SYSTEMATIC COVARIATION OF SR, BA, CA ELEMENTS IN CENOZOIC VOLCANIC ROCKS ON THE F1LDES PENINSULA, WEST ANTARCTICA, AND ITS RELATION TO PETROGENESIS

Cenozoic volcanic rocks in the Fildes Peninsula are composed of High-Al basalt, basaltic andesite, andesite, and dacite belonging to a calc-alkaline volcanic series with low-K and high-Al characteristics. Using a new indicator, the Sr / Ca-Ba / Ca, systematics proposed by Onuma (1980, 1981) and Sr, Ba, Ca concentrations in volcanic lavas and subvolcanic rocks, the authors find that the high-Al basaltic volcanic rocks either in volcanic strata or in subvolcanic intrusives were formed from a primary magma, in different stages through the fractional crystallization of clinopyro-xene(Cpx)and plagioclasc (Pl) in the process of magmatic evolution, resulting in the formation of basaltic-andesitic, andesitic and dacitic rocks.