RARE-EARTH.RICH EUDIALYTE AND DALYITE FROM A PERALKALINE GRANITE DYKE AT STRAUMSVOLA, DRONNING MAUD LAND, ANTARCTICA
RARE-EARTH.RICH EUDIALYTE AND DALYITE FROM A PERALKALINE GRANITE DYKE AT STRAUMSVOLA, DRONNING MAUD LAND, ANTARCTICA
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南极洲 DRONNING MAUD LAND STRAUMSVOLA 的近碱性花岗岩岩脉中富含稀土元素的二钠铁矿和铁钠铁矿
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
R. Rickard
中科院分区：
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作者：
C. Harris;R. Rickard
切割南极洲 Straumsvola 霞石正长岩杂岩的微花岗岩岩脉，含有富含 RE'E 的纯钠铁矿 (REE2O3 + Y2O3 ca, 8 wt,9o) 和稀有矿物钠铁矿。与最近发现的钠长岩的岩石（安普罗岩）相比，岩脉岩并不是特别钾质（wt.Yo K，zNa 0.83），但其成分与阿森松岛的花岗岩捕虏体相似，阿森松岛是首次发现钠长岩的地方。岩脉中的真二水岩比欠饱和过碱性岩石中的 R、EE 含量更高，但来自周围霞石正长岩中的 WGS 的真二水岩却并非如此。一般来说，过饱和过碱性岩浆中缺乏钙，使得真胞质物质能够在此类岩石中充当有效的EE汇。尽管罕见，但近碱性花岗岩中的 eudi alyte 应该总是富含 REE，而霞石正长岩中的 tlut 则不一定如此，因为这些岩石总是含有更多的钙。
A microgranite dyke that cuts the Straumsvola nepheline syenite complex, Antarctica, contains RE'E-rich eudialyte (REE2O3 + Y2O3 ca, 8 wt,9o) and the rare mineral dalyite. The dyke rock is not particularly potassic (wt.Yo K,zNa 0.83) compared to rocks in which dalyite has recently been discovered (amproites), but it is similar in composition to the granite xenoliths of Ascension Island, in which dalyite was firs[ recognized. Eudialyte in the dyke is richer in R,EE than that from undersaturated peralkaline rocks, but this is not true of rhe eudialyte from wgs in the surrounding nepheline syenite. The lack of Ca in oversaturated peralkaline magmas in general enables euclialyte to act as an effectivei?EE-sink in such rocks. Although rare, eudi alyte in peralkaline granites should always be REE-rich, whereas tlut in nepheline syenites need not be, as tlese rocks invariably are more calcic.