南极乔治岛某些火山岩的岩石学和地球化学特征

PETROLOGY AND GEOCHEMISTRY OF BASALT FROM THE GREAT-WALL STATION AND TRACHYANDENSITE FROM THE DECEIVE ISLAND, ANTACTIC

本文报道了南极乔治岛中国长城站玄武岩和欺骗岛粗安岩的岩石学和地球化学特征。利用中子活化分析测定了岩石中的稀土元素、微量元素和过渡族金属含量;利用电子探针、扫描电镜等手段观测了它们的造岩矿物特征和物质组成,最后推测南极乔治岛具有大陆地壳结构向大洋地壳结构过渡的特征。

Both the basalt from the Greatwall station and the trachyandensite from the Deceive Island are oval with porphyrite texture, their basemass is of the microcrystal plagiclase and glassmass; only the porphyrite crystal of the basic plagiclase, that of the latter is medium plagiclase and dispside.They are rich in Ti, V and others, but deficient in Cr, Co and Ni. The basalt from the Greatwaall station belongs to the calic-alkalic series and the trachyandensite from the Deceive island Belongs to the enrich-K trachyandensite.The REE distribution pattern of basalt from the Greatwall station is gentle with no Eu abnormality, the trace elements content is in accord with that of calic-alkalic basalt from volcano arc, the distribution pattern of standard MORE belongs to transition type of continental basalt and oceanic basalt. The REE pattern of trachyandensite from the Deceive island is rich in light REE, and Eu nagative. It can be inferred that the George island is an island arc with the transition properties of oceanic lithosphere structure to continental lithosphere structure.