【摘要】 安徽铜陵地区中生代的岩浆岩岩体中产有多种矿物巨晶和岩石包体。笔者对产于曹山辉石闪长玢岩和鸡冠石花岗闪长岩中的辉石和角闪石巨晶及其堆积岩或堆积晶进行了详细的岩相学和矿物化学研究 ,并在此基础上估算了矿物平衡结晶的温压条件 ,讨论了安徽铜陵地区中生代幔源岩浆底侵作用问题。研究表明 ,铜陵地区大约在14 0Ma以前发生了碱性橄榄玄武质岩浆的底侵作用 ,辉石巨晶和角闪石巨晶及其堆积晶是由底侵的碱性橄榄玄武质岩浆在 2 8～ 33km深处的深位岩浆房中与下地壳发生同化混染作用形成的中基性岩浆经结晶分异作用形成的 ,而辉石堆积岩是由中基性岩浆在 19～ 2 1km深处的浅位岩浆房中与中地壳的浅变质岩系发生同化混染作用形成的中性岩浆经结晶分异作用形成的。更多还原

【Abstract】 The Caoshan and Jiguanshi intrusions composed of pyroxene dioritic porphyrite and granodiorite are exposed in the Shizishan orefield, Tongling, Anhui Province, eastern China. Based on new petrographic observations and microprobe analyses of pyroxene and hornblende megacrysts and cumulates from the intrusions, in combination with mineral crystallization temperature and pressure calculations, the authors found some evidence for the Mesozoic mantle-derived magma underplating in this area. The petrographic and mineralogical data presented in this paper suggest the existence of alkali-olivine basalt magma underplating before 140 Ma± in this area. The formation of the pyroxene megacrysts and the hornblende megacrysts as well as cumulates resulted from crystallization differentiation of intermediate-basic magma in the deep magma chamber at the depths of 28 km to 33 km through the assimilation of the underplated alkaline basaltic magma with the lower sima crust. The formationofthepyroxenecumulatesresultedfromthecrystallizationdifferentiationofintermediatemagma in the shallow magma chamber at the depths of 19 km to 21 km, through the assimilation of the intermediate-basic magma with the epimetamorphic rocks.更多还原