南极横贯南极山脉休斯陡崖花岗质岩体的成因

为了探讨横贯南极山脉休斯陡崖花岗质岩体的岩石成因，对其开展了岩相学和岩石化学分析。结果表明，休斯陡崖岩体主体岩石为二长花岗岩，后期被细粒二长花岗岩岩脉侵入。二者都具有高硅、富碱和高钾特征，里特曼指数小于3，岩石铝饱和指数(A/CNK)值小于1；微量元素原始地幔标准化分布型式具有Rb、Th、U和K元素富集，Nb、Ta、Nd和Ti等元素亏损特征；稀土元素总量偏低，轻稀土富集。主期二长花岗岩的稀土元素球粒陨石标准化分布型式具有轻微的负Eu异常，而岩脉具有正的Eu异常。休斯陡崖岩体的岩石类型为钙碱性准铝质I型花岗岩，源区为下陆壳，并伴有幔源物质的混入。在源区，岩浆发生了不同程度的斜长石、钛铁矿、金红石和磷灰石的分离结晶作用，其形成的构造环境为与俯冲作用有关的火山岛弧环境。 

Petrogenesis of the Hughes Bluff granitic pluton in the Transantarctic Mountains, Antarctica

In order to elucidate the petrogenesis of the Hughes Bluff granitic pluton, the petrological and geochemical studies were conducted, and the results show that the Hughes Bluff granitic pluton is composed of monzogranite, intruded by fine-grained monzogranite dikes in the later period. They both are characterized by high abundance of silicon, alkali and potassium, enriched in Rb, Th, U and K and depleted in Nb, Ta, Nd and Ti relative to those of the primitive mantle, with the Rittmann Indexes less than 3 and the A/CNK values less than 1. They both also have a low total amount of rare earth elements and an abundance of light rare earth, showing weakly negative Eu anomaly and slightly positive Eu anomaly in the chondrite-normalized REE pattern for the monzogranite and granitic monzogranite dike respectively. All the data show that the rocks from the Hughes Bluff granitic pluton belong to the I-type granites, and the source region is probably the lower continental crust, but the contribution of mantle material cannot be ruled out. The magma in the source region underwent varying degrees of fractional crystallization of plagioclase, ilmenite, rutile and apatite, and was derived from a volcanic island arc environment related to subduction.