PETROGRAPHICAL, PETROCHEMICAL CHARACTERISTICS AND CONDITION OF FORMATION OF GRANITOIDS IN CHAU VIEN MOUNTAINS, LONG HAI AREA, BA RIA - VUNG TAU PROVINCE

Abstract

On the basic of the investigation into materials composition, formation conditions, shows that: 1- Petrographical components consist of: The first phase: biotite granite, hornblende bearing biotite granite, The second phase: small-crystalled granite, and The vein phase are inclusive of aplitic granite and pegmatoid. 2- Most of the rocks are subjected to intensive post-magmatic alteration, mainly albitization and microlinization proccesses. Main mineral components are plagioclase, potassium feldspar, quartz, biotite and little hornblende. 3- The granitoid of Chau Vien mountain belong to calc- alkalin granite, type of I granite or VAG. Magma were formed at 14,3km in depth at 962°C with pressure of Ps 4,48 kbar and crytallised at 10,5 km in depth at 660-667 °C with pressure of Ps 2,5-3 kbar.