四海山地区二长—正长花岗岩基本特征及成因探讨

Basic Characteristics of Monzonitic-orthoclase Granites and Its Origin Study in Shandong Area

四海山地区的二长—正长花岗岩具有细粒→粗粒的结构演化和酸性→偏酸富碱性的成分演化特点，并含有 Ｓ 型花岗岩中的典型副矿物钛铁矿，岩石化学成分显示其富硅富铝，稀土配分模式为地壳重熔型，综合判别图解表明它们属造山后期侵入岩。其源岩为硅铝质地壳，属 Ｓ 型花岗岩。认为所有以硅铝质地壳（ 包括灰色片麻岩和变质沉积岩） 为源岩岩浆的花岗岩都应属于 Ｓ

Monzonitic-orthoclase granites in Sihaishan area have the structure evolution from fine grain to coarse grain, and component evolution from acid to meta-acid and rich-alkaline, as well as include typical accesory mineral ilmenite which specially occurred in S-type granites. As showed by the chemical components, the granites are rich in silicium and aluminium, and their rare earth pattern model belongs to crust-remelting type, while the compond diagnostic diagram shows them as intrusives formed in the late of mountain making stage. Their source rocks are salic crust and the granites belong to S-type granites. It is also recognized that all granites possess the source rocks of salic crust including gray gneiss and metamorphic sedimentary rocks should belong to S-type granites.