AFC混合与铜陵地区侵入岩的成因  

AFC Mixing Model and Origin of Intrusive Rocks from Tongling Area

作　　者：邢凤鸣 徐祥[1] 

机构地区：[1]安徽省地质科学研究所

出　　处：《岩石矿物学杂志》1996年第1期10-20,共11页Acta Petrologica et Mineralogica

基　　金：国家八五科技攻关课题

摘　　要：岩浆的混合有多种方式。国内使用较多的是简单二元混合模式，但更为普遍的应该是ＡＦＣ混合，即在岩浆同化围岩的同时有矿物结晶伴随。根据热平衡原理，岩浆同化围岩所需要的热由结晶潜热提供，否则同化作用将很快中止。Ｎｄ、Ｓｒ同位素在反映ＡＦＣ混合时最为有效．根据Ｎｄ、Ｓｒ同位素数据，结合岩石学资料，应用ＤｅＰａｌｏ提出的公式所做的成因模拟表明，铜陵地区岩浆岩可能是幔源碱性玄武岩浆同化古老麻粒岩相下地壳的产物，幔源组份约占７０％。Mesozoic intrusions in Tongling area consist of gabbro, quartz diorite and granodiorite with an age of 137 Ma±. These intrusions are characterized by relatively high K2O,whole alkali and Sr contents but comparatively low Cr and Ni contents, belonging to K-high calc- alkaline series. They contain homoeogene enclaves such as pyroxenolite, hornblendite and hornblende - pyroxenolite, which are cumulates. The basic member of the intrusive rocks is silica- undersaturated . which formed silica - oversaturated rocks by assimilation. Petrological and isotopic data show that the intrusive rocks from Tongling area might have been formed by AFC mixing process, with the basic end -member being alkali basaltic magma and the acidic end - member being old granulite facies rocks in lower crust.AFC modeling calculation shows that AFC mixing curve with r = 0. 75, DNd= 0. 5 and DSr= 0. 5 can well fit the modal data of the intrusive rocks from Tongling area.

关 键 词：侵入岩 成因 AFC混合 岩浆 

分 类 号：P588.12[天文地球—岩石学]