再论A型花岗岩的实质——与张旗先生等商榷

The essence of A-type granitoids:A discussion on the opinions held by Prof.Zhang Qi and some other researchers

A型花岗岩最实质的特征是富铁贫镁,是形成于相对还原条件的一大类长英质火成岩的集合。"A型花岗岩"这一术语本身是描述性的,没有岩石成因含义。对于常见的准铝质、过铝质A型花岗岩而言,其形成需要高的地温梯度,低压不是形成这些A型花岗岩的必要条件。

The essence of A-type granitoids is the enrichment of iron and the depletion of magnesium, and the A- type granitoids mean the collage of the felsic igneous rocks formed under the reduced environment. The term ＂A-type granitoids＂ is purely descriptive, and has no petrogenetic implications. The origin of the common meta- luminous and peraluminous A-type granitoids needs high geothermal gradient, whereas the low pressure is not the essential condition for generating these melts.