摘要
菲尔德斯半岛新生代火山岩岩石组合为高铝玄武岩-玄武安山岩-安山岩-英安岩,是一套低钾高铝的钙碱性岩系。以岩石中Sr/Ca,Ba/Ca比值作为讨论岩浆演化的一个指标,确认高铝玄武岩为本区岩浆作用的初始岩浆,经过岩浆房中斜长石和单斜辉石为主的分离结晶作用,依次演化出玄武安山岩、安山岩和英安岩岩浆。
The 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 characterized and high Al concentrations, This has been confirmed with the major element composition, the trace element and the rare earth element concentrations of studied rocks. The volcanism in this area can be divided into two stages. Stratigraphically the Great Wall Formation was formed in the Paleocene and the Fossil Formation occurred on the boundary between Eocene and Oligocene.
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 analysed with NAA, the authors find that the Cenozoic volcanic rocks, high -Al basaltic volcanic rocks, whether from volcanic strata or from subvolcanic intrusions formed in different stages, could be considered as a primary member, and the fractional crystallization of clinopyroxene and plagioclase controlled the evolution of the primary magma and resulted in formation of the basaltic-andesitic, andesitic and dacitic magmas. This result strongly supports the petro-genesis model proposed from petrographical, mineralogical and petrochemical evidences. The evolution of the volcanic rocks on the Filldes Peninsula is estimated to be compatible with that in the southern Chile.
出处
《南极研究》
CSCD
1990年第1期27-34,共8页
关键词
火山岩
新生代
SR
BA
Ca
岩浆
演化
Fildes Peninsula, Genozoic volcanic rocks, Sr/Ca-Ba/Ca systc matics.
