攀西地区花岗岩类的微量元素地球化学

攀枝花-西昌地区有大量的花岗岩类出露,依据同位素年龄,至少可以分为三个形成时期。它们的微量元素和主元素地球化学特征表明,晋宁-澄江期的磨盘山花岗岩岩浆可能来自于下部地壳基性火山岩的重熔;摩挲营、沪沽岩体花岗岩浆来自上部地壳的硅铝层。海西-印支期的红格-矮郎河岩体为地壳物质混染幔源物质的壳幔混合岩浆的产物,而太和、茨达岩体可能是来自深部幔源岩浆经过早期结晶分离后晚期残留岩浆形成的。燕山期冕西花岗岩可能是攀西古裂谷萎缩封闭时地壳局部重熔形成的。     

攀西裂谷火成岩组合的微量元素地球化学

本文依据攀枝花-西昌裂谷四十几个火成岩的主要元素、过渡金属元素、稀土元素和其他微量元素的分析结果,探讨了这些岩石的成因和岩浆过程。从主要元素成分来看,明显地显示出双众数岩套的特征。过渡金属元素显示了Cr和Ni的强烈亏损与Ti的明显富集,反映了复杂的结晶分离作用历史。所有岩石的稀土元素分配型式都是富集型的,暗示出原始岩浆可能来自原始地幔的低程度部分熔融,玄武岩的亲石岩浆元素丰度经原始地幔值标准化后的分配型式,显示出一种介于碱性玄武岩与大陆拉斑玄武岩之间的图形,这支持了它们的裂谷大地构造环境,也暗示了原始岩浆来自深处的原始地幔区,可能是石榴二辉橄榄岩部分熔融的产物。     

TRACE ELEMENTS GEOCHEMISTRY OF GRANITOID IN PANXI AREA

A lot of granitoid rocks occur in Panxi area, SW China, which were formed during Jinningnian-Chengjiangnian, Hercynian-Indosinian and Yenshanian. According to their trace elements geochemical and petrochemical characteristics, they can be divided into calc-alkaline and alkaline granites. The petrogenesis and magma sources of these granitoid rocks are different. The Jinningnian-Chengjiangnian granitoid rocks include Mopanshan granite body, Moshaying granite body and Lugu granite body. The Mopanshan body might be formed by partial melting of the lower crust and due to refusion of basic volcanic rocks. The magma source of the Moshaying and the Lugu bodies might be formed by partial melting of the upper crust. The Hongge-Ailanghe granites belonging to the Hercynian-Indosinian may be products of complex melting from the crust-mantle materials caused by the increase of temperature during rifting stage in the area. The Cida and Taihe alkaline granites belonging to the Hercynian-Indosinian might be derived from