Chemical characteristics of fluorine-bearing biotite of early Paleozoic plutonic rocks from the Sor Rondane Mountains, East Antarctica

• Main Authors: Zilong Li, Yoshiaki Tainosho, Kazuyuki Shiraishi, Masaaki Owada
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: East Antarctica; Mefjell; Sor Rondane Mountains; Sor-Rondane; Sør Rondane Mountains; Sør-Rondane; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.511.7041; http://www.terrapub.co.jp/journals/GJ/pdf/3702/37020145.pdf

The chemical compositions of biotite grains have been determined for early Paleozoic plutonic rocks from the Sør Rondane Mountains, East Antarctica. The plutonic rocks are divided into three groups of the type-I granitoids, type-II granitoids and the Mefjell Plutonic Complex. Two types of biotite are found in the groups: pale yellow to dark green biotite in the type-I granitoids and brown to dark brown biotite in the type-II granitoids and the Mefjell Plutonic Complex. Mineral chemically, biotites from the type-I granitoids have higher SiO2 contents, F contents, and XMg values with lower TiO2 and Cl contents relative to biotites from the type-II granitoids. In the type-II granitoids and the Mefjell Plutonic Complex, biotite strongly enriched in FeO has lower F contents. Biotites in the type-II granitoids and the Mefjell Plutonic Complex have much higher log ( fH O2)/ ( fHF) than those from the type-I granitoids. The fluorine content in biotite from the type-I granitoids is similar to that from partial melting A-type granites in Lachlan Fold Belt of eastern Australia; and those from the type-II granitoids and the Mefjell Plutonic Complex are comparable to fractionated aluminous A-type granites from the Lachlan Fold Belt, and the Ambalavayal aluminous A-type granites of South India. Lower fluorine contents in biotite from the type-II granitoids and the Mefjell Plutonic Complex may be mainly controlled by late-magmatic fluid-rock interaction processes associated with melt and may not be indicative of original magma contents. Higher fluorine contents in biotite and