Petrographical, petrochemical characteristics of granitoids in hon thung and Chau Vien mountains, Long Hải area, Bà Rịa-Vũng Tàu province

Abstract

The study area is located at Long Hai, Ba Ria-Vung Tau province. The petrographical components consist of medium to small - grained biotite granite. The vein rocks are inclusive of aplite, aplitic granite and pegmatoid. The main mineral components are plagioclase, potassium feldspar, quartz, biotite and little hornblende. The common accessory minerals are sphene, zircon, apatite, orthite and magnetite. Most of the rocks are subjected to intensive post-magmatic alteration, mainly albitization and microlinization proccesses. In the rocks there is SiO₂ = 72.68 - 76.06%, Al₂O₃  = 12.06 - 13.70%, Na₂O = 3.24 - 4.06%, K₂O = 4.18 - 5.12%. The common trace elements are Sn, W, Mo, Cu, Pb, Zr, Hf, Y, Yb.