively summarized the usage of Pearce Diagrams in studying igneous rocks and the choice of parameters A, B and Z,and developed a new interpreting method of A/Z vs B/Z trends on Pearce Diagrams based on the studies of predecessors.