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

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 Greatwall station belongs to the calic-alkalic series and the trachyandensite from the Deceive island Belongs to the enrich-K trachyandensite. The REE distritution pattern of basalt from the Greatwall station is gentle with no Eu abnormality, the trace elements content is in accord with taht of calic-alkalic basalt from volcano arc, the distribution pattern of standard MORB 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 struture.