关键词: 南极,火山岩,微量元素,地幔源区

Abstract:

This paper studies systematically trace elements,REE and Sr isotopes of rocks collected from 5 different regions of Ross Island and Taylor Valley, Antarctica . Ratios of 87 Sr/ 86 Sr in all samples range from 0.703000 to 0.704532.Ratios of Th/Ta and Hf/Sm in volcanic rocks of each region are essentially constant,they can be classified into two groups.One group includes the samples from Cape Bird, Crater and southern bank of Bonney Lake. Their average ratios of Th/Ta and Hf/Sm are about 1.0773 and 0.8144 respectively.The other group includes the samples from Cape Evens and Cape Royds.Their average ratios of Th/Ta and Hf/Sm are about 0.1460 and 1.6580. All the features indicate that magma in the study area are almost free from contamination with crustal substance and probably derived from the two different magma sources in the mantle.All the dots of samples on La/Sm La and Ce/Yb Ce evince two different trends of magma differentiation, one of which including tephrite,basarite is considered as a major result of partial melting of equilibrium in the mantle,and the other including trachyte,ventrllite as a result of magma fractional crystallization. The fusibility of magma in mantle is about 1.46-3.57%.Properties of the mantle in the regions are also discussed generally. A conclusion is drawn that the first group is probably derived from magma resources of enrichment in LREE,U,Ta and so on.