高镁安山岩/闪长岩类(HMA)和镁安山岩/闪长岩类（MA）：与洋俯冲作用相关的两类典型的火成岩类

High magnesian andesitic/dioritic rocks (HMA) and magnesian andesitic/dioritic rocks (MA)： two igneous rock types related to oceanic subduction

摘要: 提要：本文主要基于对实验岩石学成果的简要评述，讨论与洋俯冲作用有关的两类典型的火成岩类：楔形地幔在含水条件下橄榄岩局部熔融产生的高镁安山岩/闪长岩类（HMA）和俯冲洋壳局部熔融岩浆与地幔楔相互作用产生的镁安山岩/闪长岩类（MA）。提出：（1）识别HMA和MA必须同时运用两套参数系统：SiO2-MgO系统和SiO2-FeO/ MgO系统；（2）区别HMA和MA是在它们均符合LF-CA（低Fe钙碱趋势）特征条件下，再用SiO2-MgO系统进一步加以鉴别；（3）识别HMA和MA的方法，或用在给定SiO2时，MgO和FeO/MgO的具体数值，或用图解法。

Abstract: Abstract：This paper discusses two igneous rock types (HMA and MA) related to oceanic subduction based on a brief review of the experimental petrological data. On such a basis, some suggestions are put forward as follows： (1) The utilization of both the MgO % and FeO/MgO (% ratio) at given SiO2 as the diagnostic parameters is emphasized in recognition of HMA and MAl. (2) On the basis of the LF-CA (Low-Fe calc-alkaline) characteristics, HMA and MA may be distinguished from each other by using the SiO2%-MgO % parameter system. (3) Either of the two methods, i.e., the diagram approach (Fig.2&3) or the numeric approach (Table 1,2&3), may be used for the nomenclature of HMA and MA.