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

Abstract

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.

Keywords

• the transantarctic mountains
• petrogenesis
• pluton
• i-type granite